Pixel circuit and driving method thereof, and display panel

Abstract

The present invention discloses a pixel circuit and a driving method thereof, and a display panel. The pixel circuit includes: a driving module, which generates a driving current in response to the voltage of its control end; a first light-emitting control module and a second light-emitting control module, wherein the first light-emitting control module is connected between the first end of the driving module and the anode of the light-emitting element, and the second light-emitting control module is connected between the second end of the driving module and the first power supply signal line; a reverse bias module, which is connected between the first end of the driving module and the reverse bias signal line, and adjusts the voltage between the control end and the first end of the driving module according to the reverse bias signal on the reverse bias signal line in the bias stage to reverse bias the driving module, and is used to transmit the reverse bias signal to the driving module in the first initialization stage to initialize the control end, the first end, and the second end of the driving module. Accordingly, the flickering phenomenon during low-frequency display is improved, and the display effect is improved.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a pixel circuit and a driving method thereof, and a display panel. Background Art

[0002] Active Matrix Organic Light Emitting Diode (AMOLED) has broad application prospects in the display field due to its excellent performance such as low power consumption, high color saturation and wide viewing angle.

[0003] As the demand for longer standby time of display products increases, low-frequency display is the general trend. However, the AMOLED display panel of the related art flickers when displaying at a low frequency, resulting in poor display effect. Summary of the invention

[0004] The present invention provides a pixel circuit and a driving method thereof, and a display panel, so as to improve the flickering phenomenon of the display panel during low-frequency display and enhance the display effect.

[0005] According to one aspect of the present invention, there is provided a pixel circuit, comprising:

[0006] A driving module, comprising a control terminal, a first terminal and a second terminal, wherein the driving module is used to generate a driving current in response to a voltage at the control terminal;

[0007] A data writing module, connected between the first end of the driving module and the data line, and used for transmitting the data voltage on the data line to the control end of the driving module during the data writing phase;

[0008] a light emitting element, configured to emit light in response to the driving current;

[0009] A first light-emitting control module and a second light-emitting control module, wherein the first light-emitting control module is connected between the first end of the driving module and the anode of the light-emitting element, and the second light-emitting control module is connected between the second end of the driving module and the first power signal line, and the first light-emitting control module and the second light-emitting control module are used to control the light-emitting element to emit light in the light-emitting stage;

[0010] A reverse bias module is connected between the first end of the driving module and the reverse bias signal line, and is used to adjust the voltage between the control end and the first end of the driving module according to the reverse bias signal on the reverse bias signal line in the bias stage to reverse bias the driving module, and is used to transmit the reverse bias signal to the driving module in the first initialization stage to initialize the control end, the first end and the second end of the driving module.

[0011] Optionally, the reverse bias module includes a first transistor;

[0012] The first end of the first transistor is connected to the first end of the driving module, the second end of the first transistor is connected to the reverse bias signal line, and the control end of the first transistor is connected to the first scanning signal line;

[0013] Preferably, the driving module comprises a driving transistor, the driving transistor is an NMOS transistor, and the control end, the first end and the second end of the driving transistor serve as the control end, the first end and the second end of the driving module respectively;

[0014] Preferably, the first transistor is an NMOS transistor.

[0015] Optionally, the reverse bias module is used to adjust the voltage between the control terminal and the first terminal of the driving module according to the reverse bias signal between the data writing stage and the light emitting stage, so as to reverse bias the driving module;

[0016] And / or, the first light-emitting control module is used to control the light-emitting element to light up at least twice within the light-emitting stage, and the reverse bias module is used to adjust the voltage between the control end and the first end of the driving module according to the reverse bias signal between at least partially adjacent two lightings to reverse bias the driving module.

[0017] Optionally, a threshold compensation module is also included;

[0018] The threshold compensation module is connected between the second end of the driving module and the control end, and is used to compensate the threshold voltage of the driving module during the data writing phase;

[0019] Preferably, the data writing module includes a second transistor, the second transistor is an NMOS transistor, a first end of the second transistor is connected to the first end of the driving module, a second end of the second transistor is connected to the data line, and a control end of the second transistor is connected to the second scanning signal line;

[0020] Preferably, the threshold compensation module includes a third transistor, which is an NMOS transistor, a first end of the third transistor is connected to the second end of the driving module, a second end of the third transistor is connected to the control end of the driving module, and the control end of the third transistor is connected to a third scanning signal line.

[0021] Optionally, it also includes a first initialization module and a storage module;

[0022] The first initialization module is connected between the first end of the storage module and the first initialization signal line, and is used to transmit the first initialization signal on the first initialization signal line to the anode of the light-emitting element in the first initialization stage and / or the bias stage;

[0023] The first end of the storage module is connected to the anode of the light-emitting element, and the second end of the storage module is connected to the control end of the driving module. The storage module is used to store the voltage of the control end of the driving module and to couple the voltage variation of the anode of the light-emitting element to the control end of the driving module.

