Pixel driving circuit, display panel and display device

Abstract

The present application discloses a pixel driving circuit, a display panel and a display device, wherein the pixel driving circuit includes: a driving module for providing a driving current for a light-emitting element; a first compensation module for accessing a threshold compensation signal to perform threshold compensation on the control end of the driving module in a first period of a non-luminous stage; a data writing module for accessing a first data signal and a second data signal in a second period of a non-luminous stage and a third period of a non-luminous stage, respectively; a coupling module for adjusting the control end voltage of the driving module according to the second data signal; wherein the first period of a non-luminous stage at least partially overlaps with the second period of a non-luminous stage. According to an embodiment of the present application, the threshold voltage component can be compensated and offset from the voltage component that affects the driving current through threshold compensation, thereby avoiding the threshold voltage from affecting the magnitude of the driving current and improving the display effect of the light-emitting element.

Description

Technical Field

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

[0002] At present, the display panel is usually composed of a plurality of light-emitting pixels arranged in an array, and the light-emitting pixels are composed of a pixel driving circuit and a light-emitting element. The pixel driving circuit is usually composed of a TFT (Thin Film Transistor) and a capacitor. The light-emitting element can usually include an OLED (Organic Light-Emitting Diode) or other light-emitting devices.

[0003] When the driving transistor in the pixel driving circuit is turned on, a voltage difference of a threshold voltage will be generated between the gate and the source, which will affect the driving current flowing through the driving transistor, thereby affecting the brightness of the light-emitting element. Summary of the invention

[0004] The embodiments of the present application provide a pixel driving circuit, a display panel and a display device, which can solve the technical problem that the threshold voltage of the driving transistor affects the display effect of the light-emitting element.

[0005] In a first aspect, an embodiment of the present application provides a pixel driving circuit, the pixel driving circuit comprising:

[0006] A driving module, used for providing a driving current to the light emitting element;

[0007] A first compensation module is used to access the threshold compensation signal to perform threshold compensation on the control end of the driving module during a first period of the non-light-emitting stage;

[0008] A data writing module, used for receiving the first data signal and the second data signal in the second time period and the third time period of the non-light-emitting phase respectively;

[0009] The coupling module is used to adjust the control terminal voltage of the driving module according to the second data signal; wherein,

[0010] The first time period and the second time period at least partially overlap.

[0011] In some embodiments, the pixel driving circuit includes:

[0012] An initialization module is used to receive an initialization signal during a non-light-emitting phase;

[0013] The storage module is used to receive the initialization signal in the non-light-emitting stage and maintain the control terminal voltage of the driving module in the light-emitting stage.

[0014] In some embodiments, the pixel driving circuit includes:

[0015] The second compensation module is used to access the first power supply signal to initialize the control end of the driving module in the fourth time period of the non-luminous stage; access the threshold compensation signal to perform threshold compensation on the control end of the driving module in the first time period of the non-luminous stage; wherein the fourth time period is before the first time period.

[0016] In some embodiments, during the first period of the non-light-emitting phase, the initialization module is used to connect the initialization signal to the first end of the storage module, and the second end of the storage module is connected to the control end of the driving module;

[0017] In the second period of the non-luminous phase, the data writing module is used to connect the first data signal to the first end of the coupling module, and the second end of the coupling module is connected to the control end of the driving module.

[0018] In some embodiments, the pixel driving circuit includes:

[0019] A first light-emitting control module is used to access a first power supply signal to initialize the control end of the driving module in a non-light-emitting stage;

[0020] The second light-emitting control module is used to selectively allow the light-emitting element to enter the light-emitting stage.

[0021] In some embodiments, the control end of the first light emitting control module is connected to the first light emitting control signal line, and the control end of the second light emitting control module is connected to the second light emitting control signal line;

[0022] In the fourth period of the non-luminous stage, the first luminous control module is used to receive the conduction signal of the first luminous control signal line and connect the first power supply signal to the control end of the driving module; the fourth period is before the first period;

[0023] In the non-light-emitting stage, the second light-emitting control module is used to receive a cut-off signal of the second light-emitting control signal line.

[0024] In some embodiments, a first end of the data writing module is connected to the data signal line, a second end of the data writing module is connected to the first end of the coupling module, and a control end of the data writing module is connected to the first scanning signal line;

[0025] In the second period of the non-light-emitting stage, the data writing module is used to receive the conduction signal of the first scanning signal line, and connect the first data signal output by the data signal line to the first end of the coupling module;

[0026] In the third period of the non-luminescent stage, the data writing module is used to receive the on signal of the first scanning signal line, and connect the second data signal output by the data signal line to the first end of the coupling module.

[0027] In some embodiments, the pixel driving circuit further includes:

[0028] The second initialization module is used to initialize the first electrode of the light-emitting element by accessing the initialization signal in the non-light-emitting stage.

