Pixel driving circuit and driving method thereof, display panel and display device

Abstract

Embodiments of the present application disclose a pixel driving circuit and a driving method thereof, a display panel and a display device. The pixel driving circuit comprises a driving module and a switching module. The driving module is configured to output a driving current according to a data voltage. The switching module is connected in series between the driving module and a light emitting module. A control terminal of the switching module is connected to a fixed voltage. The fixed voltage satisfies that the switching module is turned on when the driving module is turned on. By connecting the switching module in series between the driving module and the light emitting module, the leakage of the driving module can be reduced, and the light emitting module can be prevented from being lightened. By connecting the fixed voltage to the control terminal of the switching module, the switching module can be turned on when the driving module is turned on. Without affecting the driving of the light emitting module by the driving module, the potential of the first terminal of the light emitting device caused by the aging of the light emitting device can be improved, the potential of the control terminal of the driving module can be affected, and thus the influence of the aging of the light emitting device on the light emitting brightness can be reduced, and the display effect can be improved.

Description

Technical Field

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

[0002] With the development of display technology, users have increasingly higher requirements for the display effect of display devices.

[0003] Display devices include multiple pixel driving circuits. Due to manufacturing limitations, the leakage current level of the driving transistors may exceed the turn-on current requirements of the light-emitting devices, causing some light-emitting devices to appear lit up even in a completely black screen. Furthermore, aging of the light-emitting devices can lead to an increase in their turn-on voltage. Because of the parasitic capacitive coupling between the gate and drain of the driving transistor, the gate potential of the driving transistor will also fluctuate significantly, reducing the current of the driving transistor. This results in insufficient brightness after the light-emitting devices age.

[0004] The aforementioned leakage issues in the driving transistors and the insufficient brightness caused by the aging of the light-emitting devices will both affect the display effect and reduce the user experience. Summary of the Invention

[0005] This invention provides a pixel driving circuit and driving method thereof, a display panel and a display device, to limit the leakage current of the driving transistor, reduce the impact of aging of the light-emitting device on the brightness of light emission, and improve the display effect.

[0006] According to one aspect of the present invention, a pixel driving circuit is provided, comprising: a driving module and a switching module, wherein the driving module is used to output a driving current; The switch module is connected in series between the driver module and the light-emitting module, and the control terminal of the switch module is connected to a fixed voltage; wherein, the fixed voltage is such that the switch module is turned on when the driver module is turned on.

[0007] Optionally, the switch module is connected in series between the first end of the drive module and the light-emitting module, and the second end of the light-emitting module is electrically connected to the first power supply line; the control end of the switch module is electrically connected to the first power supply line, or the control end of the switch module is grounded.

[0008] Optionally, the pixel driving circuit also includes a reset module, which is electrically connected to the first terminal of the light-emitting module and is used to transmit a reset voltage to the first terminal of the light-emitting module during the reset phase.

[0009] Optionally, the control terminal of the switch module is electrically connected to the reset signal line, which is used to transmit the reset voltage.

[0010] Optionally, the pixel driving circuit further includes a data writing module, a storage module, and a light-emitting control module. The data writing module is electrically connected to the driving module and is used to write data voltage to the driving module during the data writing phase. The light-emitting control module is connected in series between the second power line and the first end of the driving module, and the switch module is connected in series between the second end of the driving module and the first end of the light-emitting module. The light-emitting control module is used to turn off during the data writing phase and turn on during the light-emitting phase. One end of the storage module is electrically connected to the second power line, and the other end of the storage module is electrically connected to the control terminal of the driving module.

[0011] Optionally, the storage module includes a first capacitor and a second capacitor. The first terminal of the first capacitor is electrically connected to the second power line, the second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor, and the second terminal of the second capacitor is electrically connected to the control terminal of the drive module. The first terminal of the light-emitting control module is electrically connected to the second power line, and the second terminal of the light-emitting control module is electrically connected to the first terminal of the second capacitor. The light-emitting control module is also used to conduct during the reset phase. The data writing module is also used to transmit the initialization voltage to the control terminal of the drive module during the reset phase. The reset phase is performed before the data writing phase. The reset module is also used to turn on during the self-discharge phase so that the drive module discharges through the switch module and the reset module according to the voltage difference between its own control terminal and its own first terminal until the voltage difference between the control terminal of the drive module and its own first terminal meets the turn-off condition of the drive module. The self-discharge phase occurs between the reset phase and the data writing phase; the data writing module and the light-emitting control module are also used to turn off during the self-discharge phase.

[0012] Optionally, the ratio of the capacitance value of the first capacitor to the set capacitance value is equal to the back-gate effect modulation coefficient of the driving module, and the set capacitance value is equal to the sum of the capacitance values ​​of the first capacitor and the second capacitor.

[0013] Optionally, the driving module includes a driving transistor, and the switching module includes a first transistor; the driving transistor and the first transistor are connected in series between the second power line and the light-emitting module; the gate of the driving transistor serves as the control terminal of the driving module, and the gate of the first transistor serves as the control terminal of the switching module.

[0014] According to another aspect of the present invention, a driving method for a pixel driving circuit is provided, applicable to a pixel driving circuit in any embodiment of the present invention, the driving method comprising: During the light-emitting phase, the driving module generates a driving current, and the switching module responds to the applied fixed voltage and turns on, outputting the driving current to the light-emitting module.

[0015] Optionally, the pixel driving circuit may also include a reset module, and the driving method may also include: During the reset phase, the reset module responds to the second scan signal and turns on, transmitting a reset voltage to the first terminal of the light-emitting module; the reset phase occurs before the light-emitting phase.

