CN112419981B - AMOLED pixel driving circuit and driving method - Google Patents

AMOLED pixel driving circuit and driving method Download PDF

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CN112419981B
CN112419981B CN202011400063.8A CN202011400063A CN112419981B CN 112419981 B CN112419981 B CN 112419981B CN 202011400063 A CN202011400063 A CN 202011400063A CN 112419981 B CN112419981 B CN 112419981B
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thin film
film transistor
control signal
voltage
scan control
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CN112419981A (en
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谢应涛
陈鹏龙
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Chongqing University of Post and Telecommunications
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Chongqing University of Post and Telecommunications
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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
    • 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]
    • G09G3/3266—Details of drivers for scan electrodes

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of El Displays (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

The invention relates to an AMOLED pixel driving circuit and a driving method, and belongs to the technical field of display. The driving circuit directly captures the threshold voltage of the driving thin film transistor to perform threshold voltage compensation; applying the drain voltage of the sixth thin film transistor to the node A through the parallel connection of the second capacitor and the first capacitor for mobility compensation; by compensating the threshold voltage and the mobility of the driving thin film transistor, the current flowing through the organic light emitting diode is stable, the luminance of the organic light emitting diode is ensured, and the display quality of the organic light emitting diode is improved; the data voltage is input from the source electrode of the sixth thin film transistor, so that the circuit reads the data voltage while grabbing the driving thin film transistor, and the efficiency is improved; the organic light emitting diode is controlled by the signal to have current passing only in the light emitting stage, so that unnecessary light emission of the organic light emitting diode is avoided, and power consumption is reduced.

Description

AMOLED pixel driving circuit and driving method
Technical Field
The invention belongs to the technical field of display, and relates to an AMOLED pixel driving circuit and a driving method.
Background
An Organic Light Emitting Diode (OLED) Display device has many advantages of self-luminescence, low driving voltage, high luminous efficiency, short response time, high definition and contrast, a viewing angle of approximately 180 °, a wide temperature range, flexible Display, large-area full color Display, and the like, and is considered as a Display device with the most potential for development.
The OLED display device may be classified into two major categories, i.e., direct addressing and thin film transistor Matrix addressing, of a Passive Matrix OLED (PMOLED) and an Active Matrix OLED (AMOLED) according to a driving method. The AMOLED has pixels arranged in an array, belongs to an active display type, has high luminous efficiency, and is generally used as a large-sized display device with high definition.
The AMOLED is a current-driven device, and when a current flows through an organic light emitting diode, the organic light emitting diode emits light, and the luminance is determined by the current flowing through the organic light emitting diode itself. Most of the existing Integrated circuits (Integrated Circuit ICs) only transmit voltage signals, so the pixel driving Circuit of the AMOLED needs to complete the task of converting the voltage signals into current signals. A conventional AMOLED pixel driving circuit is typically 2T1C, i.e. two thin film transistors plus a capacitor to convert a voltage into a current.
As shown in fig. 1, the conventional 2T1C pixel driving circuit for an AMOLED includes a first thin film transistor T10, a second thin film transistor T20, and a capacitor C, wherein the first thin film transistor T10 is a switching thin film transistor, the second thin film transistor T20 is a driving thin film transistor, and the capacitor C is a storage capacitor. Specifically, the gate of the first thin film transistor T10 is electrically connected to the Scan signal Scan, the source is electrically connected to the Data voltage Data, and the drain is electrically connected to the gate of the second thin film transistor T20 and one end of the capacitor C; the source electrode of the second thin film transistor T20 is electrically connected to the positive power voltage VDD0, and the drain electrode is electrically connected to the anode of the organic light emitting diode D0; the cathode of the organic light emitting diode D0 is electrically connected to the ground voltage GND 0; one end of the capacitor C is electrically connected to the drain of the first thin film transistor T10, and the other end is connected to the ground voltage GND 0. When the AMOLED displays, the Scan signal Scan controls the first thin film transistor T10 to be turned on, the Data voltage Data enters the gate of the second thin film transistor T20 and the capacitor C through the first thin film transistor T10, and then the first thin film transistor T10 is turned on, due to the storage effect of the capacitor C, the gate voltage of the second thin film transistor T20 can still keep the Data voltage, so that the second thin film transistor T20 is in a conducting state, and the driving current enters the organic light emitting diode D0 through the second thin film transistor T20 to drive the organic light emitting diode D0 to emit light.
