WO2013171938A1 - 表示装置 - Google Patents
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- WO2013171938A1 WO2013171938A1 PCT/JP2013/000902 JP2013000902W WO2013171938A1 WO 2013171938 A1 WO2013171938 A1 WO 2013171938A1 JP 2013000902 W JP2013000902 W JP 2013000902W WO 2013171938 A1 WO2013171938 A1 WO 2013171938A1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/131—Interconnections, e.g. wiring lines or terminals
- H10K59/1315—Interconnections, e.g. wiring lines or terminals comprising structures specially adapted for lowering the resistance
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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
- G09G3/3233—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 current through the light-emitting element
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/121—Active-matrix OLED [AMOLED] displays characterised by the geometry or disposition of pixel elements
- H10K59/1213—Active-matrix OLED [AMOLED] displays characterised by the geometry or disposition of pixel elements the pixel elements being TFTs
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/121—Active-matrix OLED [AMOLED] displays characterised by the geometry or disposition of pixel elements
- H10K59/1216—Active-matrix OLED [AMOLED] displays characterised by the geometry or disposition of pixel elements the pixel elements being capacitors
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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
- 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
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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
- 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
- G09G2300/0852—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor being a dynamic memory with more than one capacitor
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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
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0243—Details of the generation of driving signals
- G09G2310/0251—Precharge or discharge of pixel before applying new pixel voltage
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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
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0262—The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
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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
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0233—Improving the luminance or brightness uniformity across the screen
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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
- G09G2320/00—Control of display operating conditions
- G09G2320/04—Maintaining the quality of display appearance
- G09G2320/043—Preventing or counteracting the effects of ageing
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/131—Interconnections, e.g. wiring lines or terminals
Definitions
- the present invention relates to an active matrix display device using a current-driven light emitting element typified by organic EL, and more particularly to image quality improvement of the display device.
- Image display devices using organic electroluminescence (EL) elements are known as image display devices using current-driven light emitting elements.
- the organic EL display device using the self-emitting organic EL element does not require a backlight necessary for a liquid crystal display device, and is optimal for thinning the device.
- the organic EL element used in the organic EL display device is different from the liquid crystal cell being controlled by the voltage applied thereto, in that the luminance of each light emitting element is controlled by the value of current flowing therethrough.
- organic EL elements constituting pixels are usually arranged in a matrix.
- a switching thin film transistor (TFT) is provided at the intersection of a plurality of scanning lines and a plurality of data lines, a gate electrode of a driving element is connected to the switching TFT, and the switching TFT is turned on through the selected scanning line.
- a data signal is input to the drive element from the data line.
- a device in which an organic EL element is driven by this drive element is called an active matrix type organic EL display device.
- an active matrix organic EL display device it is necessary to accurately write a data voltage reflecting a video signal in a pixel circuit in order to realize high-precision image display. That is, since the driving element passes a driving current corresponding to the data voltage to the light emitting element, it is necessary to accurately write the data voltage between the gate and the source of the driving element.
- Patent Document 1 discloses an image display device having a circuit configuration for accurately writing a data voltage reflecting a video signal to a pixel in order to realize a highly accurate image display.
- FIG. 13 is a diagram showing a circuit configuration of a pixel included in the image display device described in Patent Document 1.
- the pixel 510 in the figure includes a switch transistor 511, 512 and 519, an electrostatic storage capacitor 513, a drive transistor 514, an organic EL element 515, a data line 516, scanning lines 517 and 518, and a reference power supply line 520. And a positive power supply line 521 and a negative power supply line 522.
- a data voltage writing operation and a light emitting operation in the circuit configuration will be described.
- the scanning line driver circuit 504 turns on the switch transistors 511 and 512 with the switch transistor 519 turned off. Accordingly, the reference voltage VREF of the reference power supply line 520 is applied to the electrode 531, and the data voltage Vdata is applied to the electrode 532 from the data line 516. At this time, since the drain electrode current of the drive transistor 514 does not flow, the organic EL element 515 does not emit light. In this data voltage writing period, only a capacitive load is connected to the reference power supply line 520, so that a voltage drop due to a steady current does not occur. Therefore, accurate potentials VREF and Vdata corresponding to the data voltage are written into the electrode 531 and the electrode 532 of the electrostatic storage capacitor 513, respectively.
- the scanning line driver circuit 504 turns off the switch transistors 511 and 512 to turn off the electrode 531 and the reference power supply line 520 and turn off the electrode 532 and the data line 516. .
- the scanning line driving circuit 504 turns on the switch transistor 519 to make the source electrode of the driving transistor 514 and the electrode 532 conductive.
- the electrode 531 is disconnected from the reference power supply line 520, and the electrode 532 is disconnected from the data line 516. Therefore, the gate potential of the drive transistor 514 changes with the variation of the source potential, and (VREF ⁇ Vdata) that is the voltage across the electrostatic holding capacitor 513 is applied between the gate and the source.
- a signal current corresponding to ⁇ Vdata) flows through the organic EL element 515, and the light emission operation is executed.
- an object of the present invention is to provide a display device in which image quality is improved by a simple pixel circuit.
- a display device is a display device including a display portion in which a plurality of light emitting pixels are arranged, and each of the plurality of light emitting pixels includes a first power line. And a second power line, a source electrode and a drain electrode are disposed on a current path between the first power line and the second power line, and a current on the current path according to a gate-source voltage.
- the second electrode is electrically connected to the source electrode of the driving transistor, so that a capacitive element that holds a gate-source voltage of the driving transistor, and the first electrode of the capacitive element
- a first switch element for switching conduction and non-conduction between one of the second electrodes and a data line transmitting a data voltage corresponding to luminance, and the other of the first electrode and the second electrode of the capacitive element
- a second switch element for applying a reference voltage, and in each of the plurality of light emitting pixels, the first power line voltage as the voltage of the first power line and the voltage of the second power line as described above.
- the potential difference from the second power supply line voltage decreases as it becomes the center of the display unit, and the reference voltage in each of the plurality of light emitting pixels is the first power supply line voltage or the second power supply line in the light emitting pixel. It is set according to the voltage.
- the display device of the present invention since the voltage obtained by adding the voltage drop of the power supply line to the data voltage is written to the light emitting pixel, the luminance at the center of the screen where the voltage drop is larger than that at the periphery of the screen is increased. can do. Therefore, it is possible to provide a display device having an image quality that is relatively brighter at the center of the screen than at the periphery of the screen.
- FIG. 1 is a block diagram showing an electrical configuration of a display device of the present invention.
- FIG. 2 is a diagram showing a circuit configuration of a pixel included in the display unit according to the embodiment of the present invention and a connection with a peripheral circuit thereof.
- FIG. 3A is an operation timing chart of the driving method of the display device according to the embodiment of the present invention.
- FIG. 3B is an operation timing chart showing a modification of the display device driving method according to the embodiment of the present invention.
- FIG. 4 is an operation flowchart of the display device according to the embodiment of the present invention.
- FIG. 5A is a diagram illustrating a conduction state of the pixel circuit when data voltage is written in the display device according to the embodiment of the present invention.
- FIG. 5A is a diagram illustrating a conduction state of the pixel circuit when data voltage is written in the display device according to the embodiment of the present invention.
- FIG. 5B is a diagram illustrating a conduction state of the pixel circuit during light emission of the display device according to the embodiment of the present invention.
- FIG. 6 is a graph comparing the luminance of the display device according to the embodiment of the present invention and the conventional display device.
- FIG. 7 is a circuit layout diagram of a pixel according to the embodiment of the present invention.
- FIG. 8 is a circuit layout diagram showing a modification of the pixel according to the embodiment of the present invention.
- FIG. 9A is a circuit diagram showing a first modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 9B is a circuit diagram illustrating a second modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 9C is a circuit diagram showing a third modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10A is a circuit diagram showing a fourth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10B is a circuit diagram illustrating a fifth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10C is a circuit diagram illustrating a sixth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10D is a circuit diagram illustrating a seventh modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 11A is a circuit diagram showing an eighth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10A is a circuit diagram showing a fourth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10B is a circuit diagram illustrating a fifth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 10C is a circuit diagram illustrating
- FIG. 11B is a circuit diagram illustrating a ninth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 11C is a circuit diagram showing a tenth modification of the pixel circuit according to the embodiment of the present invention.
- FIG. 12 is an external view of a thin flat TV incorporating the display device of the present invention.
- FIG. 13 is a diagram illustrating a circuit configuration of a pixel included in the image display device described in Patent Document 1.
- FIG. 14A is a diagram illustrating a conduction state of the pixel circuit at the time of writing in the conventional image display device described in Patent Document 1.
- FIG. 14B is a diagram illustrating a conduction state of the pixel circuit during light emission of the conventional image display device described in Patent Document 1.
- FIG. 14A is a diagram showing a conduction state of the pixel circuit at the time of writing in the conventional image display device described in Patent Document 1. The writing operation to the pixel will be described with reference to FIG.
- the switch transistors 511 and 512 are turned on by the scanning signal of the scanning line 517. Since the electrostatic holding capacitor 513 is connected to the data line 516 and the reference power supply line 520, the electrostatic holding capacitor 513 holds a voltage of (VREF ⁇ Vdata). At this time, since the driving transistor 514 and the switch transistor 519 are in a non-conductive state, no steady current flows through the positive power supply line 521, the negative power supply line 522, the reference power supply line 520, and the data line 516. As a result, an accurate voltage corresponding to the data voltage is held at both ends of the electrostatic holding capacitor 513 that holds a voltage to be applied between the gate and source of the driving transistor 514.
- FIG. 14B is a diagram illustrating a conduction state of the pixel circuit during light emission of the conventional image display device described in Patent Document 1. The light emission operation of the pixel will be described with reference to FIG.
- the switch transistors 511 and 512 are turned off by the scanning signal of the scanning line 517.
- the electrostatic storage capacitor 513 is not electrically connected to the data line 516 and the reference power supply line 520.
- the switch transistor 519 is turned on by the scanning signal of the scanning line 518, and the electrostatic storage capacitor 513 is turned on with the gate electrode and the source electrode of the driving transistor 514.
- the voltage (VREF ⁇ Vdata) held in the electrostatic holding capacitor 513 is applied between the gate and the source of the driving transistor 514.
- Vdrop a voltage drop (rise) Vdrop is generated in the negative power supply line 522 due to the wiring resistance and drive current of the negative power supply line 522. That is, the potential VEEp of the negative power supply line 522 in the pixel 510 is as follows.
- the drive current flows through the organic EL element 515, so that the source potential of the drive transistor 514 does not drop with the negative power supply line 522.
- the source potential is usually the negative power supply line 522 potential + the anode-cathode voltage of the organic EL element 515, but the potential drops by Vdrop from the normal source potential due to the voltage drop Vdrop.
- the potential rises.
- the gate electrode of the driving transistor 514 since the gate electrode of the driving transistor 514 is in a floating state, the gate potential rises according to the variation of the source potential.
- the gate potential variation ⁇ Vg of the driving transistor 514 is Vdrop ⁇ Cs / (Cs + Cpara) with respect to the source potential variation Vdrop.
- Cs is a capacitance value of the electrostatic holding capacitor 513. Therefore, the gate-source voltage Vgs of the drive transistor 514 is as follows from the voltage (VREF ⁇ Vdata) held in the electrostatic holding capacitor 513, the gate voltage variation ⁇ Vg and the source voltage variation ⁇ Vs. .
- Vgs at the start of light emission decreases from the write voltage (VREF ⁇ Vdata) by (Cpara / Cs + Cpara) ⁇ Vdrop due to the voltage drop (rise) of the negative power supply line 522.
- the drive current Id flowing through the organic EL element 515 is expressed as follows.
