Display device, pixel driving circuit and control method of pixel driving circuit

Abstract

The invention relates to a display device, a pixel driving circuit and a control method of the pixel driving circuit. The pixel driving circuit comprises a voltage write-in circuit, an input end of the voltage write-in circuit is connected with a pulse amplitude modulation signal; the input end of the voltage holding circuit is connected with the output end of the voltage write-in circuit; the input end of the voltage compensation circuit is connected with the output end of the voltage holding circuit, and the voltage compensation circuit is configured to drive a light-emitting device in a light-emitting circuit; and the input end of the light-emitting circuit is connected with a pulse width modulation signal, and a light-emitting device in the light-emitting circuit emits light under the driving of the voltage compensation circuit and the control of the pulse width modulation signal. The pixel driving circuit can improve the uniformity of the display brightness of the light-emitting device.

Description

Technical Field

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

[0002] Micro LEDs (light-emitting diodes) have gradually become commonly used light-emitting devices in display devices due to their self-emissive properties.

[0003] Currently, the current flowing through a Micro LED is typically controlled using PAM (Pulse Amplitude Modulation) or PWM (Pulse Width Modulation), thereby controlling the brightness of the Micro LED.

[0004] However, since the light-emitting current of Micro LEDs is usually small, it is difficult to control the display brightness of Micro LEDs by precisely controlling the current of Micro LEDs, which results in poor uniformity of the display brightness of Micro LEDs. Summary of the Invention

[0005] Therefore, it is necessary to provide a display device, a pixel driving circuit, and a control method for the pixel driving circuit that can improve the uniformity of the brightness of the light-emitting device.

[0006] In a first aspect, a display device is provided, the display device including a pixel driving circuit, wherein...

[0007] The pixel driving circuit includes:

[0008] A voltage writing circuit, wherein the input terminal of the voltage writing circuit is connected to a pulse amplitude modulation signal;

[0009] A voltage holding circuit, wherein the input terminal of the voltage holding circuit is connected to the output terminal of the voltage writing circuit;

[0010] A voltage compensation circuit, wherein the input terminal of the voltage compensation circuit is connected to the output terminal of the voltage holding circuit, and the voltage compensation circuit is configured to drive the light-emitting device in the light-emitting circuit;

[0011] A light-emitting circuit, wherein the input terminal of the light-emitting circuit is connected to a pulse width modulation signal, and the light-emitting device in the light-emitting circuit emits light under the drive of the voltage compensation circuit and under the control of the pulse width modulation signal.

[0012] In this application, the pixel driving circuit includes a voltage writing circuit, a voltage holding circuit, a voltage compensation circuit, and a light-emitting circuit. Since the input terminal of the voltage writing circuit is connected to a pulse amplitude modulation signal, the input terminal of the voltage holding circuit is connected to the output terminal of the voltage writing circuit, and the input terminal of the voltage compensation circuit is connected to the output terminal of the voltage holding circuit, the voltage information of the pulse amplitude modulation signal can be transmitted to the voltage compensation circuit. The voltage compensation circuit can then drive the light-emitting device in the light-emitting circuit based on the voltage information of the pulse amplitude modulation signal, achieving light emission control of the light-emitting device based on the pulse amplitude modulation signal. Furthermore, since the input terminal of the light-emitting circuit is connected to a pulse width modulation signal, light emission control of the light-emitting device can be achieved based on the pulse width modulation signal. Therefore, this application achieves mixed dimming of the display brightness of the light-emitting device based on both pulse amplitude modulation and pulse width modulation signals. This results in more precise control of the display brightness of the light-emitting device, thus improving the uniformity of the display brightness.

[0013] In one embodiment, the voltage compensation circuit further includes a first driving transistor, a first switching unit, and a second switching unit;

[0014] The control terminal of the first driving transistor is connected to the output terminal of the voltage holding circuit, and both the input and output terminals of the first driving transistor are connected to the light-emitting circuit.

[0015] The first terminal of the first switching unit is connected to the reference voltage gate line, the second terminal of the first switching unit is connected to the control terminal of the first driving transistor, and the third terminal of the first switching unit is connected to the input terminal of the first driving transistor.

[0016] The second switching unit is connected in parallel with the light-emitting device at the output terminal of the first driving transistor.

[0017] In this application, the voltage compensation circuit further includes a first driving transistor, a first switching unit, and a second switching unit. The control terminal of the first driving transistor is connected to the output terminal of the voltage holding circuit, and both the input and output terminals of the first driving transistor are connected to the light-emitting circuit. Since the first terminal of the first switching unit is connected to the reference voltage gate line, the second terminal of the first switching unit is connected to the control terminal of the first driving transistor, and the third terminal of the first switching unit is connected to the input terminal of the first driving transistor, this lays the foundation for writing the reference voltage signal to the control terminal of the first driving transistor and using the reference voltage signal for threshold voltage compensation. Since the second switching unit is connected in parallel with the light-emitting device to the output terminal of the first driving transistor, the light-emitting device can be short-circuited through the second switching unit during threshold voltage compensation, thus laying the foundation for controlling the light-emitting device not to emit light during threshold voltage compensation.

[0018] In one embodiment, under the control of a first enable control signal, the first switching unit turns on the reference voltage gate line and the control terminal of the first driving transistor, and the reference voltage signal output by the reference voltage gate line is written into the control terminal of the first driving transistor.

[0019] Under the control of the first light emission control signal, the first switching unit turns on the control terminal and input terminal of the first driving transistor, and the second switching unit turns on synchronously. The first driving transistor uses the reference voltage signal to perform threshold voltage compensation. The light emission device does not emit light when the first driving transistor performs threshold voltage compensation.

[0020] In this embodiment, the voltage compensation circuit includes a first switching unit and a second switching unit. The first switching unit is controlled by a first enable control signal and a first light emission control signal. The first driving transistor can use a reference voltage signal to achieve threshold voltage compensation, thus achieving threshold voltage compensation with a lower compensation voltage value. Furthermore, by controlling the second switching unit through the first light emission control signal, the light-emitting device can be controlled to not emit light during threshold voltage compensation.

[0021] In one embodiment, the first switching unit includes a second driving transistor;

[0022] The input terminal of the second driving transistor is connected to the reference voltage gate line, and the output terminal of the second driving transistor is connected to the control terminal of the first driving transistor. Under the control of the first enable control signal, the second driving transistor is turned on.

[0023] In this embodiment, the second driving transistor is turned on by the first enable control signal, which can turn on the control terminal of the first driving transistor and the reference voltage gate line, thereby enabling the reference voltage signal to be written to the control terminal of the first driving transistor.

[0024] In one embodiment, the first switching unit includes a third driving transistor, and the second switching unit includes a fourth driving transistor;

[0025] The input terminal of the third driving transistor is connected to the control terminal of the first driving transistor, and the output terminal of the third driving transistor is connected to the input terminal of the first driving transistor.

[0026] The fourth driving transistor is connected in parallel with the light-emitting device to the output terminal of the first driving transistor;

[0027] Under the control of the first light emission control signal, the third driving transistor and the fourth driving transistor are synchronously turned on.

[0028] In this embodiment, by connecting the fourth driving transistor in parallel with the light-emitting device, and by synchronously controlling the third driving transistor and the fourth driving transistor to conduct synchronously through the first light-emitting signal, it is possible to achieve threshold voltage compensation while ensuring that the light-emitting device does not emit light during threshold voltage compensation.

