CN117153098A

CN117153098A - Pixel circuit and display panel

Info

Publication number: CN117153098A
Application number: CN202311117051.8A
Authority: CN
Inventors: 陈杰; 袁海江
Original assignee: HKC Co Ltd
Current assignee: HKC Co Ltd
Priority date: 2023-08-30
Filing date: 2023-08-30
Publication date: 2023-12-01

Abstract

The application provides a pixel circuit and a display panel, wherein the pixel circuit comprises a light emitting module, a driving switch tube, an energy storage module, a reset loop, a threshold compensation loop, a data writing loop and a light emitting loop. The first connecting end of the driving switch tube is used for receiving driving voltage, and the second connecting end is electrically connected with the light emitting module. The first end of the energy storage module is electrically connected with the control end of the driving switch tube. The reset loop is used for conducting in a reset phase to enable the first end of the energy storage module to be grounded and resetting the voltage of the second end of the energy storage module to a driving voltage. The threshold compensation loop is used for conducting in a threshold compensation stage to connect the second end of the energy storage module to the ground and providing a driving voltage to the first end of the energy storage module so that the potential of the first end of the energy storage module changes to the first voltage. The data writing loop is used for conducting the access data voltage in the light-emitting stage and providing the access data voltage to the second end of the energy storage module. The light-emitting loop is used for conducting in a light-emitting stage so that the light-emitting module emits light.

Description

Pixel circuit and display panel

Technical Field

The present application relates to the field of display technologies, and in particular, to a pixel circuit and a display panel.

Background

An OLED (Organic Light-Emitting Diode) is a device that generates electroluminescence using a multi-layer Organic thin film structure, which is easy to manufacture and requires only a low driving voltage, and these characteristics make the OLED very prominent in flat panel display applications. Compared with an LCD display screen, the OLED display screen is lighter and thinner, has high brightness, low power consumption, quick response, high definition, good flexibility and high luminous efficiency, and can meet the new requirements of consumers on display technology.

The light emitting element in each pixel unit in the OLED display panel is driven by a current generated when the driving switching transistor (Thin Film Transistor ) is in a saturated state. Because of limitations in the process, especially the uniformity of the threshold voltage Vth of the driving tube manufactured by the low temperature polysilicon technology is very poor and has drift, that is, the threshold voltages Vth of the driving switching tubes in different pixel units are inconsistent, when the same data voltages are input, the inconsistent threshold voltages Vth will cause inconsistent driving currents in different pixel units, resulting in poor brightness uniformity of the display panel.

Disclosure of Invention

Accordingly, the main purpose of the present application is to provide a pixel circuit and a display panel, which are aimed at solving the problem of poor brightness uniformity of the display panel caused by the non-uniformity of the threshold voltage Vth of the driving switch tube of the light emitting element in each pixel unit in the conventional OLED display panel.

In order to achieve the above object, a first aspect of the present application provides a pixel circuit, which sequentially operates in a reset phase, a threshold compensation phase and a light-emitting phase in a display period of a frame, wherein the pixel circuit includes a light-emitting module, a driving switch tube, an energy storage module, a reset circuit, a threshold compensation circuit, a data writing circuit and a light-emitting circuit. The light emitting module includes a first end and a second end, the first end of the light emitting module being grounded. The driving switch tube comprises a first connecting end, a second connecting end and a control end, wherein the first connecting end is used for receiving driving voltage, and the second connecting end is electrically connected with the second end of the light-emitting module. The energy storage module comprises a first end and a second end, and the first end of the energy storage module is electrically connected with the control end of the driving switch tube. The energy storage module is located in the reset loop, and the reset loop is used for conducting in the reset phase, grounding the first end of the energy storage module, and providing the driving voltage to the second end of the energy storage module so as to reset the voltage of the second end of the energy storage module to the driving voltage. The driving switch tube and the energy storage module are connected in series in the threshold compensation loop, the threshold compensation loop is used for being conducted in the threshold compensation stage, disconnecting the first end of the energy storage module from the electric connection with the ground and connecting the second end of the energy storage module to the ground, so that the driving voltage is provided to the first end of the energy storage module through the driving switch tube, and then the potential of the first end of the energy storage module is changed to a first voltage, wherein the first voltage is the difference between the driving voltage and the threshold voltage of the driving switch tube. The data writing loop is electrically connected with the second end of the energy storage module, and is used for being conducted in the light-emitting stage, accessing data voltage and providing the data voltage to the second end of the energy storage module, so that the energy storage module adjusts the potential of the control end of the driving switch tube to a second voltage based on voltage maintaining characteristics, and the second voltage is the sum of the first voltage and the data voltage. The driving switch tube and the light-emitting module are connected in series in the light-emitting loop, and the light-emitting loop is used for being conducted in the light-emitting stage, so that the driving voltage is provided to the light-emitting module through the driving switch tube, and the light-emitting module emits light. The driving switch tube adjusts the light-emitting brightness of the light-emitting module based on the driving voltage received by the first connecting end and the second voltage received by the control end of the driving switch tube.

According to the pixel circuit provided by the application, the potential of the first end of the energy storage module is regulated to the first voltage through the threshold compensation loop in the threshold compensation stage, and the data voltage is supplied to the second end of the energy storage module through the data writing loop in the light-emitting stage, so that the energy storage module regulates the potential of the control end of the driving switch tube to the second voltage based on the voltage holding characteristic, and the driving switch tube regulates the light-emitting brightness of the light-emitting module based on the driving voltage received by the first connection end and the second voltage received by the control end of the driving switch tube, so that the threshold voltage of the driving switch tube can be compensated, the light-emitting brightness of the light-emitting module is irrelevant to the threshold voltage, and the problem of uneven display brightness caused by different threshold voltages of the driving switch tubes in different pixel circuits can be solved.

