WO2015012566A1 - Brightness deviation compensation apparatus and compensation method of display device - Google Patents

Brightness deviation compensation apparatus and compensation method of display device Download PDF

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Publication number
WO2015012566A1
WO2015012566A1 PCT/KR2014/006648 KR2014006648W WO2015012566A1 WO 2015012566 A1 WO2015012566 A1 WO 2015012566A1 KR 2014006648 W KR2014006648 W KR 2014006648W WO 2015012566 A1 WO2015012566 A1 WO 2015012566A1
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Prior art keywords
voltage
light emitting
organic light
current
driving transistor
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PCT/KR2014/006648
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French (fr)
Korean (ko)
Inventor
이정철
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네오뷰코오롱 주식회사
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Priority claimed from KR1020130086744A external-priority patent/KR20150011595A/en
Priority claimed from KR1020130149266A external-priority patent/KR20150064481A/en
Application filed by 네오뷰코오롱 주식회사 filed Critical 네오뷰코오롱 주식회사
Priority to CN201480042124.4A priority Critical patent/CN105453164B/en
Publication of WO2015012566A1 publication Critical patent/WO2015012566A1/en

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3258—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the voltage across the light-emitting element
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G09G2300/0861—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G09G2300/0861—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
    • G09G2300/0866—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes by means of changes in the pixel supply voltage
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/029—Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
    • G09G2320/0295—Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel by monitoring each display pixel
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/043—Preventing or counteracting the effects of ageing
    • G09G2320/045—Compensation of drifts in the characteristics of light emitting or modulating elements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0693—Calibration of display systems

Definitions

  • the present invention relates to a luminance deviation compensation device and a compensation method of a display device, and more particularly, to a luminance deviation compensation device and a compensation method of an organic light emitting display device using an organic light emitting device as a pixel display device of a display device.
  • an organic light emitting display device (hereinafter sometimes referred to simply as an organic light emitting display device) using an organic light emitting device (hereinafter referred to as an organic EL device) as a pixel of a display device has been in the spotlight.
  • the organic light emitting display device using this organic EL element as a light emitting element is attracting attention as a next-generation flat panel display device because it is light and thin and has excellent luminance characteristics and viewing angle characteristics compared to other display devices.
  • the organic EL device has a structure in which an organic light emitting layer containing an organic compound is inserted between a pair of electrodes formed of a positive electrode and a negative electrode formed on a transparent substrate such as glass, and holes are formed in the organic light emitting layer from the pair of electrodes. It is a light emitting device that generates an exciton by injecting and recombining holes and electrons, and displays or the like by utilizing the emission of light when the activity of the excitons is lost.
  • the organic light emitting layer is a thin film layer made of an organic material, the conversion efficiency of converting the color and current of light emitted into light is determined by the composition of the organic material forming the organic light emitting layer, different organic materials are different colors Generates light.
  • the organic material deteriorates and the efficiency at the time of light emission is reduced, thereby shortening the lifetime of the display device.
  • different organic materials may deteriorate at different rates depending on the color of light emitted, and a difference also occurs in deterioration of color.
  • the plurality of pixels constituting the display device cannot be deteriorated at the same speed as the other pixels, and the difference in the speed of the deterioration leads to uneven display.
  • the causes of such deterioration include an increase in the resistance value of the device itself and a decrease in luminous efficiency due to prolonged use of the display device.
  • the organic EL element has a characteristic that the resistance value of the element gradually increases when it emits light for a long time, and since the organic EL elements constituting the display device have different light emission frequencies, the cumulative emission time is inevitably different. Therefore, when the display device is driven for a long time, a variation in resistance value occurs between the organic EL elements, and thus a variation in emission luminance occurs, resulting in a luminance mura or a ghost image of the entire screen. have.
  • Another cause of deterioration is a decrease in the intensity of the light emitted from the organic EL element due to an increase in the threshold voltage due to deterioration with the elapse of use time of the thin film transistor (TFT) constituting the pixel, especially the driving transistor, and the threshold of the transistor.
  • the increase in voltage also varies among the plurality of transistors in the display device.
  • FIG. 1 is a circuit diagram showing a configuration of a display device driving circuit of Patent Document 1.
  • the conventional display device driving circuit has a pixel circuit 60 composed of the selection transistor 90, the driving transistor 70, and the organic EL element 50, as shown in FIG. 1, and the first voltage source 14.
  • a first switch S1 for selectively connecting the first voltage source 14 to the first electrode of the driving transistor 70, and an organic EL element having an anode connected to the second electrode of the driving transistor 70. 50, a second voltage source 15, and a second switch S2 for selectively connecting the cathode of the organic EL element 50 to the second voltage source 15.
  • the first electrode is connected to the second electrode of the drive transistor 70, the readout transistor 80, the current source 16, and the current source 16 to the second electrode of the readout transistor 80.
  • a third switch S3 selectively connected, a current sink 17, a fourth switch S4 selectively connecting the current sink 17 to a second electrode of the readout transistor 80, and a driving transistor And a voltage measuring circuit 18 connected to the second electrode of the readout transistor 80 to measure the voltage when the test voltage is applied to the gate electrode of 70.
  • the voltage measuring circuit 18 includes an A / D converter 18a for converting the measured voltage value into a digital signal, a processor 18b, and a memory 18c for storing the measured voltage value. Through the second electrode of the plurality of read out transistors 80, the voltage Vout from the pixel circuit 60 is sequentially read.
  • the processor 18b is connected to a data line of the pixel circuit 60 through a D / A converter 18e that converts a digital signal into an analog signal and provides a predetermined data value to the data line.
  • the processor 18b receives the display data Data input from the input terminal and compensates for the change described later, thereby providing the compensation data to the data line.
  • the first signal V1 indicating the characteristics of the driving transistor 70 is obtained by measuring the voltage at the second electrode of the transistor ().
  • the first signal is measured for each pixel of the entire plurality of pixels of the display device.
  • the first signal V1 is measured once before using the pixel circuit 60 as a display device, that is, before the driving transistor deteriorates by use, for example, and stores it as a first target signal in the memory 195. After that, after deterioration using the display device for a previously transmitted time, the first signal is measured in the same manner as described above and stored in the memory 18c.
  • the first switch S1 and the fourth switch S4 are opened, the second switch S2 and the third switch S3 are closed, and the readout transistor (using the voltage measuring circuit 18) is used.
  • the readout transistor using the voltage measuring circuit 18.
  • the second signal V2 is measured for each pixel of all the pixels constituting the display device, and like the first signal, the organic EL element 50 is operated before or after the use of the display device. Before deterioration and after deterioration using the display device for a previously transmitted time, the respective measurements are stored in the memory 18c.
  • the change in the characteristics of the driving circuit is compensated for by using the change in the first signal and the change in the second signal.
  • Patent Literature 2 calculates a correction signal for each organic EL element and a voltage sensing circuit including a transistor for sensing a voltage on one surface of each organic EL element of the organic light emitting display and generating a feedback signal. DESCRIPTION OF RELATED ART The display apparatus which compensates the output change of each organic EL element by applying the correction signal to the data which drives each organic EL element is described.
  • Patent Literature 1 since the first signal V1 indicating the characteristic change due to the deterioration of the driving transistor of each pixel circuit and the second signal V2 indicating the characteristic change due to the deterioration of the organic EL element are measured separately, Steps for measuring the characteristic change according to the use of the display device are complicated and cumbersome, and it takes a long time for the measurement.
  • the measurement of the characteristic change requires a readout transistor for each pixel, and requires four switches of the first to fourth switches, a multiplexer 40, and a separate current source.
  • the circuit configuration for measuring the characteristic change is complicated, which leads to a decrease in the aperture ratio of the display device, resulting in a decrease in the brightness of the display device.
  • a transparent organic field emitting light in both directions of the display device. This problem is more prominent in light emitting displays.
  • Patent Document 2 does not consider the deterioration of the driving transistor which is one of the causes of the deterioration of characteristics caused by the use of the display device, and thus cannot completely solve the problem of deterioration of performance caused by the long use of the display device.
  • Patent Document 1 WO2009 / 002406 Publication Pamphlet
  • Patent Document 2 Japanese Patent Application Laid-Open No. 2007-514966
  • the present invention has been made in view of the above-described problems, and the characteristic change due to deterioration of the driving transistor and the characteristic change due to deterioration of the organic EL element can be simultaneously measured in one step with a simple configuration, but the characteristic change compared with the conventional art. It is an object of the present invention to provide a luminance deviation compensation device and a compensation method of a display device having a simple circuit configuration for measuring.
  • the luminance deviation compensation device of the display device of the present invention for solving the above problems is a luminance deviation compensation device of an organic light emitting display device, a driving transistor having a first electrode, a second electrode and a gate electrode, and the A second voltage source connected to a first electrode, an organic light emitting diode having an anode connected to the second electrode of the driving transistor, a second voltage source, and a cathode of the organic light emitting diode; And a selection switch for selectively connecting between a voltage source and a current sink, and a current measuring circuit for measuring a current flowing from the first voltage source to the current sink when a test voltage is applied to the gate electrode of the driving transistor.
  • a luminance deviation compensating device of an organic light emitting display device including a plurality of pixel circuits in n rows and m columns, and a first voltage source and a second voltage source.
  • Each of the pixel circuits includes a driving transistor, an organic light emitting element that receives a voltage from the first voltage source when the driving transistor is turned on, and is connected to the first voltage source once, and selectively when the driving transistor is turned off.
  • a read transistor configured to apply a voltage to the one end side of the organic light emitting element, wherein the luminance deviation compensator includes a current sink and a second end of the organic light emitting element between the second voltage source and the current sink.
  • the luminance deviation compensation method of the display device of the present invention for solving the problem, the luminance deviation compensation method by the luminance deviation compensation device, the step of switching the selection switch to the current sink side, and the current measuring circuit And measuring a current flowing from the first voltage source to the current sink, and compensating for the luminance deviation of the organic light emitting display device from the measured current.
  • the luminance deviation compensation method of the display device of another embodiment of the present invention is a luminance deviation compensation method using the brightness deviation compensation device of another embodiment, wherein the plurality of the plurality of the plurality of the plurality of the light emitting diodes before the characteristics of the organic light emitting display device deteriorate.
  • a fourth step of measuring the voltage between the gate sources and the driving voltage of the organic light emitting diode, and the voltage between the gate sources of the driving transistors of each of the plurality of pixel circuits measured in the third and fourth steps, and the organic light emitting diode Threshold Voltage Fluctuations of the Driving Transistors of Each of the Pixel Circuits from the Driving Voltages of the Pixel Circuits and the Driving of the OLEDs A fifth step for calculating the pressure fluctuation.
  • the steps for measuring the characteristic change according to the use of the display device are simple and simultaneously measured. The time required for this can also be shortened.
  • the present invention can be easily switched to the measurement mode by a selection switch that selectively connects the common cathode of each pixel circuit of the display device between the second voltage source or the current sink, so that the measurement of the characteristic change of the display device can be measured. Since the circuit configuration is simple, and therefore, a substantial additional configuration for measuring the characteristic change is unnecessary, it is possible to simply construct a configuration for measuring the characteristic change of the display device without substantially reducing the aperture ratio.
  • 1 is a circuit diagram showing a configuration of a conventional display device driving circuit
  • FIG. 2 is a circuit diagram schematically showing the configuration of a display device of preferred embodiment 1 of the present invention
  • FIG. 3 is a circuit diagram showing important configurations of a specific pixel circuit and a luminance deviation compensating device of preferred embodiment 1 of the present invention
  • FIG. 5 is a circuit diagram schematically showing the configuration of a display device according to a second preferred embodiment of the present invention.
  • FIG. 6 is a circuit diagram showing important configurations of a specific pixel circuit and a luminance deviation compensating device of preferred embodiment 2 of the present invention
  • FIG. 7 is a flowchart showing the flow of the luminance deviation compensation method of the second preferred embodiment of the present invention.
  • FIG. 8 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element before the display device deterioration of the preferred embodiment 2 of the present invention
  • Fig. 9 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element after the display device deterioration of the preferred embodiment 2 of the present invention.
  • FIG. 2 is a circuit diagram schematically showing the configuration of a display device of preferred embodiment 1 of the present invention.
  • the display device of the first embodiment includes the display unit 100, the controller 120, the gate driver 130, the data driver 150, the anode driver 170, the selection switch 115, and a current.
  • a sink 160, an A / D converter 142, and a D / A converter 145 are included.
  • the display unit 100 includes a plurality of gate lines Lg1 to Lgn (n is an integer of 2 or more), a plurality of data lines Ld1 to m (m is an integer of 2 or more), and a plurality of anode lines La1, which are respectively disposed in parallel. n, and the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n are arranged in parallel with each other.
  • the plurality of data lines Ld1 to m intersect with the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n.
  • each pixel circuit P (i, j) is mentioned later.
  • the plurality of pixel circuits P (i, j) of the display unit 100 are connected to the gate driver 130 through the gate lines Lg1 to n, respectively, and the data driver through the data lines Ld1 to m. It is connected to the 150, and is connected to the anode driver 170 via the anode line (La1 ⁇ n).
  • the controller 120 generates a gate signal and a data signal for driving the display unit 100 according to the input image signal Data, the gate signal is supplied to the gate driver 130, and the data signal is the data driver 150. Supplied to.
  • the gate driver 130 is connected to the gate lines Lg1 to n, and supplies gate pulses corresponding to the gate signals to the respective gate lines Lg1 to n in a predetermined order.
  • the data driver 150 is connected to the data lines Ld1 to m, and is located on the pixel circuits P (i, which are located on the gate lines Lg1 to n through which the gate signals are supplied through the data lines Ld1 to m. j)), a data signal is supplied to the pixel to drive light emission.
  • the anode driver 170 outputs a voltage signal having a voltage V High or V Low to the pixel circuit P (i, j) through the anode lines La1 to n.
  • the voltage V Low is a voltage for turning the organic EL element 114 of each pixel circuit P (i, j) into a non-light emitting state during the writing process
  • the voltage V High is the pixel circuit P (i, j) is a voltage for causing the organic EL element 114 to emit light.
  • a common anode for simultaneously applying anode voltages to the anode lines La1 to n of the plurality of pixel circuits P (i, j) without separately installing the anode driver 13 is provided. ) May be used.
  • the selection switch 115 selectively connects between the cathode side of the organic EL element 114 of the pixel circuit P (i, j), which will be described later, and the current sink 160 or the second voltage source Vss.
  • the cathode of each organic EL element 114 is connected to the current sink 160 side, and when operating as a normal display device, the cathode of each organic EL element 114 is connected to the second voltage. In connection with the circle Vss, this operation may be performed under the control of the controller 120.
  • One end of the current sink 160 is connected to the selection switch 115, and the other end thereof is connected to the controller 120 through the A / D converter 142 and the pixel circuit P (i, j) by the selection switch 115.
  • a current of a predetermined constant value flows.
  • the current measuring circuit 140 will be described later.
  • Fig. 3 is a circuit diagram showing the main configuration of the pixel circuit and the luminance deviation compensating device of preferred embodiment 1 of the present invention.
  • the pixel circuit P (i, j) of the first embodiment includes an organic EL element 114, a driving transistor 112, a switching transistor 111, and a capacitor 113 as shown in FIG.
  • Each transistor 111 and 112 has a first electrode, a second electrode and a gate electrode.
  • the first electrode of the driving transistor 112 of each pixel circuit P (i, j) is connected to the other end of the first voltage source VDD and the capacitor 113, where the first voltage source VDD is separately provided.
  • the display device having the anode driver 170 may be a voltage source supplied through the anode driver 170, and the anode voltage is simultaneously applied to the anode lines La1 to n of the plurality of pixel circuits P (i, j). In the case of a so-called common anode to which is applied, it may be a voltage source for a common anode.
  • the second electrode of the driving transistor 112 is connected to the anode of the organic EL element 114, and the cathode of the organic EL element 114 is connected to the second voltage source Vss or current sink through the selection switch 115. And selectively connected to 160.
  • the gate electrode of the driving transistor 112 is connected to the switching transistor 111, and selectively provides data supplied through the data line Ldj to the driving transistor 112.
  • the gate electrode of the switching transistor 111 is connected to the gate driver 130 through a gate line Lgi, and the first electrode is turned on by a scan signal (row selection signal) supplied from the gate driver 130.
  • the image signal Data input to the data line Ldj is output to the gate electrode of the driving transistor 112 and one end of the capacitor 113.
  • the selection switch 115 selectively connects the cathode of the organic EL element 114 between the second voltage source Vss and the current sink 160, and in the case of operating as a normal display element, the organic EL element 114
  • the cathode and the second voltage source Vss are connected to each other, and the cathode and the current sink 160 of the organic EL element 114 are connected to each other when measuring the luminance deviation of the present invention.
  • a cathode of a plurality of pixel circuits P (i, j) in n rows and m columns is connected to each other, and a common cathode is one common cathode. It is connected to one second voltage source Vss through the selection switch 115.
  • the current measuring circuit 140 includes an A / D converter 142, a controller 120, and a processor 141 for converting a current measurement value into a digital signal, and the digital signal from the A / D converter 142 is Transmitted to the processor 141.
  • the current measuring circuit 140 further includes a memory 144 for storing the current measured value, and a low pass filter 143 as necessary.
  • the current measuring circuit 140 is selectively connected to the common cathode of the plurality of pixel circuits P (i, j) of the display unit 100 through the current sink 160 and the selection switch 115, and the plurality of pixel circuits. The current flowing through each of (P (i, j)) is sequentially read.
  • the processor 141 is connected to the data line Ldj via the D / A converter 145, and supplies a predetermined data value through the data line Ldj at the time of measuring the luminance deviation of the present invention.
  • the processor 141 receives the image signal Data through the input terminal and compensates for the luminance described below. Thus, when operating as a normal display device, the compensation data is transmitted through the pixel circuit P (i) through the data line Ldj. , j)).
  • the controller 120 also functions as the processor 141 of the current measurement circuit 140.
  • the present invention is not limited thereto, and the display device may be configured separately from the controller 120.
  • the cause of the decrease in luminance due to the use of the organic light emitting display device is that the threshold voltage is increased due to the deterioration of the driving transistors constituting each pixel circuit and the voltage is changed due to the change in the internal resistance of the organic EL element. Can be mentioned.
  • the luminance of the organic light emitting diode display is related to the amount of current flowing through each pixel circuit of the organic light emitting diode display, and is compensated for by collectively compensating the voltage change due to the increase of the threshold voltage of the driving transistor and the change of the internal resistance of the organic EL element.
  • the basic idea of the present invention is to adjust the amount of current flowing through each pixel circuit of the light emitting display device to a value suitable for maintaining appropriate luminance, thereby compensating for a decrease in luminance due to prolonged use.
  • a difference occurs in the degree of deterioration of the luminance of each pixel circuit according to the emission frequency of each of the plurality of pixel circuits or the difference in the organic light emitting layer material of each pixel circuit. Compensation must be made separately for each of the plurality of pixel circuits.
  • the current value flowing through each pixel circuit is measured before deterioration due to the use of the display device, for example, before the organic light emitting display device is used as the display device.
  • This measured current value is referred to as the reference current value, and the current value flowing through each pixel circuit is measured after the display device deteriorates by use for a predetermined time, so as to compensate the measured value after degradation based on the reference current value.
  • FIG. 4 is a flowchart showing the flow of the luminance deviation correction method according to the first preferred embodiment of the present invention.
  • the selector switch 115 is switched to the current sink 160 side (step S11), and then a predetermined test voltage Vdata is applied to the data line Ldj (step S12), and the selected gate line Lgi is turned on. Activate (step S13).
  • steps S12 and S13 may be reversed. That is, after activating the selected gate line Lgi, the predetermined test voltage Vdata may be applied to the data line Ldj. In practice, these two steps are synchronized with each other.
  • the switching transistor 111 of the pixel circuit P (i, j) is turned on and the test voltage Vdata applied to the gate line Lgi is applied to one end of the gate electrode and the capacitor 113 of the driving transistor 112. Output to.
  • step S14 when an anode voltage is applied from the first voltage source VDD (step S14), current flows from the first voltage source VDD through the driving transistor 112 and the organic EL element 114 to the current sink 160.
  • the current measurement circuit 140 measures this current, that is, the current flowing through the pixel circuit P (i, j), and stores the measured current value in the memory 144 (step S15).
  • the measurement of the current flowing through the pixel circuits must be made for each of the plurality of pixel circuits, so that the pixel circuit to be measured is determined in step S16. Determine if it remains.
  • step S16 Yes
  • a method of measuring a current value flowing in each pixel circuit for each of the plurality of pixel circuits in the n-row m column there may be a method of sequentially measuring the rows of the plurality of pixel circuits in the n-row m column, or a method of sequentially measuring the columns. Can be.
  • the test voltage Vdata is sequentially applied to the data line Ldm to measure the current value flowing through each of the pixel circuits of the first row, and then the pixel circuits of the second row, the third row,.
  • the current value flowing through each pixel circuit can be measured in the same manner as described above.
  • the sequential pixel circuits P (1, 1) for example, in the state in which the test voltage Vdata is first applied to the data line Ld1, for example in FIG. 2.