[0024] Preferably, the first initialization module includes a fourth transistor, which is an NMOS transistor, the first end of the fourth transistor is connected to the first end of the storage module, the second end of the fourth transistor is connected to the first initialization signal line, and the control end of the fourth transistor is connected to the first scanning signal line or the fourth scanning signal line.

[0025] Optionally, it also includes a second initialization module;

[0026] The second initialization module is connected between the control end of the driving module and the second initialization signal line, and is used to transmit the second initialization signal on the second initialization signal line to the driving module in a second initialization phase performed after the first initialization phase, so as to initialize the control end of the driving module;

[0027] Preferably, the second initialization module comprises a seventh transistor, the seventh transistor is an NMOS transistor, a first end of the seventh transistor is connected to the control end of the driving module, a second end of the seventh transistor is connected to the second initialization signal line, and a control end of the seventh transistor is connected to the fifth scanning signal line;

[0028] Preferably, the second light emitting control module comprises a fifth transistor, the fifth transistor is an NMOS transistor, a first end of the fifth transistor is connected to the second end of the driving module, a second end of the fifth transistor is connected to the first power signal line, and a control end of the fifth transistor is connected to the light emitting control signal line;

[0029] Preferably, the first light-emitting control module includes a sixth transistor, which is an NMOS transistor, a first end of the sixth transistor is connected to the first end of the driving module, a second end of the sixth transistor is connected to the anode of the light-emitting element, and a control end of the sixth transistor is connected to the light-emitting control signal line.

[0030] According to another aspect of the present invention, a display panel is provided, comprising the pixel circuit as described in the above aspect.

[0031] According to another aspect of the present invention, a driving method for a pixel circuit is provided, comprising: in a first initialization stage, controlling the reverse bias module to be turned on, the reverse bias module transmitting the reverse bias signal to the driving module to initialize the control terminal, the first terminal and the second terminal of the driving module;

[0032] In the data writing stage, the data writing module is controlled to be turned on, and the data writing module transmits the data voltage to the driving module;

[0033] In the biasing stage, the reverse biasing module is controlled to be turned on, and the reverse biasing module adjusts the voltage between the control terminal and the first terminal of the driving module according to the reverse biasing signal, so as to reverse bias the driving module;

[0034] In the light-emitting stage, the first light-emitting control module is controlled to be turned on, the driving module generates the driving current in response to the voltage at its control end, and the light-emitting element emits light in response to the driving current.

[0035] Optionally, the light emitting stage includes:

[0036] The first light-emitting control module is controlled to be turned on at least twice so that the light-emitting element is lit at least twice; meanwhile, the reverse bias module is controlled to be turned on between at least partially adjacent two lightings, and the reverse bias module adjusts the voltage between the control end and the first end of the driving module according to the reverse bias signal so that the driving module is reverse biased.

[0037] Optionally, the pixel circuit further includes a second initialization module, wherein the second initialization module is connected between the control terminal of the driving module and the second initialization signal line;

[0038] The first initialization phase and the data writing phase also include:

[0039] In the second initialization stage, the second initialization module is controlled to be turned on, and the second initialization module transmits the second initialization signal to the driving module to initialize the control end of the driving module.

[0040] The technical solution of the embodiment of the present invention, the pixel circuit includes a driving module, a data writing module, a light-emitting element and a first light-emitting control module; wherein the driving module includes a control terminal, a first terminal and a second terminal, the driving module is used to generate a driving current in response to the voltage of its control terminal, the data writing module is connected between the driving module and the data line, the data writing module is used to transmit the data voltage on the data line to the driving module in the data writing stage, the light-emitting element is used to emit light in response to the driving current, the first light-emitting control module is connected between the first terminal of the driving module and the anode of the light-emitting element, and the first light-emitting control module is used to control the light-emitting element in the light-emitting stage. On this basis, by setting the pixel circuit to also include a reverse bias module, the reverse bias module is connected between the first terminal of the driving module and the reverse bias signal line, the reverse bias module is used to adjust the voltage between the control terminal and the first terminal of the driving module according to the reverse bias signal on the reverse bias signal line in the bias stage, so that the driving module is reverse biased, thereby improving the characteristic drift phenomenon of the driving module during low-frequency display, optimizing the device stability and reliability of the driving module, thereby improving the flicker phenomenon caused by the characteristic drift phenomenon of the driving module during low-frequency display, and improving the display effect of the display panel.