Optionally, the pixel circuit further includes a first switching tube located in the reset loop, the first switching tube includes a first connection end, a second connection end and a control end, the first connection end of the first switching tube is grounded, and the second connection end of the first switching tube is electrically connected with the first end of the energy storage module. In the reset stage, the first switching tube is conducted based on a first scanning signal received by the control end of the first switching tube, so that the first end of the energy storage module is grounded through the conducted first switching tube.

Optionally, the pixel circuit further includes a second switching tube located in the reset loop, where the second switching tube includes a first connection end, a second connection end, and a control end, the first connection end of the second switching tube is used to receive the driving voltage, and the second connection end of the second switching tube is electrically connected with the second end of the energy storage module. In the reset phase, the first switching tube is conducted based on a first scanning signal received by the control end of the first switching tube, and the second switching tube is conducted based on a second scanning signal received by the control end of the second switching tube, so that the reset loop is conducted.

Optionally, the driving voltage is high level, and the driving switch tube is a low level conducting switch tube. The pixel circuit further comprises a third switching tube located in the threshold compensation loop, the third switching tube comprises a first connecting end, a second connecting end and a control end, the first connecting end of the third switching tube is grounded, and the second connecting end of the third switching tube is electrically connected with the second end of the energy storage module. In the threshold compensation stage, the third switching tube is conducted based on a third scanning signal received by the control end of the third switching tube, so that the second end of the energy storage module is grounded through the conducted third switching tube, and the energy storage module adjusts the potential of the control end of the driving switching tube to a third voltage based on the voltage maintaining characteristic, and then the driving switching tube is conducted. Wherein the third voltage is a difference between a ground potential and the driving voltage.

Optionally, the pixel circuit further includes a fourth switching tube located in the threshold compensation loop, where the fourth switching tube includes a first connection end, a second connection end, and a control end, the first connection end of the fourth switching tube is electrically connected with the second connection end of the driving switching tube, and the second connection end of the fourth switching tube is electrically connected with the first end of the energy storage module. In the threshold compensation stage, the third switching tube is turned on based on a third scanning signal received by a control end thereof, the driving switching tube is turned on based on the third voltage received by the control end thereof, and the fourth switching tube is turned on based on a fourth scanning signal received by the control end thereof, thereby turning on the threshold compensation loop.

Optionally, the pixel circuit further includes a fifth switching tube located in the light-emitting loop, where the fifth switching tube includes a first connection end, a second connection end, and a control end, the first connection end of the fifth switching tube is electrically connected with the second connection end of the driving switching tube, and the second connection end of the fifth switching tube is electrically connected with the second end of the light-emitting module. In the light emitting stage, the driving switching tube is turned on based on the second voltage received by the control end of the driving switching tube, and the fifth switching tube is turned on based on a fifth scanning signal received by the control end of the fifth switching tube, so that the light emitting loop is turned on.

Optionally, the pixel circuit further includes a data writing switch tube located in the data writing loop, the data writing switch tube includes a first connection end, a second connection end and a control end, the first connection end of the data writing switch tube is used for receiving a data voltage, and the second connection end of the data writing switch tube is electrically connected with the second end of the energy storage module. In the light-emitting stage, the data writing switch tube is conducted based on a data writing control signal received by the control end of the data writing switch tube, so that the second end of the energy storage module receives the data voltage through the conducted data writing switch tube.

Optionally, the pixel circuit further includes a voltage follower located in the data writing loop, the voltage follower includes an input end and an output end, the input end of the voltage follower is electrically connected with the second connection end of the data writing switch tube, and the output end of the voltage follower is electrically connected with the second end of the energy storage module.

Optionally, the pixel circuit further includes a data write control circuit for generating the data write control signal, and the data write control circuit includes a sixth switching transistor, a comparator, and a D flip-flop. The sixth switching tube comprises a first connecting end, a second connecting end and a control end, and the first connecting end of the sixth switching tube is electrically connected with the first end of the energy storage module. The comparator comprises a normal phase input end, an opposite phase input end and an output end, wherein the normal phase input end of the comparator is electrically connected with the second connection end of the sixth switching tube, the opposite phase output end of the comparator is grounded, and the comparator is used for outputting a corresponding comparison signal according to the relation between the voltage of the normal phase input end and the voltage of the opposite phase input end. The D trigger comprises a D input end, a clock signal input end and a Q output end, wherein the D input end of the D trigger is used for receiving trigger voltage with a constant voltage value, the clock signal input end of the D trigger is electrically connected with the output end of the comparator, the clock signal input end of the D trigger is used for receiving the comparison signal output by the output end of the comparator, the Q output end of the D trigger is electrically connected with the data writing switch tube, and the D trigger responds to level jump of the comparison signal and outputs the trigger voltage through the Q output end. In the light-emitting stage, the sixth switching tube is conducted based on a sixth scanning signal received by the control end of the sixth switching tube, so that the comparator is electrically connected with the first end of the energy storage module through the conducted sixth switching tube, the comparison signal output by the comparator jumps from low level to high level, and the D trigger responds to the comparison signal and jumps from low level to high level to output the trigger voltage through the Q output end. The data writing control signal output by the data writing control circuit is the trigger voltage output by the Q output end of the D trigger.

The second aspect of the present application also provides a display panel, which includes the pixel circuit, the data driver, and the scan driver described in the first aspect. The data driver is used for generating data voltages and outputting the data voltages to the pixel circuits. The scanning driver is used for generating a plurality of scanning signals and outputting the scanning signals to the pixel circuit so as to drive the pixel circuit to sequentially work in a reset phase, a threshold compensation phase and a light-emitting phase in a display period of one frame of picture.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Drawings

FIG. 1 is a schematic diagram of a conventional pixel circuit;

fig. 2 is a schematic structural diagram of a pixel circuit according to an embodiment of the present application;

FIG. 3 is a timing diagram illustrating operation of the pixel circuit shown in FIG. 2 during a display period of a frame;

fig. 4 is a circuit schematic of the pixel circuit shown in fig. 2 in a reset phase J1;

FIG. 5 is a circuit schematic of the pixel circuit shown in FIG. 2 during a threshold compensation phase J2;

fig. 6 is a circuit schematic of the pixel circuit shown in fig. 2 in the light emitting phase J3;

Fig. 7 is a schematic structural diagram of a display panel according to an embodiment of the present application.