[0016] Optionally, the pixel driving circuit also includes a data writing module, a storage module, and a light emission control module. The data writing module is electrically connected to the driving module, and the light emission control module is connected in series between the second power line and the first end of the driving module. The storage module includes a first capacitor and a second capacitor. The first end of the first capacitor is electrically connected to the second power line, the second end of the first capacitor is electrically connected to the first end of the second capacitor, and the second end of the second capacitor is electrically connected to the control end of the driving module. The driving method also includes: During the reset phase, the light-emitting control module responds to the light-emitting control signal and conducts to transmit the second power supply voltage to the first terminal of the second capacitor; the data writing module responds to the first scan signal and conducts to transmit the initialization voltage to the control terminal of the drive module. During the data writing phase, the data writing module is turned on in response to the first scan signal and writes data voltage to the drive module; the reset phase is performed before the data writing phase. During the self-discharge phase, the data writing module turns off in response to the first scan signal, and the light emission control module turns off in response to the light emission control signal; the reset module turns on in response to the second scan signal, and the drive module turns on according to the voltage difference between its own control terminal and its own first terminal, and discharges through the switch module and the reset module until the voltage difference between the control terminal of the drive module and its own first terminal meets the turn-off condition. The self-discharge phase occurs between the reset phase and the data writing phase.

[0017] According to another aspect of the present invention, a display panel is provided, including a plurality of pixel driving circuits according to any embodiment of the present invention.

[0018] According to another aspect of the present invention, a display device is provided, including a display panel according to any embodiment of the present invention.

[0019] The pixel driving circuit, driving method, and display device of this invention reduce leakage current in the driving module and reduce the possibility of the light-emitting module idling by connecting a switching module in series between the driving module and the light-emitting module. By connecting a fixed voltage to the control terminal of the switching module, the switching module can be turned on when the driving module is turned on. Without affecting the driving module's ability to drive the light-emitting module to emit light, this invention can mitigate the impact of the potential increase at the first terminal of the light-emitting module caused by the aging of the light-emitting device on the potential of the control terminal of the driving module. This reduces the impact of the aging of the light-emitting device on the driving current generated by the driving module, thereby reducing the impact of the aging of the light-emitting device on the brightness and improving the display effect.

[0020] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a pixel driving circuit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention; Figure 7 This is a driving timing diagram of a pixel driving circuit provided in an embodiment of the present invention; Figure 8 This is a schematic diagram showing the conduction status of each module in the pixel drive circuit during the reset phase. Figure 9 This is a schematic diagram showing the conduction status of each module in the pixel driving circuit during the self-discharge stage. Figure 10 This is a schematic diagram showing the conduction status of each module in the pixel driving circuit during the data writing stage; Figure 11 This is a schematic diagram showing the conduction status of each module in the pixel driving circuit during the light-emitting stage; Figure 12 This is a flowchart of a pixel driving circuit driving method provided in an embodiment of the present invention; Figure 13 This is a flowchart of another driving method for a pixel driving circuit provided in an embodiment of the present invention; Figure 14 This is a schematic diagram of the structure of a display panel provided in an embodiment of the present invention; Figure 15This is a schematic diagram of the structure of a display device provided in an embodiment of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] This invention provides a pixel driving circuit. Figure 1 This is a schematic diagram of a pixel driving circuit provided in an embodiment of the present invention, for reference. Figure 1 The pixel driving circuit includes a driving module 120 and a switching module 130. The driving module 120 is used to output driving current. The switching module 130 is connected in series between the driving module 120 and the light-emitting module 200. The control terminal of the switching module 130 is connected to a fixed voltage V0. The fixed voltage V0 satisfies the condition that the switching module 130 is turned on when the driving module 120 is turned on.

[0026] Optionally, the driving module 120 includes a driving transistor, the gate of which serves as the control terminal G of the driving module 120, the first electrode of which serves as the first terminal of the driving module 120, and the second electrode of which serves as the second terminal of the driving module 120. Optionally, the first electrode of the driving transistor is the source, and the second electrode of the driving transistor is the drain.

[0027] The driving module 120 is the core current control module in the pixel driving circuit, connected in series between the power supply and the light-emitting module 200. The driving module 120 can generate a driving current based on the voltage difference between its control terminal and its first terminal, thereby driving the light-emitting module 200 to emit light. The brightness of the light-emitting module 200 is positively correlated with the magnitude of the driving current. The light-emitting module 200 can be an organic light-emitting device, such as an organic light-emitting diode (OLED), specifically an active matrix organic light-emitting diode (AMOLED). The light-emitting module 200 can also be an inorganic light-emitting device, such as a micro light-emitting diode (Micro-LED).

[0028] The pixel driving circuit also includes a switch module 130, which is connected in series with the driving module 120. There is at least one switch module 130; when there are at least two switch modules 130, both switch modules 130 are connected in series with the driving module 120. The switch module 130 is connected in series between the driving module 120 and the light-emitting module 200. Thus, the switch module 130 can limit leakage current in the driving module 120. Compared to the case where the driving module 120 is directly connected to the light-emitting module 200, this reduces the voltage difference between the first and second terminals of the driving module 120, thereby reducing leakage current in the driving module 120, reducing the possibility of the light-emitting module 200 idling, and improving the display effect.

