TWI747405B - Pixel circuit and driving method thereof - Google Patents

Abstract

A pixel circuit and a driving method are provided. In the pixel circuit, a driving transistor has a driving terminal and a first terminal coupled to a first system voltage. The initialization circuit adjusts voltage levels of an input terminal and the driving terminal according to a previous-stage gate driving signal. A data writing circuit provides a data voltage to the input terminal according to a gate driving signal. A voltage compensation circuit adjusts the voltage level of the driving terminal according to a compensation control signal. A light emitting element has a cathode terminal and an anode terminal coupled to a second system voltage. A light emitting control circuit controls a light emitting state of the light emitting element according to a light emitting control signal. An enabling time of the compensation control signal is between a falling edge of the previous-stage gate driving signal and a rising edge of the gate driving signal.

Description

Pixel circuit and its driving method

The present invention relates to a display device, and particularly relates to a pixel circuit and a driving method thereof.

In a display device, when the manufacturing process changes, the threshold voltage of the driving transistor in the pixel circuit is often prone to drift, causing unexpected changes in the current flowing through the light-emitting element, which in turn causes the display panel The brightness of the light is unstable to affect the quality of the display picture.

Regarding the compensation technology of the threshold voltage of the driving transistor, the conventional pixel circuit usually starts to compensate the threshold voltage of the driving transistor during the period when the gate driving signal is in the enabled state. However, when the display device is operating at a high resolution (or high frequency), the enable time of the gate drive signal is quite limited, resulting in the compensation time of the threshold voltage of the pixel circuit being too short, which in turn makes the pixel circuit compensation The effect cannot be optimized. Therefore, how to improve the impact of the threshold voltage on the quality of the display image will be an important issue for those skilled in the art.

The present invention provides a pixel circuit and a driving method thereof, which can increase the compensation time for the threshold voltage of the driving transistor by adjusting the enable time of the compensation control signal, thereby effectively improving the quality of the display picture.

The pixel circuit of the present invention includes a driving transistor, an initialization circuit, a data writing circuit, a voltage compensation circuit, a light-emitting element, and a first light-emitting control circuit. The driving transistor has a driving terminal and a first terminal coupled to the first system voltage. The initialization circuit is coupled to the input terminal and the drive terminal, and adjusts the voltage levels of the input terminal and the drive terminal according to the previous gate drive signal. The data writing circuit is coupled to the input terminal, and provides a data voltage to the input terminal according to the gate drive signal. The voltage compensation circuit is coupled to the input terminal and the driving terminal, and adjusts the voltage level of the driving terminal according to the compensation control signal. The light-emitting element has a cathode terminal and an anode terminal coupled to the second system voltage. The first light-emitting control circuit is coupled to the cathode end of the light-emitting element, the voltage compensation circuit, and the second end of the driving transistor, and controls the light-emitting state of the light-emitting element according to the light-emitting control signal, wherein the activation time of the compensation control signal is in the previous stage Between the falling edge of the gate drive signal and the rising edge of the gate drive signal.

The driving method of the pixel circuit of the present invention includes: providing a driving transistor having a driving end, a first end, and a second end; providing an initialization circuit to adjust the voltage levels of the input end and the driving end according to the previous gate driving signal; Provide a data writing circuit to provide a data voltage to the input terminal according to the gate drive signal; provide a voltage compensation circuit to adjust the voltage level of the drive terminal according to the compensation control signal; provide a light-emitting element with a cathode terminal and an anode terminal; and provide a A light emitting control circuit controls the light emitting state of the light emitting element according to the light emitting control signal, wherein the enable time of the compensation control signal is between the falling edge of the previous gate drive signal and the rising edge of the gate drive signal.

The pixel circuit of the present invention includes a driving transistor, an initialization circuit, a data writing circuit, a voltage compensation circuit, a light-emitting element, and a light-emitting control circuit. The driving transistor has a driving terminal and a first terminal coupled to the first system voltage. The initialization circuit is coupled to the input terminal and the driving terminal for adjusting the voltage levels of the input terminal and the driving terminal based on the reference voltage and the gate driving signal and the previous gate driving signal. The data writing circuit is coupled to the input terminal, and provides a data voltage to the input terminal according to the gate drive signal. The voltage compensation circuit is coupled to the initialization circuit, and the voltage compensation circuit is used for adjusting the voltage level of the driving terminal according to the gate driving signal and the previous gate driving signal in the compensation stage. The light-emitting element has a cathode terminal and an anode terminal coupled to the second system voltage. The light-emitting control circuit is coupled to the cathode terminal of the light-emitting element, the voltage compensation circuit, and the second terminal of the driving transistor, and controls the light-emitting state of the light-emitting element according to the control signal. The compensation phase is between the falling edge of the previous gate drive signal and Between the rising edges of the gate drive signal.

The driving method of the pixel circuit of the present invention includes: providing a driving transistor having a driving terminal, a first terminal, and a second terminal; Adjust the voltage levels of the input terminal and the drive terminal; provide a data writing circuit to provide the data voltage to the input terminal according to the gate drive signal; provide a voltage compensation circuit to according to the gate drive signal and the previous gate drive signal in the compensation stage Adjust the voltage level of the driving terminal; provide a light-emitting element with a cathode terminal and an anode terminal; and provide a light-emitting control circuit to control the light-emitting state of the light-emitting element according to the control signal, wherein the compensation phase is between the falling edge of the previous gate drive signal and Between the rising edges of the gate drive signal.

Based on the above, the pixel circuits of the embodiments of the present invention can set the enable time of the compensation control signal to be between the falling edge of the previous-stage gate drive signal and the rising edge of the gate drive signal as a countermeasure. Compensation time for compensating the critical voltage of driving transistor. In this way, compared to the conventional pixel circuit which can only compensate for the threshold voltage of the driving transistor during the limited enable period of the gate drive signal, the pixel circuit of the present invention can compensate by lengthening The enabling time of the control signal is used to increase the compensation time for the threshold voltage of the driving transistor, thereby effectively improving the quality of the display image.

The term "coupling (or connection)" used in the full text of the specification of this case (including the scope of the patent application) can refer to any direct or indirect connection means. For example, if the text describes that the first device is coupled (or connected) to the second device, it should be interpreted as that the first device can be directly connected to the second device, or the first device can be connected through other devices or some This kind of connection means is indirectly connected to the second device. In addition, wherever possible, elements/components/steps with the same reference numbers in the drawings and embodiments represent the same or similar parts. Elements/components/steps that use the same reference numerals or use the same terms in different embodiments may refer to related descriptions.

FIG. 1 is a schematic diagram of a pixel circuit 100 according to an embodiment of the invention. 1, the pixel circuit 100 includes a driving transistor TD, an initialization circuit 110, a voltage compensation circuit 120, a data writing circuit 130, a light emitting control circuit 140, and a light emitting element EL. The anode terminal of the light-emitting element EL is coupled to the system voltage VDD, and the cathode terminal of the light-emitting element EL is coupled to the light emission control circuit 140. The light-emitting element EL can be correspondingly lit according to the conduction current ID. Wherein, the light-emitting element EL of this embodiment may be, for example, an organic light emitting diode (OLED), a light emitting diode (LED) or other light-emitting elements, and the present invention is not particularly limited.

The first terminal (that is, the source terminal) of the driving transistor TD is coupled to the system voltage VSS, and the second terminal (that is, the drain terminal) of the driving transistor TD is coupled to the light-emitting control circuit 140, and the driving transistor TD The driving terminal PD (that is, the gate terminal) is coupled to the voltage compensation circuit 120. Wherein, the system voltage VDD in this embodiment may be a system high voltage, and the system voltage VSS may be a system low voltage, and the voltage value of the system voltage VDD may be greater than the voltage value of the system voltage VSS.

The initialization circuit 110 is coupled to the input terminal PIN and the driving terminal PD. The initialization circuit 110 can be used to adjust the voltage levels of the input terminal PN and the driving terminal PD according to the previous gate drive signal SN-m. The voltage compensation circuit 120 is coupled to the input terminal PIN and the driving terminal PD. The voltage compensation circuit 120 can adjust the voltage level of the driving terminal PD according to the voltage on the input terminal PIN and/or the compensation control signal RN.