The reference numerals are explained as follows:

pixel circuits 100, 100'

Light emitting module L

Drive switch tube M1

Energy storage module C

Reset loop H1

Threshold compensation loop H2

Luminous loop H3

Drive voltage VCC

Data voltage Vdata

Trigger voltage VCR

First voltage V1

Second voltage V2

Third voltage V3

First end G

Second end N

First switching tube T1

Second switching tube T2

Third switching tube T3

Fourth switching tube T4

Data write switch tube M2

Fifth switch tube T5

Sixth switching tube T6

Data write control circuit 10

Data write loop 20

Voltage follower U1

Comparator U2

D flip-flop U3

Scanning signal S0

First scan signal S1

Second scanning signal S2

Third scanning signal S3

Fourth scanning signal S4

Fifth scan signal S5

Sixth scanning signal S6

Reset phase J1

Threshold compensation phase J2

Light emitting stage J3

Display panel 1

Substrate 1000

Display area 1001

Non-display area 1002

Data driver 120

Scan driver 110

Scanning line 111

Data line 121

The application will be further described in the following detailed description in conjunction with the above-described figures.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without any inventive effort, are intended to be within the scope of the application.

In the description of the present application, it should be noted that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Referring to fig. 1, fig. 1 is a conventional pixel circuit 100 'with a 2T1C structure, and the pixel circuit 100' includes a scan switch tube T0, a driving switch tube M1, an energy storage module C, and a light emitting module L.

Wherein the pixel circuit 100' is used for driving the light emitting module L to emit light. The first end of the light emitting module L is grounded. The source electrode of the driving switch tube M1 is configured to receive a driving voltage VCC, the drain electrode of the driving switch tube M1 is electrically connected to the second end of the light emitting module L, the gate electrode of the driving switch tube M1 is electrically connected to the source electrode of the scanning switch tube T0, the source electrode of the scanning switch tube T0 is configured to receive a data voltage Vdata, and the gate electrode of the scanning switch tube T0 is configured to receive a scanning signal S0. The first end of the energy storage module C is electrically connected to the grid electrode of the driving switch tube M1, and the second end of the energy storage module C is electrically connected to the second end of the light emitting module L. For example, when the scan signal is an on signal, the scan switch tube T0 is turned on, the data voltage Vdata on the data line 121 charges the energy storage module C through the scan switch tube T0 to adjust the potential of the first end of the energy storage module C to the data voltage Vdata, the driving switch tube M1 drives the light emitting module L to emit light based on the data voltage Vdata received by the gate thereof and the driving voltage VCC received by the source thereof, and at this time, the source gate voltage vsg=vs-vg=vcc-Vdata of the driving switch tube M1, the driving current Ids flowing through the light emitting module L has the following relationship with the source gate voltage Vsg of the driving switch tube M1:

Ids＝(K/2)(Vsg-Vth) ² ＝(K/2)(VCC-Vdata-Vth) ²

Wherein k=cox×μ×w/L, cox is the gate capacitance per unit area; μ is the mobility of channel electron movement; W/L is the width-to-length ratio of the channel of the driving switch tube M1; vth is a threshold voltage Vth of the driving switching transistor M1.

It will be appreciated that the luminance of the light emitting module L is proportional to the driving current Ids flowing therethrough, i.e., is related to the data voltage Vdata, the driving voltage VCC, and the threshold voltage Vth of the driving switching transistor M1. Since the uniformity of the threshold voltage Vth of the driving switching transistor M1 is poor, that is, the threshold voltages Vth of the driving switching transistors M1 are not uniform in different pixel circuits 100', when the same data voltages are input, the driving currents Ids are not uniform in different pixel circuits 100' due to the non-uniformity of the threshold voltages Vth, resulting in poor brightness uniformity of the display panel.

In view of this, referring to fig. 2, in order to solve the problem of poor uniformity of the brightness of the display panel caused by poor uniformity of the threshold voltage Vth of the driving switch transistor M1 of the conventional pixel circuit 100', the present application provides a pixel circuit 100, in which the pixel circuit 100 sequentially operates in a reset phase J1, a threshold compensation phase J2 and a light-emitting phase J3 in a display period of one frame of picture.

The pixel circuit 100 includes a light emitting module L, a driving switch M1, an energy storage module C, a reset circuit H1, a threshold compensation circuit H2, a light emitting circuit H3, and a data writing circuit H4.

The light emitting module L comprises a first end and a second end, and the first end of the light emitting module L is grounded.

The driving switch tube M1 comprises a first connecting end, a second connecting end and a control end, wherein the first connecting end of the driving switch tube M1 is used for receiving driving voltage VCC, and the second connecting end of the driving switch tube M1 is electrically connected with the second end of the light emitting module L.

The energy storage module C comprises a first end G and a second end N, and the first end G of the energy storage module C is electrically connected with the control end of the driving switch tube M1.

The energy storage module C is located in the reset circuit H1, and the reset circuit H1 is configured to conduct in the reset phase J1, to ground the first end G of the energy storage module C, and to provide the driving voltage VCC to the second end N of the energy storage module C, so as to reset the voltage of the second end N of the energy storage module C to the driving voltage VCC.

The driving switch tube M1 and the energy storage module C are connected in series in the threshold compensation loop H2, where the threshold compensation loop H2 is configured to conduct in the threshold compensation stage J2, disconnect the connection between the first end G of the energy storage module C and ground, and connect the second end N of the energy storage module C to ground, so that the driving voltage VCC is provided to the first end G of the energy storage module C through the driving switch tube M1, and further, the potential of the first end G of the energy storage module C is changed to a first voltage V1, where the first voltage V1 is a difference between the driving voltage VCC and the threshold voltage Vth of the driving switch tube M1, that is, v1=vcc-Vth.