[0029] In a second aspect, a display panel is provided. The display panel includes a light-emitting element and a pixel driving circuit connected to the light-emitting element. The pixel driving circuit is configured as the pixel driving circuit of the above aspect.

[0030] According to a third aspect, a display device is provided, which includes the display panel according to the above aspect.

[0031] Compared with the prior art, the pixel driving circuit, display panel and display device provided in the embodiment of the present application can access the threshold compensation signal to perform threshold compensation on the driving module in the first time period of the non-luminous stage, and can access the first data signal to the coupling module in the second time period to adjust the control terminal voltage of the driving module. In the overlapping period of the first time period and the second time period, the threshold compensation signal and the first data signal can jointly compensate and adjust the control terminal voltage of the driving module, so that the control terminal voltage of the driving module includes the threshold voltage component. In the third time period, the second data signal can be accessed to charge the pixel driving circuit, so that the pixel driving circuit provides a driving current for the light-emitting element in the light-emitting stage. In the threshold compensation process, the gate-source voltage difference of the driving module can be compensated as a component containing the threshold voltage, so that the threshold voltage component in the voltage component related to the driving current is offset, so as to avoid the threshold voltage affecting the magnitude of the driving current and improve the display effect of the light-emitting element. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 is a structural schematic diagram of a pixel driving circuit provided by an embodiment of the present application;

[0034] Figure 2 is a structural schematic diagram of a pixel driving circuit provided by another embodiment of the present application;

[0035] Figure 3 is a structural schematic diagram of a pixel driving circuit provided by another embodiment of the present application;

[0036] Figure 4is a structural schematic diagram of a pixel driving circuit provided in yet another embodiment of the present application;

[0037] Figure 5 is a structural schematic diagram of a pixel driving circuit provided by another embodiment of the present application;

[0038] Figure 6 is a circuit structure diagram of a pixel driving circuit provided in an embodiment of the present application;

[0039] Figure 7 is a timing diagram of a pixel driving circuit provided in an embodiment of the present application;

[0040] Figure 8 It is a schematic structural diagram of a display device according to an embodiment of the present application.

[0041] In the attached figure:

[0042] L, light-emitting element; 11, driving module; 12, first compensation module; 13, second compensation module; 14, initialization module; 15, first light-emitting control module; 16, second light-emitting control module; 17, data writing module; 18, second initialization module; 21, coupling module; 22, storage module; T1, driving transistor; T2, first compensation transistor; T3, second compensation transistor; T4, first initialization transistor; T5, first light-emitting control transistor; T6, second light-emitting control transistor; T7, data writing transistor; C1, first capacitor; Cst, storage capacitor; VDD, first power supply signal; VSS, second power supply signal; Vref1, initialization signal; Vtc, threshold compensation signal; EM1, first light-emitting control signal; EM2, second light-emitting control signal. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] It should be noted that the terms "upper", "lower", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this patent. The terms "first" and "second" are only used for the convenience of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined. In addition, terms such as "horizontal", "vertical", and "overhanging" do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] It should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] In order to illustrate the technical solution of the present application, a detailed description is given below in conjunction with specific drawings and embodiments.

[0047] At present, the display panel is usually composed of a plurality of light-emitting pixels arranged in an array, and the light-emitting pixels are composed of a pixel driving circuit and a light-emitting element. The pixel driving circuit is usually composed of a TFT (Thin Film Transistor) and a capacitor. The light-emitting element can usually include an OLED (Organic Light-Emitting Diode) or other light-emitting devices.

[0048] When the driving transistor in the pixel driving circuit is turned on, a voltage difference of the threshold voltage will be generated between the gate and the source. The threshold voltage will affect the driving current flowing through the driving transistor, thereby affecting the brightness of the light-emitting element. Therefore, in order to ensure the stability of the brightness of the light-emitting element, the threshold voltage needs to be compensated.

[0049] In the existing threshold voltage compensation method, the threshold voltage cannot be fully compensated, which will cause the driving current received by the light-emitting element to still be affected by the threshold voltage. In addition, since the subthreshold swing SS of the driving transistor is small, the impact of the threshold voltage on the driving current is more obvious at low grayscales, resulting in poor threshold compensation effect at low grayscales and uneven brightness of the displayed image.

[0050] In order to solve the above technical problems, the present application provides a pixel driving circuit, a display panel and a display device. The pixel driving circuit of an embodiment of the present application is first introduced below.

[0051] Please refer to Figure 1 , Figure 1 The schematic diagram of the structure of a pixel driving circuit provided by an embodiment of the present application is shown. The pixel driving circuit includes a driving module 11, a first compensation module 12, a data writing module 17 and a coupling module 21.

[0052] The driving module 11 can provide a driving current to the light emitting element L, and the light emitting element L can emit light under the driving current.