On the other hand, the data writing circuit 130 is coupled to the input terminal PIN. The data writing circuit 130 can be used to provide the data voltage VDATA to the input terminal PIN according to the gate driving signal SN. The light emitting control circuit 140 is coupled to the cathode terminal of the light emitting element EL, the voltage compensation circuit 120 and the second terminal of the driving transistor TD. The light emitting control circuit 140 can control the light emitting state of the light emitting element EL according to the light emitting control signal EM.

In particular, in this embodiment, the gate drive signal SN, the previous gate drive signal SN-m, the compensation control signal RN, and the light emission control signal EM can be generated by a control signal generator (not shown). produce. Wherein, the control signal generator (not shown) can be constructed by three groups of gate-driver-on-array (Gate-Driver-on-Array, GOA) circuits. In other words, since this embodiment can control the pixel circuit 100 through only three sets of GOA circuits, the overall area can be effectively saved.

In addition, in this embodiment, the gate drive signal SN may be an Nth stage gate drive signal generated by a GOA circuit (not shown), and the previous stage gate drive signal SN-m may be a GOA circuit (Not shown) The generated Nm-th gate drive signal. Wherein, the aforementioned N and m can be positive integers greater than 1, and can be determined according to the design requirements of the pixel circuit 100, and the present invention is not particularly limited.

Regarding the operation of the pixel circuit 100, specifically, when the pixel circuit 100 is operated in the compensation phase of a pixel period, the voltage compensation circuit 120 can be controlled according to the voltage on the input terminal PIN and/or the compensation that is pulled up. The signal RN adjusts the voltage level of the driving terminal PD of the driving transistor TD, so as to compensate the threshold voltage of the driving transistor TD.

It is worth mentioning that the pixel circuit 100 can improve the compensation effect of the threshold voltage of the driving transistor TD by adjusting the front-stage gate driving signal SN-m and the compensation control signal RN. For example, in this embodiment, the enable time of the compensation control signal RN received by the voltage compensation circuit 120 can be set to be between the falling edge of the previous gate drive signal SN-m and the gate drive signal SN. Between rising edges.

Furthermore, the pixel circuit 100 can switch from the enabled state to the disabled state (for example, from a high voltage level to After the low voltage level), continue to set the compensation control signal RN to the enabled state (for example, the high voltage level), until the gate drive signal SN (that is, the Nth-level gate drive signal) wants to go from the disabled state The transition to the enabled state (for example, the transition from a low voltage level to a high voltage level).

That is, in this embodiment, the time interval between the falling edge of the previous gate drive signal SN-m and the rising edge of the gate drive signal SN can be used as the compensation time for compensating the threshold voltage of the drive transistor TD. Therefore, compared to the conventional pixel circuit which can only compensate for the threshold voltage of the driving transistor during the limited enable period of the gate driving signal, the pixel circuit 100 of this embodiment can compensate by lengthening The enabling time of the control signal RN is used to increase the compensation time for the threshold voltage of the driving transistor TD, thereby effectively improving the quality of the display picture.

2A to 2G are circuit diagrams of pixel circuits 200-800 according to different embodiments of the present invention according to the pixel circuit 100 of the embodiment of FIG. 1. 2A, the pixel circuit 200 includes a driving transistor TD, an initialization circuit 210, a voltage compensation circuit 220, a data writing circuit 230, a light emitting control circuit 240, and a light emitting element EL.

The initialization circuit 210 includes transistors T1 to T2. The first terminal (that is, the source terminal) of the transistor T1 is coupled to the input terminal PIN, and the second terminal (that is, the drain terminal) and the control terminal (that is, the gate terminal) of the transistor T1 can receive the previous stage together Gate drive signal SN-m. Among them, the transistor T1 can be a diode connection to form a diode. The first terminal (that is, the source terminal) of the transistor T2 is coupled to the driving terminal PD, and the second terminal (that is, the drain terminal) of the transistor T2 is coupled to the system voltage VDD and the anode terminal of the light emitting element EL. The control terminal (that is, the gate terminal) of the crystal T2 can receive the previous gate drive signal SN-m.

The voltage compensation circuit 220 includes transistors T3 to T4 and a capacitor C1. The first terminal (that is, the source terminal) of the transistor T3 is coupled to the driving terminal PD, and the second terminal (that is, the drain terminal) of the transistor T3 is coupled to the second terminal of the driving transistor TD, and the transistor T3 The control terminal (that is, the gate terminal) receives the compensation control signal RN. The first terminal (that is, the source terminal) of the transistor T4 is coupled to the reference voltage VREF, the second terminal (that is, the drain terminal) of the transistor T4 is coupled to the input terminal PIN, and the control terminal (also That is, the gate terminal) receives the compensation control signal RN. The first terminal of the capacitor C1 is coupled to the input terminal PIN, and the second terminal of the capacitor C1 is coupled to the driving terminal PD.

The data writing circuit 230 includes a transistor T5. The first terminal (that is, the source terminal) of the transistor T5 is coupled to the input terminal PIN, the second terminal (that is, the drain terminal) of the transistor T5 receives the data voltage VDATA, and the control terminal (that is, Gate terminal) receives the gate drive signal SN.

The light emission control circuit 240 includes a transistor T6. The first terminal (that is, the source terminal) of the transistor T6 is coupled to the second terminal of the driving transistor TD, and the second terminal (that is, the drain terminal) of the transistor T6 is coupled to the cathode terminal of the light emitting element EL, The control terminal (that is, the gate terminal) of the transistor T6 receives the light emission control signal EM.

The first terminal of the driving transistor TD is coupled to the system voltage VSS, the second terminal of the driving transistor TD is coupled to the first terminal of the transistor T6, and the driving terminal PD of the driving transistor TD is coupled to the second terminal of the capacitor C1. end.

3 is a schematic diagram of waveforms of an embodiment of the pixel circuits 200-800 of FIGS. 2A to 2G according to the present invention. For details of the operation of the pixel circuit 200, please refer to FIG. 2A and FIG. 3 at the same time. In detail, when the pixel circuit 200 is operating in the reset phase TR, the previous gate drive signal SN-m can be set to an enabled state (for example, a high voltage level), and the light emission control signal EM and the gate Both the driving signal SN and the compensation control signal RN can be set to a disabled state (for example, a low voltage level).

In this case, the transistor T1 of the initialization circuit 210 can provide the gate voltage VGH to the input terminal PIN according to the previous gate drive signal SN-m that is pulled high, and the transistor T2 of the initialization circuit 210 can be The front-stage gate drive signal SN-m is pulled high to provide the system voltage VDD (that is, the system high voltage) to the drive terminal PD. In this way, the initialization circuit 210 can pull up the voltage levels of the input terminal PIN and the driving terminal PD to reset the input terminal PIN and the driving terminal PD, and enable the driving transistor TD to be turned on, thereby ensuring subsequent compensation The operation can proceed smoothly.

On the other hand, when the pixel circuit 200 is operating in the compensation stage TC, the compensation control signal RN can be set to an enabled state (for example, a high voltage level), and the light emission control signal EM and the previous-stage gate drive signal SN- Both m and the gate drive signal SN can be set to a disabled state (for example, a low voltage level).

In this case, the voltage compensation circuit 220 can provide the reference voltage VREF to the input terminal PIN according to the pulled-up compensation control signal RN, and adjust the voltage level of the driving terminal PD to the voltage value of the system voltage VSS and the driving transistor The sum of the voltage values of the threshold voltage VTH of the TD (that is, VSS+VTH (where VSS is the voltage value of the system voltage VSS; VTH is the voltage value of the threshold voltage of the driving transistor TD)).

Then, when the pixel circuit 200 is operating in the data writing phase TDA, the gate drive signal SN can be set to an enabled state (for example, a high voltage level), and the light emission control signal EM and the previous gate drive signal SN Both -m and the compensation control signal RN can be set to a disabled state (for example, a low voltage level).