The 2T1C pixel driving circuit for AMOLED of the conventional circuit described above is very sensitive to variations in threshold voltage and mobility of the thin film transistor. The threshold voltage and mobility of the second thin film transistor T20, i.e., the driving thin film transistor, may change with the operation time, thereby causing unstable light emission of the organic light emitting diode D0; further, the second thin film transistor T20 of each pixel, i.e., the driving thin film transistor, has a shift in threshold voltage and a change in mobility, which results in uneven light emission and brightness among the pixels. The non-uniformity of the AMOLED display brightness caused by using such a conventional 2T1C pixel drive circuit without compensation is about 50% or even higher.
Therefore, a new AMOLED pixel driving circuit is needed to solve the problem of non-uniform display brightness of the AMOLED.
Disclosure of Invention
In view of the above, an objective of the present invention is to provide an AMOLED pixel driving circuit and driving method, in which a compensation circuit is added to each pixel, that is, the threshold voltage and mobility of the driving thin film transistor in each pixel are compensated, so that the output current becomes independent of these parameters, thereby solving the problem of non-uniform display brightness of the AMOLED.
In order to achieve the purpose, the invention provides the following technical scheme:
an AMOLED pixel drive circuit, comprising: a first thin film transistor T1, a second thin film transistor T2, a third thin film transistor T3, a fourth thin film transistor T4, a fifth thin film transistor T5, a sixth thin film transistor T6, a first capacitor C1, a second capacitor C2, and an organic light emitting diode OLED;
the gate of the first thin film transistor T1 is connected to a first scan control signal VSCAN1, the source is electrically connected to the node a, and the drain is connected to an initialization driving voltage VCOMP;
the gate of the second thin film transistor T2 is connected to the second scan control signal VSCAN2, the drain is electrically connected to the node a, and the source is electrically connected to the source of the third thin film transistor T3;
the gate of the third thin film transistor T3 is connected to the third scan control signal VSCAN3, the drain is electrically connected to the cathode of the organic light emitting diode OLED, and the source is electrically connected to the source of the second thin film transistor T2;
the gate of the fourth thin film transistor T4 is connected to the fourth scan control signal VSCAN4, the drain is electrically connected to the source of the fifth thin film transistor T5, and the source is connected to one end of the second capacitor C2;
the gate of the fifth thin film transistor T5 is electrically connected to the node a, the drain is electrically connected to the source of the third thin film transistor T3, and the source is electrically connected to the drain of the fourth thin film transistor T4;
the gate of the sixth thin film transistor T6 is connected to the high voltage VDD, the drain is electrically connected to the drain of the fourth thin film transistor T4, and the source is connected to the data voltage VDATA;
one end of the first capacitor C1 is electrically connected to the node A, and the other end is connected to a ground voltage GND;
one end of the second capacitor C2 is electrically connected to the source of the fourth tft T4, and the other end is electrically connected to the node a;
and the anode of the organic light emitting diode OLED is connected with a power supply high voltage VDD.
Preferably, the first, second, third, fourth, fifth and sixth thin film transistors T1, T2, T3, T4, T5 and T6 are all low temperature polysilicon thin film transistors, oxide semiconductor thin film transistors, amorphous silicon thin film transistors or organic thin film transistors.
Preferably, the first, second, third and fourth scan control signals VSCAN1, VSCAN2, VSCAN3 and VSCAN4, the initialization driving voltage VCOMP and the data voltage VDATA are all provided by an external timing controller.