- ⁇ and Vth are the mobility and threshold voltage of the driving transistor 514, respectively. From Equation 3, the drive current Id also decreases, so that the light emission luminance of the organic EL element 515 decreases. As a result, the central portion of the pixel where the voltage drop (rise) is large becomes dark.
- the central portion of the screen becomes dark due to the voltage drop of the power supply line, and it is difficult to maintain high image quality. Since the viewer's line of sight concentrates on the center of the screen, the display panel can be improved in image quality by making the center of the screen brighter than the periphery.
- a display device is a display device including a display portion in which a plurality of light-emitting pixels are arranged, and each of the plurality of light-emitting pixels includes a first portion.
- a power supply line, a second power supply line, a source electrode and a drain electrode are disposed on a current path between the first power supply line and the second power supply line, and on the current path according to a gate-source voltage.
- a driving transistor for driving the current, an anode electrode and a cathode electrode arranged on the current path, a light emitting element that emits light in response to the current, and a first electrode electrically connected to the gate electrode of the driving transistor And the second electrode is electrically connected to the source electrode of the drive transistor, whereby a capacitive element that holds a gate-source voltage of the drive transistor, and the first of the capacitive element A first switch element that switches between conduction and non-conduction between one of the electrode and the second electrode and a data line that transmits a data voltage corresponding to luminance; and the other of the first electrode and the second electrode of the capacitive element And a second switch element for applying a reference voltage, and a first power line voltage and a voltage of the second power line which are voltages of the first power line in each of the plurality of light emitting pixels.
- the potential difference from the second power supply line voltage decreases as it becomes the center of the display unit, and the reference voltage in each of the plurality of light emitting pixels is the first power supply line voltage or the second power supply in the light emitting pixel. It is set according to the line voltage.
- the data voltage is applied to one of the first electrode and the second electrode of the capacitive element that can be connected to the source electrode of the drive transistor via the first switch element.
- the voltage of the power supply line that varies in voltage depending on the pixel position is applied to the other of the first electrode and the second electrode of the capacitor that can be connected to the gate electrode of the transistor via the second switch element.
- the center of the screen where the voltage drop (rise) amount of the power supply line due to the wiring resistance and current is larger than that in the screen periphery. Therefore, the center of the screen where the viewer's line of sight tends to concentrate can be set brighter than the periphery of the screen, and high image quality can be provided.
- circuit wiring can be simplified. Thereby, the miniaturization of pixels is promoted, and the display panel can be made high definition.
- the driving transistor is n-type, the drain electrode and the source electrode of the driving transistor, and an anode electrode and a cathode electrode of the light emitting element.
- the reference voltage is the second power supply line voltage in the light emitting pixel
- the first switch element is connected between the second electrode of the capacitor and the data line. The second switch element may switch between conduction and non-conduction between the first electrode of the capacitive element and the second power supply line.
- the driving transistor is n-type, the drain electrode and the source electrode of the driving transistor, and an anode electrode and a cathode electrode of the light emitting element.
- the reference voltage is the first power supply line voltage in the light emitting pixel
- the first switch element is connected between the first electrode of the capacitor and the data line.
- the second switch element may switch between conduction and non-conduction between the second electrode of the capacitive element and the first power supply line.
- the data voltage is applied to the first electrode of the capacitive element that can be connected to the gate electrode of the n-type drive transistor when writing the data voltage with the first and second switch elements in the conductive state
- the voltage of the first power supply line having a negative potential fluctuation is applied to the source electrode of the type driving transistor.
- the gate-source voltage of the drive transistor at the start of light emission becomes a voltage larger than an accurate voltage corresponding to the data voltage.
- the voltage drop amount of the first power supply line is larger in the central portion of the screen than in the peripheral portion of the screen, the light emission luminance in the central portion of the screen can be relatively increased.
- the driving transistor is p-type, the source electrode and the drain electrode of the driving transistor, and an anode electrode and a cathode electrode of the light emitting element.
- the reference voltage is the first power supply line voltage in the light emitting pixel
- the first switch element is connected between the second electrode of the capacitor and the data line. The second switch element may switch between conduction and non-conduction between the first electrode of the capacitive element and the first power supply line.
- the driving transistor is p-type, the source electrode and the drain electrode of the driving transistor, and an anode electrode and a cathode electrode of the light emitting element.
- the reference voltage is the second power supply line voltage in the light emitting pixel
- the first switch element is connected between the first electrode of the capacitor and the data line.
- the second switch element may switch between conduction and non-conduction between the second electrode of the capacitive element and the second power supply line.
- each of the plurality of light emitting pixels may further include a third switch element that switches between conduction and non-conduction between the source electrode of the driving transistor and the second electrode of the capacitor.
- the third switch element becomes non-conductive, so that it is possible to cut off a path for generating a steady current other than the charging operation of the capacitor element during the writing period. Therefore, accurate voltages corresponding to the data voltage and the power supply line voltage are written into the first electrode and the second electrode of the capacitor.
- the third switch element is turned on at the start of light emission, the voltage held in the capacitor element is applied between the gate and the source of the driving transistor, so that the light emitting element is set to the data voltage and the power line voltage. Emits light with the corresponding brightness.
- the drive transistor may be an enhancement type.
- the driving transistor when the driving transistor is, for example, n-type, the second power supply line voltage is applied to the gate electrode of the driving transistor when the data voltage is written, but the source electrode of the driving transistor is applied to the second power supply line voltage.
- a voltage larger than the light emission threshold voltage of the organic EL element is applied, and a voltage of 0 V or less is applied between the gate electrode and the source electrode of the driving transistor. Therefore, if the threshold voltage of the driving transistor is an enhancement type greater than 0V, the driving transistor is turned off. Therefore, at this time, since the drain current of the driving transistor does not flow, the organic EL element does not emit light.
- the display device is a display device including a display portion in which a plurality of light emitting pixels are arranged, and each of the plurality of light emitting pixels includes a first power supply line and a second power supply line.
- a source transistor and a drain electrode disposed on a current path between the first power supply line and the second power supply line, and driving a current on the current path according to a gate-source voltage;
- the anode electrode and the cathode electrode are disposed on the current path, and have a light emitting element that emits light according to the current, a first electrode, and a second electrode, and the first electrode serves as a gate electrode of the driving transistor.
- a first capacitor element which is electrically connected and the second electrode is electrically connected to the source electrode of the drive transistor to hold a gate-source voltage of the drive transistor;
- a reference voltage is applied to the first switch element that switches between conduction and non-conduction between the first electrode of the capacitive element and a data line that transmits a data voltage corresponding to luminance, and the first electrode of the first capacitive element
- a second switch element for switching, a source electrode of the drive transistor, and a fourth switch element for switching between conduction and non-conduction with the anode electrode of the light emitting element, and in each of the plurality of light emitting pixels,
- the potential difference between the first power supply line voltage, which is the voltage of the first power supply line, and the second power supply line voltage, which is the voltage of the second power supply line decreases toward the center of the display unit, and the plurality of light emission
- the reference voltage in each pixel is set according to the first power line voltage or the second power line voltage in the light emitting pixel.
- the reference voltage is the first power supply line voltage in the light emitting pixel
- a fifth switch element for applying an initialization voltage to the source electrode or the drain electrode of the driving transistor is provided. You may prepare.
- the reference voltage is the first power supply line voltage in the light emitting pixel, and further includes a third electrode and a fourth electrode, and the third electrode is the second capacitor of the first capacitor.
- the fourth electrode may be connected to an electrode, and the fourth electrode may be connected to an initialization voltage line that can be set to an initialization voltage.
- the power supply line voltage of the first power supply line in which a voltage drop has occurred is applied to the first electrode of the first capacitive element via the second switch element.
- the source potential of the driving transistor becomes a potential obtained by subtracting the absolute value of the voltage drop amount of the first power supply line.
- the display device includes a display unit in which a plurality of light emitting pixels are arranged, and each of the plurality of light emitting pixels includes a first power supply line, a second power supply line, a source electrode, and a drain electrode.
- a driving transistor disposed on a current path between the first power line and the second power line and driving a current on the current path according to a gate-source voltage; an anode electrode; and a cathode electrode, A first light-emitting element that is disposed on a current path and emits light in response to the current, a first electrode and a second electrode, and the second electrode is electrically connected to the source electrode of the driving transistor.
- Connected second A first switching element that switches between conduction and non-conduction between a quantity element, the third electrode of the second capacitance element, and a data line that transmits a data voltage corresponding to luminance; and the first capacitance element of the first capacitance element
- the potential difference between the first power supply line voltage that is the voltage of the first power supply line and the second power supply line voltage that is the voltage of the second power supply line decreases as it becomes the center of the display unit.
- the reference voltage in each of the plurality of light emitting pixels may be set according to the first power supply line voltage or the second power supply line voltage in the light emitting
- the reference voltage is the second power supply line voltage in the light emitting pixel, and further includes a seventh switch element for applying an initialization voltage to the second electrode of the first capacitor element. May be.
- the power supply line voltage of the second power supply line in which a voltage rise is generated via the second switch element is applied to the first electrode of the first capacitive element.
- the voltage across the first capacitive element becomes a potential obtained by adding the absolute value of the voltage increase amount of the power supply line.
- the first capacitor element is connected to the gate electrode of the driving transistor, so that the light emission luminance at the center of the screen where the amount of voltage increase is larger than that at the periphery of the screen is relatively high. Therefore, the central portion of the screen is brighter than the peripheral portion of the screen, and high image quality can be provided.
- the second power supply line is a common electrode in which one of the anode electrode and the cathode electrode of the light emitting element is formed in common with the plurality of light emitting pixels, and at least one of the plurality of light emitting pixels.
- One light emitting pixel may have a connection point where one of the source electrode and the drain electrode of the second switch element is electrically connected to the common electrode corresponding to the light emitting pixel.
- the potential of the common electrode is applied to the electrode to which the data voltage is not applied, of the two electrodes of the capacitive element by the conduction of the second switch element.
- the pixel interval at which the connection point is provided can be determined according to the degree of potential fluctuation of the common electrode.
- connection point may be provided for each of the plurality of light emitting pixels.
- the light emission luminance of the light emitting pixel can be changed with high accuracy according to the position of the light emitting pixel in the display unit.
- connection point may be provided in common for two or more adjacent light emitting pixels among the plurality of light emitting pixels.
- the light emission luminance of the light emitting pixel can be changed for each unit pixel.
- the common electrode may be formed of a conductive metal oxide.
- the common electrode has a sheet resistance of 1 ⁇ / sq. You may form with the above material.
- the common electrode made of a metal oxide has a higher resistance than a highly conductive metal electrode. Therefore, the change of the voltage drop (rise) amount according to the position in the display part of a common electrode becomes larger than the change of the voltage drop (rise) amount of a metal electrode. Therefore, it is possible to set a significant change in light emission luminance according to the position of the display unit.
- FIG. 1 is a block diagram showing an electrical configuration of a display device of the present invention.
- the display device 1 in the figure includes a control circuit 2, a scanning line driving circuit 4, a signal line driving circuit 5, and a display unit 6.
- FIG. 2 is a diagram showing a circuit configuration of a pixel included in the display unit according to Embodiment 1 of the present invention and a connection with peripheral circuits thereof.
- the pixel 10 in the figure includes a switch transistor 11, 12 and 19, an electrostatic storage capacitor 13, a drive transistor 14, an organic EL element 15, a data line 16, scanning lines 17 and 18, and a positive power supply line 21. And a negative power supply line 22.
- the peripheral circuit is a light emitting pixel including a scanning line driving circuit 4 and a signal line driving circuit 5.
- the control circuit 2 outputs a control signal based on the video signal input from the outside to the scanning line driving circuit 4 and the signal line driving circuit 5.
- the scanning line driving circuit 4 is connected to the scanning lines 17 and 18, and drives the conduction and non-conduction of the switch transistors 11, 12 and 19 of the pixel 10 by outputting scanning signals to the scanning lines 17 and 18. Circuit.