[0041] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 is a schematic diagram of the structure of a pixel circuit in an AMOLED display panel of the related art;

[0044] Figure 2 is a structural schematic diagram of a pixel circuit provided by an embodiment of the present invention;

[0045] Figure 3 is a structural schematic diagram of another pixel circuit provided by an embodiment of the present invention;

[0046] Figure 4 is a structural schematic diagram of another pixel circuit provided by an embodiment of the present invention;

[0047] Figure 5 is a driving timing diagram of a pixel circuit provided by an embodiment of the present invention;

[0048] Figure 6 It is a schematic diagram of the structure of a display panel provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0051] As mentioned in the background technology, the AMOLED display panel of the related art flickers when displaying at a low frequency. The inventors have found that the reason is:

[0052] refer to Figure 1 , Figure 1It is a structural schematic diagram of a pixel circuit in an AMOLED display panel of the related technology. The pixel circuit is a PMOS 7T1C pixel circuit, which includes: an OLED element, a driving transistor M0, a data writing transistor M1, a storage capacitor Cst, a threshold compensation transistor M2, a first initialization transistor M3, a second initialization transistor M4, a first light-emitting control transistor M5 and a second light-emitting control transistor M6. In the initialization stage, the first initialization transistor M3 and the second initialization transistor M4 transmit the initialization voltage Vref to the control end of the driving transistor M0 and the anode of the OLED element respectively to initialize the control end of the driving transistor M0 and the anode of the OLED element; in the data writing stage, the data writing transistor M1 transmits the data voltage Vdata to the control end of the driving transistor M0, and at the same time the threshold compensation transistor M2 compensates the threshold voltage VthVth of the driving transistor M0, and finally the voltage of the control end of the driving transistor M0 is Vdata+Vth, and the storage capacitor Cst stores the voltage of the control end of the driving transistor M0; in the light emitting stage, the first light emitting control transistor M5 and the second light emitting control transistor M6 are turned on, the driving transistor M0 generates a driving current in response to the voltage of its own control end, and the OLED element emits light in response to the driving current.

[0053] In the above pixel circuit, the driving transistor M0 works in a positive bias state to provide a driving current to the OLED element. When the driving transistor M0 works in a bias state for a long time, the threshold voltage VthVth will drift. When the display panel displays a static image, for two adjacent display frames, the brightness at the start of the display of the latter display frame is substantially the same as the brightness at the start of the display of the former display frame. At this time, if the display panel is a low-frequency display, the brightness of the former display frame will drop rapidly within one frame time due to the drift of the threshold voltage Vth of the driving transistor M0. Finally, there will be a large difference between the brightness at the end of the display of the former display frame and the brightness at the start of the display. In this way, from the end of the display of the former display frame to the start of the display of the latter display frame, there will be a large difference in brightness jump, showing a flickering phenomenon.

[0054] In view of this, an embodiment of the present invention provides a pixel circuit and a driving method thereof, and a display panel to improve the flickering phenomenon of the display panel during low-frequency display and enhance the display effect.

[0055] Figure 2 is a schematic diagram of a pixel circuit provided by an embodiment of the present invention, with reference to Figure 2The pixel circuit includes: a driving module 10, a data writing module 20, a storage module 90, a light emitting element D, a first light emitting control module 30, a second light emitting control module 80 and a reverse bias module 40; the driving module 10 includes a control terminal e, a first terminal f and a second terminal m, and the driving module 10 is used to generate a driving current in response to the voltage of its control terminal; the data writing module 20 is connected between the first terminal of the driving module 10 and the data line DATA, and is used to transmit the data voltage Vdata on the data line DATA to the control terminal of the driving module 10 during the data writing stage; the light emitting element D is used to emit light in response to the driving current; the first light emitting control module 30 is connected between the first terminal of the driving module 10 and the anode of the light emitting element D The second light-emitting control module 80 is connected between the second end of the driving module 10 and the first power signal line (VDD), and the first light-emitting control module 30 and the second light-emitting control module 80 are used to control the light-emitting element D in the light-emitting stage; the reverse bias module 40 is connected between the first end of the driving module 10 and the reverse bias signal line VREF3, and is used to adjust the voltage between the control end and the first end of the driving module 10 according to the reverse bias signal Vref3 on the reverse bias signal line VREF3 in the bias stage to reverse bias the driving module 10, and is used to transmit the reverse bias signal Vref3 to the driving module 10 in the first initialization stage to initialize the control end, the first end and the second end of the driving module 10.

[0056] Specifically, the display panel may be an OLED display panel, wherein the light emitting element D is an OLED element. The display panel may include a plurality of data lines DATA extending in the column direction and a plurality of scanning signal lines SCAN extending in the row direction. The data line DATA is used to provide the data voltage Vdata required for the picture display, and different data voltages Vdata correspond to different display grayscales; the scanning signal on the scanning signal line SCAN is used to control the conduction or shutdown of the corresponding module in the pixel circuit, wherein the pixel circuit is located in the intersection area of ​​the data line DATA and the scanning signal line. The display panel may also include a light emitting control signal line EM and a reverse bias signal line VREF3. The light emitting control signal on the light emitting control signal line EM can control the conduction or shutdown of the first light emitting control module 30 in the pixel circuit, and control the conduction or shutdown of the second light emitting control module 80, and the second light emitting control module 80 and the first light emitting control module 30 can jointly control the light emitting of the light emitting element D in the light emitting stage; the reverse bias signal line VREF3 can provide a reverse bias signal Vref3 to the pixel circuit, and the reverse bias signal Vref3 is a voltage signal with adjustable size.