Preferably, the driving sequence of the AMOLED pixel driving circuit sequentially includes:
(1) an initialization stage: the first scan control signal VSCAN1 and the initialization driving voltage VCOMP provide a high potential, and the second scan control signal VSCAN2, the third scan control signal VSCAN3, and the fourth scan control signal VSCAN4 all provide a low potential;
(2) a data voltage input stage: the first scan control signal VSCAN1, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4, and the initialization driving voltage VCOMP provide a low potential, and the second scan control signal VSCAN2 provides a high potential;
the data voltage input stage completes the input of the data voltage and the compensation of the threshold voltage of the fifth thin film transistor T5 at the same time;
(3) a light emitting stage: the first scan control signal VSCAN1, the second scan control signal VSCAN2, and the initialization driving voltage VCOMP provide low potentials, and the third scan control signal VSCAN3 and the fourth scan control signal VSCAN4 provide high potentials;
the light emitting stage simultaneously performs light emission of the organic light emitting diode and compensation of the mobility of the fifth thin film transistor T5.
Further, the pixel driving method of the AMOLED pixel driving circuit specifically includes the following steps:
s1: entering an initialization stage;
the first scan control signal VSCAN1 and the initialization driving voltage VCOMP provide a high potential, and the second scan control signal VSCAN2, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4 and the data voltage VDATA provide a low potential of 0V; the first thin film transistor and the sixth thin film transistor (T1, T6) are turned on, the second thin film transistor, the third thin film transistor, the fourth thin film transistor and the fifth thin film transistor (T2, T3, T4 and T5) are turned off, the gate of the fifth thin film transistor T5 is shorted with the high level of the initialization driving voltage VCOMP, at this time, the gate voltage VG _ T5 of the fifth thin film transistor is initialized to VCOMP _ H, and the VCOMP _ H is the high level provided by the initialization driving voltage VCOMP;
s2: entering a data voltage input stage;
the first scan control signal VSCAN1, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4, and the initialization driving voltage VCOMP provide a low potential, and the second scan control signal VSCAN2, and the data voltage VDATA provide a high potential; the second thin film transistor, the fifth thin film transistor and the sixth thin film transistor (T2, T5, T6) are turned on, the first thin film transistor, the third thin film transistor, the fourth thin film transistor T1, T3 and T4 are turned off, the fifth thin film transistor T5 is in a diode connection state, at this time, the gate voltage VG _ T5 of the fifth thin film transistor is discharged to VDATA _ H + Vth _ T5 through the second thin film transistor T2, the fifth thin film transistor T5 and the sixth thin film transistor T6, wherein VDATA _ H is a high potential of the data voltage VDATA, and Vth _ T5 is a threshold voltage of the fifth thin film transistor T5;
s3: entering a light emitting stage;
the first scan control signal VSCAN1, the second scan control signal VSCAN2, the initialization driving voltage VCOMP providing a low potential, the data voltage VDATA providing a low potential of 0V, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4 providing a high potential; the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor, the sixth thin film transistor T3, T4, T5 and T6 are turned on, and the first thin film transistor, the second thin film transistor T1 and T2 are turned off; the first capacitor C1 and the second capacitor C2 are connected in parallel, a gate voltage VG _ T5 of the fifth tft T5 is equal to VDATA _ H + Vth _ T5+ (C2/C1+ C2) VGs _ T6, where C1 is a capacitance value of the first capacitor C1, C2 is a capacitance value of the second capacitor C2, VDATA _ H is a high potential of a data voltage VDATA, Vth _ T5 is a threshold voltage of the fifth tft T5, and VGs _ T6 is a difference between voltages of the gate and the source of the sixth tft T6; the current flowing through the organic light emitting diode OLED is made independent of the threshold voltage Vth _ T5 of the fifth thin film transistor T5 while suppressing the influence of the mobility variation of the fifth thin film transistor T5 on the current flowing through the light emitting diode OLED.