[0029] In one embodiment, the second input terminal of the voltage writing circuit is connected to the reference voltage gate line;

[0030] The voltage writing circuit is configured to write the pulse amplitude modulation signal and the reference voltage signal into the voltage holding circuit;

[0031] The voltage compensation circuit is configured to write the reference voltage signal into the control terminal of the first driving transistor and use the reference voltage signal to perform threshold voltage compensation, wherein the voltage signal at the control terminal of the first driving transistor is changed from the reference voltage signal to the first voltage signal.

[0032] The voltage holding circuit is configured to adjust the control terminal voltage signal of the first driving transistor from the first voltage signal to the second voltage signal according to the signal change between the written pulse amplitude modulation signal and the reference voltage signal.

[0033] When the voltage signal at the control terminal of the first driving transistor is the second voltage signal, the light-emitting device emits light under the drive of the first driving transistor and under the control of the pulse width modulation signal.

[0034] In this embodiment, the voltage compensation circuit writes a reference voltage signal to the control terminal of the first driving transistor, allowing the first driving transistor to perform threshold voltage compensation using the reference voltage signal. This causes the control terminal voltage signal of the first driving transistor to change from the reference voltage signal to the first voltage signal. Since the voltage writing circuit writes the pulse amplitude modulation signal and the reference voltage signal to the voltage holding circuit, and the output of the voltage holding circuit is connected to the control terminal of the first driving transistor, the voltage holding circuit adjusts the control terminal voltage signal of the first driving transistor from the first voltage signal to the second voltage signal based on the signal change between the written pulse amplitude modulation signal and the reference voltage signal. This second voltage signal is then only related to the first driving transistor. The threshold voltage, reference voltage signal, and pulse amplitude modulation signal of the body transistor are related. Therefore, when the control terminal voltage signal of the first driving transistor is the second voltage signal, the light-emitting device will emit light under the drive of the first driving transistor and under the control of the pulse width modulation signal. The luminous current of the light-emitting device is related to the threshold voltage, reference voltage signal, pulse amplitude modulation signal, and pulse width modulation signal of the first driving transistor. Since the threshold voltage and reference voltage signal are fixed, the display brightness of the light-emitting device can be mixed and dimmed based on the pulse amplitude modulation signal and the pulse width modulation signal. This makes the control of the display brightness of the light-emitting device more precise, thus improving the uniformity of the display brightness of the light-emitting device.

[0035] In one embodiment, the light-emitting circuit further includes a fifth driving transistor;

[0036] The fifth driving transistor is connected between the power supply voltage output terminal and the input terminal of the first driving transistor. The fifth driving transistor is configured to be turned on under the control of the second light emission control signal. The light emission device emits light after the fifth driving transistor is turned on.

[0037] Specifically, when the voltage compensation circuit performs threshold voltage compensation and the light-emitting device emits light, the levels of the first light-emitting control signal and the second light-emitting control signal are opposite.

[0038] In this embodiment, by setting the levels of the first light emission control signal and the second light emission control signal to be opposite during the threshold voltage compensation stage and the light emission stage, control over the threshold voltage compensation and the light emission of the light-emitting device can be achieved, and the light-emitting device does not emit light during the threshold voltage compensation stage.

[0039] In one embodiment, when the voltage compensation circuit performs threshold voltage compensation, the first light emission control signal is a high-level signal and the second light emission control signal is a low-level signal; when the light-emitting device emits light, the first light emission control signal is a low-level signal and the second light emission control signal is a low-level signal.

[0040] In this embodiment, by setting the high and low level outputs of the first light-emitting control signal and the second light-emitting control signal, the control process of threshold voltage compensation and light emission of the light-emitting device can be realized, and the light-emitting device does not emit light during threshold voltage compensation.

[0041] Secondly, this application also provides a pixel driving circuit, the pixel driving circuit comprising:

[0042] A voltage writing circuit, wherein the input terminal of the voltage writing circuit is connected to a pulse amplitude modulation signal, and the control terminal is connected to a first enable control signal;

[0043] A voltage holding circuit, wherein the input terminal of the voltage holding circuit is connected to the output terminal of the voltage writing circuit, and the control terminal is connected to a second enable control signal;

[0044] A voltage compensation circuit is provided, wherein the input terminal of the voltage compensation circuit is connected to the output terminal of the voltage holding circuit, and the voltage compensation circuit is configured to drive the light-emitting device in the light-emitting circuit; the first control terminal of the voltage compensation circuit is connected to a first enable control signal, and the second control terminal is connected to a first light-emitting control signal.

[0045] A light-emitting circuit, wherein the control terminal of the light-emitting circuit is connected to a second light-emitting control signal, and the input terminal of the light-emitting circuit is connected to a pulse width modulation signal, and the light-emitting device in the light-emitting circuit emits light under the drive of the voltage compensation circuit and under the control of the pulse width modulation signal;

[0046] In the first stage, the first enable control signal is a high-level signal. Under the action of the first enable control signal, the voltage writing circuit is turned on, and the voltage compensation circuit writes the reference voltage.

[0047] In the second stage, the first light emission control signal is a high-level signal. Under the action of the first light emission control signal, the voltage compensation circuit uses the reference voltage to perform threshold voltage compensation.

[0048] In the third stage, the second enable control signal is a high-level signal, and the voltage holding circuit is turned on under the action of the second enable control signal;

[0049] In the fourth stage, the second light-emitting control signal is a high-level signal, and the light-emitting circuit is turned on under the action of the second light-emitting control signal.

[0050] In this application, the pixel driving circuit includes a voltage writing circuit, a voltage holding circuit, a voltage compensation circuit, and a light-emitting circuit. The voltage writing circuit's input terminal receives a pulse amplitude modulation signal, and its control terminal receives a first enable control signal. The voltage holding circuit's input terminal is connected to the voltage writing circuit's output terminal, and its control terminal receives a second enable control signal. The voltage compensation circuit's input terminal is connected to the voltage holding circuit's output terminal, its first control terminal receives a first enable control signal, and its second control terminal receives a first light-emitting control signal. Thus, in the first stage, because the first enable control signal is high-level, the voltage writing circuit is turned on, receiving the pulse amplitude modulation signal, while the voltage compensation circuit writes a reference voltage. In the second stage, because the first light-emitting control signal is high-level, the voltage compensation circuit uses the reference voltage for threshold voltage compensation, laying the foundation for driving the light-emitting device in the light-emitting circuit. In the third stage, because the second enable control signal... When the signal is high, the voltage holding circuit is turned on under the action of the second enable control signal. This allows the voltage holding circuit to transmit the voltage information of the pulse amplitude modulation signal input to the voltage writing circuit to the voltage compensation circuit. Since the voltage compensation circuit is configured to drive the light-emitting device in the light-emitting circuit, the second light-emitting control signal is high in the fourth stage. Under the action of the second light-emitting control signal, after the light-emitting circuit is turned on, the voltage compensation circuit can drive the light-emitting device in the light-emitting circuit according to the voltage information of the pulse amplitude modulation signal, thus achieving light-emitting control of the light-emitting device based on the pulse amplitude modulation signal. Furthermore, since the input terminal of the light-emitting circuit is connected to a pulse width modulation signal, light-emitting control of the light-emitting device based on the pulse width modulation signal can also be achieved. Based on this, this application realizes mixed dimming of the display brightness of the light-emitting device based on both pulse amplitude modulation and pulse width modulation signals. This results in more precise control of the display brightness of the light-emitting device, thereby improving the uniformity of the display brightness.

