A pixel driving circuit and its application

Abstract

The present invention discloses a pixel driving circuit and its application. The pixel driving circuit includes a pixel light-emitting unit, a driving unit, a data writing unit, a data storage unit, a threshold storage unit, and a control unit. The control unit responds to a control signal, enabling the threshold storage unit to store the threshold voltage of the driving unit into the threshold storage unit during a threshold compensation phase; and during a light-emitting phase, enabling the threshold voltage stored in the threshold storage unit to cancel out the threshold voltage of the driving unit. Through the pixel driving circuit and its application provided by the present invention, the display quality of a display panel can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of display, and particularly relates to a pixel driving circuit and its application. Background Art

[0002] The display non-uniformity caused by the unstable current of the light-emitting device can be solved by corresponding compensation techniques. And the compensation techniques can be divided into internal compensation and external compensation. Internal compensation refers to a method of compensating by using a sub-circuit constructed by TFT (Thin Film Transistor) inside the pixel, while external compensation refers to sensing the electrical or optical characteristics of the pixel through an external driving circuit or device and then performing compensation.

[0003] Further studying the driving circuit of the light-emitting device, the brightness uniformity problem of the light-emitting device is mainly related to the threshold voltage of the corresponding driving transistor. The manufacturing process differences of the driving transistors and the temperature fluctuations of the environment where they are located may both cause the drift change of the threshold voltage of the driving transistors, thereby causing the non-uniform light emission of the light-emitting devices, and further affecting the gray level and image quality of the entire display panel.

[0004] Therefore, finding an efficient and reliable technical solution for compensating the threshold voltage of the driving transistor is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a pixel driving circuit and its application, aiming to solve the problem of non-uniform light emission caused by the threshold voltage of the driving transistor.

[0006] To solve the above technical problems, the present invention is realized through the following technical solutions:

[0007] The present invention provides a pixel driving circuit, including a pixel light-emitting unit, a driving unit, a data writing unit, a data storage unit, a threshold storage unit, and a control unit:

[0008] The control unit responds to a threshold storage control signal, and is used to electrically connect the first end of the threshold storage unit to the first end and the control end of the driving unit, electrically connect the second end of the threshold storage unit to the second end of the driving unit, and make the voltage difference of the threshold storage unit equal to the threshold voltage of the driving unit;

[0009] The control unit responds to a data storage control signal, and is used to electrically connect the first end of the data storage unit to the control end of the driving unit and the data writing unit, electrically connect the second end of the data storage unit to the second end of the driving unit, and make the data storage unit store a data voltage; and

[0010] The control unit responds to the light emission control signal to electrically connect the first end of the threshold storage unit to the second end of the data storage unit, electrically connect the second end of the threshold storage unit to the second end of the driving unit, and electrically connect the first end of the data storage unit to the control end of the driving unit, and electrically connect the first end of the driving unit to the pixel light-emitting unit.

[0011] In the above pixel driving circuit, by setting the threshold storage unit, a voltage is stored in the threshold storage unit before the pixel light-emitting unit is lit, and the stored voltage value is equal to the threshold voltage of the driving unit. When the pixel light-emitting unit is lit, the voltage in the threshold storage unit cancels out the threshold voltage of the driving unit, effectively realizing the threshold voltage compensation of the driving unit, making the driving current of the pixel light-emitting unit independent of the threshold voltage of the corresponding driving unit, effectively avoiding the influence of various factors such as inherent process structure differences or environmental temperature fluctuations that affect the threshold voltage of the driving transistor on the driving current, and improving the display quality.

[0012] Optionally, the control unit also responds to the initial control signal to electrically connect the second end of the threshold storage unit to the second end of the driving unit and the second power supply, and electrically connect the first end of the threshold storage unit to the data writing unit.

[0013] In the initialization stage, the threshold storage unit can be charged, so that the driving unit conducts in the threshold compensation stage.

[0014] Optionally, the control unit includes a first transistor, a second transistor, a third transistor, a fourth transistor, and a fifth transistor;

[0015] The first end of the first transistor is electrically connected to the second end of the pixel light-emitting unit, and the second end of the first transistor is electrically connected to the first end of the driving unit;

[0016] The first end of the second transistor is electrically connected to the second end of the data storage unit and the first end of the threshold storage unit, and the second end of the second transistor is electrically connected to the first end of the driving unit;

[0017] The first end of the third transistor is electrically connected to the second end of the threshold storage unit, and the second end of the third transistor is electrically connected to the second end of the driving unit;

[0018] The first end of the fourth transistor is electrically connected to the first end of the threshold storage unit and the second end of the data storage unit, and the second end of the fourth transistor is electrically connected to the control end of the driving unit and the data writing unit;

[0019] The first terminal of the fifth transistor is electrically connected to the control terminal of the driving unit and the data writing unit, and the second terminal of the fifth transistor is electrically connected to the first terminal of the driving unit.

[0020] The above-mentioned first transistor can control whether the pixel light-emitting unit is lit, thereby avoiding the pixel light-emitting unit from being accidentally lit in other stages except the light-emitting stage. The second transistor can prevent the data storage unit from being connected to the pixel driving circuit during the initialization stage and the threshold compensation stage. The third transistor can prevent the threshold storage unit from being connected to the circuit during the data storage stage. The fourth transistor shorts the data storage unit during the initialization stage and the threshold compensation stage to avoid incorrect data writing. The fifth transistor connects the threshold storage unit to the first terminal of the driving unit during the threshold compensation stage to ensure that the voltage value stored in the threshold storage unit is equal to the threshold voltage of the driving unit.

