CN107180612B - A kind of pixel circuit and display panel - Google Patents
A kind of pixel circuit and display panel Download PDFInfo
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- CN107180612B CN107180612B CN201710606743.7A CN201710606743A CN107180612B CN 107180612 B CN107180612 B CN 107180612B CN 201710606743 A CN201710606743 A CN 201710606743A CN 107180612 B CN107180612 B CN 107180612B
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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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Abstract
The invention discloses a kind of pixel circuit and display panels, in reseting stage, compensated stage and light emitting phase, reseting module, drive module, switch module, control module, writing module, compensating module in pixel circuit complete corresponding function under the control of respective control terminal, so as to realize that normal driving luminescent device shines；The first input end of compensating module or the voltage signal of third node are adjusted by adjustment module simultaneously, and then compensating module adjusts the voltage of the control terminal of drive module according to the voltage signal of first input end or third node, reduce or eliminate the case where driving current that drive module is increased with temperature and exported increases, so as to improve the colour cast problem of display panel caused by high temperature, achieve the purpose that display panel white balance at different temperatures.
Description
Technical Field
The invention relates to the technical field of display, in particular to a pixel circuit and a display panel.
Background
In recent years, with the rapid development of display technology, Organic Light Emitting Displays (OLEDs) become one of the hot spots in the research field of flat panel displays, and more Active Matrix Organic Light Emitting Diode (AMOLED) display panels enter the market. Compared with a traditional Thin Film Transistor Liquid Crystal Display (TFTLCD), the AMOLED Display has the advantages of wide color gamut, high response speed, wide viewing angle, foldability and the like.
However, after the AMOLED display is tested for high temperature reliability, it is found that as the temperature increases, the mobility of the driving transistor driving the OLED to emit light also increases, which increases the driving current flowing through the OLED, thereby increasing the brightness of RGB single color, and causing color shift due to different increasing ratios of RGB brightness. As shown in the following table, the test results obtained after the OLED display panel is subjected to a high-temperature reliability test show that when the display panel is placed in a temperature environment of 70 ℃ from room temperature, the brightness of white light of the display panel increases, and the color coordinates shift to the yellow direction; when the display panel is returned to room temperature, the brightness and color coordinates of the white light are returned to the original level.
Therefore, how to improve the problem of color shift of the display panel caused by high temperature is a technical problem to be solved urgently by those skilled in the art.
Disclosure of Invention
The embodiment of the invention provides a pixel circuit and a display panel, which are used for solving the problem of color cast of the display panel caused by high temperature in the prior art.
An embodiment of the present invention provides a pixel circuit, including: the device comprises a reset module, a driving module, a switch module, a control module, a writing module, a compensation module, an adjusting module and a light-emitting device; wherein,
the control end of the reset module is connected with the reset signal end, the input end of the reset module is used for inputting an initialization signal, and the output end of the reset module is connected with the first node;
the control end of the driving module is connected with the first node, the input end of the driving module is used for inputting a power supply signal, and the output end of the driving module is connected with the second node;
the control end of the switch module is used for inputting a light-emitting control signal, the input end of the switch module is connected with the second node, and the output end of the switch module is connected with the input end of the light-emitting device; the output end of the light-emitting device is used for accessing a low level signal;
the first control end of the control module is connected with the reset signal end, the second control end is used for inputting the light-emitting control signal, the input end is used for inputting a reference signal, and the output end is electrically connected with the third node;
the control end of the writing module is used for inputting scanning signals, the input end of the writing module is used for inputting data signals, and the output end of the writing module is electrically connected with the third node;
the control end of the compensation module is used for inputting the scanning signal, the first input end is electrically connected with the second node, the second input end is connected with the third node, and the output end is connected with the first node;
the adjusting module is connected between the first input end of the compensating module and the second node; or between the output end of the control module and the third node; or between the output end of the writing module and the third node; wherein the pressure differential across the conditioning module decreases with increasing temperature;
in a reset phase, the reset module is configured to output the initialization signal to the first node under the control of the reset signal terminal; the control module is used for outputting the reference signal to the third node under the control of the reset signal end;
in a compensation phase, the write module is configured to output the data signal to the third node under the control of the scan signal; the adjusting module is used for adjusting a voltage signal of a first input end of the compensating module according to a voltage signal of the second node, or adjusting a voltage signal of a third node according to a voltage signal of an output end of the control module, or adjusting a voltage signal of the third node according to a voltage signal of an output end of the writing module; the compensation module is used for compensating the threshold voltage of the driving module for the first node under the control of the scanning signal;
in a light emitting phase, the control module is configured to output the reference signal to the third node under the control of the light emitting control signal; the compensation module is used for adjusting the potential of the first node according to the potential of the third node; the driving module is used for outputting the power supply signal to the second node under the control of the first node; the switch module is used for conducting the second node and the input end of the light-emitting device under the control of the light-emitting control signal to drive the light-emitting device to emit light.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the driving module includes: a first switching transistor;