The data writing circuit H4 is electrically connected to the second end N of the energy storage module C, and the data writing circuit H4 is configured to be turned on in the lighting phase J3, and to be connected to a data voltage Vdata and provided to the second end N of the energy storage module C, so that the energy storage module C adjusts the potential of the control end of the driving switch tube M1 to a second voltage V2 based on a voltage holding characteristic, where the second voltage V2 is a sum of the first voltage V1 and the data voltage Vdata, that is:

V2＝V1+Vdata＝VCC-Vth+Vdata。

the driving switch tube M1 and the light emitting module L are connected in series in the light emitting loop H3, and the light emitting loop H3 is configured to be turned on in the light emitting stage J3, so that the driving voltage VCC is provided to the light emitting module L through the driving switch tube M1, so that the light emitting module L emits light. The driving switch tube M1 adjusts the light emitting brightness of the light emitting module L based on the driving voltage VCC received by the first connection end and the second voltage V2 received by the control end.

In the embodiment of the present application, the driving voltage VCC is high, the driving switch tube M1 is a transistor with a low-level conductive state, such as a PMOS transistor, and the first connection end, the second connection end and the control end of the driving switch tube M1 are in one-to-one correspondence with the source, the drain and the gate of the PMOS transistor. The light emitting modules L are OLED, and the first ends and the second ends of the light emitting modules L are in one-to-one correspondence with the cathode and the anode of the OLED. In other embodiments, the Light Emitting module may also be an LED (Light-Emitting Diode), a Micro LED (Micro Light-Emitting Diode), or a Mini LED (Micro Light-Emitting Diode). The energy storage module C is an energy storage capacitor.

It should be noted that, in the reset phase J1, since the reset circuit H1 connects the first terminal G of the energy storage module C to the ground, the voltage of the second terminal N of the energy storage module C is reset to the driving voltage VCC, at this time, the voltage vg1=0 of the first terminal G, the voltage VN 1=vcc of the second terminal N, and the voltage Δv1=vg1-VN 1=0-vcc= -VCC of the first terminal G and the second terminal N of the energy storage module C.

At the beginning of the threshold compensation phase J2, the first end G of the energy storage module C is electrically disconnected from ground, while the second end N of the energy storage module C is grounded, i.e. the voltage VN 2=0 of the second end N, and the potential of the first end G changes to a third voltage V3 due to the voltage holding characteristic of the energy storage module C (i.e. the voltage between the two ends of the capacitor cannot be suddenly changed), wherein the third voltage V3 is the difference between the ground potential and the driving voltage VCC, i.e.

V20=v3=v2+Δv1= -VCC, so that the driving switching tube M1 is turned on. In the threshold compensation phase J2, the threshold compensation loop H2 that is turned on is connected to the driving voltage VCC through the first terminal of the driving switch tube M1 and is provided to the first terminal G of the energy storage module C, so that the potential of the first terminal G of the energy storage module C is continuously increased until the first voltage V1, at this time, the source gate voltage vsg=vcc-v1=vth of the driving switch tube M1 just enters a state close to the off state, and thus the potential of the first terminal G of the energy storage module C is not changed but remains V1, that is, vg2=v1=vcc-Vth, and the voltage Δv2=vg2=vcc-Vth between the first terminal G and the second terminal N of the energy storage module C.

In the lighting phase J3, the data writing circuit H4 is turned on to adjust the potential of the second end N of the energy storage module C to the data voltage Vdata, that is, vn3=vdata, and since the energy storage module C has the voltage maintaining characteristic, the potential of the first end G changes to the second voltage V2, that is:

VG3＝V2＝VN3+ΔV2＝Vdata+VCC-Vth。

the light emitting circuit H3 is turned on, and the driving switch tube M1 adjusts the light emitting brightness of the light emitting module L based on the driving voltage VCC received by the first connection end and the second voltage V2 received by the control end thereof, that is, the driving switch tube M1 adjusts the magnitude of the driving current Ids flowing through the light emitting module L according to the magnitude of the source gate voltage Vsg thereof, thereby adjusting the light emitting brightness of the light emitting module L. Specifically, according to the operation characteristics of the transistor, the following relationship exists between the driving current Ids and the source gate voltage Vsg:

Ids＝(K/2)(Vsg-Vth) ² ＝(K/2)[VCC-(Vdata+VCC-Vth)-Vth] ² ＝(K/2)(-Vdata) ² 。

wherein k=cox×μ×w/L, cox is the gate capacitance per unit area; μ is the mobility of channel electron movement; W/L is the width-to-length ratio of the channel of the driving switch tube M.

As can be seen from the above formula, the threshold compensation circuit H2 can compensate the voltage of the control terminal of the driving switch tube M1 to the first voltage V1 in the threshold compensation phase J2, and the data writing circuit H4 can provide the data voltage Vdata to the second terminal N of the energy storage module C in the light emitting phase J3, so that the energy storage module C adjusts the potential of the control terminal of the driving switch tube M1 to the second voltage V2 based on the voltage maintaining characteristic, and the driving current Ids flowing through the light emitting module L is independent of the threshold voltage Vth of the driving switch tube M1, thereby solving the problem of uneven display brightness caused by different threshold voltages Vth of the driving switch tube M1 in different pixel circuits 100.

According to the pixel circuit 100 provided by the application, the potential of the first end G of the energy storage module C is regulated to the first voltage V1 through the threshold compensation loop H2 in the threshold compensation stage J2, and the data voltage Vdata is provided to the second end N of the energy storage module C through the data writing loop H4 in the light-emitting stage J3, so that the potential of the control end of the driving switch tube M1 is regulated to the second voltage V2 by the energy storage module C based on the voltage maintaining characteristic, and the light-emitting brightness of the light-emitting module L is regulated by the driving switch tube M based on the driving voltage VCC received by the first connection end and the second voltage V2 received by the control end of the driving switch tube M, so that the threshold voltage Vth of the driving switch tube M1 can be compensated, the light-emitting brightness of the light-emitting module L is irrelevant to the threshold voltage Vth, and the problem of uneven display brightness caused by different threshold voltages Vth of the driving switch tubes M1 in different pixel circuits 100 can be solved.