V的電壓值，其中，

V為輸入端PIN操作在重置階段TR以及補償階段TC之間時的電壓值的變化量（亦即，VDATA-VREF（其中，VDATA為資料電壓VDATA的電壓值；VREF為參考電壓VREF的電壓值））。 In this case, the data writing circuit 230 can provide the data voltage VDATA to the input terminal PIN according to the gate driving signal SN that is pulled high. At the same time, through the coupling effect of the capacitor C1, the voltage compensation circuit 220 can further increase the voltage level of the driving terminal PD to VSS+VTH+

The voltage value of V, where,

V is the change in the voltage value of the input terminal PIN between the reset phase TR and the compensation phase TC (that is, VDATA-VREF (where VDATA is the voltage value of the data voltage VDATA; VREF is the voltage value of the reference voltage VREF value)).

On the other hand, when the pixel circuit 200 is operating in the light-emitting phase TE, the light-emitting control signal EM can be set to an enabled state (for example, a high voltage level), and the previous-stage gate drive signal SN-m, gate drive Both the signal SN and the compensation control signal RN can be set to a disabled state (for example, a low voltage level).

Under this operation, the voltage level of the driving terminal PD of the driving transistor TD can be maintained at the voltage level during the data writing phase TDA (ie, VSS+VTH+(VDATA-VREF)). Therefore, when the pixel circuit 200 is operated in the light-emitting phase TE and the driving transistor TD is operated in the saturation region, the driving transistor TD can generate the on-current ID to drive the light-emitting element EL. At this time, the on-current ID flowing through the light-emitting element EL can be as shown in the following equation: ID=K

Among them, the above ID is the current value of the conduction current ID; K is the process parameter of the driving transistor TD; VSS is the voltage value of the system voltage VSS; VTH is the voltage value of the threshold voltage VTH of the driving transistor TD; VDATA is the data voltage The voltage value of VDATA; VREF is the voltage value of the reference voltage VREF.

In other words, in the light-emitting phase TE, the pixel circuit 200 can effectively eliminate the deviation of the threshold voltage of the driving transistor TD caused by the process variation. In addition, in this embodiment, since the enable time of the compensation control signal RN is between the falling edge of the previous gate drive signal SN-m and the rising edge of the gate drive signal SN, the pixel The circuit 200 can compensate the threshold voltage VTH of the driving transistor TD in a sufficiently long compensation stage TC (or compensation time), so as to improve the compensation effect of the pixel circuit 200.

2B, the pixel circuit 300 includes a driving transistor TD, an initialization circuit 310, a voltage compensation circuit 320, a data writing circuit 330, a light emitting control circuit 340, and a light emitting element EL. The pixel circuit 300 is substantially the same or similar to the pixel circuit 200, and the same or similar components are given the same or similar reference numerals. Different from the embodiment in FIG. 2A, in the initialization circuit 310, the first terminal of the transistor T2 is coupled to the driving terminal PD, and the second terminal and the control terminal of the transistor T2 can receive the previous gate driving signal SN together. -m.

In other words, in the embodiment shown in FIG. 2B, when the pixel circuit 300 is operating in the reset phase TR (as shown in FIG. 3), the transistor T2 of the initialization circuit 310 is based on the previous-stage gate that is pulled high. The driving signal SN-m provides the gate voltage VGH to the driving terminal PD to reset the driving terminal PD.

Among them, the driving transistor TD, the initialization circuit 310, the voltage compensation circuit 320, the data writing circuit 330, the light emitting control circuit 340, and the light emitting element EL shown in FIG. 2B operate in the reset stage TR, the compensation stage TC, and the data writing stage. The implementation details of the TDA and the light-emitting phase TE can be deduced by analogy with reference to the relevant description of FIG. 2A, and therefore will not be repeated.

It is worth mentioning that, in the embodiment of FIG. 2A and FIG. 2B, the pixels 200 and 300 only need 7 transistors to be formed, so the pixels 200 and 300 can have the advantages of saving area and cost.

2C, the pixel circuit 400 includes a driving transistor TD, an initialization circuit 410, a voltage compensation circuit 420, a data writing circuit 430, a light emitting control circuit 440, and a light emitting element EL. The pixel circuit 400 is substantially the same or similar to the pixel circuits 200 and 300, and the same or similar components are given the same or similar reference numerals. Different from the embodiment in FIG. 2A and FIG. 2B, the pixel circuit 400 further includes a leakage current compensation circuit 450 and a light emission control circuit 460.

The light emission control circuit 460 includes a transistor T8. The first terminal (that is, the source terminal) of the transistor T8 is coupled to the system voltage VSS, and the second terminal (that is, the drain terminal) of the transistor T8 is coupled to the first terminal of the driving transistor TD, and the transistor T8 The control terminal (that is, the gate terminal) receives the emission control signal EM.

The leakage current compensation circuit 450 includes a transistor T7. The first terminal (that is, the source terminal) of the transistor T7 is coupled to the first terminal of the transistor T8, and the second terminal (that is, the drain terminal) of the transistor T7 is coupled to the second terminal of the transistor T8, The control terminal (that is, the gate terminal) of the transistor T7 receives the compensation control signal RN.

For details of the operation of the pixel circuit 400, please refer to FIG. 2C and FIG. 3 at the same time. In detail, when the pixel circuit 400 is operating in the reset stage TR, the transistor T1 of the initialization circuit 410 can provide the gate voltage VGH to the input terminal PIN according to the previous-stage gate drive signal SN-m that is pulled up. , And the transistor T2 of the initialization circuit 410 can provide the gate voltage VGH to the driving terminal PD according to the pulled-up previous gate driving signal SN-m. In this way, the initialization circuit 410 can pull up the voltage levels of the input terminal PIN and the driving terminal PD to reset the input terminal PIN and the driving terminal PD, and enable the driving transistor TD to be turned on to ensure subsequent compensation The operation can proceed smoothly.

On the other hand, when the pixel circuit 400 operates in the compensation stage TC, the voltage compensation circuit 420 can provide the reference voltage VREF to the input terminal PIN according to the pulled-up compensation control signal RN, and adjust the voltage level of the driving terminal PD It is the sum of the voltage value of the system voltage VSS and the voltage value of the threshold voltage VTH of the driving transistor TD (that is, VSS+VTH).

It should be noted that, in order to prevent the pixel circuit 400 from causing excessive leakage current in the driving transistor TD during the long compensation time, therefore, when the pixel circuit 400 operates in the compensation phase TC, the leakage current compensation circuit 450 The transistor T7 can be turned on according to the pulled-up compensation control signal RN, thereby forming a leakage current drain path. Thereby, the leakage current compensation circuit 450 can discharge the leakage current generated by the driving transistor TD to the system voltage VSS (that is, the system low voltage) through the leakage current discharge path during the compensation phase TC. In this way, the pixel circuit 400 of this embodiment can effectively suppress the instantaneous leakage current generated by the driving transistor TD.

In particular, in order to avoid excessive leakage current, in the design of the leakage current compensation circuit 450, the aspect ratio of the transistor T7 can be designed to be smaller than the aspect ratio of the transistor T8, but the present invention is not limited to this.

V的電壓值，其中，

V為輸入端PIN操作在重置階段TR以及補償階段TC之間時的電壓值的變化量（亦即，VDATA-VREF）。 Then, when the pixel circuit 400 operates in the data writing phase TDA, the data writing circuit 430 can provide the data voltage VDATA to the input terminal PIN according to the gate drive signal SN that is pulled high. At the same time, through the coupling effect of the capacitor C1, the voltage compensation circuit 420 can further increase the voltage level of the driving terminal PD to VSS+VTH+

The voltage value of V, where,

V is the amount of change (ie, VDATA-VREF) of the voltage value when the input terminal PIN is operated between the reset phase TR and the compensation phase TC.

