CN114974110A

CN114974110A - Pixel driving circuit, control method, display screen and display device

Info

Publication number: CN114974110A
Application number: CN202210450613.XA
Authority: CN
Inventors: 孔祥永
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2022-04-26
Filing date: 2022-04-26
Publication date: 2022-08-30
Also published as: WO2023207195A1

Abstract

The embodiment of the application discloses a pixel driving circuit, a control method, a display screen and display equipment, wherein the pixel driving circuit comprises: a first initialization transistor, a first electrode of which is respectively connected with the first electrode of the driving transistor and the anode of the light emitting device, and which initializes the first electrode of the driving transistor in response to a first initialization voltage signal in a driving initialization stage; and initializing an anode of the light emitting device in response to the second initialization voltage signal of the light emission initialization stage. By implementing the pixel driving circuit, the problems of smear and short residue of the display screen in the data refreshing stage can be effectively relieved.

Description

Pixel driving circuit, control method, display screen and display device

Technical Field

The present application relates to the field of display technologies, and in particular, to a pixel driving circuit, a control method, a display screen, and a display device.

Background

In general, when a display screen displays a frame, the voltages of the driving transistors in each row are often different, so that the states of the driving transistors in each row are inconsistent, which often causes the display screen to have the problems of smear and short residue in the data refresh phase.

Disclosure of Invention

The embodiment of the application provides a pixel driving circuit, a control method, a display screen and display equipment, and can effectively solve the problems of smear and short residue of the display screen in a data refreshing stage.

A first aspect of an embodiment of the present application provides a pixel driving circuit, including:

a first initialization transistor, a first electrode of which is connected with a first electrode of the driving transistor and an anode of the light emitting device, respectively, and which initializes the first electrode of the driving transistor in response to a first initialization voltage signal at a driving initialization stage; and initializing an anode of the light emitting device in response to a second initialization voltage signal of a light emission initialization stage.

A second aspect of the embodiments of the present application provides a method for controlling a pixel driving circuit, where the method is applied to the pixel driving circuit, and the method includes:

in the process that the pixel driving circuit is in the driving initialization phase of the data refreshing phase, a first initialization voltage signal is input to a first initialization transistor, so that the first initialization voltage signal is input to the first pole of a driving transistor through the first initialization transistor

And inputting a second initialization voltage signal to the first initialization transistor in the process that the pixel driving circuit is in a light-emitting initialization phase of the data refreshing phase, so that the second initialization voltage signal is input to the anode of the light-emitting device through the first initialization transistor.

A third aspect of the embodiments of the present application provides a display screen, including:

the pixel drive circuit as disclosed in the first aspect;

and the light-emitting device is connected with the pixel driving circuit and used for receiving the driving current output by the pixel driving circuit and emitting light under the control of the driving current.

A fourth aspect of the embodiments of the present application provides a display device, which includes the display screen of the third aspect.

According to the technical scheme, the embodiment of the application has the following advantages:

the pixel driving circuit disclosed in the embodiment of the present application includes: a first initialization transistor, a first electrode of which is respectively connected with the first electrode of the driving transistor and the anode of the light emitting device, and which initializes the first electrode of the driving transistor in response to a first initialization voltage signal in a driving initialization stage; and initializing an anode of the light emitting device in response to the second initialization voltage signal of the light emission initialization stage. On one hand, in the drive initialization stage, the first initialization transistor can be used for initializing the drive transistor, so that the states of all the drive transistors in each row can be kept as consistent as possible, and the problems of smear and short residue of the display screen in the data refreshing stage are effectively relieved; initializing the anode of the light emitting device with the first initialization transistor in the light emission initialization stage may improve the stability of the luminance of the light emitting device in the data refresh stage. On the other hand, initialization of the light emitting device and the driving transistor is realized by multiplexing the first initialization transistor, and the circuit can be simplified.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the embodiments and the drawings used in the description of the prior art, and obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to the drawings.

Fig. 1 is a schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application;

FIG. 2 is another schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application;

fig. 3 is a diagram of the defect state variation of any two driving transistors T0 in a row;

FIG. 4 is a schematic diagram of a pixel driving circuit according to an embodiment of the present disclosure;

FIG. 5A is a timing diagram of a pixel driving circuit in a data refresh phase according to the disclosure of the present application;

FIG. 5B is another timing diagram of the pixel driving circuit during a data refresh phase according to the embodiment of the present disclosure;

fig. 5C is a schematic diagram of an operation mode of a display device disclosed in an embodiment of the present application;

fig. 5D is a graph showing a change in luminance of the light emitting device OLED at a refresh rate of 40Hz without initializing the driving transistor T0;

fig. 5E is a graph showing the luminance change of the light emitting device OLED after the driving transistor T0 is initialized at a refresh rate of 40 Hz;

fig. 5F is a timing diagram of the pixel driving circuit in the data holding phase according to the embodiment of the present application.