and the grid electrode of the first switch transistor is connected with the first node, the source electrode of the first switch transistor is used for inputting the power supply signal, and the drain electrode of the first switch transistor is connected with the second node.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the reset module includes: a second switching transistor;
and the grid electrode of the second switching transistor is connected with the reset signal end, the source electrode of the second switching transistor is used for inputting the initialization signal, and the drain electrode of the second switching transistor is connected with the first node.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the switch module includes: a third switching transistor;
and the grid electrode of the third switching transistor is used for inputting the light-emitting control signal, the source electrode of the third switching transistor is connected with the second node, and the drain electrode of the third switching transistor is connected with the input end of the light-emitting device.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the control module includes: a fourth switching transistor and a fifth switching transistor; wherein,
the grid electrode of the fourth switching transistor is connected with the reset signal end, the source electrode of the fourth switching transistor is used for inputting the reference signal, and the drain electrode of the fourth switching transistor is electrically connected with the third node;
the gate of the fifth switching transistor is used for inputting the light-emitting control signal, the source of the fifth switching transistor is used for inputting the reference signal, and the drain of the fifth switching transistor is electrically connected with the third node.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the writing module includes: a sixth switching transistor;
and the grid electrode of the sixth switching transistor is used for inputting the scanning signal, the source electrode of the sixth switching transistor is used for inputting the data signal, and the drain electrode of the sixth switching transistor is electrically connected with the third node.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the compensation module includes: a seventh switching transistor and a capacitor; wherein,
the grid electrode of the seventh switching transistor is used for inputting the scanning signal, the source electrode of the seventh switching transistor is electrically connected with the second node, and the drain electrode of the seventh switching transistor is connected with the first node;
the capacitor is connected between the first node and the third node.
In a possible implementation manner, in the pixel circuit provided in an embodiment of the present invention, the adjusting module includes: a diode;
the diode is connected between the first input end of the compensation module and the second node; or between the output end of the control module and the third node; or between the output of the write module and the third node.
The embodiment of the invention provides a display panel, which comprises the pixel circuit provided by the embodiment of the invention.
The embodiment of the invention has the beneficial effects that:
the embodiment of the invention provides a pixel circuit and a display panel, wherein the pixel circuit comprises: the device comprises a reset module, a driving module, a switch module, a control module, a writing module, a compensation module, an adjusting module and a light-emitting device; the control end of the reset module is connected with the reset signal end, the input end of the reset module is used for inputting an initialization signal, and the output end of the reset module is connected with the first node; the control end of the driving module is connected with the first node, the input end of the driving module is used for inputting a power supply signal, and the output end of the driving module is connected with the second node; the control end of the switch module is used for inputting a light-emitting control signal, the input end of the switch module is connected with the second node, and the output end of the switch module is connected with the input end of the light-emitting device; the output end of the light-emitting device is used for accessing a low level signal; the first control end of the control module is connected with the reset signal end, the second control end is used for inputting a light-emitting control signal, the input end is used for inputting a reference signal, and the output end is electrically connected with the third node; the control end of the writing module is used for inputting scanning signals, the input end of the writing module is used for inputting data signals, and the output end of the writing module is electrically connected with the third node; the control end of the compensation module is used for inputting scanning signals, the first input end is electrically connected with the second node, the second input end is connected with the third node, and the output end is connected with the first node; the adjusting module is connected between the first input end and the second node of the compensating module; or between the output end of the control module and the third node; or the output end of the writing module is connected with the third node; wherein the pressure difference across the conditioning module decreases with increasing temperature;
in the reset stage, the reset module is used for outputting an initialization signal to the first node under the control of the reset signal end; the control module is used for outputting a reference signal to a third node under the control of the reset signal end;
in the compensation stage, the write-in module is used for outputting the data signal to a third node under the control of the scanning signal; the adjusting module is used for adjusting a voltage signal of a first input end of the compensating module according to a voltage signal of a second node, or adjusting a voltage signal of a third node according to a voltage signal of an output end of the control module, or adjusting a voltage signal of the third node according to a voltage signal of an output end of the writing module; the compensation module is used for compensating the threshold voltage of the driving module for the first node under the control of the scanning signal;
in the light emitting stage, the control module is used for outputting the reference signal to the third node under the control of the light emitting control signal; the compensation module is used for adjusting the potential of the first node according to the potential of the third node; the driving module is used for outputting a power supply signal to the second node under the control of the first node; the switch module is used for conducting the second node and the input end of the light-emitting device under the control of the light-emitting control signal to drive the light-emitting device to emit light.