On the other hand, when the pixel circuit 400 operates in the light-emitting phase TE, the voltage level of the driving terminal PD of the driving transistor TD can be maintained at the voltage level during the data writing phase TDA (ie, VSS+VTH+(VDATA -VREF)). Therefore, when the pixel circuit 400 is operated in the light-emitting phase TE and the driving transistor TD is operated in the saturation region, the driving transistor TD can generate the conduction current ID to drive the light-emitting element EL. At this time, the on-current ID flowing through the light-emitting element EL can be as shown in the following equation: ID=K

In other words, in the light-emitting phase TE, the pixel circuit 400 can also effectively eliminate the deviation of the threshold voltage of the driving transistor TD caused by the process variation. In addition, the pixel circuit 400 can also compensate the threshold voltage VTH of the driving transistor TD in a sufficiently long compensation period TC (or compensation time), so as to improve the compensation effect of the pixel circuit 400.

2D, the pixel circuit 500 includes a driving transistor TD, an initialization circuit 510, a voltage compensation circuit 520, a data writing circuit 530, light emission control circuits 540, 560, a leakage current compensation circuit 550, and a light emitting element EL. The pixel circuit 500 is substantially the same or similar to the pixel circuit 400, wherein the same or similar components are given the same or similar reference numerals. Different from the embodiment in FIG. 2C, in the voltage compensation circuit 520, the first end of the transistor T4 is coupled to the second end of the transistor T7.

Please refer to FIG. 2D and FIG. 3 at the same time. The implementation details of the pixel circuit 500 during the reset stage TR can be deduced with reference to the related description of FIG. 2C, so it will not be repeated.

On the other hand, when the pixel circuit 500 is operating in the compensation phase TC, the transistors T3, T4, and T7 can be turned on according to the compensation control signal RN that is pulled high. In this case, the transistors T4 and T7 can provide the system voltage VSS to the input terminal PIN through the conduction path. In addition, the voltage compensation circuit 520 and the leakage current compensation circuit 550 can adjust the voltage level of the driving terminal PD to the voltage value of the system voltage VSS and the voltage of the threshold voltage VTH of the driving transistor TD according to the pulled-up compensation control signal RN. The sum of the values (ie, VSS+VTH).

Similar to the embodiment in FIG. 2C, in this embodiment, the pixel circuit 500 can also pass through the leakage current catharsis path formed by the leakage current compensation circuit 550 during the compensation phase TC, so as to reduce the instant generated by the driving transistor TD. The leakage current is discharged to the system voltage VSS (that is, the system low voltage).

Then, when the pixel circuit 500 operates in the data writing phase TDA, the transistor T5 can be turned on according to the gate drive signal SN that is pulled high. In this case, the data writing circuit 530 can provide the data voltage VDATA to the input terminal PIN according to the gate drive signal SN that is pulled high. At the same time, through the coupling effect of the capacitor C1, the voltage compensation circuit 520 can further increase the voltage level of the driving terminal PD to the voltage value of VDATA+VTH.

On the other hand, when the pixel circuit 500 operates in the light-emitting phase TE, the transistors T6 and T8 can be turned on according to the light-emitting control signal EM that is pulled high. Under this operation, the voltage level of the driving terminal PD of the driving transistor TD can be maintained at the voltage level during the data writing phase TDA (ie, VDATA+VTH). Therefore, when the pixel circuit 500 is operated in the light-emitting phase TE and the driving transistor TD is operated in the saturation region, the driving transistor TD can generate the on-current ID to drive the light-emitting element EL. At this time, the on-current ID flowing through the light-emitting element EL can be as shown in the following equation: ID=K

In other words, in the light-emitting phase TE, the pixel circuit 500 can also effectively eliminate the threshold voltage deviation of the driving transistor TD caused by the process variation. In addition, the pixel circuit 500 can also compensate the threshold voltage VTH of the driving transistor TD in a sufficiently long compensation period TC (or compensation time), so as to improve the compensation effect of the pixel circuit 500.

2E, the pixel circuit 600 includes a driving transistor TD, an initialization circuit 610, a voltage compensation circuit 620, a data writing circuit 630, light emission control circuits 640, 660, a leakage current compensation circuit 650, and a light emitting element EL. The pixel circuit 600 is substantially the same or similar to the pixel circuit 500, in which the same or similar components use the same or similar reference numerals. Different from the embodiment in FIG. 2D, in the initialization circuit 610, the first terminal of the transistor T2 is coupled to the driving terminal PD, and the second terminal of the transistor T2 can be coupled to the system voltage VDD, and the control terminal of the transistor T2 Receive the previous gate drive signal SN-m.

In other words, in the embodiment shown in FIG. 2E, when the pixel circuit 600 operates in the reset phase TR (as shown in FIG. 3), the transistor T2 of the initialization circuit 610 is based on the previous-stage gate that is pulled high. The driving signal SN-m provides the system voltage VDD (that is, the system high voltage) to the driving terminal PD to reset the driving terminal PD.

Among them, the driving transistor TD, the initialization circuit 610, the voltage compensation circuit 620, the data writing circuit 630, the light emission control circuits 640, 660, the leakage current compensation circuit 650, and the light emitting element EL shown in FIG. 2E operate in the reset phase TR, The implementation details of the compensation phase TC, the data writing phase TDA, and the light-emitting phase TE can be deduced by analogy with reference to the relevant description in FIG. 2D, and therefore will not be repeated.

2F, the pixel circuit 700 includes a driving transistor TD, an initialization circuit 710, a voltage compensation circuit 720, a data writing circuit 730, light emission control circuits 740, 760, a leakage current compensation circuit 750, and a light emitting element EL. The same or similar elements use the same or similar reference numerals. Different from the embodiment in FIG. 2D, in the leakage current compensation circuit 750, the first terminal of the transistor T7 is coupled to the input terminal PIN, the second terminal of the transistor T7 is coupled to the reference voltage VREF, and the control of the transistor T7 The terminal receives the compensation control signal RN.

Furthermore, in the embodiment shown in FIG. 2F, when the pixel circuit 700 is operating in the compensation phase TC (as shown in FIG. 3), the transistors T3, T4, and T7 can be pulled up according to the compensation control signal RN And it is turned on. In this case, the leakage current compensation circuit 750 can provide the reference voltage VREF to the input terminal PIN according to the pulled-up compensation control signal RN, and the voltage compensation circuit 720 can drive the driving terminal PD according to the pulled-up compensation control signal RN. The voltage level of is adjusted to the sum of the voltage value of the reference voltage VREF and the voltage value of the threshold voltage VTH of the driving transistor TD (ie, VREF+VTH).

Similar to the embodiment in FIG. 2D, the pixel circuit 700 can pass through the leakage current catharsis path formed by the transistor T7 of the leakage current compensation circuit 750 and the transistor T4 of the voltage compensation circuit 720 during the compensation stage TC, so as to transfer the driving power. The instantaneous leakage current generated by the crystal TD is discharged to the reference voltage VREF.

Among them, the driving transistor TD, the initialization circuit 710, the voltage compensation circuit 720, the data writing circuit 730, the light emission control circuits 740, 760, the leakage current compensation circuit 750, and the light emitting element EL shown in FIG. 2F operate in the reset phase TR, The implementation details of the compensation phase TC, the data writing phase TDA, and the light-emitting phase TE can be deduced by analogy with reference to the relevant description in FIG. 2D, and therefore will not be repeated.

2G, the pixel circuit 800 includes a driving transistor TD, an initialization circuit 810, a voltage compensation circuit 820, a data writing circuit 830, light emission control circuits 840, 860, a leakage current compensation circuit 850, and a light emitting element EL. The same or similar elements use the same or similar reference numerals. Different from the embodiment in FIG. 2C, in the initialization circuit 810, the first terminal of the transistor T2 is coupled to the driving terminal PD, the second terminal of the transistor T2 is coupled to the system voltage VDD, and the control terminal of the transistor T2 receives The front gate drive signal SN-m.

In other words, in the embodiment shown in FIG. 2G, when the pixel circuit 800 is operating in the reset phase TR (as shown in FIG. 3), the transistor T2 of the initialization circuit 810 is based on the previous-stage gate that is pulled high. The driving signal SN-m provides the system voltage VDD (that is, the system high voltage) to the driving terminal PD to reset the driving terminal PD.