[0053] When the light-emitting element L performs light-emitting display, it may include a light-emitting stage and a non-light-emitting stage. In the non-light-emitting stage, the pixel driving circuit may receive a scanning signal and a data signal, and charge according to the data signal. In the light-emitting stage, the pixel driving circuit may discharge to maintain the driving module 11 turned on, so that the light-emitting element L can emit light under the drive of the first power signal VDD and the second power signal VSS.

[0054] The first compensation module 12 may connect the threshold compensation signal Vtc to the control end of the driving module 11 in the first period of the non-light-emitting stage, so as to perform threshold compensation on the control end of the driving module 11 through the threshold compensation signal Vtc.

[0055] The data writing module 17 can access the first data signal Vdata0 in the second period of the non-light-emitting stage, and access the second data signal Vdata1 in the third period of the non-light-emitting stage.

[0056] It is understandable that one end of the data writing module 17 can be connected to the data signal line. In the second period and the third period of the non-light-emitting stage, the data writing module 17 can be turned on to connect the data signal provided by the data signal line to the pixel driving circuit. The data signal line can provide a first data signal Vdata0 in the second period and a second data signal Vdata1 in the third period.

[0057] When the data writing module 17 receives the second data signal Vdata1 , the coupling module 21 can adjust the control terminal voltage of the driving module 11 according to the second data signal Vdata1 .

[0058] Among the multiple time periods of the non-luminous stage, the first time period and the second time period at least partially overlap. In the overlapping time period formed by the first time period and the second time period, the first compensation module 12 can access the threshold compensation signal Vtc to perform threshold compensation on the control end of the driving module 11. That is, in the overlapping time period, the control end voltage of the driving module 11 is adjusted by the threshold compensation signal Vtc. In the overlapping time period, the data writing module 17 can access the first data signal Vdata0. At this time, the voltage difference between the two ends of the coupling module 21 is associated with the first data signal Vdata0 and the threshold compensation signal Vtc.

[0059] It can be understood that in the first period of the non-luminous stage, the control terminal voltage of the driving module 11 can be adjusted by the threshold compensation signal Vtc. In the second period of the non-luminous stage, the voltage of one end of the coupling module 21 can be adjusted by the first data signal Vdata0. In the overlapping period of the first period and the second period of the non-luminous stage, the voltage at both ends of the coupling module 21 can be adjusted by the first data signal Vdata0 and the threshold compensation signal Vtc, so that the voltage difference at both ends of the coupling module 21 is associated with the first data signal Vdata0 and the threshold compensation signal Vtc. In the third period of the non-luminous stage, according to the corresponding luminous brightness of the light-emitting element L in the corresponding image frame, the corresponding second data signal Vdata1 can be output, and the pixel driving circuit can be charged by the second data signal Vdata1, so that the pixel driving circuit provides the corresponding driving current for the light-emitting element L in the luminous stage, so that the light-emitting element L emits light.

[0060] In different light-emitting cycles of the light-emitting element L, the signal voltage of the first data signal Vdata0 may remain consistent, and the signal voltage of the second data signal Vdata1 is related to the light-emitting brightness of the light-emitting element L in the light-emitting cycle. For example, after the target brightness of the light-emitting element L is determined according to the grayscale value of the light-emitting pixel corresponding to the light-emitting element L, the corresponding data voltage may be determined according to the target brightness and output as the second data signal Vdata1 to the pixel driving circuit corresponding to the light-emitting element L.

[0061] In the overlap period of the first period and the second period, the voltage difference between the two ends of the coupling module 21 is adjusted by the threshold compensation signal Vtc and the first data signal Vdata0. It can be understood that when the first compensation module 12 performs threshold compensation on the control end of the driving module 11 by accessing the threshold compensation signal Vtc, the compensation value is associated with the threshold voltage of the driving module 11. That is, after the threshold compensation is performed on the control end voltage of the driving module 11, the voltage component of the control end voltage includes the threshold voltage of the driving module 11.

[0062] Take the driving module 11 as an example of an N-type TFT. Figure 1 As shown, in the light-emitting stage, the driving current Ids flowing through the driving module 11 has a positive correlation with the difference (Vgs-Vth) between the gate-source voltage difference Vgs and the threshold voltage Vth of the driving module 11. The control terminal voltage of the driving module 11 is the gate voltage Vg of the driving module 11. When the gate voltage Vg contains the voltage component of the threshold voltage Vth, the difference between the gate-source voltage difference Vgs and the threshold voltage Vth can offset the voltage component of the threshold voltage, so that the driving current Ids has no correlation with the threshold voltage Vth of the driving module 11. At this time, when the second data signal Vdata1 is adjusted so that the light-emitting element L generates different light-emitting brightness in different light-emitting cycles, the actual light-emitting brightness will not be affected by the threshold voltage of the driving module 11, so that the threshold voltage compensation can be achieved, the brightness of the light-emitting element L is guaranteed to be stable, and the display effect is improved.