- the signal line drive circuit 5 is connected to the data line 16 and is a drive circuit that outputs a data voltage based on the video signal to the pixel 10.
- the display unit 6 includes a plurality of pixels 10 arranged in a matrix, and displays an image based on a video signal input from the outside to the display device 1.
- the positive power supply line 21 is a first power supply line disposed at least for each pixel row or each pixel column
- the negative power supply line 22 is a second power supply line disposed at least for each pixel row or each pixel column.
- a power supply voltage is applied to the ends of the positive power supply line 21 and the negative power supply line 22 from a power supply provided outside the display unit 6.
- a voltage drop corresponding to the wiring resistance of the power supply line occurs from the periphery of the display panel toward the center of the positive power supply line 21, and the power supply line of the negative power supply line 22 extends from the periphery of the display panel toward the center.
- a voltage rise corresponding to the wiring resistance occurs. That is, the power supply line voltage VDDp that is the voltage of the positive power supply line 21 and the power supply line voltage VEEp that is the voltage of the negative power supply line in each of the plurality of pixels 10 differ depending on the position of the pixel 10 in the display unit 6.
- the switch transistor 11 has a gate electrode connected to the scanning line 17 arranged for each pixel row, one of the source electrode and the drain electrode connected to the data line 16 arranged for each pixel column, and the source electrode and the drain electrode.
- the other is the first switch element connected to the electrode 132 which is the second electrode of the electrostatic holding capacitor 13.
- the switch transistor 11 has a function of switching between conduction and non-conduction between the data line 16 that transmits a data voltage corresponding to luminance and the electrode 132.
- the gate electrode is connected to the scanning line 17, one of the source electrode and the drain electrode is connected to the negative power supply line 22, and the other of the source electrode and the drain electrode is the first electrode of the electrostatic storage capacitor 13.
- the second switch element is connected to the electrode 131 and applies a reference voltage to the electrode 131.
- the switch transistor 12 has a function of determining the timing of applying the power supply line voltage VEEp of the negative power supply line 22 to the electrode 131 of the electrostatic holding capacitor 13 by switching between conduction and non-conduction between the electrode 131 and the negative power supply line 22. Have. That is, the reference voltage in each pixel 10 is the power supply line voltage VEEp of the negative power supply line 22 in the pixel 10.
- the switch transistors 11 and 12 are composed of, for example, n-type thin film transistors (n-type TFTs).
- the electrostatic storage capacitor 13 is a capacitive element in which the electrode 131 is connected to the gate electrode of the drive transistor 14 and the electrode 132 is connected to the source electrode of the drive transistor 14 via the switch transistor 19.
- the electrostatic storage capacitor 13 holds a voltage corresponding to the data voltage supplied from the data line 16, and stabilizes the gate-source voltage of the drive transistor 14 after the switch transistors 11 and 12 are turned off, for example.
- the current supplied from the drive transistor 14 to the organic EL element 15 is stabilized.
- the drive transistor 14 is a drive element having a drain electrode connected to the positive power supply line 21 and a source electrode connected to the anode of the organic EL element 15.
- the drive transistor 14 converts the gate-source voltage into a drain current corresponding to the voltage. Then, this drain current is supplied to the organic EL element 15 as a signal current.
- the drive transistor 14 is composed of, for example, an n-type thin film transistor (n-type TFT). That is, the drive transistor 14 has a source electrode and a drain electrode arranged on a current path between the positive power supply line 21 and the negative power supply line 22 and drives a current on the current path in accordance with a gate-source voltage. .
- the organic EL element 15 is a light emitting element in which an anode electrode and a cathode electrode are arranged on the current path, and a cathode electrode is connected to the negative power supply line 22, and the signal current flows through the driving transistor 14. Emits light.
- the drain electrode and the source electrode of the drive transistor 14 and the anode electrode and the cathode electrode of the organic EL element 15 are arranged in this order from the positive power supply line 21 on the current path.
- the switch transistor 19 has a gate electrode connected to the scanning line 18 arranged for each pixel row, one of the source electrode and the drain electrode is connected to the source electrode of the drive transistor 14, and the other of the source electrode and the drain electrode is electrostatic.
- the third switch element is connected to the electrode 132 of the storage capacitor 13.
- the switch transistor 19 switches the conduction and non-conduction between the source electrode of the driving transistor 14 and the electrode 132 of the electrostatic holding capacitor 13, thereby changing the voltage held in the electrostatic holding capacitor 13 between the gate and the source of the driving transistor 14.
- the timing to apply to is determined.
- the switch transistor 19 is composed of, for example, an n-type thin film transistor (n-type TFT).
- the data line 16 is connected to the signal line driving circuit 5 and connected to each pixel belonging to the pixel column including the pixel 10 and supplies a data voltage for determining the light emission intensity.
- the display device 1 includes data lines 16 corresponding to the number of pixel columns.
- the scanning line 17 is connected to the scanning line driving circuit 4 and is connected to each pixel belonging to the pixel row including the pixel 10. Accordingly, the scanning line 17 supplies the timing for writing the data voltage to each pixel belonging to the pixel row including the pixel 10, and supplies the timing for applying the power supply line voltage VEEp to the gate electrode of the driving transistor 14 of the pixel. To do.
- the scanning line 18 is connected to the scanning line driving circuit 4. Accordingly, the scanning line 18 supplies timing for applying the potential of the electrode 132 of the electrostatic storage capacitor 13 to the source electrode of the driving transistor 14.
- the display device 1 includes scanning lines 17 and 18 corresponding to the number of pixel rows.
- the positive power supply line 21 and the negative power supply line 22 are also connected to other pixels, and are connected to power supplies arranged in the peripheral region of the display unit 6. It is connected.
- FIG. 3A is an operation timing chart of the display device driving method according to Embodiment 1 of the present invention.
- the horizontal axis represents time.
- waveform diagrams of voltages generated in the scanning line 17, the scanning line 18, and the data line 16 are shown in order from the top.
- FIG. 4 is an operation flowchart of the display device according to Embodiment 1 of the present invention.
- the scanning line driving circuit 4 changes the voltage level of the scanning line 18 from HIGH to LOW to turn off the switch transistor 19.
- the source electrode of the driving transistor 14 and the electrode 132 (second electrode) of the electrostatic storage capacitor 13 become non-conductive (S11 in FIG. 4).
- HIGH of the voltage level of the scanning line 18 is set to + 20V, and LOW is set to ⁇ 10V.
- FIG. 5A is a diagram illustrating a conduction state of the pixel circuit when data voltage is written in the display device according to Embodiment 1 of the present invention.
- the power supply line voltage VEEp of the negative power supply line 22 is applied to the electrode 131 of the electrostatic storage capacitor 13, and the data voltage Vdata is applied to the electrode 132 via the data line 16. . That is, in step S ⁇ b> 12, the electric charge corresponding to the data voltage to be applied to the pixel 10 is held in the electrostatic holding capacitor 13.
- the source electrode and the electrode 132 of the driving transistor 14 are non-conductive due to the operation in step S11. Further, the power supply line voltage VEEp of the negative power supply line 22 is applied to the gate electrode of the drive transistor 14, and at this time, the source electrode of the drive transistor 14 is organic with respect to the power supply line voltage VEEp of the negative power supply line 22. A voltage corresponding to the light emission threshold voltage of the EL element 15 is applied, and a voltage of 0 V or less is applied between the gate electrode and the source electrode of the drive transistor 14. Therefore, if the threshold voltage Vth of the drive transistor 14 is larger than 0V (enhancement type), the drive transistor 14 is turned off.
- the organic EL element 15 does not emit light.
- HIGH of the voltage level of the scanning line 17 is set to + 20V, and LOW is set to ⁇ 10V.
- the data voltage Vdata is applied from the data line 16 to the electrode 132 of the pixel 10, and each of the pixels belonging to the pixel row including the pixel 10 is similarly applied. A data voltage is supplied to the pixel.
- the scanning line driving circuit 4 changes the voltage level of the scanning line 17 from HIGH to LOW to turn off the switch transistors 11 and 12.
- the electrode 131 (first electrode) and the negative power supply line 22 (second power supply line) become non-conductive
- the electrode 132 (second electrode) and the data line 16 become non-conductive (FIG. 4). S13).
- FIG. 5B is a diagram illustrating a conduction state of the pixel circuit during light emission of the display device according to Embodiment 1 of the present invention.
- the source electrode of the drive transistor 14 and the electrode 132 (second electrode) of the electrostatic storage capacitor 13 are electrically connected (S14 in FIG. 4).
- the electrode 131 of the electrostatic storage capacitor 13 is disconnected from the negative power supply line 22, and the electrode 132 is disconnected from the data line 16. Therefore, the gate potential of the driving transistor 14 changes with the variation of the source potential, and (VEEp ⁇ Vdata) that is the voltage across the electrostatic holding capacitor 13 is applied between the gate and the source.
- Vdrop a voltage drop (rise) Vdrop is generated in the negative power supply line 22 due to the wiring resistance and drive current of the negative power supply line 22. That is, the potential VEEp of the negative power supply line 22 is as follows.
- the source potential of the drive transistor 14 does not drop with the negative power supply line 22.
- the source potential is normally the negative power supply line potential VEEp + the voltage between the anode and cathode of the organic EL element 15, but the potential rises by Vdrop from the normal source potential due to the voltage drop Vdrop) To do.
- the gate electrode of the driving transistor 14 is in a floating state, the gate potential rises according to the variation of the source potential.
- the parasitic capacitance 30 exists equivalently between the gate and drain of the driving transistor 14 and the capacitance value of the parasitic capacitance 30 is Cpara.
- the variation ⁇ Vg of the gate potential of the driving transistor 14 is ⁇ Vdrop ⁇ Cs / (Cs + Cpara) ⁇ with respect to the variation Vdrop of the source potential.
- Cs is a capacitance value of the electrostatic holding capacitor 13. Therefore, the gate-source voltage Vgs of the driving transistor 14 is as follows from the voltage (VEEp-Vdata) held in the electrostatic holding capacitor 13, the gate voltage variation ⁇ Vg, and the source voltage variation ⁇ Vs. .
- Vgs at the start of light emission is larger by ⁇ Vgs expressed by Equation 6 above than the accurate writing voltage. Further, ⁇ Vgs increases as the voltage drop (increase) Vdrop in the negative power supply line 22 increases.
- the drive current flowing through the organic EL element 15 is expressed as follows.
- ⁇ and Vth are the mobility and threshold voltage of the drive transistor 14, respectively. From Equation 7, the drive current Id also increases, and as a result, the light emission luminance of the organic EL element 15 increases. Further, the light emission luminance of the organic EL element 15 increases as the voltage drop (rise) Vdrop increases.
- a power supply for supplying voltage to the positive power supply line 21 and the negative power supply line 22 is disposed outside the display unit 6, and the power supply voltage is supplied from the power supply to the power supply line located on the outermost periphery of the display unit 6. .
- the potential of the positive power supply line 21 decreases as it goes toward the center of the display unit 6, and the potential of the negative power supply line 22 increases as it goes toward the center of the display unit 6. That is, the potential difference between the positive power supply line 21 and the negative power supply line 22 becomes smaller toward the center of the display unit 6. Therefore, the pixel central portion where the voltage drop (rise) is large (the potential difference is small) becomes bright.
- the source potential of the drive transistor 14 changes from 0V to 10V due to the conduction of the switch transistor 19. Further, the voltage VDD of the positive power supply line is set to + 20V, and the power supply line voltage VEEp of the negative power supply line 22 is set to 0V.
- FIG. 6 is a graph comparing the luminance of the display device according to the embodiment of the present invention and the conventional display device.
- the horizontal axis represents ⁇ Vdrop which is the amount of voltage drop (rise) in the negative power supply line 22, and the vertical axis represents the case where there is no voltage drop (rise) in the negative power supply line 22 as the reference luminance. This represents the rate of change in luminance.