Among them, the driving transistor TD, the initialization circuit 810, the voltage compensation circuit 820, the data writing circuit 830, the light emission control circuits 840, 860, the leakage current compensation circuit 850, and the light emitting element EL shown in FIG. 2G operate in the reset phase TR, The implementation details of the compensation phase TC, the data writing phase TDA, and the light-emitting phase TE can be deduced by analogy with reference to the relevant description of FIG. 2C, and therefore will not be repeated.

It should be noted that for many of the above-mentioned embodiments in FIG. 1, FIG. 2A to FIG. 2G, and FIG. The signal RN can be set to an enabled state (for example, a high voltage level) in the current frame (Frame). That is, each pixel circuit can compensate the threshold voltage VTH of the driving transistor TD in the current frame.

On the other hand, please refer to FIG. 4, which is a waveform diagram of another embodiment of the pixel circuit of FIGS. 2A to 2G according to the present invention. Under some other design requirements, each pixel circuit can also pre-enable the compensation control signal RN in the previous frame, so that the pixel circuit can start the threshold voltage VTH of the driving transistor TD in the previous frame in advance. Perform compensation operations. In this way, the pixel circuit of this embodiment can further extend the time interval of the compensation stage TC, so as to improve the influence of the threshold voltage on the quality of the display image.

FIG. 5 is a schematic diagram of a pixel circuit 900 according to another embodiment of the invention. 5, the pixel circuit 900 includes a driving transistor TD, an initialization circuit 910, a voltage compensation circuit 920, a data writing circuit 930, a light emitting control circuit 940, and a light emitting element EL. The anode end of the light emitting element EL is coupled to the system voltage VDD, and the cathode end of the light emitting element EL is coupled to the light emission control circuit 940. The light-emitting element EL can be correspondingly lit according to the conduction current ID.

The first terminal (that is, the source terminal) of the driving transistor TD is coupled to the system voltage VSS, and the second terminal (that is, the drain terminal) of the driving transistor TD is coupled to the light-emitting control circuit 940, and the driving transistor TD The driving terminal PD (that is, the gate terminal) is coupled to the initialization circuit 910.

The initialization circuit 910 is coupled to the input terminal PIN and the driving terminal PD. The initialization circuit 910 can be used to adjust the voltage levels of the input terminal PN and the driving terminal PD based on the reference voltage VREF (or the system voltage VDD) and the gate drive signal SN and the previous gate drive signal SN-m. The voltage compensation circuit 920 is coupled to the initialization circuit 920. The voltage compensation circuit 920 can be used to adjust the voltage level of the driving terminal PD according to the gate driving signal SN and the previous gate driving signal SN-m in the compensation phase.

On the other hand, the data writing circuit 930 is coupled to the input terminal PIN. The data writing circuit 930 can be used to provide the data voltage VDATA to the input terminal PIN according to the gate driving signal SN. The light emitting control circuit 940 is coupled to the cathode terminal of the light emitting element EL, the voltage compensation circuit 920 and the second terminal of the driving transistor TD. The light emitting control circuit 940 can control the light emitting state of the light emitting element EL according to the control signal CS.

It is worth mentioning that the control signal CS in this embodiment can be, for example, a gate drive signal SN, a light emission control signal EM, or a subsequent gate drive signal SN+i. For example, the control signal CS may be generated by a control signal generator (not shown). Wherein, the control signal generator (not shown) may be constructed by one or more sets of GOA circuits.

Regarding the operation of the pixel circuit 900, specifically, when the pixel circuit 900 is operated in the compensation stage of a pixel period, the voltage compensation circuit 920 can be driven by the gate drive signal SN and the previous gate drive. The signal SN-m is used to adjust the voltage level of the driving terminal PD of the driving transistor TD, so as to compensate the threshold voltage of the driving transistor TD.

Furthermore, in this embodiment, the compensation stage can be set to be between the falling edge of the previous gate drive signal SN-m and the rising edge of the gate drive signal SN. For example, the pixel circuit 900 may continue to execute the compensation driving circuit after the previous gate drive signal SN-m is converted from the enabled state to the disabled state (for example, from a high voltage level to a low voltage level). The threshold voltage of the crystal TD is compensated until the gate drive signal SN is about to switch from the disabled state to the enabled state (for example, from a low voltage level to a high voltage level).

That is, in this embodiment, the time interval between the falling edge of the previous gate drive signal SN-m and the rising edge of the gate drive signal SN can be used as the compensation time for compensating the threshold voltage of the drive transistor TD. Therefore, compared to the conventional pixel circuit which can only compensate for the threshold voltage of the driving transistor during the limited enable period of the gate drive signal, the pixel circuit 900 of this embodiment can compensate by lengthening The working time of the stage is to increase the compensation time for the threshold voltage of the driving transistor TD, and thereby effectively improve the quality of the display picture.

6A to 6B are circuit diagrams showing pixel circuits 1000 and 1100 of different embodiments of the present invention according to the pixel circuit of the embodiment of FIG. 5. 6A, the pixel circuit 1000 includes a driving transistor TD, an initialization circuit 1010, a voltage compensation circuit 1020, a data writing circuit 1030, a light emitting control circuit 1040, and a light emitting element EL.

The initialization circuit 1010 includes transistors T1 to T4 and a capacitor C1. The second terminal (that is, the drain terminal) and the control terminal (that is, the gate terminal) of the transistor T1 can jointly receive the previous-stage gate drive signal SN-m. Among them, the transistor T1 can be a diode configuration to form a diode. The first terminal (that is, the source terminal) of the transistor T2 is coupled to the first terminal (that is, the source terminal) of the transistor T1, and the second terminal (that is, the drain terminal) of the transistor T2 receives the front gate The gate drive signal SN-m, and the control terminal (ie, the gate terminal) of the transistor T2 receives the gate drive signal SN.

The first terminal (that is, the source terminal) of the transistor T3 is coupled to the input terminal PIN, the second terminal (that is, the drain terminal) of the transistor T3 is coupled to the reference voltage VREF, and the control terminal (also That is, the gate terminal) is coupled to the first terminal of the transistor T2. The first terminal (that is, the source terminal) of the transistor T4 is coupled to the driving terminal PD, and the second terminal (that is, the drain terminal) and the control terminal (that is, the gate terminal) of the transistor T4 jointly receive the front gate Polar drive signal SN-m. Among them, the transistor T4 can be a diode configuration to form a diode. The first terminal of the capacitor C1 is coupled to the input terminal PIN, and the second terminal of the capacitor C1 is coupled to the driving terminal PD.

The voltage compensation circuit 1020 includes a transistor T5. The first terminal (that is, the source terminal) of the transistor T5 is coupled to the driving terminal PD, the second terminal (that is, the drain terminal) of the transistor T5 is coupled to the light-emitting control circuit 1040, and the control terminal ( That is, the gate terminal) is coupled to the first terminal of the transistor T2.

The data writing circuit 1030 includes a transistor T6. The first terminal (that is, the source terminal) of the transistor T6 is coupled to the input terminal PIN, the second terminal (that is, the drain terminal) of the transistor T6 receives the data voltage VDATA, and the control terminal (that is, Gate terminal) receives the gate drive signal SN.

The light emission control circuit 1040 includes a transistor T7. The first terminal (that is, the source terminal) of the transistor T7 is coupled to the second terminal of the transistor T5, and the second terminal (that is, the drain terminal) of the transistor T7 is coupled to the cathode terminal of the light emitting element EL, The control terminal (that is, the gate terminal) of the crystal T7 receives the gate drive signal SN.

The first terminal of the driving transistor TD is coupled to the system voltage VSS, the second terminal of the driving transistor TD is coupled to the first terminal of the transistor T7, and the driving terminal PD of the driving transistor TD is coupled to the second terminal of the capacitor C1. end.

FIG. 7 is a schematic diagram of waveforms of the pixel circuits 1000 and 1100 of FIGS. 6A to 6B according to the present invention. For details of the operation of the pixel circuit 1000, please refer to FIG. 6A and FIG. 7 at the same time. In detail, when the pixel circuit 1000 is operating in the reset phase TR, the previous gate drive signal SN-m can be set to an enabled state (for example, a high voltage level), and the gate drive signal SN can be set Set to disabled state (for example, low voltage level).