[0021] Optionally, in response to the initial control signal, the control unit disconnects the first terminal and the second terminal of the first transistor, disconnects the first terminal and the second terminal of the second transistor, conducts the first terminal and the second terminal of the third transistor, conducts the first terminal and the second terminal of the fourth transistor, and disconnects the first terminal and the second terminal of the fifth transistor.

[0022] Optionally, in response to the threshold storage control signal, the control unit disconnects the first terminal and the second terminal of the first transistor, disconnects the first terminal and the second terminal of the second transistor, conducts the first terminal and the second terminal of the third transistor, conducts the first terminal and the second terminal of the fourth transistor, and conducts the first terminal and the second terminal of the fifth transistor.

[0023] Optionally, in response to the data storage control signal, the control unit disconnects the first terminal and the second terminal of the first transistor, conducts the first terminal and the second terminal of the second transistor, disconnects the first terminal and the second terminal of the third transistor, disconnects the first terminal and the second terminal of the fourth transistor, and disconnects the first terminal and the second terminal of the fifth transistor.

[0024] Optionally, in response to the light-emitting control signal, the control unit conducts the first terminal and the second terminal of the first transistor, disconnects the first terminal and the second terminal of the second transistor, conducts the first terminal and the second terminal of the third transistor, disconnects the first terminal and the second terminal of the fourth transistor, and disconnects the first terminal and the second terminal of the fifth transistor.

[0025] Optionally, the second terminal of the driving unit is electrically connected to the second power supply, the control terminal of the driving unit is electrically connected to the first terminal of the data writing unit, and the first terminal of the pixel light-emitting unit is electrically connected to the first power supply.

[0026] Based on the same inventive concept, the present application further provides a display panel, including the pixel driving circuit described above.

[0027] Based on the same inventive concept, the present application further provides an electronic device, including the display panel described above.

[0028] For the above-mentioned display panel and electronic device, since the same pixel driving circuit is provided, the driving current of the pixel light-emitting unit is independent of the threshold voltage of the corresponding driving unit, improving the grayscale and brightness control accuracy of the display panel and the display quality of the display panel.

[0029] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic diagram of a pixel driving circuit.

[0032] Figure 2 It is a block diagram of a pixel driving circuit of the present invention.

[0033] Figure 3 It is a schematic diagram of a pixel driving circuit in the present invention.

[0034] Figure 4 For the present invention Figure 3 It is a driving timing state diagram of the pixel driving circuit.

[0035] Figure 5 For the present invention Figure 3 It is a schematic diagram of the pixel driving circuit in the initialization stage.

[0036] Figure 6 For the present invention Figure 3 It is a schematic diagram of the pixel driving circuit in the threshold compensation stage.

[0037] Figure 7 For the present invention Figure 3 It is a schematic diagram of the pixel driving circuit in the data storage stage.

[0038] Figure 8 For the present invention Figure 3 It is a schematic diagram of the pixel driving circuit in the light-emitting stage.

[0039] Figure 9 This is another schematic diagram of the pixel driving circuit in the present invention.

[0040] Figure 10 For the present invention Figure 9 This is the driving timing state diagram of the pixel driving circuit in the present invention.

[0041] Figure 11 For the present invention Figure 9 This is the schematic diagram of the pixel driving circuit of the present invention in the initialization stage.

[0042] Figure 12 For the present invention Figure 9 This is the schematic diagram of the pixel driving circuit of the present invention in the threshold compensation stage.

[0043] Figure 13 For the present invention Figure 9 This is the schematic diagram of the pixel driving circuit of the present invention in the data storage stage.

[0044] Figure 14 For the present invention Figure 9 This is the schematic diagram of the pixel driving circuit of the present invention in the light emitting stage.

[0045] Figure 15 This is the schematic diagram of the structure of the display panel.

[0046] Description of reference numerals:

[0047] 10 Pixel light emitting unit; 11 First power supply; 12 Second power supply; 20 Driving unit; 30 Data writing unit; 40 Data storage unit; 50 Threshold storage unit; 60 Control unit; T r Driving transistor; T D Switching transistor; T1 First transistor; T2 Second transistor; T3 Third transistor; T4 Fourth transistor; T5 Fifth transistor; Q Light emitting diode; C Capacitor; C1 First capacitor; C2 Second capacitor; Vss Reference voltage; V DD Power supply voltage; V scan Scanning control signal; V data Data voltage; K1 First control signal; K2 Second control signal; K3 Third control signal; K4 Fourth control signal; K5 Fifth control signal; A Potential point at the control end of the driving transistor. Detailed implementation manners

[0048] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0050] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0051] It should be noted that the transistors adopted in the embodiments of the present invention can be thin-film transistors, field-effect transistors or other devices with the same characteristics. Since the source and drain of a transistor can be interchanged under certain conditions, there is no difference in the description of their connection relationship between the source and drain. In the embodiments of the present invention, to distinguish the connection relationship of the transistor, one of the poles is called the first end, the other pole is called the second end, and the gate is called the control end. In addition, according to the characteristics of the transistor, the transistor can be divided into N-type and P-type. In this application, when a P-type transistor is adopted, at the initial stage, the drain of the P-type transistor is defined as the first end, the source of the P-type transistor is defined as the second end, and when the gate inputs a low level, the source and drain are turned on. The N-type is the opposite. When an N-type transistor is adopted, at the initial stage, the source of the N-type transistor is defined as the first end, the drain of the N-type transistor is defined as the second end, and when the gate inputs a high level, the source and drain are turned on. And during the working process, because the voltage across the transistor changes, the source and drain can be interchanged.