[0029] Furthermore, in this embodiment of the invention, the control terminal of the switch module 130 is connected to a fixed voltage V0, meaning the potential of the control terminal of the switch module 130 will not change. The magnitude of the fixed voltage V0 is such that the switch module 130 is turned on when the drive module 120 is turned on. Thus, the setting of the switch module 130 will not affect the drive module 120's ability to drive the light-emitting module 200 to emit light. As described in the background art, aging of the light-emitting device in the light-emitting module 200 causes the potential of the first terminal of the light-emitting module 200 to rise. When the drive module 120 is directly connected to the light-emitting module 200, the potential of the control terminal G of the drive module 120 will be raised due to the coupling fluctuation of the parasitic capacitance of the drive transistor, causing a voltage change at the control terminal G of the drive module 120. The amount of voltage change at the control terminal G of the drive module 120 is equal to the amount of voltage change at the first terminal of the light-emitting module 200, resulting in a decrease in current generation efficiency and causing the brightness to be substandard after the light-emitting device ages. In this embodiment of the invention, by setting the switch module 130, the second terminal of the drive module 120 is not directly connected to the light-emitting module 200. Furthermore, since the first terminal of the switch module 130 is connected to the second terminal of the drive module 120, and the control terminal of the switch module 130 is connected to a fixed voltage V0, the potential of the second terminal of the drive module 120 is also limited by the fixed voltage V0 of the control terminal of the switch module 130. For example, if the switch module 130 includes a P-type transistor, the minimum voltage of the second terminal of the drive module 120 is equal to the difference between the control terminal voltage (i.e., the fixed voltage V0) of the switch module 130 and the threshold voltage of the transistor included in the switch module 130. Thus, during the non-light-emitting phase of the light-emitting module 200, the second terminal of the drive module 120 and the first terminal of the light-emitting module 200 can have different voltages. For example, by setting the magnitude of the fixed voltage V0, during the non-light-emitting phase, the voltage of the second terminal of the drive module 120 can be higher than the voltage of the first terminal of the light-emitting module 200. During the light-emitting stage, the driving module 120 and the switching module 130 are turned on. The voltage at the first terminal of the switching module 130 is the same as the voltage at the second terminal of the switching module 130. Correspondingly, the voltage at the second terminal of the driving module 120 is equal to the voltage at the first terminal of the light-emitting module 200. Therefore, from the non-light-emitting stage to the light-emitting stage, the voltage change at the first terminal of the switching module 130 is less than the voltage change at the second terminal of the switching module 130. In other words, the voltage change at the second terminal of the driving module 120 is lower than the voltage change at the first terminal of the light-emitting module 200. Consequently, the voltage change at the control terminal of the driving module 120 caused by the voltage change at the second terminal of the driving module 120 will decrease. This reduces the impact of the increased potential at the first terminal of the light-emitting module 200 on the voltage at the control terminal of the driving module 120 when transitioning from the non-light-emitting stage to the light-emitting stage. This improves the effect of aging of the light-emitting device on the brightness, ensures current generation efficiency, increases the brightness of the light-emitting module 200, and thus enhances the display effect.

[0030] It should be noted that the fixed voltage V0 connected to the control terminal of the switch module 130 is sufficient to ensure that the switch module 130 is turned on when the drive module 120 is turned on. When the drive module 120 is turned off, the switch module 130 can be turned on or off. This embodiment of the invention does not limit this.

[0031] The pixel driving circuit of this embodiment reduces leakage current in the driving module and minimizes the possibility of the light-emitting module idling by connecting a switch module in series between the driving module and the light-emitting module. By applying a fixed voltage to the control terminal of the switch module, the switch module can be turned on when the driving module is on. Without affecting the driving module's ability to illuminate the light-emitting module, this circuit mitigates the impact of the potential rise at the first terminal of the light-emitting module caused by aging of the light-emitting device on the potential of the control terminal of the driving module. This reduces the impact of light-emitting device aging on the driving current generated by the driving module, thereby reducing the impact of light-emitting device aging on the brightness and improving the display effect.

[0032] Figure 2 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention, for reference. Figure 2 Optionally, the switch module 130 is connected in series between the drive module 120 and the first end of the light-emitting module 200, and the second end of the light-emitting module 200 is electrically connected to the first power line VSS.

[0033] In this light-emitting module 200, one of the first end and the second end of the light-emitting module 200 is the anode of the light-emitting device, and the other is the cathode of the light-emitting device. Figure 2 The diagram shows a case where the first end of the light-emitting module 200 is the anode of the light-emitting device, and the second end of the light-emitting module 200 is the cathode of the light-emitting device.

[0034] The first power line VSS is used to transmit a first power supply voltage, which is a fixed voltage. In some embodiments, the control terminal of the switch module 130 is electrically connected to the first power line VSS. This configuration eliminates the need for additional signal lines due to the addition of the switch module 130, reducing the number of signal lines in the display device, simplifying wiring, and improving the density of the pixel driving circuit, thereby increasing the resolution of the display device.

[0035] Continue to refer to Figure 2 The pixel driving circuit also includes a data writing module 110 and a storage module 140; the data writing module 110 is electrically connected to the driving module 120 and is used to write data voltage to the driving module 120; the storage module 140 is electrically connected to the control terminal G of the driving module 120 and is used to store the voltage of the control terminal G of the driving module 120.

[0036] The data writing module 110 may include a switching device. For example... Figure 2As shown, the data writing module 110 can be connected to the control terminal G of the drive module 120. In other embodiments, the data writing module 110 can be connected to the first terminal of the drive module 120. Optionally, the control terminal of the data writing module 110 is electrically connected to the first scan line WS, the first terminal of the data writing module 110 is connected to the data line DATA, and the second terminal of the data writing module 110 is connected to the drive module 120. The data line DATA transmits data voltage during the data writing phase. The first scan line WS is used to transmit a first scan signal. During the data writing phase, the data writing module 110 is turned on in response to the first scan signal, and the data writing module 110 writes data voltage to the drive module 120. That is, the data writing module 110 is used to write data voltage to the drive module 120 during the data writing phase. For example, for Figure 2 The pixel driving circuit shown has a data writing module 110 writing data voltage to the control terminal G of the driving module 120.

[0037] The storage module 140 may include at least one capacitor for storing the voltage of the control terminal G of the drive module 120.

[0038] Continue to refer to Figure 2 In some embodiments, the switching module 130 includes a first transistor T1, and the driving module 120 includes a driving transistor TD. The driving transistor TD and the first transistor T1 are connected in series between the second power line VDD and the light-emitting module 200. The gate of the driving transistor TD serves as the control terminal G of the driving module 120, and the gate of the first transistor T1 serves as the control terminal of the switching module 130.