[0063] In this embodiment, the first compensation module 12 is set to access the threshold compensation signal Vtc in the first period of the non-light-emitting stage to perform threshold compensation on the driving module 11, and the first data signal Vdata0 can be accessed in the second period. In the overlapping period of the first period and the second period, the voltages at both ends of the coupling module 21 are adjusted by the first data signal Vdata0 and the threshold compensation signal Vtc respectively, so that the voltage difference at both ends of the coupling module 21 is associated with the first data signal Vdata0 and the threshold compensation signal Vtc. In the third period, the second data signal Vdata1 can be accessed to charge the pixel driving circuit, so that the pixel driving circuit provides a driving current for the light-emitting element L in the light-emitting stage. In the light-emitting stage, the driving current flowing through the driving module 11 has a positive correlation with the gate-source voltage difference and the threshold voltage difference of the driving module 11. Through the threshold compensation, the control terminal voltage of the driving module 11 includes the threshold voltage component, which can make the gate-source voltage difference and the threshold voltage difference result The component related to the threshold voltage can be offset, so that the driving current is not related to the threshold voltage. By performing threshold compensation on the driving module 11 , the driving current in the light emitting stage can be made to have no correlation with the threshold voltage, thereby preventing the threshold voltage from affecting the magnitude of the driving current and improving the display effect of the light emitting element L.

[0064] The pixel driving circuit and the light-emitting element L in the above embodiment can be applied to a display panel. The display panel product can be an OLED panel product. In small-sized products, LTPS (Low Temperature Poly-Silicon) transistors are usually used, and LTPS transistors are P-type transistors. In medium-sized or large-sized products, the size restrictions on transistors are relatively loose, and IGZO (Indium Gallium Zinc Oxide) transistors or other oxide transistors can be selected at this time. The above-mentioned IGZO transistors are N-type transistors.

[0065] It is understandable that when each module in the pixel driving circuit is an IGZO transistor, since the subthreshold swing of the N-type transistor is small, a small change in the gate voltage can cause a large change in the source-drain current. When the grayscale is low, the driving current is small, and the threshold voltage has a greater impact on the driving current, resulting in a poor display effect of the display panel at low grayscale. By performing threshold compensation on the control terminal voltage of the driving transistor T1 in the non-luminous stage as proposed in the above embodiment, the influence of the threshold voltage on the driving current can be eliminated, thereby improving the display effect at low grayscale.

[0066] Please refer to Figure 2 In some embodiments, the pixel driving circuit may include an initialization module 14 and a storage module 22 .

[0067] The initialization module 14 can connect the initialization signal Vref1 to the storage module 22 in the non-light-emitting stage. The first end of the storage module 22 is connected to the initialization module 14, and the second end of the storage module 22 is connected to the control end of the driving module 11. The coupling module 21 can adjust the control end voltage of the driving module 11 according to the second data signal Vdata1 in the third period of the non-light-emitting stage. At this time, the voltage of the second end of the storage module 22 changes under the input of the second data signal Vdata1. That is, in the third period, when the second data signal Vdata1 is input into the pixel driving circuit, the storage module 22 can be charged.

[0068] After the storage module 22 is charged by the second data signal Vdata1 in the third period of the non-luminous stage, it can discharge the control end of the driving module 11 in the luminous stage to maintain the control end voltage of the driving module 11 stable, so that the driving module 11 remains in the on state, thereby driving the light-emitting element L to emit light.

[0069] When the data writing module 17 is connected to the second data signal Vdata1, the coupling module 21 and the storage module 22 can be charged by the second data signal Vdata1. Since the coupling module 21 and the storage module 22 are both connected to the control end of the driving module 11, and the control end of the driving module 11 is not connected to the discharge circuit, the charge at both ends of the coupling module 21 and the storage module 22 is conserved at this time. According to the potential of one end of the coupling module 21 and the storage module 22 that is not connected to the control end of the driving module 11, the control end potential of the driving module 11 can be determined.

[0070] According to the control terminal potential of the driving module 11 and the source potential of the driving module 11, the gate-source voltage difference of the driving module 11 can be calculated, and the gate-source voltage difference includes a threshold voltage component. When calculating the difference between the gate-source voltage difference and the threshold voltage, the threshold voltage component in the gate-source voltage difference is offset with the threshold voltage, so that the calculated difference does not include the threshold voltage. The difference between the gate-source voltage difference and the threshold voltage has a positive correlation with the driving current, that is, after the threshold voltage can be partially offset in the calculated difference, the magnitude of the driving current is independent of the threshold voltage, so that the driving current received by the light-emitting element L is not affected by the threshold voltage, thereby improving the display effect of the display panel.