[0057] The driving module 10 may include a driving transistor T0, which is, for example, an NMOS transistor. The control terminal, the first terminal, and the second terminal of the driving transistor T0 may be used as the control terminal, the first terminal, and the second terminal of the driving module 10, respectively. The data writing module 20 may be connected between the control terminal of the driving module 10 and the data line DATA, or between the first terminal of the driving module 10 and the data line DATA, so as to transmit the data voltage Vdata to the control terminal of the driving module 10, and the storage module 90 stores the voltage of the control terminal of the driving module 10. The second terminal of the driving module 10 may be connected to the first power signal VDD, and the cathode of the light-emitting element D may be connected to the second power signal VSS; the driving module 10 may generate a driving current according to the voltage between its control terminal and the first terminal, and the light-emitting element D emits light in response to the driving current. The first light-emitting control module 30 is connected between the first terminal of the driving module 10 and the anode of the light-emitting element D, so as to control the lighting or extinguishing of the light-emitting element D. The reverse bias module 40 is connected between the first end of the driving module 10 and the reverse bias signal line VREF3, so that the voltage between the control end and the first end of the driving module 10 can be adjusted according to the reverse bias signal Vref3 on the reverse bias signal line VREF3. For example, by adjusting the voltage of the first end of the driving module 10 according to the reverse bias signal Vref3, the voltage between the control end and the first end of the driving module 10 is adjusted.

[0058] Based on the above, in this embodiment, the pixel circuit may include at least a first initialization stage, a second initialization stage, a data writing stage, a bias stage and a light emitting stage within one frame time. In the second initialization stage, the control end of the driving module 10 may be initialized using the initialization voltage Vref. In the data writing stage, the data writing module 20 transmits the data voltage Vdata to the control end of the driving module 10, the storage module 90 stores the voltage of the control end of the driving module 10, and the driving module 10 enters a positive bias state. When the driving module 10 works in a bias state for a long time, the threshold voltage Vth may drift.

[0059] In this regard, a bias stage is set in the present embodiment. In the bias stage, the reverse bias module 40 is set to adjust the voltage of the first end of the driving module 10 according to the reverse bias signal Vref3. For example, the reverse bias module 40 transmits the reverse bias signal Vref3 to the first end of the driving module 10, thereby adjusting the voltage between the control end and the first end of the driving module 10, so that the driving module 10 is reversely biased, thereby pulling back the drift of the threshold voltage Vth of the driving module 10, reducing the drift amount of the threshold voltage Vth of the driving module 10. The embodiment of the present invention thereby improves the characteristic drift phenomenon of the driving module 10 during low-frequency display, optimizes the device stability and reliability of the driving module 10, thereby improving the flicker phenomenon caused by the characteristic drift phenomenon of the driving module 10 during low-frequency display, and improves the display effect of the display panel. For example, when the display panel is refreshed at a low frequency and displays a still image, for two adjacent display frames, since the drift of the threshold voltage Vth of the driving module 10 in the previous display frame is pulled back by the reverse bias module 40 according to the reverse bias signal Vref3, the drift amount is reduced, so that the difference between the brightness at the end of the previous display frame and the brightness at the start of the display is small. In this way, the brightness jump from the end of the previous display frame to the start of the next display frame is very small, and the human eye can hardly perceive the flicker phenomenon.

[0060] In addition, in the present embodiment, a first initialization stage is set. In the first initialization stage, the reverse bias module 40 can write the reverse bias signal Vref3 into the control end, the first end and the second end of the driving module 10 in sequence, so that the reverse bias signal Vref3 can be used to eliminate the influence of the drift of the threshold voltage Vth of the driving module 10 of the previous display frame on the second initialization stage and the data writing stage of the next display frame, thereby improving the ghosting and further enhancing the display effect.

[0061] Figure 3 is a schematic diagram of another pixel circuit provided by an embodiment of the present invention, referring to Figure 3 On the basis of the above embodiment, optionally, the reverse bias module 40 includes a first transistor T1; the first end of the first transistor T1 is connected to the first end of the driving module 10, the second end of the first transistor T1 is connected to the reverse bias signal line VREF3, and the control end of the first transistor T1 is connected to the first scan signal line SCAN1.

[0062] Specifically, in the bias stage, the first transistor T1 transmits the reverse bias signal Vref3 to the first end of the driving transistor T0 to adjust the voltage of the first end of the driving transistor T0, thereby realizing the adjustment of the voltage between the control end and the first end of the driving transistor T0, so that the driving transistor T0 is reverse biased, and the drift of the threshold voltage Vth of the driving transistor T0 is pulled back in the reverse direction, thereby reducing the drift amount of the threshold voltage Vth of the driving transistor T0.