[0051] In one embodiment, the voltage compensation circuit includes a first driving transistor, a second driving transistor, a third driving transistor, and a fourth driving transistor.

[0052] The control terminal of the first driving transistor is connected to the output terminal of the voltage holding circuit, and both the input and output terminals of the first driving transistor are connected to the light-emitting circuit.

[0053] The input terminal of the second driving transistor is connected to the reference voltage gate line, the output terminal of the second driving transistor is connected to the control terminal of the first driving transistor, and the control terminal of the second driving transistor is connected to the first enable control signal.

[0054] The input terminal of the third driving transistor is connected to the control terminal of the first driving transistor, the output terminal of the third driving transistor is connected to the input terminal of the first driving transistor, and the control terminal of the third driving transistor is connected to the first light emission control signal.

[0055] The fourth driving transistor is connected in parallel with the light-emitting device to the output terminal of the first driving transistor, and the control terminal of the fourth driving transistor is connected to the first light-emitting control signal.

[0056] In the first stage, the second driving transistor is turned on under the action of the first enable control signal; in the second stage, the third driving transistor and the fourth driving transistor are turned on under the action of the first light emission control signal.

[0057] In this application, the voltage compensation circuit includes a first driving transistor, a second driving transistor, and a third driving transistor. The control terminal of the first driving transistor is connected to the output terminal of the voltage holding circuit, and both its input and output terminals are connected to the light-emitting circuit, thus enabling the first driving transistor to drive the light-emitting device in the light-emitting circuit. The input terminal of the second driving transistor is connected to the reference voltage gate line, and its output terminal is connected to the control terminal of the first driving transistor, which is connected to a first enable control signal. The input terminal of the third driving transistor is connected to the control terminal of the first driving transistor, and its output terminal is connected to the input terminal of the first driving transistor, which is connected to a first enable control signal. The first light-emitting control signal enables the second driving transistor to conduct in the first stage, allowing the reference voltage to be written to the control terminal of the first driving transistor. The control terminal of the fourth driving transistor is connected to the first light-emitting control signal. Under the action of the first light-emitting control signal, the third and fourth driving transistors conduct in the second stage. This allows the first driving transistor to perform threshold voltage compensation using the reference voltage. Furthermore, since the fourth driving transistor is connected in parallel with the light-emitting device at the output terminal of the first driving transistor, it short-circuits the light-emitting device when the first driving transistor performs threshold voltage compensation, preventing the light-emitting device from emitting light during this process.

[0058] Thirdly, this application also provides a control method for a pixel driving circuit, applied to the above-mentioned display device, wherein the control method for the pixel driving circuit includes:

[0059] In the first stage, the voltage writing circuit writes the pulse amplitude modulation signal into the voltage holding circuit, and the voltage compensation circuit writes the reference voltage signal into the control terminal of the first driving transistor.

[0060] In the second stage, the voltage compensation circuit uses the reference voltage signal to perform threshold voltage compensation, so that the control terminal voltage signal of the first driving transistor changes to the first voltage signal;

[0061] In the third stage, the voltage writing circuit writes the reference voltage signal into the voltage holding circuit; the voltage holding circuit adjusts the control terminal voltage signal of the first driving transistor from the first voltage signal to the second voltage signal according to the signal change between the written pulse amplitude modulation signal and the reference voltage signal.

[0062] In the fourth stage, when the control terminal voltage signal of the first driving transistor is the second voltage signal, the light-emitting device in the light-emitting circuit emits light under the drive of the first driving transistor and under the control of the pulse width modulation signal.

[0063] In the aforementioned pixel driving circuit control method, based on the pixel driving circuit, the process first enters a first stage where the voltage writing circuit writes the pulse amplitude modulation signal into the voltage holding circuit, and the voltage compensation circuit writes the reference voltage signal into the control terminal of the first driving transistor. Then, in the second stage, the voltage compensation circuit uses the reference voltage signal to perform threshold voltage compensation, causing the voltage signal at the control terminal of the first driving transistor to change to the first voltage signal. Next, in the third stage, the voltage writing circuit writes the reference voltage signal into the voltage holding circuit. Thus, the voltage writing circuit writes both the pulse amplitude modulation signal and the reference voltage signal into the voltage holding circuit. Since the output terminal of the voltage holding circuit is connected to the control terminal of the first driving transistor, the voltage holding circuit adjusts the first driving transistor based on the signal change between the written pulse amplitude modulation signal and the reference voltage signal. The control terminal voltage signal is adjusted from the first voltage signal to the second voltage signal. This second voltage signal is related to the threshold voltage, reference voltage signal, and pulse amplitude modulation signal of the first driving transistor. Therefore, when the control terminal voltage signal of the first driving transistor is the second voltage signal, the light-emitting device emits light in the fourth stage under the drive of the first driving transistor and the control of the pulse width modulation signal. At this time, the light-emitting current of the light-emitting device is related to the threshold voltage, reference voltage signal, pulse amplitude modulation signal, and pulse width modulation signal of the first driving transistor. Since the threshold voltage and reference voltage signal are fixed, the display brightness of the light-emitting device is mixed and dimmed based on the pulse amplitude modulation signal and the pulse width modulation signal. This makes the control of the display brightness of the light-emitting device more precise, thus improving the uniformity of the display brightness of the light-emitting device. Attached Figure Description

[0064] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0065] Figure 1 This is a structural diagram of a pixel driving circuit according to an embodiment of this application;

[0066] Figure 2 This is a structural diagram of the pixel driving circuit when the voltage compensation circuit includes a first switching unit and a second switching unit in one embodiment of this application;

[0067] Figure 3 This is a structural diagram of a pixel driving circuit when the voltage compensation circuit includes a second driving transistor, a third driving transistor, and a fourth driving transistor in one embodiment of this application.

[0068] Figure 4 This is a structural diagram of a pixel driving circuit in one embodiment of the present application, where the voltage compensation circuit includes a second driving transistor, a third driving transistor, and a fourth driving transistor, and the light-emitting circuit includes a fifth driving transistor.

