Pixel driving circuit and display device

Abstract

The present application relates to the technical field of terminal devices, and provides a pixel driving circuit and a display device, for use in driving light-emitting devices to emit light. The circuit comprises: a switch sub-circuit comprising a driving switch, wherein the driving switch is separately connected to a first node and a first system voltage end and electrically connected to a light-emitting device, and the driving switch is used for enabling a path between the first system voltage end and the light-emitting device; an initialization sub-circuit electrically connected to an initialization signal end and the first node, separately, and used for initializing the voltage of the first node by means of a signal inputted by the initialization signal end; and a write sub-circuit connected to the first node and a data signal end, separately, and used for enabling a path between the data signal end and the first node. By means of the solution in the present application, the initialization sub-circuit can be used to control the driving switch, thereby improving the efficiency of pixel driving, and at the same time, the signal sent by the data signal end is written into a control end of the driving switch, such that the driving switch generates a corresponding driving current to drive the light-emitting device to emit light.

Description

Pixel driving circuit and display device

[0001] The present application claims priority to the Chinese patent application No. 202410875173.1, filed on July 1, 2024, and entitled "A pixel driving circuit and display device", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of terminal equipment, and in particular to a pixel driving circuit and display device. BACKGROUND

[0003] The display screen is an important component in the display device, and its display effect has an important influence on the use of the display device.

[0004] In the display screen technology based on LTPS (Low Temperature Poly-Silicon) pixel driving, due to the non-uniformity of LTPS at low gray scale, higher frequency pulses and longer off time are required to act on the driving circuit to drive the pixels, so that the display screen appears uniform, and LTPS has poor hysteresis, which causes serious residual image of the display screen, affecting the driving efficiency of the pixels in the display screen and the display effect. SUMMARY

[0005] The present application provides a pixel driving circuit and display device to solve the problem of low pixel driving efficiency affecting the display effect in the display screen.

[0006] In a first aspect, the present application provides a pixel driving circuit for driving a light emitting device to emit light, the circuit comprising a switching sub-circuit, an initialization sub-circuit and a writing sub-circuit; wherein the switching sub-circuit comprises a driving switch, the control end of the driving switch is electrically connected with a first node, the first end of the driving switch is connected with a first system voltage end, the second end of the driving switch is connected with the input end of the light emitting device, and the driving switch is configured to conduct the line between the first system voltage end and the input end of the light emitting device in response to the voltage of the first node; the input end of the initialization sub-circuit is electrically connected with an initialization signal end, the output end of the initialization sub-circuit is electrically connected with the first node, and the initialization sub-circuit is configured to initialize the voltage of the first node by using the signal input from the initialization signal end in response to an initialization control signal; the output end of the writing sub-circuit is connected with the first node, and the input end of the writing sub-circuit is electrically connected with a data signal end, and the writing sub-circuit is configured to conduct the line between the data signal end and the first node in response to a writing control signal.

[0007] In this way, by electrically connecting the initialization sub-circuit and the write sub-circuit with the control end of the driving switch, the initialization sub-circuit is used to control the driving switch, the efficiency of pixel driving is improved, and the signal sent by the data signal end is written to the control end, so that the driving switch generates a corresponding driving current to drive the light emitting device to emit light.

[0008] In an implementation, the write sub-circuit includes a write switch, a control end of the write switch is electrically connected with the write control end, an input end of the write switch is electrically connected with the data signal end, and an output end of the write switch is connected with the first node. The write switch is configured to turn on a circuit between the data signal end and the first node in response to a write control signal input by the write control end. In this way, the write switch is used to control the turn-on relationship between the data signal end and the first node, so that the data signal can be coupled to the first node in the write stage, and the driving switch is controlled.

[0009] In an implementation, the initialization sub-circuit includes a first initialization switch, a first end of the first initialization switch is electrically connected with the third node, a second end of the first initialization switch is electrically connected with the first initialization signal end, and a control end of the first initialization switch is electrically connected with the first control signal end. The third node is arranged between the second end of the driving switch and the input end of the light emitting device, and the third node is connected with the first node. The first initialization switch is configured to turn on a circuit between the first initialization signal end and the first node in response to a first initialization control signal input by the first control signal end. In this way, the third node is stabilized, and the input voltage of the light emitting device is stabilized to avoid the brightness of the light emitting device from being affected by other voltage values.

[0010] In an implementation, the circuit further includes a first compensation switch, a first end of the first compensation switch is electrically connected with the first node, and a second end of the first compensation switch is electrically connected with the second node. The second node is arranged between the first end of the driving switch and the first system voltage end. The first compensation switch is configured to turn on the first node and the second node in response to a compensation control signal to compensate for the threshold voltage of the driving switch. In this way, the threshold voltage of the driving switch is compensated by the first compensation switch, so that the voltage of the first node records the threshold voltage of the driving switch, and the response uniformity of the driving switch is improved.

[0011] In an implementation, a first end of the driving switch is electrically connected to the second node, a second end of the driving switch is electrically connected to the third node, and a control end of the driving switch is electrically connected to the first node; the switch sub-circuit is further configured to, in response to the first initialization switch and the first compensation switch being turned on at the same time, transmit a first initialization signal input by the first initialization signal terminal to the first node through the driving switch, so as to compensate for a threshold voltage of the driving switch. In this way, the first initialization signal terminal can be used to complete the compensation process of the threshold voltage of the driving switch, and the response efficiency of the driving switch is improved.

[0012] In an implementation, the initialization sub-circuit further includes a second initialization switch and a third initialization switch; a first end of the second initialization switch is electrically connected to the first node, a second end of the second initialization switch is electrically connected to a second initialization signal terminal, and a control end of the second initialization switch is electrically connected to a second control signal terminal; the second initialization switch is configured to, in response to a second initialization control signal input by the second control signal terminal, turn on a line between the second initialization signal terminal and the first node; a first end of the third initialization switch is connected to an output terminal of the write sub-circuit to form a fourth node, a second end of the third initialization switch is electrically connected to a third initialization signal terminal, and a control end of the third initialization switch is electrically connected to a third control signal terminal; the third initialization switch is configured to, in response to a third initialization control signal input by the third control signal terminal, turn on a line between the third initialization signal terminal and the fourth node. In this way, the data signal can be coupled, so that the compensation effect on the first node in the compensation stage is better, and the driving efficiency is improved.

[0013] In an implementation, the circuit further includes a storage sub-circuit arranged between the first node and the third node, and the storage sub-circuit is configured to stabilize voltages of the first node, the third node, and the fourth node after the initialization sub-circuit performs initialization. In this way, the nodes can be stabilized after the initialization stage, so that the light-emitting device can maintain a light-emitting state.

[0014] In an implementation, the storage sub-circuit includes a first capacitor and a second capacitor, the first capacitor is arranged between the first node and the fourth node, and the second capacitor is arranged between the third node and the fourth node. In this way, the data signal can be coupled and divided, so as to control the driving switch and improve the driving efficiency.

[0015] In an implementation, a difference between a voltage of a signal input by the second initialization signal terminal and a voltage of a signal input by the first initialization signal terminal is greater than a threshold voltage of the driving switch. In this way, the initialization sub-circuit can compensate for the first node and complete the initialization process, the structural complexity is reduced, and accurate control of the pixel driving circuit is achieved.

[0016] In an implementation, the circuit further comprises a second compensation switch, an output terminal of the second compensation switch is electrically connected with the fifth node, an input terminal of the second compensation switch is electrically connected with the compensation signal terminal, and the fifth node is arranged between the second terminal of the driving switch and the third node; the second compensation switch is configured to, in response to the compensation control signal, turn on a line between the compensation signal terminal and the fifth node; the first terminal of the driving switch is electrically connected with the second node, the second terminal of the driving switch is electrically connected with the fifth node, and the control terminal of the driving switch is electrically connected with the first node; the switch sub-circuit is further configured to, in response to the first compensation switch and the second compensation switch being turned on at the same time, transmit the compensation signal input by the compensation signal terminal to the first node through the driving switch, so as to compensate the threshold voltage of the driving switch. In this way, the compensation signal terminal can be used to compensate the threshold voltage, so that the first initialization signal can be set to a negative value, so as to optimize the compensation effect of the driving switch.

[0017] In an implementation, the switch sub-circuit further comprises a first light-emitting control switch, the first light-emitting control switch is arranged between the first terminal of the driving switch and the first system voltage terminal, and the first light-emitting control switch is configured to, in response to the light-emitting control signal, turn on a line between the first system voltage terminal and the first terminal of the driving switch. In this way, the line between the first system voltage terminal and the light-emitting device can be controlled, so as to avoid the problem of the light-emitting device being turned on by mistake.