For a more detailed description of the circuit structure and the operation principle of the pixel circuit 100, please refer to fig. 3-6. Fig. 3 is a timing chart of the operation of the pixel circuit 100 in a display period of a frame, fig. 4 is a circuit schematic of the pixel circuit 100 in a reset phase J1, fig. 5 is a circuit schematic of the pixel circuit 100 in a threshold compensation phase J2, and fig. 6 is a circuit schematic of the pixel circuit 100 in a light emitting phase J3.

As shown in fig. 4, the pixel circuit 100 further includes a first switching tube T1 located in the reset circuit H1, where the first switching tube T1 includes a first connection end, a second connection end, and a control end, the first connection end of the first switching tube T1 is grounded, and the second connection end of the first switching tube T1 is electrically connected to the first end G of the energy storage module C.

In the reset phase J1, the first switching tube T1 is turned on based on the first scan signal S1 received by the control end thereof, so that the first end G of the energy storage module C is grounded through the turned-on first switching tube T1.

Further, the pixel circuit 100 further includes a second switching tube T2 located in the reset circuit H1, where the second switching tube T2 includes a first connection end, a second connection end, and a control end, the first connection end of the second switching tube T2 is configured to receive the driving voltage VCC, and the second connection end of the second switching tube T2 is electrically connected to the second end N of the energy storage module C.

The second switching tube T2, the energy storage module C and the first switching tube T1 are sequentially connected in series to form the reset loop H1, and in the reset phase J1, the first switching tube T1 is turned on based on the first scanning signal S1 received by the control end thereof, and the second switching tube T2 is turned on based on the second scanning signal S2 received by the control end thereof, so as to turn on the reset loop H1.

As shown in fig. 5, the pixel circuit 100 further includes a third switching tube T3 located in the threshold compensation loop H2, where the third switching tube T3 includes a first connection end, a second connection end, and a control end, the first connection end of the third switching tube T3 is grounded, and the second connection end of the third switching tube T3 is electrically connected to the second end N of the energy storage module C.

In the threshold compensation phase J2, the third switching tube T3 is turned on based on the third scanning signal S3 received by the control end thereof, so that the second end N of the energy storage module C is grounded through the turned-on third switching tube T3, and the energy storage module C adjusts the potential of the control end of the driving switching tube M1 to the third voltage V3 based on the voltage maintaining characteristic, and further, the driving switching tube M1 is turned on.

Further, the pixel circuit 100 further includes a fourth switching tube T4 located in the threshold compensation loop H2, where the fourth switching tube T4 includes a first connection end, a second connection end, and a control end, the first connection end of the fourth switching tube T4 is electrically connected to the second connection end of the driving switching tube M1, and the second connection end of the fourth switching tube T4 is electrically connected to the first end G of the energy storage module C.

The driving switch tube M1, the fourth switch tube T4, the energy storage module C and the third switch tube T3 are sequentially connected in series to form the threshold compensation loop H2. In the threshold compensation phase J2, the third switching tube T3 is turned on based on the third scan signal S3 received by the control terminal thereof, the driving switching tube M1 is turned on based on the third voltage V3 received by the control terminal thereof, and the fourth switching tube T4 is turned on based on the fourth scan signal S4 received by the control terminal thereof, thereby turning on the threshold compensation loop H2.

As shown in fig. 6, the pixel circuit 100 further includes a data writing switch tube M2 located in the data writing loop H4, where the data writing switch tube M2 includes a first connection end, a second connection end, and a control end, the first connection end of the data writing switch tube M2 is configured to receive the data voltage Vdata, and the second connection end of the data writing switch tube M2 is electrically connected to the second end N of the energy storage module C.

In the lighting phase J3, the data writing switch M2 is turned on based on the data writing control signal received by the control end thereof, so that the second end N of the energy storage module C receives the data voltage Vdata through the turned-on data writing switch M2.

Further, the pixel circuit 100 further includes a voltage follower U1, where the voltage follower U1 includes an input end and an output end, the input end of the voltage follower U1 is electrically connected to the second connection end of the data writing switch tube M2, and the output end of the voltage follower U1 is electrically connected to the second end N of the energy storage module C.

The data writing switch tube M2 and the voltage follower U1 are sequentially connected in series to form the data writing loop H4, where the data writing loop H4 is used for being turned on in the lighting phase J3, accessing the data voltage Vdata, and providing the data voltage Vdata to the second end N of the energy storage module C.

It should be noted that, the voltage follower U1 is disposed between the data writing switch tube M2 and the second end N of the energy storage module C, so that on one hand, the signal driving force of the data writing loop H4 can be improved, that is, the loss of the data voltage Vdata in the transmission process is reduced, thereby effectively ensuring the accuracy of the data voltage Vdata received by the pixel circuit 100, and further realizing the precise control of the light emitting brightness of the light emitting module L, and on the other hand, the voltage follower U1 can play a role of impedance transformation, so that the following pixel circuit 100 and the preceding data voltage transmission circuit do not affect each other.

Further, the pixel circuit 100 further includes a fifth switching tube T5 located in the light emitting loop H3, where the fifth switching tube T5 includes a first connection end, a second connection end, and a control end, the first connection end of the fifth switching tube T5 is electrically connected to the second connection end of the driving switching tube M1, and the second connection end of the fifth switching tube T5 is electrically connected to the second end of the light emitting module L.

The driving switch tube M1, the fifth switch tube T5 and the light-emitting module L are sequentially connected in series to form the light-emitting loop. In the light emitting period J3, the driving switching tube M1 is turned on based on the second voltage V2 received by the control terminal thereof, and the fifth switching tube T5 is turned on based on the fifth scan signal S5 received by the control terminal thereof, thereby turning on the light emitting circuit H3.