  • Pixel circuits P (2, 1),... Gate lines Lg1, gate lines Lg2 of the pixel circuit P (n, 1),... It activates by applying a sequential gate signal to the gate line Lgn, and measures the electric current which flows in each pixel circuit of a 1st column, and then the 2nd, 3rd, ...
  • the current value flowing through each pixel circuit may be measured in the same manner as described above.
  • the pixel circuits P (1,1) in the first row and the first column start at the pixel circuits P (n, m) in the nth row m columns, but the present invention is not limited thereto. It is not necessary to start from any pixel circuit among the plurality of pixel circuits in n rows m columns. It is important to measure and store the current value flowing through each pixel circuit for all the plurality of pixel circuits in n rows m columns.
  • the measurement of the current value flowing in each pixel circuit for compensation of the luminance deviation according to the long time use of the organic light emitting display device is measured first before use, that is, before deterioration of the organic light emitting display device.
  • This primary measured value is stored as a target current value, and then it is necessary to measure and store it after the predetermined time of use, i.e., after deterioration, in the same manner as the measurement method before deterioration.
  • test voltage Vdata should naturally be the same value in the measurement before and after deterioration.
  • the change in the current value is calculated by comparing the two values from the measured value before deterioration, that is, the target current value and the measured value after deterioration, and comparing the change in the current value before and after deterioration (step S17).
  • This calculation may be by a known method, and the gate electrode of the driving transistor 112 required to maintain each of the plurality of pixel circuits of the display unit 100 at a desired luminance by the known method by using a known method.
  • the value may be converted into a value of an offset voltage at and stored in the memory 144 in the form of a lookup table, for example.
  • the present invention is not limited thereto, and the offset voltage calculation algorithm may be stored in the memory 144 instead of the lookup table, and the offset voltage may be calculated by this algorithm when necessary.
  • the calculated offset voltage collectively includes a luminance deviation due to a change in the threshold voltage of the driving transistor 112 of each pixel circuit P (i, j) and a change in the current value due to deterioration of the organic EL element 114. It is provided as a data to compensate at a time.
  • the offset voltage is provided to, for example, the controller 120, and the controller 120 corrects the image signal Data input through the input terminal by the offset voltages calculated for each of the plurality of pixel circuits.
  • the controller 120 corrects the image signal Data input through the input terminal by the offset voltages calculated for each of the plurality of pixel circuits.
  • FIG. 2 is a circuit diagram schematically showing the configuration of an organic light emitting display device according to a second preferred embodiment of the present invention.
  • the display unit 200 the selection switch 215, the current sink 260, the current measurement circuit 240, the variation value correction unit 220, and the data driver are shown.
  • a gate driver applying a selection signal to each gate line Lgi and a driving voltage applied to each anode line Lai from the first voltage source VDD are included. It also includes well-known configurations, such as an anode driver and the controller which controls each part of a display apparatus.
  • the display unit 200 includes a plurality of gate lines Lg1 to Lgn (n is an integer of 2 or more), a plurality of data lines Ld1 to m (m is an integer of 2 or more), and a plurality of anode lines La1, which are respectively disposed in parallel. n, and the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n are arranged in parallel with each other.
  • the plurality of data lines Ld1 to m intersect with the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n.
  • m and n are natural numbers, respectively, and the plurality of pixel circuits P (i, j) are arranged in a matrix form of n rows and m columns (m and n are natural numbers, respectively) to form the display unit 200.
  • Each of the plurality of pixel circuits P (i, j) has a read line Lri, and the detailed configuration of each pixel circuit P (i, j) including the read line Lri will be described later.
  • the plurality of pixel circuits P (i, j) of the display unit 200 are connected to the gate driver 230 through the gate lines Lg1 to n, respectively, and the data driver through the data lines Ld1 to m. It is connected to the 250 and is connected to the anode driver 270 through the anode lines La1 to n.
  • the data driver 250 is responsible for applying the image signal Data to each of the plurality of pixel circuits P (i, j) through the plurality of data lines Ldj.
  • the driving transistor 212 and the reading transistor 216 are respectively measured. It is also in charge of applying the test voltage (Vdata) to. Details will be described later.
  • the selection switch 215 selectively connects the cathode side of the organic EL element 214 of the pixel circuit P (i, j), which will be described later, between the current sink 260 and the second voltage source Vss.
  • the threshold voltage fluctuations of the driving transistors 212 for each pixel circuit P (i, j) are measured and the driving voltage fluctuations of the organic EL elements 214 are measured, the luminance of each organic EL element 214 is measured.
  • the cathode is connected to the current sink 260 side, and when operating as a normal display device, the cathode of each organic EL element 214 is connected to the second voltage source Vss, and this operation is controlled by a controller of an illustrated figure. Can be made under.
  • One end of the current sink 260 is connected to the selection switch 215, and the other end thereof is connected to the variation correction unit 220 through the current measurement circuit 240, and the pixel circuit P (i, j) a predetermined value of current is applied to each pixel circuit P (i, j) of the display unit 200 when a predetermined data value is applied to the data line Ldj when the cathode of the organic EL element 214 is connected. Shed.
  • the current measuring circuit 240 includes a current measuring unit 242, an A / D converter 243, a variation calculating unit 241, and a memory 244, which will be described later in detail.
  • Fig. 6 is a circuit diagram showing a main configuration of a pixel circuit and a luminance deviation compensating device of preferred embodiment 2 of the present invention.
  • Each of the pixel circuits P (i, j) of the second embodiment has an organic EL element 214, a driving transistor 212, a switching transistor 211, a read transistor 216 and a capacitor as shown in FIG. 213, each transistor 211, 212, 216 has a first electrode, a second electrode, and a gate electrode.
  • the gate electrode of the switching transistor 211 is connected to a gate driver (not shown) through the gate line Lgi, the first electrode is connected to the data line Ldj, and the second electrode is a gate of the driving transistor 212.
  • the driving transistor 212 Is output to one end of the gate electrode and the capacitor 213.
  • the first electrode of the driving transistor 212 of each pixel circuit P (i, j) is connected to the first voltage source VDD and the other end of the capacitor 213, where the first voltage source VDD is separately
  • the display device may be a voltage source supplied through the anode driver, and the anode voltage is simultaneously applied to the anode lines La1 to n of the plurality of pixel circuits P (i, j).
  • the voltage source may be a common anode.
  • the second electrode of the driving transistor 212 is connected to the anode of the organic EL element 214, and the cathode of the organic EL element 214 is connected to the second voltage source Vss or current sink through the selection switch 215. It is selectively connected to any one of 260.
  • the gate electrode of the driving transistor 212 is connected to the switching transistor 211, and selectively drives the image signal Data (or test voltage Vdata) supplied through the data line Ldj. To provide.
  • the gate electrode of the read transistor 216 is connected to a read driver (not shown) through the read line Lri, and the first electrode is connected to the first electrode of the data line Ldj and the switching transistor 211, and the second electrode.
  • the electrode is connected to the second electrode of the driving transistor 212 and the anode end of the organic EL element 214, and is turned on by a selection signal supplied from a read driver (not shown) to be input to the data line Ldj.
  • the voltage Vdata is supplied to the anode terminal of the organic EL element 214.
  • the read driver for selectively driving the read transistor 216 may have a function of a gate driver of a known organic light emitting display device, or may further include a read driver separately from the gate driver. If the gate driver also functions as a read driver, a switching function for selectively selecting either the switching transistor 211 or the read transistor 216 may be added to the known gate driver.
  • the cathodes of the plurality of pixel circuits P (i, j) in n rows and m columns are connected to each other, and the common cathode is one common cathode. It is connected to one second voltage source Vss through the selection switch 215.
  • the current measuring circuit 240 includes a current measuring unit 242 and a current measuring unit 242 for measuring a current flowing through each pixel circuit P (i, j) through the selection switch 215 and the current sink 260.
  • the A / D converter 243 converts the analog signal measured by the digital signal into a digital signal, and compares the characteristic values of each pixel circuit P (i, j) before and after deterioration of the display device to be described later.
  • a variation value calculating section 241 and a memory 244 storing these values.
  • the current measurement circuit 240 is selectively connected to the common cathode of the plurality of pixel circuits P (i, j) of the display unit 200 through the current sink 260 and the selection switch 215.
  • the current flowing through each of the plurality of pixel circuits P (i, j) is sequentially read, and the threshold voltage fluctuation value of the driving transistor 212 and the driving voltage fluctuation value of the organic EL element 214 which are described later are calculated therefrom.
  • the variation value correction unit 220 is an image signal inputted through an input terminal of the threshold voltage variation value of the driving transistor 212 and the driving voltage variation value of the organic EL element 214 calculated by the variation value calculation unit 241 by the method described below. Data is added to each pixel circuit P (i, j) of the display unit 200 through the D / A converter 245 and the data line Ldj.
  • the D / A converter 245 converts the digital data supplied from the variation correction unit 220 to the pixel circuits P (i, j) of the display unit 200 into analog data.
  • the variation correction unit 220 may have a controller that controls the operation of a known organic light emitting display device as a whole, and may have a function independent of the controller. good.
  • the cause of the decrease in luminance due to the use of the organic light emitting display device is the variation of the threshold voltage due to the deterioration of the driving transistors constituting each pixel circuit and the driving voltage due to the change in the internal resistance of the organic EL element. Fluctuations.
  • the luminance of the organic light emitting diode display is related to the amount of current flowing through each pixel circuit of the organic light emitting diode display and compensates for the change in the driving voltage due to the variation of the threshold voltage of the driving transistor and the internal resistance of the organic EL element.
  • the basic idea of the present invention is to adjust the amount of current flowing through each pixel circuit of the light emitting display device to a value suitable for maintaining an appropriate luminance, thereby compensating for a decrease in luminance due to prolonged use.
  • a deviation occurs in the degree of deterioration of the luminance of each of the plurality of pixel circuits according to various variables such as the emission frequency of each of the plurality of pixel circuits or the difference of the organic light emitting layer material of each pixel circuit. Compensation must be made separately for each of the plurality of pixel circuits.
  • a test voltage having a predetermined value is applied to each pixel circuit before deterioration due to the use of the display device, for example, before the organic light emitting display device is used as the display device.
  • the driving voltage of the organic EL element are respectively measured, and the threshold voltage variation of the driving transistor and the driving voltage variation of the organic EL element are compensated for from the measurement result.
  • Fig. 7 is a flowchart showing the flow of the luminance deviation compensation method of the second preferred embodiment of the present invention.
  • the gate-source voltage V GS21 and the organic EL element 214 of the driving transistor 212 of each of the plurality of pixel circuits of the display unit 200 before deterioration of the organic light emitting display device is measured and stored in the memory 244 in association with each of the plurality of pixel circuits (step S21).
  • the measurement before deterioration of the organic light emitting display device may be measured in an initial state before using the organic light emitting display device as a display device, or may be measured when the operation of the organic light emitting display device is stabilized by use of a predetermined time. You may measure at other times.
  • Fig. 8 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element before the display device deterioration of the preferred embodiment 2 of the present invention.
  • the select switch 215 is switched to the current sink 260 side (step S31), and then the switching transistor 211 and the driving transistor 212 of the selected pixel circuit P (i, j) to be measured are turned off. On and the read transistor 216 are turned off (step S32).
  • a test voltage Vdata having a predetermined value is applied to the selected pixel circuit P (i, j) (step S33).
  • a test voltage Vdata having a predetermined value is applied to the selected pixel circuit P (i, j) (step S33).
  • the switching transistor 211 is turned on by applying the row selection signal to the gate terminal of the pixel circuit P (i, j) where the gate driver is selected, and thus the driving transistor 212 is turned on as the switching transistor 211 is turned on. ) Is also turned on so that a test voltage Vdata (5V in the second embodiment) of a predetermined value is applied to one end of the gate electrode and the capacitor 213 of the driving transistor 212 through the data line Ldj.
  • Vdata 5V in the second embodiment
  • the current measuring unit 242 measures this current, that is, the current (I OLED1 ) flowing through the selected pixel circuit (P (i, j)) and The measured current value is converted into a digital value by the A / D converter 243 and stored in the memory 244 (step S34).
  • the pixel circuit P (i, j) It is assumed that the current I OLED1 flowing through the organic EL element 214, that is, the current I OLED1 measured by the current measuring unit 242 is 1 ⁇ A. Current ”.
  • the fact that the current I OLED1 flowing in the organic EL element 214 of the selected pixel circuit P (i, j) is 1 ⁇ A for the convenience of explanation, the plurality of pixel circuits in the n-row m-column of the display unit 200
  • the current value of one specific pixel circuit P (i, j) is described as an example, and is measured from pixel circuits other than the specific pixel circuit P (i, j) among a plurality of pixel circuits in n rows and m columns.
  • the current value may be the same as the current value of the specific pixel circuit P (i, j), or may be a different value, which is a gate voltage V G and a source voltage of the driving transistor 212 described below.
  • V S the gate-to-gate voltage V GS
  • the driving voltage V OLED of the organic EL element 214 is 1 ⁇ A for the convenience of explanation.
  • test voltage Vdata (V in the second embodiment) of the predetermined value applied to the gate electrode of the driving transistor 212 and one end of the capacitor 213 is the anode voltage applied from the first voltage source VDD. Is a different voltage than.
  • step S35 the switching transistor 211 and the driving transistor 212 are turned off and the read transistor 216 is turned on (step S35) to apply the test voltage Vdata to the organic EL element 214 (step S36).
  • the test voltage Vdata applied to the organic EL element 214 is equal to the current I OLED1 flowing in the selected pixel circuit P (i, j) measured in step S34 (in the second embodiment) 1 kV is a voltage for flowing into the pixel circuit P (i, j), and the voltage value is measured in step S36.
  • the voltage measured in step S36 is 2V.
  • step S37 in which the voltage V GS21 between the gate and source of the driving transistor 212 of the pixel circuit P (i, j) selected from the above result and the pixel circuit P (i, j) of the pixel circuit P (i, j) are selected.
  • the driving voltage V OLED1 of the organic EL element 214 is calculated.
  • the gate voltage V G of the driving transistor 212 when the operating current I OLED1 of the pixel circuit P (i, j) is 1 ⁇ A is 5V, and the source voltage V S is Since it is 2V, the gate-source voltage V GS21 becomes 3V, the drive voltage V OLED1 of the organic EL element 214 becomes 2V, and these values are stored in the memory 244 in correspondence with the pixel circuit.
  • the measurement of the current flowing through each pixel circuit should be made for each of the plurality of pixel circuits, and therefore, the pixel circuit to be measured in step S38. Determine whether is left.
  • step S38 Yes
  • the voltage between the gate sources V GS21 of the driving transistor 212 of each pixel circuit and the driving voltage V OLED1 of the organic EL element 214 are measured by n.
  • the present invention is not limited thereto. It is not necessary to start from any pixel circuit among the plurality of pixel circuits in n rows m columns.
  • the gate-to-gate voltage V GS21 of the driving transistor 212 of each pixel circuit and the driving voltage V OLED1 of the organic EL element 214 are measured for all of the plurality of pixel circuits in n rows m columns.
  • the pixel circuits may be stored in correspondence with each pixel circuit.
  • the voltage V GS22 between the gate sources of the driving transistors 212 of each of the plurality of pixel circuits of the display unit 200 after deterioration of the organic light emitting display device, and the driving voltage V of the organic EL element 214. OLED2 ) is measured and stored in the memory 244 in association with each of the plurality of pixel circuits (step S22).
  • the measurement after deterioration of the organic light emitting display device is performed after using the organic light emitting display device as a display device for a predetermined time. Can be determined accordingly.
  • the number of times of measurement may be one or two or more times during the lifetime of the organic light emitting display device. In other words, compensation for the luminance deviation due to deterioration of the organic light emitting display device may be performed only once in the life cycle of the organic light emitting display device or may be performed two or more times.
  • the timing and frequency of measurement after deterioration can be appropriately determined as necessary.
  • Fig. 9 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element after the display device deterioration of the preferred embodiment 2 of the present invention.
  • step S41 the selection switch 215 is switched to the current sink 260 side (step S41), and then the switching transistor 211 and the driving transistor 212 of the selected pixel circuit P (i, j) are turned on,
  • the read transistor 216 is turned off (step S42).
  • step S41 and step S42 may be performed by the same method as step S31 and step S32 in the measurement before deterioration.
  • test voltage Vdata is applied to the driving transistor 212, and the voltage is measured.
  • the test voltage Vdata of the selected specific pixel circuit P (i, j) is 5.2V.
  • step S45 the step before deterioration is performed.
  • the read transistor 216 reads the test voltage Vdata for flowing the current I OLED having the same value as the reference current measured in S34 (1 mA in the second embodiment) to the selected pixel circuit P (i, j). Is applied to and the value is measured. In the second embodiment, it is assumed that the measured test voltage Vdata is 2V.
  • step S46 in which the voltage V GS22 between the gate and source of the driving transistor 212 of the pixel circuit P (i, j) selected from the above result and the pixel circuit P (i, j) are changed .
  • the driving voltage V OLED2 of the organic EL element 214 is calculated.
  • the gate voltage V G of the driving transistor 212 when the operating current I OLED2 of the pixel circuit P (i, j) is 1 ⁇ A is 5.2V and the source voltage V S.
  • the measurement of the current flowing through the pixel circuits must be made for each of the plurality of pixel circuits, so that the pixel circuit to be measured is determined in step S47. Determine if it remains.
  • step S47 Yes
  • the voltage V GS21 between the gate sources of the driving transistors 212 of each of the plurality of pixel circuits measured in step S21 and the driving voltage V OLED1 of the organic EL element 214 are measured in step S22.
  • the difference between the voltage V GS22 between the gate sources of the driving transistors 212 and the driving voltage V OLED2 of the organic EL device 214 of each of the plurality of pixel circuits is calculated and then the respective pixel circuits P (i, j
  • the threshold voltage variation value ⁇ Vth and the driving voltage variation value ⁇ V OLED are calculated, and the calculated threshold voltage variation value ⁇ Vth and the driving voltage variation value ⁇ V OLED are added together ( ⁇ Vth + ⁇ V).
  • OLED is stored in the memory 244 as a compensation voltage (step S23).
  • the gate source-to-gate voltage V GS21 of the driving transistor 212 measured in step S21 for the specific pixel circuit P (i, j ) is 3V, and the driving voltage of the organic EL element 214. Since V OLED1 is 2V, the voltage V GS22 between the gate sources of the driving transistor 212 measured in step S22 is 3.2V, and the driving voltage V OLED2 of the organic EL element 214 is 2V, so that a specific pixel is obtained.
  • the compensation voltage of the pixel circuit P (i, j) obtained by adding the threshold voltage variation ⁇ Vth and the driving voltage variation ⁇ V OLED is + 2V.
  • the threshold voltage fluctuation value? Vth and the driving voltage fluctuation value? V OLED are calculated in the same manner, and the calculated thresholds of the pixel circuits are calculated.
  • the value ⁇ Vth + ⁇ V OLED which is the sum of the voltage fluctuation value ⁇ Vth and the driving voltage fluctuation value ⁇ V OLED, is used as the compensation voltage of the pixel circuit, respectively, and is stored in the memory 244.
  • step S24 the selection switch 215 is switched to the second voltage source Vss side in step S23, and the compensation voltage obtained in step S23 is supplied from the memory 244 to the variation correction unit 220, and the variation value compensation is performed.
  • the government unit 220 adds (i.e., Data + ⁇ Vth + ⁇ V OLED ) to the image signal Data of each pixel circuit input through the input terminal and provides them to the corresponding pixel circuits to drive the organic light emitting display device, thereby causing luminance deviation.
  • the organic light emitting display device can be used as a display device having no deterioration in luminance and luminance unevenness despite deterioration due to prolonged use.

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Abstract

The present invention relates to a compensation apparatus, which compensates for a brightness deviation due to use of an organic light emitting display device for a long time, comprising: a driving transistor (112) having a first electrode, a second electrode and a gate electrode; a first voltage source (VDD) connected to the first electrode of the driving transistor (112); an organic electroluminescence device (114) having an anode electrode connected to the second electrode of the driving transistor (112); a second voltage source (Vss); a selection switch (115) for selectively connecting a cathode electrode of the organic electroluminescence device (114) between the second voltage source (Vss) and a current sink (160); and a current measurement circuit (140) for measuring the current flowing from the first voltage source (VDD) to the current sink (160) when a test voltage (Vdata) is applied to the gate electrode of the driving transistor (112).

Description

표시장치의 휘도 편차 보상장치 및 보상방법Luminance deviation compensation device and compensation method of display device
본 발명은 표시장치의 휘도 편차 보상장치 및 보상방법에 관한 것으로, 특히 표시장치의 화소용 표시소자로 유기전계 발광소자를 이용하는 유기전계발광 표시장치의 휘도 편차 보상장치 및 보상방법에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance deviation compensation device and a compensation method of a display device, and more particularly, to a luminance deviation compensation device and a compensation method of an organic light emitting display device using an organic light emitting device as a pixel display device of a display device.