[0018] In an implementation, the first terminal of the driving switch is electrically connected with the first light-emitting control switch, the second terminal of the driving switch is electrically connected with the third node, and the control terminal of the driving switch is electrically connected with the first node; the switch sub-circuit is further configured to, in response to the first light-emitting control switch and at least one of the second initialization switch and the third initialization switch being turned on at the same time, transmit the system voltage input by the first system voltage terminal to the third node through the driving switch; and the initialization sub-circuit is further configured to, in response to the first light-emitting control switch and at least one of the second initialization switch and the third initialization switch being turned on at the same time, transmit the initialization signal input by the second initialization signal terminal and / or the third initialization signal terminal to the first node, so as to compensate the threshold voltage of the driving switch. In this way, the threshold voltage of the driving switch can be compensated by using at least one of the first system voltage terminal, the second initialization signal terminal and the third initialization signal terminal, so that the threshold voltage compensation can be realized by the initialization sub-circuit and the switch sub-circuit without additionally arranging a switch for compensation, and the driving efficiency of the pixel driving circuit is improved.

[0019] In an implementation, the switch sub-circuit further comprises a second light-emitting control switch, which is arranged between the second end of the driving switch and the input end of the light-emitting device, and is configured to turn on the line between the second end of the driving switch and the input end of the light-emitting device in response to a light-emitting control signal. In this way, the input compensation signal can be prevented from affecting the light-emitting effect of the light-emitting device during the compensation process, and the light-emitting stability of the light-emitting device is improved.

[0020] In an implementation, the first light-emitting control switch and the second light-emitting control switch are both transistors; the transistors are P-type transistors; or the transistors are N-type transistors. In this way, the transistors can be used to receive the voltage signal and control the pixel driving switch.

[0021] In a second aspect, the present application also provides a display panel, comprising a plurality of pixel driving circuits according to any of the foregoing implementations, and a light-emitting device connected to each pixel driving circuit.

[0022] In a third aspect, the present application also provides a display device, comprising: a housing; and a display panel according to any of the foregoing implementations, which is mounted on the housing.

[0023] It can be understood that the beneficial effects achieved by the technical solutions of the second aspect to the third aspect provided above can refer to the beneficial effects of the first aspect and any of the optional implementations thereof, which will not be described here again. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the present application, the drawings required in the embodiments will be briefly introduced below. Obviously, other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0025] FIG. 1 is a structural schematic diagram of an OLED display screen;

[0026] FIG. 2 is a structural schematic diagram of a first pixel driving circuit according to an embodiment of the present application;

[0027] FIG. 3 is a structural schematic diagram of a second pixel driving circuit according to an embodiment of the present application;

[0028] FIG. 4 is a driving timing schematic diagram of the circuit in FIG. 3 according to an embodiment of the present application;

[0029] FIG. 5 is a structural schematic diagram of a third pixel driving circuit according to an embodiment of the present application;

[0030] FIG. 6 is a first driving timing schematic diagram of the circuit in FIG. 5 according to an embodiment of the present application;

[0031] Fig. 7 is a second driving timing diagram of the circuit in Fig. 5 according to an embodiment of the present application;

[0032] Fig. 8 is a third and fourth driving timing diagram of the circuit in Fig. 5 according to an embodiment of the present application;

[0033] Fig. 9 is a structure diagram of a fourth pixel driving circuit according to an embodiment of the present application;

[0034] Fig. 10 is a first to fourth driving timing diagram of the circuit in Fig. 9 according to an embodiment of the present application;

[0035] Fig. 11 is a diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0036] The technical solutions of the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application.

[0037] In the description of the present application, unless otherwise specified, " / " means "or", for example, A / B can mean A or B. "And / or" in the present application is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, "at least one" means one or more, and "multiple" means two or more. "First", "second", etc. do not limit the quantity and execution order, and "first", "second", etc. do not necessarily mean different.

[0038] It should also be understood that in the present application, unless otherwise specified and limited, the term "connection" can be electrical connection, communication connection or physical connection; at the same time, "connection" can be direct connection or indirect connection through intermediate medium.

[0039] It should be noted that in the present application, "exemplary" or "for example" is used to represent an example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the use of "exemplary" or "for example" is intended to present the relevant concept in a specific manner.

[0040] In order to make the following embodiments clear and simple, first give a brief introduction of related art:

[0041] OLED, Organic Light-Emitting Diode, i.e. organic light emitting diode. OLED display screen is a display screen using organic light emitting diode technology, which belongs to self-luminous display technology.

[0042] Gray Scale, a way to express the brightness change of an image, uses different gray levels to represent the brightness of different regions in the image. For example, in the gray scale, the change of brightness from black to white contains a total of 256 gray levels, that is, the gray scale range is 0 to 255. Among them, smaller gray values represent darker regions, and larger gray values represent brighter regions. Using gray scale can effectively represent black and white images, and can also be used to convert color images to black and white images.

[0043] TFT, Thin Film Transistor, thin film field effect transistor.

[0044] PMOS, positive channel Metal Oxide Semiconductor, P-type metal oxide semiconductor.

[0045] NMOS, N-Metal-Oxide-Semiconductor, N-type metal oxide semiconductor.

[0046] LTPS, Low Temperature Poly-silicon, low temperature polysilicon.

[0047] IGZO, indium gallium zinc oxide, indium gallium zinc oxide.

[0048] The application scenarios of the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0049] FIG. 1 is a structural schematic diagram of an OLED display screen.

[0050] As shown in FIG. 1, the OLED display screen can include a pixel array in the middle, a pixel driving circuit below the pixel array, a peripheral driving circuit in the same layer as the pixel driving circuit, and a support back plate below the peripheral driving circuit and an encapsulation layer on top.

[0051] Among them, the pixel array is the effective display area of the OLED display screen, which is used to display content. For example, a typical distribution of the pixel array is an array of 1920x1080 pixels. Each pixel in the pixel array includes a red green blue light emitting diode (RGB LED).

[0052] Specifically, the OLED display screen is driven by the DDIC (Display Driver IC, display driving chip) to drive the pixel driving circuit and the peripheral driving circuit to use the RGB OLED for color mixing, and convert the image display content into an optical signal of the display screen.

[0053] According to the light emitting characteristics of the OLED material, when the OLED display screen displays a dark picture, i.e. in a low gray scale, the display is not uniform due to the low luminance of the pixels.

[0054] In the OLED display screen based on LTPS, in order to make the image display in a low gray scale more uniform, a high frequency PWM (Pulse Width Modulation) is usually used to drive the driving circuit. Specifically, the same voltage is used to act on the driving circuit when displaying in high brightness, so that the TFT in the driving circuit works in a high current region. However, using a higher frequency and a longer off time to act on the driving circuit will increase the energy consumption of the display screen and affect the response efficiency of the display screen. Further, since the hysteresis of LTPS is poor, changing the driving current of the OLED pixel will affect the luminance and color of the pixel, which will cause abnormal phenomena such as color shift, image distortion, residual image, etc. of the OLED display screen. Especially in a low gray scale, since the luminance of the pixel is low, the interference of the magnetic field on the driving current of the pixel can be more significant, which will make the display effect of the OLED display screen more uneven.

[0055] Meanwhile, in some indoor environments, when using high frequency PWM for driving, multiple pulses are needed for driving. Compared with one pulse, the display screen has a greater impact on the eyes of the user, which is not conducive to the eye protection effect of the display screen.

[0056] To solve the above problems, the present application provides a pixel driving circuit to drive the OLED, so as to make the display effect of the OLED display screen more uniform, improve the driving efficiency of the display screen and improve the display effect of the display screen.

[0057] FIG. 2 is a structural schematic diagram of a first pixel driving circuit provided by an embodiment of the present application.

[0058] As shown in FIG. 2, the pixel driving circuit provided by the embodiment of the present application can include a switching sub-circuit 10, an initialization sub-circuit 20 and a writing sub-circuit 30. The switching sub-circuit 10 is used to control the light emission and brightness of a light emitting device 40 connected to the pixel driving circuit. In the embodiment of the present application, the light emitting device 40 can be an OLED.

[0059] For example, the switching sub-circuit 10 can include a driving switch 11, the control end of which is electrically connected to a first node N1, the first end of which is connected to a first system voltage end VDD, and the second end of which is connected to the input end of the light emitting device 40.

[0060] The first node N1 is a node at which the driving switch 11 is connected with the initialization sub-circuit 20 and the writing sub-circuit 30, and the output terminal of the initialization sub-circuit 20 and the output terminal of the writing sub-circuit 30 are both connected with the first node N1. The first system voltage terminal VDD is a power voltage of the pixel driving circuit, and is used to provide a working voltage for the light emitting device 40. Specifically, the voltage of the first system voltage terminal VDD can be set at the first terminal of the driving switch 11, so as to avoid the light emitting device 40 from being lighted in the non-driving state.

[0061] It should be understood that, in actual application, the first terminal of the driving switch 11 can be an input terminal or an output terminal, and correspondingly, the second terminal of the driving switch 11 can be an output terminal or an input terminal. In the embodiment of the present application, the input and output relationship of the first terminal and the second terminal of the driving switch 11 is related to the driving stage in which the pixel driving circuit is located and the compensation mode of the pixel driving circuit in the compensation stage. The specific input and output relationship will be described in subsequent different embodiments, and the present application will not be described here.

[0062] For example, the driving switch 11 is in a transistor structure, the first terminal of the driving switch 11 can be a drain electrode of the transistor, the second terminal of the driving switch 11 can be a source electrode of the transistor, and the control terminal of the driving switch 11 can be a gate electrode of the transistor. The driving switch 11 can receive a signal flowing from the source electrode to the drain electrode, or can receive a signal flowing from the drain electrode to the source electrode, and the present application will not be described here.