[0069] Figure 5 This is a hardware structure diagram of a pixel driving circuit in one embodiment of this application;

[0070] Figure 6 This is a hardware structure diagram of the pixel driving circuit in the first stage according to an embodiment of this application;

[0071] Figure 7 This is a hardware structure diagram of the pixel driving circuit in the second stage in one embodiment of this application;

[0072] Figure 8 This is a hardware structure diagram of the pixel driving circuit in the third stage in one embodiment of this application;

[0073] Figure 9 This is a hardware structure diagram of the pixel driving circuit in the fourth stage in one embodiment of this application;

[0074] Figure 10 This is a waveform comparison diagram of the first enable control signal, the second enable control signal, the first light emission control signal, the second light emission control signal, and the pulse amplitude modulation signal in one embodiment of this application;

[0075] Figure 11 This is a flowchart illustrating the control method of a pixel driving circuit in one embodiment of this application. Detailed Implementation

[0076] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0077] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0078] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0079] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0080] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0081] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0082] This embodiment provides a display device, which includes a pixel driving circuit, as shown below. Figure 1The pixel driving circuit includes a voltage writing circuit 100, a voltage holding circuit 200, a voltage compensation circuit 300, and a light-emitting circuit 400. The input terminal of the voltage writing circuit 100 is connected to a pulse amplitude modulation signal (PAMD). For example, the input terminal of the voltage writing circuit 100 can be connected to a PAMD data line to enable the PAMD signal input. The output terminal of the voltage writing circuit 100 is connected to the input terminal of the voltage holding circuit 200, and the voltage writing circuit 100 is also connected to a reference voltage gate line Vref. The output terminal of the voltage holding circuit 200 is connected to the input terminal of the voltage compensation circuit 300. The input terminal of the voltage compensation circuit 300 is connected to the reference voltage gate line Vref. The first and second output terminals of the voltage compensation circuit 300 are both connected to the light-emitting circuit 400. The first input terminal of the light-emitting circuit 400 is connected to the power supply voltage terminal VDD. The second input terminal of the light-emitting circuit 400 is connected to the pulse width modulation signal PWMD. For example, the second input terminal of the light-emitting circuit 400 can be connected to the PWMD data line to realize the access of the pulse width modulation signal PWMD. The output terminal of the light-emitting circuit 400 is connected to the power supply voltage terminal VSS and operates under the voltage difference between the power supply voltage terminals VDD and VSS.

[0083] It should be noted that the voltage compensation circuit 300 may also include a first driving transistor T1. The control terminal of the first driving transistor T1 is connected to the output terminal of the voltage holding circuit 200. Both the input and output terminals of the first driving transistor T1 are connected to the light-emitting circuit 400. The first driving transistor T1 can drive the light-emitting device LED in the light-emitting circuit to emit light.

[0084] The operation of the pixel driving circuit described above is mainly divided into four stages, namely the first stage, the second stage, the third stage, and the fourth stage. The first stage can be the charging stage, the second stage can be the threshold voltage compensation stage, the third stage can be the signal input stage, and the fourth stage can be the light emission stage. The operation of the pixel driving circuit described above is described below based on these four stages.

[0085] During the charging phase, the voltage writing circuit 100 writes the pulse amplitude modulation signal PAMD into the voltage holding circuit 200, while the voltage compensation circuit 300 also writes the reference voltage signal Vref into the control terminal of the first driving transistor T1.

[0086] During the threshold voltage compensation stage, the control terminal of the first driving transistor T1 is connected to the input terminal of the first driving transistor T1, forming a diode connection. At this time, the first driving transistor T1 uses the reference voltage signal Vref to perform threshold voltage compensation until the voltage difference between the control terminal and the input terminal of the first driving transistor T1 reaches the threshold voltage Vth of the control terminal. The threshold voltage compensation stage ends at this time, and the control terminal voltage signal on the control terminal of the first driving transistor T1 changes to the first voltage signal VSS+Vth.

[0087] During the signal input phase, the voltage writing circuit 100 writes the reference voltage signal Vref into the voltage holding circuit 200. The voltage signal at the input of the voltage holding circuit 200 is changed by the pulse amplitude modulation signal PAMD to the reference voltage signal Vref. The signal change at the input of the voltage holding circuit 200 is Vref - PAMD, where PAMD is the pulse amplitude modulation signal voltage. The voltage holding circuit 200 transmits this signal change Vref - PAMD to the output of the voltage holding circuit 200. Since the output of the voltage holding circuit 200 is connected to the control terminal of the first driving transistor T1, the voltage signal at the control terminal of the first driving transistor T1 changes from the first voltage signal VSS + Vth to the second voltage signal VSS + Vth + Vref - PAMD, and the signal input phase ends.

[0088] During the light-emitting stage, when the voltage signal at the control terminal of the first driving transistor T1 is the second voltage signal VSS+Vth+Vref-PAMD, the light-emitting device LED emits light under the drive of the first driving transistor T1 and under the control of the pulse width modulation signal PWND.

[0089] Thus, the luminous current I of the aforementioned LED can be calculated based on the following process:

[0090]

[0091]

[0092]

[0093] in, The luminous current of the LED light-emitting device. The mobility of the first driving transistor T1 is determined by the semiconductor material of the first driving transistor T1. The aspect ratio of the channel of the first driving transistor T1 is given. The capacitance per unit area of ​​the first driving transistor T1, This is the control terminal voltage of the first driving transistor T1. This is the output voltage of the first driving transistor T1. Since the light-emitting device LED is connected between the power supply voltage terminal VSS and the output terminal of the first driving transistor T1, therefore... , This is the operating voltage of the LED, which can be the rated voltage value. PAMD is the voltage of the pulse amplitude modulation signal.

[0094] Based on this, it can be seen that the magnitude of the luminous current of the light-emitting device LED is related to PAMD. Furthermore, since the light-emitting device is also controlled by the pulse width modulation signal PWMD, the luminous time of the light-emitting device LED can be controlled by adjusting the duty cycle of the pulse width modulation signal PWMD. In this way, the luminous brightness displayed by the light-emitting device LED will be jointly controlled by the pulse amplitude modulation signal PAMD and the pulse width modulation signal PWMD, realizing hybrid dimming based on PAMD and PWMD.

[0095] In the above embodiments, hybrid dimming of the display brightness of the LED device is achieved based on the pulse amplitude modulation signal PAMD and the pulse width modulation signal PWMD. This makes the control of the display brightness of the LED device more precise, thus improving the uniformity of the display brightness of the LED device.

[0096] In some embodiments, such as Figure 2 As shown, the voltage compensation circuit 300 includes a first switching unit 301, a second switching unit 302 and a first driving transistor T1, and the light-emitting circuit 400 includes a light-emitting device LED and a control unit 401, wherein the control unit 401 is configured to control the light-emitting device LED to emit light using a pulse width modulation signal PWMD.

[0097] In this configuration, one end of the first switching unit 301 is connected to the reference voltage gate line Vref, the second end of the first switching unit 301 is connected to the control terminal G of the first driving transistor T1, and the third end of the first switching unit 301 is connected to the input terminal D of the first driving transistor T1.

[0098] After the first enable control signal is input to the first switching unit 301, the first switching unit 301 can turn on the reference voltage gate line Vref and the control terminal G of the first driving transistor T1, so that the reference voltage signal Vref can be written into the control terminal G of the first driving transistor T1.

[0099] After the first light-emitting control signal is input to the first switching unit 301, the first switching unit 301 will turn on the control terminal G and the input terminal D of the first driving transistor T1. At this time, the first driving transistor T1 forms a diode connection, so that the first driving transistor T1 uses the reference voltage Vref to perform threshold voltage compensation, that is, the control terminal G discharges towards the output terminal S until the voltage difference between the control terminal G and the output terminal S is equal to the threshold voltage Vth of the first driving transistor T1, and the threshold voltage compensation ends.

[0100] It should be noted that in this embodiment, the first switching unit 301 and the second switching unit 302 will be simultaneously connected to the first light-emitting control signal. After receiving the first light-emitting control signal, the second switching unit 302 will be turned on. At this time, during the threshold voltage compensation stage, the current will flow through the second switching unit 302 to the power supply voltage terminal VSS. No current flows through the light-emitting device LED. Therefore, the light-emitting device LED does not emit light when the first driving transistor T1 performs threshold voltage compensation. This can avoid the situation where the light-emitting device LED is overexposed during the threshold voltage compensation stage in the pixel driving circuit. Therefore, it can improve the uniformity of the display brightness of the light-emitting device LED.