Specifically, in the pixel circuit provided in the embodiment of the present invention, in the reset stage, the compensation stage, and the light emitting stage, the reset module, the driving module, the switch module, the control module, the write-in module, and the compensation module in the pixel circuit complete corresponding functions under the control of their respective control terminals, so as to realize normal driving of the light emitting device to emit light; meanwhile, the voltage signal of the first input end or the third node of the compensation module is adjusted through the adjusting module, the compensation module adjusts the voltage of the control end of the driving module according to the voltage signal of the first input end or the third node, and the condition that the driving current output by the driving module increases along with the rise of the temperature is reduced or eliminated, so that the problem of color cast of the display panel caused by high temperature is solved, and the purpose of white balance of the display panel at different temperatures is achieved.
Drawings
Fig. 1a to fig. 1c are schematic structural diagrams of a pixel circuit according to an embodiment of the invention;
fig. 2a to fig. 2c are schematic structural diagrams of a pixel circuit according to an embodiment of the invention;
FIG. 3 is a schematic diagram of the energy levels of a diode according to an embodiment of the present invention;
fig. 4 is a timing diagram of the operation of the pixel circuit according to the embodiment of the invention.
Detailed Description
The following describes in detail specific embodiments of a pixel circuit and a display panel according to an embodiment of the present invention with reference to the drawings.
An embodiment of the present invention provides a pixel circuit, as shown in fig. 1a to 1c, which may include: the device comprises a reset module 01, a driving module 02, a switch module 03, a control module 04, a writing module 05, a compensation module 06, an adjusting module 07 and a light-emitting device OLED; wherein,
the control end of the Reset module 01 is connected with a Reset signal end Reset, the input end is used for inputting an initialization signal Vinit, and the output end is connected with a first node P1;
the control end of the driving module 02 is connected with the first node P1, the input end is used for inputting a power supply signal Vdd, and the output end is connected with the second node P2;
the control end of the switch module 03 is used for inputting a light-emitting control signal EM, the input end is connected with the second node P2, and the output end is connected with the input end of the light-emitting device OLED; the output end of the light-emitting device OLED is used for accessing a low level signal Vss;
a first control end of the control module 04 is connected with a Reset signal end Reset, a second control end is used for inputting a light-emitting control signal EM, an input end is used for inputting a reference signal Vref, and an output end is electrically connected with a third node P3;
the control end of the write-in module 05 is used for inputting a scanning signal Gate, the input end is used for inputting a data signal Vdata, and the output end is electrically connected with the third node P3;
the control end of the compensation module 06 is used for inputting a scan signal Gate, the first input end is electrically connected to the second node P2, the second input end is connected to the third node P3, and the output end is connected to the first node P1;
the regulation module 07 is connected between the first input of the compensation module 06 and the second node P2, as shown in fig. 1 a; or between the output of the control module 04 and the third node P3, as shown in fig. 1 b; or between the output of the write module 05 and the third node P3, as shown in fig. 1 c; wherein the pressure difference across the conditioning module 07 decreases with increasing temperature;
in the Reset phase, the Reset module 01 is configured to output an initialization signal Vinit to the first node P1 under the control of the Reset signal terminal Reset; the control module 04 is configured to output a reference signal Vref to the third node P3 under the control of the Reset signal terminal Reset;
in the compensation stage, the write-in module 05 is configured to output the data signal Vdata to the third node P3 under the control of the scan signal Gate; the adjusting module 07 is configured to adjust the voltage signal of the first input terminal of the compensating module 06 according to the voltage signal of the second node P2, or adjust the voltage signal of the third node P3 according to the voltage signal of the output terminal of the controlling module 04, or adjust the voltage signal of the third node P3 according to the voltage signal of the output terminal of the writing module 05; the compensation module 06 is configured to compensate the threshold voltage of the driving module 02 for the first node P1 under the control of the scan signal Gate;