- the luminance change rates of the display device 1 (4T1C4W) according to the present embodiment and the conventional image display device (4T1C5W) are compared.
- 4T1C4W means that, for example, four transistors of the drive transistor 14 and the switch transistors 11, 12, and 19 are represented as 4T, the electrostatic holding capacitor 13 is represented as 1C, the positive power supply line 21, the data line 16, and the scanning line.
- the four wirings 17 and 18 are represented as 4W.
- 4T1C5W represents, for example, four transistors of the drive transistor 514 and the switch transistors 511, 512, and 519 as 4T, the electrostatic storage capacitor 513 as 1C, the positive power supply line 521, the data line 516, and the scanning line 17 And 18 and the five wirings of the reference power supply line 520 are expressed as 5 W.
- the rate of change in luminance decreases as ⁇ Vdrop increases.
- the rate of change in luminance increases as ⁇ Vdrop increases.
- the period from t0 to t4 corresponds to one frame period in which the light emission intensity of all the pixels included in the display device 1 is updated, and the operation in the period from t0 to t4 is repeated after t4.
- FIG. 3B is an operation timing chart showing a modification of the display device driving method according to Embodiment 1 of the present invention.
- the scanning line driving circuit 4 simultaneously performs the operation at time t0 described in FIG. 3A and the operation at time t1 described in FIG. 3A (S11 and S12 in FIG. 4). . That is, the source electrode of the driving transistor 14 and the electrode 132 are rendered non-conductive, and at the same time, the power supply voltage VEEp is applied to the electrode 131 and the data voltage Vdata is applied to the electrode 132.
- the scanning line driving circuit 4 simultaneously executes the operation at time t2 described in FIG. 3A and the operation at time t3 described in FIG. 3A (S13 and S14 in FIG. 4). ). That is, the electrode 131 and the negative power supply line 22 become non-conductive, the electrode 132 and the data line 16 become non-conductive, and the source electrode of the drive transistor 14 and the electrode 132 become conductive.
- Vgs varies from the write voltage (VEEp ⁇ Vdata) to the above equation 5 due to the voltage drop (rise) of the negative power supply line 22.
- Vgs expressed by the above equation 5 is continuously applied between the gate and the source, and the current Id expressed by the above equation 7 flows, whereby the organic EL element 15 continues to emit light. .
- the period from t10 to t12 corresponds to one frame period in which the emission intensity of all the pixels of the display device 1 is updated, and the operation in the period from t10 to t12 is repeated after t12.
- the data voltage Vdata is applied to the electrode 132 that can be connected to the source electrode of the drive transistor 14 via the switch transistor 11 when the data voltage is written.
- the power supply line voltage VEEp of the negative power supply line 22 in which the voltage drop (rise) occurs is applied to the electrode 131 that can be connected to the gate electrode of the drive transistor 14.
- a voltage obtained by adding the absolute value of the voltage drop (rise) amount Vdrop of the power supply line to the absolute value of the data voltage Vdata is written in the electrostatic holding capacitor 13, and corresponds to the data voltage Vdata at the start of light emission.
- the display device 1 according to Embodiment 1 of the present invention is brighter in the center of the screen than in the periphery of the screen, and can provide high image quality.
- the timing at time t3 and time t4 of the scanning line 18 is controlled independently of the timing of the scanning line 17, thereby emitting light within one frame period.
- Time, that is, duty control can be arbitrarily adjusted.
- the scanning lines 17 and 18 are interlocked. Accordingly, since the scanning line control circuit is simplified, the circuit scale can be reduced.
- the switch transistor 11 and the switch transistor 12 are n (p) type and the switch transistor 19 is p (n) type, Although the number of outputs of the scanning line driving circuit 4 can be reduced by using the scanning lines 17 and 18 as the same wiring, the duty control is not possible and almost 100% of the period excluding the data voltage writing period within one frame period. Sustained luminescence.
- FIG. 7 is a circuit layout diagram of the pixel according to the embodiment of the present invention.
- a circuit diagram of the pixel 10 is shown on the left side
- a top perspective view of the drive circuit layer is shown in the center
- a top perspective view of the light emitting layer is shown on the right side. Since FIG. 7 shows a top emission type circuit layout diagram, the drive circuit layer is in the lower layer and the light emitting layer is in the upper layer.
- the drive circuit layer including circuit elements other than the organic EL element 15 and the negative power supply line 22 in the pixel 10 includes a GM (gate metal) layer, an SD (source / drain) layer, and an Si (semiconductor) layer.
- the drive transistor 14 and the switch transistors 11, 12, and 19 are formed of bottom gate electrode type thin film transistors. Therefore, the GM layer is the lower layer, the SD layer is the upper layer, and the Si layer is the intermediate layer.
- the gate electrode of each transistor, the electrode 131 of the electrostatic storage capacitor 13, the scanning lines 17 and 18, and the positive power supply line 21 (lateral direction) are arranged.
- the source electrode and drain electrode of each transistor, the electrode 132 of the electrostatic storage capacitor 13, the data line 16, and the positive power supply line (vertical direction) are arranged.
- the light emitting layer including the organic EL element 15 and the negative power supply line 22 in the pixel 10 includes an AM (anode metal) layer, a BNK (bank) layer, and a transparent cathode layer (not shown).
- the AM layer is the lower layer
- the BNK layer is the intermediate layer
- the transparent electrode layer is the upper layer.
- the anode electrode of the organic EL element is disposed in the AM layer
- the cathode electrode and the negative power line 22 of the organic EL element are disposed in the transparent electrode layer.
- the negative power supply line 22 is not a wiring provided for each pixel, but is formed of a transparent cathode film formed on the entire surface of the display unit 6.
- the negative power supply line 22 coincides with the cathode electrode of the organic EL element 15, and the cathode electrode is a common electrode formed in common for all the pixels 10.
- the cathode electrode is a common electrode formed in common for all the pixels 10.
- a bank for separating the organic light emitting layer for each pixel is arranged.
- the drive circuit layer and the light emitting layer are electrically connected via a connection point A between the anode electrode of the organic EL element 15 and the source electrode of the drive transistor 14.
- the connection point A is configured by a contact hole that connects the SD layer and the AM layer.
- the connection point B between the negative power supply line 22 and one of the source electrode and the drain electrode of the switch transistor 12, which is the main part of the present invention, is constituted by a contact hole connecting the SD layer and the transparent cathode layer.
- the SD layer and the transparent electrode layer are connected by a transparent electrode layer, an AM layer (area without bank), a contact hole connecting the AM layer and the SD layer, and a connection point B.
- connection point B is arranged for each pixel. Thereby, the light emission luminance of the pixel 10 can be changed with high accuracy according to the pixel position in the display unit 6.
- the connection point B is connected to the uppermost transparent cathode, the pixel opening serving as the light emitting region is limited.
- a layout for suppressing a decrease in pixel aperture ratio will be described.
- FIG. 8 is a circuit layout diagram showing a modification of the pixel according to the embodiment of the present invention.
- the circuit layout shown in FIG. 7 has a connection point B connecting one of the source electrode and the drain electrode of the switch transistor 12 and the negative power supply line 22 for each pixel. It is different in that it is not arranged.
- the adjacent red pixel 10R, green pixel 10G, and blue pixel 10B are set as one unit pixel, and a contact hole that configures a connection point B for each unit pixel is formed. Is provided. That is, the connection point B is provided in common for two or more adjacent pixels.
- a large difference in voltage drop (rise) amount is not observed between a plurality of adjacent pixels. Therefore, even if the connection point B is provided for each unit pixel as described above, the center of the screen is more than the periphery of the screen. The effect of the present invention that the lighter becomes brighter is achieved. In addition, the layout configuration of the present modification suppresses a decrease in the aperture ratio due to contact holes.
- the pixel interval at which the connection point B is provided can be determined according to the degree of potential fluctuation of the common electrode.
- the negative power supply line 22 that is a common electrode may be formed of a conductive metal oxide.
- the negative power supply line 22 has a sheet resistance of 1 ⁇ / sq. It is preferable to form with the above material.
- a common electrode made of a metal oxide has a higher resistance than a highly conductive metal electrode. Thereby, the change of the voltage drop (rise) amount according to the position in the display part of a common electrode becomes larger than the change of the voltage drop (rise) amount of a metal electrode. Therefore, it is possible to set a significant change in light emission luminance according to the position of the display unit.
- circuit configuration of the pixel included in the display device 1 of the present invention is not limited to the circuit configuration illustrated in FIG.
- the pixel circuit configuration of the display device of the present invention will be exemplified.
- FIG. 9A is a circuit diagram showing a first modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10NS shown in the figure is only different from the circuit configuration of the pixel 10 shown in FIG. 2 in that a switch element 41 is arranged instead of the switch transistor 19 and the scanning line 18. Is different.
- the following description will focus on differences from the circuit configuration of the pixel 10 illustrated in FIG.
- the switch element 41 has one end connected to the source electrode of the drive transistor 14 and the other end connected to the electrode 132 and the anode electrode of the organic EL element 15, and has a function of flowing or blocking the drive current of the drive transistor 14. .
- the switch element 41 is constituted by, for example, a thin film transistor having a gate electrode connected to the scanning line 18.
- the drive timing of the switch element 41 is the same as that of the switch transistor 19 of the pixel 10 shown in FIG.
- the display device in which the pixels 10NS are arranged in a matrix by the circuit configuration and the drive timing has the same effect as the display device 1 according to the above embodiment.
- FIG. 9B is a circuit diagram illustrating a second modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10NG1 shown in the figure includes switch transistors 11, 12, and 19, an electrostatic storage capacitor 13, a drive transistor 14, an organic EL element 15, a data line 16, and scanning lines 17 and 18.
- the gate electrode is connected to the scanning line 17, one of the source electrode and the drain electrode is connected to the data line 16, and the other of the source electrode and the drain electrode is the electrode 131 (first electrode) of the electrostatic storage capacitor 13. ) Connected to the first switch element.
- the switch transistor 11 has a function of determining the timing of applying the data voltage of the data line 16 to the electrode 131 by switching between conduction and non-conduction between the electrode 131 and the data line 16.
- the gate electrode is connected to the scanning line 17, one of the source electrode and the drain electrode is connected to the positive power supply line 21 (first power supply line), and the other of the source electrode and the drain electrode is the electrostatic storage capacitor 13.
- the second switch element is connected to the electrode 132 (second electrode).
- the switch transistor 12 has a function of determining the timing of applying the power supply line voltage VDDp of the positive power supply line 21 in the pixel 10 to the electrode 132 by switching between conduction and non-conduction between the electrode 132 and the positive power supply line 21.
- the switch transistors 11 and 12 are composed of, for example, n-type thin film transistors (n-type TFTs).
- the electrostatic storage capacitor 13 is a capacitive element in which the electrode 131 is connected to the gate electrode of the drive transistor 14 and the electrode 132 is connected to the anode electrode of the organic EL element 15 through the switch transistor 19.
- the electrostatic storage capacitor 13 holds a voltage corresponding to the data voltage supplied from the data line 16, and stabilizes the gate-source voltage of the drive transistor 14 after the switch transistors 11 and 12 are turned off, for example. The current supplied from the drive transistor 14 to the organic EL element 15 is stabilized.
- the drive transistor 14 is a drive element having a drain electrode connected to the positive power supply line 21 and a source electrode connected to one end of the switch element 41.
- the drive transistor 14 converts the gate-source voltage into a drain electrode current corresponding to the voltage. Then, this drain electrode current is supplied to the organic EL element 15 as a signal current.
- the drive transistor 14 is composed of, for example, an n-type thin film transistor (n-type TFT).