[0039] Specifically, both the data writing module 110 and the driving module 120 in the pixel driving circuit include transistor devices, and the setting switch module 130 includes a first transistor T1, which can be fabricated simultaneously with other transistor devices in the pixel driving circuit without adding process steps. The first transistor T1 is connected in series between the second terminal of the driving transistor TD and the light-emitting module 200. In addition to limiting the leakage current of the driving transistor TD, it can reduce the impact of light-emitting device aging on the gate potential of the driving transistor TD, effectively suppressing the problem of limited current generation capability of the driving transistor TD due to light-emitting device aging, and improving the luminous brightness of the light-emitting device.

[0040] The first transistor T1 can be either a P-type transistor or an N-type transistor. Taking the first transistor T1 as a P-type transistor as an example, the first power supply voltage on the first power supply line VSS is a low-level voltage.

[0041] Figure 3 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention, for reference. Figure 3In some embodiments, the control terminal of the switch module 130 is grounded to GND. In this case, the potential of the control terminal of the switch module 130 is 0, which is applicable when the first transistor of the switch module 130 is a P-type transistor.

[0042] Figure 4 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention, for reference. Figure 4 Optionally, the pixel driving circuit also includes a reset module 150, which is electrically connected to the first end of the light-emitting module 200 and is used to transmit a reset voltage to the first end of the light-emitting module 200 during the reset phase.

[0043] The reset module 150 may include a switching device. Optionally, the control terminal of the reset module 150 may be electrically connected to the second scan line AZ, which is used to transmit the second scan signal. The first terminal of the reset module 150 is electrically connected to the reset signal line VAR, and the second terminal of the reset module 150 is electrically connected to the first terminal of the light-emitting module 200. The reset signal line VAR is used to transmit the reset voltage. The reset voltage is a fixed voltage, and the voltage difference between the reset voltage and the first power supply voltage is less than the turn-on voltage of the light-emitting module 200, so that after the reset by the reset module 150, the light-emitting module 200 is in a black state, ensuring a purer black state current. During the reset phase, the reset module 150 is turned on in response to the second scan signal, which can clear the residual charge on the first terminal of the light-emitting module 200 in the previous frame and avoid the influence of the residual charge on the first terminal of the light-emitting module 200 in the previous frame on the display effect.

[0044] In some embodiments, the control terminal of the switch module 130 is connected to the reset signal line VAR, which is used to transmit the reset voltage, i.e., the fixed voltage is equal to the reset voltage. This configuration eliminates the need for additional signal lines due to the addition of the switch module 130, reducing the number of signal lines in the display device, simplifying wiring, and improving the density of the pixel driving circuit, thereby increasing the resolution of the display device.

[0045] Figure 4In the pixel driving circuit shown, during the non-light-emitting stage of the light-emitting module 200, the potential of the first terminal of the light-emitting module 200 is the reset voltage, denoted as Vref. When the switching module 130 includes a P-type transistor, the lowest potential of the second terminal of the driving module 120 is Vref-Vth, where Vref-Vth>Vref. Assuming that during the light-emitting stage, the voltage at the second terminal of the driving module 120 and the voltage at the first terminal of the light-emitting module 200 are both V1, then from the non-light-emitting stage to the light-emitting stage, the voltage change at the first terminal of the switching module 130 is less than the voltage change at the second terminal of the switching module 130. That is, the voltage change at the second terminal of the driving module 120 is lower than the voltage change at the first terminal of the light-emitting module 200. Correspondingly, the voltage change at the control terminal of the driving module 120 caused by the voltage change at the second terminal of the driving module 120 will decrease. This reduces the impact of the increased potential at the first terminal of the light-emitting module 200 on the voltage at the control terminal of the driving module 120 when transitioning from the non-light-emitting stage to the light-emitting stage, thereby mitigating the impact of aging of the light-emitting device on the brightness.

[0046] It should be noted that, Figure 3 In the pixel driving circuit shown, the ground (GND) voltage is greater than the reset voltage. Therefore, relative to the control terminal of the switch module 130 connected to the reset signal line, the minimum voltage at the second terminal of the drive module 120 is larger. This further reduces the voltage change at the first terminal of the switch module 130 from the non-emitting stage to the emitting stage compared to the voltage change at the second terminal. Consequently, the voltage change at the control terminal of the drive module 120 caused by the voltage change at the second terminal of the drive module 120 will be further reduced, further mitigating the impact of aging of the light-emitting device on the brightness.

[0047] Figure 5 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention, for reference. Figure 5 Optionally, the pixel driving circuit also includes an emissive control module 160, which is connected in series between the second power line VDD and the first end of the driving module 120. A switch module 130 is connected in series between the second end of the driving module 120 and the first end of the emissive module 200. The emissive control module 160 is used to turn off during the data writing phase and turn on during the emissive phase. One end of the storage module 140 is electrically connected to the second power line VDD, and the other end of the storage module 140 is electrically connected to the control terminal G of the driving module 120.

[0048] The light-emitting control module 160 may also include a switching device. Optionally, the control terminal of the light-emitting control module 160 is electrically connected to the light-emitting control line DS. The light-emitting control line DS is used to transmit light-emitting control signals. During the light-emitting phase, the light-emitting control module 160 responds to the light-emitting control signal and conducts, connecting the first terminal of the drive module 120 with the second power line VDD. This allows the drive module 120 to generate a drive current based on the voltage of its control terminal G and its first terminal, and transmits this current to the light-emitting module 200 through the switching module 130. The light-emitting control module 160 can control the duty cycle of the light-emitting time according to the light-emitting control signal to improve the low grayscale display effect. Specifically, the brightness of the light-emitting module 200 is related to the magnitude of the drive current and the duty cycle of the light-emitting time. At low grayscale levels, when the voltage change at the control terminal of the drive module 120 is very small, the drive current may change significantly, making it impossible to achieve the brightness corresponding to some low grayscale levels simply by adjusting the drive current. By adjusting the duty cycle of the light emission control signal, the light emission time duty cycle of the light emission module 200 can be adjusted, that is, the light emission duration of the light emission module 200 can be adjusted. Thus, the light emission brightness can be adjusted by the duty cycle of the light emission time and the driving current, so that low grayscale can be better unfolded, thereby improving the display effect under low grayscale.