[0052] Please refer to Figure 1 As shown, a pixel driving circuit is provided on the display panel for driving each sub-pixel to emit light. The pixel driving circuit includes a light-emitting device Q, a driving transistor T r , a switching transistor T D and a capacitor C. Among them, the capacitor C stores the threshold voltage of the driving transistor T r . One end of the capacitor C is connected to the operating voltage V DD and the second end of the driving transistor T r , and the other end is connected to the first end of the switching transistor T D and the control end of the driving transistor T r . The control end of the switching transistor T D is connected to the scan control signal V scan , and the second end is connected to the data voltage Vdata , the first terminal is connected to the control terminal of driving transistor T r . The on / off state of switching transistor T D is controlled by a scan control signal V scan , thereby controlling the input of data voltage V data . The second terminal of driving transistor T r is connected to an operating voltage V DD , the first terminal is connected to the anode of light-emitting device Q, and the cathode of light-emitting device Q is connected to a reference voltage V SS . The data voltage V data is supplied to the control terminal of driving transistor T D through switching transistor T r to control the on / off state and current magnitude of driving transistor T r so as to control the light emission and light intensity of light-emitting device Q. When light-emitting device Q emits light, the current I Q flowing through light-emitting device Q r is the current corresponding to the gate-source voltage V gs of driving transistor T L , and the current I Q can be expressed by the following formula: I gs =k(V th -V 2 ) DD =k(V data -V th -|V 2 |) L . It can be seen from the formula that in the above pixel driving circuit, the current I r depends on the threshold voltage V th of driving transistor T

[0053] . Therefore, the change in the threshold voltage in the driving transistor will cause uneven light emission of light-emitting device Q, thereby affecting the display quality of the display panel.

[0054] Please refer to Figure 2 , Figure 3 and Figure 9As shown, the pixel driving circuit provided by the present invention includes a pixel light-emitting unit 10, a driving unit 20, a data writing unit 30, a data storage unit 40, a threshold storage unit 50, and a control unit 60. In the threshold compensation stage, the threshold storage unit 50 stores a voltage. A control instruction is written through the data writing unit 30 and stored in the data storage unit 40. When entering the light-emitting stage, the control instruction controls the control terminal of the driving unit 20, causing the driving unit 20 to operate, and causing the light-emitting device Q in the pixel unit to emit light. In the light-emitting stage, the voltage output by the threshold storage unit 50 cancels out the threshold voltage of the driving transistor Tr, which can avoid uneven light emission of the light-emitting device Q caused by the threshold voltage. The control unit 60 includes a plurality of transistors to adjust the connection relationship of each unit in different working stages of the pixel driving circuit. In this embodiment, the control unit 60 includes, for example, 5 transistors, such as a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, and a fifth transistor T5. A control signal is connected to the control terminal of each transistor to adjust the switching of each transistor.

[0055] Please refer to Figure 2 , Figure 3 and Figure 9 As shown, in an embodiment of the present invention, when using the pixel driving circuit provided by the present invention to drive a pixel, it may include an initialization stage, a threshold compensation stage, a data storage stage, and a light-emitting stage. In the initialization stage, the control unit 60 responds to an initial control signal, the second end of the threshold storage unit 50 is electrically connected to the second end of the driving unit 20 and a first power supply 11, and the first end of the threshold storage unit 50 is electrically connected to the data writing unit 30. In the threshold compensation stage, the control unit 60 responds to a threshold storage control signal, the first end of the threshold storage unit 50 is electrically connected to the first end and the control terminal of the driving unit 20, the second end of the threshold storage unit 50 is electrically connected to the second end of the driving unit 20, and the voltage difference of the threshold storage unit 50 is equal to the threshold voltage of the driving unit 20. In the data storage stage, the control unit 60 responds to a data storage control signal, the first end of the data storage unit 40 is electrically connected to the control terminal of the driving unit 20 and the data writing unit 30, the second end of the data storage unit 40 is electrically connected to the second end of the driving unit 20, and the data storage unit 40 stores a data voltage. In the light-emitting stage, the control unit 60 responds to a light-emitting control signal, the first end of the threshold storage unit 50 is electrically connected to the second end of the data storage unit 40, the second end of the threshold storage unit 50 is electrically connected to the second end of the driving unit 20, the first end of the data storage unit 40 is electrically connected to the control terminal of the driving unit 20, and the first end of the driving unit 20 is electrically connected to the second end of the pixel light-emitting unit 10.