Detailed Description

To facilitate an understanding of the embodiments of the present application, the embodiments of the present application will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present application are shown in the drawings. The embodiments of the present application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application belong. The terminology used herein in the description of the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the present application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the description of the embodiments of the present application, it is to be understood that the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on methods or positional relationships shown in the drawings, and are only used for convenience in describing the embodiments of the present application and simplifying the description, but do not indicate or imply that the devices or elements referred to must have specific orientations, be constructed in specific orientations, and be operated, and thus, should not be construed as limiting the embodiments of the present application.

It will be understood that, as used herein, the terms "first," "second," and the like may be used herein 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, the seventh initialization transistor may be referred to as the second initialization transistor, and similarly, the second initialization transistor may be referred to as the seventh initialization transistor, without departing from the scope of the present application. The seventh initialization transistor and the second initialization transistor are both transistors, but they are not the same transistor.

The term "connected" in the description and claims of the present application is an electrical connection, and the transistors used in all embodiments of the present application can be transistors, thin film transistors, or field effect transistors or other devices with the same characteristics. In the embodiment of the present application, in order to distinguish two poles of a transistor except for a control pole, one pole is referred to as a first pole, and the other pole is referred to as a second pole.

In some embodiments, the transistor may be a transistor, the control electrode of the transistor may be a base electrode, the first electrode of the transistor may be a collector electrode, and the second electrode of the transistor may be an emitter electrode; alternatively, the control electrode of the transistor may be the base electrode, the first electrode of the transistor may be the emitter electrode, and the second electrode of the transistor may be the collector electrode.

In practical operation, when the transistor is a thin film transistor or a field effect transistor, the control electrode may be a gate electrode, the first electrode may be a drain electrode, and the second electrode may be a source electrode; alternatively, the control electrode may be a gate electrode, the first electrode may be a source electrode, and the second electrode may be a drain electrode.

The pixel driving circuit of the embodiment of the application is used for driving the light emitting device in the display device to emit light, so that the display device displays a picture. The display device may be a smartphone, a tablet, a gaming device, an Augmented Reality (AR) device, a notebook, a desktop computing device, a wearable device, or the like. For convenience of understanding, the display device is exemplified as a mobile phone in the following.

The Light Emitting device in the embodiment of the present application may include, but is not limited to, Organic Light-Emitting Diodes (OLEDs), Quantum Dot Light Emitting Diodes (QLEDs), Micro Light Emitting Diodes (Micro LEDs), sub-millimeter Light Emitting Diodes (mini LEDs), and the like. In addition, the embodiments of the present application are described by taking the light emitting device as an organic light emitting diode OLED as an example.

It should be noted that the driving initialization phase, the data writing phase, the light emitting initialization phase, and the light emitting phase disclosed in the embodiments of the present application all belong to a data refreshing phase, and the data refreshing phase refers to a phase in which a display screen updates a display screen. The data holding period refers to a period in which the driving transistor T0 continues to hold the driving current outputted during the data refresh period, and drives the light emitting device OLED to stably emit light.

The following describes the various stages of the data refresh phase: the driving initialization phase is for initializing the driving transistor T0. The light emission initialization phase is for initializing the anode of the light emitting device OLED. The data writing phase is used for storing the data signal voltage required by the light-emitting phase. The light emitting phase is used for driving the light emitting device OLED to emit light by using the driving current output from the driving transistor T0.

In this embodiment, the driving initialization is before the light emitting initialization, and the data writing phase may be before or after the light emitting initialization, which is not limited in this embodiment. The following description will be mainly made before the data writing phase is the light emission initialization phase.

Further, the light emission phase may be after the light emission initialization phase before the data writing phase is after the light emission initialization phase. At this time, the flow sequence of the data refreshing stage is a driving initialization stage, a data writing stage, a light emitting initialization stage and a light emitting stage.

It should be noted that, please refer to the following description for details regarding the specific operation states of the pixel driving circuit in the data refreshing stage (the driving initialization stage, the data writing stage, the light emitting initialization stage, and the light emitting stage) and the data holding stage.