최근 표시장치의 화소로 유기전계 발광소자(이하 「유기EL소자」라 한다)를 이용한 유기전계발광 표시장치(이하 간단하게 「유기발광 표시장치」라고 표기하는 경우도 있다)가 각광을 받고 있으며, 이 유기EL소자를 발광소자로서 이용하는 유기발광 표시장치는 경량, 박형이면서 다른 표시장치에 비해 휘도 특성 및 시야각 특성이 우수하여 차세대 평판 표시장치로서 주목받고 있다.Recently, an organic light emitting display device (hereinafter sometimes referred to simply as an organic light emitting display device) using an organic light emitting device (hereinafter referred to as an organic EL device) as a pixel of a display device has been in the spotlight. The organic light emitting display device using this organic EL element as a light emitting element is attracting attention as a next-generation flat panel display device because it is light and thin and has excellent luminance characteristics and viewing angle characteristics compared to other display devices.
유기EL소자는 유리 등의 투명한 기판상에 형성된 양극과 음극으로 이루어지는 한 쌍의 전극 사이에 유기화합물을 포함하는 유기발광 층을 삽입 형성한 구조를 가지며, 상기 한 쌍의 전극으로부터 유기발광 층에 정공(hole) 및 전자(electron)를 주입하여 재결합시킴으로써 여기자(exciton)를 생성시켜서, 이 여기자의 활성이 상실될 때의 광의 방출을 이용하여 표시 등을 하는 발광소자이다.The organic EL device has a structure in which an organic light emitting layer containing an organic compound is inserted between a pair of electrodes formed of a positive electrode and a negative electrode formed on a transparent substrate such as glass, and holes are formed in the organic light emitting layer from the pair of electrodes. It is a light emitting device that generates an exciton by injecting and recombining holes and electrons, and displays or the like by utilizing the emission of light when the activity of the excitons is lost.
상기 유기발광 층은 유기재료로 이루어지는 박막 층이며, 발광하는 광의 색 및 전류를 광으로 변환하는 변환효율은 유기발광 층을 형성하는 유기재료의 조성에 의해 결정되고, 서로 다른 유기재료는 서로 다른 색의 광을 발생시킨다.The organic light emitting layer is a thin film layer made of an organic material, the conversion efficiency of converting the color and current of light emitted into light is determined by the composition of the organic material forming the organic light emitting layer, different organic materials are different colors Generates light.
그러나 표시장치를 장시간 사용하면 이 유기재료가 열화하여 발광 시의 효율이 저하하며, 이에 의해 표시장치의 수명이 단축된다. 이때 예를 들어 발광하는 광의 색에 따라서 서로 다른 유기재료는 다른 속도로 열화할 가능성이 있고, 또, 색의 열화에도 차이가 발생한다.However, if the display device is used for a long time, the organic material deteriorates and the efficiency at the time of light emission is reduced, thereby shortening the lifetime of the display device. At this time, for example, different organic materials may deteriorate at different rates depending on the color of light emitted, and a difference also occurs in deterioration of color.
또, 표시장치를 구성하는 복수의 화소는 각각 다른 화소와 동일한 속도로 열화한다고는 할 수 없으며, 이 열화의 속도의 차이는 표시의 불 균일로 이어진다.In addition, the plurality of pixels constituting the display device cannot be deteriorated at the same speed as the other pixels, and the difference in the speed of the deterioration leads to uneven display.
이와 같은 열화의 원인으로는 먼저 표시장치의 장시간 사용에 따른 소자 자체의 저항값의 상승 및 발광효율의 저하를 들 수 있다. 유기EL소자는 장시간 발광하면 소자의 저항값이 서서히 증가하는 특성이 있고, 또, 표시장치를 구성하는 복수의 각 유기EL소자는 각각 발광빈도가 서로 다르므로 누적 발광시간도 서로 다를 수밖에 없다. 따라서 표시장치를 장시간 구동하면 각 유기EL소자 상호 간에 저항값의 편차가 발생하고, 이에 따라 발광 휘도의 편차가 발생하여 화면 전체의 휘도 무라(mura)나 고스트 이미지(ghost image)가 생긴다는 문제가 있다.The causes of such deterioration include an increase in the resistance value of the device itself and a decrease in luminous efficiency due to prolonged use of the display device. The organic EL element has a characteristic that the resistance value of the element gradually increases when it emits light for a long time, and since the organic EL elements constituting the display device have different light emission frequencies, the cumulative emission time is inevitably different. Therefore, when the display device is driven for a long time, a variation in resistance value occurs between the organic EL elements, and thus a variation in emission luminance occurs, resulting in a luminance mura or a ghost image of the entire screen. have.
열화의 다른 원인으로는 화소를 구성하는 박막 트랜지스터(TFT), 특히 구동 트랜지스터의 사용시간의 경과에 따른 열화에 의한 문턱 전압의 증가에 기인한 유기EL소자의 발광 광의 강도의 저하이며, 트랜지스터의 문턱 전압의 증가 역시 표시장치 내의 복수의 트랜지스터마다 다르다.Another cause of deterioration is a decrease in the intensity of the light emitted from the organic EL element due to an increase in the threshold voltage due to deterioration with the elapse of use time of the thin film transistor (TFT) constituting the pixel, especially the driving transistor, and the threshold of the transistor. The increase in voltage also varies among the plurality of transistors in the display device.
한편, 이와 같은 표시장치의 장시간 사용에 따른 열화의 문제를 해결하기 위한 기술로 특허문헌 1에 기재된 기술이 있다.On the other hand, there exists a technique of patent document 1 as a technique for solving the problem of deterioration by long time use of such a display apparatus.
도 1은 특허문헌 1의 표시장치 구동회로의 구성을 나타내는 회로도이다.1 is a circuit diagram showing a configuration of a display device driving circuit of Patent Document 1. FIG.
종래의 표시장치 구동회로는 도 1에 도시하는 것과 같이, 선택 트랜지스터(90)와 구동 트랜지스터(70) 및 유기EL소자(50)로 이루어지는 화소 회로(60)를 가지며, 제 1 전압 원(14)과, 제 1 전압 원(14)을 구동 트랜지스터(70)의 제 1 전극에 선택적으로 접속하는 제 1 스위치(S1)와, 구동 트랜지스터(70)의 제 2 전극에 애노드가 접속된 유기EL소자(50)와, 제 2 전압 원(15)과, 유기EL소자(50)의 캐소드를 제 2 전압 원(15)에 선택적으로 접속하는 제 2 스위치(S2)를 구비한다.The conventional display device driving circuit has a pixel circuit 60 composed of the selection transistor 90, the driving transistor 70, and the organic EL element 50, as shown in FIG. 1, and the first voltage source 14. A first switch S1 for selectively connecting the first voltage source 14 to the first electrode of the driving transistor 70, and an organic EL element having an anode connected to the second electrode of the driving transistor 70. 50, a second voltage source 15, and a second switch S2 for selectively connecting the cathode of the organic EL element 50 to the second voltage source 15.
또, 제 1 전극이 구동 트랜지스터(70)의 제 2 전극에 접속된 리드 아웃 트랜지스터(80)와, 전류 원(16)과, 전류 원(16)을 리드 아웃 트랜지스터(80)의 제 2 전극에 선택적으로 접속하는 제 3 스위치(S3)와, 전류 싱크(17)와, 전류 싱크(17)를 리드 아웃 트랜지스터(80)의 제 2 전극에 선택적으로 접속하는 제 4 스위치(S4)와, 구동 트랜지스터(70)의 게이트 전극에 시험전압을 인가한 때의 전압을 측정하기 위해 리드 아웃 트랜지스터(80)의 제 2 전극에 접속된 전압측정회로(18)를 포함한다.Further, the first electrode is connected to the second electrode of the drive transistor 70, the readout transistor 80, the current source 16, and the current source 16 to the second electrode of the readout transistor 80. A third switch S3 selectively connected, a current sink 17, a fourth switch S4 selectively connecting the current sink 17 to a second electrode of the readout transistor 80, and a driving transistor And a voltage measuring circuit 18 connected to the second electrode of the readout transistor 80 to measure the voltage when the test voltage is applied to the gate electrode of 70.
전압측정회로(18)는 측정한 전압 값을 디지털 신호로 변환하기 위한 A/D 컨버터(18a)와 프로세서(18b) 및 측정한 전압 값을 기억하는 메모리(18c)를 구비하고, 멀티플렉서(40)를 통해서 복수의 리드 아웃 트랜지스터(80)의 제 2 전극과 접속되어 화소 회로(60)로부터의 전압(Vout)을 순차 판독한다.The voltage measuring circuit 18 includes an A / D converter 18a for converting the measured voltage value into a digital signal, a processor 18b, and a memory 18c for storing the measured voltage value. Through the second electrode of the plurality of read out transistors 80, the voltage Vout from the pixel circuit 60 is sequentially read.
프로세서(18b)는 디지털 신호를 아날로그 신호로 변환하는 D/A 컨버터(18e)를 통해서 화소 회로(60)의 데이터 라인에 접속되어 미리 정해진 데이터 값을 데이터 라인에 제공한다. 또, 프로세서(18b)는 입력단자로부터 입력되는 표시데이터(Data)를 수신해서 후술하는 변화의 보상을 하며, 이에 의해 보상데이터를 데이터 라인에 제공한다.The processor 18b is connected to a data line of the pixel circuit 60 through a D / A converter 18e that converts a digital signal into an analog signal and provides a predetermined data value to the data line. In addition, the processor 18b receives the display data Data input from the input terminal and compensates for the change described later, thereby providing the compensation data to the data line.
다음에, 특허문헌 1의 표시장치의 특성변화를 보상하는 방법에 대해서 간략하게 설명한다.Next, the method of compensating for the characteristic change of the display device of Patent Document 1 will be briefly described.
먼저, 제 1 스위치(S1)와 제 4 스위치(S4)를 폐쇄하고, 제 2 스위치(S2) 및 제 3 스위치(S3)를 개방하여, 전압측정회로(18)를 이용해서 리드 아웃 트랜지스터(80)의 제 2 전극에서의 전압을 측정함으로써 구동 트랜지스터(70)의 특성을 나타내는 제 1 신호(V1)를 얻는다.First, the first switch S1 and the fourth switch S4 are closed, the second switch S2 and the third switch S3 are opened, and the readout transistor 80 is formed using the voltage measuring circuit 18. The first signal V1 indicating the characteristics of the driving transistor 70 is obtained by measuring the voltage at the second electrode of the transistor ().
도 1에서는 표시장치의 복수의 화소 중 하나의 화소만을 나타내고 있으나, 상기 제 1 신호는 표시장치를 구성하는 복수의 화소 전체에 대해서, 각각의 화소별로 측정한다.Although only one pixel of the plurality of pixels of the display device is shown in FIG. 1, the first signal is measured for each pixel of the entire plurality of pixels of the display device.
제 1 신호(V1)는 예를 들어 화소 회로(60)를 표시장치로서 사용하기 전, 즉 사용에 의해 구동 트랜지스터가 열화하기 전에 1회 측정하여, 이를 제 1 목표신호로 메모리(195)에 기억하고, 그 후, 미리 전해진 시간 동안 표시장치로 사용하여 열화한 후에 상기와 동일한 방법으로 제 1 신호를 측정하여, 이를 메모리(18c)에 기억한다.The first signal V1 is measured once before using the pixel circuit 60 as a display device, that is, before the driving transistor deteriorates by use, for example, and stores it as a first target signal in the memory 195. After that, after deterioration using the display device for a previously transmitted time, the first signal is measured in the same manner as described above and stored in the memory 18c.
다음에, 제 1 스위치(S1)와 제 4 스위치(S4)를 개방하고, 제 2 스위치(S2) 및 제 3 스위치(S3)를 폐쇄하여, 전압측정회로(18)를 이용해서 리드 아웃 트랜지스터(80)의 제 2 전극에서의 전압을 측정함으로써 유기EL소자(50)의 특성을 나타내는 제 2 신호(V2)를 얻는다.Next, the first switch S1 and the fourth switch S4 are opened, the second switch S2 and the third switch S3 are closed, and the readout transistor (using the voltage measuring circuit 18) is used. By measuring the voltage at the second electrode of 80, a second signal V2 indicating the characteristics of the organic EL element 50 is obtained.
상기 제 2 신호(V2)는 표시장치를 구성하는 복수의 화소 전체에 대해서, 각각의 화소별로 측정하며, 제 1 신호와 마찬가지로, 표시장치의 사용 전, 즉 사용에 의해 유기EL소자(50)가 열화하기 전과, 미리 전해진 시간 동안 표시장치로 사용하여 열화한 후에 각각 측정하여 메모리(18c)에 기억한다.The second signal V2 is measured for each pixel of all the pixels constituting the display device, and like the first signal, the organic EL element 50 is operated before or after the use of the display device. Before deterioration and after deterioration using the display device for a previously transmitted time, the respective measurements are stored in the memory 18c.
다음에, 제 1 신호의 변화와 제 2 신호의 변화를 이용하여 구동회로의 특성의 변화를 보상한다.Next, the change in the characteristics of the driving circuit is compensated for by using the change in the first signal and the change in the second signal.
그 외에도, 특허문헌 2에는 유기발광 표시장치의 각각의 유기EL소자의 1면의 전압을 감지하여 피드백 신호를 발생하는 트랜지스터를 포함하는 전압감지회로와 개개의 유기EL소자에 대해 보정신호를 계산하여 개개의 유기EL소자를 구동하는 데이터에 보정신호를 적용함으로써 각 유기EL소자의 출력 변화를 보상하는 표시장치가 기재되어 있다.In addition, Patent Literature 2 calculates a correction signal for each organic EL element and a voltage sensing circuit including a transistor for sensing a voltage on one surface of each organic EL element of the organic light emitting display and generating a feedback signal. DESCRIPTION OF RELATED ART The display apparatus which compensates the output change of each organic EL element by applying the correction signal to the data which drives each organic EL element is described.
그러나 특허문헌 1에서는 각 화소 회로의 구동 트랜지스터의 열화에 의한 특성의 변화를 나타내는 제 1 신호(V1)와 유기EL소자의 열화에 의한 특성변화를 나타내는 제 2 신호(V2)를 각각 별도로 측정하고 있으므로 표시장치의 사용에 따른 특성변화를 측정하기 위한 단계가 복잡하여 번거롭고, 측정에 필요로 하는 시간도 오래 걸린다.However, in Patent Literature 1, since the first signal V1 indicating the characteristic change due to the deterioration of the driving transistor of each pixel circuit and the second signal V2 indicating the characteristic change due to the deterioration of the organic EL element are measured separately, Steps for measuring the characteristic change according to the use of the display device are complicated and cumbersome, and it takes a long time for the measurement.
또, 상기 특성변화의 측정을 위해서는 각 화소별로 리드 아웃 트랜지스터를 필요로 하는 동시에, 제 1 내지 제 4 스위치의 4개의 스위치와 멀티플렉서(40) 및 별도의 전류 원을 필요로 하므로 표시장치의 사용에 따른 특성변화의 측정을 위한 회로 구성도 복잡하며, 이는 표시장치의 개구율 저하로 연결되어서, 결과적으로 표시장치의 휘도 저하로 이어진다는 문제가 있고, 특히 표시장치의 양방향으로 광을 방출하는 투명 유기전계발광 표시장치에서는 이 문제는 더 현저하다.In addition, the measurement of the characteristic change requires a readout transistor for each pixel, and requires four switches of the first to fourth switches, a multiplexer 40, and a separate current source. The circuit configuration for measuring the characteristic change is complicated, which leads to a decrease in the aperture ratio of the display device, resulting in a decrease in the brightness of the display device. In particular, a transparent organic field emitting light in both directions of the display device. This problem is more prominent in light emitting displays.
또, 특허문헌 2는 표시장치의 사용에 따른 특성 저하의 원인 중 하나인 구동 트랜지스터의 열화에 대해서는 고려하고 있지 않으므로, 표시장치의 장시간 사용에 따른 성능 저하의 문제를 완전하게 해결할 수는 없다.In addition, Patent Document 2 does not consider the deterioration of the driving transistor which is one of the causes of the deterioration of characteristics caused by the use of the display device, and thus cannot completely solve the problem of deterioration of performance caused by the long use of the display device.
또, 유기EL소자의 1면의 전압을 감지하여 피드백 신호를 발생하는 트랜지스터를 포함하는 전압감지회로를 별도로 구비하여야 하므로 역시 표시장치의 개구율 저하와 함께 휘도 저하로 이어진다는 문제가 있다.In addition, since a voltage sensing circuit including a transistor for sensing a voltage of one surface of the organic EL element and generating a feedback signal must be separately provided, there is a problem that the aperture ratio of the display device is lowered and the luminance is lowered.
<선행기술문헌><Preceding technical literature>
<특허문헌><Patent Documents>
특허문헌 1 : WO2009/002406호 공개 팸플릿Patent Document 1: WO2009 / 002406 Publication Pamphlet
특허문헌 2 : 일본 특표2007-514966호 공보Patent Document 2: Japanese Patent Application Laid-Open No. 2007-514966
본 발명은 상기 과제를 감안하여 이루어진 것으로, 구동 트랜지스터의 열화에 의한 특성변화와 유기EL소자의 열화에 의한 특성변화를 간단한 구성에 의해, 하나의 스텝에 의해 동시에 측정할 수 있으면서도 종래에 비해 특성변화를 측정하기 위한 회로 구성이 간단한 표시장치의 휘도 편차 보상장치 및 보상방법을 제공하는 것으로 목적으로 한다.SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and the characteristic change due to deterioration of the driving transistor and the characteristic change due to deterioration of the organic EL element can be simultaneously measured in one step with a simple configuration, but the characteristic change compared with the conventional art. It is an object of the present invention to provide a luminance deviation compensation device and a compensation method of a display device having a simple circuit configuration for measuring.
상기 과제를 해결하기 위한 본 발명의 표시장치의 휘도 편차 보상장치는, 유기발광 표시장치의 휘도 편차 보상장치로, 제 1 전극과 제 2 전극 및 게이트 전극을 갖는 구동 트랜지스터와, 상기 구동 트랜지스터의 상기 제 1 전극과 접속되는 제 1 전압 원과, 상기 구동 트랜지스터의 상기 제 2 전극에 애노드 전극이 접속된 유기전계 발광소자와, 제 2 전압 원과, 상기 유기전계 발광소자의 캐소드 전극을 상기 제 2 전압 원과 전류 싱크 사이에서 선택적으로 접속하는 선택 스위치와, 상기 구동 트랜지스터의 상기 게이트 전극에 시험전압이 인가된 때에 상기 제 1 전압 원으로부터 상기 전류 싱크로 흐르는 전류를 측정하는 전류측정회로를 포함한다.The luminance deviation compensation device of the display device of the present invention for solving the above problems is a luminance deviation compensation device of an organic light emitting display device, a driving transistor having a first electrode, a second electrode and a gate electrode, and the A second voltage source connected to a first electrode, an organic light emitting diode having an anode connected to the second electrode of the driving transistor, a second voltage source, and a cathode of the organic light emitting diode; And a selection switch for selectively connecting between a voltage source and a current sink, and a current measuring circuit for measuring a current flowing from the first voltage source to the current sink when a test voltage is applied to the gate electrode of the driving transistor.
다른 형태의 본 발명의 표시장치의 휘도 편차 보상장치는, n행 m열의 복수의 화소 회로와 제 1 전압 원 및 제 2 전압 원을 구비하는 유기발광 표시장치의 휘도 편차 보상장치로, 상기 복수의 화소 회로는 각각, 구동트랜지스터와, 일단 측이 상기 제 1 전압 원과 접속되어서, 상기 구동트랜지스터가 온 되면 상기 제 1 전압 원으로부터 전압을 인가받는 유기발광소자와, 상기 구동트랜지스터 오프 시에 선택적으로 온 되어서 상기 유기발광소자의 상기 일단 측에 전압을 인가하는 판독트랜지스터를 구비하며, 상기 휘도 편차 보상장치는, 전류 싱크와, 상기 유기발광소자의 타단 측을 상기 제 2 전압 원과 상기 전류 싱크 사이에서 선택적으로 접속하는 선택 스위치와, 상기 구동트랜지스터에 시험전압이 인가된 때에 상기 제 1 전압 원으로부터 상기 유기발광소자로 흐르는 전류를 측정하고, 상기 판독트랜지스터가 온 된 때에 상기 판독트랜지스터로부터 상기 유기발광소자로 흐르는 전류를 측정하는 전류측정회로를 포함한다.Another aspect of the present invention provides a luminance deviation compensating device of an organic light emitting display device including a plurality of pixel circuits in n rows and m columns, and a first voltage source and a second voltage source. Each of the pixel circuits includes a driving transistor, an organic light emitting element that receives a voltage from the first voltage source when the driving transistor is turned on, and is connected to the first voltage source once, and selectively when the driving transistor is turned off. And a read transistor configured to apply a voltage to the one end side of the organic light emitting element, wherein the luminance deviation compensator includes a current sink and a second end of the organic light emitting element between the second voltage source and the current sink. An organic light emission from the first voltage source when a test switch is applied to the driving transistor; Measured as the flowing current, and the time of the read transistor turned on and a current measuring circuit for measuring a current flowing to the organic light emitting element from the read transistor.