[0049] The first end of the storage module 140 is connected to the second power line VDD, and the second end of the storage module 140 is connected to the control terminal G of the drive module 120. The storage module 140 can store the voltage of the control terminal of the drive module 120. For example, during the light-emitting stage, it stores the voltage difference between the control terminal G and the first end of the drive module 120. During the light-emitting stage, it keeps the voltage difference between the control terminal G and the first end of the drive module 120 stable, ensuring that the drive current generated by the drive module 120 during the light-emitting stage is stable and ensuring a good display effect.

[0050] Figure 6 This is a schematic diagram of another pixel driving circuit provided in an embodiment of the present invention, for reference. Figure 6The storage module 140 includes a first capacitor Cp and a second capacitor Cst. A first terminal of the first capacitor Cp is electrically connected to the second power line VDD, and a second terminal of the first capacitor Cp is electrically connected to the first terminal of the second capacitor Cst. The second terminal of the second capacitor Cst is electrically connected to the control terminal G of the driving module 120. The first terminal of the light-emitting control module 160 is electrically connected to the second power line VDD, and the second terminal of the light-emitting control module 160 is electrically connected to the first terminal of the second capacitor Cst. The light-emitting control module 160 is also used to conduct during the reset phase. The data writing module 110 is also used to write data to the driving module during the reset phase. The control terminal G of drive module 120 transmits the initialization voltage; the reset phase occurs before the data writing phase; the reset module 150 is also used to turn on during the self-discharge phase, so that drive module 120 discharges through switch module 130 and reset module 150 according to the voltage difference between its own control terminal and its own first terminal, until the voltage difference between the control terminal G and the first terminal S of drive module 120 meets the turn-off condition of drive module 120; the self-discharge phase occurs between the reset phase and the data writing phase; data writing module 110 and light-emitting control module 160 are also used to turn off during the self-discharge phase. Switch module 130 is connected in series between the second terminal D of drive module 120 and light-emitting module 200.

[0051] Specifically, during the reset phase, the data line DATA transmits the initialization voltage, the data writing module 110 is turned on, and the initialization voltage is transmitted to the control terminal G of the driver module 120, thereby initializing the control terminal G of the driver module 120. Thus, there is no need to set up an additional initialization module in the pixel driver circuit to initialize the control terminal G of the driver module 120; that is, the data writing module 110 can be reused as an initialization module. This reduces the number of modules included in the pixel driver circuit, and consequently reduces the number of circuit elements included in the pixel driver circuit, thereby reducing the topological area of ​​the pixel driver circuit, increasing the pixel density in the display device, and achieving higher resolution.

[0052] During the self-discharge phase, the reset module 150 is turned on in response to the second scan signal, and the data writing module 110 and the light-emitting control module 160 are turned off. The first terminal of the second capacitor Cst discharges through the first terminal S of the driving module 120, through the driving module 120, the switching module 130 and the reset module 150 to the reset signal line VAR until the voltage difference between the control terminal G of the driving module 120 and the first terminal S of the driving module 120 meets the turn-off condition of the driving module 120, that is, the voltage difference between the gate and the first terminal of the driving transistor TD is equal to the threshold voltage of the driving transistor TD. This achieves the capture of the threshold voltage of the driving transistor TD during the self-discharge phase to compensate for the threshold voltage of the driving transistor TD, so that the driving current generated by the driving transistor TD is independent of the threshold voltage of the driving transistor TD. This avoids the problem of poor display uniformity caused by the different threshold voltages of the driving transistor TD in different pixel driving circuits, thereby improving display uniformity and further improving the display effect.

[0053] In this embodiment, the storage module 140 includes a first capacitor Cp and a second capacitor Cst connected in series. The common connection terminal of the first capacitor Cp and the second capacitor Cst is connected to the second terminal of the light-emitting control module 160. When the light-emitting control module 160 is turned on during the initialization phase, the voltage stored in the second capacitor Cst after the initialization phase is the difference between the second power supply voltage and the initialization voltage. The second power supply voltage is the voltage on the second power line VDD. When the light-emitting control module 160 is turned off during the self-discharge phase, both the control terminal G of the driving module 120 and the first terminal S of the driving module 120 (i.e., the two ends of the second capacitor Cst) are floating. During the self-discharge process of the first terminal S of the driving module 120, the potential of the control terminal G of the driving module 120 changes accordingly. When the light-emitting control module 160 is turned off during the data writing phase, the first terminal S of the driving module 120 is floating, i.e., the common connection terminal of the first capacitor Cp and the second capacitor Cst is floating. This causes the potential of the first terminal S of the driving module 120 to change with the potential of the control terminal G of the driving module 120. In this process, the threshold voltage of the driving transistor TD is compensated by utilizing the substrate bias modulation response, thereby further improving display uniformity and enhancing the display effect. Furthermore, the pixel driving circuit of this embodiment includes a smaller number of modules, resulting in fewer circuit components and a smaller topological area, making it suitable for high-resolution display devices.

[0054] The following explanation will focus on the specific working process of the pixel driving circuit.

[0055] Figure 7 This is a driving timing diagram of a pixel driving circuit provided in an embodiment of the present invention. This driving timing can be applied to driving... Figure 6 The pixel driving circuit shown is as follows: Figure 6As shown, the data writing module 110 includes a second transistor T2, the light-emitting control module 160 includes a third transistor T3, the reset module 150 includes a fourth transistor T4, and the light-emitting module 200 includes a light-emitting diode, as an example. Optionally, the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, and the driving transistor TD can be P-type transistors or N-type transistors; this embodiment of the invention does not impose specific limitations here. Figure 6 The driving timing shown corresponds to the case where the first transistor T1, the second transistor T2, the third transistor T3, and the driving transistor TD are all P-type transistors, and the fourth transistor T4 is an N-type transistor. Accordingly, the active level in the gate control signals of the first transistor T1, the second transistor T2, the third transistor T3, and the driving transistor TD is low, and the inactive level is high; the active level in the gate control signal of the fourth transistor T4 is high, and the inactive level is low. Here, the active level is the level that turns the transistor on, and the inactive level is the level that turns the transistor off. (Reference) Figure 6 and Figure 7 The operation of the pixel driving circuit includes a reset phase p1, a self-discharge phase p2, a data writing phase p3, and a light emission phase p4.