in the light emitting stage, the control module 04 is configured to output a reference signal Vref to the third node P3 under the control of the light emitting control signal EM; the compensation module 06 is configured to adjust the potential of the first node P1 according to the potential of the third node P3; the driving module 02 is used for outputting a power supply signal Vdd to the second node P2 under the control of the first node P1; the switch module 03 is configured to conduct the second node P2 with the input end of the light emitting device OLED under the control of the light emitting control signal EM, so as to drive the light emitting device OLED to emit light.
In the pixel circuit provided by the embodiment of the invention, in the reset stage, the compensation stage and the light-emitting stage, the reset module, the driving module, the switch module, the control module, the writing module and the compensation module in the pixel circuit complete corresponding functions under the control of respective control ends, so that the light-emitting device can be normally driven to emit light; meanwhile, the voltage signal of the first input end or the third node of the compensation module is adjusted through the adjusting module, the compensation module adjusts the voltage of the control end of the driving module according to the voltage signal of the first input end or the third node, and the condition that the driving current output by the driving module increases along with the rise of the temperature is reduced or eliminated, so that the problem of color cast of the display panel caused by high temperature is solved, and the purpose of white balance of the display panel at different temperatures is achieved.
In a specific implementation, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 2a to fig. 2c, the driving module 02 may include: a first switching transistor T1; the first switching transistor T1 has a gate connected to the first node P1, a source for inputting the power signal Vdd, and a drain connected to the second node P2. Specifically, the first switching transistor may be turned on under the control of the first node, and the turned-on first switching transistor may output the power supply signal to the second node.
In a specific implementation, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 2a to fig. 2c, the reset module 01 may include: a second switching transistor T2; the second switching transistor T2 has a gate connected to a Reset signal terminal Reset, a source for inputting an initialization signal Vinit, and a drain connected to the first node P1. Specifically, the second switching transistor may be turned on under the control of the reset signal terminal, and the turned-on second switching transistor may output the initialization signal to the first node, thereby implementing initialization of the first node.
In a specific implementation, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 2a to fig. 2c, the switch module 03 may include: a third switching transistor T3; the third switching transistor T3 has a gate for inputting the emission control signal EM, a source connected to the second node P2, and a drain connected to the input terminal of the light emitting device OLED. Specifically, the third switching transistor may be turned on under the control of the light emission control signal, and the turned-on third switching transistor may turn on the second node and the input terminal of the light emitting device.
In a specific implementation, as shown in fig. 2a to fig. 2c, in the pixel circuit provided in the embodiment of the present invention, the control module 04 may include: a fourth switching transistor T4 and a fifth switching transistor T5; the gate of the fourth switching transistor T4 is connected to the Reset signal terminal Reset, the source is used for inputting the reference signal Vref, and the drain is electrically connected to the third node P3; the gate of the fifth switching transistor T5 is used for inputting the emission control signal EM, the source is used for inputting the reference signal Vref, and the drain is electrically connected to the third node P3. Specifically, the fourth switching transistor may be turned on under the control of the reset signal terminal, and the turned-on fourth switching transistor may output the reference signal to the third node; the fifth switching transistor may be turned on under the control of the light emission control signal, and the turned-on fifth switching transistor may output the reference signal to the third node.