또, 과제를 해결하기 위한 본 발명의 표시장치의 휘도 편차 보상방법은, 상기 휘도 편차 보상장치에 의한 휘도 편차 보상방법으로, 상기 선택스위치를 상기 전류 싱크 측으로 전환하는 단계와, 상기 전류측정회로를 이용하여 상기 제 1 전압 원에서 상기 전류 싱크로 흐르는 전류를 측정하는 단계와, 측정된 상기 전류로부터 상기 유기발광 표시장치의 휘도 편차를 보상하는 단계를 포함한다.In addition, the luminance deviation compensation method of the display device of the present invention for solving the problem, the luminance deviation compensation method by the luminance deviation compensation device, the step of switching the selection switch to the current sink side, and the current measuring circuit And measuring a current flowing from the first voltage source to the current sink, and compensating for the luminance deviation of the organic light emitting display device from the measured current.
또, 다른 형태의 본 발명의 표시장치의 휘도 편차 보상방법은, 상기 다른 형태의 휘도 편차 보상장치에 의한 휘도 편차 보상방법으로, 상기 유기발광 표시장치의 사용에 따른 특성이 열화하기 전의 상기 복수의 화소 회로 각각의 구동트랜지스터의 게이트 소스 간 전압 및 유기발광소자의 구동전압을 측정하는 제 3 단계와, 상기 유기발광 표시장치의 사용에 따른 특성이 열화한 후의 상기 복수의 화소 회로 각각의 구동트랜지스터의 게이트 소스 간 전압 및 유기발광소자의 구동전압을 측정하는 제 4 단계와, 상기 제 3 단계와 상기 제 4 단계에서 각각 측정한 상기 복수의 화소 회로 각각의 구동트랜지스터의 게이트 소스 간 전압 및 유기발광소자의 구동전압으로부터 복수의 화소 회로 각각의 구동트랜지스터의 문턱 전압 변동치 및 유기발광소자의 구동전압 변동치를 산출하는 제 5 단계를 포함한다.The luminance deviation compensation method of the display device of another embodiment of the present invention is a luminance deviation compensation method using the brightness deviation compensation device of another embodiment, wherein the plurality of the plurality of the plurality of the plurality of the light emitting diodes before the characteristics of the organic light emitting display device deteriorate. A third step of measuring the voltage between the gate sources of the driving transistors of the pixel circuits and the driving voltages of the organic light emitting diodes, and after the characteristics of the organic light emitting display are deteriorated, the driving transistors of each of the plurality of pixel circuits A fourth step of measuring the voltage between the gate sources and the driving voltage of the organic light emitting diode, and the voltage between the gate sources of the driving transistors of each of the plurality of pixel circuits measured in the third and fourth steps, and the organic light emitting diode Threshold Voltage Fluctuations of the Driving Transistors of Each of the Pixel Circuits from the Driving Voltages of the Pixel Circuits and the Driving of the OLEDs A fifth step for calculating the pressure fluctuation.
본 발명은 구동 트랜지스터의 열화에 의한 특성의 변화와 유기EL소자의 열화에 의한 특성변화를 1회의 전류 측정으로 동시에 판단할 수 있으므로 표시장치의 사용에 따른 특성변화를 측정하기 위한 단계가 간단한 동시에 측정에 필요로 하는 시간도 단축할 수 있다.In the present invention, since the change of the characteristic due to the deterioration of the driving transistor and the characteristic change due to the deterioration of the organic EL device can be judged simultaneously by one current measurement, the steps for measuring the characteristic change according to the use of the display device are simple and simultaneously measured. The time required for this can also be shortened.
또, 본 발명은 표시장치의 각 화소 회로의 공통 캐소드를 제 2 전압 원 또는 전류 싱크 사이에서 선택적으로 접속하는 선택스위치에 의해 간단하게 측정 모드로 전환이 가능하므로, 표시장치의 특성변화의 측정을 위한 회로 구성이 간단하며, 따라서 특성변화의 측정을 위한 실질적인 추가 구성이 불필요하므로, 개구율의 실질적인 저하 없이도 간단하게 표시장치의 특성변화 측정을 위한 구성의 구축이 가능하다.In addition, the present invention can be easily switched to the measurement mode by a selection switch that selectively connects the common cathode of each pixel circuit of the display device between the second voltage source or the current sink, so that the measurement of the characteristic change of the display device can be measured. Since the circuit configuration is simple, and therefore, a substantial additional configuration for measuring the characteristic change is unnecessary, it is possible to simply construct a configuration for measuring the characteristic change of the display device without substantially reducing the aperture ratio.
도 1은 종래의 표시장치 구동회로의 구성을 나타내는 회로도,1 is a circuit diagram showing a configuration of a conventional display device driving circuit;
도 2는 본 발명의 바람직한 실시형태 1의 표시장치의 구성을 개략적으로 나타내는 회로도,FIG. 2 is a circuit diagram schematically showing the configuration of a display device of preferred embodiment 1 of the present invention; FIG.
도 3은 본 발명의 바람직한 실시형태 1의 특정 화소 회로 및 휘도 편차 보상장치의 중요 구성을 나타내는 회로도,3 is a circuit diagram showing important configurations of a specific pixel circuit and a luminance deviation compensating device of preferred embodiment 1 of the present invention;
도 4는 본 발명의 바람직한 실시형태 1의 휘도 편차 보정방법의 흐름을 나타내는 플로차트,4 is a flowchart showing the flow of the luminance deviation correction method of Embodiment 1 of the present invention;
도 5는 본 발명의 바람직한 실시형태 2의 표시장치의 구성을 개략적으로 나타내는 회로도,5 is a circuit diagram schematically showing the configuration of a display device according to a second preferred embodiment of the present invention;
도 6은 본 발명의 바람직한 실시형태 2의 특정 화소 회로 및 휘도 편차 보상장치의 중요 구성을 나타내는 회로도,6 is a circuit diagram showing important configurations of a specific pixel circuit and a luminance deviation compensating device of preferred embodiment 2 of the present invention;
도 7은 본 발명의 바람직한 실시형태 2의 휘도 편차 보상방법의 흐름을 나타내는 플로차트,7 is a flowchart showing the flow of the luminance deviation compensation method of the second preferred embodiment of the present invention;
도 8은 본 발명의 바람직한 실시형태 2의 표시장치 열화 전의 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하는 방법의 흐름을 나타내는 플로차트,8 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element before the display device deterioration of the preferred embodiment 2 of the present invention;
도 9는 본 발명의 바람직한 실시형태 2의 표시장치 열화 후의 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하는 방법의 흐름을 나타내는 플로차트이다.Fig. 9 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element after the display device deterioration of the preferred embodiment 2 of the present invention.
이하, 본 발명의 바람직한 실시형태에 대해서 도면을 참조하면서 상세하게 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described in detail, referring drawings.
1. 실시형태 11. Embodiment 1
도 2는 본 발명의 바람직한 실시형태 1의 표시장치의 구성을 개략적으로 나타내는 회로도이다.2 is a circuit diagram schematically showing the configuration of a display device of preferred embodiment 1 of the present invention.
본 실시형태 1의 표시장치는 도 2에 도시하는 것과 같이 표시부(100), 컨트롤러(120), 게이트 드라이버(130), 데이터 드라이버(150), 애노드 드라이버(170), 선택스위치(115), 전류 싱크(160), A/D컨버터(142) 및 D/A컨버터(145)를 포함한다.As shown in FIG. 2, the display device of the first embodiment includes the display unit 100, the controller 120, the gate driver 130, the data driver 150, the anode driver 170, the selection switch 115, and a current. A sink 160, an A / D converter 142, and a D / A converter 145 are included.
표시부(100)는 각각 평행하게 배치된 복수의 게이트 라인(Lg1~Lgn)(n은 2 이상의 정수)과 복수의 데이터 라인(Ld1~m)(m은 2 이상의 정수) 및 복수의 애노드 라인(La1~n)를 구비하고 있고, 복수의 게이트 라인(Lg1~n)과 복수의 애노드 라인(La1~n)은 서로 평행하게 배열되어 있다. 또, 복수의 데이터 라인(Ld1~m)은 복수의 게이트 라인(Lg1~n) 및 복수의 애노드 라인(La1~n)과 서로 교차하고 있다.The display unit 100 includes a plurality of gate lines Lg1 to Lgn (n is an integer of 2 or more), a plurality of data lines Ld1 to m (m is an integer of 2 or more), and a plurality of anode lines La1, which are respectively disposed in parallel. n, and the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n are arranged in parallel with each other. The plurality of data lines Ld1 to m intersect with the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n.
복수의 게이트 라인(Lg1~n)과 복수의 데이터 라인(Ld1~m)이 교차하는 각 교차지점에는 각각 화소 회로(Px(i,j))(i=1~n, j=1~m, m, n은 각각 자연수)가 배치되며, 복수의 화소 회로(P(i,j))는 n행 m열(m, n은 각각 자연수)의 매트릭스 형상으로 배열되어서 표시부(100)를 형성한다.At each intersection where the plurality of gate lines Lg1 to n and the plurality of data lines Ld1 to m cross each other, each of the pixel circuits Px (i, j) (i = 1 to n, j = 1 to m, m and n are natural numbers, respectively, and the plurality of pixel circuits P (i, j) are arranged in a matrix form of n rows and m columns (m and n are natural numbers, respectively) to form the display unit 100.
각 화소 회로(P(i,j))의 세부 구성에 대해서는 후술한다.The detailed structure of each pixel circuit P (i, j) is mentioned later.
표시부(100)의 복수의 화소 회로(P(i,j))는 각각 게이트 라인(Lg1~n)을 통해서 게이트 드라이버(130)에 접속되고, 또, 데이터 라인(Ld1~m)을 통해서 데이터 드라이버(150)와 접속되며, 애노드 라인(La1~n)을 통해서 애노드 드라이버(170)와 접속된다.The plurality of pixel circuits P (i, j) of the display unit 100 are connected to the gate driver 130 through the gate lines Lg1 to n, respectively, and the data driver through the data lines Ld1 to m. It is connected to the 150, and is connected to the anode driver 170 via the anode line (La1 ~ n).
컨트롤러(120)는 입력되는 화상 신호(Data)에 따라서 표시부(100)를 구동하는 게이트 신호와 데이터 신호를 생성하며, 게이트 신호는 게이트 드라이버(130)에 공급되고, 데이터 신호는 데이터 드라이버(150)에 공급된다.The controller 120 generates a gate signal and a data signal for driving the display unit 100 according to the input image signal Data, the gate signal is supplied to the gate driver 130, and the data signal is the data driver 150. Supplied to.
게이트 드라이버(130)는 게이트 라인(Lg1~n)에 접속되며, 게이트 신호에 따른 게이트 펄스를 각각의 게이트 라인(Lg1~n)에 소정의 순서로 공급한다.The gate driver 130 is connected to the gate lines Lg1 to n, and supplies gate pulses corresponding to the gate signals to the respective gate lines Lg1 to n in a predetermined order.
데이터 드라이버(150)는 데이터 라인(Ld1~m)에 접속되며, 이 데이터 라인(Ld1~m)을 통해서 게이트 신호가 공급되는 게이트 라인(Lg1~n) 상에 위치하는 화소 회로(P(i,j)) 중에서 발광 구동할 화소에 대해 데이터 신호를 공급한다.The data driver 150 is connected to the data lines Ld1 to m, and is located on the pixel circuits P (i, which are located on the gate lines Lg1 to n through which the gate signals are supplied through the data lines Ld1 to m. j)), a data signal is supplied to the pixel to drive light emission.
애노드 드라이버(170)는 애노드 라인(La1~n)를 통해서 화소 회로(P(i,j))에 전압 VHigh 또는 VLow의 전압신호를 출력한다. 전압 VLow는 기입 처리시에 각 화소 회로(P(i,j))의 유기EL소자(114)를 비 발광상태로 하기 위한 전압이고, 또, 전압 VHigh는 각 화소 회로(P(i,j))의 유기EL소자(114)를 발광상태로 하기 위한 전압이다.The anode driver 170 outputs a voltage signal having a voltage V High or V Low to the pixel circuit P (i, j) through the anode lines La1 to n. The voltage V Low is a voltage for turning the organic EL element 114 of each pixel circuit P (i, j) into a non-light emitting state during the writing process, and the voltage V High is the pixel circuit P (i, j) is a voltage for causing the organic EL element 114 to emit light.
그러나 필요에 따라서는 애노드 드라이버(13)를 별도로 설치하지 않고, 복수의 화소 회로(P(i,j))의 애노드 라인(La1~n)에 대해 동시에 애노드 전압을 인가하는 이른바 공통 애노드(common anode)로 해도 좋다.However, if necessary, a common anode for simultaneously applying anode voltages to the anode lines La1 to n of the plurality of pixel circuits P (i, j) without separately installing the anode driver 13 is provided. ) May be used.
선택스위치(115)는 후술하는 화소 회로(P(i,j))의 유기EL소자(114)의 캐소드 측과 전류 싱크(160) 또는 제 2 전압 원(Vss) 사이를 선택적으로 접속하며, 후술하는 본 발명의 휘도 편차 측정시에는 각 유기EL소자(114)의 캐소드를 전류 싱크(160) 측과 연결하고, 통상의 표시장치로서 동작시에는 각 유기EL소자(114)의 캐소드를 제 2 전압 원(Vss)과 연결하며, 이 동작은 컨트롤러(120)의 제어 하에 이루어질 수 있다.The selection switch 115 selectively connects between the cathode side of the organic EL element 114 of the pixel circuit P (i, j), which will be described later, and the current sink 160 or the second voltage source Vss. In the luminance deviation measurement of the present invention, the cathode of each organic EL element 114 is connected to the current sink 160 side, and when operating as a normal display device, the cathode of each organic EL element 114 is connected to the second voltage. In connection with the circle Vss, this operation may be performed under the control of the controller 120.
전류 싱크(160)는 일단이 선택스위치(115)와 접속되고 타단은 A/D컨버터(142)를 통해서 컨트롤러(120)와 접속되며, 선택스위치(115)에 의해 화소 회로(P(i,j))의 유기EL소자(114)의 캐소드와 접속된 때에 미리 정해진 데이터 값이 데이터 라인(Ldj)에 인가되면 미리 정해진 일정 값의 전류를 흘린다. 전류측정회로(140)에 대해서는 후술한다.One end of the current sink 160 is connected to the selection switch 115, and the other end thereof is connected to the controller 120 through the A / D converter 142 and the pixel circuit P (i, j) by the selection switch 115. When a predetermined data value is applied to the data line Ldj when connected to the cathode of the organic EL element 114), a current of a predetermined constant value flows. The current measuring circuit 140 will be described later.
다음에, 화소 회로(P(i,j))의 상세한 구성 및 휘도 편차 보상장치에 대해서 설명한다. 도 3은 본 발명의 바람직한 실시형태 1의 화소 회로 및 휘도 편차 보상장치의 주요 구성을 나타내는 회로도이다.Next, the detailed configuration of the pixel circuit P (i, j) and the luminance deviation compensator will be described. Fig. 3 is a circuit diagram showing the main configuration of the pixel circuit and the luminance deviation compensating device of preferred embodiment 1 of the present invention.
본 실시형태 1의 화소 회로(P(i,j))는 도 3에 도시하는 것과 같이 유기EL소자(114)와 구동 트랜지스터(112)와 스위칭 트랜지스터(111) 및 커패시터(113)를 포함한다.The pixel circuit P (i, j) of the first embodiment includes an organic EL element 114, a driving transistor 112, a switching transistor 111, and a capacitor 113 as shown in FIG.
각 트랜지스터(111, 112)는 제 1 전극과 제 2 전극 및 게이트 전극을 갖는다.Each transistor 111 and 112 has a first electrode, a second electrode and a gate electrode.
각 화소 회로(P(i,j))의 구동 트랜지스터(112)의 제 1 전극은 제 1 전압 원(VDD) 및 커패시터(113)의 타단과 접속되며, 여기서 제 1 전압 원(VDD)은 별도의 애노드 드라이버(170)를 갖는 표시장치에서는 애노드 드라이버(170)를 통해서 공급되는 전압 원일 수 있고, 복수의 화소 회로(P(i,j))의 애노드 라인(La1~n)에 대해 동시에 애노드 전압을 인가하는 이른바 공통 애노드인 경우에는 공통 애노드용 전압 원일 수 있다.The first electrode of the driving transistor 112 of each pixel circuit P (i, j) is connected to the other end of the first voltage source VDD and the capacitor 113, where the first voltage source VDD is separately provided. The display device having the anode driver 170 may be a voltage source supplied through the anode driver 170, and the anode voltage is simultaneously applied to the anode lines La1 to n of the plurality of pixel circuits P (i, j). In the case of a so-called common anode to which is applied, it may be a voltage source for a common anode.
또, 구동 트랜지스터(112)의 제 2 전극은 유기EL소자(114)의 애노드와 접속되고, 유기EL소자(114)의 캐소드는 선택스위치(115)를 통해서 제 2 전압 원(Vss) 또는 전류 싱크(160)와 선택적으로 접속된다. 또, 구동 트랜지스터(112)의 게이트 전극은 스위칭 트랜지스터(111)에 접속되며, 데이터 라인(Ldj)을 통해 공급되는 데이터를 선택적으로 구동 트랜지스터(112)에 제공한다.In addition, the second electrode of the driving transistor 112 is connected to the anode of the organic EL element 114, and the cathode of the organic EL element 114 is connected to the second voltage source Vss or current sink through the selection switch 115. And selectively connected to 160. In addition, the gate electrode of the driving transistor 112 is connected to the switching transistor 111, and selectively provides data supplied through the data line Ldj to the driving transistor 112.
스위칭 트랜지스터(111)의 게이트 전극은 게이트 라인(Lgi)을 통해서 게이트 드라이버(130)와 접속되고, 제 1 전극은 게이트 드라이버(130)로부터 공급되는 주사 신호(행 선택신호)에 의해 온(on) 하여 각각 데이터 라인(Ldj)에 입력된 화상신호(Data)를 구동 트랜지스터(112)의 게이트 전극 및 커패시터(113)의 일단에 출력한다.The gate electrode of the switching transistor 111 is connected to the gate driver 130 through a gate line Lgi, and the first electrode is turned on by a scan signal (row selection signal) supplied from the gate driver 130. The image signal Data input to the data line Ldj is output to the gate electrode of the driving transistor 112 and one end of the capacitor 113.
선택스위치(115)는 유기EL소자(114)의 캐소드를 제 2 전압 원(Vss)과 전류 싱크(160) 사이에서 선택적으로 접속하며, 통상의 표시소자로서 동작하는 경우에는 유기EL소자(114)의 캐소드와 제 2 전압 원(Vss)을 접속상태로 하고, 본 발명의 휘도 편차 측정시에는 유기EL소자(114)의 캐소드와 전류 싱크(160)를 접속상태로 한다.The selection switch 115 selectively connects the cathode of the organic EL element 114 between the second voltage source Vss and the current sink 160, and in the case of operating as a normal display element, the organic EL element 114 The cathode and the second voltage source Vss are connected to each other, and the cathode and the current sink 160 of the organic EL element 114 are connected to each other when measuring the luminance deviation of the present invention.
도 2에 도시하는 것과 같이 본 실시형태 1의 표시장치에서는 n행 m열의 복수의 화소 회로(P(i,j))의 캐소드가 서로 연결된 이른바 공통 캐소드(common cathod)이며, 공통 캐소드는 1개의 선택스위치(115)를 통해서 1개의 제 2 전압 원(Vss)과 접속된다.As shown in FIG. 2, in the display device of the first embodiment, a cathode of a plurality of pixel circuits P (i, j) in n rows and m columns is connected to each other, and a common cathode is one common cathode. It is connected to one second voltage source Vss through the selection switch 115.
전류측정회로(140)는 전류 측정값을 디지털 신호로 변환하기 위한 A/D컨버터(142)와 컨트롤러(120) 및 프로세서(141)를 구비하며, A/D컨버터(142)로부터의 디지털 신호는 프로세서(141)로 전송된다.The current measuring circuit 140 includes an A / D converter 142, a controller 120, and a processor 141 for converting a current measurement value into a digital signal, and the digital signal from the A / D converter 142 is Transmitted to the processor 141.
또, 전류측정회로(140)는 전류 측정값을 기억하기 위한 메모리(144)를 더 구비하며, 필요에 따라서는 로패스 필터(143)도 구비할 수 있다.The current measuring circuit 140 further includes a memory 144 for storing the current measured value, and a low pass filter 143 as necessary.
전류측정회로(140)는 전류 싱크(160) 및 선택스위치(115)를 통해서 표시부(100)의 복수의 화소 회로(P(i,j))의 공통 캐소드와 선택적으로 연결되며, 복수의 화소 회로(P(i,j)) 각각에 흐르는 전류를 순차 판독한다.The current measuring circuit 140 is selectively connected to the common cathode of the plurality of pixel circuits P (i, j) of the display unit 100 through the current sink 160 and the selection switch 115, and the plurality of pixel circuits. The current flowing through each of (P (i, j)) is sequentially read.