[0056] Specifically, please refer toFigure 3 and Figure 9 As shown, in an embodiment of the present invention, the pixel light-emitting unit 10 includes, for example, a light-emitting device Q. And the light-emitting device Q is, for example, a light-emitting diode or other light-emitting devices. The second end of the light-emitting device Q is electrically connected to the first end of the driving unit 20. In this embodiment, the driving unit 20 includes, for example, a driving transistor T r , that is, the electrical connection of the light-emitting diode is to the first end of the driving transistor T r . By controlling the control end of the driving transistor T r , the conduction and cut-off of the first end to the second end of the driving transistor T r are controlled. That is, through the control end, the magnitude of the current from the first end to the second end of the driving transistor T r can be controlled, and thus whether the light-emitting device Q emits light can be controlled. Among them, the second end of the light-emitting device Q is electrically connected to the first end of the driving transistor T r , the first end of the light-emitting device Q is connected to the first power supply 11, and the second end of the driving transistor T r is connected to the second power supply 12. When the driving transistor T r is a P-type transistor, the voltage of the first power supply 11 is less than the voltage of the second power supply 12. When the driving transistor T r is an N-type transistor, the voltage of the first power supply 11 is greater than the voltage of the second power supply 12, and the light-emitting diode is always arranged along the direction of the voltage drop.

[0057] Please refer to Figure 3 and Figure 9 As shown, in an embodiment of the present invention, a first transistor T1 is further provided between the light-emitting device Q and the first end of the driving unit 20. The first end of the first transistor T1 is electrically connected to the second end of the pixel light-emitting unit 10, and the second end of the first transistor T1 is electrically connected to the first end of the driving unit 20. By inputting a first control signal K1 to the control end of the first transistor T1, whether the pixel light-emitting unit 10 is lit is controlled. Furthermore, it is possible to prevent the pixel light-emitting unit 10 from being accidentally lit in other stages except the light-emitting stage.

[0058] Please refer to Figure 3 and Figure 9 As shown, in an embodiment of the present invention, the data writing unit 30 is electrically connected to the control end of the driving unit 20. In this embodiment, the data writing unit 30 includes, for example, a switching transistor T D . The first end of the data writing unit 30 is electrically connected to the control end of the driving unit 20, the second end of the data writing unit 30 is connected to the data voltage V data , the control end is connected to the scan control signal, and the on / off of the switching transistor T D is controlled by the scan control signal V scan , thereby controlling the data voltage V datainput. When the switching transistor T D is turned on, the control data voltage V data can be input.

[0059] Please refer to Figure 3 and Figure 9 As shown in FIGS. and, in an embodiment of the present invention, the data storage unit 40 is electrically connected to the control end and the second end of the driving unit 20, and the data storage unit 40 includes, for example, a first capacitor C1. For example, one end of the first capacitor C1 electrically connected to the control end of the driving unit 20 is defined as the first end, and one end of the first capacitor C1 electrically connected to the threshold storage unit 50 is defined as the second end. The data storage unit 40 can store data in the first capacitor C1 during the data storage stage and output the stored voltage during the light emitting stage. A second transistor T2 is further provided between the second end of the data storage unit 40 and the driving unit 20. The first end of the second transistor T2 is electrically connected to the second end of the data storage unit 40 and the first end of the threshold storage unit 50, and the second end of the second transistor T2 is electrically connected to the second end of the driving unit 20. A second control signal K2 is input to the control end of the second transistor T2 to control whether the data storage unit 40 is electrically connected to the second end of the driving unit 20, so as to prevent the data storage unit 40 from being connected to the pixel driving circuit during the initialization stage and the threshold compensation stage.

[0060] Please refer to Figure 3 and Figure 9 As shown in FIGS. and, in an embodiment of the present invention, the threshold storage unit 50 is electrically connected to the second end and the first end of the driving unit 20, and the threshold storage unit 50 includes, for example, a second capacitor C2. For example, one end of the second capacitor C2 electrically connected to the second end of the first capacitor C1 is defined as the first end, and the other end of the second capacitor C2 is defined as the second end. The threshold storage unit 50 can store voltage during the threshold compensation stage and output voltage during the light emitting stage, and the voltage output by the threshold storage unit 50 during the light emitting stage cancels the threshold voltage of the driving transistor T r of.

[0061] Please refer to Figure 3 and Figure 9As shown, in an embodiment of the present invention, a third transistor T3 is disposed between the second end of the threshold storage unit 50 and the second end of the driving unit 20. The first end of the third transistor T3 is electrically connected to the second end of the threshold storage unit 50, the second end of the third transistor T3 is electrically connected to the second end of the driving unit 20, and a third control signal K3 is input to the control end of the third transistor T3 to control whether the second end of the threshold storage unit 50 is electrically connected to the second end of the driving unit 20. A fourth transistor T4 and a fifth transistor T5 are disposed between the first end of the threshold storage unit 50 and the first end of the driving unit 20. The first end of the fourth transistor T4 is electrically connected to the first end of the threshold storage unit 50 and the second end of the data storage unit 40, and the second end of the fourth transistor T4 is electrically connected to the control end of the driving unit 20 and the data writing unit 30. A fourth control signal K4 is input to the control end of the fourth transistor T4 to control whether the threshold storage unit 50 is connected to the control end of the driving unit 20. The first end of the fifth transistor T5 is electrically connected to the control end of the driving unit 20 and the data writing unit 30, and the second end of the fifth transistor T5 is electrically connected to the first end of the driving unit 20. A fifth control signal K5 is input to the control end of the fifth transistor T5 to control whether the threshold storage unit 50 is connected to the first end of the driving unit 20. When the fourth transistor T4 and the fifth transistor T5 are turned off, the threshold storage unit 50 and the data storage unit 40 are connected in series, that is, the second capacitor C2 and the first capacitor C1 are connected in series. When the fourth transistor T4 is turned on and the fifth transistor T5 is turned off, the threshold storage unit 50 is connected to the control end of the driving unit 20. When the fourth transistor T4 and the fifth transistor T5 are turned on, the threshold storage unit 50 is connected to the first end and the second end of the driving unit 20. The cooperation of the third transistor T3, the fourth transistor T4 and the fifth transistor T5 can prevent the threshold storage unit 50 from being connected in the circuit during the data storage stage, prevent the data storage unit 40 from being short-circuited during the initialization stage and the threshold compensation stage, prevent incorrect data writing, and ensure that during the threshold compensation stage, both ends of the threshold storage unit 50 are connected to the first end and the second end of the driving unit 20 to ensure that the voltage value stored in the threshold storage unit 50 is equal to the threshold voltage of the driving unit 20.