[0063] Exemplarily, when the voltage Vg of the control terminal of the driving transistor T0 is 5 volts and the voltage Vs of the first terminal of the driving transistor T0 is 0 volts, that is, the voltage Vgs between the control terminal and the first terminal of the driving transistor T0 is 5 volts, if the driving transistor T0 enters a forward biased state at this time, and in order to reverse bias the driving transistor T0, the reverse bias signal Vref3 can be set to 10 volts according to actual needs, thereby adjusting the voltage of the first terminal of the driving transistor T0 to 10 volts. In this way, the voltage Vgs between the control terminal and the first terminal of the driving transistor T0 is adjusted to negative 5 volts, that is, less than the original 5 volts, thereby pulling back the drift of the threshold voltage Vth of the driving transistor T0, thereby reducing the drift amount of the threshold voltage Vth of the driving transistor T0.

[0064] The pixel circuit of this embodiment, on the basis of adding an independent reverse bias module 40, is provided with the reverse bias module 40 including a first transistor T1, so that the structure of the reverse bias module 40 is simple, and the first transistor T1 can be manufactured in the same process as other transistors in the pixel circuit, and the manufacturing cost of the pixel circuit is relatively low.

[0065] Continue to refer Figure 3 , this embodiment exemplarily illustrates that the driving transistor T0 and the first transistor T1 are both NMOS transistors. Among them, the driving transistor T0 and the first transistor T1 can both use oxide semiconductor transistors, such as indium gallium zinc oxide semiconductor transistors (IGZO). Oxide semiconductor transistors have the advantages of high mobility, good uniformity, transparency, simple manufacturing process, etc., and have good threshold voltage Vth uniformity, smaller leakage current, and lower hysteresis effect, which helps to stabilize the voltage of the control terminal of the driving transistor T0.

[0066] Figure 4 is a schematic diagram of another pixel circuit provided by an embodiment of the present invention, referring to Figure 4On the basis of the above embodiment, optionally, the data writing module 20 includes a second transistor T2, the second transistor T2 is an NMOS transistor, the first end of the second transistor T2 is connected to the first end of the driving module 10, the second end of the second transistor T2 is connected to the data line DATA, and the control end of the second transistor T2 is connected to the second scanning signal line SCAN2. The second transistor T2 can be an oxide semiconductor transistor, such as an indium gallium zinc oxide semiconductor transistor (IGZO).

[0067] Optionally, the pixel circuit further includes a threshold compensation module 50; the threshold compensation module 50 is connected between the second end and the control end of the driving module 10, and is used to compensate the threshold voltage Vth of the driving module 10 during the data writing stage, and finally the voltage of the control end of the driving module 10 is Vdata+Vth. Optionally, the threshold compensation module 50 includes a third transistor T3, the third transistor T3 is an NMOS transistor, the first end of the third transistor T3 is connected to the second end of the driving module 10, the second end of the third transistor T3 is connected to the control end of the driving module 10, and the control end of the third transistor T3 is connected to the third scanning signal line SCAN3. Among them, the third transistor T3 can be an oxide semiconductor transistor, such as an indium gallium zinc oxide semiconductor transistor (IGZO), so as to stabilize the voltage of the control end of the driving transistor T0.

[0068] Continue to refer Figure 4 Optionally, a first end of the storage module 90 is connected to the anode of the light emitting element D, and a second end of the storage module 90 is connected to the control end of the driving module 10. The storage module 90 is used to store the voltage of the control end of the driving module 10 and to couple the voltage variation of the anode of the light emitting element D to the control end of the driving module 10. Optionally, the storage module 90 includes a storage capacitor Cst.

[0069] Continue to refer Figure 4 Optionally, the pixel circuit further includes a first initialization module 60 and a second initialization module 70; the first initialization module 60 is connected between the first end of the storage module 90 and the first initialization signal line VREF1, and is used to transmit the first initialization signal Vref1 on the first initialization signal line VREF1 to the anode of the light-emitting element D in the first initialization stage and / or the bias stage to initialize the anode of the light-emitting element D; the second initialization module 70 is connected between the control end of the driving module 10 and the second initialization signal line VREF2, and is used to transmit the second initialization signal Vref2 on the second initialization signal line VREF2 to the driving module 10 in the second initialization stage performed after the first initialization stage to initialize the control end of the driving module 10.

[0070] Optionally, the first initialization module 60 includes a fourth transistor T4, which is an NMOS transistor, a first end of the fourth transistor T4 is connected to the first end of the storage module 90, a second end of the fourth transistor T4 is connected to the first initialization signal line VREF1, and a control end of the fourth transistor T4 is connected to the first scan signal line SCAN1 or the fourth scan signal line SCAN4. Optionally, the second initialization module 70 includes a seventh transistor T7, which is an NMOS transistor, a first end of the seventh transistor T7 is connected to the control end of the driving module 10, a second end of the seventh transistor T7 is connected to the second initialization signal line VREF2, and a control end of the seventh transistor T7 is connected to the fifth scan signal line SCAN5.