The invention has the beneficial effects that: the invention can effectively compensate the threshold voltage and the mobility of the driving film, stabilize the current flowing through the organic light-emitting diode, ensure the uniform brightness of the organic light-emitting diode and improve the display effect of the picture.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
fig. 1 is a circuit diagram of a conventional 2T1C pixel driving circuit for an AMOLED;
FIG. 2 is a circuit diagram of a 6T2C pixel driving circuit for AMOLED according to the present invention;
FIG. 3 is a timing diagram of the 6T2C pixel driving circuit for AMOLED according to the present invention;
FIG. 4 is a schematic diagram of an initialization stage in the AMOLED pixel driving method according to the present invention;
FIG. 5 is a schematic diagram of a data voltage input stage in the AMOLED pixel driving method according to the present invention;
fig. 6 is a schematic diagram of a light emitting stage in the AMOLED pixel driving method according to the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Referring to fig. 2 to 6, the present invention provides an AMOLED pixel driving circuit, including: the organic light emitting diode includes a first thin film transistor T1, a second thin film transistor T2, a third thin film transistor T3, a fourth thin film transistor T4, a fifth thin film transistor T5, a sixth thin film transistor T6, a first capacitor C1, a second capacitor C2, and an organic light emitting diode OLED.
The concrete connection mode is as follows: the gate of the first thin film transistor T1 is connected to the first scan control signal VSCAN1, the source is electrically connected to the node a, and the drain is connected to the initialization driving voltage VCOMP; the gate of the second thin film transistor T2 is connected to the second scan control signal VSCAN2, the drain is electrically connected to the node a, and the source is electrically connected to the source of the third thin film transistor T3; a gate of the third thin film transistor T3 is connected to the third scan control signal VSCAN3, a drain thereof is electrically connected to the cathode of the organic light emitting diode OLED, and a source thereof is electrically connected to the source of the second thin film transistor T2; the gate of the fourth thin film transistor T4 is connected to the fourth scan control signal VSCAN4, the drain is electrically connected to the source of the fifth thin film transistor T5, and the source is connected to one end of the second capacitor C2; the gate of the fifth thin film transistor T5 is electrically connected to the node a, the drain is electrically connected to the source of the third thin film transistor T3, and the source is electrically connected to the drain of the fourth thin film transistor T4; a grid electrode of the sixth thin film transistor T6 is connected to the power supply high voltage VDD, a drain electrode is electrically connected to a drain electrode of the fourth thin film transistor T4, and a source electrode is connected to the data voltage VDATA; one end of the first capacitor C1 is electrically connected to the node a, and the other end is connected to the ground voltage GND; one end of the second capacitor C2 is electrically connected to the source of the fourth tft T4, and the other end is electrically connected to the node a; the anode of the organic light emitting diode OLED is connected with a power supply high voltage VDD.
Preferably, the fifth thin film transistor T5 is a driving thin film transistor for driving the organic light emitting diode OLED to emit light, and the AMOLED pixel driving circuit is capable of compensating for a threshold voltage of the driving thin film transistor, i.e., the first thin film transistor T1.
Preferably, the first, second, third, fourth, fifth and sixth thin film transistors T1, T2, T3, T4, T5 and T6 are all low temperature polysilicon thin film transistors, oxide semiconductor thin film transistors, amorphous silicon thin film transistors or organic thin film transistors.
Preferably, the scan control signals VSCAN1, VSCAN2, VSCAN3, VSCAN4, the initialization driving voltage VCOMP, and the data voltage VDATA are all provided through an external timing controller.