Referring to fig. 1, fig. 1 is a schematic diagram of a pixel driving circuit according to an embodiment of the disclosure. The pixel driving circuit shown in fig. 1 includes a driving transistor T0, a first initializing transistor T1, and a light emitting device OLED. Wherein, the first pole of the first initializing transistor T1 is connected to the first pole of the driving transistor and the anode of the light emitting device OLED, respectively, and the cathode of the light emitting device OLED is grounded to ELVSS.

The first initializing transistor T1 initializes the first pole of the driving transistor T0 in response to the first initializing voltage signal vint1 of the driving initializing period, and initializes the anode of the light emitting device OLED in response to the second initializing voltage signal vint2 of the light emitting initializing period.

In some embodiments, the first initialization voltage signal vint1 is-2V-6V.

In some embodiments, the second initialization voltage signal vint2 is-2V-7V.

The initialization process for the first pole of the driving transistor T0 is: the first pole of the first initialization transistor T1 receives the first initialization voltage signal vint1, and the control pole of the first initialization transistor T1 generates a turn-on signal under the action of the first scan signal scan1, so that the first pole and the second pole of the first initialization transistor T1 are turned on, and thus the first initialization voltage signal vint1 can be from the second pole to the first pole of the first initialization transistor T1, i.e., the first pole of the driving transistor T0, thereby achieving the purpose of initializing the driving transistor T0.

The initialization process for the anode of the light emitting device OLED is: the first electrode of the first initializing transistor T1 receives the second initializing voltage signal vint2, and the control electrode of the first initializing transistor T1 generates a turn-on signal under the action of the first scan signal scan1 to turn on the first electrode and the second electrode of the first initializing transistor T1, so that the second initializing voltage signal vint2 can go from the second electrode to the first electrode of the first initializing transistor T1, i.e., the anode of the light emitting device OLED, thereby achieving the purpose of initializing the anode of the light emitting device OLED.

In summary, the first initialization transistor T1 is turned on in both the driving initialization period and the light emitting initialization period.

On one hand, in the drive initialization stage, the first initialization transistor can be used for initializing the drive transistor, so that the states of all the drive transistors in each row can be kept as consistent as possible, and the problems of smear and short residue of the display screen in the data refreshing stage are effectively relieved; initializing the anode of the light emitting device with the first initialization transistor in the light emission initialization stage may improve the stability of the luminance of the light emitting device in the data refresh stage. On the other hand, initialization of the light emitting device and the driving transistor is realized by multiplexing the first initialization transistor, and the circuit can be simplified.

Referring to fig. 2, fig. 2 is another schematic diagram of a pixel driving circuit disclosed in the present application. The pixel drive circuit shown in fig. 2 is an optimization of the pixel drive circuit shown in fig. 1. Note that the pixel driving circuit shown in fig. 2 includes a second initialization transistor T2, a third initialization transistor T3, and a fourth initialization transistor T4 in addition to the devices shown in fig. 1. A first electrode of the second initializing transistor T2 is connected to the first electrode of the driving transistor T0 and the first electrode of the first initializing transistor T1, respectively, and a second electrode of the second initializing transistor T2 is connected to the anode of the light emitting device OLED.

The second initializing transistor T2 makes the second initializing voltage signal vint2 transmitted to the anode of the light emitting device OLED by the first initializing transistor T1 in response to the turn-on signal of the light emitting initializing period to initialize the anode of the light emitting device OLED.

In some embodiments, the gate of the second initialization transistor T2 generates a turn-on signal under the action of the first emission control signal EM 1.

In summary, in the light emitting initialization stage, the first initialization transistor T1 and the second initialization transistor T2 in the pixel driving circuit shown in fig. 2 are both turned on.

In some embodiments, in the driving initialization phase, in addition to initializing the first pole of the driving transistor T0, the second pole and the control pole of the driving transistor T0 may be initialized. The initialization of the second and control electrodes of the driving transistor T0 will be described below with reference to the pixel driving circuit shown in fig. 2:

in the pixel driving circuit shown in fig. 2, a first electrode of the third initialization transistor T3 is connected to the control electrode of the driving transistor T0, and a second electrode of the third initialization transistor T3 is connected to the first electrode of the driving transistor T0 and the first electrode of the first initialization transistor T1, respectively; a first pole of the fourth initializing transistor T4 is connected to the second pole of the driving transistor T0;

the fourth initialization transistor T4 initializes the second pole of the driving transistor T0 in response to the third initialization voltage signal vint3 during the driving initialization period.