In a specific implementation, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 2a to fig. 2c, the writing module 05 may include: a sixth switching transistor T6; the sixth switching transistor T6 has a Gate for inputting the scan signal Gate, a source for inputting the data signal Vdata, and a drain electrically connected to the third node P3. Specifically, the sixth switching transistor may be turned on under the control of the scan signal, and the turned-on sixth switching transistor may output the data signal to the third node.
In a specific implementation, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 2a to fig. 2c, the compensation module 06 may include: a seventh switching transistor T7 and a capacitor C; a Gate of the seventh switching transistor T7 is used for inputting a scan signal Gate, a source thereof is electrically connected to the second node P2, and a drain thereof is connected to the first node P1; the capacitor C is connected between the first node P1 and the third node P3. Specifically, the seventh switching transistor may be turned on under the control of the scan signal, and the turned-on seventh switching transistor may turn on the first node and the second node.
In practical implementation, in the pixel circuit provided in the embodiment of the present invention, as shown in fig. 2a to fig. 2c, the adjusting module 07 may include: a diode D; the diode D is connected between the first input of the compensation module 06 and the second node P2, as shown in fig. 2 a; or between the output of the control module 04 and the third node P3, as shown in fig. 2 b; or between the output of the write module 05 and the third node P3, as shown in fig. 2 c. Specifically, the diode may be a metal-semiconductor contact diode, as shown in fig. 3, the potential barrier q Φ of which isBHas temperature responsiveness, and can be reduced along with the increase of the temperature.
It should be noted that the switching Transistor mentioned in the above embodiments of the present invention may be a Thin Film Transistor (TFT) or a Metal oxide semiconductor field effect Transistor (MOS), and is not limited herein. In specific implementations, the sources and drains of these transistors may be interchanged without specific distinction. A thin film transistor will be described as an example in describing specific embodiments.
The following describes in detail the working process of the pixel circuit provided by the embodiment of the present invention with reference to the pixel circuit and the working timing provided by the embodiment of the present invention. The operation of the pixel circuit provided by the embodiment of the present invention will be described with reference to the pixel circuit shown in fig. 2a to 2c and the input/output timing diagram shown in fig. 4. Specifically, three stages t1 to t3 in the input-output timing diagram shown in fig. 4 are selected. In the following description, a high level signal is denoted by 1, and a low level signal is denoted by 0.
At stage t1, EM is 1, Reset is 0, and Gate is 1. Since Reset is 0, the second and fourth switching transistors T2 and T4 are turned on. The turned-on second switching transistor T2 outputs the initialization signal Vinit to the first node P1, thereby initializing the first node P1; the turned-on fourth switching transistor T4 outputs the reference signal Vref to the third node P3. Therefore, in the pixel circuit shown in fig. 2a, at the stage t1, the voltages at the left and right ends of the capacitor C are Va ═ Vref, Vb ═ Vinit respectively; in the pixel circuit shown in fig. 2b, at the stage t1, voltages at the left and right ends of the capacitor C are respectively Va ═ Vref-V (V is the voltage difference between the two ends of the diode D), and Vb ═ Vinit; in the pixel circuit shown in fig. 2C, at stage t1, the voltages across the capacitor C are Va ═ Vref and Vb ═ Vinit, respectively.
At stage t2, EM is 1, Reset is 1, and Gate is 0. Since Gate is 0, the sixth and seventh switching transistors T6 and T7 are turned on. In the pixel circuit shown in fig. 2a, the turned-on sixth switching transistor T6 outputs the data signal Vdata to the third node P3, and the turned-on seventh switching transistor T7 turns on one end of the diode D and the first node P1, so that the voltage across the capacitor C at the T2 stage is Va-Vdata, Vb + Vdd-V, respectively; in the pixel circuit shown in fig. 2b, the turned-on sixth switching transistor T6 outputs the data signal Vdata to the third node P3, and the turned-on seventh switching transistor T7 turns on the second node P2 and the first node P1, so that the voltage across the capacitor C at the stage T2 is Va-Vdata, Vb-Vdd + Vth, respectively; in the pixel circuit shown in fig. 2C, the turned-on sixth switching transistor T6 outputs the data signal Vdata to one end of the diode D, and the turned-on seventh switching transistor T7 turns on the second node P2 and the first node P1, so that the voltage across the capacitor C at the stage T2 is Va-Vdata-V, and Vb + Vdd.