As shown in fig. 3, the first scan control signal VSCAN1, the second scan control signal VSCAN2, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4, the initialization drive voltage VCOMP, and the data voltage VDATA are combined to correspond to the initialization stage (1), the data voltage input stage (2), and the light emitting stage (3) in sequence;
in the initialization stage (1), the first scan control signal VSCAN1 and the initialization driving voltage VCOMP provide a high potential, and the second scan control signal VSCAN2, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4 and the data voltage VDATA provide a low potential of 0V; the first thin film transistor T1 and the sixth thin film transistor T6 are turned on, the second thin film transistor T2, the third thin film transistor T3, the fourth thin film transistor T4 and the fifth thin film transistor T5 are turned off, and the gate of the fifth thin film transistor T5 is shorted with the high level of the initialization driving voltage VCOMP, at which time the gate voltage VG _ T5 of the fifth thin film transistor is initialized to VCOMP _ H, which is the high level provided by the initialization driving voltage VCOMP.
In the data voltage input stage (2), the first scan control signal VSCAN1, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4, and the initialization driving voltage VCOMP provide a low potential, and the second scan control signal VSCAN2, and the data voltage VDATA provide a high potential; the second thin film transistor, the fifth thin film transistor, the sixth thin film transistor T2, T5, and T6 are turned on, the first thin film transistor, the third thin film transistor, the fourth thin film transistor T1, T3, and T4 are turned off, and the fifth thin film transistor T5 is in a diode connection state, at this time, the fifth thin film transistor gate voltage VG _ T5 is discharged to VDATA _ H + Vth _ T5 through the second thin film transistor T2, the fifth thin film transistor T5, and the sixth thin film transistor T6, where VDATA _ H is a high potential of the data voltage VDATA, and Vth _ T5 is a threshold voltage of the fifth thin film transistor T5.
In the light emitting period (3), the first scan control signal VSCAN1, the second scan control signal VSCAN2, the initialization driving voltage VCOMP are supplied with the low potential, the data voltage VDATA is supplied with the low potential 0V, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4 are supplied with the high potential; the third thin film transistor T3, the fourth thin film transistor T4, the fifth thin film transistor T5, and the sixth thin film transistor T6 are turned on, and the first thin film transistor T1 and the second thin film transistor T2 are turned off; the first capacitor C1 and the second capacitor C2 are connected in parallel, the gate voltage VG _ T5 of the fifth tft T5 is equal to VDATA _ H + Vth _ T5+ (C1/C1+ C2) VGs _ T6, where C1 is the capacitance value of the first capacitor C1, C2 is the capacitance value of the second capacitor C2, VDATA _ H is the high potential of the data voltage VDATA, Vth _ T5 is the threshold voltage of the fifth tft T5, and VGs _ T6 is the difference between the voltages of the gate and the source of the sixth tft T6; the current flowing through the organic light emitting diode OLED is made independent of the threshold voltage Vth _ T5 of the fifth thin film transistor T5 while suppressing the influence of the mobility variation of the fifth thin film transistor T5 on the current flowing through the light emitting diode OLED.
The pixel driving method of the AMOLED pixel driving circuit designed in this embodiment specifically includes the following steps:
step 1, providing an AMOLED pixel driving circuit with a 6T2C structure as shown in fig. 2;
step 2, entering an initialization stage:
referring to fig. 3 and 4, the first scan control signal VSCAN1 and the initialization driving voltage VCOMP provide a high voltage, and the second scan control signal VSCAN2, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4, and the data voltage VDATA provide a low voltage of 0V; the first thin film transistor T1 and the sixth thin film transistor T6 are turned on, the second thin film transistor T2, the third thin film transistor T3, the fourth thin film transistor T4 and the fifth thin film transistor T5 are turned off, the gate of the fifth thin film transistor T5 is shorted with the high level of the initialization driving voltage VCOMP, at this time, the gate voltage VG _ T5 of the fifth thin film transistor is initialized to VCOMP _ H, which is the high level provided by the initialization driving voltage VCOMP, and the organic light emitting diode OLED does not emit light.