[0063] In the embodiment of the present application, the driving switch 11 is configured to turn on the circuit between the first system voltage terminal VDD and the input terminal of the light emitting device 40 in response to the voltage of the first node N1. For example, the light emitting device 40 is an OLED, and the input terminal of the light emitting device 40 can be an anode of the OLED.

[0064] It should be understood that, when the driving switch 11 responds to the voltage of the first node N1, the driving switch 11 responds to the voltage of the first node N1 to turn on the circuit between the first system voltage terminal VDD and the input terminal of the light emitting device 40 only when the voltage difference between the first node N1 and the third node N3 is greater than the threshold voltage of the driving switch 11 (i.e., the threshold value of the control terminal of the driving switch 11). In this way, the driving switch 11 can turn on the circuit after the voltage of the control terminal reaches the threshold value, so as to realize the light emitting control of the light emitting device 40.

[0065] The initialization sub-circuit 20 can be used to reset or initialize the pixel driving circuit, so as to reset the state of the pixel driving circuit. Specifically, the initialization sub-circuit 20 mainly initializes the switch sub-circuit 10, so that the pixel driving circuit is in a known and consistent state before each work, to avoid display problems caused by uncertain state of the pixel driving circuit.

[0066] In the embodiment of the present application, the output end of the initialization sub-circuit 20 is electrically connected with the first node N1, and the input end of the initialization sub-circuit 20 is electrically connected with the initialization signal end Vinit, so that when the pixel driving circuit is initialized, the first node N1 is turned on with the initialization signal end Vinit, thereby initializing the voltage of the first node N1, keeping the state of the pixel driving circuit consistent before driving, and improving the stability of the pixel driving circuit.

[0067] Further, the initialization sub-circuit 20 is also provided with a control end, so that the initialization sub-circuit 20 can receive an initialization control signal to turn on the line between the initialization signal end Vinit and the first node N1, thereby initializing the voltage of the first node N1 by using the signal input by the initialization signal end Vinit.

[0068] The write sub-circuit 30 can be used for writing data, thereby controlling the light emitting intensity of the light emitting device 40 by the data signal. It should be understood that the data writing by the write sub-circuit 30 is independent, that is, the data signal input into the pixel driving circuit can only control the light emitting device 40 driven by the pixel driving circuit, and the writing process of the write sub-circuit 30 will not affect other light emitting devices in the display screen.

[0069] For example, the output end of the write sub-circuit 30 is connected with the first node N1, and the input end of the write sub-circuit 30 is electrically connected with the data signal end Data, so that when the pixel driving circuit is written, the line between the first node N1 and the data signal end Data is turned on, and the data signal input by the data signal end Data can be sent to the control end of the driving switch 11.

[0070] It should be noted that the signals input by the initialization signal end Vinit and the data signal end Data are all voltage signals, and the electronic device can convert the image data into corresponding voltage signals when driving the light emitting device in the display screen, thereby generating corresponding data signals and inputting the data signals into the pixel driving circuit through the data signal end Data to realize the driving of the light emitting device. In this way, the input voltage signal can affect the voltage of the first node N1, so that the voltage of the first node N1 can drive the driving switch 11 to turn on.

[0071] Further, the driving switch 11 can also generate a corresponding driving voltage in response to the data signal input by the data signal end Data, thereby realizing the light emitting control of the light emitting device 40.

[0072] In the embodiment of the present application, the process of driving the light emitting device 40 by the pixel driving circuit can be divided into an initialization process, a compensation process, a writing process and a light emitting process, and the above processes are executed in time sequence. The initialization process can be realized by the initialization sub-circuit 20, the compensation process can be realized by the initialization sub-circuit 20 and the switching sub-circuit 10, the writing process can be realized by the writing sub-circuit 30, and the light emitting process can be realized by the switching sub-circuit 10.

[0073] Specifically, the initialization process is to reset the pixel driving circuit and initialize the voltage of each node in the pixel driving circuit, so as to avoid display problems caused by uncertain state of the pixel driving circuit. The compensation process is to compensate the threshold voltage of the driving switch 11, and utilize the voltage difference between different nodes in the pixel driving circuit to make the driving switch 11 open until the compensation process is completed, and record the compensated threshold voltage Vth in a node, so as to ensure the voltage of the driven light emitting device 40 is accurate and reliable, and improve the display effect and stability of the display screen. By controlling the initialization sub-circuit 20, the voltage of the first node N1 can be initialized and compensated, so as to control the driving switch 11 in the subsequent process.

[0074] The writing process is to convert the image data to be displayed by the electronic device into a voltage type data signal, and input the data signal into the corresponding pixel driving circuit, so as to realize the control of the light emitting device. In the embodiment of the present application, the data signal can be input through the data signal end Data, and then affect the voltage of the first node N1, so as to drive the light emitting device 40 in the light emitting process.

[0075] The light emitting process is the process of driving the light emitting device by the pixel driving circuit. In the embodiment of the present application, after the first node N1 receives the data signal, the switching sub-circuit 10 can respond to the voltage of the first node N1, and turn on and generate a driving current, so as to drive the connected light emitting device 40 to emit light.

[0076] In the embodiment of the present application, the driving process of the light emitting device 40 can include: inputting an initialization control signal through the control end of the initialization sub-circuit 20 to initialize the pixel driving circuit, and then compensating the driving switch 11 by the initialization signal input by the initialization sub-circuit 20 and the signal input by the first system voltage end VDD, so as to control the driving switch 11. In the writing process, the signal input of the data signal end Data can be realized by the writing sub-circuit 30, so as to drive the driving switch 11 to turn on the circuit between the first system voltage end VDD and the light emitting device 40 and generate a corresponding driving current, and then realize the controllable light emitting process of the light emitting device 40.

[0077] FIG. 3 is a structural schematic diagram of a second pixel driving circuit provided by the embodiment of the present application.

[0078] Since the driving switch 11 in the switch sub-circuit 10 is turned on in response to the voltage difference between the first node N1 and the second end of the driving switch 11, the first system voltage end VDD and the input end of the light emitting device 40 can be turned on, and the light emitting device 40 is driven to emit light. However, for a display screen including a plurality of light emitting devices 40, the above driving mode can cause the driving time of different light emitting devices 40 to be inconsistent, thereby causing the display screen to display inconsistently at different positions.

[0079] Therefore, in the pixel driving circuit in the embodiment of the present application, as shown in FIG. 3, the switch sub-circuit 10 further includes a first light emitting control switch 12, which is arranged between the first end of the driving switch 11 and the first system voltage end VDD, thereby isolating the driving switch 11 and the first system voltage end VDD. By controlling the connection between the first system voltage end VDD and the driving switch 11, the light emitting time of the light emitting device 40 can be controlled, thereby improving the consistency of the display screen and improving the viewing experience of the user.

[0080] Further, the first light emitting control switch 12 is also provided with a control end, which can be electrically connected with the light emitting control end EM, thereby receiving the light emitting control signal sent by the light emitting control end EM to control the connection between the first system voltage end VDD and the driving switch 11. Specifically, the first light emitting control switch 12 can turn on the circuit between the first system voltage end VDD and the first end of the driving switch 11 in response to the light emitting control signal.

[0081] It should be understood that, in addition to inputting the light emitting control signal to the first light emitting control switch 12 to control the first light emitting control switch 12 to be turned on, the light emitting control end EM can also input other control signals to the first light emitting control switch 12 to control the first light emitting control switch 12 to be turned off.

[0082] For example, the light emitting control end EM can input a low-level light emitting control signal to the first light emitting control switch 12 to make the first light emitting control switch 12 turn on the circuit between the first system voltage end VDD and the driving switch 11 in response. The light emitting control end EM can also input a high-level light emitting control signal to the first light emitting control switch 12 to make the first light emitting control switch 12 turn off the circuit between the first system voltage end VDD and the driving switch 11 in response.

[0083] It should be noted that the level type and control mode of the signal inputted by the light emitting control terminal EM are only one possible implementation in the embodiments of the present application. In another embodiment of the present application, the first light emitting control switch 12 can also be responsive to the high level light emitting control signal to turn on the circuit between the first system voltage terminal VDD and the driving switch 11, and responsive to the low level light emitting control signal to turn off the circuit between the first system voltage terminal VDD and the driving switch 11. In this embodiment, the light emitting control signal inputted by the light emitting control terminal EM to the first light emitting control switch 12 is a high level signal.

[0084] In the embodiments of the present application, the signal to which the first light emitting control switch 12 is responsive and the response mode of the first light emitting control switch 12 are related to the specific structure of the first light emitting control switch 12. Specifically, if the first light emitting control switch 12 is a transistor, when the first light emitting control switch 12 is a P-type transistor, the first light emitting control switch 12 is turned on in response to a low level signal, and when the first light emitting control switch 12 is an N-type transistor, the first light emitting control switch 12 is turned on in response to a high level signal. The embodiments of the present application do not limit the structure of the first light emitting control switch 12.