[0071] Continue to refer Figure 4 Optionally, the second light-emitting control module 80 includes a fifth transistor T5, which is an NMOS transistor, a first end of which is connected to the second end of the driving module 10, a second end of which is connected to the first power signal line, and a control end of which is connected to the light-emitting control signal line EM. Optionally, the first light-emitting control module 30 includes a sixth transistor T6, which is an NMOS transistor, a first end of which is connected to the first end of the driving module 10, a second end of which is connected to the anode of the light-emitting element D, and a control end of which is connected to the light-emitting control signal line EM.

[0072] In summary, the pixel circuit provided by the embodiment of the present invention is additionally provided with an independent reverse bias module 40, and the voltage between the control terminal and the first terminal of the driving module 10 is adjusted to reverse bias the driving module 10, thereby pulling back the drift of the threshold voltage Vth of the driving module 10, and reducing the drift of the threshold voltage Vth of the driving module 10. The reverse bias module 40 includes an NMOS first transistor T1, thereby forming an NMOS 8T1C circuit, which can not only realize the reverse bias of the driving module 10 and improve the flicker problem of low-frequency display, but also has a smaller leakage current of the entire circuit, and the potential of the control terminal of the driving module 10 is stable, so that the low-frequency display effect is better.

[0073] Based on the above embodiments, an embodiment of the present invention further provides a method for driving a pixel circuit, which is used to drive the pixel circuit provided by any of the above embodiments. Figure 5 is a driving timing diagram of a pixel circuit provided by an embodiment of the present invention, combined with Figure 5 and Figure 4 , the driving method of the pixel circuit includes:

[0074] First initialization stage P1: control the reverse bias module 40, the threshold compensation module 50 and the first initialization module 60 to be turned on, and control the data writing module 20, the second initialization module 70, the first light control module 30 and the second light control module 80 to be turned off. In this way, the reverse bias module 40 transmits the reverse bias signal Vref3 to the driving module 10 to initialize the control end, the first end and the second end of the driving module 10, the voltage of the second node N2 is Vref3, the voltage of the first node N1 and the third node N3 are both Vref3+Vth, and the drift of the threshold voltage Vth of the driving module 10 of the previous display frame on the second initialization stage and the data writing stage of the next display frame is eliminated, that is, the influence of the bias of the driving module 10 of the previous frame on the initialization and data writing process of the current frame is eliminated, and the smear is improved; the first initialization module 60 uses the first initialization signal Vref1 to initialize the anode of the light-emitting element D, and the voltage of the fourth node N4 is Vref1.

[0075] Second initialization stage P2: control the reverse bias module 40, the data writing module 20, the threshold compensation module 50, the first initialization module 60, the first light-emitting control module 30 and the second light-emitting control module 80 to be turned off, and control the second initialization module 70 to be turned on. In this way, the second initialization module 70 uses the second initialization signal Vref2 to initialize the control end of the driving module 10, and the voltage of the first node N1 is Vref2; at the end of this stage, the second initialization module 70 and the threshold compensation module 50 are turned on at the same time, the voltages of the first node N1 and the second node N3 are both Vref2, and the voltage of the second node N2 is Vref2-Vth. Due to the storage capacitor Cst and the capacitance of the light-emitting element D itself, the voltage of the fourth node N4 remains Vref1.

[0076] Data writing stage P3: the reverse bias module 40, the first initialization module 60, the second initialization module 70, the first light-emitting control module 30 and the second light-emitting control module 80 are all turned off, and the data writing module 20 and the threshold compensation module 50 are all turned on. In this way, the data voltage Vdata is written into the control end of the driving module 10, the voltage of the second node N2 is Vdata, the voltages of the first node N1 and the third node N3 are both Vdata+Vth, and the voltage of the fourth node N4 remains Vref1.

[0077] Bias stage P4: the reverse bias module 40 and the first initialization module 60 are both turned on, and the data writing module 20, the threshold compensation module 50, the second initialization module 70, the first light-emitting control module 30 and the second light-emitting control module 80 are all turned off. In this way, the reverse bias module 40 uses the reverse bias signal Vref3 to reset the voltage of the second node N2, and the voltages of the second node N2 and the third node N3 are both Vref3, so that the driving module 10 is reverse biased, and the voltage of the first node N1 remains Vdata+Vth; the first initialization module 60 uses the first initialization signal Vref1 to initialize the anode of the light-emitting element D, and the voltage of the fourth node N4 is Vref1.