And step 3, entering a data voltage input stage:
referring to fig. 3 and 5, the first scan control signal VSCAN1, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4, the initialization driving voltage VCOMP provide a low potential, and the second scan control signal VSCAN2, the data voltage VDATA provide a high potential; the second thin film transistor T2, the fifth thin film transistor T5, and the sixth thin film transistor T6 are turned on, the first thin film transistor T1, the third thin film transistor T3, and the fourth thin film transistor T4 are turned off, and the fifth thin film transistor T5 is in a diode connection state, at this time, the fifth thin film transistor gate voltage VG _ T5 is discharged to VDATA _ H + Vth _ T5 through the second thin film transistor T2, the fifth thin film transistor T5, and the sixth thin film transistor T6, where VDATA _ H is a high potential of the data voltage VDATA, Vth _ T5 is a threshold voltage of the fifth thin film transistor T5, and the organic light emitting diode OLED does not emit light.
And 4, entering a light-emitting stage:
referring to fig. 3 and 6, the first scan control signal VSCAN1, the second scan control signal VSCAN2, the initialization driving voltage VCOMP are supplied with a low potential, the data voltage VDATA is supplied with a low potential of 0V, the third scan control signal VSCAN3, the fourth scan control signal VSCAN4 are supplied with a high potential; the third thin film transistor T3, the fourth thin film transistor T4, the fifth thin film transistor T5, and the sixth thin film transistor T6 are turned on, and the first thin film transistor T1 and the second thin film transistor T2 are turned off; the first capacitor C1 and the second capacitor C2 are connected in parallel, and the gate voltage VG _ T5 of the fifth thin film transistor T5 isAt VDATA _ H + Vth _ T5+ (C2/C1+ C2) VGS _ T6, wherein C1 is the capacitance of the first capacitor, C2 is the capacitance of the second capacitor, VDATA _ H is the high potential V of the data voltage VDATAth_T5VGS _ T6 is a difference between voltages of the gate and the source of the sixth thin film transistor T6, which is a threshold voltage of the fifth thin film transistor T5; the current flowing through the organic light emitting diode OLED is made independent of the threshold voltage Vth _ T5 of the fifth thin film transistor T5 while suppressing the influence of the mobility variation of the fifth thin film transistor T5 on the current flowing through the light emitting diode OLED.
It should be noted that, when the thin film transistor is adopted as the driving thin film transistor according to the prior art, the current formula flowing through the organic light emitting diode is as follows:
IOLED＝K(VGS_T5-Vth_T5)2
here, the IOLED is a current flowing through the organic light emitting diode OLED, K is a structural parameter of the driving thin film transistor, that is, the fifth thin film transistor T5, VGS _ T5 is a voltage difference between a gate and a source of the driving thin film transistor, that is, the fifth thin film transistor T5, Vth _ T5 is a threshold voltage of the fifth thin film transistor T5, and a voltage difference between the gate and the source of the fifth thin film transistor T5 at this time is: VDATA _ H + Vth _ T5+ (C2/C1+ C1) VGS _ T6-VGS _ T6.
Thus, IOLED is K (VGS _ T5-Vth _ T5)2＝K(VDATA_H-(C1/C1+C2)VGS_T6)2Wherein C1 is the capacitance of the first capacitor, C2 is the capacitance of the second capacitor, VDATA _ H is the high level of the data voltage VDATA, VGS _ T6 is the voltage difference between the gate and the source of the sixth TFT T6, for the thin film transistor with the same structure, the K value is relatively stable, the value of (C1/C1+ C2) VGS _ T6 is also relatively stable, so that the current flowing through the organic light emitting diode OLED is independent of the threshold voltage of the fifth thin film transistor T5, (C1/C1+ C2) VGS _ T6 can suppress the influence of the mobility change of the fifth thin film transistor on the current flowing through the organic light emitting diode, therefore, the threshold voltage and the mobility of the driving thin film transistor T5 can be effectively compensated, the stability of the current flowing through the organic light emitting diode OLED is ensured, the brightness uniformity of the organic light emitting diode is ensured, and the display quality of the organic light emitting diode is improved.