[0101] In some embodiments, such as Figure 3 As shown, the first switching unit 301 includes a second driving transistor T2 and a third driving transistor T3, and the second switching unit 302 includes a fourth driving transistor T4.

[0102] In this configuration, the input terminal of the second driving transistor T2 is connected to the reference voltage gate line Vref, and the output terminal of the second driving transistor T2 is connected to the control terminal G of the first driving transistor T1. The control terminal of the second driving transistor T2 is connected to the first control gate line Gn-1, and the first control gate line Gn-1 is configured to output a first enable control signal Gn-1. Under the control of the first enable control signal Gn-1, the second driving transistor T2 will be turned on, making the path between the reference voltage gate line and the control terminal G of the first driving transistor T1 open. In this way, the reference voltage signal Vref can be written to the control terminal G of the first driving transistor T1.

[0103] The input terminal of the third driving transistor T3 is connected to the control terminal G of the first driving transistor T1, and the output terminal of the third driving transistor T3 is connected to the output terminal D of the first driving transistor T1. The control terminal of the third driving transistor T3 is connected to the first light-emitting control signal EM1. The input terminal of the fourth driving transistor T4 is connected to the output terminal S of the first driving transistor T1, and the output terminal of the fourth driving transistor T4 is connected to the power supply voltage terminal VSS. The control terminal of the fourth driving transistor T4 is connected to the output terminal of the first light-emitting control signal EM1. The fourth driving transistor T4 is connected in parallel with the light-emitting device LED.

[0104] Under the control of the first light-emitting control signal EM1, the third driving transistor T3 and the fourth driving transistor T4 will be turned on synchronously, so that the path between the control terminal G, input terminal D, output terminal S, and power supply voltage terminal VSS of the first driving transistor T1 will be connected. The control terminal G of the first driving transistor T1 will discharge to the output terminal S, that is, perform threshold voltage compensation, until the voltage difference between the control terminal G and the output terminal S of the first driving transistor T1 reaches the threshold voltage Vth of the first driving transistor T1. Since the fourth driving transistor T4 is connected in parallel with the light-emitting device LED, there will be no current in the branch where the light-emitting device LED is located during the threshold voltage compensation stage. The light-emitting device LED does not emit light during the threshold voltage compensation stage, which helps to improve the uniformity of the display brightness of the light-emitting device LED in the pixel driving circuit.

[0105] In some embodiments, refer to Figure 4 The light-emitting circuit 400 includes a fifth driving transistor T5. The input terminal of the fifth driving transistor T5 is connected to the power supply voltage terminal VDD, the output terminal of the fifth driving transistor T5 is connected to the input terminal D of the first driving transistor T1, and the control terminal of the fifth driving transistor T5 is connected to the second light-emitting control signal EM2.

[0106] Under the control of the second light-emitting control signal EM2, the fifth driving transistor T5 will be turned on, thereby turning on the path of the light-emitting device LED, and the light-emitting device LED will emit light.

[0107] It should be noted that during the threshold voltage compensation stage and the light emission stage, the levels of the first light emission control signal EM1 and the second light emission control signal EM2 are opposite.

[0108] As an example, during the threshold voltage compensation stage, the first light emission control signal EM1 is a high-level signal and the second light emission control signal EM2 is a low-level signal; during the light emission stage, the first light emission control signal EM1 is a low-level signal and the second light emission control signal EM2 is a low-level signal.

[0109] In this embodiment, the first light-emitting control signal EM1 can synchronously turn on the third driving transistor T3 and the fourth driving transistor T4, thereby realizing threshold voltage compensation and controlling the light-emitting device LED not to emit light during the threshold voltage compensation stage. Therefore, the first light-emitting control signal EM1 serves as the start signal for threshold voltage compensation and controls the light-emitting device LED not to emit light during the threshold voltage compensation stage. The second light-emitting control signal EM2 serves as the switching signal for controlling the light-emitting device LED to emit light.

[0110] In some embodiments, Figure 5 The circuit structure diagram of the pixel driving circuit in this embodiment is shown. Figure 5As can be seen, the input terminal of the voltage writing circuit 100 is connected to the pulse amplitude modulation signal PAMD, and the control terminal is connected to the first enable control signal Gn-1; the input terminal of the voltage holding circuit 200 is connected to the output terminal of the voltage writing circuit 100, and the control terminal is connected to the second enable control signal Gn; the input terminal of the voltage compensation circuit 300 is connected to the output terminal of the voltage holding circuit 200, and the voltage compensation circuit 300 is configured to drive the light-emitting device LED in the light-emitting circuit 400; the first control terminal of the voltage compensation circuit 300 is connected to the first enable control signal Gn-1, and the second control terminal is connected to the first light-emitting control signal EM1; the control terminal of the light-emitting circuit 400 is connected to the second light-emitting control signal EM2, and the input terminal of the light-emitting circuit 400 is connected to the pulse width modulation signal PWMD. The light-emitting device LED in the light-emitting circuit 400 emits light under the drive of the voltage compensation circuit 300 and under the control of the pulse width modulation signal PWMD.

[0111] As an example, in the first stage, the first enable control signal Gn-1 is a high-level signal. Under the action of the first enable control signal Gn-1, the voltage writing circuit 100 is turned on, the voltage writing circuit 100 is connected to the pulse amplitude modulation signal PAMD, and the voltage compensation circuit 300 writes the reference voltage Vref. In the second stage, the first light emission control signal EM1 is a high-level signal. Under the action of the first light emission control signal EM1, the voltage compensation circuit 300 uses the reference voltage Vref to perform threshold voltage compensation. In the third stage, the second enable control signal Gn is a high-level signal. Under the action of the second enable control signal Gn, the voltage holding circuit 2... When the voltage holding circuit 200 is turned on, it can transmit the voltage information of the pulse amplitude modulation signal PAMD to the voltage compensation circuit 300, laying the foundation for the voltage compensation circuit 300 to drive the light-emitting device LED in the light-emitting circuit 400. In the fourth stage, the second light-emitting control signal EM2 is a high-level signal. Under the action of the second light-emitting control signal EM2, the light-emitting circuit 400 is turned on, and the light-emitting device LED emits light under the drive of the voltage compensation circuit 300 and the control of the pulse width modulation signal PWMD. Therefore, the mixed dimming of the light-emitting device LED based on the pulse amplitude modulation signal PAMD and the pulse width modulation signal PWMD is realized.

[0112] The following is combined Figure 5 The specific circuit structure of the pixel driving circuit in this embodiment will be described in detail.

[0113] In this embodiment, the pixel driving circuit consists of a voltage writing circuit 100, a voltage holding circuit 200, a voltage compensation circuit 300, and a light-emitting circuit 400.