- the organic EL element 15 is a light emitting element having a cathode connected to the negative power supply line 22, and emits light when the signal current flows through the drive transistor 14 and the switch element 41.
- the drain electrode and the source electrode of the drive transistor 14 and the anode electrode and the cathode electrode of the organic EL element 15 are arranged on the current path between the positive power supply line 21 and the negative power supply line 22 in this order.
- the gate electrode is connected to the scanning line 18, one of the source electrode and the drain electrode is connected to the anode electrode of the organic EL element 15, and the other of the source electrode and the drain electrode is the electrode 132 of the electrostatic storage capacitor 13. Is a third switch element connected to.
- the switch transistor 19 determines the timing at which the voltage held in the electrostatic holding capacitor 13 is applied between the gate and the source of the drive transistor 14 in conjunction with the switch element 41.
- the switch transistor 19 is composed of, for example, an n-type thin film transistor (n-type TFT).
- the other end of the switch element 41 is connected to one of the source electrode and the drain electrode of the switch transistor 19 and the anode electrode of the organic EL element 15, and has a function of flowing or blocking the drive current of the drive transistor 14.
- the switch element 41 includes a thin film transistor in which a gate electrode is connected to a scanning line. In this circuit configuration, when the data voltage is written, the switch element 41 is turned on by applying the data voltage Vdata to the gate electrode of the drive transistor 14 so that the drive transistor 14 is turned on and the drive current flows to the organic EL element 15. It is provided to prevent light emission.
- the drive timing of the switch element 41 is the same as the drive timing of the switch transistor 19.
- the data voltage Vdata is applied to the electrode 131 that can be connected to the gate electrode of the drive transistor 14 through the switch transistor 11 when the data voltage is written, and the source of the drive transistor 14
- the power supply line voltage VDDp of the positive power supply line 21 in which a voltage drop occurs is applied to the electrode 132 that can be connected to the electrode.
- a voltage obtained by adding the absolute value of the voltage drop amount of the power supply line to the absolute value of the data voltage Vdata is written in the electrostatic holding capacitor 13, so that the screen center portion having a larger voltage drop amount than the screen periphery portion is written.
- the emission luminance of the becomes relatively high. Therefore, in the display device in which the pixels 10NG1 according to the present modification are arranged in a matrix, the central portion of the screen is brighter than the peripheral portion of the screen, and high image quality can be provided.
- FIG. 9C is a circuit diagram showing a third modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10NG2 illustrated in FIG. 9 is different from the circuit configuration of the pixel 10NG1 illustrated in FIG. 9B in that the switch transistor 19 and the scanning line 18 are not provided and the connection position of the switch element 41 is different.
- the description will focus on differences from the circuit configuration of the pixel 10NG1 illustrated in FIG. 9B.
- the switch element 41 has one end connected to the source electrode of the drive transistor 14 and the electrode 132 of the electrostatic storage capacitor 13, and the other end connected to the anode electrode of the organic EL element 15.
- the switch element 41 becomes non-conductive at the time of writing the data voltage, so that the current path of the positive power supply line 21 ⁇ the drive transistor 14 ⁇ the switch element 41 ⁇ the organic EL element 15 ⁇ the negative power supply line 22, and the positive power supply line 21.
- the switch element 41 has the same drive timing as that of the switch transistor 19 shown in FIG.
- the display device in which the pixels 10NG2 are arranged in a matrix by the circuit configuration and the drive timing has the same effect as the display device 1 according to the above embodiment.
- the switch transistor 19 becomes unnecessary by arranging the switch element 41 at the above position.
- FIG. 10A is a circuit diagram showing a fourth modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10PS1 shown in the figure includes p-type switch transistors 31, 32 and 39, an electrostatic storage capacitor 13, a drive transistor 34, an organic EL element 15, a data line 16, and a scanning line. 17 and 18, a positive power supply line 21, and a negative power supply line 22.
- the switch transistor 31 has a gate electrode connected to the scanning line 17, one of the source electrode and the drain electrode connected to the data line 16, and the other of the source electrode and the drain electrode connected to the electrode 131 of the electrostatic storage capacitor 13.
- the switch transistor 31 has a function of determining the timing of applying the data voltage of the data line 16 to the electrode 131 by switching between conduction and non-conduction between the electrode 131 (second electrode) of the electrostatic holding capacitor 13 and the data line 16.
- the gate electrode is connected to the scanning line 17, one of the source electrode and the drain electrode is connected to the positive power supply line 21, and the other of the source electrode and the drain electrode is connected to the electrode 132 of the electrostatic storage capacitor 13.
- the second switch element The switch transistor 32 switches the conduction and non-conduction between the electrode 132 (first electrode) of the electrostatic storage capacitor 13 and the positive power supply line 21, thereby applying the power supply line voltage VDDp of the positive power supply line 21 to the electrode 132. It has a function to determine.
- the switch transistors 31 and 32 are configured by, for example, p-type thin film transistors (p-type TFTs).
- the electrostatic storage capacitor 13 is a capacitive element in which the electrode 131 is connected to the source electrode of the driving transistor 34 and the positive power supply line 21 via the switch transistor 39, and the electrode 132 is connected to the gate electrode of the driving transistor 34.
- the electrostatic storage capacitor 13 holds a voltage corresponding to the data voltage supplied from the data line 16, and stabilizes the gate-source voltage of the drive transistor 34 after the switch transistors 31 and 32 are turned off, for example.
- the current supplied from the drive transistor 34 to the organic EL element 15 is stabilized.
- the drive transistor 34 is a drive element having a source electrode connected to the positive power supply line 21 and a drain electrode connected to the anode electrode of the organic EL element 15.
- the drive transistor 34 converts the gate-source voltage into a drain electrode current corresponding to the voltage. Then, this drain electrode current is supplied to the organic EL element 15 as a signal current.
- the drive transistor 34 is configured by a p-type thin film transistor (p-type TFT).
- the organic EL element 15 is a light emitting element having a cathode connected to the negative power supply line 22, and emits light when the signal current flows through the driving transistor 34.
- the source electrode and drain electrode of the drive transistor 34 and the anode electrode and cathode electrode of the organic EL element 15 are arranged in this order on the current path between the positive power supply line 21 and the negative power supply line 22.
- the switch transistor 39 has a gate electrode connected to the scanning line 18, one of the source electrode and the drain electrode connected to the source electrode of the driving transistor 34 and the positive power supply line 21, and the other of the source electrode and the drain electrode electrostatic capacitance.
- 13 is a third switch element connected to 13 electrodes 131.
- the switch transistor 39 determines the timing at which the voltage held in the electrostatic holding capacitor 13 is applied between the gate and source of the driving transistor 34.
- the switch transistor 39 is composed of a p-type thin film transistor (n-type TFT). When the data voltage is written, the switch transistor 39 is in a non-conductive state, thereby preventing a current from flowing through the positive power supply line 21 through the path of the electrode 131 ⁇ the switch transistor 39 ⁇ the positive power supply line 21.
- the scanning line driving circuit 4 changes the voltage level of the scanning line 18 from LOW to HIGH to turn off the switch transistor 39.
- the source electrode of the drive transistor 34 and the electrode 131 of the electrostatic storage capacitor 13 become non-conductive.
- the scanning line driving circuit 4 changes the voltage level of the scanning line 17 from HIGH to LOW to turn on the switch transistors 31 and 32.
- the power supply line voltage VDDp of the positive power supply line 21 in the pixel 10 is applied to the electrode 132 of the electrostatic storage capacitor 13, and the data voltage Vdata is applied to the electrode 131 via the data line 16.
- the source electrode of the driving transistor 34 and the electrode 131 are nonconductive.
- the power supply line voltage VDDp of the positive power supply line 21 is applied to the gate electrode of the drive transistor 34, but the drive transistor 34 is p-type, so it is set to a potential that turns off. Therefore, at this time, since the drain electrode current of the driving transistor 34 does not flow, the organic EL element 15 does not emit light.
- the scanning line driving circuit 4 changes the voltage level of the scanning line 17 from LOW to HIGH to turn off the switch transistors 31 and 32.
- the electrode 131 of the electrostatic storage capacitor 13 and the negative power supply line 22 become non-conductive
- the electrode 132 of the electrostatic storage capacitor 13 and the data line 16 become non-conductive.
- the scanning line driving circuit 4 changes the voltage level of the scanning line 18 from HIGH to LOW, and turns on the switch transistor 39.
- the source electrode of the drive transistor 34 and the electrode 131 of the electrostatic storage capacitor 13 are electrically connected.
- the electrode 132 of the electrostatic storage capacitor 13 is disconnected from the positive power supply line 21, and the electrode 131 is disconnected from the data line 16. Therefore, the gate potential of the driving transistor 34 changes with the variation of the source potential, and (Vdata ⁇ VDDp) that is the voltage across the electrostatic holding capacitor 13 is applied between the gate and the source.
- the potential VDDp of the positive power supply line 21 is as follows when the power supply voltage is VDD.
- the source potential of the drive transistor 34 when the drive current flows through the organic EL element 15, the source potential of the drive transistor 34 also drops to (VDD ⁇ Vdrop) together with the positive power supply line 21. .
- the gate electrode of the driving transistor 34 since the gate electrode of the driving transistor 34 is in a floating state, the gate potential drops in accordance with the variation of the source potential.
- the capacitance value of the parasitic capacitance is Cpara.
- the variation ⁇ Vg in the gate potential of the driving transistor 34 is ⁇ Vdrop ⁇ Cs / (Cs + Cpara) with respect to the variation in the source potential ⁇ Vdrop.
- the source-gate voltage Vsg of the driving transistor 34 is as follows from the voltage (Vdata ⁇ VDDp) held in the electrostatic holding capacitor 13, the gate voltage variation ⁇ Vg and the source voltage variation ⁇ Vs. .
- Vsg at the start of light emission varies from the write voltage (Vdata ⁇ VDDp) to the above equation 9 due to the voltage drop of the positive power supply line 21. Since the accurate write voltage is (Vdata ⁇ VDD), the variation ⁇ Vsg of Vgs from the accurate write voltage is as follows.
- Vsg at the start of light emission is larger by ⁇ Vsg expressed by the above equation 10 than the accurate writing voltage. Further, ⁇ Vsg increases as the voltage drop Vdrop in the positive power supply line 21 increases.
- the drive current flowing through the organic EL element 15 is expressed as follows.
- ⁇ and Vth are the mobility and threshold voltage of the drive transistor 34, respectively. From Equation 11, the drive current Id also increases, and as a result, the light emission luminance of the organic EL element 15 increases. Further, the light emission luminance of the organic EL element 15 increases as the voltage drop Vdrop increases. Therefore, the central part of the pixel having a large voltage drop becomes bright.
- the above-described data voltage writing and light emission period correspond to one frame period in which the light emission intensity of all the pixels is updated, and the above operation is repeated thereafter.
- the timing for writing the data voltage by changing the scanning line 17 from HIGH to LOW, the electrode 131 and the source electrode of the driving transistor 34 by changing the scanning line 18 from LOW to HIGH. May be performed simultaneously with the timing of turning off and off.
- the timing at which the scanning line 17 is changed from LOW to HIGH and the writing of the data voltage is finished may be simultaneously performed with the timing at which the scanning line 18 is changed from HIGH to LOW to start light emission.
- the data voltage Vdata is applied to the electrode 131 that can be connected to the source electrode of the drive transistor 34 via the switch transistor 31 when the data voltage is written.
- the power supply line voltage VDDp of the positive power supply line 21 in which a voltage drop has occurred is applied to the electrode 132 that can be connected to the gate electrode of the transistor 34.
- a voltage obtained by adding the absolute value of the voltage drop amount of the power supply line to the absolute value of the data voltage Vdata is written in the electrostatic holding capacitor 13, so that the screen center portion having a larger voltage drop amount than the screen periphery portion is written.