In summary, the AMOLED pixel driving circuit provided by the invention adopts the pixel driving circuit with the 6T2C structure and is matched with a specific driving timing sequence, and performs threshold voltage compensation by directly capturing the threshold voltage of the fifth thin film transistor, i.e., the driving thin film transistor; applying a part of the drain voltage of the sixth thin film transistor to the node A through the parallel connection of the second capacitor and the first capacitor for mobility compensation; the current flowing through the organic light-emitting diode is stable by compensating the threshold voltage and the mobility of the driving thin film transistor, so that the light-emitting brightness of the organic light-emitting diode is ensured; the data voltage is input from the source electrode of the sixth thin film transistor, so that the circuit reads the data voltage while grabbing the driving thin film transistor, and grabbing of the threshold voltage and reading of the data voltage are combined into a whole, so that the working stage of the circuit is reduced, and the efficiency is improved; the organic light emitting diode is controlled by the signal to have current passing only in the light emitting stage, so that unnecessary light emission of the organic light emitting diode is avoided, the display quality of the organic light emitting diode is improved, and the power consumption is reduced.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims (5)

1. An AMOLED pixel driving circuit, comprising: a first thin film transistor (T1), a second thin film transistor (T2), a third thin film transistor (T3), a fourth thin film transistor (T4), a fifth thin film transistor (T5), a sixth thin film transistor (T6), a first capacitor (C1), a second capacitor (C2), and an Organic Light Emitting Diode (OLED);
the grid of the first thin film transistor (T1) is connected to a first scanning control signal (VSCAN1), the source is electrically connected to the node (A), and the drain is connected to an initialization driving Voltage (VCOMP);
the grid electrode of the second thin film transistor (T2) is connected to a second scanning control signal (VSCAN2), the drain electrode of the second thin film transistor is electrically connected to the node (A), and the source electrode of the second thin film transistor is electrically connected to the source electrode of the third thin film transistor (T3);
the grid electrode of the third thin film transistor (T3) is connected to a third scanning control signal (VSCAN3), the drain electrode of the third thin film transistor is electrically connected to the cathode of the Organic Light Emitting Diode (OLED), and the source electrode of the third thin film transistor is electrically connected to the source electrode of the second thin film transistor (T2);
the grid electrode of the fourth thin film transistor (T4) is connected to a fourth scanning control signal (VSCAN4), the drain electrode of the fourth thin film transistor is electrically connected to the source electrode of the fifth thin film transistor (T5), and the source electrode of the fourth thin film transistor is connected to one end of the second capacitor (C2);
the gate of the fifth thin film transistor (T5) is electrically connected to the node (a), the drain is electrically connected to the source of the third thin film transistor (T3), and the source is electrically connected to the drain of the fourth thin film transistor (T4);
the grid electrode of the sixth thin film transistor (T6) is connected with a power supply high Voltage (VDD), the drain electrode of the sixth thin film transistor is electrically connected with the drain electrode of the fourth thin film transistor (T4), and the source electrode of the sixth thin film transistor is connected with a data Voltage (VDATA);
one end of the first capacitor (C1) is electrically connected to the node (A), and the other end of the first capacitor is connected to the ground voltage (GND);
one end of the second capacitor (C2) is electrically connected to the source of the fourth thin film transistor (T4), and the other end of the second capacitor (C2) is electrically connected to the node (A);
the anode of the Organic Light Emitting Diode (OLED) is connected with a power supply high Voltage (VDD).
2. The AMOLED pixel driving circuit as claimed in claim 1, wherein the first, second, third, fourth, fifth and sixth thin film transistors (T1, T2, T3, T4, T5 and T6) are all low temperature polysilicon thin film transistors, oxide semiconductor thin film transistors, amorphous silicon thin film transistors or organic thin film transistors.
3. The AMOLED pixel driving circuit as claimed in claim 1, wherein the first, second, third and fourth scan control signals (VSCAN1, VSCAN2, VSCAN3 and VSCAN4), the initialization driving Voltage (VCOMP) and the data Voltage (VDATA) are all provided through an external timing controller.