It should be noted that, in the driving initialization phase, the first pole of the fourth initialization transistor T4 receives the third initialization voltage signal vint3, and at the same time, the control pole of the fourth initialization transistor T4 generates a turn-on signal under the action of the second scan signal scan2 to turn on the first pole and the second pole of the fourth initialization transistor T4, so that the third initialization voltage signal vint3 can reach the second pole of the fourth initialization transistor T4, that is, the second pole of the driving transistor T0 from the first pole of the fourth initialization transistor T4, thereby implementing the initialization of the second pole of the driving transistor T0.

The third initialization transistor T3 initializes the gate of the driving transistor T0 in response to the on signal during the driving initialization phase;

it should be noted that, in the driving initialization phase, the control electrode of the third initialization transistor T3 generates a turn-on signal under the control of the third scan signal scan3 to turn on the first electrode and the second electrode of the third initialization transistor T3, so that the first initialization voltage signal vint1 flowing through the first electrode of the driving transistor T0 can be applied; alternatively, the initialization of the control electrode of the driving transistor T0 is achieved by the third initialization voltage signal vint3 flowing through the second electrode of the driving transistor T0.

In some embodiments, the driving initialization phase may include a first initialization sub-phase and a second initialization sub-phase, and the operation states of the pixel driving circuit in the first initialization sub-phase and the second initialization sub-phase are described below with reference to fig. 2:

in the first initialization sub-phase, the third initialization transistor T3, the fourth initialization transistor T4 and the driving transistor T0 are all turned on. At this time, the voltage of the second pole of the driving transistor T0 is the third initialization voltage signal vint3 received by the fourth initialization transistor T4, and meanwhile, the driving transistor T0 is in a diode operating state, and the voltages of the first pole and the control pole of the driving transistor T0 can both be the first target voltage, thereby completing the initialization of the driving transistor T0. The first target voltage is obtained by adding the threshold voltage of the driving transistor T0 to the third initialization voltage signal vint 3. It should be noted that, through the first initialization sub-stage, the consistency of the defect states of the driving transistors T0 in each row on the display screen can be made higher.

In some embodiments, the third initialization voltage signal vint3 may be related to the voltage of the data signal data, which may generally range from 0V to 6V, the third initialization voltage signal vint3 may range from 0V to 6V, and the third initialization voltage signal vint3 may be 0V, 5V, or 6V, for example.

In the second initialization sub-phase, the first initialization transistor T1, the third initialization transistor T3, the fourth initialization transistor T4 and the driving transistor T0 are all turned on. At this time, the voltage of the second electrode of the driving transistor T0 is the third initialization voltage signal vint3 received by the fourth initialization transistor T4, and the voltages of the first electrode and the control electrode of the driving transistor T0 are both the first initialization voltage signal vint1 received by the first initialization transistor T1. It should be noted that, on the basis of the first initialization sub-phase, the driving transistor T0 is continuously initialized again in the second initialization sub-phase, so that the number of defect states of the driving transistors T0 in each row can be further reduced, and the problems of smear and short residue of the display panel in the data refresh phase can be further effectively alleviated.

Next, referring to fig. 3, the defect state change of any two driving transistors T0 in a row will be described as an example. Since the driving currents of the two driving transistors T0 are different when displaying a picture of a previous frame, there is a difference in the defect state conditions of the two driving transistors T0. After the first initialization sub-stage, the defect states of the two driving transistors T0 can be kept consistent, and after the second initialization sub-stage, the defect states of the two driving transistors T0 can be greatly improved.

By implementing the pixel driving circuit shown in fig. 2, on one hand, in the driving initialization stage, the first initialization transistor can be used to initialize the driving transistor, so that the states of the driving transistors in each row can be kept as consistent as possible, and the problems of smear and short residue of the display screen in the data refreshing stage are effectively alleviated; initializing the anode of the light emitting device with the first initialization transistor in the light emission initialization stage may improve the stability of the luminance of the light emitting device in the data refresh stage. On the other hand, initialization of the light emitting device and the driving transistor is realized by multiplexing the first initialization transistor, and the circuit can be simplified. In another aspect, initializing each driving transistor of each row twice can effectively improve the defect state of the driving transistor T0, and is beneficial to further alleviating the problems of smear and short residue of the display screen in the data refresh stage.

The driving initialization phase and the light-emitting initialization phase are mainly described above, and the data writing phase and the light-emitting phase are described below with reference to fig. 4.