[0062] Please refer to Figure 2 、 Figure 3 、 Figure 4 、 Figure 9 and Figure 10As shown, in the present application, any one of the transistors in the driving unit 20, the data writing unit 30, and the control unit 60 can be a P-type transistor or an N-type transistor. By adjusting the control signal at the control terminal, it is only necessary to ensure that each transistor conforms to the on and off functions at each stage of pixel driving. In the present application, for example, taking all transistors as P-type transistors and all transistors as N-type transistors as examples, the control method of the pixel driving circuit is described. During each lighting cycle of the pixel, the control method of the pixel unit provided by the present invention includes an initialization stage, a threshold compensation stage, a data storage stage, and a light emitting stage. It can be conceived that any one transistor, whether using an N-type transistor or a P-type transistor to implement the function of the pixel driving circuit in the present invention, can be easily conceived by those skilled in the art without creative labor, and thus is also within the protection scope of the embodiments of the present invention.

[0063] Please refer to Figures 3 to 8 As shown, in an embodiment of the present invention, when the transistors in the pixel driving circuit are P-type transistors, the timing of each control signal is as Figure 4 described, and the circuit state diagram of each stage is as Figures 5 to 8 shown.

[0064] Please refer to Figure 4 and Figure 5 As shown, in an embodiment of the present invention, the initialization stage is to charge the second capacitor C2 in the threshold storage unit 50, so that the driving transistor T r conducts in the threshold compensation stage, then it is necessary to satisfy that the driving transistor T r has |V gsr | > |V thr |, that is, V DD - V C2 > |V thr |, where V gsr is the gate-source voltage of the driving transistor T r , V thr is the threshold voltage of the driving transistor Tr, and V C2 is the voltage collected and stored on the second capacitor C2. In this embodiment, the second power supply 12 is set to the high potential V DD , and the first power supply 11 is set to the reference voltage V SS .

[0065] Specifically, please refer to Figure 4 and Figure 5As shown, during the initialization phase, in response to an initial control signal, specifically, for example, the third control signal K3 and the fourth control signal K4 are both set to a low potential, causing the third transistor T3 and the fourth transistor T4 to conduct. The first control signal K1, the second control signal K2, and the fifth control signal K5 are all set to a high potential, causing the first transistor T1, the second transistor T2, and the fifth transistor T5 to cut off. And in order to enable the switching transistor T D to conduct, the scan control signal V scan is set to a low potential, and it satisfies V data - V scan >|V thD | (where V thD is the threshold voltage of the switching transistor T D ). Additionally, in order to make the driving transistor T r satisfy |V gsr |>|V thr |, then it is necessary to set V DD -|V thr |>V data , so it is necessary to set V data to V DD -|V thr |>V data >|V thr |+V scan . During the initialization phase, since the first transistor T1 is cut off, the light-emitting diode Q is open-circuited and not lit. And because one end of the second capacitor C2 is connected to the power supply voltage V DD , the other end of the second capacitor C2 is connected to the data voltage V data , the power supply voltage V DD and the data voltage V data combine to charge the second capacitor C2, so that the voltage V C2 stored on the second capacitor C2 is V DD - V data .

[0066] Please refer to Figure 4 and Figure 6 shown. In an embodiment of the present invention, the threshold compensation phase is to adjust the voltage of the threshold storage unit 50 so that during the discharge phase, the voltage stored in the threshold storage unit 50 can cancel out the threshold voltage of the driving unit 20. Specifically, in response to the threshold storage control signal, the control unit, for example, based on the initialization phase shown in Figure 5 , sets the scan control signal V scan to a high potential, causing the switching transistor T DTurn into cutoff. Set the fifth control signal K5 to a low potential to turn on the fifth transistor T5. At the start of the threshold compensation phase, the potential at point A (point A is the potential point at the control terminal of the driving transistor) is V A = V DD - V C2 = V DD - ( VDD - V data ) = V data , |V gsr | = V DD - V A = V DD - V data >|V thr |, and the driving transistor Tr turns on. As time goes by, the potential at point A rises rapidly, and at the same time, the second capacitor C2 discharges through the source and drain of the driving transistor T r until the driving transistor T r just cuts off, that is, the voltage |V r | across the gate-source of the driving transistor T gsr is just equal to the threshold voltage |V thr |. At this time, V C2 = |V thr |, which is equivalent to storing the threshold voltage V r of the driving transistor T thr onto the second capacitor C2. During the threshold compensation phase, the first control signal K1 is set to a high potential, the first transistor T1 cuts off, and the light-emitting diode Q is open-circuited and not lit.