[0114] The voltage writing circuit 100 includes a sixth driving transistor T6 and a seventh driving transistor T7. The input terminal of the sixth driving transistor T6 is connected to the PAMD data line, and the output terminal of the sixth driving transistor T6 is connected to the input terminal C of the voltage holding circuit 200. The control terminal of the sixth driving transistor T6 is connected to the first control gate line Gn-1. The input terminal of the seventh driving transistor T7 is connected to the reference voltage gate line Vref, and the output terminal of the seventh driving transistor T7 is connected to the input terminal C of the voltage holding circuit 200. The control terminal of the seventh driving transistor T7 is connected to the second control gate line Gn. The first control gate line is configured to output a first enable control signal Gn-1, and the second control gate line is configured to output a second enable control signal Gn.

[0115] The voltage holding circuit 200 includes a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is connected to the input terminal C of the voltage holding circuit, and the second end of the first capacitor C1 is connected to the control terminal G of the first driving transistor T1. The first end of the second capacitor C2 is connected between point C and the first end of the first capacitor C1, and the second end of the second capacitor C2 is connected to the power supply voltage terminal VDD.

[0116] The voltage compensation circuit 300 includes a first driving transistor T1, a second driving transistor T2, a third driving transistor T3, and a fourth driving transistor T4. The control terminal G of the first driving transistor T1 is connected to the output terminal of the voltage holding circuit. The input terminal D of the first driving transistor T1 is connected to the output terminal of the fifth driving transistor T5. The output terminal S of the first driving transistor T1 is connected to the light-emitting device LED and the input terminal of the fourth driving transistor T4. The input terminal of the second driving transistor T2 is connected to the reference voltage gate line Vref. The output terminal of the second driving transistor T2 is connected to the control terminal G of the first driving transistor T1. The control terminal of transistor T2 is connected to the first control gate line Gn-1; the input terminal of the third driving transistor T3 is connected to the control terminal G of the first driving transistor T1, the output terminal of the third driving transistor T3 is connected to the output terminal D of the first driving transistor T1, and the control terminal of the third driving transistor T3 is connected to the first light-emitting control signal EM1; the input terminal of the fourth driving transistor T4 is connected to the output terminal S of the first driving transistor T1, the output terminal of the fourth driving transistor T4 is connected to the power supply voltage terminal VSS, the control terminal of the fourth driving transistor T4 is connected to the first light-emitting control signal EM1, and the fourth driving transistor T4 is connected in parallel with the light-emitting device LED.

[0117] The light-emitting circuit 400 includes a fifth driving transistor T5, a light-emitting device LED, and a control unit 401. The control unit 401 can be an eighth driving transistor T8. The input terminal of the fifth driving transistor T5 is connected to the power supply voltage terminal VDD, and the output terminal of the fifth driving transistor T5 is connected to the input terminal D of the first driving transistor T1. The control terminal of the fifth driving transistor T5 is connected to the second light-emitting control signal EM2. The light-emitting device LED is connected in parallel with the fourth driving transistor T4, and the input terminal of the light-emitting device LED is connected to the output terminal S of the first driving transistor T1. The output terminal of the light-emitting device LED is connected to the power supply voltage terminal VSS. The input terminal of the eighth driving transistor T8 is connected to the PWMD data line. The eighth driving transistor T8 is connected in the parallel branch of the light-emitting device LED and the fourth driving transistor T4, and the output terminal of the eighth driving transistor is connected to the input terminal of the light-emitting device LED. The control terminal and input terminal of the eighth driving transistor T8 are connected to the control terminal of the ninth driving transistor T9. The ninth driving transistor T9 is in the parallel branch of the light-emitting device LED and is connected in series with the light-emitting device LED.

[0118] Based on the circuit structure of the pixel driving circuit described above, the control process of the pixel driving circuit in this embodiment is as follows: the first stage (charging stage), the second stage (threshold voltage compensation stage), the third stage (signal input stage), and the fourth stage (light emission stage). The control process of the pixel driving circuit in this embodiment will be described in detail below based on these four stages and the circuit structure of the pixel driving circuit described above.

[0119] During the charging phase, refer to Figure 6 ( Figure 6 (A cross indicates that the driving transistor is not turned on). The first control gate line Gn-1 outputs a high-level signal, while the second control gate line Gn, the first light-emitting control signal EM1, and the second light-emitting control signal EM2 all output low-level signals. At this time, only the control terminal of the second driving transistor T2 and the sixth driving transistor T6 are turned on. Thus, the pulse amplitude modulation signal PAMD is written to point C, and the reference voltage signal Vref is written to the control terminal G of the first driving transistor T1, until the voltage at point C changes to PAMD and the voltage at point G changes to the reference voltage Vref, at which point the charging phase ends.

[0120] During the threshold voltage compensation stage, refer to Figure 7 ( Figure 7(A cross indicates the driving transistor is not turned on). The first light-emitting control signal EM1 outputs a high-level signal, and the first control gate line Gn-1, the second control gate line Gn, and the second light-emitting control signal EM2 all output low-level signals. At this time, the control terminal of the third driving transistor T3 and the fourth driving transistor T4 are turned on. Since the voltage difference between the control terminal G and the output terminal S of the first driving transistor T1 is Vref, and Vref is greater than the threshold voltage Vth of the first driving transistor T1, the first driving transistor T1 will also be turned on. A path is formed between the control terminal G, the input terminal D, the output terminal S, and the power supply voltage terminal VSS of the first driving transistor T1. The control terminal G of the first driving transistor T1 discharges to the output terminal S until the voltage difference between the control terminal G and the output terminal S is equal to Vth. The control terminal G of the first driving transistor T1 stops discharging to the output terminal S, and the threshold voltage compensation stage ends. At this time, the voltage at the control terminal G of the first driving transistor T1 is VSS+Vth.

[0121] During the signal input phase, refer to Figure 8 ( Figure 8 (A cross indicates the driving transistor is not turned on). The second control line Gn outputs a high-level signal, while the first control gate line Gn-1, the second control line Gn, the first light-emitting control signal EM1, and the second light-emitting control signal EM2 all output low-level signals. At this time, the seventh driving transistor T7 is turned on. Since the reference voltage Vref is greater than PAMD, the voltage change at point C is Vref-PAMD. However, since the first capacitor C1 and the second capacitor C2 are already in a stable state during the charging phase, the voltage changes at points C and G will be consistent. Therefore, the voltage at point G will change from Vref-PAMD to VSS+Vth+Vref-PAMD. At this time, the voltage at point G is greater than the threshold voltage Vth of the first driving transistor T1, so the first driving transistor T1 is turned on, and the signal input phase ends.

[0122] During the luminescence stage, reference Figure 9 ( Figure 9 (A cross indicates the driving transistor is not turned on) The second light-emitting control signal EM2 outputs a high-level signal, and the first control gate line Gn-1, the second control gate line Gn, the first light-emitting control signal EM1, and the second control gate line Gn all output low-level signals. The PAMD data line begins to output the pulse width modulation signal PAMD. At this time, the fifth driving transistor T5 turns on, the path of the light-emitting device LED is turned on, and the light-emitting device LED begins to emit light. The luminous current of the light-emitting device LED is calculated as follows:

[0123]

[0124]

[0125]

[0126] in, The luminous current of the LED light-emitting device. The mobility of the first driving transistor T1 is determined by the semiconductor material of the first driving transistor T1. The aspect ratio of the channel of the first driving transistor T1 is given. The capacitance per unit area of ​​the first driving transistor T1, This is the control terminal voltage of the first driving transistor T1. This is the output voltage of the first driving transistor T1. Since the light-emitting device LED is connected between the power supply voltage terminal VSS and the output terminal of the first driving transistor T1, therefore... , The operating voltage of the LED is the rated voltage, and PAMD is the voltage of the pulse amplitude modulation signal. Based on this, it can be seen that the luminous current of the LED is controlled by PAMD, thereby controlling the display brightness of the LED based on PAMD.