In this case, the transistor T1 of the initialization circuit 1010 can provide the gate high voltage VGH to the control terminals of the transistors T3 and T5 according to the pre-stage gate drive signal SN-m that is pulled high, so that the transistors T3 and T5 It is the conducting state. Then, the transistor T5 can provide the gate voltage VGH to the driving terminal PD through the conduction path. In addition, the transistor T3 can also provide the reference voltage VREF to the input terminal PIN through the conduction path. In this way, the initialization circuit 1010 can pull up the voltage levels of the input terminal PIN and the driving terminal PD to reset the input terminal PIN and the driving terminal PD, and enable the driving transistor TD to be turned on, thereby ensuring subsequent compensation The operation can proceed smoothly.

On the other hand, when the pixel circuit 1000 is operating in the compensation stage TC, the previous gate drive signal SN-m and the gate drive signal SN can both be set to a disabled state (for example, a low voltage level). In this case, the transistor T5 of the voltage compensation circuit 1020 maintains the voltage level of the control terminal at the voltage of the gate voltage VGH according to the previous gate drive signal SN-m and the gate drive signal SN that are pulled down. value. In addition, the transistor T5 adjusts the voltage level of the driving terminal PD to the sum of the voltage value of the system voltage VSS and the voltage value of the threshold voltage VTH of the driving transistor TD (ie, VSS+VTH) through the conduction path.

In addition, the transistor T3 can still maintain the voltage level of the input terminal PIN at the voltage value of the reference voltage VREF through the conduction path.

V的電壓值，其中，

V為輸入端PIN操作在重置階段TR以及補償階段TC之間時的電壓值的變化量（亦即，VDATA-VREF（其中，VDATA為資料電壓VDATA的電壓值；VREF為參考電壓VREF的電壓值））。 Then, when the pixel circuit 1000 operates in the light-emitting phase TE, the gate drive signal SN can be set to an enabled state (for example, a high voltage level), and the previous-stage gate drive signal SN-m can be set to be disabled Energy status (for example, low voltage level). In this case, the data writing circuit 1030 can provide the data voltage VDATA to the input terminal PIN according to the gate drive signal SN that is pulled high. At the same time, through the coupling effect of the capacitor C1, the initialization circuit 1010 can further increase the voltage level of the driving terminal PD to VSS+VTH+

The voltage value of V, where,

V is the change in the voltage value of the input terminal PIN between the reset stage TR and the compensation stage TC (that is, VDATA-VREF (where VDATA is the voltage value of the data voltage VDATA; VREF is the voltage value of the reference voltage VREF value)).

In addition, in the light-emitting phase TE, the transistor T7 of the light-emitting control circuit 1040 can be turned on according to the gate drive signal SN that is pulled up, and the driving transistor TD can be turned on according to the voltage on the driving terminal PD. The current ID is used to drive the light-emitting element EL. At this time, the on-current ID flowing through the light-emitting element EL can be as shown in the following equation: ID=K

In other words, in the light-emitting phase TE, the pixel circuit 1000 can simultaneously provide the data voltage VDATA to the input terminal PIN and light up the light-emitting element EL. In addition, the pixel circuit 1000 can also effectively eliminate the deviation of the threshold voltage of the driving transistor TD caused by the process variation. In addition, the pixel circuit 1000 can also perform a compensation action on the threshold voltage VTH of the driving transistor TD in a sufficiently long compensation stage TC (or compensation time), so as to improve the compensation effect of the pixel circuit 1000.

6B, the pixel circuit 1100 includes a driving transistor TD, an initialization circuit 1110, a voltage compensation circuit 1120, a data writing circuit 1130, a light emitting control circuit 1140, and a light emitting element EL. The pixel circuit 1100 is substantially the same or similar to the pixel circuit 1000, in which the same or similar components use the same or similar reference numerals. Different from the embodiment in FIG. 6A, in the initialization circuit 1110, the second terminal of the transistor T3 can be coupled to the system voltage VDD.

In other words, in the embodiment shown in FIG. 6B, when the pixel circuit 1100 is operating in the reset phase TR, the transistor T3 can provide the system voltage VDD to the input terminal PIN according to the voltage of its control terminal, so as to perform the operation on the input terminal PIN. Reset action.

Among them, the driving transistor TD, the initialization circuit 1110, the voltage compensation circuit 1120, the data writing circuit 1130, the light-emitting control circuit 1140, and the light-emitting element EL shown in FIG. 6B operate during the reset phase TR, the compensation phase TC, and the light-emitting phase TE. The implementation details of can be deduced by analogy with reference to the relevant description of FIG. 6A, so it will not be repeated.

It is worth mentioning that in the embodiments of FIGS. 6A and 6B, the pixel circuits 1000 and 1100 are only controlled by the previous gate drive signal SN-m and the gate drive signal SN. In other words, in this embodiment, the pixel circuits 1000 and 1100 can be controlled by only one set of GOA circuits, so the overall area can be effectively saved.

FIG. 8 is a circuit diagram of a pixel circuit 1200 according to a different embodiment of the present invention according to the pixel circuit of the embodiment of FIG. 5. 8, the pixel circuit 1200 includes a driving transistor TD, an initialization circuit 1210, a voltage compensation circuit 1220, a data writing circuit 1230, a light emitting control circuit 1240, and a light emitting element EL. The pixel circuit 1200 is substantially the same or similar to the pixel circuit 1000, wherein the same or similar components use the same or similar reference numerals.

Different from the embodiment of FIG. 6A, in the light emission control circuit 1240, the transistor T7 can be controlled by the light emission control signal EM. FIG. 9 is a schematic waveform diagram of the pixel circuit 1200 of FIG. 8 according to the present invention. 8 and 9 at the same time, when the pixel circuit 1200 is operating in the light-emitting phase TE, the light-emitting control circuit 1240 can generate a driving current ID according to the pulled-up light-emitting control signal EM, and light up the light through the driving current ID Element EL.

Among them, the driving transistor TD, the initialization circuit 1210, the voltage compensation circuit 1220, the data writing circuit 1230, the light emission control circuit 1240, and the light emitting element EL shown in FIG. 8 operate in the reset stage TR, the compensation stage TC, and the data writing stage. The implementation details of the TDA and the light-emitting phase TE can be deduced by analogy with reference to the relevant description of FIG. 6A, and therefore will not be repeated.

FIG. 10 is a pixel circuit according to the embodiment of FIG. 5 showing different implementations of the present invention The circuit diagram of the pixel circuit 1300 of the example. 10, the pixel circuit 1300 includes a driving transistor TD, an initialization circuit 1310, a voltage compensation circuit 1320, a data writing circuit 1330, a light emitting control circuit 1340, and a light emitting element EL. The pixel circuit 1300 is substantially the same or similar to the pixel circuit 1100, and the same or similar components are given the same or similar reference numerals.

Different from the embodiment in FIG. 6B, in the light emission control circuit 1340, the transistor T7 can be controlled by the subsequent gate drive signal SN+i. FIG. 11 is a schematic waveform diagram of the pixel circuit 1300 of FIG. 10 according to the present invention. 10 and 11 at the same time, when the pixel circuit 1300 is operating in the light-emitting phase TE, the light-emitting control circuit 1340 can generate a driving current ID according to the subsequent gate driving signal SN+i that is pulled high, and pass the driving current ID to light up the light-emitting element EL. Wherein, the aforementioned i is a positive integer greater than 1.

Among them, the driving transistor TD, the initialization circuit 1310, the voltage compensation circuit 1320, the data writing circuit 1330, the light emission control circuit 1340, and the light emitting element EL shown in FIG. 10 operate in the reset phase TR, the compensation phase TC, and the data writing phase. The implementation details of the TDA and the light-emitting phase TE can be deduced by analogy with reference to the related descriptions of FIG. 6A and FIG. 6B, and therefore will not be repeated.