- the emission luminance of the becomes relatively high. Therefore, the central portion of the screen is brighter than the peripheral portion of the screen, and high image quality can be provided.
- FIG. 10B is a circuit diagram illustrating a fifth modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10PS2 shown in the figure is different from the circuit configuration of the pixel 10PS1 shown in FIG. 10A in that switch elements 41 and 42 are arranged instead of the switch transistor 39 and the scanning line 18. The point is different. In the following, the description will be focused on differences from the circuit configuration of the pixel 10PS1 illustrated in FIG. 10A.
- the switch element 41 has one end connected to the source electrode of the drive transistor 34 and the other end connected to the electrode 131, and has a function of flowing or blocking the drive current of the drive transistor 34.
- the switch element 42 has one end connected to the positive power supply line 21 and the other end connected to the electrode 131, and has a function of flowing or blocking the drive current of the drive transistor 34.
- the switch elements 41 and 42 are composed of, for example, a thin film transistor in which a gate electrode is connected to a scanning line.
- the switch element 41 when the data voltage is written, the switch element 41 is turned on when the power supply line voltage VDDp is applied to the gate electrode of the drive transistor 34, so that the data line 16 ⁇ the switch transistor 31 ⁇ It is provided to prevent current from flowing through the path of the drive transistor 34 ⁇ the organic EL element 15.
- the switch element 42 is provided in order to prevent the power supply line voltage VDDp from being applied from the positive power supply line 21 to the electrode 131 when the data voltage is written. Therefore, the drive timing of the switch elements 41 and 42 is the same as the drive timing of the switch transistor 39 in FIG. 10A.
- the display device in which the pixels 10PS2 are arranged in a matrix by the circuit configuration and the drive timing has the same effect as the display device 1 according to the above embodiment.
- FIG. 10C is a circuit diagram illustrating a sixth modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10PG1 shown in the figure includes switch transistors 31, 32, and 39, an electrostatic holding capacitor 13, a drive transistor 34, an organic EL element 15, a data line 16, and scanning lines 17 and 18.
- the gate electrode is connected to the scanning line 17, one of the source electrode and the drain electrode is connected to the data line 16, and the other of the source electrode and the drain electrode is connected to the electrode 132 of the electrostatic storage capacitor 13.
- the switch transistor 31 has a function of determining the timing of applying the data voltage of the data line 16 to the electrode 132 by switching between conduction and non-conduction between the electrode 132 (first electrode) of the electrostatic storage capacitor 13 and the data line 16.
- the gate electrode is connected to the scanning line 17, one of the source electrode and the drain electrode is connected to the negative power supply line 22, and the other of the source electrode and the drain electrode is connected to the electrode 131 of the electrostatic storage capacitor 13.
- the second switch element The switch transistor 32 switches the conduction and non-conduction between the electrode 131 (second electrode) of the electrostatic storage capacitor 13 and the negative power supply line 22, so that the power supply line voltage VEEp of the negative power supply line 22 in the pixel 10PG 1 is applied to the electrode 131. It has a function of determining the timing of application.
- the switch transistors 31 and 32 are p-type thin film transistors (n-type TFTs).
- the electrostatic storage capacitor 13 is a capacitive element in which the electrode 132 is connected to the gate electrode of the drive transistor 34 and the electrode 131 is connected to the source electrode of the drive transistor 34 via the switch transistor 39.
- the electrostatic storage capacitor 13 holds a voltage corresponding to the data voltage supplied from the data line 16, and stabilizes the source-gate voltage of the drive transistor 34, for example, after the switch transistors 31 and 32 are turned off. The current supplied from the drive transistor 34 to the organic EL element 15 is stabilized.
- the drive transistor 34 is a drive element having a source electrode connected to the positive power supply line 21 and a drain electrode connected to one end of the switch element 41.
- the drive transistor 34 converts the source-gate voltage into a drain electrode current corresponding to the voltage. Then, this drain electrode current is supplied to the organic EL element 15 as a signal current.
- the drive transistor 34 is configured by a p-type thin film transistor (p-type TFT).
- the organic EL element 15 is a light emitting element having a cathode connected to the negative power supply line 22, and emits light when the signal current flows through the driving transistor 34 and the switch element 41.
- the source electrode and drain electrode of the drive transistor 34 and the anode electrode and cathode electrode of the organic EL element 15 are arranged in this order on the current path between the positive power supply line 21 and the negative power supply line 22.
- the gate electrode is connected to the scanning line 18, one of the source electrode and the drain electrode is connected to the source electrode of the driving transistor 34, and the other of the source electrode and the drain electrode is connected to the electrode 131 of the electrostatic storage capacitor 13. It is the connected 3rd switch element.
- the switch transistor 39 works in conjunction with the switch element 41 to determine the timing at which the voltage held in the electrostatic holding capacitor 13 is applied between the gate and source of the drive transistor 34.
- the switch transistor 39 is composed of a p-type thin film transistor (p-type TFT).
- the other end of the switch element 41 is connected to the anode electrode of the organic EL element 15 and has a function of flowing or blocking the drive current of the drive transistor 34.
- the switch element 41 includes a thin film transistor in which a gate electrode is connected to a scanning line.
- the switching element 41 applies the data voltage Vdata to the gate electrode of the driving transistor 34 to turn on the driving transistor 34 and the driving current flows to the organic EL element 15. It is provided to prevent light emission.
- the switch transistor 39 is provided in order to prevent a current from flowing through the path of the positive power supply line 21 ⁇ the switch transistor 39 ⁇ the switch transistor 32 ⁇ the negative power supply line 22 when the data voltage is written. Therefore, the drive timing of the switch element 41 is the same as the drive timing of the switch transistor 39.
- the data voltage Vdata is applied to the electrode 132 that can be connected to the gate electrode of the drive transistor 34 via the switch transistor 31 when the data voltage is written, and the source of the drive transistor 34
- the power supply line voltage VEEp of the negative power supply line 22 in which a voltage drop has occurred is applied to the electrode 131 that can be connected to the electrode.
- a voltage obtained by adding the absolute value of the voltage drop amount of the power supply line to the absolute value of the data voltage Vdata is written in the electrostatic holding capacitor 13, so that the screen center portion having a larger voltage drop amount than the screen periphery portion is written.
- the emission luminance of the becomes relatively high. Therefore, in the display device in which the pixels 10PG1 according to this modification are arranged in a matrix, the center of the screen is brighter than the periphery of the screen, and high image quality can be provided.
- FIG. 10D is a circuit diagram illustrating a seventh modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10PG2 illustrated in the figure is different from the circuit configuration of the pixel 10PG1 illustrated in FIG. 10C in that the switch transistor 39 and the scanning line 18 are not provided, and the connection position of the switch element 41 is different.
- the description will be focused on differences from the circuit configuration of the pixel 10PG1 illustrated in FIG. 10C.
- the switch element 41 has one end connected to the positive power supply line 21 and the other end connected to the electrode 131 and the source electrode of the drive transistor 34.
- the switch element 41 becomes non-conductive when the data voltage is written, so that the current path of the positive power supply line 21 ⁇ the switch element 41 ⁇ the drive transistor 14 ⁇ the organic EL element 15 ⁇ the negative power supply line 22 and the positive power supply line 21.
- the switch element 41 ⁇ the electrode 131 ⁇ the switch transistor 32 ⁇ the negative power line 22 has a function of cutting off the current path.
- the drive timing of the switch element 41 is the same as that of the switch transistor 39 described in FIG. 10C.
- the display device in which the pixels 10PG2 are arranged in a matrix by the circuit configuration and the drive timing has the same effect as the display device 1 according to the above embodiment. Note that, since the switch element 41 is arranged at the above position, the switch transistor 39 becomes unnecessary.
- FIG. 11A is a circuit diagram showing an eighth modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10NH1 shown in the figure includes switch transistors 11, 51 and 54, an electrostatic storage capacitor 13, a drive transistor 14, an organic EL element 15, a data line 16, and a positive power supply line 21.
- the negative power supply line 22 and switch elements 52 and 53 are provided.
- the switch transistor 11 is a first switch element in which one of a source electrode and a drain electrode is connected to the data line 16 and the other of the source electrode and the drain electrode is connected to an electrode 131 (first electrode) of the electrostatic storage capacitor 13. is there.
- the switch transistor 11 has a function of determining the timing of applying the data voltage of the data line 16 to the electrode 131 by switching between conduction and non-conduction between the electrode 131 and the data line 16.
- the switch transistor 51 one of the source electrode and the drain electrode is connected to the positive power supply line 21 (first power supply line), and the other of the source electrode and the drain electrode is connected to the electrode 131 (first electrode) of the electrostatic storage capacitor 13.
- the switch transistor 51 has a function of determining the timing of applying the power supply line voltage VDDp of the positive power supply line 21 in the pixel 10NH1 to the electrode 131 by switching between conduction and non-conduction between the electrode 131 and the positive power supply line 21.
- the switch transistors 11 and 51 are configured by, for example, n-type thin film transistors (n-type TFTs).
- the electrostatic storage capacitor 13 is a first capacitor element in which the electrode 131 is connected to the gate electrode of the driving transistor 14 and the electrode 132 is connected to the source electrode of the driving transistor 14.
- the electrostatic holding capacitor 13 holds a voltage corresponding to the data voltage supplied from the data line 16.
- the electrostatic storage capacitor 13 stably holds the gate-source voltage of the drive transistor 14 after the switch transistors 11 and 51 are turned off, and supplies current to the organic EL element 15 from the drive transistor 14. To stabilize.
- the drive transistor 14 is a drive element having a drain electrode connected to one end of the switch element 52 and a source electrode connected to one end of the switch element 53.
- the drive transistor 14 converts the gate-source voltage into a drain current corresponding to the voltage. Then, this drain current is supplied to the organic EL element 15 as a signal current.
- the drive transistor 14 is composed of, for example, an n-type thin film transistor (n-type TFT).
- the switch element 53 is a fourth switch element that switches between conduction and non-conduction between the source electrode of the drive transistor 14 and the anode electrode of the organic EL element 15.
- the organic EL element 15 is a light emitting element having a cathode connected to the negative power supply line 22 and an anode electrode connected to one end of the switch element 53, and the signal current flows through the drive transistor 14 and the switch element 53. Emits light.
- the drain electrode and the source electrode of the drive transistor 14 and the anode electrode and the cathode electrode of the organic EL element 15 are arranged on the current path between the positive power supply line 21 and the negative power supply line 22 in this order.
- one of the source electrode and the drain electrode is connected to the source electrode of the drive transistor 14, the electrode 132 of the electrostatic storage capacitor 13, and the other end of the switch element 53, and the initialization voltage is applied to the source electrode of the drive transistor 14.
- the switch transistor 51 is turned on, and the power supply line voltage VDDp of the positive power supply line 21 is applied to the gate electrode of the drive transistor 14 and the electrode 131 of the electrostatic storage capacitor 13.
- the switch transistor 11 and the switch element 53 are off.
- the threshold voltage Vth of the drive transistor 14 is held in the electrostatic holding capacitor 13, but a voltage obtained by subtracting the absolute value of the voltage drop amount of the power supply line is applied to the electrode 131.
- the electrode 132 of the screen pixel 10NH1 in the part has a lower potential than the electrode 132 of the screen pixel 10NH1 in the peripheral part by a voltage drop.
- the switch transistor 11 is turned on, the switch transistor 51 is turned off, and the data voltage of the data line 16 is applied to the gate electrode of the drive transistor 14 and the electrode 131 of the electrostatic storage capacitor 13.
- the gate-source voltage of the driving transistor 14 is larger in the screen pixel 10NH1 in the central portion of the screen than in the peripheral screen pixel 10NH1 due to the source potential set in the threshold voltage compensation period.
- the organic EL element 15 emits light according to the gate-source voltage of the drive transistor 14.