[0071] Please refer to Figure 3 In some embodiments, the pixel driving circuit may further include a second compensation module 13 .

[0072] The second compensation module 13 can be connected to the first power signal VDD in the fourth period of the non-luminous stage to initialize the control end of the driving module 11 through the first power signal VDD. At this time, the control end voltage of the driving module 11 is the signal voltage of the first power signal VDD.

[0073] In the second stage of the non-luminous stage, the second compensation module 13 can be turned on together with the first compensation module 12 to output the threshold compensation signal Vtc to the control end of the driving module 11 through the first compensation module 12, the driving module 11 and the second compensation module 13, and the control end of the driving module 11 is threshold compensated by the threshold compensation signal Vtc.

[0074] The fourth period is before the first period. The fourth period may be an initialization period in the non-luminous phase. That is, in a single non-luminous phase, the second compensation module 13 may first initialize the control terminal voltage of the driving module 11 to the signal voltage of the first power signal VDD, and then access the threshold compensation signal Vtc together with the first compensation module 12 to adjust the control terminal voltage of the driving module 11 to the voltage after threshold compensation.

[0075] It is understandable that the first compensation module 12 can connect the threshold compensation signal Vtc to the first end of the driving module 11, and the second compensation module 13 can conduct the control end of the driving module 11 with the second end. When the driving module 11 is an N-type transistor, the voltage difference between the control end voltage and the first end voltage of the driving module 11 in the on state should be greater than or equal to the threshold voltage Vth of the driving module 11. That is, when the first compensation module 12 introduces the threshold compensation signal Vtc into the first end of the driving module 11, the control end voltage of the driving module 11 can be changed from the signal voltage of the first power supply signal VDD to the voltage after threshold compensation, and the voltage after threshold compensation is the sum of the threshold compensation signal Vtc and the threshold voltage Vth, that is, (Vtc+Vth). It is understandable that the control end voltage of the driving module 11 after the threshold compensation mentioned above contains the component of the threshold voltage Vth.

[0076] In some embodiments, in the first period of the non-light-emitting stage, the initialization module 14 may connect the initialization signal Vref1 to the first end of the storage module 22 , and the second end of the storage module 22 is connected to the control end of the driving module 11 .

[0077] In the second period of the non-light-emitting stage, the data writing module 17 can connect the first data signal Vdata0 to the first end of the coupling module 21 , and the second end of the coupling module 21 is connected to the control end of the driving module 11 .

[0078] In a single non-light-emitting phase, the first period is in front and the second period is in the back, and there is an overlap period between the first period and the second period.

[0079] In the non-coincidence period of the first period, the initialization module 14 can connect the initialization signal Vref1 to one end of the storage module 22, the first compensation module 12 can connect the threshold compensation signal Vtc to the control end of the driving module 11, the data writing module 17 is not turned on, and the first data signal Vdata0 is not connected. At this time, the voltage at the first end of the storage module 22 is the signal voltage of the initialization signal Vref1, and the voltage at the second end of the storage module 22 is the control end voltage of the driving module 11, and the control end voltage is the sum (Vtc+Vth) of the threshold compensation signal Vtc and the threshold voltage Vth.

[0080] During the overlapping period between the first time period and the second time period, the initialization module 14 and the first compensation module 12 continue to remain in the on state. At this time, the data writing module 17 is turned on and the first data signal Vdata0 is written into the first end of the coupling module 21. At this time, the voltage at the first end of the coupling module 21 is the signal voltage of the first data signal Vdata0.

[0081] In the third period of the non-light-emitting stage, the data signal provided by the data signal line is adjusted from the first data signal Vdata0 to the second data signal Vdata1. At this time, the voltage at the first terminal of the coupling module 21 changes from the signal voltage of the first data signal Vdata0 to the signal voltage of the second data signal Vdata1. Since the control terminal of the driving module 11 is respectively connected to the second terminal of the coupling module 21 and the second terminal of the storage module 22, and the control terminal of the driving module 11 is not connected to the discharge circuit, the voltage at the control terminal of the driving module 11 can be calculated according to the change amplitude of the voltage at the first terminal of the coupling module 21.

[0082] When the non-luminous phase changes to the luminous phase, the voltage difference between the control terminal voltage and the source voltage of the driving module 11 is the same as that at the end of the third period of the non-luminous phase. Since the control terminal voltage of the driving module 11 includes a threshold voltage component, when calculating the gate-source voltage difference of the driving module 11, the threshold voltage component can be offset during the calculation process, so that the calculated voltage component affecting the driving current does not include the threshold voltage, thereby achieving threshold voltage compensation in the non-luminous phase.

[0083] Please refer to Figure 4 In some embodiments, the pixel driving circuit may further include a first light emitting control module 15 and a second light emitting control module 16 .