FIG. 12 is a flowchart of a driving method of the pixel circuit 100 according to the embodiment of FIG. 1 of the present invention. 1 and 12 at the same time, in step S1210, the pixel circuit 100 may provide a driving transistor having a driving end, a first end, and a second end. In step S1220, the pixel circuit 100 may provide an initialization circuit to adjust the voltage levels of the input terminal and the driving terminal according to the previous gate drive signal. In step S1230, the pixel circuit 100 may provide a data writing circuit to provide a data voltage to the input terminal according to the gate driving signal. In step S1240, the pixel circuit 100 may provide a voltage compensation circuit to adjust the voltage level of the driving terminal according to the compensation control signal. In step S1250, the pixel circuit 100 may provide a light-emitting element having a cathode terminal and an anode terminal. In step S1260, the pixel circuit 100 may provide a first light emitting control circuit to control the light emitting state of the light emitting element according to the light emitting control signal, wherein the enable time of the compensation control signal is between the falling edge of the previous gate drive signal and the gate Between the rising edges of the pole drive signal.

FIG. 13 is a flowchart of a driving method of the pixel circuit 900 according to the embodiment of FIG. 5 of the present invention. Referring to FIG. 5 and FIG. 13 at the same time, in step S1310, the pixel circuit 900 may provide a driving transistor having a driving end, a first end, and a second end. In step S1320, the pixel circuit 900 may provide an initialization circuit to adjust the voltage levels of the input terminal and the driving terminal based on the reference voltage and the gate drive signal and the previous gate drive signal. In step S1330, the pixel circuit 900 may provide a data writing circuit to provide a data voltage to the input terminal according to the gate drive signal. In step S1340, the pixel circuit 900 may provide a voltage compensation circuit to adjust the voltage level of the driving terminal according to the gate driving signal and the previous gate driving signal during the compensation phase. In step S1350, the pixel circuit 900 may provide a light-emitting element having a cathode terminal and an anode terminal. In step S1360, the pixel circuit 900 may provide a light emitting control circuit to control the light emitting state of the light emitting element according to the control signal, wherein the compensation phase is between the falling edge of the previous gate drive signal and the rising edge of the gate drive signal .

The implementation details of the steps in FIG. 12 and FIG. 13 are described in detail in the foregoing embodiments and implementations, and will not be repeated here.

In summary, the pixel circuits of the embodiments of the present invention can set the enable time of the compensation control signal to be between the falling edge of the previous gate drive signal and the rising edge of the gate drive signal. As a compensation time for compensating the critical voltage of the driving transistor. In this way, compared to the conventional pixel circuit which can only compensate for the threshold voltage of the driving transistor during the limited enable period of the gate drive signal, the pixel circuit of the present invention can compensate by lengthening The enabling time of the control signal is used to increase the compensation time for the threshold voltage of the driving transistor, thereby effectively improving the quality of the display image.

100～1300: pixel circuit 110～1310: Initialization circuit 120～1320: Voltage compensation circuit 130～1330: Data writing circuit 140～1340: Light-emitting control circuit 450～850: Leakage current compensation circuit 460～860: Light-emitting control circuit C1: Capacitor CS: Control signal EM: Luminous control signal EL: Light-emitting element ID: On-current PIN: input PD: drive end RN: Compensation control signal SN: Gate drive signal SN-m: Front gate drive signal SN+i: Rear gate drive signal S1210～S1260, S1310～S1360: steps T1～T8: Transistor TD: drive transistor TDA: data writing stage TE: light-emitting stage TR: reset phase TC: compensation stage VGH: Very high gate voltage VDATA: data voltage VREF: Reference voltage VDD, VSS: system voltage VREF: Reference voltage

FIG. 1 is a schematic diagram of a pixel circuit according to an embodiment of the invention. 2A to 2G are circuit diagrams showing pixel circuits of different embodiments of the present invention according to the pixel circuit of the embodiment of FIG. 1. 3 is a schematic diagram of waveforms of an embodiment of the pixel circuit of FIGS. 2A to 2G according to the present invention. 4 is a schematic diagram of waveforms of another embodiment of the pixel circuit of FIGS. 2A to 2G according to the present invention. FIG. 5 is a schematic diagram of a pixel circuit according to another embodiment of the invention. 6A to 6B are circuit diagrams showing pixel circuits of different embodiments of the present invention according to the pixel circuit of the embodiment of FIG. 5. FIG. 7 is a schematic diagram of waveforms of the pixel circuits of FIGS. 6A to 6B according to the present invention. FIG. 8 is a circuit diagram of a pixel circuit of a different embodiment of the present invention according to the pixel circuit of the embodiment of FIG. 5. FIG. 9 is a schematic diagram of waveforms of the pixel circuit of FIG. 8 according to the present invention. FIG. 10 is a circuit diagram of a pixel circuit of a different embodiment of the present invention according to the pixel circuit of the embodiment of FIG. 5. FIG. 11 is a schematic diagram of waveforms of the pixel circuit of FIG. 10 according to the present invention. FIG. 12 is a flowchart of the driving method of the pixel circuit according to the embodiment of FIG. 1 of the present invention. FIG. 13 is a flowchart of the driving method of the pixel circuit according to the embodiment of FIG. 5 of the present invention.

100: pixel circuit

110: Initialization circuit

120: Voltage compensation circuit

130: Data writing circuit

140: Light-emitting control circuit

EM: Luminous control signal

EL: Light-emitting element

ID: On-current

VDD, VSS: system voltage

PIN: input

PD: drive end

RN: Compensation control signal

SN: Gate drive signal

SN-m: Front-stage gate drive signal

TD: drive transistor

VDATA: data voltage

VREF: Reference voltage

Claims (29)