[0067] Please refer to Figure 4 and Figure 7 as shown. In an embodiment of the present invention, during the data storage phase, the data signal is stored in the data storage unit 40 and displayed during the light-emitting phase. Specifically, the control unit responds to the data storage control signal. For example, based on the threshold compensation phase shown in Figure 6 , the third control signal K3, the fourth control signal K4, and the fifth control signal K5 are set to high potentials to turn off the third transistor T3, the fourth transistor T4, and the fifth transistor T5. The second control signal K2 and the scan control signal V scan are set to low potentials to turn on the second transistor T2 and the switching transistor T D . At this time, the potential at point A becomes V data , and at the same time, the power supply voltage V DD and the data voltage V data are combined to charge the first capacitor C1, so that the potential at point A remains V data , which is equivalent to storing the data voltage V data in the first capacitor C1, and V C1 = VDD -V data During the data storage phase, the first control signal K1 is set to a high potential, the first transistor T1 is turned off, and the light-emitting diode Q is open-circuited and not lit.

[0068] Please refer to Figure 4 and Figure 8 As shown, in an embodiment of the present invention, during the light-emitting phase, the light-emitting diode in the pixel light-emitting unit 10 is lit according to an instruction. Specifically, the control unit responds to the light-emitting control signal. For example, based on the data storage phase shown in Figure 7 , the first control signal K1 and the third control signal K3 are set to a low potential, so that the first transistor T1 and the third transistor T3 become conductive, and the second control signal K2 and the scan control signal V scan are set to a high potential, so that the second transistor T2 and the switch transistor T D become non-conductive. At this time, the potential at point A is V A = V DD -V C2 -V C1 = VDD - |V thr | - (V DD -V data ) = V data -|V thr |. For the driving transistor Tr, |V gsr | = V DD -V A = V DD -V data +|V thr | > 2|V thr |, the driving transistor T r is conductive. According to the current formula of the MOS transistor I Q = k(V gs -V th ) 2 , since the driving transistor T r is a PMOS transistor, V thr = -|V thr |, I Q = k(V gs -V th ) 2 = k(V gsr +|V thr |) 2 = k(V A -V DD +|V thr |) 2 = k(V data -|V thr |-V DD +|Vthr |) 2 = k(V data - V DD ) 2 . Therefore, the light-emitting diode Q emits light under the drive of the drive current I Q = k(V data - V DD ) 2 , that is, in the light-emitting stage, the threshold voltage V r of the drive transistor T thr is eliminated from the drive current I Q .

[0069] Please refer to Figures 9 to 14 As shown, in another embodiment of the present invention, when the transistors in the pixel drive circuit are all N-type transistors, the timing of each control signal is as Figure 10 described, and the circuit state diagram of each stage is as Figures 11 to 14 shown. In this embodiment, the first power supply 11 is set to the power supply voltage V DD , and the second power supply 12 is set to the reference voltage V SS .

[0070] Please refer to Figure 10 and Figure 11 shown. In another embodiment of the present invention, in the initialization stage, the control unit responds to the initial control signal. Specifically, for example, it includes setting the scan control signal V scan , the second control signal K2, and the fourth control signal K4 to high potential, so that the switching transistor TD, the second transistor T2, and the fourth transistor T4 are turned on. The first control signal K1, the third control signal K3, and the fifth control signal K5 are all set to low potential, so that the third transistor T3, the first transistor T1, and the fifth transistor T5 are turned off. And in order to enable the switching transistor T D to be turned on, the scan control signal V scan is set to high potential. In addition, in order to make the drive transistor Tr satisfy |V gsr | > |V thr |, that is, V data - V SS = V C2 > |V thr |, then V data needs to be set to high potential. Among them, V gsr is the gate-source voltage of the drive transistor Tr, V thr is the threshold voltage of the drive transistor T r , and V C2 is the voltage stored on the second capacitor C2. In the initialization stage, the first control signal K1 is set to low potential, the first transistor T1 is turned off, and the light-emitting diode Q is open-circuited and not lit.

[0071] For more details, please refer to Figure 10 and Figure 11 As shown, the initialization is to charge the second capacitor C2 in the threshold storage unit 50, so that the driving transistor T r conducts during the threshold voltage acquisition phase. During the initialization phase, one end of the second capacitor C2 is connected to the reference voltage V SS , and the other end of the second capacitor C2 is connected to the data voltage V data . The combination of the reference voltage V SS and the data voltage V data charges the second capacitor C2, so that the voltage V C2 stored on the second capacitor C2 is V data -V SS .