Fig. 4 is a schematic diagram of a pixel driving circuit disclosed in the embodiment of the present application. The pixel drive circuit shown in fig. 4 is an optimization of the pixel drive circuit shown in fig. 2. The pixel driving circuit shown in fig. 4 includes a fifth transistor T5, a storage capacitor C, and a sixth transistor T6 in addition to the devices shown in fig. 2. A first electrode of the fifth transistor T5 is connected to the second electrode of the driving transistor T0, a first end of the storage capacitor C is used for obtaining the power voltage ELVDD, and is connected to the first electrode of the sixth transistor T6, and a second end of the storage capacitor C is respectively connected to the control electrode of the driving transistor T0 and the first electrode of the third initialization transistor T3. A first pole of the sixth transistor T6 is used to obtain the power supply voltage ELVDD, and a second pole of the sixth transistor T6 is connected to the second pole of the driving transistor T0.

The fifth transistor T5 writes the data signal data to the second pole of the driving transistor T0 in response to the data write signal in the data write phase.

During the data writing phase, the second pole of the fifth transistor T5 receives the data signal data, and the control pole of the fifth transistor T5 generates a turn-on signal under the action of the fourth scan signal scan4 to turn on the first pole and the second pole of the fifth transistor T5, so that the data signal data can reach the first pole of the fifth transistor T5, i.e., the second pole of the driving transistor T0, from the second pole of the fifth transistor T5.

And the storage capacitor C is used for storing charges in a data writing phase, and the stored charge quantity is positively correlated with the voltage of the data signal. The storage capacitor C stores the same amount of charge as the data signal.

The operation of the pixel driving circuit shown in fig. 4 in the data writing phase is explained as follows: the third initialization transistor T3, the driving transistor T0, and the fifth transistor are all turned on. The data signal data is transmitted from the second pole of the fifth transistor T5 to the first pole of the fifth transistor T5 (i.e., the second pole of the driving transistor T0), and at this moment, the driving transistor T0 is in the diode operating state, so that the voltages of the first pole and the second pole of the driving transistor T0 are both the second target voltage, which is the sum of the voltage of the data signal data and the threshold voltage of the driving transistor T0. Since the second terminal of the storage capacitor C is connected to the driving transistor T0, the data signal data can be written into the storage capacitor C, so that the storage capacitor C stores the amount of charge corresponding to the data signal.

The sixth transistor T6 responds to the turn-on signal during the light emitting period to make the driving transistor T0 generate the driving current by the amount of stored charge and the power voltage ELVDD.

The second initializing transistor T2 responds to the turn-on signal of the light emitting period to input the driving current generated by the driving transistor T0 to the anode of the light emitting device OLED.

In some embodiments, the control electrode of the sixth transistor T6 may generate a turn-on signal under the action of the second emission control signal EM2, so that the first and second electrodes of the sixth transistor T6 are turned on.

The following describes the operation of the pixel driving circuit in the light-emitting stage in the pixel driving circuit shown in fig. 4: the driving transistor T0, the sixth transistor T6, and the second initialization transistor T2 are turned on. When the sixth transistor T6 is turned on, the driving transistor T0 may generate a driving current by the amount of charge discharged from the storage capacitor C and the power supply voltage ELVDD; when the second initializing transistor T2 is turned on, a driving current is inputted to the anode of the light emitting device OLED by the driving transistor T0.

In some embodiments, the driving transistor T0, the first initialization transistor T1, the second initialization transistor T2, the third initialization transistor T3, the fourth initialization transistor T4, the fifth transistor T5 and the sixth transistor T6 may all be low temperature polysilicon thin film transistors. The enabling mode of the low-temperature polysilicon thin film transistor is high-level off and low-level on, and has the advantage of fast response, so that the transistors in the pixel driving circuit shown in fig. 4 are all low-temperature polysilicon thin film transistors, which is beneficial to improving the response efficiency of the whole circuit.

In some embodiments, the third initialization transistor T3 may be an oxide thin film transistor. Since the enabling mode of the oxide thin film transistor is off at a low level and on at a high level, and has an advantage of suppressing leakage, if the third initialization transistor T3 is an oxide thin film transistor in the pixel driving circuit shown in fig. 4, leakage of the pixel driving circuit can be effectively prevented.

Referring to fig. 5A-5B, fig. 5A-5B are timing diagrams of a pixel driving circuit in a data refresh period according to an embodiment of the disclosure. The timing diagrams shown in fig. 5A-5B each include a first initialization sub-phase t1, a first initialization sub-phase t2, a data writing phase t3, a light emission initialization phase t4, and a light emission phase t 5. In the pixel driving circuit corresponding to fig. 5A, the third initialization transistor T3 is a low temperature polysilicon thin film transistor. In the pixel driving circuit corresponding to fig. 5B, the third initialization transistor T3 is an oxide thin film transistor.