또, 프로세서(141)는 D/A컨버터(145)를 통해서 데이터 라인(Ldj)에 접속되며, 본 발명의 휘도 편차 측정시에 미리 정해진 데이터 값을 데이터 라인(Ldj)을 통해서 공급한다.In addition, the processor 141 is connected to the data line Ldj via the D / A converter 145, and supplies a predetermined data value through the data line Ldj at the time of measuring the luminance deviation of the present invention.
그리고 프로세서(141)는 입력단을 통해서 화상 신호(Data)를 수신하여 후술하는 휘도 보상을 하며, 이에 의해 통상의 표시장치로서 동작 시에 보상 데이터를 데이터 라인(Ldj)을 통해 화소 회로(P(i,j))에 제공한다.The processor 141 receives the image signal Data through the input terminal and compensates for the luminance described below. Thus, when operating as a normal display device, the compensation data is transmitted through the pixel circuit P (i) through the data line Ldj. , j)).
도 2에 도시한 표시장치는 컨트롤러(120)가 전류측정회로(140)의 프로세서(141)의 기능을 겸하는 것으로 하고 있으나, 이에 한정되지는 않으며, 컨트롤러(120)와는 별도의 구성으로 해도 좋다.In the display device shown in FIG. 2, the controller 120 also functions as the processor 141 of the current measurement circuit 140. However, the present invention is not limited thereto, and the display device may be configured separately from the controller 120.
다음에, 본 실시형태 1의 동작 설명에 앞서 본 실시형태의 휘도 편차 보상의 개념에 대해서 설명한다.Next, the concept of the luminance deviation compensation of the present embodiment will be described before explaining the operation of the first embodiment.
앞에서도 설명한 것과 같이, 유기발광 표시장치의 사용에 따른 휘도 저하의 원인으로는 각 화소 회로를 구성하는 구동 트랜지스터의 열화에 따른 문턱 전압의 상승과 유기EL소자의 내부 저항의 변화에 따른 전압의 변화를 들 수 있다.As described above, the cause of the decrease in luminance due to the use of the organic light emitting display device is that the threshold voltage is increased due to the deterioration of the driving transistors constituting each pixel circuit and the voltage is changed due to the change in the internal resistance of the organic EL element. Can be mentioned.
유기발광 표시장치의 휘도는 유기발광 표시장치의 각 화소 회로에 흐르는 전류량과 관계를 가지며, 구동 트랜지스터의 문턱 전압의 상승과 유기EL소자의 내부 저항의 변화에 따른 전압의 변화를 일괄 보상하여, 유기발광 표시장치의 각 화소 회로에 흐르는 전류량을 적정 휘도의 유지에 적절한 값으로 조절하면 장시간 사용에 따른 휘도 저하를 보상할 수 있다는 것이 본 발명의 기본 생각이다.The luminance of the organic light emitting diode display is related to the amount of current flowing through each pixel circuit of the organic light emitting diode display, and is compensated for by collectively compensating the voltage change due to the increase of the threshold voltage of the driving transistor and the change of the internal resistance of the organic EL element. The basic idea of the present invention is to adjust the amount of current flowing through each pixel circuit of the light emitting display device to a value suitable for maintaining appropriate luminance, thereby compensating for a decrease in luminance due to prolonged use.
또, 유기발광 표시장치에서는 복수의 화소 회로 각각의 발광빈도 또는 각 화소 회로의 유기발광 층 재료의 차이 등에 따라서 화소 회로 각각의 휘도 저하의 정도에 차이가 발생하므로, 전류량의 조절에 의한 휘도 편차의 보상은 복수의 화소 회로 각각에 대해 개별적으로 이루어져야 한다.Further, in the organic light emitting display device, a difference occurs in the degree of deterioration of the luminance of each pixel circuit according to the emission frequency of each of the plurality of pixel circuits or the difference in the organic light emitting layer material of each pixel circuit. Compensation must be made separately for each of the plurality of pixel circuits.
또, 유기발광 표시장치의 각 화소 회로에 흐르는 전류량의 조절을 위해서는 표시장치의 사용에 따른 열화 전에, 예를 들어 유기발광 표시장치를 표시장치로서 사용하기 전에 각 화소 회로에 흐르는 전류 값을 측정하여 이 측정한 전류 값을 기준 전류 값으로 하고, 일정 시간 사용에 의해 표시장치가 열화한 후에 각 화소 회로에 흐르는 전류 값을 측정하여, 기준 전류 값을 기초로 하여 열화 후의 측정값을 보상하도록 한다.In addition, in order to adjust the amount of current flowing through each pixel circuit of the organic light emitting display device, the current value flowing through each pixel circuit is measured before deterioration due to the use of the display device, for example, before the organic light emitting display device is used as the display device. This measured current value is referred to as the reference current value, and the current value flowing through each pixel circuit is measured after the display device deteriorates by use for a predetermined time, so as to compensate the measured value after degradation based on the reference current value.
이어서, 본 발명의 동작에 대해서 설명한다. 도 4는 본 발명의 바람직한 실시형태 1의 휘도 편차 보정방법의 흐름을 나타내는 플로차트이다.Next, the operation of the present invention will be described. 4 is a flowchart showing the flow of the luminance deviation correction method according to the first preferred embodiment of the present invention.
먼저, 선택스위치(115)를 전류 싱크(160) 측으로 전환한 후(단계 S11), 데이터 라인(Ldj)에 미리 정해진 시험전압(Vdata)을 인가하고(단계 S12), 선택된 게이트 라인(Lgi)을 활성화한다(단계 S13).First, the selector switch 115 is switched to the current sink 160 side (step S11), and then a predetermined test voltage Vdata is applied to the data line Ldj (step S12), and the selected gate line Lgi is turned on. Activate (step S13).
여기서, 단계 S12 및 단계 S13은 그 순서가 역이 되어도 좋다. 즉, 선택된 게이트 라인(Lgi)을 활성화한 후 데이터 라인(Ldj)에 미리 정해진 시험전압(Vdata)을 인가해도 좋으며, 실제의 경우 이 두 단계는 서로 동기화되어 이루어진다.Here, the order of steps S12 and S13 may be reversed. That is, after activating the selected gate line Lgi, the predetermined test voltage Vdata may be applied to the data line Ldj. In practice, these two steps are synchronized with each other.
이에 의해 화소 회로(P(i,j))의 스위칭 트랜지스터(111)가 온 되어서 게이트 라인(Lgi)에 인가되는 시험전압(Vdata)을 구동 트랜지스터(112)의 게이트 전극 및 커패시터(113)의 일단에 출력한다.As a result, the switching transistor 111 of the pixel circuit P (i, j) is turned on and the test voltage Vdata applied to the gate line Lgi is applied to one end of the gate electrode and the capacitor 113 of the driving transistor 112. Output to.
이어서 제 1 전압 원(VDD)으로부터 애노드 전압을 인가하면(단계 S14) 전류는 제 1 전압 원(VDD)으로부터 구동 트랜지스터(112) 및 유기EL소자(114)를 통해서 전류 싱크(160)로 흐르며, 전류측정회로(140)에 의해 이 전류, 즉 화소 회로(P(i,j))를 흐르는 전류를 측정하여 측정한 전류 값을 메모리(144)에 기억한다(단계 S15).Subsequently, when an anode voltage is applied from the first voltage source VDD (step S14), current flows from the first voltage source VDD through the driving transistor 112 and the organic EL element 114 to the current sink 160. The current measurement circuit 140 measures this current, that is, the current flowing through the pixel circuit P (i, j), and stores the measured current value in the memory 144 (step S15).
여기서, 예를 들어 표시부(100)가 n행 m열의 복수의 화소 회로를 갖는 경우, 화소 회로를 흐르는 전류의 측정은 복수의 화소 회로 각각에 대해 모두 이루어져야 하며, 따라서 단계 S16에서는 측정할 화소 회로가 남아 있는가 여부를 판단한다.Here, for example, when the display unit 100 has a plurality of pixel circuits in n rows and m columns, the measurement of the current flowing through the pixel circuits must be made for each of the plurality of pixel circuits, so that the pixel circuit to be measured is determined in step S16. Determine if it remains.
단계 S16에서 화소 회로를 흐르는 전류 값을 측정할 화소 회로가 더 남아 있는 것으로 판단되면(단계 S16=Yes) 단계 S12로 복귀하여 단계 S12 내지 단계 S16을 반복하고, 단계 S16에서 화소 회로를 흐르는 전류 값을 측정할 화소 회로가 더 이상 남아 있지 않은 것으로 판단되면(단계 S16=No) 단계 S17으로 진행한다.If it is determined in step S16 that there are still more pixel circuits to measure the current value flowing through the pixel circuit (step S16 = Yes), the process returns to step S12 to repeat steps S12 to S16, and in step S16 the current value flowing through the pixel circuit. If it is determined that there are no more pixel circuits to be measured (step S16 = No), the flow proceeds to step S17.
n행 m 열의 복수의 화소 회로 각각에 대해 각 화소 회로에 흐르는 전류 값을 측정하는 방법으로는 n행 m 열의 복수의 화소 회로의 행 단위로 순차 측정하는 방법, 열 단위로 순차 측정하는 방법이 있을 수 있다.As a method of measuring a current value flowing in each pixel circuit for each of the plurality of pixel circuits in the n-row m column, there may be a method of sequentially measuring the rows of the plurality of pixel circuits in the n-row m column, or a method of sequentially measuring the columns. Can be.
행 단위로 순차 전류 값을 측정하는 경우에는, 도 2에서 예를 들어 먼저 게이트 라인(Lg1)을 활성화한 상태에서 순차 화소 회로(P(1,1)), 화소 회로(P(1,2)), …, 화소 회로(P(1,m))의 각 데이터 라인(Ld1), 데이터 라인(Ld2), …, 데이터 라인(Ldm)에 순차 시험전압(Vdata)을 인가하여 제 1 행째의 화소 회로 각각에 흐르는 전류 값을 측정하고, 이어서 제 2 행째의 화소 회로, 제 3 행째, …, 제 n 행째의 화소 회로에 대해 순차적으로 각 화소 회로에 흐르는 전류 값을 상기와 동일한 방법으로 측정할 수 있다.In the case of measuring the sequential current value in units of rows, for example, the sequential pixel circuits P (1,1) and the pixel circuits P (1,2) with the gate line Lg1 activated first, for example in FIG. 2. ),… , Each data line Ld1, data line Ld2,... Of the pixel circuit P (1, m). The test voltage Vdata is sequentially applied to the data line Ldm to measure the current value flowing through each of the pixel circuits of the first row, and then the pixel circuits of the second row, the third row,. For the n-th pixel circuit, the current value flowing through each pixel circuit can be measured in the same manner as described above.
다른 방법으로, 열 단위로 순차 전류 값을 측정하는 경우에는, 도 2에서 예를 들어 먼저 데이터 라인(Ld1)에 시험전압(Vdata)을 인가한 상태에서 순차 화소 회로(P(1,1)), 화소 회로(P(2,1)), …, 화소 회로(P(n,1))의 각 게이트 라인(Lg1), 게이트 라인(Lg2), …, 게이트 라인(Lgn)에 순차 게이트 신호를 인가함으로써 활성화시켜서 제 1 열째의 화소 회로 각각에 흐르는 전류를 측정하고, 이어서 제 2 열째, 제 3 열째, …, 제 n 열째의 화소 회로에 대해 순차적으로 각 화소 회로에 흐르는 전류 값을 상기와 동일한 방법으로 측정해도 좋다.Alternatively, in the case where the sequential current values are measured in units of columns, the sequential pixel circuits P (1, 1), for example, in the state in which the test voltage Vdata is first applied to the data line Ld1, for example in FIG. 2. , Pixel circuits P (2, 1),... Gate lines Lg1, gate lines Lg2 of the pixel circuit P (n, 1),... It activates by applying a sequential gate signal to the gate line Lgn, and measures the electric current which flows in each pixel circuit of a 1st column, and then the 2nd, 3rd, ... For the pixel circuit of the nth column, the current value flowing through each pixel circuit may be measured in the same manner as described above.
또, 상기 설명에서는 제 1행 제 1 열의 화소 회로(P(1,1))부터 시작하여 제 n 행 제 m 열의 화소 회로(P(n,m))에서 종료하는 것으로 설명하였으나, 이에 한정되는 것은 아니며, n행 m 열의 복수의 화소 회로 중 어느 화소 회로부터 시작해도 상관없다. 중요한 점은 n행 m 열의 복수의 화소 회로 모두에 대해서 각 화소 회로에 흐르는 전류 값을 측정하여 기억하면 된다.In the above description, it has been described that the pixel circuits P (1,1) in the first row and the first column start at the pixel circuits P (n, m) in the nth row m columns, but the present invention is not limited thereto. It is not necessary to start from any pixel circuit among the plurality of pixel circuits in n rows m columns. It is important to measure and store the current value flowing through each pixel circuit for all the plurality of pixel circuits in n rows m columns.
한편, 앞에서도 언급한 것과 같이, 유기발광 표시장치의 장시간의 사용에 따른 휘도 편차의 보상을 위한 각 화소 회로에 흐르는 전류 값의 측정은 유기발광 표시장치의 사용 전, 즉 열화 전에 1차로 측정하고, 이 1차 측정한 값을 목표전류 값으로서 기억하며, 그 후, 미리 정해진 일정 시간 사용 후, 즉 열화 후에 상기 열화 전의 측정방법과 동일한 방법으로 측정하여 기억할 필요가 있다.On the other hand, as mentioned above, the measurement of the current value flowing in each pixel circuit for compensation of the luminance deviation according to the long time use of the organic light emitting display device is measured first before use, that is, before deterioration of the organic light emitting display device. This primary measured value is stored as a target current value, and then it is necessary to measure and store it after the predetermined time of use, i.e., after deterioration, in the same manner as the measurement method before deterioration.
이 경우 상기 시험전압(Vdata)은 당연히 열화 전과 열화 후의 측정에서 동일한 값으로 해야 한다.In this case, the test voltage Vdata should naturally be the same value in the measurement before and after deterioration.
이어서, 상기 열화 전의 측정값, 즉 목표전류 값과 열화 후의 측정값으로부터 두 값을 비교하여 열화 전후의 전류 값의 변화를 비교함으로써 전류 값의 변화를 계산한다(단계 S17).Next, the change in the current value is calculated by comparing the two values from the measured value before deterioration, that is, the target current value and the measured value after deterioration, and comparing the change in the current value before and after deterioration (step S17).
이 계산은 공지의 방법에 의할 수 있고, 계산된 전류 값의 변화를 공지의 방법에 의해 표시부(100)의 복수의 화소 회로 각각을 원하는 휘도로 유지하기 위해 필요한 구동 트랜지스터(112)의 게이트 전극에서의 오프셋 전압의 값으로 변환하여, 예를 들어 룩업테이블 형태로 메모리(144)에 저장하면 좋다. 그러나 이에 한정되는 것은 아니며, 룩업테이블 대신 오프셋 전압 계산용 알고리즘을 메모리(144)에 저장하여, 필요시에 이 알고리즘에 의해 오프셋 전압을 계산하는 것으로 할 수도 있다.This calculation may be by a known method, and the gate electrode of the driving transistor 112 required to maintain each of the plurality of pixel circuits of the display unit 100 at a desired luminance by the known method by using a known method. The value may be converted into a value of an offset voltage at and stored in the memory 144 in the form of a lookup table, for example. However, the present invention is not limited thereto, and the offset voltage calculation algorithm may be stored in the memory 144 instead of the lookup table, and the offset voltage may be calculated by this algorithm when necessary.
그리고 상기 산출된 오프셋 전압은 각 화소 회로(P(i,j))의 구동 트랜지스터(112)의 문턱 전압의 변화와 유기EL소자(114)의 열화에 따른 전류 값의 변화에 따른 휘도 편차를 일괄해서 한 번에 보상하기 위한 자료로서 제공된다.In addition, the calculated offset voltage collectively includes a luminance deviation due to a change in the threshold voltage of the driving transistor 112 of each pixel circuit P (i, j) and a change in the current value due to deterioration of the organic EL element 114. It is provided as a data to compensate at a time.
구체적으로는, 상기 오프셋 전압은 예를 들어 컨트롤러(120)에 제공되며, 컨트롤러(120)는 입력단자를 통해 입력되는 화상 신호(Data)를 복수의 화소 회로별로 각각 산출된 오프셋 전압에 의해 보정하여 각 화소 회로에 제공함으로써 유기발광 표시장치의 장시간 사용에 따른 열화 시에도 휘도의 저하 및 휘도 불 균일이 없는 표시장치를 제공할 수 있다.Specifically, the offset voltage is provided to, for example, the controller 120, and the controller 120 corrects the image signal Data input through the input terminal by the offset voltages calculated for each of the plurality of pixel circuits. By providing each pixel circuit, it is possible to provide a display device which is free from luminance deterioration and luminance unevenness even when deteriorated due to long-term use of the organic light emitting display device.
2. 실시형태 22. Embodiment 2
다음에, 본 발명의 바람직한 실시형태 2에 대해 설명한다. 도 2는 본 발명의 바람직한 실시형태 2의 유기발광 표시장치의 구성을 개략적으로 나타내는 회로도이다.Next, Preferred Embodiment 2 of the present invention will be described. 2 is a circuit diagram schematically showing the configuration of an organic light emitting display device according to a second preferred embodiment of the present invention.
본 실시형태 2의 유기발광 표시장치는 도 5에 도시하는 것과 같이 표시부(200), 선택스위치(215), 전류 싱크(260), 전류측정회로(240), 변동치 보정부(220) 및 데이터 드라이버(250)를 포함하며, 도 2에는 도시하고 있지 않으나, 각 게이트 라인(Lgi)에 선택신호를 인가하는 게이트 드라이버, 제 1 전압 원(VDD)으로부터 각 애노드 라인(Lai)에 구동전압을 인가하는 애노드 드라이버, 표시장치의 각 부를 제어하는 컨트롤러 등의 공지의 구성도 포함한다.In the organic light emitting display device of the second embodiment, as shown in FIG. 5, the display unit 200, the selection switch 215, the current sink 260, the current measurement circuit 240, the variation value correction unit 220, and the data driver are shown. Although not shown in FIG. 2, a gate driver applying a selection signal to each gate line Lgi and a driving voltage applied to each anode line Lai from the first voltage source VDD are included. It also includes well-known configurations, such as an anode driver and the controller which controls each part of a display apparatus.
표시부(200)는 각각 평행하게 배치된 복수의 게이트 라인(Lg1~Lgn)(n은 2 이상의 정수)과 복수의 데이터 라인(Ld1~m)(m은 2 이상의 정수) 및 복수의 애노드 라인(La1~n)를 구비하고 있고, 복수의 게이트 라인(Lg1~n)과 복수의 애노드 라인(La1~n)은 서로 평행하게 배열되어 있다. 또, 복수의 데이터 라인(Ld1~m)은 복수의 게이트 라인(Lg1~n) 및 복수의 애노드 라인(La1~n)과 서로 교차하고 있다.The display unit 200 includes a plurality of gate lines Lg1 to Lgn (n is an integer of 2 or more), a plurality of data lines Ld1 to m (m is an integer of 2 or more), and a plurality of anode lines La1, which are respectively disposed in parallel. n, and the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n are arranged in parallel with each other. The plurality of data lines Ld1 to m intersect with the plurality of gate lines Lg1 to n and the plurality of anode lines La1 to n.
각각의 게이트 라인(Lg1~n)과 각각의 데이터 라인(Ld1~m)이 교차하는 각 교차영역에는 각각 화소 회로(Px(i,j))(i=1~n, j=1~m, m, n은 각각 자연수)가 배치되며, 복수의 화소 회로(P(i,j))는 n행 m열(m, n은 각각 자연수)의 매트릭스 형상으로 배열되어서 표시부(200)를 형성한다.Pixel circuits Px (i, j) (i = 1 to n, j = 1 to m, respectively) are provided in each intersection area where each gate line Lg1 to n and each data line Ld1 to m cross each other. m and n are natural numbers, respectively, and the plurality of pixel circuits P (i, j) are arranged in a matrix form of n rows and m columns (m and n are natural numbers, respectively) to form the display unit 200.
또, 복수의 화소 회로(P(i,j)) 각각은 판독 라인(Lri)을 가지며, 판독 라인(Lri)을 포함한 각 화소 회로(P(i,j))의 세부 구성에 대해서는 후술한다.Each of the plurality of pixel circuits P (i, j) has a read line Lri, and the detailed configuration of each pixel circuit P (i, j) including the read line Lri will be described later.
표시부(200)의 복수의 화소 회로(P(i,j))는 각각 게이트 라인(Lg1~n)을 통해서 게이트 드라이버(230)에 접속되고, 또, 데이터 라인(Ld1~m)을 통해서 데이터 드라이버(250)와 접속되며, 애노드 라인(La1~n)을 통해서 애노드 드라이버(270)와 접속된다.The plurality of pixel circuits P (i, j) of the display unit 200 are connected to the gate driver 230 through the gate lines Lg1 to n, respectively, and the data driver through the data lines Ld1 to m. It is connected to the 250 and is connected to the anode driver 270 through the anode lines La1 to n.