[0085] Further, during the initialization process, the initialization sub-circuit 20 can have a plurality of different initialization input terminals to initialize the nodes and the switch sub-circuit 10 in the pixel driving circuit, and the initialization sub-circuit 20 can include a plurality of initialization switches to control the initialization process of the plurality of initialization input terminals and the pixel driving circuit. As shown in FIG. 3, the initialization sub-circuit 20 can include a first initialization switch 21, and a first end of the first initialization switch 21 is electrically connected with the third node N3, a second end of the first initialization switch 21 is electrically connected with a first initialization signal terminal Vinit1, and a control terminal of the first initialization switch 21 is electrically connected with a first control signal terminal scan1.

[0086] The third node N3 is arranged between the second end of the driving switch 11 and the input terminal of the light emitting device 40, and the third node N3 is connected with the first node N1. The first initialization switch 21 can receive the electrical signal of the first control signal terminal scan1 to turn on or turn off the circuit between the first initialization signal terminal Vinit1 and the third node N3.

[0087] For example, the electrical signal inputted by the first control signal terminal scan1 can be a first initialization control signal, and the first initialization switch 21 can turn on the circuit between the first initialization signal terminal Vinit1 and the third node N3 in response to the first initialization control signal. The first initialization signal inputted by the first initialization signal terminal Vinit1 can maintain the voltage of the third node N3, thereby providing the initialization of the third node N3.

[0088] In some embodiments of the present application, the first control signal terminal scan1 can input signals with different levels to the first initialization switch 21 to control the conduction relationship. The first initialization switch 21 can conduct the circuit between the first initialization signal terminal Vinit1 and the first node N1 in response to the high-level first initialization control signal, so as to initialize the first node N1. Further, when the pixel driving circuit performs other operations, the first control signal terminal scan1 can also send a low-level control signal to the first initialization switch 21, so as to drive the first initialization switch 21 to disconnect the circuit between the first initialization signal terminal Vinit1 and the first node N1, thereby completing the initialization process of the pixel driving.

[0089] It should be understood that the type of signal to which the first initialization switch 21 responds in the above embodiments is only an example, and the signal to which the first initialization switch 21 responds in the embodiments of the present application can also be of other types, which are not limited herein.

[0090] In the embodiments of the present application, the output terminal of the light emitting device 40 is electrically connected to the second system voltage terminal VSS, so that a path is formed between the first system voltage terminal VDD and the second system voltage terminal VSS during the light emitting stage, so as to facilitate the light emitting of the light emitting device 40.

[0091] Taking the OLED as the light emitting device 40, the output terminal of the light emitting device 40 connected to the second system voltage terminal VSS is the cathode of the OLED. Since the OLED will conduct and emit light after receiving a certain voltage signal, and the third node N3 is electrically connected to the anode of the OLED, after the first initialization switch 21 is conducted, the first initialization signal input by the first initialization signal terminal Vinit1 will be divided to the anode of the OLED, so that the anode and the cathode of the OLED have a voltage difference. In the embodiments of the present application, the value of Vinit1-VSS needs to be less than the excitation voltage Vop of the OLED, so that the voltage difference between the anode and the cathode of the OLED during the initialization process is less than the excitation voltage Vop of the OLED, thereby avoiding the excitation of the OLED during the initialization to cause display problems, returning the anode potential of the OLED during the last light emitting to a unified initialization voltage, and improving the display effect of the display screen.

[0092] As shown in FIG. 3, the initialization sub-circuit 20 further includes a second initialization switch 22 and a third initialization switch 23 to improve the initialization effect of the initialization sub-circuit 20 and improve the initialization efficiency.

[0093] The first end of the second initialization switch 22 is electrically connected with the first node N1, the second end of the second initialization switch 22 is electrically connected with the second initialization signal terminal Vinit2, and the control end of the second initialization switch 22 is electrically connected with the second control signal terminal scan2. The first end of the third initialization switch 23 is electrically connected with the output end of the write sub-circuit 30, thereby forming the fourth node N4, the second end of the third initialization switch 23 is electrically connected with the third initialization signal terminal Vinit3, and the control end of the third initialization switch 23 is electrically connected with the third control signal terminal scan3. It should be understood that the fourth node N4 is formed by electrically connecting the first end of the third initialization switch 23 with the output end of the write sub-circuit 30, and thus the fourth node N4 can be the position of the connection between the two in the circuit structure shown in FIG. 3, and the specific form is not limited to a point, which is not limited herein.

[0094] In the embodiment of the present application, the fourth node N4 is located between the first node N1 and the third node N3, and the fourth node N4 can be formed by electrically connecting the write sub-circuit 30 and the third initialization switch 23, and in the embodiment of the present application, the voltage of the fourth node N4 is determined by the third initialization signal terminal Vinit3 connected by the write sub-circuit 30 and the third initialization switch 23.

[0095] For example, the second initialization switch 22 can be turned on between the second initialization signal terminal Vinit2 and the first node N1 in response to the second initialization control signal input to the control end from the second control signal terminal scan2. In this way, the voltage of the first node N1 can be initialized to the value of the voltage signal input from the second initialization signal terminal Vinit2 during the initialization of the pixel driving circuit.

[0096] The third initialization switch 23 can be turned on between the third initialization signal terminal Vinit3 and the fourth node N4 in response to the third initialization control signal input from the third control signal terminal scan3. In this way, the voltage of the fourth node N4 can be initialized to the value of the voltage signal input from the third initialization signal terminal Vinit3 during the initialization of the pixel driving circuit.

[0097] It should be noted that the second initialization switch 22 and the third initialization switch 23 can also receive and respond to the control signals input from the second control signal terminal scan2 and the third control signal terminal scan3, respectively, to disconnect and end the input of the initialization signal terminal, thereby completing the initialization process of the pixel driving circuit.

[0098] For example, in some embodiments of the present application, the second control signal terminal scan2 can input signals with different levels to the second initialization switch 22 to control the conduction relationship of the second initialization switch 22. The second initialization switch 22 can conduct the line between the second initialization signal terminal Vinit2 and the first node N1 in response to the high-level second initialization control signal, so as to initialize the first node N1. Further, when the pixel driving circuit performs other operations, the second control signal terminal scan2 can also send a low-level control signal to the second initialization switch 22, so as to drive the second initialization switch 22 to disconnect the line between the second initialization signal terminal Vinit2 and the first node N1, thereby completing the initialization process of the first node N1.

[0099] Similarly, the third control signal terminal scan3 can input signals with different levels to the third initialization switch 23 to control the conduction relationship of the third initialization switch 23. The third initialization switch 23 can conduct the line between the third initialization signal terminal Vinit3 and the fourth node N4 in response to the high-level third initialization control signal, so as to initialize the fourth node N4. Further, when the pixel driving circuit performs other operations, the third control signal terminal scan3 can also send a low-level control signal to the third initialization switch 23, so as to drive the third initialization switch 23 to disconnect the line between the third initialization signal terminal Vinit3 and the fourth node N4, thereby completing the initialization process of the fourth node N4.

[0100] It should be understood that the response of the second initialization switch 22 and the third initialization switch 23 to signals with different levels is only an example in the embodiments of the present application, and the present application does not limit the specific response signal level of the second initialization switch 22 and the third initialization switch 23.

[0101] Continuing to refer to FIG. 3, the write-in sub-circuit 30 can include a write-in switch 31, and the write-in switch 31 has a control terminal to receive a control signal through the control terminal to control the conduction relationship between the data signal terminal Data and the first node N1.

[0102] The input terminal of the write-in switch 31 is the input terminal of the write-in sub-circuit 30, which is electrically connected with the data signal terminal Data, so as to conduct the data signal input by the data signal terminal Data to the first node N1 during the write-in process. Further, the control terminal of the write-in switch 31 can be electrically connected with the write-in control terminal scan4 to receive and respond to the write-in control signal input by the write-in control terminal scan4 before the write-in process is performed, so as to conduct the line between the data signal terminal Data and the first node N1.

[0103] It should be understood that in the scenario where the third initialization switch 23 and the write-in sub-circuit 30 are electrically connected to the fourth node N4, the output of the write-in switch 31 is electrically connected to the fourth node N4 due to the connection between the first node N1 and the fourth node N4, so that the write-in switch 31 is connected to the first node N1 through the fourth node N4.

[0104] In some embodiments of the present application, a storage sub-circuit 50 is further provided in the pixel driving circuit, and the storage sub-circuit 50 is arranged between the first node N1 and the third node N3, for storing the voltage signals input to each node by the initialization sub-circuit 20 during initialization, so that the pixel driving circuit can store the voltage values of the first node N1, the third node N3 and the fourth node N4 after the first initialization switch 21, the second initialization switch 22 and the third initialization switch 23 are turned off, to facilitate subsequent compensation, write-in and light-emitting processes.