The operation of the pixel driving circuit shown in fig. 4 in the data refresh phase is described below with reference to the timing chart shown in fig. 5A:

first initialization sub-phase t 1: the second scan signal scan2 and the third scan signal scan3 are all low, so that the driving transistor T0, the third initialization transistor T3, and the fourth initialization transistor T4 are all turned on.

Second initialization sub-phase t 2: the first scan signal scan1, the second scan signal scan2 and the third scan signal scan3 are all low, so that the driving transistor T0, the third initialization transistor T3, the fourth initialization transistor T4 and the first initialization transistor T1 are all turned on.

Data write phase t 3: the third scan signal scan3 and the fourth scan signal scan4 are low, such that the third initialization transistor T3, the driving transistor T0 and the fifth transistor T5 are all turned on.

Light emission initialization phase t 4: the first emission control signal EM1 and the first scan signal scan1 are low level, so that the first and second initialization transistors T1 and T2 are turned on.

Lighting phase t 5: the first and second light emission control signals EM1 and EM2 are at a level such that the fifth transistor T5, the sixth transistor T6, and the driving transistor T0 are all turned on.

The operation state of the pixel driving circuit shown in fig. 4 in the data refresh period is described below with reference to the timing chart shown in fig. 5B:

first initialization sub-phase t 1: the second scan signal scan2 is at a low level, and the third scan signal scan3 is at a high level, so that the driving transistor T0, the third initialization transistor T3 and the fourth initialization transistor T4 are all turned on.

Second initialization sub-phase t 2: the first and second scan signals scan1 and scan2 are at a low level, and the third scan signal scan3 is at a high level, so that the driving transistor T0, the third initializing transistor T3, the fourth initializing transistor T4, and the first initializing transistor T1 are all turned on.

Data write phase t 3: the third scan signal scan3 is at a high level, and the fourth scan signal scan4 is at a low level, so that the third initialization transistor T3, the driving transistor T0, and the fifth transistor T5 are all turned on.

Currently, the display modes of the display device may include a high frequency display mode and a low frequency display mode. The high-frequency display mode may be a display mode with a refresh rate greater than or equal to 120Hz (hertz), in which the data signal is updated once per pixel in no more than 0.0083 seconds, and the display device is continuously in a data refresh phase. The low-frequency display mode may be a display mode with a refresh rate less than 120Hz, in which each pixel updates the data signal for more than 0.0083 seconds, and the display device is periodically in a data refresh phase and a data hold phase. Referring to fig. 5C, fig. 5C is a schematic diagram illustrating an operation mode of a display device according to an embodiment of the present disclosure. The schematic diagram shown in FIG. 5C includes a display mode with a refresh rate of 120Hz, a display mode with a refresh rate of 60Hz, and a display mode with a refresh rate of 40 Hz.

It should be noted that, in the Data holding phase, the driving transistor T0 does not receive the Data signal Data, and keeps the driving current at this time the same as the driving current in the Data refreshing phase, so as to continuously drive the light emitting device OLED to stably emit light. However, in the data holding phase, the voltage outside the driving transistor T0 may shift the output characteristic curve of the driving transistor T0, and accordingly, the brightness of the light emitting device OLED may also change, which is perceived by the user as a flicker phenomenon, and thus the viewing experience of the user may be affected.

To solve this problem, the fourth initialization transistor T4 initializes the second pole of the driving transistor T0 in response to the fourth initialization voltage signal vint4 during the data holding period, so as to effectively compensate the drift of the output characteristic of the driving transistor T0, which is beneficial to alleviating the flicker phenomenon.

In some embodiments, the fourth initialization voltage signal vint4 is 4V-7V.

Referring to fig. 5D to 5E, fig. 5D is a graph illustrating the luminance variation of the light emitting device OLED when the driving transistor T0 is not initialized at the refresh rate of 40 Hz. Fig. 5E is a graph showing a change in luminance of the light emitting device OLED after the driving transistor T0 is initialized at a refresh rate of 40 Hz.

In some embodiments, the first initializing transistor T1, initializing the anode of the light emitting device OLED in response to the second initializing voltage signal vint2 during the data holding period, may ensure the stability of the luminance of the light emitting device during the data holding period. It should be noted that the initialization process of the first initialization transistor T1 for the anode of the light emitting device OLED in the data holding phase may be the same as the initialization process of the first initialization transistor T1 for the anode of the light emitting device OLED in the light emitting initialization phase, and thus, the description thereof is omitted.

Referring to fig. 5F, fig. 5F is a timing diagram of the pixel driving circuit in the data holding phase according to the disclosure of the present application. The pixel driving circuit shown in fig. 5F may be the same as the pixel driving circuit corresponding to fig. 5A/5B.