[0084] The first light-emitting control module 15 can connect the first power signal VDD to initialize the control end of the driving module 11 in the non-light-emitting stage, so that the control end voltage of the driving module 11 is initialized to the signal voltage of the first power signal VDD. The first power signal VDD can be connected to the control end of the driving module 11 through the first light-emitting control module 15 and the second compensation module 13.

[0085] The second light-emitting control module 16 can selectively allow the light-emitting element L to enter the light-emitting stage. When the second light-emitting control module 16 and the first light-emitting control module 15 are both turned on, the first power signal VDD can be connected to the first electrode of the light-emitting element L through the first light-emitting control module 15, the driving module 11 and the second light-emitting control module 16 in sequence, and the light-emitting element L can emit light under the drive of the first power signal VDD and the second power signal VSS.

[0086] It can be understood that when the first light-emitting control module 15 and the second light-emitting control module 16 are both turned on, the first electrode of the light-emitting element L can be connected to the first power supply signal VDD and emit light. Therefore, at any time in the non-light-emitting stage, at least one of the first light-emitting control module 15 and the second light-emitting control module 16 is in a disconnected state to prevent the light-emitting element L from emitting light by mistake in the non-light-emitting stage.

[0087] The first light-emitting control module 15 is turned on in the fourth period of the non-light-emitting stage, i.e., the initialization stage, and the first power supply signal VDD is connected to the control end of the driving module 11 for initialization. In order to prevent the light-emitting element L from emitting light by mistake in the fourth period, the second light-emitting control module 16 needs to remain in the off state in the fourth period. That is, the first light-emitting control module 15 and the second light-emitting control module 16 can be respectively turned on and off by different light-emitting control signals to prevent the first light-emitting control module 15 and the second light-emitting control module 16 from being turned on at the same time in the non-light-emitting stage, causing the light-emitting element L to emit light by mistake.

[0088] In some embodiments, the control end of the first light emitting control module 15 may be connected to the first light emitting control signal line, and the control end of the second light emitting control module 16 may be connected to the second light emitting control signal line.

[0089] In the fourth period of the non-light-emitting stage, the first light-emitting control module 15 can receive the on-signal output by the first light-emitting control signal line, and connect the first power signal VDD to the control end of the driving module 11 to initialize the control end voltage of the driving module 11 to the signal voltage of the first power signal VDD. It can be understood that the above initialization process should be located before the threshold compensation of the threshold compensation signal Vtc, that is, the fourth period is located before the first period.

[0090] In the non-luminous phase, the second luminous control module 16 can receive the cutoff signal output by the second luminous control signal line and maintain the disconnected state, so that in the complete non-luminous phase, the first electrode of the luminous element L does not receive the first power signal VDD.

[0091] In some embodiments, the first end of the data writing module 17 can be connected to the data signal line, the second end of the data writing module 17 can be connected to the first end of the coupling module 21, and the control end of the data writing module 17 can be connected to the first scanning signal line.

[0092] In the second time period of the non-luminous stage, the data writing module 17 can receive the turn-on signal output by the first scanning signal line and turn on. At this time, the first data signal Vdata0 output by the data signal line can be connected to the first end of the coupling module 21 through the data writing module 17 to adjust the first end voltage of the coupling module 21 to the signal voltage of the first data signal Vdata0.

[0093] In the third time period of the non-luminous stage, the data writing module 17 can receive the turn-on signal of the first scanning signal line and turn on. At this time, the second data signal Vdata1 output by the data signal line can be connected to the first end of the coupling module 21 through the data writing module 17 to adjust the first end voltage of the coupling module 21 to the signal voltage of the second data signal Vdata1.

[0094] Please refer to Figure 4 In some embodiments, the first end of the initialization module 14 may be connected to the initialization signal line, and the second end of the initialization module 14 may be connected to the first end of the storage module 22 and the first electrode of the light-emitting element L, respectively. When the initialization module 14 is disconnected, the initialization signal Vref1 is not connected to the storage module 22 and the first electrode of the light-emitting element L. When the initialization module 14 is turned on, the initialization signal Vref1 may adjust the voltage of the first end of the storage module 22 to the signal voltage of the initialization signal Vref1, and initialize the voltage of the first electrode of the light-emitting element L.

[0095] In this embodiment, since the first terminal of the storage module 22 is connected to the first electrode of the light-emitting element L, in the light-emitting stage, the voltage of the first electrode of the light-emitting element L is relatively close to the voltage of the first terminal of the storage module 22. Since the voltage of the first electrode of the light-emitting element L is close to the source voltage of the driving module 11, the voltage of the first terminal of the storage module 22 is also relatively consistent with the source voltage of the driving module 11. The voltage of the second terminal of the storage module 22 is the control terminal voltage of the driving module 11. At this time, the storage module 22 can maintain the gate-source voltage difference of the driving module 11 greater than or equal to the threshold voltage of the driving module 11 through discharge, so that the driving module 11 maintains the on state.