[0105] For example, the storage sub-circuit 50 can be arranged between the first node N1 and the fourth node N4 and between the fourth node N4 and the third node N3, for storing the voltage signals input by the first initialization signal terminal Vinit1, the second initialization signal terminal Vinit2 and the third initialization signal terminal Vinit3, respectively. For example, during initialization of the pixel driving circuit, the voltage of the third node N3 is the voltage of the voltage signal input by the first initialization signal terminal Vinit1, the voltage of the fourth node N4 is the voltage of the voltage signal input by the third initialization signal terminal Vinit3, and the voltage of the first node N1 is the voltage of the voltage signal input by the second initialization signal terminal Vinit2. The storage structure of the storage sub-circuit 50 arranged between the first node N1 and the fourth node N4 and between the fourth node N4 and the third node N3 can stabilize and store the voltages of the signals input by the above initialization signal terminals, so as to maintain the working state of the light-emitting device 40 and the voltage difference between the first node N1 and the third node N3, and facilitate the generation of corresponding driving current by the drive switch 11 in subsequent processes.

[0106] FIG. 4 is a driving timing diagram of the circuit in FIG. 3 according to an embodiment of the present application.

[0107] Taking the pixel driving circuit shown in FIG. 3 as an example, the first light-emitting control switch 12 in the pixel driving circuit is low-level on and high-level off, and the other switches in the pixel driving circuit are high-level on and low-level off.

[0108] It should be understood that, in the compensation stage, the voltage at the control end of the driving switch 11 is compensated, which is essentially the voltage difference between the first node N1 and the third node N3. Therefore, the voltage at the first node N1 can be compensated by the second initialization signal terminal Vinit2 and / or the third initialization signal terminal Vinit3 in the compensation process, so that the voltage difference between the first node N1 and the third node N3 meets the threshold voltage of the driving switch 11.

[0109] In some embodiments of the present application, the initialization sub-circuit 20 can cooperate with the first light-emitting control switch 12 to assist the threshold voltage compensation of the driving switch 11.

[0110] For example, the first end of the driving switch 11 is electrically connected to the first light-emitting control switch 12, the second end of the driving switch 11 is electrically connected to the third node N3, and the control end of the driving switch 11 is electrically connected to the first node N1. In the compensation stage, the light-emitting control terminal EM sends a low-voltage signal to the first light-emitting control switch 12 to turn on the first light-emitting control switch 12, so that the first system voltage terminal VDD compensates the voltage of the third node N3. Because the storage sub-circuit 50 is arranged between the first node N1 and the third node N3, the signal of the first system voltage terminal VDD does not directly affect the first node N1, but changes the voltage difference between the first node N1 and the third node N3.

[0111] Further, in order to make the voltage difference between the first node N1 and the third node N3 meet the threshold voltage of the driving switch 11, the first node N1 can also be compensated by the second initialization switch 22 or the third initialization switch 23. For example, in the compensation stage, the first initialization switch 21 is turned off, and the second initialization switch 22 and / or the third initialization switch 23 are turned on, so as to control the voltage difference between the first node N1 and the third node N3.

[0112] Therefore, in the embodiments of the present application, when the first light-emitting control switch 12 and at least one of the second initialization switch 22 and the third initialization switch 23 are turned on at the same time, the system voltage input by the first system voltage terminal VDD is transmitted to the third node N3 through the driving switch 11.

[0113] The initialization sub-circuit 20 can also transmit the initialization signal inputted by the second initialization signal terminal Vinit2 and / or the third initialization signal terminal Vinit3 to the first node N1 when the first light-emitting control switch 12 and at least one of the second initialization switch 22 and the third initialization switch 23 are turned on at the same time, so as to compensate the threshold voltage of the driving switch 11. In this way, the threshold voltage of the driving switch 11 can be compensated by using the first system voltage terminal VDD and at least one of the second initialization signal terminal Vinit2 and the third initialization signal terminal Vinit3, so that the threshold voltage compensation can be realized by the initialization sub-circuit 20 and the switch sub-circuit 10 without setting additional switches for compensation, thereby improving the driving efficiency of the pixel driving circuit.

[0114] As shown in (a) and (b) of FIG. 4, in the initialization stage of the pixel driving circuit, the first control signal terminal scan1, the second control signal terminal scan2 and the third control signal terminal scan3 output high voltage signals to the switches electrically connected thereto, so as to control the switches to be turned on, i.e., the first initialization switch 21, the second initialization switch 22 and the third initialization switch 23 are turned on. The voltage signal inputted by the first initialization signal terminal Vinit1 initializes the voltage of the third node N3, the voltage signal inputted by the second initialization signal terminal Vinit2 initializes the voltage of the first node N1, and the voltage signal inputted by the third initialization signal terminal Vinit3 initializes the voltage of the fourth node N4.

[0115] In the compensation stage, as shown in (a) of FIG. 4, the first control signal terminal scan1 and the third control signal terminal scan3 can switch the voltage signals outputted thereby to low voltage signals, so as to turn off the first initialization switch 21 and the third initialization switch 23, while the second control signal terminal scan2 still maintains the state of outputting high voltage signals, so as to keep the second initialization switch 22 in the turned-on state, thereby maintaining the voltage of the first node N1 at the voltage of the voltage signal inputted by the second initialization signal terminal Vinit2. Taking the voltage of the voltage signal inputted by the second initialization signal terminal Vinit2 as Vinit2 for example, the voltage of the first node N1 is maintained at the level of Vinit2 during the initialization and compensation processes of the pixel driving circuit.

[0116] Meanwhile, in the compensation stage, the light emitting control terminal EM outputs a low voltage signal, thereby turning on the first light emitting control switch 12, so that the voltage of the first system voltage terminal VDD is loaded to the third node N3. At this time, the voltage signal inputted by the first system voltage terminal VDD flows through the driving switch 11 to compensate the voltage difference between the first node N1 and the third node N3. In the compensation process, the second initialization signal terminal Vinit2 always maintains the voltage of the first node N1 by inputting the voltage signal. At this time, the potential of one end of the driving switch 11 is Vinit2-Vth.

[0117] It should be understood that the value of Vth is the threshold voltage of the driving switch 11, which is the minimum voltage received by the control terminal when the driving switch 11 is turned on. In the embodiment of the present application, by adjusting the inputted initialization signal in the compensation stage and the signal inputted by the first system voltage terminal VDD, the voltage difference between the first node N1 and the third node N3 is Vth, thereby realizing that the potential of the second end of the driving switch 11 in the compensation stage of the above-mentioned embodiment is Vinit2-Vth.

[0118] Similarly, as shown in (b) of FIG. 4, which is similar to the timing shown in (a) of FIG. 4, only the second initialization switch 22 opened in the compensation stage is replaced by the third initialization switch 23. In this compensation process, the voltage of the first node N1 is compensated by the third initialization signal terminal Vinit3, thereby controlling the voltage difference between the first node N1 and the third node N3 for compensation. The specific compensation process is the same as the foregoing steps, which will not be described here in detail.

[0119] In the stage of writing by the pixel driving circuit, the write control signal terminal scan4 outputs a high voltage signal to the write switch 31, thereby turning on the data signal terminal Data and the fourth node N4, and making the light emitting control terminal EM output a high voltage signal, and making the second control signal terminal scan2 and the third control signal terminal scan3 output a low voltage signal, thereby turning off the first light emitting control switch 12, the second initialization switch 22 and the third initialization switch 23. At this time, the voltage variation of the fourth node N4 is Data-Vinit3, and the voltage variation also causes the voltage of the first node N1 and the third node N3 to change.

[0120] In the embodiments of the present application, the two storage structures in the storage sub-circuit 50 can be the same or different, which is not limited in the present application. The storage sub-circuit 50 is configured to couple the voltage of the fourth node N4 to the first node N1 and the third node N3 in the writing process, and since the third node N3 is electrically connected with the light emitting device 40, it will participate in voltage division, so that the voltage variation of the first node N1 and the third node N3 is different, and the voltage variation of the first node N1 and the third node N3 is related to the voltage of the voltage signal input by the data signal end Data.

[0121] Further, in the light emitting stage, the outputs of all the control signal ends can be set as low voltage, so that all the switches directly connected with the control signal ends are in the off state except the first light emitting control switch 12 which is in the on state. At this time, the driving switch 11 is affected by the voltages of the first node N1, the third node N3 and the fourth node N4, and is turned on to generate a corresponding driving current to drive the light emitting device 40 to emit light.

[0122] For example, the calculation formula of the driving current I can be I = 0.5 x k x (Vgs-Vth)^2, wherein k is related to the device characteristics of the driving switch 11, and for example, when the driving switch 11 is an N-type transistor, k represents the product of the current gain coefficient of the transistor and the aspect ratio of the transistor, Vgs is the voltage between the gate (G) and the source (S) of the driving switch 11, and Vth is the threshold voltage of the driving switch 11. It should be understood that the transistor in the N-type transistor of the driving switch 11 is a thin film field effect transistor, i.e. TFT.

[0123] In the embodiments, the gate G of the driving switch 11 is the control end of the driving switch 11, and the source S of the driving switch 11 is the second end of the driving switch 11. Since the voltage of the second end of the driving switch 11 is Vinit2-Vth in the compensation stage, the threshold voltage Vth is eliminated in the actual calculation of the driving current I, and the specific value of the driving current I output by the driving switch 11 is related to the voltage values of the first node N1, the third node N3, the fourth node N4 and Data.