The operation of the pixel driving circuit shown in fig. 4 in the data holding phase will be described with reference to the timing chart shown in fig. 5F: the first and second emission control signals EM1 and EM2 are both high first, and at this time, the second scan signal scan2 is low, so that the fourth initialization transistor T4 is turned on to initialize the driving transistor T0. Then, the first emission control signal EM1 is changed to a low level prior to the second emission control signal EM2, and at the same time, the first scan signal scan1 is changed to a low level, so that both the first initialization transistor T1 and the second initialization transistor T2 are turned on to initialize the anode of the light emitting device OLED. Finally, the first emission control signal EM1 keeps on keeping at the low level, the second emission control signal EM2 changes from the high level to the low level, and at this time, the sixth transistor T6, the second initialization transistor T2 and the driving transistor T0 are all turned on, so that the light emitting device OLED emits light.

By implementing the pixel driving circuit shown in fig. 4, on one hand, in the driving initialization stage, the driving transistors can be initialized by using the first initialization transistor, so that the states of the driving transistors in each row can be kept as consistent as possible, and the problems of smear and short residue of the display screen in the data refreshing stage are effectively alleviated; initializing the anode of the light emitting device with the first initialization transistor in the light emission initialization stage may improve the stability of the luminance of the light emitting device in the data refresh stage. On the other hand, initialization of the light emitting device and the driving transistor is realized by multiplexing the first initialization transistor, and the circuit can be simplified. In another aspect, initializing each driving transistor of each row twice can effectively improve the defect state of the driving transistor T0, and is beneficial to further alleviating the problems of smear and short residue of the display screen in the data refresh stage. In another aspect, in the data holding stage, the driving transistor and the anode of the light emitting device are initialized, so that the drift of the output characteristic of the driving transistor can be effectively compensated, and the flicker phenomenon can be favorably relieved.

The embodiment of the application discloses a control method of a pixel driving circuit, wherein in the process that the pixel driving circuit is in a driving initialization stage, a first initialization voltage signal is input to a first initialization transistor, so that the first initialization voltage signal is input to a first pole of the driving transistor through the first initialization transistor, and the first pole of the driving transistor is initialized;

and inputting a second initialization voltage signal to the first initialization transistor during the light emitting initialization phase of the pixel driving circuit, so that the second initialization voltage signal is input to the anode of the light emitting device through the first initialization transistor to initialize the anode of the light emitting device.

In some embodiments, during the light emission initialization phase, an on signal is input to the second initialization transistor so that the second initialization voltage signal is transmitted to the anode of the light emitting device by the first initialization transistor.

In some embodiments, in the driving initialization phase, it is also possible to input a turn-on signal to the third initialization transistor to initialize the control electrode of the driving transistor, and to input a third initialization voltage signal to the fourth initialization transistor to input the third initialization voltage signal to the second electrode of the driving transistor through the fourth initialization transistor to initialize the second electrode of the driving transistor.

In some embodiments, the drive initialization phase includes a first initialization sub-phase and a second initialization sub-phase;

in the second initialization sub-phase, a first initialization voltage signal is input to the first initialization transistor, so that the first initialization voltage signal is input to the first pole of the driving transistor through the first initialization transistor.

And inputting a conducting signal to the third initialization transistor in the first initialization sub-phase and the second initialization sub-phase to initialize the control electrode of the driving transistor.

In the first and second initialization sub-stages, the third initialization voltage signal is input to the fourth initialization transistor to be input to the second pole of the driving transistor through the fourth initialization transistor.

In some embodiments, in the data writing phase, a data writing signal is input to the fifth transistor to write the data signal to the second pole of the driving transistor through the fifth transistor, and the storage capacitor stores electric charge, and the amount of the stored electric charge is positively correlated with the voltage of the data signal.

In some embodiments, during the light emitting period, an on signal is input to the sixth transistor and the second initialization transistor, respectively, to cause the driving transistor to generate a driving current under the action of the stored charge amount and the power supply voltage, and the driving current is transmitted to the anode of the light emitting device through the second initialization transistor.

In some embodiments, during the data holding phase, the second initialization voltage signal may be further input to the first initialization transistor and transmitted to the anode of the light emitting device through the first initialization transistor.

In some embodiments, during the data holding phase, a fourth initialization voltage signal may be further input to the fourth initialization transistor and transmitted to the second pole of the driving transistor by the fourth initialization voltage signal.

In some embodiments, the fourth initialization voltage signal is 4V to 7V.