[0096] Please refer to Figure 5 In some embodiments, the pixel driving circuit may further include a second initialization module 18 .

[0097] One end of the second initialization module 18 is connected to the initialization signal line, and the other end is connected to the first electrode of the light emitting element L. When the second initialization module 18 is turned on, the initialization signal Vref1 can initialize the first electrode of the light emitting element L.

[0098] One end of the initialization module 14 is connected to the initialization signal line, and the other end is connected to the first end of the storage module 22. That is, the initialization module 14 can introduce the initialization signal Vref1 into the storage module 22, and the second initialization module 18 can introduce the initialization signal Vref1 into the first electrode of the light emitting element L.

[0099] As an optional implementation, the driving module 11, the data writing module 17, the first compensation module 12, the second compensation module 13, the initialization module 14, the first light emitting control module 15 and the second light emitting control module 16 can be thin film transistors TFT. For example, they can be N-channel IGZO TFTs. The coupling module 21 and the storage module 22 can be the first capacitor C1 and the storage capacitor Cst respectively. The connection method of each transistor and capacitor is as shown in the attached figure. Figure 6As shown, the pixel driving circuit may include a driving transistor T1, a first compensation transistor T2, a second compensation transistor T3, a first initialization transistor T4, a first light emission control transistor T5, a second light emission control transistor T6, a data writing transistor T7, a second initialization transistor T8, a first capacitor C1 and a storage capacitor Cst. It can be understood that the above modules may also be other types of oxide transistors, which are not limited here.

[0100] like Figure 7 As shown, the non-luminous stage at least includes a fourth period t4, a first period t1, a second period t2 and a third period t3, and the luminous stage may include a fifth period t5.

[0101] The fourth period t4 is an initialization stage, and the first electrode of the light emitting element L and the gate of the driving transistor T1 are initialized in this period.

[0102] The first period t1 is a threshold compensation stage, and the threshold compensation signal Vtc can be connected to the source of the driving transistor T1. At this time, the driving transistor T1 is in an on state, and the gate voltage of the driving transistor T1 is the sum of the source voltage and the threshold voltage, that is, (Vtc+Vth).

[0103] The second period t2 is a compensation and writing coexistence stage. The threshold compensation signal Vtc can compensate the gate voltage of the driving transistor T1 to (Vtc+Vth), the first data signal Vdata0 can increase the first terminal voltage of the first capacitor C1 to Vdata0, and the initialization signal Vref1 can adjust the first terminal voltage of the storage capacitor Cst to Vref1.

[0104] It can be understood that there is an overlap period ta between the first period t1 and the second period t2. During the period ta, the threshold compensation signal Vtc and the first data signal Vdata0 can respectively adjust the voltage across the first capacitor C1.

[0105] The third period t3 is the data writing stage, and the second data signal Vdata1 can adjust the first terminal voltage of the first capacitor C1 from Vdata0 to Vdata1. Since the gate voltage of the driving transistor T1 is not connected to the discharge circuit, the charge amount across the first capacitor C1 and the storage capacitor Cst is conserved. According to the change in the first terminal voltage of the first capacitor C1 and the first terminal voltage of the storage capacitor Cst, the gate voltage of the driving transistor T1 can be determined, and the gate voltage determination formula can be:

[0106] Vg=Vtc+Vth-(Vdata0+Vref1)+(Vdata1*C1+Vref1*Cst) / (C1+Cst);

[0107] After determining the gate voltage of the driving transistor T1, the gate-source voltage difference of the driving transistor T1 can be calculated according to the gate voltage and the source power supply. The gate-source voltage difference can be:

[0108] Vga=Vg-Va=Vtc+Vth-Vdata0+(Vdata1-Vref1)*C1 / (C1+Cst)-Vref1;

[0109] After the third period of the non-light-emitting stage ends, the first light-emitting control signal EM1 and the second light-emitting control signal EM2 can output a turn-on signal to the corresponding light-emitting control transistor to enter the light-emitting stage t5.

[0110] At the starting node of the light-emitting stage t5, if the driving transistor T1 operates in the saturated conduction region, the gate-source voltage difference of the driving transistor T1 is consistent with the gate-source voltage difference in the third period. At this time, the driving current flowing through the driving transistor T1 has a positive correlation with the difference between the gate-source voltage difference and the threshold voltage, that is:

[0111] Ids=1 / 2*μ*W / L*(Vgs-Vth)^2∝(Vgs-Vth)^2;

[0112] Wherein, μ is the mobility of the driving transistor T1, and W / L is the width-to-length ratio of the driving transistor T1. That is, when the parameters of the driving transistor T1 are determined, the driving current has a positive correlation with the difference between the gate-source voltage difference and the threshold voltage.