데이터 드라이버(250)는 복수의 데이터 라인(Ldj)을 통해서 복수의 화소 회로(P(i,j)) 각각에 화상 신호(Data)를 인가하는 기능을 담당하는 이외에, 본 발명에서는 휘도 편차 보상을 위해서 각 화소 회로(P(i,j))별로 구동트랜지스터(212)의 문턱 전압 변동치 및 각 유기EL소자(214)의 구동전압 변동치를 측정하는 과정에서 각각 구동트랜지스터(212) 및 판독트랜지스터(216)에 시험전압(Vdata)을 인가하는 기능도 담당한다. 상세에 대해서는 후술한다.The data driver 250 is responsible for applying the image signal Data to each of the plurality of pixel circuits P (i, j) through the plurality of data lines Ldj. In order to measure the threshold voltage variation of the driving transistor 212 and the driving voltage variation of each organic EL element 214 for each pixel circuit P (i, j), the driving transistor 212 and the reading transistor 216 are respectively measured. It is also in charge of applying the test voltage (Vdata) to. Details will be described later.
선택스위치(215)는 후술하는 화소 회로(P(i,j))의 유기EL소자(214)의 캐소드 측을 전류 싱크(260)와 제 2 전압 원(Vss) 사이에서 선택적으로 접속하며, 후술하는 휘도 편차 보상을 위한 각 화소 회로(P(i,j))별 구동트랜지스터(212)의 문턱 전압 변동치 및 각 유기EL소자(214)의 구동전압 변동치 측정시에는 각 유기EL소자(214)의 캐소드를 전류 싱크(260) 측과 연결하고, 통상의 표시장치로서 동작시에는 각 유기EL소자(214)의 캐소드를 제 2 전압 원(Vss)과 연결하며, 이 동작은 미 도시의 컨트롤러의 제어 하에 이루어질 수 있다.The selection switch 215 selectively connects the cathode side of the organic EL element 214 of the pixel circuit P (i, j), which will be described later, between the current sink 260 and the second voltage source Vss. When the threshold voltage fluctuations of the driving transistors 212 for each pixel circuit P (i, j) are measured and the driving voltage fluctuations of the organic EL elements 214 are measured, the luminance of each organic EL element 214 is measured. The cathode is connected to the current sink 260 side, and when operating as a normal display device, the cathode of each organic EL element 214 is connected to the second voltage source Vss, and this operation is controlled by a controller of an illustrated figure. Can be made under.
전류 싱크(260)는 일단이 선택스위치(215)와 접속되고 타단은 전류측정회로(240)를 통해서 변동치 보정부(220)와 접속되며, 선택스위치(215)에 의해 화소 회로(P(i,j))의 유기EL소자(214)의 캐소드와 접속된 때에 미리 정해진 데이터 값이 데이터 라인(Ldj)에 인가되면 표시부(200)의 각 화소 회로(P(i,j))에 일정 값의 전류를 흘린다.One end of the current sink 260 is connected to the selection switch 215, and the other end thereof is connected to the variation correction unit 220 through the current measurement circuit 240, and the pixel circuit P (i, j) a predetermined value of current is applied to each pixel circuit P (i, j) of the display unit 200 when a predetermined data value is applied to the data line Ldj when the cathode of the organic EL element 214 is connected. Shed.
게이트 드라이버를 비롯한 공지의 구성요소들은 본 발명의 주제와는 직접적인 관련은 없으므로, 본 발명의 이해를 위해 꼭 필요한 부분에 대해서만 필요한 범위 내에서 후술하고, 그 외의 상세한 설명은 생략한다.Since well-known components including the gate driver are not directly related to the subject matter of the present invention, only the parts necessary for understanding the present invention will be described later within the necessary range, and other detailed descriptions will be omitted.
또, 전류측정회로(240)는 전류 측정부(242), A/D 컨버터(243), 변동치 계산부(241) 및 메모리(244)를 포함하며, 상세에 대해서는 후술한다.The current measuring circuit 240 includes a current measuring unit 242, an A / D converter 243, a variation calculating unit 241, and a memory 244, which will be described later in detail.
다음에, 화소 회로(P(i,j))의 상세한 구성 및 휘도 편차 보상장치에 대해서 설명한다. 도 6은 본 발명의 바람직한 실시형태 2의 화소 회로 및 휘도 편차 보상장치의 주요 구성을 나타내는 회로도이다.Next, the detailed configuration of the pixel circuit P (i, j) and the luminance deviation compensator will be described. Fig. 6 is a circuit diagram showing a main configuration of a pixel circuit and a luminance deviation compensating device of preferred embodiment 2 of the present invention.
본 실시형태 2의 화소 회로(P(i,j)) 각각은 도 6에 도시하는 것과 같이 유기EL소자(214)와 구동트랜지스터(212)와 스위칭 트랜지스터(211)와 판독트랜지스터(216) 및 커패시터(213)를 포함하며, 각 트랜지스터(211, 212, 216)는 제 1 전극과 제 2 전극 및 게이트 전극을 갖는다.Each of the pixel circuits P (i, j) of the second embodiment has an organic EL element 214, a driving transistor 212, a switching transistor 211, a read transistor 216 and a capacitor as shown in FIG. 213, each transistor 211, 212, 216 has a first electrode, a second electrode, and a gate electrode.
스위칭 트랜지스터(211)의 게이트 전극은 게이트 라인(Lgi)을 통해서 게이트 드라이버(미 도시)와 접속되고, 제 1 전극은 데이터 라인(Ldj)과 접속되며, 제 2 전극은 구동트랜지스터(212)의 게이트 단과 접속되어서, 게이트 드라이버로부터 공급되는 주사 신호(행 선택신호)에 의해 온(on) 하여 각각 데이터 라인(Ldj)에 입력되는 화상 신호(Data)(또는 시험전압(Vdata))를 구동트랜지스터(212)의 게이트 전극 및 커패시터(213)의 일단에 출력한다.The gate electrode of the switching transistor 211 is connected to a gate driver (not shown) through the gate line Lgi, the first electrode is connected to the data line Ldj, and the second electrode is a gate of the driving transistor 212. Connected to the stage and turned on by the scan signal (row selection signal) supplied from the gate driver to drive the image signal Data (or test voltage Vdata) input to the data line Ldj, respectively, the driving transistor 212 Is output to one end of the gate electrode and the capacitor 213.
각 화소 회로(P(i,j))의 구동트랜지스터(212)의 제 1 전극은 제 1 전압 원(VDD) 및 커패시터(213)의 타단과 접속되며, 여기서 제 1 전압 원(VDD)은 별도의 애노드 드라이버(미 도시)를 갖는 표시장치에서는 애노드 드라이버를 통해서 공급되는 전압 원일 수 있고, 복수의 화소 회로(P(i,j))의 애노드 라인(La1~n)에 대해 동시에 애노드 전압을 인가하는 이른바 공통 애노드인 경우에는 공통 애노드용 전압 원일 수 있다.The first electrode of the driving transistor 212 of each pixel circuit P (i, j) is connected to the first voltage source VDD and the other end of the capacitor 213, where the first voltage source VDD is separately In a display device having an anode driver (not shown), the display device may be a voltage source supplied through the anode driver, and the anode voltage is simultaneously applied to the anode lines La1 to n of the plurality of pixel circuits P (i, j). In the case of the so-called common anode, the voltage source may be a common anode.
또, 구동트랜지스터(212)의 제 2 전극은 유기EL소자(214)의 애노드와 접속되고, 유기EL소자(214)의 캐소드는 선택스위치(215)를 통해서 제 2 전압 원(Vss) 또는 전류 싱크(260) 중 어느 하나와 선택적으로 접속된다. 또, 구동트랜지스터(212)의 게이트 전극은 스위칭 트랜지스터(211)에 접속되며, 데이터 라인(Ldj)을 통해 공급되는 화상 신호(Data)(또는 시험전압(Vdata))를 선택적으로 구동트랜지스터(212)에 제공한다.The second electrode of the driving transistor 212 is connected to the anode of the organic EL element 214, and the cathode of the organic EL element 214 is connected to the second voltage source Vss or current sink through the selection switch 215. It is selectively connected to any one of 260. In addition, the gate electrode of the driving transistor 212 is connected to the switching transistor 211, and selectively drives the image signal Data (or test voltage Vdata) supplied through the data line Ldj. To provide.
판독트랜지스터(216)의 게이트 전극은 판독 라인(Lri)을 통해서 미 도시의 판독 드라이버와 접속되며, 제 1 전극은 데이터 라인(Ldj) 및 스위칭 트랜지스터(211)의 제 1 전극과 접속되고, 제 2 전극은 구동트랜지스터(212)의 제 2 전극 및 유기EL소자(214)의 애노드 단과 접속되며, 미 도시의 판독 드라이버로부터 공급되는 선택신호에 의해 온(on) 하여 데이터 라인(Ldj)에 입력된 시험전압(Vdata)를 유기EL소자(214)의 애노드 단에 공급한다.The gate electrode of the read transistor 216 is connected to a read driver (not shown) through the read line Lri, and the first electrode is connected to the first electrode of the data line Ldj and the switching transistor 211, and the second electrode. The electrode is connected to the second electrode of the driving transistor 212 and the anode end of the organic EL element 214, and is turned on by a selection signal supplied from a read driver (not shown) to be input to the data line Ldj. The voltage Vdata is supplied to the anode terminal of the organic EL element 214.
여기서, 판독트랜지스터(216)를 선택적으로 구동하는 판독 드라이버는 공지의 유기발광 표시장치의 게이트 드라이버가 그 기능을 겸해도 좋고, 게이트 드라이버와는 별개로 판독 드라이버를 더 구비해도 좋다. 게이트 드라이버가 판독 드라이버의 기능을 겸하는 경우에는 공지의 게이트 드라이버에 스위칭 트랜지스터(211)와 판독트랜지스터(216) 중 어느 하나를 택일적으로 선택하는 스위칭기능을 부가하면 된다.The read driver for selectively driving the read transistor 216 may have a function of a gate driver of a known organic light emitting display device, or may further include a read driver separately from the gate driver. If the gate driver also functions as a read driver, a switching function for selectively selecting either the switching transistor 211 or the read transistor 216 may be added to the known gate driver.
도 5에 도시하는 것과 같이 본 실시형태 2의 표시장치에서는 n행 m열의 복수의 화소 회로(P(i,j))의 캐소드가 서로 연결된 이른바 공통 캐소드(common cathod)이며, 공통 캐소드는 1개의 선택스위치(215)를 통해서 1개의 제 2 전압 원(Vss)과 접속된다.As shown in Fig. 5, in the display device of the second embodiment, the cathodes of the plurality of pixel circuits P (i, j) in n rows and m columns are connected to each other, and the common cathode is one common cathode. It is connected to one second voltage source Vss through the selection switch 215.
전류측정회로(240)는 선택스위치(215) 및 전류 싱크(260)를 통해서 각 화소 회로(P(i,j))에 흐르는 전류를 측정하는 전류 측정부(242)와, 전류 측정부(242)가 측정한 아날로그 신호를 디지털 신호로 변환하는 A/D 컨버터(243)와, 후술하는 표시장치의 열화 전과 열화 후의 각 화소 회로(P(i,j))의 특성 값을 비교하여 변동치를 계산하는 변동 값 연산부(241) 및 이들 값을 기억하는 메모리(244)를 포함한다.The current measuring circuit 240 includes a current measuring unit 242 and a current measuring unit 242 for measuring a current flowing through each pixel circuit P (i, j) through the selection switch 215 and the current sink 260. The A / D converter 243 converts the analog signal measured by the digital signal into a digital signal, and compares the characteristic values of each pixel circuit P (i, j) before and after deterioration of the display device to be described later. A variation value calculating section 241 and a memory 244 storing these values.
이와 같은 구성에 의해 전류측정회로(240)는 전류 싱크(260) 및 선택스위치(215)를 통해서 표시부(200)의 복수의 화소 회로(P(i,j))의 공통 캐소드와 선택적으로 연결되며, 복수의 화소 회로(P(i,j)) 각각에 흐르는 전류를 순차 판독하여, 이로부터 후술하는 구동트랜지스터(212)의 문턱 전압 변동치 및 유기EL소자(214)의 구동전압 변동치를 계산한다.In this configuration, the current measurement circuit 240 is selectively connected to the common cathode of the plurality of pixel circuits P (i, j) of the display unit 200 through the current sink 260 and the selection switch 215. The current flowing through each of the plurality of pixel circuits P (i, j) is sequentially read, and the threshold voltage fluctuation value of the driving transistor 212 and the driving voltage fluctuation value of the organic EL element 214 which are described later are calculated therefrom.
변동치 보정부(220)는 후술하는 방법에 의해 변동 값 연산부(241)가 계산한 구동트랜지스터(212)의 문턱 전압 변동치 및 유기EL소자(214)의 구동전압 변동치를 입력단을 통해서 입력되는 화상 신호(Data)에 가산하여 D/A 컨버터(245) 및 데이터 라인(Ldj)을 통해서 표시부(200)의 각 화소 회로(P(i,j))에 공급한다.The variation value correction unit 220 is an image signal inputted through an input terminal of the threshold voltage variation value of the driving transistor 212 and the driving voltage variation value of the organic EL element 214 calculated by the variation value calculation unit 241 by the method described below. Data is added to each pixel circuit P (i, j) of the display unit 200 through the D / A converter 245 and the data line Ldj.
D/A 컨버터(245)는 변동치 보정부(220)로부터 표시부(200)의 각 화소 회로(P(i,j))에 공급되는 디지털 데이터를 아날로그 데이터로 변환한다.The D / A converter 245 converts the digital data supplied from the variation correction unit 220 to the pixel circuits P (i, j) of the display unit 200 into analog data.
도 5, 6에는 구체적으로 도시하고 있지 않으나, 변동치 보정부(220)는 공지의 유기발광 표시장치의 동작을 전체적으로 제어하는 컨트롤러가 그 기능을 겸하는 것으로 해도 좋고, 컨트롤러와는 별개의 독립된 구성으로 해도 좋다.Although not specifically illustrated in FIGS. 5 and 6, the variation correction unit 220 may have a controller that controls the operation of a known organic light emitting display device as a whole, and may have a function independent of the controller. good.
다음에, 본 실시형태 2의 동작 설명에 앞서 본 실시형태의 휘도 편차 보상의 개념에 대해서 설명한다.Next, the concept of the luminance deviation compensation of the present embodiment will be described before explaining the operation of the second embodiment.
앞에서도 설명한 것과 같이, 유기발광 표시장치의 사용에 따른 휘도 저하의 원인으로는 각 화소 회로를 구성하는 구동트랜지스터의 열화에 따른 문턱 전압의 변동과 유기EL소자의 내부 저항의 변화에 따른 구동전압의 변동을 들 수 있다.As described above, the cause of the decrease in luminance due to the use of the organic light emitting display device is the variation of the threshold voltage due to the deterioration of the driving transistors constituting each pixel circuit and the driving voltage due to the change in the internal resistance of the organic EL element. Fluctuations.
유기발광 표시장치의 휘도는 유기발광 표시장치의 각 화소 회로에 흐르는 전류량과 관계를 가지며, 구동트랜지스터의 문턱 전압의 변동과 유기EL소자의 내부 저항의 변화에 따른 구동전압의 변화를 보상하여, 유기발광 표시장치의 각 화소 회로에 흐르는 전류량을 적정 휘도의 유지에 적합한 값으로 조절하면 장시간 사용에 따른 휘도 저하를 보상할 수 있다는 것이 본 발명의 기본 생각이다.The luminance of the organic light emitting diode display is related to the amount of current flowing through each pixel circuit of the organic light emitting diode display and compensates for the change in the driving voltage due to the variation of the threshold voltage of the driving transistor and the internal resistance of the organic EL element. The basic idea of the present invention is to adjust the amount of current flowing through each pixel circuit of the light emitting display device to a value suitable for maintaining an appropriate luminance, thereby compensating for a decrease in luminance due to prolonged use.
또, 유기발광 표시장치에서는 복수의 화소 회로 각각의 발광빈도 또는 각 화소 회로의 유기발광 층 재료의 차이 등의 다양한 변수에 따라서 복수의 화소 회로 각각의 휘도 저하의 정도에 편차가 발생하므로, 휘도 편차의 보상은 복수의 화소 회로 각각에 대해 개별적으로 이루어져야 한다.Further, in the organic light emitting display device, a deviation occurs in the degree of deterioration of the luminance of each of the plurality of pixel circuits according to various variables such as the emission frequency of each of the plurality of pixel circuits or the difference of the organic light emitting layer material of each pixel circuit. Compensation must be made separately for each of the plurality of pixel circuits.
또, 유기발광 표시장치의 각 화소 회로에 흐르는 전류량의 조절을 위해서는 표시장치의 사용에 따른 열화 전에, 예를 들어 유기발광 표시장치를 표시장치로서 사용하기 전에 각 화소 회로에 소정의 값의 시험전압을 인가한 때의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하고, 일정 시간 사용에 의해 표시장치가 열화한 후에 열화 전과 동일한 조건 하에서 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 각각 측정하여, 그 측정결과로부터 구동 트랜지스터의 문턱 전압 변동치 및 유기EL소자의 구동전압 변동치를 보상한다.In addition, in order to adjust the amount of current flowing through each pixel circuit of the organic light emitting display device, a test voltage having a predetermined value is applied to each pixel circuit before deterioration due to the use of the display device, for example, before the organic light emitting display device is used as the display device. Measure the voltage between the gate source of the driving transistor and the driving voltage of the organic EL element when the voltage is applied, and the voltage between the gate and source of the driving transistor of each pixel circuit under the same conditions as before deterioration after the display device deteriorates by use for a predetermined time. And the driving voltage of the organic EL element are respectively measured, and the threshold voltage variation of the driving transistor and the driving voltage variation of the organic EL element are compensated for from the measurement result.
다음에, 본 발명의 동작에 대해서 설명한다. 도 7은 본 발명의 바람직한 실시형태 2의 휘도 편차 보상방법의 흐름을 나타내는 플로차트이다.Next, the operation of the present invention will be described. Fig. 7 is a flowchart showing the flow of the luminance deviation compensation method of the second preferred embodiment of the present invention.
도 7에 도시하는 것과 같이, 먼저, 유기발광 표시장치의 열화 전의 표시부(200)의 복수의 화소 회로 각각의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS21) 및 유기EL소자(214)의 구동전압(VOLED1)을 측정하고, 그 측정결과를 복수의 화소 회로 각각에 대응시켜서 메모리(244)에 기억한다(단계 S21).As shown in FIG. 7, first, the gate-source voltage V GS21 and the organic EL element 214 of the driving transistor 212 of each of the plurality of pixel circuits of the display unit 200 before deterioration of the organic light emitting display device. The driving voltage V OLED1 is measured and stored in the memory 244 in association with each of the plurality of pixel circuits (step S21).
여기서, 유기발광 표시장치의 열화 전의 측정은 유기발광 표시장치를 표시장치로서 사용하기 전의 초기상태에서 측정해도 좋고, 일정 시간 사용에 의해 당해 유기발광 표시장치의 동작이 안정화된 시점에서 측정해도 좋으며, 그 외의 다른 시기에 측정해도 상관없다.Here, the measurement before deterioration of the organic light emitting display device may be measured in an initial state before using the organic light emitting display device as a display device, or may be measured when the operation of the organic light emitting display device is stabilized by use of a predetermined time. You may measure at other times.
이하, 단계 S21의 표시장치의 열화 전의 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하는 방법에 대해서 상세하게 설명한다. 도 8은 본 발명의 바람직한 실시형태 2의 표시장치 열화 전의 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하는 방법의 흐름을 나타내는 플로차트이다.Hereinafter, a method of measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element before deterioration of the display device of step S21 will be described in detail. Fig. 8 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element before the display device deterioration of the preferred embodiment 2 of the present invention.
먼저, 선택스위치(215)를 전류 싱크(260) 측으로 전환한 후(단계 S31), 측정을 하려고 하는 선택된 화소 회로(P(i,j))의 스위칭 트랜지스터(211) 및 구동트랜지스터(212)를 온(On) 하고 판독트랜지스터(216)를 오프(Off) 한다(단계 S32).First, the select switch 215 is switched to the current sink 260 side (step S31), and then the switching transistor 211 and the driving transistor 212 of the selected pixel circuit P (i, j) to be measured are turned off. On and the read transistor 216 are turned off (step S32).
이어서, 선택된 화소 회로(P(i,j))에 소정 값의 시험전압(Vdata)을 인가한다(단계 S33). 본 실시형태 2에서는 시험전압(Vdata)으로 5V를 인가하는 것으로 가정하여 설명한다.Subsequently, a test voltage Vdata having a predetermined value is applied to the selected pixel circuit P (i, j) (step S33). In the second embodiment, it is assumed that 5 V is applied as the test voltage Vdata.