4. The AMOLED pixel drive circuit of claim 1, wherein a drive timing sequence of the AMOLED pixel drive circuit sequentially comprises:
(1) an initialization stage: the first scan control signal (VSCAN1) and the initialization driving Voltage (VCOMP) provide a high potential, and the second scan control signal (VSCAN2), the third scan control signal (VSCAN3), and the fourth scan control signal (VSCAN4) all provide a low potential;
(2) a data voltage input stage: the first scanning control signal (VSCAN1), the third scanning control signal (VSCAN3), the fourth scanning control signal (VSCAN4), the initialization driving Voltage (VCOMP) provide low potential, and the second scanning control signal (VSCAN2) provides high potential;
(3) a light emitting stage: the first scan control signal (VSCAN1), the second scan control signal (VSCAN2), and the initialization drive Voltage (VCOMP) are supplied with low potentials, and the third scan control signal (VSCAN3) and the fourth scan control signal (VSCAN4) are supplied with high potentials.
5. An AMOLED pixel driving method applicable to the AMOLED pixel driving circuit of claim 1, comprising:
s1: entering an initialization stage;
the first scan control signal (VSCAN1) and the initialization driving Voltage (VCOMP) provide a high potential, and the second scan control signal (VSCAN2), the third scan control signal (VSCAN3), the fourth scan control signal (VSCAN4), the data Voltage (VDATA) provide a low potential of 0V; the first thin film transistor, the sixth thin film transistor (T1, T6) are turned on, the second thin film transistor, the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor (T2, T3, T4, T5) are turned off, the gate of the fifth thin film transistor (T5) is shorted with the high level of the initialization driving Voltage (VCOMP), and the gate voltage (VG _ T5) of the fifth thin film transistor is initialized to VCOMP _ H, wherein VCOMP _ H is the high level provided by the initialization driving Voltage (VCOMP);
s2: entering a data voltage input stage;
the first scan control signal (VSCAN1), the third scan control signal (VSCAN3), the fourth scan control signal (VSCAN4), the initialization drive Voltage (VCOMP) provide a low potential, the second scan control signal (VSCAN2), the data Voltage (VDATA) provide a high potential; the second thin film transistor, the fifth thin film transistor and the sixth thin film transistor (T2, T5, T6) are turned on, the first thin film transistor, the third thin film transistor and the fourth thin film transistor (T1, T3, T4) are turned off, the fifth thin film transistor (T5) is in a diode connection state, at this time, a gate voltage (VG _ T5) of the fifth thin film transistor is discharged to VDATA _ H + Vth _ T5 through the second thin film transistor (T2), the fifth thin film transistor (T5) and the sixth thin film transistor (T6), wherein VDATA _ H is a high potential of a data Voltage (VDATA), and Vth _ T5 is a threshold voltage of the fifth thin film transistor (T5);
s3: entering a light emitting stage;
the first scanning control signal (VSCAN1), the second scanning control signal (VSCAN)2) The initialization driving Voltage (VCOMP) provides a low potential, the data Voltage (VDATA) provides a low potential (0V), the third scan control signal (VSCAN3), the fourth scan control signal (VSCAN4) provides a high potential; the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor and the sixth thin film transistor (T3, T4, T5 and T6) are turned on, and the first thin film transistor and the second thin film transistor (T1 and T2) are turned off; the first capacitor (C1) and the second capacitor (C2) are connected in parallel, and the gate voltage (VG _ T5) of the fifth thin film transistor (T5) is equal to VDATA _ H + Vth _ T5+ (C2/C1+ C2) VGs _ T6, where C1 is the capacitance value of the first capacitor (C1), C2 is the capacitance value of the second capacitor (C2), VDATA _ H is the high potential of the data Voltage (VDATA), Vth _ T5 is the threshold voltage of the fifth thin film transistor (T5), and VGs _ T6 is the difference between the gate and source voltages of the sixth thin film transistor (T6).
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