[0078] Light-emitting stage P5: Control the reverse bias module 40, the first initialization module 60, the second initialization module 70, the data writing module 20 and the threshold compensation module 50 to be turned off, and control the first light-emitting control module 30 and the second light-emitting control module 80 to be turned on. In this way, the driving module 10 generates a driving current according to the voltage of its own control terminal, and the light-emitting element D emits light in response to the driving current; wherein, at the start time, the voltage of the first node N1 is Vdata+Vth, the voltage of the fourth node N4 is Vref1, and when the first light-emitting control module 30 and the second light-emitting control module 80 are turned on, the voltage of the fourth node N4 and the voltage of the second node N2 are VSS+V OLED , V OLED is the voltage of the light emitting element D. Due to the coupling effect of the storage capacitor Cst, the voltage variation of the anode of the light emitting element D is coupled to the control terminal of the driving module 10, so that the voltage of the first node N1 is: Wherein, Cst can represent the capacitance of the storage capacitor. is the parasitic capacitance of the N1 node; the gate-source voltage Vgs of the driving module 10 is the difference between the voltage of the first node N1 and the voltage of the second node N2.

[0079] In the above driving method, the reverse bias module 40 adjusts the voltage between the control end and the first end of the driving module 10 according to the reverse bias signal Vref3 between the data writing stage P3 and the light emitting stage P5 to reverse bias the driving module 10. It can be seen that the bias stage P4 can be performed between the data writing stage P3 and the light emitting stage P5.

[0080] On the basis of the above embodiment, optionally, the light-emitting stage P5 may include: controlling the first light-emitting control module 30 and the second light-emitting control module 80 to be turned on at least twice, so that the light-emitting element D is lit at least twice, thereby improving the low-frequency display effect; meanwhile, controlling the reverse bias module 40 to be turned on between at least partially adjacent two lightings, and the reverse bias module 40 adjusts the voltage between the control end and the first end of the driving module 10 according to the reverse bias signal Vref3, so that the driving module 10 is reverse biased.

[0081] In summary, the driving method of the pixel circuit provided in the embodiment of the present invention can not only reverse bias the driving module 10 between the data writing stage and the light-emitting stage to reduce the drift of the threshold voltage Vth of the driving module 10, but also reverse bias the driving module 10 multiple times within the light-emitting stage to reversely pull back the drift of the threshold voltage Vth of the driving module 10 multiple times, thereby further improving the flickering phenomenon of low-frequency display.

[0082] The pixel circuit and the driving method of the pixel circuit provided in the embodiments of the present invention belong to the same inventive concept and can thus achieve the same technical effects, and repeated descriptions will be omitted.

[0083] An embodiment of the present invention further provides a display panel, Figure 6 is a schematic diagram of a display panel provided by an embodiment of the present invention, with reference to Figure 6 The display panel may be an OLED display panel, and the display panel includes the pixel circuit provided by any of the above embodiments. The display panel and the pixel circuit provided by the embodiment of the present invention belong to the same inventive concept and can achieve the same technical effect, and the repeated contents will not be repeated.

[0084] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A pixel circuit, characterized in that: include: A driving module, comprising a control terminal, a first terminal and a second terminal, wherein the driving module is used to generate a driving current in response to a voltage at the control terminal; A data writing module, connected between the first end of the driving module and the data line, and used for transmitting the data voltage on the data line to the control end of the driving module during the data writing phase; a light emitting element, configured to emit light in response to the driving current; A first light-emitting control module and a second light-emitting control module, wherein the first light-emitting control module is connected between the first end of the driving module and the anode of the light-emitting element, and the second light-emitting control module is connected between the second end of the driving module and the first power signal line, and the first light-emitting control module and the second light-emitting control module are used to control the light-emitting element to emit light in the light-emitting stage; a reverse bias module connected between the first end of the driving module and the reverse bias signal line, used to adjust the voltage between the control end and the first end of the driving module according to the reverse bias signal on the reverse bias signal line in a biasing stage to reverse bias the driving module, and used to transmit the reverse bias signal to the driving module in a first initialization stage to initialize the control end, the first end and the second end of the driving module; The voltage at the second end of the driving module after being initialized in the first initialization stage is a reverse bias voltage; the voltage at the control end of the driving module and the first end of the driving module after being initialized in the first initialization stage is the sum of the reverse bias voltage and the threshold voltage of the driving module.

2. The pixel circuit according to claim 1, characterized in that: The reverse bias module includes a first transistor; The first end of the first transistor is connected to the first end of the driving module, the second end of the first transistor is connected to the reverse bias signal line, and the control end of the first transistor is connected to the first scanning signal line.

3. The pixel circuit according to claim 2, characterized in that: The driving module comprises a driving transistor, which is an NMOS transistor. The control end, the first end and the second end of the driving transistor serve as the control end, the first end and the second end of the driving module respectively.

4. The pixel circuit according to claim 2, characterized in that: The first transistor is an NMOS transistor.

5. The pixel circuit according to claim 1, characterized in that: The reverse bias module is used to adjust the voltage between the control terminal and the first terminal of the driving module according to the reverse bias signal between the data writing stage and the light emitting stage, so as to reverse bias the driving module; And / or, the first light-emitting control module is used to control the light-emitting element to light up at least twice within the light-emitting stage, and the reverse bias module is used to adjust the voltage between the control end and the first end of the driving module according to the reverse bias signal between at least partially adjacent two lightings to reverse bias the driving module.