[0124] In some embodiments of the present application, as shown in (c) of FIG. 4, when the pixel driving circuit performs compensation, the signals output by the first control signal end scan1 and the light emitting control end EM can be adjusted to low voltage signals, so that the second control signal end scan2 and the third control signal end scan3 maintain output of high voltage signals, so that the second initialization switch 22 and the third initialization switch 23 are in the on state in the compensation stage, and then the voltage compensation is performed. The compensation process, the subsequent writing process and the light emitting process in the embodiments of the present application are similar to the foregoing embodiments, and the remaining steps will not be described herein.

[0125] FIG. 5 is a structural schematic diagram of a third pixel driving circuit according to an embodiment of the present application.

[0126] In some embodiments of the present application, the compensation process of the pixel driving circuit can also be implemented in other ways. For example, as shown in FIG. 5, the pixel driving circuit can further include a first compensation switch 61, and a first end of the first compensation switch 61 is electrically connected with the first node N1, and a second end of the first compensation switch 61 is electrically connected with the second node N2. The second node N2 is arranged between the first end of the driving switch 11 and the first system voltage terminal VDD.

[0127] It should be understood that the first compensation switch 61 also has a control end to control the first compensation switch 61. Specifically, the control end of the first compensation switch 61 can be electrically connected with the compensation control terminal scan5 to receive the compensation control signal output by the compensation control terminal scan5, so as to turn on the first node N1 and the second node N2, thereby compensating the threshold voltage of the driving switch 11. Further, the control end of the first compensation switch 61 can also receive the voltage signal of other levels of the compensation control terminal scan5 to turn off, so as to isolate the first node N1 and the second node N2 in the non-compensation stage. The first compensation switch 61 can be turned on or turned off by receiving and responding to the voltage signal output by the compensation control terminal scan5, thereby realizing the function of compensating the first node N1.

[0128] In some embodiments of the present application, in order to store the input voltage signal in the initialization process respectively, the storage structure in the storage sub-circuit 50 can be a capacitor. For example, the storage sub-circuit 50 can include two capacitors, i.e., a first capacitor C1 and a second capacitor C2. The first capacitor C1 is arranged between the first node N1 and the fourth node N4, and the second capacitor C2 is arranged between the third node N3 and the fourth node N4.

[0129] FIG. 6 is a first driving timing diagram of the circuit in FIG. 5 according to an embodiment of the present application.

[0130] It should be understood that the driving process of the pixel driving circuit shown in FIG. 5 is the same as the foregoing embodiments, and the present application will not be repeated here.

[0131] Taking the pixel driving circuit shown in FIG. 5 as an example, the first light-emitting control switch 12 is low-level on and high-level off, and other switches in the pixel driving circuit are high-level on and low-level off. As shown in FIG. 5 and FIG. 6, in the initialization stage, the first control signal end scan1, the second control signal end scan2 and the third control signal end scan3 all output high-level voltage signals as control signals, thereby controlling the first initialization switch 21, the second initialization switch 22 and the third initialization switch 23 to be on, respectively, to complete the initialization process.

[0132] In the initialization process, the voltage of the first node N1 is initialized to the voltage of the signal output by the second initialization signal end Vinit2, the voltage of the fourth node N4 is initialized to the voltage of the signal output by the third initialization signal end Vinit3, and the voltage of the third node N3 is initialized to the voltage of the signal output by the first initialization signal end Vinit1.

[0133] Taking the position of the first node N1 shown in FIG. 5 as an example, the plate of the first capacitor C1 and the second capacitor C2 closer to the first node N1 is the upper plate, and the plate farther away from the first node N1 is the lower plate. In the initialization process, the upper plate voltage of the first capacitor C1 is Vinit2, the lower plate voltage is Vinit3, the upper plate voltage of the second capacitor C2 is Vinit3, and the lower plate voltage is Vinit1.

[0134] In the compensation stage, when the compensation control end scan5 outputs a high-level voltage signal to control the first compensation switch 61 to be on, a signal end is also needed to provide a voltage for the compensation process. For example, the first end of the driving switch 11 is electrically connected to the second node N2, the second end of the driving switch 11 is electrically connected to the third node N3, and the control end of the driving switch 11 is electrically connected to the first node N1. According to the connection relationship, the first initialization signal end Vinit1 can be used for compensation.

[0135] In the compensation stage, the outputs of the second control signal end scan2 and the third control signal end scan3 are converted to low-level signals, thereby turning off the second initialization switch 22 and the third initialization switch 23, thereby controlling the pixel driving circuit to compensate. At this time, the fourth node N4 is in a floating state, where the floating state means that the circuit node is neither explicitly connected to a high level (such as the first system voltage end VDD) nor explicitly connected to a low level (such as the second system voltage end VSS or ground GND), but is in a potential holding state without a direct current voltage to continuously stabilize the voltage.

[0136] When the fourth node N4 is in the floating state, the first capacitor C1 and the second capacitor C2 stabilize the two nodes to reduce the instability of the current flow in the floating state. In the floating state, the voltage state of the fourth node N4 is affected by the voltages of the first capacitor C1 and the second capacitor C2. As can be seen from the voltages of the first capacitor C1 and the second capacitor C2 in the initialization stage, the first capacitor C1 and the second capacitor C2 can stabilize the voltage of the fourth node N4 to the state after the end of the initialization stage.

[0137] In this process, the switch sub-circuit 10 can transmit the first initialization signal input by the first initialization signal terminal Vinit1 to the first node N1 through the driving switch 11 to compensate the threshold voltage of the driving switch 11 in response to the simultaneous conduction of the first initialization switch 21 and the first compensation switch 61. In this way, the compensation process of the threshold voltage of the driving switch 11 can be completed by using the first initialization signal terminal Vinit1, and the response efficiency of the driving switch 11 is improved. In this embodiment, the driving switch 11 can be a TFT, in which the first end is the drain, the second end is the source, and the control end is the gate. The compensation process of the driving switch 11 is essentially a process of compensating the voltage difference between the gate and the source of the driving switch 11.

[0138] Further, in the writing process, the output of the compensation control terminal scan5 can be converted to a low-level signal to turn off the first compensation switch 61, and the outputs of the writing control terminal scan4 and the first control signal terminal scan1 can be converted to high-level voltage signals. In response to the high-level voltage signal output by the writing control terminal scan4, the writing switch 31 is turned on to enable the data signal terminal Data to input the data signal, and in response to the high-level voltage signal output by the first control signal terminal scan1, the first initialization switch 21 is turned on to stabilize the third node N3 by using the first initialization signal terminal Vinit1.

[0139] At this time, the first node N1 and the third node N3 also receive the data signal coupled by the first capacitor C1 and the second capacitor C2, so in the writing stage, the voltage difference between the first node N1 and the third node N3 is greater than the threshold voltage Vth of the driving switch 11.

[0140] It should be understood that in the embodiments of the present application, the voltage difference between the voltage of the signal input by the second initialization signal terminal Vinit2 to the pixel driving circuit and the voltage of the signal input by the first initialization signal terminal Vinit1 to the pixel driving circuit can be greater than the threshold voltage Vth of the driving switch 11, so that the voltage difference between the first node N1 and the third node N3 can meet the requirements of the threshold voltage Vth of the driving switch 11.

[0141] In some embodiments, the voltage of the signal inputted into the second initialization signal terminal Vinit2 can also be greater than or equal to the voltage of the signal inputted into the third initialization signal terminal Vinit3, so that the voltage of the upper plate of the first capacitor C1 is greater than the voltage of the lower plate, and the voltage of the signal inputted into the third initialization signal terminal Vinit3 is also required to be less than the voltage of the data signal inputted into the data signal terminal Data in the writing stage, so that the voltage of the first node N1 is raised after being coupled and divided, and the requirement that the voltage difference between the first node N1 and the third node N3 is greater than the threshold voltage Vth of the driving switch 11 is met in the writing stage.

[0142] It should be understood that the above-mentioned voltage of the signal inputted into the first initialization signal terminal Vinit1, the second initialization signal terminal Vinit2 and the third initialization signal terminal Vinit3 to the pixel driving circuit is only one of the feasible embodiments in the present application. In some embodiments, the threshold voltage Vth of the driving switch 11 can be negative, that is, the driving switch 11 can also be controlled to be turned on when the voltage difference between the first node N1 and the third node N3 is negative. Further, the voltage of the signal inputted into the second initialization signal terminal Vinit2 can also be less than the voltage of the signal inputted into the third initialization signal terminal Vinit3. Therefore, the present application does not limit the voltage of the signal inputted into the first initialization signal terminal Vinit1, the second initialization signal terminal Vinit2 and the third initialization signal terminal Vinit3 to the pixel driving circuit.

[0143] In the light emitting stage, the output of all the control signal terminals can be set to low voltage, so that all the switches directly connected with the control signal terminals are in the off state except for the first light emitting control switch 12 which is turned on. At this time, the driving switch 11 is affected by the voltages of the first node N1, the third node N3 and the fourth node N4, and is turned on to generate a corresponding driving current to drive the light emitting device 40 to emit light.

[0144] Further, the calculation formula and method of the driving current I can refer to the foregoing embodiments, which will not be repeated here.