Further, the pixel circuit 100 further includes a data write control circuit 10 for generating the data write control signal, and the data write control circuit 10 includes a sixth switching tube T6, a comparator U2, and a D flip-flop U3.

The sixth switching tube T6 includes a first connection end, a second connection end, and a control end, where the first connection end of the sixth switching tube T6 is electrically connected to the first end G of the energy storage module C.

The comparator U2 comprises a non-inverting input end, an inverting input end and an output end, the non-inverting input end of the comparator U2 is electrically connected with the second connection end of the sixth switching tube T6, the inverting output end of the comparator U2 is grounded, and the comparator U2 is used for outputting a corresponding comparison signal according to the relation between the voltage of the non-inverting input end and the voltage of the inverting input end.

The D trigger U3 comprises a D input end, a clock signal input end and a Q output end, wherein the D input end of the D trigger U3 is used for receiving a trigger voltage VCR with a constant voltage value, the clock signal input end of the D trigger U3 is electrically connected with the output end of the comparator U2, the clock signal input end of the D trigger U3 is used for receiving a comparison signal output by the output end of the comparator U2, the Q output end of the D trigger U3 is electrically connected with the data writing switch tube M2, and the D trigger U3 responds to the level jump of the comparison signal and outputs the trigger voltage VCR through the Q output end.

In the lighting phase J3, the sixth switching tube T6 is turned on based on the sixth scanning signal S6 received by the control end thereof, so that the comparator U2 is electrically connected to the first end G of the energy storage module C through the turned-on sixth switching tube T6, so that the comparison signal output by the comparator U2 jumps from low level to high level, and further the D flip-flop U3 responds to the comparison signal and jumps from low level to high level to output the trigger voltage VCR through the Q output end. The data writing control signal output by the data writing control circuit 10 is the trigger voltage VCR output by the Q output end of the D flip-flop U3.

It should be noted that, since the comparison signal output by the comparator U2 when the voltage at the non-inverting input terminal is higher than the voltage at the inverting input terminal is a high level signal, and the comparison signal output by the comparator U2 when the voltage at the inverting input terminal is higher than the voltage at the input terminal Yu Zhengxiang is a low level signal, before the light-emitting period J3, the sixth switching tube T6 is turned off, so that the comparison signal output by the comparator U2 is a low level, and at the start time of the light-emitting period J3, the potential of the first end G of the energy storage module C is the first voltage V1>0, so that the comparison signal output by the comparator U2 jumps from a low level to a high level, so that the D flip-flop U3 outputs the trigger voltage VCR through the Q output terminal, and further, the data writing switching tube M2 is turned on and the data voltage Vdata is provided to the second end N of the energy storage module C.

It will be appreciated that, since the scan lines themselves in the display panel have resistances and parasitic capacitances, there is an RC delay in the transmission process of the scan signals, the scan signals received by the switch tubes in the pixel circuit 100 are not actually ideal square wave signals, so that the switch tubes are not instantaneously completely turned on when the scan signals are received, but gradually turned on, and thus if the sixth scan signal S6 is directly used as the data writing control signal, the turn-on speed of the data writing switch tube M2 will be slower, thereby affecting the light emitting effect of the light emitting module L. According to the embodiment of the application, by setting the data writing control circuit 10, when the sixth switching tube T6 responds to the sixth scanning signal S6 at a small opening degree, the comparison signal output by the comparator U2 can jump from a low level to a high level, so that the D trigger U3 outputs the trigger voltage VCR to the data writing switching tube M2, and since the voltage value of the trigger voltage VCR is constant, the data writing switching tube M2 can be completely opened to provide the data voltage Vdata to the second end N of the energy storage module C at the moment of receiving the trigger voltage VCR, thereby eliminating the influence of RC delay of the scanning signal on the writing speed of the data voltage Vdata, and further improving the display effect of the light emitting module L.

It should be noted that, in other embodiments, the first connection terminal of the sixth switching tube T6 may be electrically connected to other components having a high potential, but not to the first terminal G of the energy storage module C, for example, the first connection terminal of the sixth switching tube T6 may directly receive the driving voltage VCC.

In the embodiment of the present application, the first to sixth switching transistors T1 to T6 and the data writing switching transistor M2 are all high-level turned-on transistors, and each switching transistor in the embodiment of the present application may be an amorphous silicon thin film transistor (a-Si TFT), a low temperature polysilicon thin film transistor (LTPS TFT), or an Oxide semiconductor thin film transistor (Oxide TFT). Among them, an active layer of the Oxide semiconductor thin film transistor employs an Oxide semiconductor (Oxide), such as indium gallium zinc Oxide (Indium Gallium Zinc Oxide, IGZO). Of course, in other embodiments, the first to sixth switching transistors T1 to T6 and the data writing switching transistor M2 may be low-level turned-on transistors, which is not limited herein.

The following describes in detail the working procedure of the pixel circuit 100 in the display period of one frame of picture according to the present application with reference to fig. 3 to 6:

In the embodiment of the application, each switching tube is independently provided with a scanning signal for control, and in other embodiments, the switching tubes with the same conduction time sequence can share one scanning signal, so that the wiring structure can be simplified. For example, the first switching tube T1 and the second switching tube T2 may share the first scan signal S1, the third switching tube T3 and the fourth switching tube T4 may share the third scan signal S3, and the fifth switching tube T5 and the sixth switching tube T6 may share the fifth scan signal S5.

In the reset phase J1, the first scan signal S1 and the second scan signal S2 are both at high level, and the other scan signals are both at low level. Therefore, the first switching tube T1 and the second switching tube T2 are all turned on, and the third switching tube T3, the fourth switching tube T4, the fifth switching tube T5, the sixth switching tube T6, and the data writing switching tube M2 are all turned off, so that the reset circuit H1 is turned on to reset the voltage of the second end N of the energy storage module C to the driving voltage VCC, and the first end G is grounded, and at this time, since the control end of the driving switching tube M1 is at the ground potential, the driving switching tube M1 is turned on.