[0113] When the second light emitting control transistor T6 is turned on, the potential at point a is consistent with the potential at point s, that is, Vgs=Vga. At this time, it can be obtained:

[0114] (Vgs-Vth)=(Vga-Vth)=[Vtc-Vdata0+(Vdata1-Vref1)*C1 / (C1+Cst)-Vref1].

[0115] From the above analysis, it can be seen that the magnitude of the driving current flowing through the driving transistor T1 is correlated with the first data signal Vdata0, the second data signal Vdata1, the initialization signal Vref1, the threshold compensation signal Vtc, the first capacitor C1, and the storage capacitor Cst, but has nothing to do with the magnitude of the threshold voltage Vth. At this time, the threshold voltage will not affect the magnitude of the driving current received by the light-emitting element L, so that the threshold voltage compensation in the non-light-emitting stage can be achieved, and the display effect of the light-emitting element L can be improved.

[0116] Based on the above pixel driving circuit embodiments, the embodiments of the present application also protect a display panel and a display device.

[0117] See also Figure 8 , Figure 8 It is a schematic diagram of a display device provided in the present application. The display device may include a display panel. The display device may be at least one of a wearable device, a camera, a mobile phone, a tablet computer, a display screen, a television, and a vehicle-mounted display terminal.

[0118] The display panel includes the pixel driving circuit and the light-emitting element provided in the above embodiment, and the display device includes the display panel, so the display device and the display panel have all the beneficial effects of the above display panel.

[0119] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A pixel driving circuit, characterized in that: The pixel driving circuit comprises: A driving module, used for providing a driving current to the light emitting element; A first compensation module, used for accessing a threshold compensation signal to perform threshold compensation on the control end of the driving module during a first period of a non-luminous phase; A data writing module, used for receiving the first data signal and the second data signal in the second time period and the third time period of the non-light-emitting phase respectively; A coupling module, used for adjusting a control terminal voltage of the driving module according to the second data signal; A storage module, used for receiving an initialization signal in a non-light-emitting stage and maintaining a control terminal voltage of the driving module in a light-emitting stage; An initialization module is used to receive an initialization signal during a non-light-emitting phase; The second compensation module is used to access the first power supply signal to initialize the control end of the driving module in the fourth period of the non-luminous stage; access the threshold compensation signal to perform threshold compensation on the control end of the driving module in the first period of the non-luminous stage; wherein the fourth period is before the first period; wherein, The first time period and the second time period at least partially overlap; In the first period of the non-light-emitting stage, the initialization module is used to connect the initialization signal to the first end of the storage module, and the second end of the storage module is connected to the control end of the driving module; In the second period of the non-light-emitting stage, the data writing module is used to connect the first data signal to the first end of the coupling module, and the second end of the coupling module is connected to the control end of the driving module.

2. The pixel driving circuit according to claim 1, characterized in that: The pixel driving circuit comprises: A first light-emitting control module, used for initializing the control end of the driving module by accessing a first power signal in a non-light-emitting stage; The second light-emitting control module is used to selectively allow the light-emitting element to enter the light-emitting stage.

3. The pixel driving circuit according to claim 2, characterized in that: The control end of the first light-emitting control module is connected to the first light-emitting control signal line, and the control end of the second light-emitting control module is connected to the second light-emitting control signal line; In a fourth period of the non-light-emitting stage, the first light-emitting control module is used to receive a conduction signal of the first light-emitting control signal line, and connect the first power supply signal to the control end of the driving module; The fourth time period is before the first time period; In the non-light-emitting stage, the second light-emitting control module is used to receive a cut-off signal of the second light-emitting control signal line.

4. The pixel driving circuit according to claim 3, characterized in that: The first end of the data writing module is connected to the data signal line, the second end of the data writing module is connected to the first end of the coupling module, and the control end of the data writing module is connected to the first scanning signal line; In the second period of the non-light-emitting stage, the data writing module is used to receive a turn-on signal of the first scanning signal line, and connect the first data signal output by the data signal line to the first end of the coupling module; In the third period of the non-light-emitting stage, the data writing module is used to receive the turn-on signal of the first scanning signal line, and connect the second data signal output by the data signal line to the first end of the coupling module.

5. The pixel driving circuit according to claim 1, characterized in that: The pixel driving circuit further includes: The second initialization module is used to initialize the first electrode of the light-emitting element by accessing an initialization signal in a non-light-emitting stage.

6. A display panel, characterized in that: The display panel includes a light emitting element and a pixel driving circuit connected to the light emitting element, and the pixel driving circuit is configured as the pixel driving circuit according to any one of claims 1 to 5.

7. A display device, characterized in that: The display device comprises the display panel as claimed in claim 6.

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