[0072] Please refer to Figure 10 and Figure 12 As shown, in another embodiment of the present invention, during the threshold compensation phase, the control unit responds to the threshold storage control signal. For example, based on the initialization phase shown in Figure 11 , the scan control signal V scan is set to a low potential, so that the switching transistor T D becomes cut off, and the fifth control signal K5 is set to a high potential, so that the fifth transistor T5 becomes conductive. At the beginning, the potential at point A is V A =V C2 +Vss=(V data -V SS )+V SS =V data , |V gsr |=V A -V SS =V C2 >|V thr |, and the driving transistor T r conducts. As time goes by, the potential at point A rises rapidly, and at the same time, the second capacitor C2 discharges through the source and drain of the driving transistor T r , until the driving transistor T r just cuts off, that is, the voltage |V r | between the gate and source of the driving transistor T gsr is just equal to the threshold voltage |V thr |. At this time, V C2 =|V thr |, which is equivalent to storing the threshold voltage V r of the driving transistor T thr on the second capacitor C2. During the threshold compensation phase, the first control signal K1 is set to a low potential, the first transistor T1 is cut off, and the light-emitting diode Q is open-circuited and not lit.

[0073] Please refer to Figure 10 and Figure 13 As shown, in another embodiment of the present invention, during the data storage stage, the control unit responds to the data storage control signal. For example, based on the threshold compensation stage shown in Figure 12 , the second control signal K2, the fourth control signal K4, and the fifth control signal K5 are set to low potential, causing the second transistor T2, the fourth transistor T4, and the fifth transistor T5 to become cutoff. The third control signal K3 and the scan control signal V scan are set to high potential, causing the third transistor T3 and the switching transistor T D to become conductive. At this time, the potential at point A becomes V data , and at the same time, the reference voltage V SS and the data voltage V data are combined to charge the first capacitor C1, causing the potential at point A to remain V data , which is equivalent to storing the data voltage V data in the first capacitor C1. V C1 =V data -V SS . During the data storage stage, the first control signal K1 is set to low potential, the first transistor T1 is cutoff, and the light-emitting diode Q is open-circuited and not lit.

[0074] Please refer to Figure 10 and Figure 14 As shown, in another embodiment of the present invention, during the light-emitting stage, the control unit responds to the light-emitting control signal. For example, based on the data storage stage shown in Figure 13 , the first control signal K1 and the second control signal K2 are set to high potential, causing the first transistor T1 and the second transistor T2 to become conductive. The third control signal K3 and the scan control signal V scan are set to low potential, causing the third transistor T3 and the switching transistor T D to become cutoff. At this time, the potential at point A is V A =V SS +V C2 +V C1 =V SS +|V thr |+(V data -V SS )=V data +|V thr . For the driving transistor T r , |V gsr |=V A -V SS =V data +|V thr |-V SS, the driving transistor T r conducts. According to the current formula of the MOS transistor I Q = k(V gs - V th ) 2 , since the driving transistor T r is an NPMOS transistor, V thr = |V thr |, I Q = k(V gs - V th ) 2 = k(V gsr - |V thr |) 2 = k(V data + |V thr |- V SS - |V thr |) 2 = k(V data - V SS ) 2 , therefore, the light-emitting diode Q emits light under the drive of the drive current I Q = k(V data - V SS ) 2 , that is, in the light-emitting stage, the threshold voltage V thr of the driving transistor Tr has no influence on the drive current I Q .

[0075] Please refer to Figure 15 shown. A display panel with stable brightness provided by the present invention. In different embodiments, the display panel described in the present invention can be, for example, an OLED display panel and / or a light-emitting diode display panel or other display panels. In some embodiments, the display panel can also be a mini-LED display panel or a micro-LED display panel, etc.

[0076] Please refer to Figure 15 shown. In an embodiment of the present invention, the display panel includes a plurality of pixel light-emitting units 10 and pixel driving circuits. The light-emitting devices in the pixel light-emitting units 10 are, for example, light-emitting diodes. The plurality of light-emitting diodes are arranged in an array, and each light-emitting diode forms a sub-pixel ( Figure 15 the R, G, B in can ), emitting red, green or blue light, and the plurality of light-emitting diodes are correspondingly connected to the plurality of pixel driving circuits. On the display panel, a scan driving signal generation circuit, a light-emitting control signal generation circuit, and a data driving signal generation circuit are also provided. The scan driving signal generation circuit generates a scan control signal S can, the light emission control signal generation circuit generates a first control signal K1, a second control signal K2, a third control signal K3, a fourth control signal K4, and a fifth control signal K5, and the data driving signal generation circuit generates a data voltage V data . Among them, the scan driving signal generation circuit includes a plurality of scan signal lines, and each scan signal line provides a scan control signal Vscan for one or more sub-pixels in the display area. The light emission control signal generation circuit includes a plurality of control signal lines, and each control signal line provides a first control signal K1, a second control signal K2, a third control signal K3, a fourth control signal K4, and a fifth control signal K5 for one or more sub-pixels in the display area. The data driving signal generation circuit includes a plurality of data driving signal lines, and each data driving signal line provides a data voltage V data .

[0077] Please refer to Figure 15 As shown, the present invention also provides an electronic device. The electronic device can be applied to, for example, but not limited to, electronic devices such as mobile phones, tablets, displays, MP3 players, MP4 players, smart watches, smart helmets, or other wearable devices. And the electronic device at least includes the display panel provided by the present invention, as well as a driving device, a power supply device, and a housing. The display panel is mounted on the housing, the driving device and the power supply device are arranged inside the housing, and the power supply device is electrically connected to the driving device, and the driving device is electrically connected to the display panel. The housing provided in this embodiment can form a chamber, the driving device and the power supply device can be placed in the chamber, and a plurality of buttons can be provided on the housing to input operation instructions. The power supply device can be, for example, a power board that converts commercial power into a specific voltage, or a battery. The power supply device is used to supply power to the driving device and the display panel. The driving device is, for example, a control board that can adjust the state of the display panel according to instructions.