In the threshold compensation phase J2, the third scan signal S3 and the fourth scan signal S4 are both high level, and the other scan signals are both low level. Therefore, the third switching tube T3 and the fourth switching tube T4 are all turned on, and the first switching tube T1, the second switching tube T2, the fifth switching tube T5, the sixth switching tube T6 and the data writing switching tube M2 are all turned off, so that the threshold compensation circuit H2 is turned on to provide the driving voltage VCC to the first end G of the energy storage module C, and the potential of the first end G of the energy storage module C is changed to the first voltage V1.

In the light emitting phase J3, the fifth scan signal S5 and the sixth scan signal S6 are both at high level, and the other scan signals are both at low level. Therefore, the fifth switching tube T5, the sixth switching tube T6, the driving switching tube M1 and the data writing switching tube M2 are all turned on, the first switching tube T1, the second switching tube T2, the third switching tube T3 and the fourth switching tube T4 are all turned off, so that the data writing loop H4 is turned on, the data voltage Vdata is provided to the second end N of the energy storage module C, the energy storage module C is further caused to regulate the potential of the control end of the driving switching tube M1 to the second voltage V2 based on the voltage maintaining characteristic, the light emitting loop H3 is caused to be turned on, the driving voltage VCC is provided to the light emitting module L, and at this time, the driving switching tube M1 regulates the light emitting of the light emitting module L based on the driving voltage VCC received by the first connection end and the second voltage V2 received by the control end thereof.

Referring to fig. 7, the present application further provides a display panel 1, where the display panel 1 includes a scan driver 110, a data driver 120, and a plurality of pixel circuits 100 according to any of the above embodiments.

The data driver 120 is configured to generate a data voltage Vdata and output the data voltage Vdata to the pixel circuit 100.

The scan driver 110 is configured to generate a plurality of scan signals and output the scan signals to the pixel circuit 100 to drive the pixel circuit 100 to sequentially operate in a reset phase J1, a threshold compensation phase J2 and a light emitting phase J3 in a display period of one frame of picture.

Further, the display panel 1 includes a substrate 1000, and the substrate 1000 includes a display region 1001 and a non-display region 1002. Wherein, a plurality of the pixel circuits 100 are arranged in the display area 1001 in an array manner.

The display panel 1 further includes a plurality of scan lines 111 extending along a row direction and electrically connected to the scan driver 110, and a plurality of data lines 121 extending along a column direction and electrically connected to the data driver 120, wherein the pixel circuits 100 located in a same column are electrically connected to a corresponding one of the data lines 121, and the pixel circuits 100 located in a same row are electrically connected to a corresponding plurality of scan lines 111. Wherein the number of scan lines 111 electrically connected to the pixel circuits 100 in each row corresponds to the number of scan signals received by the pixel circuits 100.

The data driver 120 outputs the data voltage Vdata to the pixel circuits 100 of each column through the plurality of data lines 121, and the scan driver 110 outputs the plurality of scan signals to the pixel circuits 100 of each row through the plurality of scan lines 111.

According to the pixel circuit 100 in the display panel 1 provided by the application, the potential of the first end G of the energy storage module C is regulated to the first voltage V1 through the threshold compensation loop H2 in the threshold compensation stage J2, and the data voltage Vdata is provided to the second end N of the energy storage module C through the data writing loop H4 in the light-emitting stage J3, so that the energy storage module C regulates the potential of the control end of the driving switch tube M1 to the second voltage V2 based on the voltage maintaining characteristic, and the driving switch tube M regulates the light-emitting brightness of the light-emitting module L based on the driving voltage VCC received by the first connection end and the second voltage V2 received by the control end thereof, so that the threshold voltage Vth of the driving switch tube M1 can be compensated, and the light-emitting brightness of the light-emitting module L is irrelevant to the threshold voltage Vth, thereby solving the problem of uneven display brightness caused by different threshold voltages Vth of the driving switch tubes M in different pixel circuits 100.

It will be evident to those skilled in the art that the application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. Several of the units or means recited in the apparatus claims may also be embodied by one and the same unit or means, either in software or hardware.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the application, the scope of which is defined by the claims and their equivalents.

Claims

1. A pixel circuit, wherein the pixel circuit sequentially operates in a reset phase, a threshold compensation phase, and a light emission phase in a display period of a frame of picture, the pixel circuit comprising:

a light emitting module comprising a first end and a second end, the first end of the light emitting module being grounded;

the driving switch tube comprises a first connecting end, a second connecting end and a control end, wherein the first connecting end is used for receiving driving voltage, and the second connecting end is electrically connected with the second end of the light-emitting module;

the energy storage module comprises a first end and a second end, and the first end of the energy storage module is electrically connected with the control end of the driving switch tube;

the reset circuit is used for being conducted in the reset phase, connecting the first end of the energy storage module to the ground, and providing the driving voltage to the second end of the energy storage module so as to reset the voltage of the second end of the energy storage module to the driving voltage;

the threshold compensation loop is used for being conducted in the threshold compensation stage, disconnecting the first end of the energy storage module from the ground and connecting the second end of the energy storage module to the ground, so that the driving voltage is provided to the first end of the energy storage module through the driving switch tube, and the potential of the first end of the energy storage module is changed to a first voltage, wherein the first voltage is the difference between the driving voltage and the threshold voltage of the driving switch tube;

The data writing loop is electrically connected with the second end of the energy storage module, and is used for being conducted in the light-emitting stage, accessing data voltage and providing the data voltage to the second end of the energy storage module, so that the energy storage module adjusts the potential of the control end of the driving switch tube to the second voltage based on the voltage maintaining characteristic; wherein the second voltage is a sum of the first voltage and the data voltage; and

the light-emitting circuit is used for being conducted in the light-emitting stage, so that the driving voltage is provided to the light-emitting module through the driving switch tube, and the light-emitting module emits light; the driving switch tube adjusts the light-emitting brightness of the light-emitting module based on the driving voltage received by the first connecting end and the second voltage received by the control end of the driving switch tube.