[0056] Figure 8 This is a schematic diagram showing the conduction status of each module in the pixel drive circuit during the reset phase. (Refer to...) Figure 7 and Figure 8 During the reset phase p1, the first scan signal on the first scan line WS is low, and the second transistor T2 is turned on; the second scan signal on the second scan line AZ is high, and the fourth transistor T4 is turned on; the light emission control signal on the light emission control line DS is low, and the third transistor T3 is turned on. The signal transmitted on the data line DATA is the initialization voltage Vini. At this time, the voltage at the first end of the second capacitor Cst is the second power supply voltage, and the voltage at the second end is the initialization voltage Vini. At this time, the voltage difference across the second capacitor Cst is ELVDD-Vini, where ELVDD is the second power supply voltage on the second power supply line VDD. Since the fourth transistor T4 is turned on at this time, the driving transistor TD can release charge to the reset signal line VAR through the first transistor T1 and the fourth transistor T4. The first end of the light emission module 200 can also release charge to the reset signal line VAR through the fourth transistor T4.

[0057] Figure 9 This is a schematic diagram showing the conduction status of each module in the pixel drive circuit during the self-discharge phase. (Refer to...) Figure 7 and Figure 9During the self-discharge phase p2, the first scan signal on the first scan line WS is high, and the second transistor T2 is turned off; the second scan signal on the second scan line AZ is high, and the fourth transistor T4 is turned on; the light emission control signal on the light emission control line DS changes from low to high, and when the light emission control signal is high, the third transistor T3 is turned off. During this phase, the first terminal of the second capacitor Cst (i.e., the upper plate of the second capacitor Cst) discharges through the first terminal of the driving transistor TD (i.e., the first terminal S of the driving module 120, a floating point), through the driving transistor TD, the first transistor T1, and the reset module 150 to the reset signal line VAR. When the voltage difference between the gate and the first terminal of the driving transistor TD equals the threshold voltage of the driving transistor TD, the driving transistor TD is turned off, and the self-discharge process ends. At this time, the voltage stored in the second capacitor Cst is the threshold voltage of the driving transistor TD. The substrate of the driving transistor TD can be connected to the second power supply line VDD. Due to the substrate bias modulation effect, the threshold voltage changes. The changed threshold voltage can be calculated using the following formula: |Vth_eff|=a×(ELVDD-VS)+|Vth|, where a is the back-gate effect modulation coefficient, Vth_eff is the threshold voltage after the shift, and Vth is the threshold voltage before the shift. Therefore, after the self-discharge process ends, the first gate potential of the driving transistor TD is VS=ELVDD–(ELVDD-Vini-|Vth|) / a; correspondingly, the gate potential of the driving transistor TD is VG=Vini-(ELVDD-Vini-|Vth|) / a.

[0058] Figure 10 This is a schematic diagram showing the conduction status of each module in the pixel drive circuit during the data writing phase. (Refer to...) Figure 7 and Figure 10During the data writing phase p3, the first scan signal on the first scan line WS is low, and the second transistor T2 is turned on; the second scan signal on the second scan line AZ is high, and the fourth transistor T4 is turned on; the light emission control signal on the light emission control line DS is high, and the third transistor T3 is turned off. The signal transmitted on the data line DATA is the data voltage VDATA. The data voltage VDATA is written to the gate of the driving transistor TD via the second transistor T2, that is, the second terminal of the second capacitor Cst. Since the upper plate of the driving transistor TD (the first terminal of the driving transistor TD) is still floating, the voltage of the first terminal of the driving transistor TD increases due to the increase in the gate voltage of the driving transistor TD. The change is related to the ratio of the second capacitor Cst to the first capacitor Cp. Assuming that the series ratio of the first capacitor Cp to the second capacitor Cst is b=Cp / (Cst+Cp), the voltage change of the first terminal of the driving transistor is (1-b)×ΔVG, where ΔVG represents the change in the gate voltage of the driving transistor TD, ΔVG=VDATA-Vini+(ELVDD-Vini-|Vth|) / a. At this time, the change in the first electrode potential of the driving transistor TD is ΔVS = (1-b) × [VDATA-Vini + (ELVDD-Vini-|Vth|) / a], VS = ELVDD–(ELVDD-Vini-|Vth|) / a + ΔVS = ELVDD–b × (ELVDD-Vini-|Vth|) / a + (1-b) × (VDATA-Vini).

[0059] Figure 11 This is a schematic diagram showing the conduction status of each module in the pixel driving circuit during the light-emitting stage. (Refer to...) Figure 7 and Figure 11 During the light-emitting stage p4, the first scan signal on the first scan line WS is high, and the second transistor T2 is off; the second scan signal on the second scan line AZ is low, and the fourth transistor T4 is off; the light-emitting control signal on the light-emitting control line DS is low, and the third transistor T3 is on. At this time, the potential of the first terminal of the driving transistor TD returns to the second power supply voltage ELVDD, and the gate of the driving transistor TD becomes floating. Since the potential of the first terminal of the driving transistor TD is pulled high, the potential of the gate of the driving transistor TD will also be pulled high accordingly. At this time, the gate potential of the driving transistor TD is equal to VG=b×VDATA+(b / a)×ELVDD+[1-(b / a)–b]×Vini–(b / a)×|Vth|. Therefore, during the light-emitting stage p4, the voltage difference between the gate and the first terminal of the driving transistor TD is... Vgs = b × VDATA + ((b / a) - 1) × ELVDD + (1 - (b / a) - b) × Vini – (b / a) × |Vth|. Since the driving transistor TD is a P-type transistor, and the threshold voltage Vth of the driving crystal TD is < 0, then Vgs = b × VDATA + ((b / a) - 1) × ELVDD + (1 - (b / a) - b) × Vini + (b / a) × Vth.