6. The pixel circuit according to claim 1, characterized in that: Also included is a threshold compensation module; The threshold compensation module is connected between the second end of the driving module and the control end, and is used to compensate the threshold voltage of the driving module during the data writing phase.

7. The pixel circuit according to claim 6, characterized in that: The data writing module includes a second transistor, which is an NMOS transistor. The first end of the second transistor is connected to the first end of the driving module, the second end of the second transistor is connected to the data line, and the control end of the second transistor is connected to the second scanning signal line.

8. The pixel circuit according to claim 6, characterized in that: The threshold compensation module includes a third transistor, which is an NMOS transistor. The first end of the third transistor is connected to the second end of the driving module, the second end of the third transistor is connected to the control end of the driving module, and the control end of the third transistor is connected to the third scanning signal line.

9. The pixel circuit according to claim 1, characterized in that: Also includes a first initialization module and a storage module; The first initialization module is connected between the first end of the storage module and the first initialization signal line, and is used to transmit the first initialization signal on the first initialization signal line to the anode of the light-emitting element in the first initialization stage and / or the bias stage; The first end of the storage module is connected to the anode of the light-emitting element, and the second end of the storage module is connected to the control end of the driving module. The storage module is used to store the voltage of the control end of the driving module and to couple the voltage change of the anode of the light-emitting element to the control end of the driving module.

10. The pixel circuit according to claim 9, characterized in that: The first initialization module includes a fourth transistor, which is an NMOS transistor. The first end of the fourth transistor is connected to the first end of the storage module, the second end of the fourth transistor is connected to the first initialization signal line, and the control end of the fourth transistor is connected to the first scan signal line or the fourth scan signal line.

11. The pixel circuit according to claim 1, characterized in that: Also includes a second initialization module; The second initialization module is connected between the control end of the driving module and the second initialization signal line, and is used to transmit the second initialization signal on the second initialization signal line to the driving module in a second initialization phase performed after the first initialization phase to initialize the control end of the driving module.

12. The pixel circuit according to claim 11, characterized in that: The second initialization module includes a seventh transistor, which is an NMOS transistor. The first end of the seventh transistor is connected to the control end of the driving module, the second end of the seventh transistor is connected to the second initialization signal line, and the control end of the seventh transistor is connected to the fifth scanning signal line.

13. The pixel circuit according to claim 11, characterized in that: The second light-emitting control module includes a fifth transistor, which is an NMOS transistor. The first end of the fifth transistor is connected to the second end of the driving module, the second end of the fifth transistor is connected to the first power signal line, and the control end of the fifth transistor is connected to the light-emitting control signal line.

14. The pixel circuit according to claim 13, characterized in that: The first light-emitting control module includes a sixth transistor, which is an NMOS transistor. The first end of the sixth transistor is connected to the first end of the driving module, the second end of the sixth transistor is connected to the anode of the light-emitting element, and the control end of the sixth transistor is connected to the light-emitting control signal line.

15. A display panel, characterized in that: Comprising a pixel circuit as described in any one of claims 1-14.

16. A method for driving a pixel circuit, characterized in that: Used to drive the pixel circuit according to any one of claims 1 to 15, the method comprising: In a first initialization stage, the reverse bias module is controlled to be turned on, and the reverse bias module transmits the reverse bias signal to the driving module to initialize the control end, the first end, and the second end of the driving module; In the data writing stage, the data writing module is controlled to be turned on, and the data writing module transmits the data voltage to the driving module; In the biasing stage, the reverse biasing module is controlled to be turned on, and the reverse biasing module adjusts the voltage between the control terminal and the first terminal of the driving module according to the reverse biasing signal, so as to reverse bias the driving module; In the light-emitting stage, the first light-emitting control module is controlled to be turned on, the driving module generates the driving current in response to the voltage at its control end, and the light-emitting element emits light in response to the driving current.

17. The driving method of the pixel circuit according to claim 16, characterized in that: The lighting stage includes: The first light-emitting control module is controlled to be turned on at least twice so that the light-emitting element is lit at least twice; meanwhile, the reverse bias module is controlled to be turned on between at least partially adjacent two lightings, and the reverse bias module adjusts the voltage between the control end and the first end of the driving module according to the reverse bias signal so that the driving module is reverse biased.

18. The driving method of the pixel circuit according to claim 16, characterized in that: The pixel circuit further includes a second initialization module, wherein the second initialization module is connected between the control terminal of the driving module and a second initialization signal line; The first initialization phase and the data writing phase also include: In the second initialization stage, the second initialization module is controlled to be turned on, and the second initialization module transmits the second initialization signal to the driving module to initialize the control end of the driving module.

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