여기서, 게이트 드라이버가 선택된 화소 회로(P(i,j))의 게이트 단자에 행 선택신호를 인가함으로써 스위칭 트랜지스터(211)가 온이 되고, 스위칭 트랜지스터(211)가 온이 됨에 따라서 구동트랜지스터(212)도 온이 되어서 데이터 라인(Ldj)을 통해서 소정 값의 시험전압(Vdata)(본 실시형태 2에서는 5V)이 구동트랜지스터(212)의 게이트 전극 및 커패시터(213)의 일단에 인가되게 된다.Here, the switching transistor 211 is turned on by applying the row selection signal to the gate terminal of the pixel circuit P (i, j) where the gate driver is selected, and thus the driving transistor 212 is turned on as the switching transistor 211 is turned on. ) Is also turned on so that a test voltage Vdata (5V in the second embodiment) of a predetermined value is applied to one end of the gate electrode and the capacitor 213 of the driving transistor 212 through the data line Ldj.
이어서, 제 1 전압 원(VDD)으로부터 애노드 전압을 인가하면 상기 시험전압(Vdata)에 대응하는 값의 전류(IOLED1)가 제 1 전압 원(VDD)으로부터 구동트랜지스터(212), 유기EL소자(214) 및 선택스위치(215)를 통해서 전류 싱크(260)로 흐르며, 전류 측정부(242)에서 이 전류, 즉 선택된 화소 회로(P(i,j))를 흐르는 전류(IOLED1)를 측정하고, 측정한 전류 값은 A/D 컨버터(243)에서 디지털 값으로 변환되어 메모리(244)에 기억된다(단계 S34).Subsequently, when the anode voltage is applied from the first voltage source VDD, the current I OLED1 having a value corresponding to the test voltage Vdata is driven from the first voltage source VDD by the driving transistor 212 and the organic EL element ( 214 and the selector switch 215 to the current sink 260, the current measuring unit 242 measures this current, that is, the current (I OLED1 ) flowing through the selected pixel circuit (P (i, j)) and The measured current value is converted into a digital value by the A / D converter 243 and stored in the memory 244 (step S34).
본 실시형태 2에서는 구동트랜지스터(212)의 게이트 전극 및 커패시터(213)의 일단에 상기 소정 값의 시험전압(Vdata)으로 5V의 전압을 인가한 때에 당해 화소 회로(P(i,j))의 유기EL소자(214)에 흐르는 전류(IOLED1), 즉, 전류 측정부(242)가 측정한 전류(IOLED1)는 1㎂인 것으로 가정하며, 이하의 설명에서는 이 전류 값 1㎂를 「기준전류」라고 한다.In the second embodiment, when a voltage of 5V is applied to one end of the gate electrode and the capacitor 213 of the driving transistor 212 with the test voltage Vdata of the predetermined value, the pixel circuit P (i, j) It is assumed that the current I OLED1 flowing through the organic EL element 214, that is, the current I OLED1 measured by the current measuring unit 242 is 1 ㎂. Current ”.
여기서, 선택된 화소 회로(P(i,j))의 유기EL소자(214)에 흐르는 전류(IOLED1)가 1㎂라는 것은 설명의 편의를 위해 표시부(200)의 n행 m열의 복수의 화소 회로 중에서 특정한 하나의 화소 회로(P(i,j))의 전류 값을 예로 들어서 설명하는 것이며, n행 m열의 복수의 화소 회로 중에서 상기 특정 화소 회로 P(i,j) 이외의 다른 화소 회로로부터 측정된 전류 값은 상기 특정 화소 회로(P(i,j))의 전류 값과 동일할 수도 있고, 다른 값일 수도 있으며, 이는 이하에서 설명하는 구동트랜지스터(212)의 게이트 전압(VG), 소스 전압(VS), 게이트 소스 간 전압(VGS) 및 유기EL소자(214)의 구동전압(VOLED)에서도 동일하다.Here, the fact that the current I OLED1 flowing in the organic EL element 214 of the selected pixel circuit P (i, j) is 1 ㎂ for the convenience of explanation, the plurality of pixel circuits in the n-row m-column of the display unit 200 The current value of one specific pixel circuit P (i, j) is described as an example, and is measured from pixel circuits other than the specific pixel circuit P (i, j) among a plurality of pixel circuits in n rows and m columns. The current value may be the same as the current value of the specific pixel circuit P (i, j), or may be a different value, which is a gate voltage V G and a source voltage of the driving transistor 212 described below. The same applies to V S , the gate-to-gate voltage V GS , and the driving voltage V OLED of the organic EL element 214.
여기서, 구동트랜지스터(212)의 게이트 전극 및 커패시터(213)의 일단에 인가되는 상기 소정 값의 시험전압(Vdata)(본 실시형태 2에서는 5V)은 제 1 전압 원(VDD)으로부터 인가되는 애노드 전압과는 다른 전압이다.Here, the test voltage Vdata (5V in the second embodiment) of the predetermined value applied to the gate electrode of the driving transistor 212 and one end of the capacitor 213 is the anode voltage applied from the first voltage source VDD. Is a different voltage than.
이어서, 스위칭 트랜지스터(211) 및 구동트랜지스터(212)를 오프 하고 판독트랜지스터(216)를 온으로 하여(단계 S35) 유기EL소자(214)에 시험전압(Vdata)을 인가한다(단계 S36).Next, the switching transistor 211 and the driving transistor 212 are turned off and the read transistor 216 is turned on (step S35) to apply the test voltage Vdata to the organic EL element 214 (step S36).
이때 유기EL소자(214)에 인가하는 시험전압(Vdata)은 단계 S34에서 측정한 선택된 화소 회로(P(i,j))에 흐른 전류(IOLED1)와 동일한 값의 전류(본 실시형태 2에서는 1㎂)가 당해 화소 회로(P(i,j))에 흐르도록 하기 위한 전압이며, 단계 S36에서는 이 전압 값을 측정한다. 본 실시형태 2에서는 단계 S36에서 측정된 전압은 2V인 것으로 가정한다.At this time, the test voltage Vdata applied to the organic EL element 214 is equal to the current I OLED1 flowing in the selected pixel circuit P (i, j) measured in step S34 (in the second embodiment) 1 kV is a voltage for flowing into the pixel circuit P (i, j), and the voltage value is measured in step S36. In Embodiment 2, it is assumed that the voltage measured in step S36 is 2V.
이어서, 단계 S37로 진행하여, 이상의 결과로부터 선택된 화소 회로(P(i,j))의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS21) 및 당해 화소 회로(P(i,j))의 유기EL소자(214)의 구동전압(VOLED1)을 계산한다. 본 실시형태 2에서는 화소 회로(P(i,j))의 동작전류(IOLED1)가 1㎂일 때의 구동트랜지스터(212)의 게이트 전압(VG)은 5V, 소스 전압(VS)은 2V이므로 게이트 소스 간 전압(VGS21)은 3V가 되고, 유기EL소자(214)의 구동전압(VOLED1)은 2V가 되며, 이들 값은 해당 화소 회로와 대응시켜서 메모리(244)에 기억시킨다.Subsequently, the process proceeds to step S37, in which the voltage V GS21 between the gate and source of the driving transistor 212 of the pixel circuit P (i, j) selected from the above result and the pixel circuit P (i, j) of the pixel circuit P (i, j) are selected. The driving voltage V OLED1 of the organic EL element 214 is calculated. In the second embodiment, the gate voltage V G of the driving transistor 212 when the operating current I OLED1 of the pixel circuit P (i, j) is 1 ㎂ is 5V, and the source voltage V S is Since it is 2V, the gate-source voltage V GS21 becomes 3V, the drive voltage V OLED1 of the organic EL element 214 becomes 2V, and these values are stored in the memory 244 in correspondence with the pixel circuit.
여기서, 예를 들어 표시부(200)가 n행 m열의 복수의 화소 회로를 갖는 경우, 각 화소 회로를 흐르는 전류의 측정은 복수의 화소 회로 각각에 대해 모두 이루어져야 하며, 따라서 단계 S38에서는 측정할 화소 회로가 남아 있는가 여부를 판단한다.Here, for example, when the display unit 200 has a plurality of pixel circuits in n rows and m columns, the measurement of the current flowing through each pixel circuit should be made for each of the plurality of pixel circuits, and therefore, the pixel circuit to be measured in step S38. Determine whether is left.
단계 S38에서 화소 회로를 흐르는 전류 값을 측정할 화소 회로가 더 남아 있는 것으로 판단되면(단계 S38=Yes) 단계 S32으로 복귀하여 다음 화소 회로에 대하여 단계 S32 내지 단계 S38을 반복하고, 단계 S38에서 화소 회로를 흐르는 전류 값을 측정할 화소 회로가 더 이상 남아 있지 않은 것으로 판단되면(단계 S38=No) 종료한다.If it is determined in step S38 that there are still more pixel circuits to measure the current value flowing through the pixel circuit (step S38 = Yes), the process returns to step S32 to repeat steps S32 to S38 for the next pixel circuit, and in step S38 If it is determined that there are no more pixel circuits to measure the current value flowing through the circuit (step S38 = No), the process ends.
n행 m 열의 복수의 화소 회로 각각에 대해 각 화소 회로의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS21) 및 유기EL소자(214)의 구동전압(VOLED1)을 측정하는 방법으로는 n행 m 열의 복수의 화소 회로의 행 단위로 순차 측정하는 방법, 열 단위로 순차 측정하는 방법이 있을 수 있다.For each of the plurality of pixel circuits in the n rows and m columns, the voltage between the gate sources V GS21 of the driving transistor 212 of each pixel circuit and the driving voltage V OLED1 of the organic EL element 214 are measured by n. There may be a method of sequentially measuring in units of rows of a plurality of pixel circuits in a row m column, and a method of sequentially measuring in units of columns.
행 단위로 순차 측정하는 경우에는, 도 5에서 예를 들어 화소 회로(P(2,1)), 화소 회로(P(2,2)), …, 화소 회로(P(2,m)) 순으로 제 1 행째의 화소 회로에 대해 측정하고, 이어서 제 2 행째의 화소 회로, 제 3 행째, …, 제 n 행째의 화소 회로에 대해 순차적으로 측정할 수 있다.In the case of sequentially measuring in units of rows, for example, the pixel circuits P (2, 1), the pixel circuits P (2, 2),. , The pixel circuits of the first row are measured in the order of the pixel circuits P (2, m), followed by the pixel circuits of the second row, the third row,. It is possible to sequentially measure the pixel circuits of the nth row.
다른 방법으로, 열 단위로 순차 전류 값을 측정하는 경우에는, 도 5에서 예를 들어 화소 회로(P(2,1)), 화소 회로(P(2,1)), …, 화소 회로(P(n,1)) 순으로 제 1 열째의 화소 회로에 대해 측정하고, 이어서 제 2 열째, 제 3 열째, …, 제 n 열째의 화소 회로에 대해 순차적으로 측정해도 좋다.Alternatively, in the case where the sequential current values are measured in units of columns, the pixel circuits P (2, 1), pixel circuits P (2, 1),. , The pixel circuits of the first column are measured in the order of the pixel circuits P (n, 1), and then the second, third, The pixel circuits of the nth column may be measured sequentially.
또, 상기 설명에서는 제 1행 제 1 열의 화소 회로(P(2,1))부터 시작하여 제 n 행 제 m 열의 화소 회로(P(n,m))에서 종료하는 것으로 설명하였으나, 이에 한정되는 것은 아니며, n행 m 열의 복수의 화소 회로 중 어느 화소 회로부터 시작해도 상관없다. 중요한 점은 n행 m 열의 복수의 화소 회로 모두에 대해서 각 화소 회로의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS21) 및 유기EL소자(214)의 구동전압(VOLED1)을 측정하여 이를 각각의 화소 회로별로 대응시켜서 기억하면 된다.In the above description, it has been described that the pixel circuit P (2,1) in the first row and the first column ends in the pixel circuit P (n, m) in the nth row and m columns, but the present invention is not limited thereto. It is not necessary to start from any pixel circuit among the plurality of pixel circuits in n rows m columns. Importantly, the gate-to-gate voltage V GS21 of the driving transistor 212 of each pixel circuit and the driving voltage V OLED1 of the organic EL element 214 are measured for all of the plurality of pixel circuits in n rows m columns. The pixel circuits may be stored in correspondence with each pixel circuit.
도 7로 되돌아가서, 유기발광 표시장치의 열화 후의 표시부(200)의 복수의 화소 회로 각각의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS22) 및 유기EL소자(214)의 구동전압(VOLED2)을 측정하고, 그 측정결과를 복수의 화소 회로 각각에 대응시켜서 메모리(244)에 기억한다(단계 S22).Returning to FIG. 7, the voltage V GS22 between the gate sources of the driving transistors 212 of each of the plurality of pixel circuits of the display unit 200 after deterioration of the organic light emitting display device, and the driving voltage V of the organic EL element 214. OLED2 ) is measured and stored in the memory 244 in association with each of the plurality of pixel circuits (step S22).
여기서, 유기발광 표시장치의 열화 후의 측정은 유기발광 표시장치를 표시장치로서 일정 시간 사용한 후에 이루어지며, 그 시기는 유기발광 표시장치의 장시간 사용에 의해 유기발광 표시장치의 특성이 열화하는 시기를 고려하여 적절하게 결정할 수 있다. 또, 측정횟수는 당해 유기발광 표시장치의 수명기간 중 1회만 해도 2회 이상 하는 것으로 해도 좋다. 다시 말해 유기발광 표시장치의 열화에 따른 휘도 편차의 보상은 당해 유기발광 표시장치의 수명주기 중 1회만 할 수도 있고, 2회 이상 해도 좋다. 열화 후의 측정시기 및 횟수는 필요에 따라서 적절하게 결정할 수 있다.In this case, the measurement after deterioration of the organic light emitting display device is performed after using the organic light emitting display device as a display device for a predetermined time. Can be determined accordingly. The number of times of measurement may be one or two or more times during the lifetime of the organic light emitting display device. In other words, compensation for the luminance deviation due to deterioration of the organic light emitting display device may be performed only once in the life cycle of the organic light emitting display device or may be performed two or more times. The timing and frequency of measurement after deterioration can be appropriately determined as necessary.
이하에서는 상기 단계 S22의 표시장치의 열화 후의 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하는 방법에 대해서 도 9를 이용하여 상세하게 설명한다. 도 9는 본 발명의 바람직한 실시형태 2의 표시장치 열화 후의 각 화소 회로의 구동트랜지스터의 게이트 소스 간 전압과 유기EL소자의 구동전압을 측정하는 방법의 흐름을 나타내는 플로차트이다.Hereinafter, a method of measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element after deterioration of the display device of step S22 will be described in detail with reference to FIG. 9. Fig. 9 is a flowchart showing the flow of a method for measuring the voltage between the gate source of the driving transistor of each pixel circuit and the driving voltage of the organic EL element after the display device deterioration of the preferred embodiment 2 of the present invention.
먼저, 선택스위치(215)를 전류 싱크(260) 측으로 전환하고(단계 S41), 이어서, 선택된 화소 회로(P(i,j))의 스위칭 트랜지스터(211) 및 구동트랜지스터(212)를 온으로, 판독트랜지스터(216)를 오프로 한다(단계 S42). 여기서, 단계 S41 및 단계 S42는 열화 전의 측정에서의 단계 S31 및 단계 S32와 동일한 방법으로 실행하면 된다.First, the selection switch 215 is switched to the current sink 260 side (step S41), and then the switching transistor 211 and the driving transistor 212 of the selected pixel circuit P (i, j) are turned on, The read transistor 216 is turned off (step S42). Here, step S41 and step S42 may be performed by the same method as step S31 and step S32 in the measurement before deterioration.
이어서, 단계 S43에서 열화 전의 측정 시의 단계 S34에서 측정된 기준전류(본 실시형태 2에서는 1㎂)와 동일한 값의 전류(IOLED2)를 선택된 화소 회로(P(i,j))에 흘리기 위한 시험전압(Vdata)을 구동트랜지스터(212)에 인가하고, 그 전압을 측정한다. 본 실시형태 2에서는 선택된 특정 화소 회로(P(i,j))의 시험전압(Vdata)이 5.2V인 것으로 가정하여 설명한다.Subsequently, in order to flow the current I OLED2 having the same value as the reference current measured in step S34 at the time of measurement before deterioration in step S43 (1 mA in the second embodiment) to the selected pixel circuit P (i, j). The test voltage Vdata is applied to the driving transistor 212, and the voltage is measured. In the second embodiment, it is assumed that the test voltage Vdata of the selected specific pixel circuit P (i, j) is 5.2V.
이어서, 선택된 화소 회로(P(i,j))의 스위칭 트랜지스터(211) 및 구동트랜지스터(212)를 오프로 하고 판독트랜지스터(216)를 온으로 한 후(단계 S44), 단계 S45에서는 열화 전의 단계 S34에서 측정된 기준전류(본 실시형태 2에서는 1㎂)와 동일한 값의 전류(IOLED)를 선택된 화소 회로(P(i,j))에 흘리기 위한 시험전압(Vdata)을 판독트랜지스터(216)에 인가하고, 그 값을 측정한다. 본 실시형태 2에서는 측정된 시험전압(Vdata)은 2V인 것으로 가정한다.Next, after the switching transistor 211 and the driving transistor 212 of the selected pixel circuit P (i, j) are turned off and the read transistor 216 is turned on (step S44), in step S45, the step before deterioration is performed. The read transistor 216 reads the test voltage Vdata for flowing the current I OLED having the same value as the reference current measured in S34 (1 mA in the second embodiment) to the selected pixel circuit P (i, j). Is applied to and the value is measured. In the second embodiment, it is assumed that the measured test voltage Vdata is 2V.
이어서, 단계 S46으로 진행하여, 이상의 결과로부터 선택된 화소 회로(P(i,j))의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS22) 및 당해 화소 회로(P(i,j))의 유기EL소자(214)의 구동전압(VOLED2)을 계산한다. 본 실시형태 2에서는 화소 회로(P(i,j))의 동작전류(IOLED2)가 1㎂일 때의 구동트랜지스터(212)의 게이트 전압(VG)은 5.2V, 소스 전압(VS)은 2V이므로 게이트 소스 간 전압(VGS22)은 3.2V가 되고, 유기EL소자(214)의 구동전압(VOLED2)은 2V가 되며, 이들 값은 해당 화소 회로와 대응시켜서 메모리(244)에 기억시킨다.Subsequently, the process proceeds to step S46, in which the voltage V GS22 between the gate and source of the driving transistor 212 of the pixel circuit P (i, j) selected from the above result and the pixel circuit P (i, j) are changed . The driving voltage V OLED2 of the organic EL element 214 is calculated. In the second embodiment, the gate voltage V G of the driving transistor 212 when the operating current I OLED2 of the pixel circuit P (i, j) is 1 ㎂ is 5.2V and the source voltage V S. Is 2V, so the gate-to-gate voltage V GS22 is 3.2V, and the driving voltage V OLED2 of the organic EL element 214 is 2V, and these values are stored in the memory 244 in correspondence with the pixel circuit. Let's do it.
여기서, 예를 들어 표시부(200)가 n행 m열의 복수의 화소 회로를 갖는 경우, 화소 회로를 흐르는 전류의 측정은 복수의 화소 회로 각각에 대해 모두 이루어져야 하며, 따라서 단계 S47에서는 측정할 화소 회로가 남아 있는가 여부를 판단한다.Here, for example, when the display unit 200 has a plurality of pixel circuits in n rows and m columns, the measurement of the current flowing through the pixel circuits must be made for each of the plurality of pixel circuits, so that the pixel circuit to be measured is determined in step S47. Determine if it remains.
단계 S47에서 화소 회로를 흐르는 전류 값을 측정할 화소 회로가 더 남아 있는 것으로 판단되면(단계 S47=Yes) 단계 S42로 복귀하여 다음 화소 회로에 대해 단계 S42 내지 단계 S47을 반복하고, 단계 S47에서 화소 회로를 흐르는 전류 값을 측정할 화소 회로가 더 이상 남아 있지 않은 것으로 판단되면(단계 S47=No) 종료한다.If it is determined in step S47 that there are still more pixel circuits to measure the current value flowing through the pixel circuit (step S47 = Yes), the process returns to step S42 to repeat steps S42 to S47 for the next pixel circuit, and the pixel in step S47. If it is determined that the pixel circuit to measure the current value flowing through the circuit no longer remains (step S47 = No), the process ends.
열화 후의 복수의 화소 회로 각각의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS22) 및 유기EL소자(214)의 구동전압(VOLED2)을 순차 측정하는 방법은 앞에서 설명한 열화 전과 동일한 방법으로 하면 된다.When the same method method for sequentially measuring a drive voltage (V OLED2) of the gate-source voltage (V GS22) and an organic EL element 214 of each of the driving transistor 212 is a plurality of the pixel circuit after the deterioration is before degradation described previously do.