The embodiment of the application discloses a display screen, which comprises the pixel driving circuit and the light-emitting device disclosed by the embodiment, wherein the light-emitting device is connected with the pixel driving circuit and used for receiving the driving current output by the pixel driving circuit and emitting light under the control of the driving current.

The embodiment of the application discloses display equipment, and the display equipment comprises the display screen.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express a few embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the concept of the embodiments of the present application, several variations and modifications can be made, which all fall within the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the appended claims.

Claims

1. A pixel driving circuit, comprising:

a first initialization transistor, a first electrode of which is connected with a first electrode of the driving transistor and an anode of the light emitting device, respectively, and which initializes the first electrode of the driving transistor in response to a first initialization voltage signal at a driving initialization stage; and initializing an anode of the light emitting device in response to a second initialization voltage signal of the light emission initialization stage.

2. The pixel driving circuit according to claim 1, further comprising:

and a second initialization transistor, a first pole of the second initialization transistor being connected to the first pole of the driving transistor and the first pole of the first initialization transistor, respectively, and a second pole of the second initialization transistor being connected to the anode of the light emitting device, such that the second initialization voltage signal is transmitted from the first initialization transistor to the anode of the light emitting device in response to the turn-on signal during the light emission initialization phase to initialize the anode of the light emitting device.

3. The pixel driving circuit according to claim 1, further comprising:

a third initialization transistor, a first electrode of the third initialization transistor being connected to the control electrode of the driving transistor, a second electrode of the third initialization transistor being connected to the first electrode of the driving transistor and the first electrode of the first initialization transistor, respectively, and initializing the control electrode of the driving transistor in response to a turn-on signal in the driving initialization stage;

a fourth initialization transistor, a first pole of which is connected to the second pole of the driving transistor, and which initializes the second pole of the driving transistor in response to a third initialization voltage signal of the driving initialization stage.

4. The pixel driving circuit according to claim 3, wherein the driving initialization phase comprises a first initialization sub-phase and a second initialization sub-phase;

the first initialization transistor is used for responding to a first initialization voltage signal of the second initialization sub-phase and initializing the first pole of the driving transistor;

the third initialization transistor is used for responding to the conducting signals of the first initialization sub-phase and the second initialization sub-phase and initializing the control electrode of the driving transistor;

the fourth initialization transistor initializes a second pole of the driving transistor in response to a third initialization voltage signal of the first initialization sub-phase and the second initialization sub-phase.

5. The pixel driving circuit according to claim 3, further comprising:

a fifth transistor, a first pole of which is connected to the second pole of the driving transistor, for writing a data signal into the second pole of the driving transistor in response to a data write signal in a data write phase; the data writing phase is after the driving initialization phase;

and the first end of the storage capacitor is used for acquiring power supply voltage, the second end of the storage capacitor is respectively connected with the control electrode of the driving transistor and the first electrode of the third initialization transistor and used for storing charges in the data writing stage, and the stored charge quantity is positively correlated with the voltage of the data signal.

6. The pixel driving circuit according to claim 5, further comprising:

a sixth transistor, a first pole of which is used for obtaining a power supply voltage and is connected to the first end of the storage capacitor, and a second pole of which is connected to the second pole of the driving transistor, and which responds to a turn-on signal in a light-emitting phase so that the driving transistor generates a driving current under the action of the stored charge amount and the power supply voltage; wherein the light emission phase is after the data writing phase;

the second initialization transistor, in response to the on signal of the light emitting phase, enables the driving current generated by the driving transistor to be input to the anode of the light emitting device.

7. The pixel driving circuit according to any of claims 1 to 6, wherein the first initialization transistor initializes an anode of the light emitting device in response to the second initialization voltage signal in a data holding period.

8. The pixel driving circuit according to any of claims 3 to 6, wherein the fourth initialization transistor initializes the second pole of the driving transistor in response to a fourth initialization voltage signal during the data hold phase.

9. The pixel driving circuit according to claim 8, wherein the fourth initialization voltage signal is 4V to 7V.

10. A control method of a pixel driving circuit is applied to the pixel driving circuit, and the method comprises the following steps:

in the process that the pixel driving circuit is in a driving initialization stage, inputting a first initialization voltage signal to a first initialization transistor so as to input the first initialization voltage signal to a first pole of a driving transistor through the first initialization transistor

And in the process that the pixel driving circuit is in a light-emitting initialization phase, inputting a second initialization voltage signal to the first initialization transistor so as to input the second initialization voltage signal to the anode of the light-emitting device through the first initialization transistor.

11. A display screen, comprising:

a pixel driving circuit according to any one of claims 1 to 9;

12. A display device characterized in that it comprises a display screen as claimed in claim 11.