[0060] Optionally, the ratio of the capacitance value of the first capacitor Cp to the set capacitance value is equal to the back-gate effect modulation coefficient of the driving module 120, and the set capacitance value is equal to the sum of the capacitance values ​​of the first capacitor Cp and the second capacitor Cst.

[0061] According to Vgs=b×VDATA+((b / a)-1)×ELVDD+(1-(b / a)-b)×Vini+(b / a)×Vth, by designing the capacitance values ​​of the first capacitor Cp and the second capacitor Cst, when b=a, Vgs=b×VDATA+(-b)×Vini+Vth. The driving current generated by the driving transistor is related to Vgs-Vth, that is, related to b×Vdata+(-b)×Vini, and is independent of the threshold voltage of the driving transistor TD. This allows the threshold voltage of the driving transistor TD to be fully compensated, avoiding the influence of threshold voltage fluctuations of the driving transistor on the generated current, and making the output driving current more accurate.

[0062] This invention also provides a driving method for a pixel driving circuit. Figure 12 This is a flowchart of a pixel driving circuit driving method provided in an embodiment of the present invention, see reference. Figure 12 The driving methods include: S220. During the light-emitting stage, the driving module generates a driving current, and the switching module responds to the fixed voltage applied and turns on, outputting the driving current to the light-emitting module.

[0063] Optionally, before S220, there is also S210, in which the data writing module responds to the first scan signal to turn on and writes data voltage to the drive module.

[0064] Specifically, during the data writing phase, the first scan signal provided to the control terminal of the data writing module is at an active level, causing the data writing module to turn on in response to the first scan signal. The drive current of the driving transistor is generated based on the data voltage.

[0065] The driving method of the pixel driving circuit in this embodiment can be applied to the pixel driving circuit of any of the above embodiments of the present invention, and has the beneficial effects of the pixel driving circuit of any of the embodiments of the present invention, which will not be described again here.

[0066] refer to Figure 6In some embodiments, the pixel driving circuit further includes a reset module 150; the driving method further includes: during the reset phase, the reset module is turned on in response to the second scan signal and transmits a reset voltage to the first end of the light-emitting module; the reset phase is performed before the light-emitting phase.

[0067] Specifically, during the reset phase, the second scan signal provided to the control terminal of the reset module is at an active level, which enables the reset module to conduct.

[0068] The pixel driving circuit also includes a data writing module 110, a storage module 140, and a light emission control module 160; the data writing module 110 is electrically connected to the driving module 120, and the light emission control module 160 is connected in series between the second power line VDD and the first terminal S of the driving module 120; the storage module 140 includes a first capacitor Cp and a second capacitor Cst, the first terminal of the first capacitor Cp is electrically connected to the second power line VDD, the second terminal of the first capacitor Cp is electrically connected to the first terminal of the second capacitor Cst, and the second terminal of the second capacitor Cst is electrically connected to the control terminal G of the driving module 120.

[0069] Figure 13 This is a flowchart of another pixel driving circuit driving method provided in an embodiment of the present invention, see reference. Figure 13 This driving method is applicable to drivers Figure 6 The pixel driving circuit shown may optionally include the following driving methods: S310. During the reset phase, the reset module responds to the second scan signal and conducts a reset voltage to the first terminal of the light-emitting module; the light-emitting control module responds to the light-emitting control signal and conducts a second power supply voltage to the first terminal of the second capacitor; the data writing module responds to the first scan signal and conducts an initialization voltage to the control terminal of the drive module.

[0070] Specifically, during the reset phase, the second scan signal provided to the control terminal of the reset module is at an active level, causing the reset module to conduct. The light emission control signal provided to the control terminal of the light emission control module is at an active level, causing the light emission control module to conduct. The first scan signal provided to the control terminal of the data writing module is at an active level, causing the data writing module to conduct in response to the first scan signal and transmit the initialization voltage to the control terminal of the drive module.

[0071] S320. During the self-discharge phase, the data writing module turns off in response to the first scan signal, and the light emission control module turns off in response to the light emission control signal; the reset module turns on in response to the second scan signal, and the drive module turns on according to the voltage difference between its own control terminal and its own first terminal, and discharges through the switch module and the reset module until the voltage difference between the control terminal of the drive module and the first terminal of the drive module meets the turn-off condition.

[0072] The reset phase occurs before the data writing phase; the self-discharge phase occurs between the reset phase and the data writing phase.

[0073] Specifically, during the self-discharge phase, the second scan signal provided to the control terminal of the reset module is at an active level, causing the reset module to conduct. The first scan signal provided to the control terminal of the data writing module is at an inactive level, causing the data writing module to turn off. The light emission control signal provided to the control terminal of the light emission control module is at an inactive level, causing the light emission control module to turn off.

[0074] S330. During the data writing phase, the data writing module responds to the first scan signal and turns on to write data voltage to the control terminal of the drive module.

[0075] In addition, during the data writing phase, the light emission control module turns off in response to the light emission control signal, and the reset module turns on in response to the second scan signal.

[0076] S340. During the light-emitting stage, the driving module generates a driving current based on the data voltage, and the switching module responds to the fixed voltage input and turns on, outputting the driving current to the light-emitting module.

[0077] Specifically, during the light-emitting phase, the light-emitting control signal provided to the light-emitting control module is at an active level, and the light-emitting control module turns on in response to the light-emitting control signal. The first scan signal provided to the control terminal of the data writing module is at an inactive level, and the data writing module turns off in response to the first scan signal. The second scan signal provided to the control terminal of the reset module is at an inactive level, and the reset module turns off in response to the second scan signal.