- the power supply line voltage VDDp of the positive power supply line 21 in which a voltage drop has occurred is applied to the electrode 131 via the switch transistor 51 during threshold voltage compensation.
- the source potential of the driving transistor 14 becomes a potential obtained by subtracting the absolute value of the voltage drop amount of the power supply line.
- the display device in which the pixels 10NH1 according to the present modification are arranged in a matrix the center of the screen is brighter than the periphery of the screen, and high image quality can be provided.
- FIG. 11B is a circuit diagram illustrating a ninth modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10NH2 shown in the figure is different from the circuit configuration of the pixel 10NH1 shown in FIG. 11A in that a switch transistor 56 is arranged instead of the switch element 52, and an electrostatic The difference is that the storage capacitor 55 is arranged.
- the description will focus on the differences from the circuit configuration of the pixel 10NH1 illustrated in FIG. 11A.
- one of the source electrode and the drain electrode is connected to the source electrode of the driving transistor 14, and the other of the source electrode and the drain electrode is connected to the electrode 132 of the electrostatic storage capacitor 13.
- the electrostatic storage capacitor 55 includes a third electrode and a fourth electrode, the third electrode is connected to the electrode 132 of the electrostatic storage capacitor 13, and the fourth electrode is an initialization voltage that can be set to an initialization voltage.
- a second capacitive element connected to the line;
- the switch transistor 51 is turned on, and the power supply line voltage VDDp of the positive power supply line 21 is applied to the gate electrode of the drive transistor 14 and the electrode 131 of the electrostatic storage capacitor 13.
- the switch transistor 11 and the switch element 53 are off.
- the threshold voltage Vth of the driving transistor 14 is held in the electrostatic holding capacitor 13, but the absolute value of the voltage drop amount of the power supply line is held in the electrode 131.
- the subtracted voltage is applied.
- the electrode 132 of the screen pixel 10NH2 at the center of the screen has a lower potential than the electrode 132 of the screen pixel 10NH2 at the peripheral portion by a voltage drop.
- the switch transistor 11 is turned on, the switch transistors 51 and 56 are turned off, and the data voltage of the data line 16 is applied to the gate electrode of the drive transistor 14 and the electrode 131 of the electrostatic storage capacitor 13. Applied.
- the voltage across the electrostatic holding capacitor 13 is larger in the screen pixel 10NH2 in the center of the screen than in the peripheral screen pixel 10NH2.
- the power supply line voltage VDDp of the positive power supply line 21 in which a voltage drop has occurred is applied to the electrode 131 via the switch transistor 51 during threshold voltage compensation.
- the source potential of the driving transistor 14 and the electrode 132 become a potential obtained by subtracting the absolute value of the voltage drop amount of the power supply line.
- the light emission luminance in the central portion of the screen where the amount of voltage drop is larger than that in the peripheral portion of the screen is relatively high. Therefore, in the display device in which the pixels 10NH2 according to the present modification are arranged in a matrix, the center of the screen is brighter than the periphery of the screen, and high image quality can be provided.
- FIG. 11C is a circuit diagram showing a tenth modification of the pixel circuit according to the embodiment of the present invention.
- the circuit configuration of the pixel 10NT shown in the figure includes switch transistors 11, 58, 59 and 60, electrostatic holding capacitors 13 and 57, a drive transistor 14, an organic EL element 15, a data line 16, and a positive line.
- a power supply line 21 and a negative power supply line 22 are provided.
- the switch transistor 11 is a first switch element in which one of the source electrode and the drain electrode is connected to the data line 16 and the other of the source electrode and the drain electrode is connected to the third electrode of the electrostatic storage capacitor 57.
- the switch transistor 11 has a function of determining the timing at which the data voltage of the data line 16 is applied to the third electrode by switching between conduction and non-conduction between the third electrode and the data line 16.
- the drive transistor 14 is a drive element having a drain electrode connected to the positive power supply line 21 and a source electrode connected to the anode electrode of the organic EL element 15.
- the drive transistor 14 converts the gate-source voltage into a drain current corresponding to the voltage. Then, this drain current is supplied to the organic EL element 15 as a signal current.
- the drive transistor 14 is composed of, for example, an n-type thin film transistor (n-type TFT).
- the organic EL element 15 is a light emitting element having a cathode electrode connected to the negative power supply line 22, and emits light when the signal current flows through the driving transistor 14.
- the drain electrode and the source electrode of the drive transistor 14 and the anode electrode and the cathode electrode of the organic EL element 15 are arranged on the current path between the positive power supply line 21 and the negative power supply line 22 in this order.
- the electrostatic storage capacitor 57 is a second capacitor element that has a third electrode and a fourth electrode, and the third electrode is connected to the gate electrode of the drive transistor 14.
- the electrostatic holding capacitor 57 holds a voltage corresponding to the data voltage supplied from the data line 16, and is applied to the gate of the driving transistor 14 in the threshold voltage compensation period after the switch transistor 11 is turned off, for example.
- the capacitor portion that stably holds the voltage is configured.
- the electrostatic storage capacitor 13 is a first capacitor element in which the electrode 132 is connected to the source electrode of the drive transistor 14.
- the electrostatic storage capacitor 13 holds the voltage (corresponding to the source potential) set at the source electrode of the drive transistor 14 during the threshold voltage compensation period. For example, the switch transistor 58 is turned off and the switch transistor 60 is turned on. After that, the gate-source voltage of the drive transistor 14 is stably held, and the current supplied from the drive transistor 14 to the organic EL element 15 is stabilized.
- the switch transistor 58 In the switch transistor 58, one of the source electrode and the drain electrode is connected to the negative power supply line 22 (second power supply line), and the other of the source electrode and the drain electrode is connected to the electrode 131 (first electrode) of the electrostatic storage capacitor 13.
- the switch transistor 58 has a function of determining the timing of applying the power supply line voltage VEEp of the negative power supply line 22 in the pixel 10NT to the electrode 131 by switching between conduction and non-conduction between the electrode 131 and the negative power supply line 22.
- the switch transistors 11 and 58 are composed of, for example, n-type thin film transistors (n-type TFTs).
- the switch transistor 59 is a seventh switch element for applying an initialization voltage to the electrode 132 of the electrostatic storage capacitor 13.
- the switch transistor 60 is a sixth switch element in which one of the source electrode and the drain electrode is connected to the gate electrode of the driving transistor 14 and the other of the source electrode and the drain electrode is connected to the electrode 131 of the electrostatic storage capacitor 13.
- the switch transistor 60 is composed of, for example, an n-type thin film transistor (n-type TFT).
- the switch transistors 11 and 58 are turned on, and the data voltage ⁇ Vdata of the data line 16 is applied to the gate electrode of the drive transistor 14 and the third electrode of the electrostatic storage capacitor 57. Is done.
- the switch transistor 11 is turned off, the switch transistor 58 is turned on, and the power supply line voltage VEEp of the negative power supply line 22 is applied to the electrode 131 of the electrostatic storage capacitor 13.
- the gate-source voltage of the driving transistor 14 is set such that the screen pixel 10NT at the center of the screen has the voltage of the peripheral screen pixel 10NT by the voltage VEEp + Vdata + Vth set in the electrostatic holding capacitor 13 during the threshold voltage compensation period. Bigger than.
- the power supply line voltage VEEp of the negative power supply line 22 in which the voltage rise is generated via the switch transistor 58 is applied to the electrode 131 during the threshold voltage compensation.
- the voltage across the electrostatic auxiliary capacitor 13 becomes a potential obtained by adding the absolute value of the voltage increase amount of the power supply line.
- the electrostatic storage capacitor 13 is connected to the gate electrode of the drive transistor 14, the light emission luminance at the center of the screen where the amount of voltage increase is larger than that at the periphery of the screen is relatively high. Therefore, in the display device in which the pixels 10NT according to the present modification are arranged in a matrix, the central portion of the screen is brighter than the peripheral portion of the screen, and high image quality can be provided.
- the drive transistor and the organic EL element 15 are connected between the positive power supply line 21 and the negative power supply line 22.
- the drive transistor and the organic EL element 15 are arranged in the order of the organic EL element 15 and the drive transistor between the positive power supply line 21 and the negative power supply line 22.
- Such a configuration is also included in the scope of the present invention. That is, in the display device of the present invention, regardless of whether the driving transistor is n-type or p-type, the drain electrode and source electrode of the driving transistor and the anode electrode and cathode electrode of the organic EL element are connected to the positive power supply line 21. As long as it is arranged on the current path between the negative power supply line 22 and the negative power line 22, and the arrangement order of the driving transistor and the organic EL element is not limited.
- the switch transistors 11 and 31 (first switch element) and the switch transistors 12 and 32 (second switch element) are controlled by the same scanning line 17, but the first switch The element and the second switch element may be independently controlled on / off by different scanning lines.
- the timing of the application of the data voltage from the data line 16 to the electrostatic storage capacitor 13 and the application of the power supply line voltage from the positive power supply line or the negative power supply line to the electrostatic storage capacitor 13 are independently controlled. This also makes it possible to execute light emission duty control within one frame.
- the switch transistor has been described on the premise that the switch transistor is an FET having a gate electrode, a source electrode, and a drain electrode. However, these transistors have a base, a collector, and an emitter. Bipolar transistors may be applied. Also in this case, the object of the present invention is achieved and the same effect is produced.
- the display device according to the present invention is built in a thin flat TV as shown in FIG.
- a thin flat TV capable of displaying an image with a bright central portion of the screen while reflecting a video signal is realized.
- the present invention is particularly useful for an active organic EL flat panel display in which the luminance is varied by controlling the light emission intensity of the pixel by the pixel signal current.