At stage t3, EM is 0, Reset is 1, and Gate is 1. Since EM is 0, the third and fifth switching transistors T3 and T5 are turned on. The turned-on third switching transistor T3 turns on the second node P2 and the input terminal of the light emitting device OLED; the turned-on fifth switching transistor T5 outputs the reference signal Vref to the third node P3.
Therefore, in the pixel circuit shown in fig. 2a, at the stage t3, the voltages at the left and right ends of the capacitor C are Va-Vref, Vb-Vref + Vdd + Vth-Vdata-V, respectively, and the driving currents for driving the light emitting device OLED to emit light are:
where μ is the mobility of the carrier in the semiconductor layer of the first on-off transistor T1, which is a driving transistor, Cox is the capacitance of the dielectric layer, and W/L is the width-to-length ratio of the channel of the first on-off transistor T1.
In the pixel circuit shown in fig. 2b, at the stage t3, voltages at the left and right ends of the capacitor C are Va-Vref-V, Vb-Vref-V + Vdd + Vth-Vdata, respectively, and the driving currents for driving the light emitting device OLED to emit light are:
in the pixel circuit shown in fig. 2C, at stage t3, voltages at the left and right ends of the capacitor C are Va-Vref, Vb-Vref + Vdd + Vth + V-Vdata, respectively, and the driving currents for driving the light emitting device OLED to emit light are:
from the above analysis, in the calculation formula of the driving current for the pixel circuit to finally drive the light emitting device OLED to emit light as shown in fig. 2a to 2c, the mobility μ increases with the increase of the temperature, the potential barrier V of the diode decreases with the increase of the temperature, and the decrease of V results in the decrease of (Verf + V-Vdata) or (Vdata + V-Vref), so that the increase and decrease of the whole calculation result can achieve the purpose of maintaining the current stable. V is related to the fermi level of the metal and semiconductor in the diode and these parameters can be adjusted to obtain a more suitable V. In addition, the purpose of stabilizing the driving current can be achieved by adjusting the W/L of the driving transistor and adjusting the voltage value range of Vdata and adjusting the sensitivity of the gold diode.
Based on the same inventive concept, embodiments of the present invention provide a display panel including the pixel circuit provided in embodiments of the present invention. The display panel can be applied to any product or component with a display function, such as a mobile phone, a tablet personal computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like. Since the principle of the display panel to solve the problem is similar to that of the pixel circuit, the implementation of the display panel can refer to the implementation of the pixel circuit, and repeated descriptions are omitted.
The embodiment of the invention provides a pixel circuit and a display panel, wherein the pixel circuit comprises: the device comprises a reset module, a driving module, a switch module, a control module, a writing module, a compensation module, an adjusting module and a light-emitting device; the control end of the reset module is connected with the reset signal end, the input end of the reset module is used for inputting an initialization signal, and the output end of the reset module is connected with the first node; the control end of the driving module is connected with the first node, the input end of the driving module is used for inputting a power supply signal, and the output end of the driving module is connected with the second node; the control end of the switch module is used for inputting a light-emitting control signal, the input end of the switch module is connected with the second node, and the output end of the switch module is connected with the input end of the light-emitting device; the output end of the light-emitting device is used for accessing a low level signal; the first control end of the control module is connected with the reset signal end, the second control end is used for inputting a light-emitting control signal, the input end is used for inputting a reference signal, and the output end is electrically connected with the third node; the control end of the writing module is used for inputting scanning signals, the input end of the writing module is used for inputting data signals, and the output end of the writing module is electrically connected with the third node; the control end of the compensation module is used for inputting scanning signals, the first input end is electrically connected with the second node, the second input end is connected with the third node, and the output end is connected with the first node; the adjusting module is connected between the first input end and the second node of the compensating module; or between the output end of the control module and the third node; or the output end of the writing module is connected with the third node; wherein the pressure difference across the conditioning module decreases with increasing temperature;
in the reset stage, the reset module is used for outputting an initialization signal to the first node under the control of the reset signal end; the control module is used for outputting a reference signal to a third node under the control of the reset signal end;
in the compensation stage, the write-in module is used for outputting the data signal to a third node under the control of the scanning signal; the adjusting module is used for adjusting a voltage signal of a first input end of the compensating module according to a voltage signal of the second node; or adjusting the voltage signal of the third node according to the voltage signal of the output end of the control module; or adjusting the voltage signal of the third node according to the voltage signal of the output end of the write-in module; the compensation module is used for compensating the threshold voltage of the driving module for the first node under the control of the scanning signal;
in the light emitting stage, the control module is used for outputting the reference signal to the third node under the control of the light emitting control signal; the compensation module is used for adjusting the potential of the first node according to the potential of the third node; the driving module is used for outputting a power supply signal to the second node under the control of the first node; the switch module is used for conducting the second node and the input end of the light-emitting device under the control of the light-emitting control signal to drive the light-emitting device to emit light.