[0078] This invention also provides a display panel. Figure 14 This is a schematic diagram of the structure of a display panel provided in an embodiment of the present invention, for reference. Figure 14 The display panel 10 includes a plurality of pixel driving circuits 100 according to any embodiment of the present invention, and has the beneficial effects of the pixel driving circuits of any embodiment of the present invention, which will not be described again here.

[0079] This invention also provides a display device. Figure 15 This is a schematic diagram of the structure of a display device provided in an embodiment of the present invention, for reference. Figure 15 The display device 20 includes a display panel as described in the foregoing embodiments. The display device may be, but is not limited to, a mobile phone, tablet computer, laptop computer, desktop monitor, television, and head-mounted display devices such as AR (Augmented Reality) glasses, Virtual Reality (VR) glasses, and Mixed Reality (MR) glasses.

[0080] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0081] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A pixel driving circuit, characterized in that, include: A drive module and a switch module, wherein the drive module is used to output drive current; The switch module is connected in series between the driving module and the light-emitting module, and the control terminal of the switch module is connected to a fixed voltage; wherein, the fixed voltage satisfies the condition that the switch module is turned on when the driving module is turned on.

2. The pixel driving circuit according to claim 1, characterized in that, The switch module is connected in series between the first end of the drive module and the light-emitting module, and the second end of the light-emitting module is electrically connected to the first power line; the control end of the switch module is electrically connected to the first power line, or the control end of the switch module is grounded.

3. The pixel driving circuit according to claim 1, characterized in that, It also includes a reset module, which is electrically connected to the first terminal of the light-emitting module and is used to transmit a reset voltage to the first terminal of the light-emitting module during the reset phase.

4. The pixel driving circuit according to claim 3, characterized in that, The control terminal of the switch module is electrically connected to the reset signal line, which is used to transmit the reset voltage.

5. The pixel driving circuit according to claim 3, characterized in that, It also includes a data writing module, a storage module, and a light-emitting control module. The data writing module is electrically connected to the driving module and is used to write data voltage to the driving module during the data writing phase. The light-emitting control module is connected in series between the second power line and the first terminal of the driving module, and the switch module is connected in series between the second terminal of the driving module and the first terminal of the light-emitting module. The light-emitting control module is used to turn off during the data writing phase and turn on during the light-emitting phase. One end of the storage module is electrically connected to the second power line, and the other end of the storage module is electrically connected to the control terminal of the drive module.

6. The pixel driving circuit according to claim 5, characterized in that, The storage module includes a first capacitor and a second capacitor. A first terminal of the first capacitor is electrically connected to the second power line, a second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor, and a second terminal of the second capacitor is electrically connected to the control terminal of the drive module. The first terminal of the light-emitting control module is electrically connected to the second power line, and the second terminal of the light-emitting control module is electrically connected to the first terminal of the second capacitor. The light-emitting control module is also used to turn on during the reset phase. The data writing module is also used to transmit an initialization voltage to the control terminal of the drive module during the reset phase. The reset phase is performed before the data writing phase. The reset module is also used to turn on during the self-discharge phase, so that the drive module discharges through the switch module and the reset module according to the voltage difference between its own control terminal and its own first terminal, until the voltage difference between the control terminal of the drive module and the first terminal of the drive module meets the turn-off condition of the drive module. The self-discharge phase occurs between the reset phase and the data writing phase; the data writing module and the light emission control module are also used to turn off during the self-discharge phase.

7. The pixel driving circuit according to claim 6, characterized in that, The ratio of the capacitance value of the first capacitor to the set capacitance value is equal to the back-gate effect modulation coefficient of the driving module, and the set capacitance value is equal to the sum of the capacitance values ​​of the first capacitor and the second capacitor.

8. The pixel driving circuit according to any one of claims 1-7, characterized in that, The driving module includes a driving transistor, and the switching module includes a first transistor; the driving transistor and the first transistor are connected in series between the second power line and the light-emitting module; the gate of the driving transistor serves as the control terminal of the driving module, and the gate of the first transistor serves as the control terminal of the switching module.

9. A driving method for a pixel driving circuit, characterized in that, The driving method, applied to the pixel driving circuit according to any one of claims 1-8, comprises: During the light-emitting phase, the driving module generates a driving current, and the switching module responds to the fixed voltage applied and turns on, outputting the driving current to the light-emitting module.

10. The driving method for the pixel driving circuit according to claim 9, characterized in that, The pixel driving circuit further includes a reset module, and the driving method further includes: During the reset phase, the reset module is turned on in response to the second scan signal and transmits a reset voltage to the first terminal of the light-emitting module; the reset phase is performed before the light-emitting phase.

11. The driving method for the pixel driving circuit according to claim 10, characterized in that, The pixel driving circuit further includes a data writing module, a storage module, and a light emission control module. The data writing module is electrically connected to the driving module, and the light emission control module is connected in series between the second power line and the first terminal of the driving module. The storage module includes a first capacitor and a second capacitor. The first terminal of the first capacitor is electrically connected to the second power line, the second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor, and the second terminal of the second capacitor is electrically connected to the control terminal of the driving module. The driving method further includes: During the reset phase, the light-emitting control module responds to the light-emitting control signal and conducts to transmit the second power supply voltage to the first terminal of the second capacitor; the data writing module responds to the first scan signal and conducts to transmit the initialization voltage to the control terminal of the driving module. During the data writing phase, the data writing module is turned on in response to the first scan signal and writes data voltage to the driving module; the reset phase is performed before the data writing phase. During the self-discharge phase, the data writing module turns off in response to the first scan signal, and the light emission control module turns off in response to the light emission control signal; the reset module turns on in response to the second scan signal, and the driving module turns on according to the voltage difference between its own control terminal and its own first terminal, and discharges through the switch module and the reset module until the voltage difference between the control terminal of the driving module and its own first terminal meets the turn-off condition. The self-discharge phase occurs between the reset phase and the data writing phase.

12. A display panel, characterized in that, It includes the pixel driving circuits as described in any one of claims 1-8.

13. A display device, characterized in that, Includes the display panel as described in claim 12.

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