[0078] In summary, a pixel driving circuit and its application provided by the present invention store a voltage in a threshold storage unit before lighting a pixel light-emitting unit, and the stored voltage value is equal to the threshold voltage of the driving unit. When the pixel light-emitting unit is lit, the voltage in the threshold storage unit cancels out the threshold voltage of the driving unit, effectively realizing the threshold voltage compensation of the driving unit, making the driving current of the pixel light-emitting unit independent of the threshold voltage of the corresponding driving unit, effectively avoiding the influence of various factors such as inherent process structure differences or environmental temperature fluctuations on the threshold voltage of the driving transistor on the driving current, and improving the display quality. When applied to a display panel and an electronic device subsequently, since the threshold voltages of the driving transistors of the pixel light-emitting units in the display panel are all compensated, the light-emitting differences of the pixel light-emitting units at different positions can be greatly reduced, thereby improving the gray-scale and brightness control accuracy of the display panel, and further improving the display effect of the display panel.

[0079] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A pixel driving circuit, comprising a pixel light-emitting unit, a driving unit, a data writing unit, and a data storage unit, characterized in that It further includes a threshold storage unit and a control unit: The control unit responds to a threshold storage control signal and is configured to electrically connect a first end of the threshold storage unit to a first end and a control end of the driving unit, electrically connect a second end of the threshold storage unit to a second end of the driving unit, and make a voltage difference of the threshold storage unit equal to a threshold voltage of the driving unit; The control unit responds to a data storage control signal and is configured to electrically connect a first end of the data storage unit to a control end of the driving unit and the data writing unit, electrically connect a second end of the data storage unit to a second end of the driving unit, and make the data storage unit store a data voltage; And The control unit responds to a light emission control signal and is configured to electrically connect a first end of the threshold storage unit to a second end of the data storage unit, electrically connect a second end of the threshold storage unit to a second end of the driving unit, electrically connect a first end of the data storage unit to a control end of the driving unit, and electrically connect a first end of the driving unit to the pixel light emitting unit.

2. The pixel driving circuit according to claim 1, wherein The control unit further responds to an initial control signal and is configured to electrically connect a second end of the threshold storage unit to a second end of the driving unit and a second power supply, and electrically connect a first end of the threshold storage unit to the data writing unit.

3. The pixel driving circuit according to claim 2, wherein The control unit includes a first transistor, a second transistor, a third transistor, a fourth transistor and a fifth transistor; A first end of the first transistor is electrically connected to a second end of the pixel light emitting unit, and a second end of the first transistor is electrically connected to a first end of the driving unit; A first end of the second transistor is electrically connected to a second end of the data storage unit and a first end of the threshold storage unit, and a second end of the second transistor is electrically connected to a first end of the driving unit; A first end of the third transistor is electrically connected to a second end of the threshold storage unit, and a second end of the third transistor is electrically connected to a second end of the driving unit; A first end of the fourth transistor is electrically connected to a first end of the threshold storage unit and a second end of the data storage unit, and a second end of the fourth transistor is electrically connected to a control end of the driving unit and the data writing unit; A first end of the fifth transistor is electrically connected to a control end of the driving unit and the data writing unit, and a second end of the fifth transistor is electrically connected to a first end of the driving unit.

4. The pixel driving circuit according to claim 3, wherein The control unit responds to the initial control signal, disconnects a first end and a second end of the first transistor, disconnects a first end and a second end of the second transistor, connects a first end and a second end of the third transistor, connects a first end and a second end of the fourth transistor, and disconnects a first end and a second end of the fifth transistor.

5. The pixel driving circuit according to claim 3, characterized in that, In response to the threshold storage control signal, the control unit disconnects the first end and the second end of the first transistor, disconnects the first end and the second end of the second transistor, connects the first end and the second end of the third transistor, connects the first end and the second end of the fourth transistor, and connects the first end and the second end of the fifth transistor.

6. The pixel driving circuit according to claim 3, wherein In response to the data storage control signal, the control unit disconnects the first end and the second end of the first transistor, connects the first end and the second end of the second transistor, disconnects the first end and the second end of the third transistor, disconnects the first end and the second end of the fourth transistor, and disconnects the first end and the second end of the fifth transistor.

7. The pixel driving circuit according to claim 3, wherein In response to the light emission control signal, the control unit connects the first end and the second end of the first transistor, disconnects the first end and the second end of the second transistor, connects the first end and the second end of the third transistor, disconnects the first end and the second end of the fourth transistor, and disconnects the first end and the second end of the fifth transistor.

8. The pixel driving circuit according to claim 1, wherein The second end of the driving unit is electrically connected to a second power supply, the control end of the driving unit is electrically connected to the first end of the data writing unit, and the first end of the pixel light emitting unit is electrically connected to a first power supply.

9. A display panel, characterized in that, Comprising the pixel driving circuit according to claim 1.

10. An electronic device, characterized in that, Comprising the display panel according to claim 9.

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