Specifically, in the pixel circuit provided in the embodiment of the present invention, in the reset stage, the compensation stage, and the light emitting stage, the reset module, the driving module, the switch module, the control module, the write-in module, and the compensation module in the pixel circuit complete corresponding functions under the control of their respective control terminals, so as to realize normal driving of the light emitting device to emit light; meanwhile, the voltage signal of the first input end or the third node of the compensation module is adjusted through the adjusting module, the compensation module adjusts the voltage of the control end of the driving module according to the voltage signal of the first input end or the third node, and the condition that the driving current output by the driving module increases along with the rise of the temperature is reduced or eliminated, so that the problem of color cast of the display panel caused by high temperature is solved, and the purpose of white balance of the display panel at different temperatures is achieved.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (9)
1. A pixel circuit, comprising: the temperature-controlled LED driving circuit comprises a reset module, a driving module, a switch module, a control module, a writing module, a compensation module, an adjusting module and a light-emitting device, wherein the driving module outputs driving current increased along with the rise of temperature; wherein,
the control end of the reset module is connected with the reset signal end, the input end of the reset module is used for inputting an initialization signal, and the output end of the reset module is connected with the first node;
the control end of the driving module is connected with the first node, the input end of the driving module is used for inputting a power supply signal, and the output end of the driving module is connected with the second node;
the control end of the switch module is used for inputting a light-emitting control signal, the input end of the switch module is connected with the second node, and the output end of the switch module is connected with the input end of the light-emitting device; the output end of the light-emitting device is used for accessing a low level signal;
the first control end of the control module is connected with the reset signal end, the second control end is used for inputting the light-emitting control signal, the input end is used for inputting a reference signal, and the output end is electrically connected with the third node;
the control end of the writing module is used for inputting scanning signals, the input end of the writing module is used for inputting data signals, and the output end of the writing module is electrically connected with the third node;
the control end of the compensation module is used for inputting the scanning signal, the first input end is electrically connected with the second node, the second input end is connected with the third node, and the output end is connected with the first node;
the adjusting module is connected between the first input end of the compensating module and the second node; or between the output end of the control module and the third node; or between the output end of the writing module and the third node; wherein the pressure differential across the conditioning module decreases with increasing temperature;
in a reset phase, the reset module is configured to output the initialization signal to the first node under the control of the reset signal terminal; the control module is used for outputting the reference signal to the third node under the control of the reset signal end;
in a compensation phase, the write module is configured to output the data signal to the third node under the control of the scan signal; the adjusting module is used for adjusting a voltage signal of a first input end of the compensating module according to a voltage signal of the second node, or adjusting a voltage signal of a third node according to a voltage signal of an output end of the control module, or adjusting a voltage signal of the third node according to a voltage signal of an output end of the writing module; the compensation module is used for compensating the threshold voltage of the driving module for the first node under the control of the scanning signal;
in a light emitting phase, the control module is configured to output the reference signal to the third node under the control of the light emitting control signal; the compensation module is used for adjusting the potential of the first node according to the potential of the third node; the driving module is used for outputting the power supply signal to the second node under the control of the first node; the switch module is used for conducting the second node and the input end of the light-emitting device under the control of the light-emitting control signal to drive the light-emitting device to emit light.
2. The pixel circuit of claim 1, wherein the driving module comprises: a first switching transistor;
and the grid electrode of the first switch transistor is connected with the first node, the source electrode of the first switch transistor is used for inputting the power supply signal, and the drain electrode of the first switch transistor is connected with the second node.