A pixel circuit includes: a drive transistor having a drive end and a first end coupled to a first system voltage; an initialization circuit, coupled to an input end and the drive end, according to a front-stage gate A drive signal is used to adjust the voltage levels of the input terminal and the drive terminal; a data writing circuit, coupled to the input terminal, provides a data voltage to the input terminal according to a gate drive signal; a voltage compensation circuit, Is coupled to the input terminal and the drive terminal, and adjusts the voltage level of the drive terminal according to a compensation control signal; a light emitting element having a cathode terminal and an anode terminal coupled to a second system voltage; and a first The light-emitting control circuit is coupled to the cathode terminal of the light-emitting element, the voltage compensation circuit, and the second terminal of the driving transistor, and controls the light-emitting state of the light-emitting element according to a light-emitting control signal, wherein the compensation control signal causes The energy time is between the falling edge of the previous gate drive signal and the rising edge of the gate drive signal. In a reset phase, the initialization circuit pulls the previous gate drive signal high. Increase the voltage level of the input terminal and the drive terminal. The pixel circuit according to claim 1, wherein in a compensation stage, the voltage compensation circuit makes the voltage of the driving terminal accurate according to the compensation control signal that is pulled up. The bit is the sum of the voltage value of the first system voltage and the voltage value of the threshold voltage of the driving transistor. The pixel circuit according to claim 1, wherein in a data writing phase and a light emitting phase, the voltage compensation circuit makes the voltage level of the driving terminal the voltage value of the data voltage according to the compensation control signal that is pulled down , The difference between the voltage value of the threshold voltage of the driving transistor and the voltage value of the first system voltage and the voltage value of a reference voltage. The pixel circuit according to claim 1, wherein in a data writing phase and a light emitting phase, the voltage compensation circuit makes the voltage level of the driving terminal the voltage value of the data voltage according to the compensation control signal that is pulled down And the sum of the voltage values of the threshold voltage of the driving transistor. The pixel circuit according to claim 1, wherein the pixel circuit further comprises: a second light-emitting control circuit coupled to the first terminal of the driving transistor and the first system voltage, wherein in a light-emitting phase, The first light-emitting control circuit and the second light-emitting circuit are turned on according to the light-emitting control signal that is pulled high, and the light-emitting element is turned on. The pixel circuit according to claim 5, wherein the pixel circuit further comprises: a leakage current compensation circuit, which is coupled in parallel to the second light-emitting control circuit, and is based on the compensation control signal that is pulled up during a compensation stage And provide a leakage current catharsis path. The pixel circuit according to claim 6, wherein the second light-emitting control circuit includes: a first transistor, the first terminal of which is coupled to the first system voltage, and the second terminal of which is coupled to the driving transistor The control terminal receives the light emission control signal, wherein the leakage current compensation circuit includes: a second transistor, the first terminal of which is coupled to the first terminal of the first transistor, and the second terminal of which is coupled to Connected to the second end of the first transistor, the control end of which receives the compensation control signal, wherein the aspect ratio of the second transistor is smaller than the aspect ratio of the first transistor. The pixel circuit according to claim 5, wherein the pixel circuit further comprises: a leakage current compensation circuit coupled to a reference voltage and the input terminal, wherein the leakage current compensation circuit and the voltage compensation circuit are in a compensation The stage provides a leakage current catharsis path according to the compensation control signal that is pulled up. The pixel circuit according to claim 8, wherein the second light-emitting control circuit includes: a first transistor, the first terminal of which is coupled to the first system voltage, and the second terminal of which is coupled to the driving transistor The control terminal receives the light emission control signal, wherein the leakage current compensation circuit includes: a second transistor, the first terminal of which is coupled to the input terminal, and the second terminal of which is coupled to the reference voltage, The control terminal receives the compensation control signal, wherein the aspect ratio of the second transistor is smaller than the aspect ratio of the first transistor. A driving method of a pixel circuit includes: providing a driving transistor having a driving end, a first end, and a second end; providing an initialization circuit to adjust an input end and the Provide a data write circuit to provide a data voltage to the input terminal based on a gate drive signal; provide a voltage compensation circuit to adjust the voltage level of the drive terminal based on a compensation control signal; provide A light emitting element having a cathode end and an anode end; and a first light emitting control circuit is provided to control the light emitting state of the light emitting element according to a light emitting control signal, wherein the activation time of the compensation control signal is between the front gate Between the falling edge of the gate drive signal and the rising edge of the gate drive signal, and during a reset phase, the initialization circuit pulls up the input terminal and the drive signal according to the previous gate drive signal that is pulled up. The voltage level of the terminal. The driving method according to claim 10, further comprising: in a compensation stage, the voltage compensation circuit makes the voltage level of the driving terminal be the voltage value of the first system voltage and the The sum of the voltage values of the critical voltage for driving the transistor. The driving method according to claim 10, further comprising: in a data writing phase and a light emitting phase, the voltage compensation circuit makes the voltage level of the driving terminal be lower than the data voltage according to the compensation control signal that is pulled down The difference between the voltage value, the voltage value of the threshold voltage of the driving transistor, and the voltage value of the first system voltage and the voltage value of a reference voltage. The driving method according to claim 10, further comprising: in a data writing phase and a light emitting phase, the voltage compensation circuit makes the voltage level of the driving terminal be lower than the data voltage according to the compensation control signal that is pulled down The sum of the voltage value and the voltage value of the threshold voltage of the drive transistor. The driving method according to claim 10, further comprising: providing the first light-emitting control circuit and a second light-emitting control circuit in a light-emitting stage to be turned on according to the light-emitting control signal that is pulled high, and the light-emitting element is Light up. The driving method according to claim 14, further comprising: providing a leakage current compensation circuit in a compensation stage to provide a leakage current venting path according to the compensation control signal that is pulled up. The driving method according to claim 14, further comprising: providing the voltage compensation circuit and a leakage current compensation circuit in a compensation stage to provide a leakage current leakage path according to the compensation control signal that is pulled up. A pixel circuit includes: a driving transistor, having a driving end and a first end coupled to a first system voltage; an initialization circuit, coupled to an input end and the driving end, for being based on a reference Voltage, and adjust the voltage levels of the input terminal and the drive terminal according to a gate drive signal and a previous-stage gate drive signal; A data writing circuit is coupled to the input terminal and provides a data voltage to the input terminal according to the gate drive signal; a voltage compensation circuit is coupled to the initialization circuit, and the voltage compensation circuit is used for a compensation The stage adjusts the voltage level of the drive terminal according to the gate drive signal and the previous stage gate drive signal; a light-emitting element having a cathode terminal and an anode terminal coupled to a second system voltage; and a light-emitting control circuit , Coupled to the cathode end of the light-emitting element, the voltage compensation circuit, and the second end of the driving transistor, and control the light-emitting state of the light-emitting element according to a control signal, wherein the compensation stage is between the previous gate Between the falling edge of the drive signal and the rising edge of the gate drive signal. The pixel circuit according to claim 17, wherein the control signal is the gate drive signal, a light emission control signal, or a subsequent gate drive signal. The pixel circuit according to claim 17, wherein the reference voltage is the second system voltage. The pixel circuit according to claim 17, wherein in a reset phase, the initialization circuit raises the voltage levels of the input terminal and the driving terminal according to the previous-stage gate driving signal that is pulled high. The pixel circuit according to claim 17, wherein in the compensation stage, the voltage compensation circuit is pulled down according to the gate drive signal and the front-stage gate The polar driving signal makes the voltage level of the driving terminal the sum of the voltage value of the first system voltage and the voltage value of the threshold voltage of the driving transistor. The pixel circuit according to claim 17, wherein in a light-emitting phase, the data writing circuit is turned on according to the gate drive signal that is pulled high to provide the data voltage to the input terminal, and the initialization circuit And the voltage compensation circuit is turned off according to the previous gate drive signal that is pulled down, so that the voltage level of the drive terminal is the voltage value of the data voltage, the voltage value of the threshold voltage of the drive transistor, and the first The difference between the sum of the voltage values of the system voltage and the voltage value of the second system voltage or the reference voltage. The pixel circuit according to claim 17, wherein the initialization circuit includes: a first transistor whose second terminal and the control terminal jointly receive the previous-stage gate drive signal; and a second transistor whose first terminal Is coupled to the first terminal of the first transistor, the second terminal of which receives the previous gate drive signal, and the control terminal of which receives the gate drive signal; a third transistor, the first terminal of which is coupled to the Input terminal, the second terminal of which is coupled to the reference voltage, the control terminal of which is coupled to the first terminal of the second transistor; a fourth transistor, the first terminal and the control terminal of which jointly receive the front-stage gate The second end of a driving signal is coupled to the driving end; and a capacitor, the first end of which is coupled to the input end, and the second end of which is coupled to the driving end. A driving method of a pixel circuit includes: Provide a drive transistor with a drive end, a first end and a second end; provide an initialization circuit based on a reference voltage and adjust an input end according to a gate drive signal and a previous-stage gate drive signal And the voltage level of the driving terminal; providing a data writing circuit to provide a data voltage to the input terminal according to the gate driving signal; providing a voltage compensation circuit to according to the gate driving signal and the front in a compensation stage A stage gate drive signal is used to adjust the voltage level of the drive terminal; a light-emitting element having a cathode terminal and an anode terminal is provided; and a light-emitting control circuit is provided to control the light-emitting state of the light-emitting element according to a control signal, wherein the compensation The stage is between the falling edge of the previous gate drive signal and the rising edge of the gate drive signal. The driving method according to claim 24, wherein the control signal is the gate driving signal, a light-emitting control signal, or a subsequent gate driving signal. The driving method according to claim 24, wherein the reference voltage is a second system voltage. The driving method according to claim 24, further comprising: in a reset phase, the initialization circuit raises the voltage levels of the input terminal and the driving terminal according to the pulled-up front-stage gate driving signal. The driving method described in claim 24 further includes: In the compensation stage, the voltage compensation circuit makes the voltage level of the driving terminal a voltage value of the first system voltage and the driving transistor according to the gate drive signal that is pulled down and the previous gate drive signal The sum of the voltage values of the critical voltage. The driving method according to claim 24, further comprising: in a light-emitting phase, the data writing circuit is turned on according to the gate driving signal that is pulled high to provide the data voltage to the input terminal, and The initialization circuit and the voltage compensation circuit are disconnected according to the pulled-down previous gate drive signal, so that the voltage level of the drive terminal is the voltage value of the data voltage, the voltage value of the threshold voltage of the drive transistor, and The difference between the sum of the voltage values of a first system voltage and the voltage value of a second system voltage or the reference voltage.

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