[0145] FIG. 7 is a second driving timing diagram of the circuit in FIG. 5 provided by the embodiments of the present application.

[0146] In some embodiments of the present application, compared with the driving timing shown in FIG. 6, in some embodiments, as shown in FIG. 7, the third initialization signal terminal Vinit3 can maintain the state of inputting the initialization signal in the compensation stage, so as to stabilize the voltage of the fourth node N4, so that the fourth node is not in the floating state, but in the stable state in the compensation stage, so as to better compensate the pixel driving circuit and improve the driving efficiency of the pixel driving circuit.

[0147] It should be understood that the processes of other steps in the embodiment are the same as the driving timing shown in FIG. 6, and the present application does not repeat them here.

[0148] In the embodiment of the present application, the control signal terminals for controlling the switches in the pixel driving circuit, i.e., the first control signal terminal scan1, the second control signal terminal scan2, the third control signal terminal scan3, the write control terminal scan4, the compensation control terminal scan5, etc., are connected to the scanning circuit in the display screen, and therefore the increase of the control signal terminals will also affect the complexity of the scanning circuit in the display screen.

[0149] Therefore, in the embodiment of the present application, the levels of the uniformly input control signals are used to enable different control signal terminals to access the same output terminal of the scanning circuit, thereby reducing the number of connections between the scanning circuit and the pixel driving circuit and lowering the complexity of the circuit.

[0150] In the embodiment of the present application, as shown in FIGS. 6 and 7, the first control signal terminal scan1 has the same trend of level change of the control signal of the light-emitting control terminal EM, and the first control signal terminal scan1 and the light-emitting control terminal EM can share the signal, which can improve the synchronization of the turn-on and turn-off of the first control signal terminal scan1 and the light-emitting control terminal EM, and reduce the input terminals of the scanning circuit and the complexity of the pixel driving circuit.

[0151] FIG. 8 is a third and fourth driving timing diagram of the circuit in FIG. 5 provided by the embodiment of the present application.

[0152] As shown in (a) of FIG. 8, the driving timing is similar to that shown in FIG. 6, and the difference is that the first initialization switch 21 is in the off state in the write stage, so as to stabilize the third node N3 in the compensation stage and make the third node N3 in the floating state in the write stage. At this time, the second control signal terminal scan2 and the third control signal terminal scan3 have the same trend of level change of the signal, and therefore the second control signal terminal scan2 and the third control signal terminal scan3 can share the signal, which can improve the synchronization of the turn-on and turn-off of the second initialization switch 22 and the third initialization switch 23, and reduce the complexity of the pixel driving circuit.

[0153] As shown in (b) of FIG. 8, the driving timing is similar to that shown in (a) of FIG. 8, except that the third initialization switch 23 is in the on state in the compensation stage, so as to stabilize the fourth node N4 in the compensation stage. At this time, the level change trend of the signals input to the pixel driving circuit from the first control signal end scan1 and the third control signal end scan3 is the same, so the first control signal end scan1 and the third control signal end scan3 can share the signal, improving the synchronization of the on and off of the first initialization switch 21 and the third initialization switch 23, and reducing the complexity of the pixel driving circuit.

[0154] It should be noted that the driving timing of the pixel driving circuit described above is only one of the possible embodiments in the present application, and the present application does not limit the specific driving timing of the pixel driving circuit.

[0155] FIG. 9 is a structural schematic diagram of a fourth pixel driving circuit provided by an embodiment of the present application.

[0156] As shown in FIG. 9, the pixel driving circuit can further include a second compensation switch 71, and the output end of the second compensation switch 71 is electrically connected with the fifth node N5, and the input end of the second compensation switch 71 is electrically connected with the compensation signal end Vbias.

[0157] The fifth node N5 is arranged between the second end of the driving switch 11 and the third node N3. Further, the second compensation switch 71 can be turned on or off by receiving and responding to the voltage signal output from the compensation control end scan5, so as to send the signal input from the compensation signal end Vbias to the fifth node N5. That is, the second compensation switch 71 can turn on the circuit between the compensation signal end Vbias and the fifth node N5 in response to the compensation control signal sent by the compensation control end scan5.

[0158] In the present embodiment, the driving switch 11 is in the transistor structure, the first end (i.e. the drain) of the driving switch 11 is electrically connected with the second node N2, the second end (i.e. the source) of the driving switch 11 is electrically connected with the fifth node N5, and the control end (i.e. the gate) of the driving switch 11 is electrically connected with the first node N1. In the compensation stage, the compensation control end scan5 can output a voltage signal to control the first compensation switch 61 and the second compensation switch 71 to be turned on, so as to transmit the compensation signal input from the compensation signal end Vbias to the first node N1 through the driving switch 11, to compensate the threshold voltage of the driving switch 11. In this way, the threshold voltage can be compensated by using the compensation signal end Vbias, so that the first initialization signal can be set to a negative value, to optimize the compensation effect of the driving switch.

[0159] In the embodiments of the present application, the source and the drain of the driving switch 11 are alternately applied. That is, in the compensation stage, the compensation signal input by the compensation signal terminal Vbias is allowed to flow through the driving switch 11 from the source to the drain, so as to reach the second node N2, and the Vbias is compensated to the first node N1 through the first compensation switch 61. In the light emitting stage, the system voltage input by the first system voltage terminal VDD is allowed to flow from the drain to the source, so as to drive the light emitting device 40 to emit light.

[0160] Further, since the fifth node N5 is located between the driving switch 11 and the light emitting device 40, the compensation signal input by the compensation signal terminal Vbias is transmitted to the light emitting device 40, thereby affecting the normal operation of the light emitting device 40.

[0161] Therefore, in some embodiments, the switch sub-circuit 10 further comprises a second light emitting control switch 13, which is arranged between the second end of the driving switch 11 and the input end of the light emitting device 40. The second light emitting control switch 13 is configured to turn on the circuit between the second end of the driving switch 11 and the input end of the light emitting device 40 in response to a light emitting control signal.

[0162] For example, the second light emitting control switch 13 also has a control end to receive a control signal to realize turn-on or turn-off. Since the first light emitting control switch 12 and the second light emitting control switch 13 are turned on at the same time, the first light emitting control switch 12 and the second light emitting control switch 13 can be connected to the same light emitting control end EM to receive the light emitting control signal sent by the light emitting control end EM.

[0163] Further, since the control ends of the first light emitting control switch 12 and the second light emitting control switch 13 are connected to the same signal, the response signals of the first light emitting control switch 12 and the second light emitting control switch 13 are the same. For example, if the first light emitting control switch 12 and the second light emitting control switch 13 are both transistor structures, the transistors can both be P-type transistors, or both be N-type transistors. In this way, the problem that the light emitting control end EM cannot control the first light emitting control switch 12 and the second light emitting control switch 13 at the same time due to the structural difference between the first light emitting control switch 12 and the second light emitting control switch 13 can be avoided.

[0164] In the embodiments of the present application, the material of the transistors of the first light emitting control switch 12 and the second light emitting control switch 13 can include IGZO. In the embodiments of the present application, the first initialization switch 21, the second initialization switch 22, the third initialization switch 23, the write-in switch 31, the first compensation switch 61, and the second compensation switch 71 can all be transistors, specifically, N-type transistors.

[0165] If the partial switch adopts P-type transistor, the high potential in the control signal can be replaced by low potential, and the low potential can be replaced by high potential to realize the control, which will not be described herein.

[0166] FIG. 10 is a first to fourth driving timing diagram of the circuit in FIG. 9 provided by the embodiment of the present application.

[0167] In the embodiment, as shown in (a) of FIG. 10, the second initialization switch 22 and the third initialization switch 23 are connected to the same signal, i.e., scan2. Therefore, the driving timing in the embodiment can refer to the driving timing shown in (a) of FIG. 8, which will not be described herein.

[0168] In the embodiment, the compensation signal terminal Vbias replaces the first initialization signal terminal Vinit1 to play the effect of compensating voltage, and the first initialization signal terminal Vinit1 can be connected to the third node N3 in the compensation stage, so as to maintain the voltage of the third node N3. The compensation signal terminal Vbias is decoupled from the voltage of the second system voltage terminal VSS. In order to compensate the effect, the second system voltage terminal VSS can be set to a negative value. In the compensation stage, the voltage difference between the first node N1 and the third node N3 can be Vbias+Vth, so that the coupling starting point of the first node N1 is lowered, the starting point of the fourth node N4 is lowered, and the voltage of the signal input by the data signal terminal Data is also lowered, thereby improving the sensitivity of the driving.

[0169] In some embodiments, as shown in (b) of FIG. 10, compared with the timing shown in (a) of FIG. 10, the first control signal terminal scan1 can output a high-level signal in the compensation stage and the writing stage, so as to connect the first initialization switch 21 in the compensation stage and the writing stage to stabilize the voltage of the third node N3. By setting the control timing, the first control signal terminal scan1 and the control signal of the light-emitting control terminal EM can have the same level change trend, the first control signal terminal scan1 and the light-emitting control terminal EM can share the signal, and the access of the scanning signal is reduced.