2. The pixel circuit of claim 1, further comprising a first switching tube in the reset loop, the first switching tube comprising a first connection terminal, a second connection terminal, and a control terminal, the first connection terminal of the first switching tube being grounded, the second connection terminal of the first switching tube being electrically connected to the first terminal of the energy storage module;

In the reset stage, the first switching tube is conducted based on a first scanning signal received by the control end of the first switching tube, so that the first end of the energy storage module is grounded through the conducted first switching tube.

3. The pixel circuit of claim 2, further comprising a second switching tube in the reset loop, the second switching tube comprising a first connection, a second connection, and a control terminal, the first connection of the second switching tube for receiving the drive voltage, the second connection of the second switching tube electrically connected to the second end of the energy storage module;

in the reset phase, the first switching tube is conducted based on a first scanning signal received by the control end of the first switching tube, and the second switching tube is conducted based on a second scanning signal received by the control end of the second switching tube, so that the reset loop is conducted.

4. The pixel circuit of claim 1 wherein the drive voltage is high and the drive switch is a low-turn-on switch;

the pixel circuit further comprises a third switching tube positioned in the threshold compensation loop, the third switching tube comprises a first connecting end, a second connecting end and a control end, the first connecting end of the third switching tube is grounded, and the second connecting end of the third switching tube is electrically connected with the second end of the energy storage module;

In the threshold compensation stage, the third switching tube is conducted based on a third scanning signal received by the control end of the third switching tube, so that the second end of the energy storage module is grounded through the conducted third switching tube, and the energy storage module adjusts the potential of the control end of the driving switching tube to a third voltage based on the voltage maintaining characteristic, and then the driving switching tube is conducted; wherein the third voltage is a difference between a ground potential and the driving voltage.

5. The pixel circuit of claim 4 further comprising a fourth switching tube in the threshold compensation loop, the fourth switching tubes each comprising a first connection, a second connection, and a control terminal, the first connection of the fourth switching tube being electrically connected to the second connection of the drive switching tube, the second connection of the fourth switching tube being electrically connected to the first end of the energy storage module;

in the threshold compensation stage, the third switching tube is turned on based on a third scanning signal received by a control end thereof, the driving switching tube is turned on based on the third voltage received by the control end thereof, and the fourth switching tube is turned on based on a fourth scanning signal received by the control end thereof, thereby turning on the threshold compensation loop.

6. The pixel circuit of claim 1, further comprising a fifth switching tube in the light emitting loop, the fifth switching tube comprising a first connection terminal, a second connection terminal, and a control terminal, the first connection terminal of the fifth switching tube being electrically connected to the second connection terminal of the driving switching tube, the second connection terminal of the fifth switching tube being electrically connected to the second terminal of the light emitting module;

in the light emitting stage, the driving switching tube is turned on based on the second voltage received by the control end of the driving switching tube, and the fifth switching tube is turned on based on a fifth scanning signal received by the control end of the fifth switching tube, so that the light emitting loop is turned on.

7. The pixel circuit of claim 1 further comprising a data write switch tube in the data write loop, the data write switch tube comprising a first connection, a second connection, and a control terminal, the first connection of the data write switch tube for receiving a data voltage, the second connection of the data write switch tube electrically connected to the second end of the energy storage module;

in the light-emitting stage, the data writing switch tube is conducted based on a data writing control signal received by the control end of the data writing switch tube, so that the second end of the energy storage module receives the data voltage through the conducted data writing switch tube.

8. The pixel circuit of claim 7 further comprising a voltage follower in the data write loop, the voltage follower including an input and an output, the input of the voltage follower being electrically connected to the second connection of the data write switch, the output of the voltage follower being electrically connected to the second terminal of the energy storage module.

9. The pixel circuit of claim 7, further comprising a data write control circuit for generating the data write control signal, the data write control circuit comprising:

the sixth switching tube comprises a first connecting end, a second connecting end and a control end, and the first connecting end of the sixth switching tube is electrically connected with the first end of the energy storage module;

the comparator comprises a normal phase input end, an opposite phase input end and an output end, wherein the normal phase input end of the comparator is electrically connected with the second connection end of the sixth switching tube, the opposite phase output end of the comparator is grounded, and the comparator is used for outputting a corresponding comparison signal according to the relation between the voltage of the normal phase input end and the voltage of the opposite phase input end; and

The D trigger comprises a D input end, a clock signal input end and a Q output end, wherein the D input end of the D trigger is used for receiving trigger voltage with a constant voltage value, the clock signal input end of the D trigger is electrically connected with the output end of the comparator, the clock signal input end of the D trigger is used for receiving the comparison signal output by the output end of the comparator, the Q output end of the D trigger is electrically connected with the data writing switch tube, and the D trigger responds to the level jump of the comparison signal and outputs the trigger voltage through the Q output end;

in the light-emitting stage, the sixth switching tube is conducted based on a sixth scanning signal received by the control end of the sixth switching tube, so that the comparator is electrically connected with the first end of the energy storage module through the conducted sixth switching tube, a comparison signal output by the comparator is enabled to jump from a low level to a high level, and the D trigger is enabled to respond to the comparison signal and jump from the low level to the high level, and the trigger voltage is output through the Q output end; the data writing control signal output by the data writing control circuit is the trigger voltage output by the Q output end of the D trigger.

10. A display panel, comprising:

a pixel circuit according to any one of claims 1 to 9;

a data driver for generating a data voltage and outputting the data voltage to the pixel circuit; and

the scanning driver is used for generating a plurality of scanning signals and outputting the scanning signals to the pixel circuit so as to drive the pixel circuit to sequentially work in a reset phase, a threshold compensation phase and a light-emitting phase in a display period of one frame of picture.