도 7로 되돌아가서, 단계 S21에서 측정한 복수의 화소 회로 각각의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS21) 및 유기EL소자(214)의 구동전압(VOLED1)과 단계 S22에서 측정한 복수의 화소 회로 각각의 구동트랜지스터(212)의 게이트 소스 간 전압(VGS22) 및 유기EL소자(214)의 구동전압(VOLED2)의 차이를 계산하여 각각의 화소 회로(P(i,j))의 문턱 전압 변동치(△Vth) 및 구동전압 변동치(△VOLED)를 계산하고, 계산된 문턱 전압 변동치(△Vth) 및 구동전압 변동치(△VOLED)를 합산한 값(△Vth+△VOLED)을 보상전압으로서 메모리(244)에 기억한다(단계 S23).Returning to FIG. 7, the voltage V GS21 between the gate sources of the driving transistors 212 of each of the plurality of pixel circuits measured in step S21 and the driving voltage V OLED1 of the organic EL element 214 are measured in step S22. The difference between the voltage V GS22 between the gate sources of the driving transistors 212 and the driving voltage V OLED2 of the organic EL device 214 of each of the plurality of pixel circuits is calculated and then the respective pixel circuits P (i, j The threshold voltage variation value ΔVth and the driving voltage variation value ΔV OLED are calculated, and the calculated threshold voltage variation value ΔVth and the driving voltage variation value ΔV OLED are added together (ΔVth + ΔV). OLED ) is stored in the memory 244 as a compensation voltage (step S23).
본 실시형태 2에서는 특정 화소 회로(P(i,j))에 대해 단계 S21에서 측정된 구동트랜지스터(212)의 게이트 소스 간 전압(VGS21)은 3V이고, 유기EL소자(214)의 구동전압(VOLED1)은 2V이며, 단계 S22에서 측정된 구동트랜지스터(212)의 게이트 소스 간 전압(VGS22)은 3.2V이고, 유기EL소자(214)의 구동전압(VOLED2)은 2V이므로 특정 화소 회로(P(i,j))의 문턱 전압 변동치(△Vth)는 +2V(3.2V - 3.0V = +2V)이고, 구동전압 변동치(△VOLED)는 0V(2V - 2V = 0V)가 되며, 문턱 전압 변동치(△Vth) 및 구동전압 변동치(△VOLED)를 합산한 화소 회로(P(i,j))의 보상전압은 +2V가 된다.In the second embodiment, the gate source-to-gate voltage V GS21 of the driving transistor 212 measured in step S21 for the specific pixel circuit P (i, j ) is 3V, and the driving voltage of the organic EL element 214. Since V OLED1 is 2V, the voltage V GS22 between the gate sources of the driving transistor 212 measured in step S22 is 3.2V, and the driving voltage V OLED2 of the organic EL element 214 is 2V, so that a specific pixel is obtained. The threshold voltage change value ΔVth of the circuit P (i, j) is + 2V (3.2V-3.0V = + 2V), and the drive voltage change value ΔV OLED is 0V (2V-2V = 0V). The compensation voltage of the pixel circuit P (i, j) obtained by adding the threshold voltage variation ΔVth and the driving voltage variation ΔV OLED is + 2V.
또, 특정 화소 회로(P(i,j)) 이외의 다른 화소 회로에 대해서도 동일한 방법으로 문턱 전압 변동치(△Vth) 및 구동전압 변동치(△VOLED)를 계산하고, 계산된 각 화소 회로의 문턱 전압 변동치(△Vth) 및 구동전압 변동치(△VOLED)를 합산한 값(△Vth+△VOLED)을 각각 당해 화소 회로의 보상전압으로 하여 해당 화소 회로별로 대응시켜서 메모리(244)에 기억한다.Also, for the pixel circuits other than the specific pixel circuit P (i, j), the threshold voltage fluctuation value? Vth and the driving voltage fluctuation value? V OLED are calculated in the same manner, and the calculated thresholds of the pixel circuits are calculated. The value ΔVth + ΔV OLED , which is the sum of the voltage fluctuation value ΔVth and the driving voltage fluctuation value ΔV OLED, is used as the compensation voltage of the pixel circuit, respectively, and is stored in the memory 244.
이어서, 단계 S24에서는 단계 S23에서는 선택스위치(215)를 제 2 전압 원(Vss) 측으로 전환하고, 상기 단계 S23에서 구한 보상전압을 메모리(244)로부터 변동치 보정부(220)에 제공하며, 변동치 보정부(220)는 입력단자를 통해 입력되는 각 화소 회로의 화상 신호(Data)에 가산(즉, Data+△Vth+△VOLED)하여 각각 대응하는 화소 회로에 제공하여 유기발광 표시장치를 구동함으로써 휘도 편차를 보상하며, 이에 의해 당해 유기발광 표시장치는 장시간 사용에 따른 열화에도 불구하고 휘도의 저하 및 휘도 불 균일이 없는 표시장치로서 사용될 수 있게 된다.Subsequently, in step S24, the selection switch 215 is switched to the second voltage source Vss side in step S23, and the compensation voltage obtained in step S23 is supplied from the memory 244 to the variation correction unit 220, and the variation value compensation is performed. The government unit 220 adds (i.e., Data + ΔVth + ΔV OLED ) to the image signal Data of each pixel circuit input through the input terminal and provides them to the corresponding pixel circuits to drive the organic light emitting display device, thereby causing luminance deviation. In this way, the organic light emitting display device can be used as a display device having no deterioration in luminance and luminance unevenness despite deterioration due to prolonged use.
<부호의 설명><Description of the code>
P(i,j) 화소 회로P (i, j) pixel circuit
111, 211 스위칭 트랜지스터111, 211 switching transistor
112, 212 구동 트랜지스터112, 212 driving transistor
113, 213 커패시터113,213 capacitors
114, 214 유기EL소자114, 214 Organic EL Devices
115, 215 선택스위치115, 215 selector switch
120 컨트롤러120 controller
130 게이트 드라이버130 gate driver
VDD 제 1 전압 원VDD first voltage source
Vss 제 2 전압 원Vss 2nd Voltage Source
140, 240 전류측정회로140, 240 current measurement circuit
142 A/D컨버터142 A / D Converter
144, 244 메모리144, 244 memory
145, 245 D/A컨버터145, 245 D / A Converter
150 데이터 드라이버150 data drivers
160, 260 전류 싱크160, 260 current sink
216 판독트랜지스터216 read transistor
220 변동치 보정부220 fluctuation correction part
242 전류 측정부242 Current measuring unit

Claims (16)

  1. 유기발광 표시장치의 휘도 편차 보상장치로,As a luminance deviation compensation device of an organic light emitting display device,
    제 1 전극과 제 2 전극 및 게이트 전극을 갖는 구동 트랜지스터와,A driving transistor having a first electrode, a second electrode, and a gate electrode;
    상기 구동 트랜지스터의 상기 제 1 전극과 접속되는 제 1 전압 원과,A first voltage source connected to the first electrode of the driving transistor;
    상기 구동 트랜지스터의 상기 제 2 전극에 애노드 전극이 접속된 유기전계 발광소자와,An organic light emitting diode having an anode connected to the second electrode of the driving transistor;
    제 2 전압 원과,With a second voltage source,
    상기 유기전계 발광소자의 캐소드 전극을 상기 제 2 전압 원과 전류 싱크 사이에서 선택적으로 접속하는 선택 스위치와,A selection switch for selectively connecting the cathode of the organic light emitting element between the second voltage source and the current sink;
    상기 구동 트랜지스터의 상기 게이트 전극에 시험전압이 인가된 때에 상기 제 1 전압 원으로부터 상기 전류 싱크로 흐르는 전류를 측정하는 전류측정회로를 포함하는 휘도 편차 보상장치.And a current measurement circuit for measuring a current flowing from the first voltage source to the current sink when a test voltage is applied to the gate electrode of the driving transistor.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 유기발광 표시장치는 n행 m열의 복수의 화소 회로를 구비하고,The organic light emitting display device includes a plurality of pixel circuits of n rows and m columns,
    복수의 화소 회로 각각의 유기전계 발광소자의 캐소드 전극은 상호 접속된 공통 캐소드 전극을 통해서 상기 선택 스위치와 선택적으로 접속되는 휘도 편차 보상장치.And a cathode electrode of each of the plurality of pixel circuits is selectively connected to the selection switch through an interconnected common cathode electrode.
  3. 청구항 1에 있어서,The method according to claim 1,
    상기 전류측정회로는 아날로그 디지털 컨버터를 포함하는 휘도 편차 보상장치.The current measurement circuit comprises a luminance deviation compensation device including an analog-to-digital converter.
  4. 청구항 3에 있어서,The method according to claim 3,
    상기 전류측정회로는 로패스 필터를 더 포함하는 휘도 편차 보상장치.The current measuring circuit further comprises a low pass filter.
  5. 청구항 1 내지 4 중 어느 한 항의 휘도 편차 보상장치에 의한 휘도 편차 보상방법으로,Claims 1 to 4 of the luminance deviation compensation method by the luminance deviation compensation device,
    상기 선택스위치를 상기 전류 싱크 측으로 전환하는 단계와,Switching the selection switch to the current sink side;
    상기 전류측정회로를 이용하여 상기 제 1 전압 원에서 상기 전류 싱크로 흐르는 전류를 측정하는 단계와,Measuring a current flowing from the first voltage source to the current sink using the current measuring circuit;
    측정된 상기 전류로부터 상기 유기발광 표시장치의 휘도 편차를 보상하는 단계를 포함하는 휘도 편차 보상방법.Compensating for the luminance deviation of the organic light emitting display device from the measured current.
  6. 청구항 5에 있어서,The method according to claim 5,
    상기 전류를 측정하는 단계는,Measuring the current,
    상기 유기발광 표시장치를 표시장치로서 사용하기 전에 실행하는 제 1 단계와,A first step of performing the organic light emitting display device before using it as a display device;
    상기 유기발광 표시장치를 미리 정해진 시간 동안 표시장치로서 사용한 후에 실행하는 제 2 단계로 이루어지며,And a second step of executing the organic light emitting display as a display device for a predetermined time.
    상기 휘도 편차를 보상하는 단계에서는 상기 제 1 단계에서 측정한 전류 값을 기준 전류 값으로 하여, 상기 제 2 단계에서 측정한 전류 값을 상기 기준 전류 값과 비교함으로써 휘도 편차를 보상하는 휘도 편차 보상방법.In the compensating for the luminance deviation, the luminance deviation compensation method compensates for the luminance deviation by comparing the current value measured in the second step with the reference current value using the current value measured in the first step as a reference current value. .
  7. 청구항 6에 있어서,The method according to claim 6,
    상기 제 1 단계 및 상기 제 2 단계에서 측정한 전류 값의 비교결과로부터 상기 구동 트랜지스터의 오프셋 전압을 계산하는 단계를 더 포함하며,Calculating an offset voltage of the driving transistor from a comparison result of current values measured in the first and second steps,
    상기 구동 트랜지스터의 오프셋 전압은 룩업테이블 형태로 기억되는 휘도 편차 보상방법.And an offset voltage of the driving transistor is stored in the form of a lookup table.
  8. 청구항 7에 있어서,The method according to claim 7,
    상기 휘도 편차의 보상은 상기 유기발광 표시장치에 입력하는 화상 신호를 상기 오프셋 전압에 의해 보정함으로써 이루어지는 휘도 편차 보상방법.And the compensation of the luminance deviation is performed by correcting the image signal input to the organic light emitting display by the offset voltage.
  9. n행 m열의 복수의 화소 회로와 제 1 전압 원 및 제 2 전압 원을 구비하는 유기발광 표시장치의 휘도 편차 보상장치로,A luminance deviation compensation device of an organic light emitting display device comprising a plurality of pixel circuits in n rows and m columns, and a first voltage source and a second voltage source,
    상기 복수의 화소 회로는 각각,The plurality of pixel circuits, respectively,
    구동트랜지스터와,A driving transistor,
    일단 측이 상기 제 1 전압 원과 접속되어서, 상기 구동트랜지스터가 온 되면 상기 제 1 전압 원으로부터 전압을 인가받는 유기발광소자와,An organic light emitting device that receives a voltage from the first voltage source once the side is connected to the first voltage source so that the driving transistor is turned on;
    상기 구동트랜지스터 오프 시에 선택적으로 온 되어서 상기 유기발광소자의 상기 일단 측에 전압을 인가하는 판독트랜지스터를 구비하며,A read transistor that is selectively turned on when the driving transistor is turned off to apply a voltage to the one end side of the organic light emitting element,
    상기 휘도 편차 보상장치는,The luminance deviation compensation device,
    전류 싱크와,With current sink,
    상기 유기발광소자의 타단 측을 상기 제 2 전압 원과 상기 전류 싱크 사이에서 선택적으로 접속하는 선택 스위치와,A selection switch for selectively connecting the other end of the organic light emitting element between the second voltage source and the current sink;
    상기 구동트랜지스터에 시험전압이 인가된 때에 상기 제 1 전압 원으로부터 상기 유기발광소자로 흐르는 전류를 측정하고, 상기 판독트랜지스터가 온 된 때에 상기 판독트랜지스터로부터 상기 유기발광소자로 흐르는 전류를 측정하는 전류측정회로를 포함하는 휘도 편차 보상장치.Measuring current flowing from the first voltage source to the organic light emitting diode when a test voltage is applied to the driving transistor, and measuring current flowing from the read transistor to the organic light emitting diode when the read transistor is turned on. Luminance deviation compensation device comprising a circuit.
  10. 청구항 9에 있어서,The method according to claim 9,
    상기 전류측정회로는,The current measuring circuit,
    상기 유기발광소자에 흐르는 전류를 측정하는 전류측정수단과,Current measuring means for measuring a current flowing in the organic light emitting device;
    상기 전류측정수단이 측정한 전류 값을 기초로 상기 구동트랜지스터의 게이트 소스 간 전압 및 상기 유기발광소자의 구동전압을 연산하는 변동치 연산수단을 포함하는 휘도 편차 보상장치.And variation value calculating means for calculating the voltage between the gate source of the driving transistor and the driving voltage of the organic light emitting element based on the current value measured by the current measuring means.
  11. 청구항 10에 있어서,The method according to claim 10,
    상기 게이트 소스 간 전압 및 상기 구동전압의 측정은 유기발광 표시장치의 사용에 따른 특성의 열화 전과 당해 유기발광 표시장치의 사용에 따른 특성의 열화 후에 각각 이루어지며,The measurement of the voltage between the gate source and the driving voltage is performed before deterioration of characteristics due to the use of the organic light emitting display device and after degradation of characteristics due to the use of the organic light emitting display device.
    상기 변동치 연산수단은 상기 열화 후의 게이트 소스 간 전압 및 구동전압과 상기 열화 전의 게이트 소스 간 전압 및 구동전압으로부터 각각 당해 구동트랜지스터의 문턱 전압 변동치 및 당해 유기발광소자의 구동전압 변동치를 더 산출하는 휘도 편차 보상장치.The fluctuation value calculating means further calculates a luminance deviation of the threshold voltage variation of the driving transistor and the driving voltage variation of the organic light emitting diode from the gate-source voltage and drive voltage after the degradation and the gate-source voltage and drive voltage before the degradation, respectively. Compensator.
  12. 청구항 11에 있어서,The method according to claim 11,
    상기 휘도 편차 보상장치는 보정수단을 더 포함하고,The luminance deviation compensation device further includes a correction means,
    상기 변동치 연산수단은 상기 문턱 전압 변동치 및 상기 구동전압 변동치를 합산한 보상전압을 상기 보정수단에 제공하며,The variation value calculating means provides the correction means with a compensation voltage obtained by adding the threshold voltage variation value and the driving voltage variation value,
    상기 보정수단은 상기 보상전압을 화상 신호에 가산하여 상기 유기발광 표시장치를 구동하는 휘도 편차 보상장치.And the correction means adds the compensation voltage to an image signal to drive the organic light emitting display device.
  13. 청구항 9의 휘도 편차 보상장치에 의한 휘도 편차 보상방법으로,A luminance deviation compensation method by the luminance deviation compensation device of claim 9,
    상기 유기발광 표시장치의 사용에 따른 특성이 열화하기 전의 상기 복수의 화소 회로 각각의 구동트랜지스터의 게이트 소스 간 전압 및 유기발광소자의 구동전압을 측정하는 제 3 단계와,A third step of measuring a voltage between a gate source of a driving transistor of each of the plurality of pixel circuits and a driving voltage of an organic light emitting diode before the characteristics of the organic light emitting display are deteriorated;
    상기 유기발광 표시장치의 사용에 따른 특성이 열화한 후의 상기 복수의 화소 회로 각각의 구동트랜지스터의 게이트 소스 간 전압 및 유기발광소자의 구동전압을 측정하는 제 4 단계와,A fourth step of measuring a voltage between a gate source of a driving transistor of each of the plurality of pixel circuits and a driving voltage of an organic light emitting diode after deterioration of characteristics due to the use of the organic light emitting display device;
    상기 제 3 단계와 상기 제 4 단계에서 각각 측정한 상기 복수의 화소 회로 각각의 구동트랜지스터의 게이트 소스 간 전압 및 유기발광소자의 구동전압으로부터 복수의 화소 회로 각각의 구동트랜지스터의 문턱 전압 변동치 및 유기발광소자의 구동전압 변동치를 산출하는 제 5 단계를 포함하는 휘도 편차 보상방법.Threshold voltage variation and organic light emission of the driving transistors of each of the plurality of pixel circuits from the voltage between the gate sources of the driving transistors and the driving voltages of the organic light emitting diodes measured in the third and fourth stages, respectively. Comprising a fifth step of calculating the drive voltage fluctuation value of the device.
  14. 청구항 13에 있어서,The method according to claim 13,
    상기 제 5 단계에서 산출한 상기 문턱 전압 변동치 및 상기 구동전압 변동치를 합산하여 상기 복수의 화소 회로 각각의 보상전압을 산출하고, 상기 보상전압을 당해 화소 회로에 인가되는 화상 신호에 가산하여 상기 유기발광 표시장치를 구동하는 제 6 단계를 더 포함하는 휘도 편차 보상방법.The threshold voltage variation and the driving voltage variation calculated in the fifth step are added to calculate a compensation voltage of each of the plurality of pixel circuits, and the compensation voltage is added to an image signal applied to the pixel circuit to generate the organic light emission. And a sixth step of driving the display device.
  15. 청구항 13 또는 14에 있어서,The method according to claim 13 or 14,
    상기 제 3 단계는,The third step,
    상기 선택스위치를 상기 전류 싱크 측으로 전환하는 단계와,Switching the selection switch to the current sink side;
    상기 구동트랜지스터를 온 하고 상기 판독트랜지스터를 오프 하여, 상기 구동트랜지스터에 소정의 크기의 시험전압을 인가해서 상기 유기발광소자에 흐르는 제 1 전류를 측정하는 단계와,Measuring the first current flowing through the organic light emitting diode by turning on the driving transistor and turning off the read transistor, applying a test voltage having a predetermined magnitude to the driving transistor;
    상기 구동트랜지스터를 오프 하고 상기 판독트랜지스터를 온 하여, 상기 제 1 전류와 동일한 크기의 제 2 전류를 상기 유기발광소자에 흘리고, 이때 상기 판독트랜지스터에 인가된 인가전압을 측정하는 단계와,Turning off the driving transistor and turning on the read transistor, flowing a second current having the same magnitude as the first current to the organic light emitting element, and measuring an applied voltage applied to the read transistor;
    상기 시험전압과 상기 인가전압으로부터 당해 구동트랜지스터의 게이트 소스 간 전압과 당해 유기발광소자의 구동전압을 연산하는 단계를 포함하는 휘도 편차 보상방법.Calculating a voltage between a gate source of the driving transistor and a driving voltage of the organic light emitting diode from the test voltage and the applied voltage.
  16. 청구항 13 또는 14에 있어서,The method according to claim 13 or 14,
    상기 제 4 단계는,The fourth step,
    상기 선택스위치를 상기 전류 싱크 측으로 전환하는 단계와,Switching the selection switch to the current sink side;
    상기 구동트랜지스터를 온 하고 상기 판독트랜지스터를 오프 하여, 상기 제 3 단계에서 상기 구동트랜지스터의 게이트 소스 간 전압 측정시에 상기 발광소자에 흐른 전류 값과 동일한 크기의 제 4 전류를 흘리고, 이때 상기 구동트랜지스터에 인가된 시험전압을 측정하는 단계와,By turning on the driving transistor and turning off the read transistor, in the third step, a fourth current having the same magnitude as that of the current flowing in the light emitting device is measured when the voltage between the gate and source of the driving transistor is measured. In this case, the driving transistor Measuring a test voltage applied to the;
    상기 구동트랜지스터를 오프 하고 상기 판독트랜지스터를 온 하여, 상기 제 3 전류와 동일한 크기의 제 4 전류를 상기 유기발광소자에 흘리고, 이때 상기 판독트랜지스터에 인가된 인가전압을 측정하는 단계와,Turning off the driving transistor and turning on the read transistor, flowing a fourth current having the same magnitude as the third current to the organic light emitting element, and measuring an applied voltage applied to the read transistor;
    상기 시험전압과 상기 인가전압으로부터 당해 구동트랜지스터의 게이트 소스 간 전압과 당해 유기발광소자의 구동전압을 연산하는 단계를 포함하는 휘도 편차 보상방법.Calculating a voltage between a gate source of the driving transistor and a driving voltage of the organic light emitting diode from the test voltage and the applied voltage.
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