[0170] In some embodiments of the present application, because the compensation signal terminal Vbias can compensate, in the compensation stage, the first initialization switch 21 can be in the closed state, i.e., the first control signal terminal scan1 inputs a low-level signal to control the first initialization switch 21 to be turned off, so that the control terminals of the first initialization switch 21, the second initialization switch 22 and the third initialization switch 23 share the signal, and the access of the scanning signal is reduced.

[0171] It should be understood that the second initialization switch 22 and the third initialization switch 23 can also be connected to two control signal terminals, i.e., scan2 and scan3, respectively, so as to realize control respectively. As shown in (c) and (d) of FIG. 10, the third control signal terminal scan3 can also input a high-level signal in the compensation stage, so as to stabilize the fourth node N4, thereby improving the compensation effect.

[0172] On the basis of the pixel driving circuit provided in the above-mentioned embodiments, the present application further provides a display panel, which comprises a plurality of pixel driving circuits as in any one of the above-mentioned embodiments, and a light emitting device connected to each pixel driving circuit. For example, the structure of the display panel can be the same as that shown in FIG. 1, and the present application will not be described here.

[0173] FIG. 11 is a schematic diagram of an electronic device provided in an embodiment of the present application.

[0174] Further, the present application further provides an electronic device 100, as shown in FIG. 11, which can comprise a housing 101, and a display panel 102 as in the above-mentioned embodiments, wherein the display panel 102 is mounted on the housing 101.

[0175] It can be understood that the structure shown in the embodiment does not constitute a specific limitation on the electronic device. In other embodiments, the electronic device can comprise more or fewer components than those described above, or combine certain components, or split certain components, or different arrangement of components. The above-mentioned components can be realized by hardware, software or a combination of software and hardware.

[0176] In some embodiments, the electronic device 100 can comprise 1 or N display panels 102, wherein N is a positive integer greater than 1.

[0177] Through the description of the above embodiments, those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional modules is taken as an example for illustration, and in actual application, the above functions can be completed by different functional modules according to needs, i.e., the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.

[0178] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. For example, the embodiments of the apparatus described above are merely schematic, and the division of the modules or units is merely logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, or the among different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0179] The units described as separated components can or can not be physically separated, and the components displayed as units can be located in one place or can be distributed to multiple places. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0180] In addition, each functional unit in the embodiments of the present application can be integrated in a processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in one unit. The integrated unit can be implemented in the form of hardware, or in the form of a software functional unit.

[0181] The above is merely specific embodiments of the present application, and the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A pixel driving circuit, characterized by comprising: The circuit comprises a switching sub-circuit, an initialization sub-circuit and a writing sub-circuit. The switching sub-circuit comprises a driving switch, a control end of the driving switch is electrically connected with a first node, a first end of the driving switch is connected with a first system voltage end, a second end of the driving switch is connected with an input end of the light emitting device, and the driving switch is configured to turn on a line between the first system voltage end and the input end of the light emitting device in response to a voltage of the first node. The initialization sub-circuit comprises an input end electrically connected with an initialization signal end, an output end electrically connected with the first node, and the initialization sub-circuit is configured to initialize the voltage of the first node by using a signal input from the initialization signal end in response to an initialization control signal. The writing sub-circuit comprises an output end connected with the first node, an input end electrically connected with a data signal end, and the writing sub-circuit is configured to turn on a line between the data signal end and the first node in response to a writing control signal.

2. The pixel driving circuit of claim 1, wherein The writing sub-circuit comprises a writing switch, a control end of the writing switch is electrically connected with a writing control end, an input end of the writing switch is electrically connected with the data signal end, an output end of the writing switch is connected with the first node, and the writing switch is configured to turn on the line between the data signal end and the first node in response to the writing control signal input from the writing control end.

3. The pixel driving circuit of claim 1, wherein The initialization sub-circuit comprises a first initialization switch, a first end of the first initialization switch is electrically connected with a third node, a second end of the first initialization switch is electrically connected with a first initialization signal end, a control end of the first initialization switch is electrically connected with a first control signal end, the third node is arranged between the second end of the driving switch and the input end of the light emitting device, and the third node is connected with the first node. The first initialization switch is configured to turn on a line between the first initialization signal end and the first node in response to a first initialization control signal input from the first control signal end.

4. The pixel driving circuit of claim 3, wherein The circuit further comprises a first compensation switch, a first end of the first compensation switch is electrically connected with the first node, a second end of the first compensation switch is electrically connected with a second node, and the second node is arranged between the first end of the driving switch and the first system voltage end. The first compensation switch is configured to turn on the first node and the second node in response to a compensation control signal to compensate a threshold voltage of the driving switch.

5. The pixel driving circuit of claim 4, wherein The first end of the driving switch is electrically connected with the second node, the second end of the driving switch is electrically connected with the third node, and the control end of the driving switch is electrically connected with the first node. The switch sub-circuit is further configured to, in response to the first initialization switch and the first compensation switch being turned on at the same time, transmit a first initialization signal input by the first initialization signal terminal to the first node through the drive switch, so as to compensate for a threshold voltage of the drive switch. 6.The pixel driving circuit of claim 3, wherein, the initialization sub-circuit further comprises a second initialization switch and a third initialization switch; the first end of the second initialization switch is electrically connected with the first node, the second end of the second initialization switch is electrically connected with a second initialization signal terminal, and the control end of the second initialization switch is electrically connected with a second control signal terminal; the second initialization switch is configured to, in response to a second initialization control signal input by the second control signal terminal, turn on a line between the second initialization signal terminal and the first node; the first end of the third initialization switch is connected with the output terminal of the write sub-circuit to form a fourth node, the second end of the third initialization switch is electrically connected with a third initialization signal terminal, and the control end of the third initialization switch is electrically connected with a third control signal terminal; the third initialization switch is configured to, in response to a third initialization control signal input by the third control signal terminal, turn on a line between the third initialization signal terminal and the fourth node. 7.The pixel driving circuit of claim 6, wherein, the circuit further comprises a storage sub-circuit, the storage sub-circuit is arranged between the first node and the third node, and the storage sub-circuit is configured to stabilize the first node, the third node and the fourth node after the initialization sub-circuit is initialized. 8.The pixel driving circuit of claim 7, wherein, the storage sub-circuit comprises a first capacitor and a second capacitor, the first capacitor is arranged between the first node and the fourth node, and the second capacitor is arranged between the third node and the fourth node. 9.The pixel driving circuit of claim 6, wherein, a difference between a voltage of a signal input by the second initialization signal terminal and a voltage of a signal input by the first initialization signal terminal is greater than a threshold voltage of the drive switch. 10.The pixel driving circuit of claim 4, wherein, the circuit further comprises a second compensation switch, an output terminal of the second compensation switch is electrically connected with a fifth node, an input terminal of the second compensation switch is electrically connected with a compensation signal terminal, and the fifth node is arranged between the second end of the drive switch and the third node; the second compensation switch is configured to, in response to a compensation control signal, turn on a line between the compensation signal terminal and the fifth node; the first end of the drive switch is electrically connected with the second node, the second end of the drive switch is electrically connected with the fifth node, and the control end of the drive switch is electrically connected with the first node. The switch sub-circuit is further configured to, in response to the first compensation switch and the second compensation switch being turned on at the same time, transmit a compensation signal input by the compensation signal terminal to the first node through the drive switch, so as to compensate for a threshold voltage of the drive switch. 11.The pixel driving circuit of claim 6, wherein, The switch sub-circuit further comprises a first light-emitting control switch, which is arranged between the first end of the drive switch and the first system voltage terminal, and is configured to, in response to a light-emitting control signal, turn on a line between the first system voltage terminal and the first end of the drive switch. 12.The pixel driving circuit of claim 11, wherein, The first end of the drive switch is electrically connected to the first light-emitting control switch, the second end of the drive switch is electrically connected to the third node, and the control end of the drive switch is electrically connected to the first node; The switch sub-circuit is further configured to, in response to the first light-emitting control switch and at least one of the second initialization switch and the third initialization switch being turned on at the same time, transmit a system voltage input by the first system voltage terminal to the third node through the drive switch; The initialization sub-circuit is further configured to, in response to the first light-emitting control switch and at least one of the second initialization switch and the third initialization switch being turned on at the same time, transmit an initialization signal input by the second initialization signal terminal and / or the third initialization signal terminal to the first node, so as to compensate for a threshold voltage of the drive switch. 13.The pixel driving circuit of claim 11, wherein, The switch sub-circuit further comprises a second light-emitting control switch, which is arranged between the second end of the drive switch and the input terminal of the light-emitting device, and is configured to, in response to the light-emitting control signal, turn on a line between the second end of the drive switch and the input terminal of the light-emitting device. 14.The pixel driving circuit of claim 13, wherein, The first light-emitting control switch and the second light-emitting control switch are both transistors; The transistors are P-type transistors; or The transistors are N-type transistors.

15. A display panel, characterized by A display panel comprising a plurality of pixel driving circuits as claimed in any one of claims 1 to 14, and a light-emitting device connected to each of the pixel driving circuits.

16. A display device, characterized by The display panel comprises: a housing; the display panel as claimed in claim 15 is mounted on the housing.

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