[0127] Meanwhile, the eighth driving transistor T8 is continuously turned on and off under the control of the pulse width modulation signal PAMD, which controls the ninth driving transistor T9 to be turned on intermittently. Thus, the light emission time of the light-emitting device LED is controlled by the ninth driving transistor T9. Therefore, the light emission time of the light-emitting device LED can be controlled by adjusting the duty cycle of the pulse width modulation signal PAMD, thereby realizing the control of the display brightness of the light-emitting device LED in the external environment. This realizes the control of the display brightness of the light-emitting device LED based on PWMD.

[0128] Based on this, this embodiment realizes hybrid dimming of the display brightness of the LED device based on PAMD and PWMD during the light emission stage, which makes the control of the display brightness of the LED device more precise and helps to improve the uniformity of the display brightness of the LED device.

[0129] In some embodiments, refer to Figure 10 , Figure 10 The waveforms of the first enable control signal Gn-1, the second enable control signal Gn, the first light emission control signal EM1, the second light emission control signal EM2, and the pulse amplitude modulation signal PAMD are shown in this embodiment.

[0130] During the charging phase, only the first enable control signal Gn-1 is a high-level signal, which controls the second driving transistor T2 and the sixth driving transistor T6 to conduct; the second enable control signal Gn, the first light emission control signal EM1, and the second light emission control signal EM2 are all low-level signals, and the pulse amplitude modulation signal PAMD has no output; the driving transistors controlled by the second enable control signal Gn, the first light emission control signal EM1, the second light emission control signal EM2, and the pulse amplitude modulation signal PAMD are all not turned on.

[0131] During the threshold voltage compensation stage, only the first light emission control signal EM1 is a high-level signal, which controls the third driving transistor T3 and the fourth driving transistor T4 to conduct; the first enable control signal Gn-1, the second enable control signal Gn, and the second light emission control signal EM2 are all low-level signals, and the pulse amplitude modulation signal PAMD has no output; the driving transistors controlled by the second enable control signal Gn, the first enable control signal Gn-1, the second light emission control signal EM2, and the pulse amplitude modulation signal PAMD are all not turned on.

[0132] During the signal input phase, only the second enable control signal Gn is a high-level signal, which controls the seventh driving transistor T7 to conduct; the first enable control signal Gn-1, the first light emission control signal EM1, and the second light emission control signal EM2 are all low-level signals, and the pulse amplitude modulation signal PAMD has no output; the driving transistors controlled by the first enable control signal Gn-1, the first light emission control signal EM1, the second light emission control signal EM2, and the pulse amplitude modulation signal PAMD are all not turned on.

[0133] During the light-emitting stage, the second light-emitting control signal EM2 is a high-level signal, and the pulse amplitude modulation signal PAMD is output. The second light-emitting control signal EM2 controls the fifth driving transistor T5 to turn on, and the pulse amplitude modulation signal PAMD controls the eighth driving transistor T8 to continuously turn on and off, thereby controlling the ninth driving transistor T9 to turn on intermittently, realizing the light-emitting time control of the LED device. The first enable control signal Gn-1, the first light-emitting control signal EM1, and the second enable control signal Gn are all low-level signals, and the driving transistors controlled by the first enable control signal Gn-1, the first light-emitting control signal EM1, and the second enable control signal Gn are not turned on.

[0134] In this embodiment, the first light-emitting control signal EM1 simultaneously controls the third driving transistor T3 and the fourth driving transistor T4. This reduces the number of control signals and simplifies the control logic of the pixel driving circuit while achieving mixed dimming of the LED device based on PAMD and PWMD.

[0135] In addition, by controlling the third driving transistor T3 and the fourth driving transistor T4 simultaneously through the first light-emitting control signal EM1, the LED can be short-circuited during the threshold voltage compensation stage, so that no current flows through the LED during the threshold voltage compensation stage. This avoids the situation where the LED will suddenly brighten during the threshold voltage compensation stage and helps to improve the uniformity of the display brightness of the LED.

[0136] It should be noted that the first driving transistor T1, the second driving transistor T2, the third driving transistor T3, the fourth driving transistor T4, the fifth driving transistor T5, the sixth driving transistor T6, the seventh driving transistor T7, the eighth driving transistor T8, and the ninth driving transistor T8 mentioned above can all be thin-film transistors (TFTs).

[0137] As an example, the control terminal of any of the above driving transistors can be the gate, the input terminal of any of the above driving transistors can be the source, and the output terminal of any of the above driving transistors can be the drain.

[0138] It is understood that the pixel driving circuit described above can also take other forms, and is not limited to the forms already mentioned in the above embodiments, as long as it can achieve the function of pixel driving.

[0139] This embodiment also provides a control method for a pixel driving circuit, applied to the display device in the above embodiments. The control method for the pixel driving circuit includes:

[0140] Step 202: In the first stage, the voltage writing circuit writes the pulse amplitude modulation signal into the voltage holding circuit, and the voltage compensation circuit writes the reference voltage signal into the control terminal of the first driving transistor.

[0141] Step 204: In the second stage, the voltage compensation circuit uses the reference voltage signal to perform threshold voltage compensation, so that the control terminal voltage signal of the first driving transistor changes to the first voltage signal.

[0142] Step 206, in the third stage, the voltage writing circuit writes the reference voltage signal into the voltage holding circuit; the voltage holding circuit adjusts the control terminal voltage signal of the first driving transistor from the first voltage signal to the second voltage signal according to the signal change between the written pulse amplitude modulation signal and the reference voltage signal.

[0143] Step 208, in the fourth stage, when the control terminal voltage signal of the first driving transistor is the second voltage signal, the light-emitting device in the light-emitting circuit emits light under the drive of the first driving transistor and under the control of the pulse width modulation signal.

[0144] The specific implementation of the control method of the pixel driving circuit in this embodiment is consistent with the implementation of the relevant embodiments of the pixel driving circuit described above, and will not be repeated here.

[0145] It should be noted that, in the embodiments of this application, "display device" refers to any device with screen display and data processing capabilities. For example, display devices include, but are not limited to, smart TVs, mobile terminals, computers, monitors, advertising screens, wearable devices, virtual reality devices, and augmented reality devices.

[0146] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0147] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0148] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A display device, characterized in that, The display device includes a pixel driving circuit, the pixel driving circuit comprising: A voltage writing circuit, wherein the input terminal of the voltage writing circuit is connected to a pulse amplitude modulation signal; A voltage holding circuit, wherein the input terminal of the voltage holding circuit is connected to the output terminal of the voltage writing circuit; A voltage compensation circuit, wherein the input terminal of the voltage compensation circuit is connected to the output terminal of the voltage holding circuit, and the voltage compensation circuit is configured to drive the light-emitting device in the light-emitting circuit; A light-emitting circuit, wherein the input terminal of the light-emitting circuit is connected to a pulse width modulation signal, and the light-emitting device in the light-emitting circuit emits light under the drive of the voltage compensation circuit and under the control of the pulse width modulation signal.