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Abstract
Description
本発明者は、「背景技術」の欄において記載した画像表示装置に関し、以下の問題が生じることを見出した。
図1は、本発明の表示装置の電気的な構成を示すブロック図である。同図における表示装置1は、制御回路2と、走査線駆動回路4と、信号線駆動回路5と、表示部6とを備える。
次に、本実施の形態に係る表示装置1の駆動動作について図3A~図5Bを用いて説明する。
次に、本実施の形態に係る表示装置が有する画素10の回路構成を実現する回路素子のレイアウトについて説明する。
図9Aは、本発明の実施の形態に係る画素回路の第1の変形例を示す回路図である。同図に記載された画素10NSの回路構成は、図2に記載された画素10の回路構成と比較して、スイッチトランジスタ19及び走査線18の代わりに、スイッチ素子41が配置されている点のみが異なる。以下、図2に記載された画素10の回路構成と異なる点を中心に説明する。
図9Bは、本発明の実施の形態に係る画素回路の第2の変形例を示す回路図である。同図に記載された画素10NG1の回路構成は、スイッチトランジスタ11、12及び19と、静電保持容量13と、駆動トランジスタ14と、有機EL素子15と、データ線16と、走査線17及び18と、正電源線21と、負電源線22と、スイッチ素子41とを備える。
図9Cは、本発明の実施の形態に係る画素回路の第3の変形例を示す回路図である。同図に記載された画素10NG2の回路構成は、図9Bに記載された画素10NG1の回路構成と比較して、スイッチトランジスタ19及び走査線18が無く、スイッチ素子41の接続位置が異なる。以下、図9Bに記載された画素10NG1の回路構成と異なる点を中心に説明する。
図10Aは、本発明の実施の形態に係る画素回路の第4の変形例を示す回路図である。同図に記載された画素10PS1の回路構成は、p型のスイッチトランジスタ31、32及び39と、静電保持容量13と、駆動トランジスタ34と、有機EL素子15と、データ線16と、走査線17及び18と、正電源線21と、負電源線22とを備える。
図10Bは、本発明の実施の形態に係る画素回路の第5の変形例を示す回路図である。同図に記載された画素10PS2の回路構成は、図10Aに記載された画素10PS1の回路構成と比較して、スイッチトランジスタ39及び走査線18の代わりに、スイッチ素子41及び42が配置されている点が異なる。以下、図10Aに記載された画素10PS1の回路構成と異なる点を中心に説明する。
図10Cは、本発明の実施の形態に係る画素回路の第6の変形例を示す回路図である。同図に記載された画素10PG1の回路構成は、スイッチトランジスタ31、32及び39と、静電保持容量13と、駆動トランジスタ34と、有機EL素子15と、データ線16と、走査線17及び18と、正電源線21と、負電源線22と、スイッチ素子41とを備える。
図10Dは、本発明の実施の形態に係る画素回路の第7の変形例を示す回路図である。同図に記載された画素10PG2の回路構成は、図10Cに記載された画素10PG1の回路構成と比較して、スイッチトランジスタ39及び走査線18が無く、スイッチ素子41の接続位置が異なる。以下、図10Cに記載された画素10PG1の回路構成と異なる点を中心に説明する。
図11Aは、本発明の実施の形態に係る画素回路の第8の変形例を示す回路図である。同図に記載された画素10NH1の回路構成は、スイッチトランジスタ11、51及び54と、静電保持容量13と、駆動トランジスタ14と、有機EL素子15と、データ線16と、正電源線21と、負電源線22と、スイッチ素子52及び53とを備える。
図11Bは、本発明の実施の形態に係る画素回路の第9の変形例を示す回路図である。同図に記載された画素10NH2の回路構成は、図11Aに記載された画素10NH1の回路構成と比較して、スイッチ素子52の代わりに、スイッチトランジスタ56が配置されている点、及び、静電保持容量55が配置されている点が異なる。以下、図11Aに記載された画素10NH1の回路構成と異なる点を中心に説明する。
図11Cは、本発明の実施の形態に係る画素回路の第10の変形例を示す回路図である。同図に記載された画素10NTの回路構成は、スイッチトランジスタ11、58、59及び60と、静電保持容量13及び57と、駆動トランジスタ14と、有機EL素子15と、データ線16と、正電源線21と、負電源線22とを備える。
2 制御回路
4、504 走査線駆動回路
5、505 信号線駆動回路
6 表示部
10、10NG1、10NG2、10NS、10NH1、10NH2、10NT、10PG1、10PG2、10PS1、10PS2、510 画素
11、12、19、31、32、39、51、54、56、58、59、60、511、512、519 スイッチトランジスタ
13、55、57、513 静電保持容量
14、34、514 駆動トランジスタ
15、515 有機EL素子
16、516 データ線
17、18、517、518 走査線
21、521 正電源線
22、522 負電源線
30、530 寄生容量
41、42、52、53 スイッチ素子
131、132、531、532 電極
520 参照電源線
Claims (17)
- 複数の発光画素が配置された表示部を備える表示装置であって、
前記複数の発光画素の各々は、
第1電源線と、
第2電源線と、
ソース電極及びドレイン電極が前記第1電源線と前記第2電源線との間の電流径路上に配置され、ゲート-ソース間電圧に応じて前記電流径路上の電流を駆動する駆動トランジスタと、
アノード電極及びカソード電極が、前記電流径路上に配置され、前記電流に応じて発光する発光素子と、
第1電極及び第2電極を有し、前記第1電極が前記駆動トランジスタのゲート電極に電気的に接続され、かつ、前記第2電極が前記駆動トランジスタの前記ソース電極に電気的に接続されることにより、駆動トランジスタのゲート-ソース間電圧を保持する容量素子と、
前記容量素子の前記第1電極及び前記第2電極の一方と、輝度に対応したデータ電圧を伝達するデータ線との導通及び非導通を切り換える第1スイッチ素子と、
前記容量素子の前記第1電極及び前記第2電極の他方に、参照電圧を印加するための第2スイッチ素子とを備え、
前記複数の発光画素の各々における、前記第1電源線の電圧である第1電源線電圧と前記第2電源線の電圧である前記第2電源線電圧との電位差は、前記表示部の中央となるにつれて減少し、
前記複数の発光画素の各々における前記参照電圧は、当該発光画素における前記第1電源線電圧または前記第2電源線電圧に応じて設定されている
表示装置。 - 前記複数の発光画素のうちの少なくとも1つの発光画素において、
前記駆動トランジスタはn型であり、
前記駆動トランジスタの前記ドレイン電極及び前記ソース電極、ならびに前記発光素子のアノード電極及びカソード電極が、前記電流径路上に配置され、
前記参照電圧は、当該発光画素における前記第2電源線電圧であり、
前記第1スイッチ素子は、前記容量素子の前記第2電極と前記データ線との導通及び非導通を切り換え、
前記第2スイッチ素子は、前記容量素子の前記第1電極と前記第2電源線との導通及び非導通を切り換える
請求項1に記載の表示装置。 - 前記複数の発光画素のうちの少なくとも1つの発光画素において、
前記駆動トランジスタはn型であり、
前記駆動トランジスタの前記ドレイン電極及び前記ソース電極、ならびに前記発光素子のアノード電極及びカソード電極が、前記電流径路上に配置され、
前記参照電圧は、当該発光画素における前記第1電源線電圧であり、
前記第1スイッチ素子は、前記容量素子の前記第1電極と前記データ線との導通及び非導通を切り換え、
前記第2スイッチ素子は、前記容量素子の前記第2電極と前記第1電源線との導通及び非導通を切り換える
請求項1に記載の表示装置。 - 前記複数の発光画素のうちの少なくとも1つの発光画素において、
前記駆動トランジスタはp型であり、
前記駆動トランジスタの前記ソース電極及び前記ドレイン電極、ならびに前記発光素子のアノード電極及びカソード電極が、前記電流径路上に配置され、
前記参照電圧は、当該発光画素における前記第1電源線電圧であり、
前記第1スイッチ素子は、前記容量素子の前記第2電極と前記データ線との導通及び非導通を切り換え、
前記第2スイッチ素子は、前記容量素子の前記第1電極と前記第1電源線との導通及び非導通を切り換える
請求項1に記載の表示装置。 - 前記複数の発光画素のうちの少なくとも1つの発光画素において、
前記駆動トランジスタはp型であり、
前記駆動トランジスタの前記ソース電極及び前記ドレイン電極、ならびに前記発光素子のアノード電極及びカソード電極が、前記電流径路上に配置され、
前記参照電圧は、当該発光画素における前記第2電源線電圧であり、
前記第1スイッチ素子は、前記容量素子の前記第1電極と前記データ線との導通及び非導通を切り換え、
前記第2スイッチ素子は、前記容量素子の前記第2電極と前記第2電源線との導通及び非導通を切り換える
請求項1に記載の表示装置。 - 前記複数の発光画素の各々は、さらに、
前記駆動トランジスタのソース電極と前記容量素子の前記第2電極との導通及び非導通を切り換える第3スイッチ素子を備える
請求項1に記載の表示装置。 - 前記駆動トランジスタはエンハンスメント型である
請求項2または4に記載の表示装置。 - 複数の発光画素が配置された表示部を備える表示装置であって、
前記複数の発光画素の各々は、
第1電源線と、
第2電源線と、
ソース電極及びドレイン電極が前記第1電源線と前記第2電源線との間の電流径路上に配置され、ゲート-ソース間電圧に応じて前記電流径路上の電流を駆動する駆動トランジスタと、
アノード電極及びカソード電極が、前記電流径路上に配置され、前記電流に応じて発光する発光素子と、
第1電極及び第2電極を有し、前記第1電極が前記駆動トランジスタのゲート電極に電気的に接続され、かつ、前記第2電極が前記駆動トランジスタの前記ソース電極に電気的に接続されることにより、駆動トランジスタのゲート-ソース間電圧を保持する第1容量素子と、
前記第1容量素子の前記第1電極と、輝度に対応したデータ電圧を伝達するデータ線との導通及び非導通を切り換える第1スイッチ素子と、
前記第1容量素子の前記第1電極に、参照電圧を印加するための第2スイッチ素子と、
前記駆動トランジスタの前記ソース電極と、前記発光素子の前記アノード電極との導通及び非導通を切り換える第4スイッチ素子とを備え、
前記複数の発光画素の各々における、前記第1電源線の電圧である第1電源線電圧と前記第2電源線の電圧である前記第2電源線電圧との電位差は、前記表示部の中央となるにつれて減少し、
前記複数の発光画素の各々における前記参照電圧は、当該発光画素における前記第1電源線電圧または前記第2電源線電圧に応じて設定されている
表示装置。 - 前記参照電圧は、当該発光画素における前記第1電源線電圧であり、
さらに、前記駆動トランジスタの前記ソース電極または前記ドレイン電極に、初期化電圧を印加するための第5スイッチ素子を備える
請求項8に記載の表示装置。 - 前記参照電圧は、当該発光画素における前記第1電源線電圧であり、
さらに、第3電極及び第4電極を有し、前記第3電極が、前記第1容量素子の前記第2電極に接続され、前記第4電極が、初期化電圧に設定可能な初期化電圧線に接続された第2容量素子を備える
請求項8に記載の表示装置。 - 複数の発光画素が配置された表示部を備える表示装置であって、
前記複数の発光画素の各々は、
第1電源線と、
第2電源線と、
ソース電極及びドレイン電極が前記第1電源線と前記第2電源線との間の電流径路上に配置され、ゲート-ソース間電圧に応じて前記電流径路上の電流を駆動する駆動トランジスタと、
アノード電極及びカソード電極が、前記電流径路上に配置され、前記電流に応じて発光する発光素子と、
第1電極及び第2電極を有し、前記第2電極が前記駆動トランジスタの前記ソース電極に電気的に接続された第1容量素子と、
第3電極及び第4電極を有し、前記第3電極が前記駆動トランジスタのゲート電極に電気的に接続され、前記第4電極が前記第1容量素子の前記第1電極に電気的に接続された第2容量素子と、
前記第2容量素子の前記第3電極と、輝度に対応したデータ電圧を伝達するデータ線との導通及び非導通を切り換える第1スイッチ素子と、
前記第1の容量素子の前記第1電極に、参照電圧を印加するための第2スイッチ素子と、
前記第1容量素子の前記第1電極と、前記駆動トランジスタのゲート電極とを接続する第6スイッチ素子とを備え、
前記複数の発光画素の各々における、前記第1電源線の電圧である第1電源線電圧と前記第2電源線の電圧である前記第2電源線電圧との電位差は、前記表示部の中央となるにつれて減少し、
前記複数の発光画素の各々における前記参照電圧は、当該発光画素における前記第1電源線電圧または前記第2電源線電圧に応じて設定されている
表示装置。 - 前記参照電圧は、当該発光画素における前記第2電源線電圧であり、
さらに、前記第1容量素子の前記第2電極に、初期化電圧を印加するための第7スイッチ素子を備える
請求項11に記載の表示装置。 - 前記第2電源線は、前記発光素子の前記アノード電極及びカソード電極の一方が前記複数の発光画素に共通して形成された共通電極であり、
前記複数の発光画素のうちの少なくとも1つの発光画素は、前記第2スイッチ素子のソース電極及びドレイン電極の一方と、当該発光画素に対応する前記共通電極とが電気的に接続される接続点を有する
請求項1~12のいずれか1項に記載の表示装置。 - 前記接続点は、前記複数の発光画素のそれぞれに、1つずつ設けられている
請求項13に記載の表示装置。 - 前記接続点は、前記複数の発光画素のうち隣接する2つ以上の発光画素に共通して設けられている
請求項13に記載の表示装置。 - 前記共通電極は、導電性の金属酸化物で形成されている
請求項13に記載の表示装置。 - 前記共通電極は、シート抵抗が1Ω/sq.以上の材料で形成されている
請求項13に記載の表示装置。
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US20150053953A1 (en) | 2015-02-26 |
JPWO2013171938A1 (ja) | 2016-01-07 |
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