3. The pixel circuit of claim 1, wherein the reset module comprises: a second switching transistor;
and the grid electrode of the second switching transistor is connected with the reset signal end, the source electrode of the second switching transistor is used for inputting the initialization signal, and the drain electrode of the second switching transistor is connected with the first node.
4. The pixel circuit of claim 1, wherein the switching module comprises: a third switching transistor;
and the grid electrode of the third switching transistor is used for inputting the light-emitting control signal, the source electrode of the third switching transistor is connected with the second node, and the drain electrode of the third switching transistor is connected with the input end of the light-emitting device.
5. The pixel circuit of claim 1, wherein the control module comprises: a fourth switching transistor and a fifth switching transistor; wherein,
the grid electrode of the fourth switching transistor is connected with the reset signal end, the source electrode of the fourth switching transistor is used for inputting the reference signal, and the drain electrode of the fourth switching transistor is electrically connected with the third node;
the gate of the fifth switching transistor is used for inputting the light-emitting control signal, the source of the fifth switching transistor is used for inputting the reference signal, and the drain of the fifth switching transistor is electrically connected with the third node.
6. The pixel circuit of claim 1, wherein the write module comprises: a sixth switching transistor;
and the grid electrode of the sixth switching transistor is used for inputting the scanning signal, the source electrode of the sixth switching transistor is used for inputting the data signal, and the drain electrode of the sixth switching transistor is electrically connected with the third node.
7. The pixel circuit of claim 1, wherein the compensation module comprises: a seventh switching transistor and a capacitor; wherein,
the grid electrode of the seventh switching transistor is used for inputting the scanning signal, the source electrode of the seventh switching transistor is electrically connected with the second node, and the drain electrode of the seventh switching transistor is connected with the first node;
the capacitor is connected between the first node and the third node.
8. The pixel circuit according to any of claims 1-7, wherein the adjustment module comprises: a diode;
the diode is connected between the first input end of the compensation module and the second node; or between the output end of the control module and the third node; or between the output of the write module and the third node.
9. A display panel comprising the pixel circuit according to any one of claims 1 to 8.
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| US10643542B2 (en) | 2018-03-30 | 2020-05-05 | Wuhan China Star Optoelectronics Semiconductor Display Technology Co., Ltd. | Pixel driving circuit and display device with the same |
| CN108492782A (en) * | 2018-03-30 | 2018-09-04 | 武汉华星光电半导体显示技术有限公司 | A kind of pixel-driving circuit and display device |
| CN110473496B (en) * | 2018-05-09 | 2021-01-26 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof, display substrate and display device |
| CN108877668B (en) * | 2018-07-27 | 2021-01-22 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof and display panel |
| CN110010074B (en) * | 2019-04-28 | 2021-05-07 | 武汉华星光电半导体显示技术有限公司 | Pixel compensation circuit, driving method and display device |
| CN110111723A (en) * | 2019-06-18 | 2019-08-09 | 京东方科技集团股份有限公司 | Pixel circuit and its driving method, display panel |
| TWI712026B (en) * | 2020-02-10 | 2020-12-01 | 友達光電股份有限公司 | Pixel circuit |
| CN113870791B (en) * | 2021-10-11 | 2023-07-25 | 京东方科技集团股份有限公司 | Pixel driving circuit and driving method thereof |
| CN115206230B (en) * | 2022-07-29 | 2023-04-28 | 浙江传媒学院 | Driving circuit and driving control method thereof |
| CN115331615B (en) * | 2022-08-29 | 2023-11-21 | 惠科股份有限公司 | Drive circuit and display panel |
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| CN104280911B (en) * | 2014-09-26 | 2017-04-05 | 京东方科技集团股份有限公司 | A kind of array base palte, display panels and display device |
| TWI536337B (en) * | 2014-12-09 | 2016-06-01 | 友達光電股份有限公司 | Temperature sensing circuit of display device and corresponding operation method |
| CN106409231B (en) * | 2016-10-31 | 2018-10-12 | 昆山国显光电有限公司 | A kind of luminance compensation method, device and display equipment |
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