2. The display device according to claim 1, characterized in that, The voltage compensation circuit includes a first driving transistor, a first switching unit, and a second switching unit. The control terminal of the first driving transistor is connected to the output terminal of the voltage holding circuit, and both the input and output terminals of the first driving transistor are connected to the light-emitting circuit. The first terminal of the first switching unit is connected to the reference voltage gate line, the second terminal of the first switching unit is connected to the control terminal of the first driving transistor, and the third terminal of the first switching unit is connected to the input terminal of the first driving transistor. The second switching unit is connected in parallel with the light-emitting device at the output terminal of the first driving transistor.

3. The display device according to claim 2, characterized in that, Under the control of the first enable control signal, the first switching unit turns on the control terminal of the reference voltage gate line and the first driving transistor, and the reference voltage signal output by the reference voltage gate line is written into the control terminal of the first driving transistor. Under the control of the first light emission control signal, the first switching unit turns on the control terminal and input terminal of the first driving transistor, and the second switching unit turns on synchronously. The first driving transistor uses the reference voltage signal to perform threshold voltage compensation. The light emission device does not emit light when the first driving transistor performs threshold voltage compensation.

4. The display device according to claim 2, characterized in that, The first switching unit includes a second driving transistor; The input terminal of the second driving transistor is connected to the reference voltage gate line, and the output terminal of the second driving transistor is connected to the control terminal of the first driving transistor. Under the control of the first enable control signal, the second driving transistor is turned on.

5. The display device according to claim 2, characterized in that, The first switching unit includes a third driving transistor, and the second switching unit includes a fourth driving transistor; The input terminal of the third driving transistor is connected to the control terminal of the first driving transistor, and the output terminal of the third driving transistor is connected to the input terminal of the first driving transistor. The fourth driving transistor is connected in parallel with the light-emitting device to the output terminal of the first driving transistor; Under the control of the first light emission control signal, the third driving transistor and the fourth driving transistor are synchronously turned on.

6. The display device according to claim 2, characterized in that, The second input terminal of the voltage writing circuit is connected to the reference voltage gate line; The voltage writing circuit is configured to write the pulse amplitude modulation signal and the reference voltage signal into the voltage holding circuit; The voltage compensation circuit is configured to write the reference voltage signal into the control terminal of the first driving transistor and use the reference voltage signal to perform threshold voltage compensation, wherein the voltage signal at the control terminal of the first driving transistor is changed from the reference voltage signal to the first voltage signal. The voltage holding circuit is configured to adjust the control terminal voltage signal of the first driving transistor from the first voltage signal to the second voltage signal according to the signal change between the written pulse amplitude modulation signal and the reference voltage signal. When the voltage signal at the control terminal of the first driving transistor is the second voltage signal, the light-emitting device emits light under the drive of the first driving transistor and under the control of the pulse width modulation signal.

7. The display device according to claim 5, characterized in that, The light-emitting circuit also includes a fifth driving transistor; The fifth driving transistor is connected between the power supply voltage output terminal and the input terminal of the first driving transistor. The fifth driving transistor is configured to be turned on under the control of the second light emission control signal. The light emission device emits light after the fifth driving transistor is turned on. Specifically, when the voltage compensation circuit performs threshold voltage compensation and the light-emitting device emits light, the levels of the first light-emitting control signal and the second light-emitting control signal are opposite.

8. The display device according to claim 7, characterized in that, When the voltage compensation circuit performs threshold voltage compensation, the first light emission control signal is a high-level signal and the second light emission control signal is a low-level signal; when the light emission device emits light, the first light emission control signal is a low-level signal and the second light emission control signal is a low-level signal.

9. A pixel driving circuit, characterized in that, The pixel driving circuit includes: A voltage writing circuit, wherein the input terminal of the voltage writing circuit is connected to a pulse amplitude modulation signal, and the control terminal is connected to a first enable control signal; A voltage holding circuit, wherein the input terminal of the voltage holding circuit is connected to the output terminal of the voltage writing circuit, and the control terminal is connected to a second enable control signal; A voltage compensation circuit is provided, wherein the input terminal of the voltage compensation circuit is connected to the output terminal of the voltage holding circuit, and the voltage compensation circuit is configured to drive the light-emitting device in the light-emitting circuit; the first control terminal of the voltage compensation circuit is connected to a first enable control signal, and the second control terminal is connected to a first light-emitting control signal. A light-emitting circuit, wherein the control terminal of the light-emitting circuit is connected to a second light-emitting control signal, and the input terminal of the light-emitting circuit is connected to a pulse width modulation signal, and the light-emitting device in the light-emitting circuit emits light under the drive of the voltage compensation circuit and under the control of the pulse width modulation signal; In the first stage, the first enable control signal is a high-level signal. Under the action of the first enable control signal, the voltage writing circuit is turned on, and the voltage compensation circuit writes the reference voltage. In the second stage, the first light emission control signal is a high-level signal. Under the action of the first light emission control signal, the voltage compensation circuit uses the reference voltage to perform threshold voltage compensation. In the third stage, the second enable control signal is a high-level signal, and the voltage holding circuit is turned on under the action of the second enable control signal; In the fourth stage, the second light-emitting control signal is a high-level signal, and the light-emitting circuit is turned on under the action of the second light-emitting control signal.

10. The pixel driving circuit according to claim 9, characterized in that, The voltage compensation circuit includes a first driving transistor, a second driving transistor, a third driving transistor, and a fourth driving transistor. The control terminal of the first driving transistor is connected to the output terminal of the voltage holding circuit, and both the input and output terminals of the first driving transistor are connected to the light-emitting circuit. The input terminal of the second driving transistor is connected to the reference voltage gate line, the output terminal of the second driving transistor is connected to the control terminal of the first driving transistor, and the control terminal of the second driving transistor is connected to the first enable control signal. The input terminal of the third driving transistor is connected to the control terminal of the first driving transistor, the output terminal of the third driving transistor is connected to the input terminal of the first driving transistor, and the control terminal of the third driving transistor is connected to the first light emission control signal. The fourth driving transistor is connected in parallel with the light-emitting device to the output terminal of the first driving transistor, and the control terminal of the fourth driving transistor is connected to the first light-emitting control signal. In the first stage, the second driving transistor is turned on under the action of the first enable control signal; in the second stage, the third driving transistor and the fourth driving transistor are turned on under the action of the first light emission control signal.

11. A control method for a pixel driving circuit, characterized in that, Applied to a display device as described in any one of 1-8; the method includes the following steps: In the first stage, the voltage writing circuit writes the pulse amplitude modulation signal into the voltage holding circuit, and the voltage compensation circuit writes the reference voltage signal into the control terminal of the first driving transistor. In the second stage, the voltage compensation circuit uses the reference voltage signal to perform threshold voltage compensation, so that the control terminal voltage signal of the first driving transistor changes to the first voltage signal; In the third stage, the voltage writing circuit writes the reference voltage signal into the voltage holding circuit; the voltage holding circuit adjusts the control terminal voltage signal of the first driving transistor from the first voltage signal to the second voltage signal according to the signal change between the written pulse amplitude modulation signal and the reference voltage signal. In the fourth stage, when the control terminal voltage signal of the first driving transistor is the second voltage signal, the light-emitting device in the light-emitting circuit emits light under the drive of the first driving transistor and under the control of the pulse width modulation signal.

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