CN114974110B - Pixel driving circuit, control method, display screen and display device - Google Patents

Abstract

The embodiment of the present application discloses a pixel driving circuit, a control method, a display screen and a display device, wherein the pixel driving circuit comprises: a first initialization transistor, wherein the first electrode of the first initialization transistor is respectively connected to the first electrode of the driving transistor and the anode of the light-emitting device, and the first electrode of the driving transistor is initialized in response to a first initialization voltage signal in the driving initialization stage; and the anode of the light-emitting device is initialized in response to a second initialization voltage signal in the light-emitting initialization stage. The implementation of the pixel driving circuit can effectively alleviate the problems of smear and short residue of the display screen during the data refresh stage.

Description

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

Technical Field

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

Background Art

Normally, when a display screen is displaying the previous frame, the voltage of the driving transistors in each row is often different, resulting in inconsistent states of the driving transistors in each row, which often causes the display screen to have problems such as ghosting and short image retention during the data refresh phase.

Summary of the invention

The embodiments of the present application provide a pixel driving circuit, a control method, a display screen and a display device, which can effectively alleviate the problems of ghosting and short image retention of the display screen during the data refresh stage.

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

A first initialization transistor, wherein the first electrode of the first initialization transistor is respectively connected to the first electrode of the driving transistor and the anode of the light-emitting device, and the first electrode of the driving transistor is initialized in response to a first initialization voltage signal in a driving initialization stage; and the anode of the light-emitting device is initialized in response to a second initialization voltage signal in a light-emitting initialization stage.

A second aspect of an embodiment of the present application provides a control method for a pixel driving circuit, which is applied to the pixel driving circuit. The method includes:

During the driving initialization phase of the pixel driving circuit in the data refresh 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 electrode of the driving transistor through the first initialization transistor.

When the pixel driving circuit is in the light emitting initialization phase of the data refreshing phase, a second initialization voltage signal is input to the first initialization transistor, 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 driving circuit as disclosed in the first aspect;

The light emitting device is connected to the pixel driving circuit, and is used to receive the driving current output by the pixel driving circuit and emit light under the control of the driving current.

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

It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

The pixel driving circuit disclosed in the embodiment of the present application includes: a first initialization transistor, the first electrode of the first initialization transistor is respectively connected to the first electrode of the driving transistor and the anode of the light-emitting device, and the first electrode of the driving transistor is initialized in response to the first initialization voltage signal in the driving initialization stage; and the anode of the light-emitting device is initialized in response to the second initialization voltage signal in the light-emitting initialization stage. On the one hand, in the driving initialization stage, the first initialization transistor can also 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, effectively alleviating the problems of smear and short residue of the display screen in the data refresh stage; in the light-emitting initialization stage, the anode of the light-emitting device is initialized by the first initialization transistor, which can improve the stability of the brightness of the light-emitting device in the data refresh stage. On the other hand, the initialization of the light-emitting device and the driving transistor is achieved by reusing the first initialization transistor, which can simplify the circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments and the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained based on these drawings.

FIG1 is a schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application;

FIG2 is another schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application;

FIG3 is a diagram showing the defect state changes of any two driving transistors T0 in a row;

FIG4 is another schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application;

FIG5A is a timing diagram of a pixel driving circuit disclosed in an embodiment of the present application during a data refresh phase;

FIG5B is another timing diagram of the pixel driving circuit disclosed in the embodiment of the present application in the data refresh phase;

FIG5C is a schematic diagram of a working mode of a display device disclosed in an embodiment of the present application;

FIG5D is a diagram showing the brightness change of the light emitting device OLED when the refresh rate is 40 Hz and the driving transistor T0 is not initialized;

FIG5E is a diagram showing the brightness change of the light emitting device OLED after the driving transistor T0 is initialized when the refresh rate is 40 Hz;

FIG. 5F is a timing diagram of the pixel driving circuit disclosed in an embodiment of the present application during the data holding stage.

DETAILED DESCRIPTION

In order to facilitate understanding of the embodiments of the present application, the embodiments of the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the embodiments of the present application are given in the drawings. However, the embodiments of the present application can be implemented in many different forms and are not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the embodiments of the present application more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the embodiments of the present application. The terms used herein in the specification of the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The term "and/or" used herein includes any and all combinations of one or more related listed items.

In the description of the embodiments of the present application, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the methods or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, 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. Both the seventh initialization transistor and the second initialization transistor are transistors, but they are not the same transistor.

The "connection" in the specification and claims of this application refers to electrical connection. The transistors used in all embodiments of this application can be triodes, thin film transistors, field effect transistors or other devices with the same characteristics. In the embodiments of this application, in order to distinguish the two electrodes of the transistor except the control electrode, one of the electrodes is called the first electrode and the other is called the second electrode.

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

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

The pixel driving circuit of the embodiment of the present application is used to drive the light-emitting device in the display device to emit light, so that the display device displays a picture. The display device can be a smart phone, a tablet computer, a gaming device, an augmented reality (AR) device, a notebook, a desktop computing device, a wearable device, etc. For ease of understanding, the following example is taken as an example of a mobile phone as the display device.

The light-emitting devices in the embodiments of the present application may include but are not limited to organic light-emitting diodes (OLED), quantum dot light-emitting diodes (QLED), micron-sized light-emitting diodes (Micro LED), sub-millimeter light-emitting diodes (mini LED), etc. It should be noted that 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 stage, data writing stage, light emitting initialization stage and light emitting stage disclosed in the embodiment of the present application all belong to the data refresh stage, and the data refresh stage refers to the stage in which the display screen updates the display screen. The data retention stage refers to the stage in which the driving transistor T0 continues to maintain the driving current output during the data refresh stage, driving the light emitting device OLED to emit light stably.

The following describes each stage in the data refresh stage: the driving initialization stage is used to initialize the driving transistor T0. The light emitting initialization stage is used to initialize the anode of the light emitting device OLED. The data writing stage is used to store the data signal voltage required for the light emitting stage. The light emitting stage is used to drive the light emitting device OLED to emit light using the driving current output by the driving transistor T0.

In the embodiment of the present application, the driving initialization is before the light emitting initialization, and the data writing stage can be before or after the light emitting initialization, which is not limited in the embodiment of the present application. The following mainly describes that the data writing stage is before the light emitting initialization stage.

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

It should be noted that regarding the specific working status of the pixel driving circuit in the data refresh phase (driving initialization phase, data writing phase, light emitting initialization phase and light emitting phase) and the data retention phase, please refer to the following description in detail.

Please refer to FIG. 1, which is a schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application. As shown in FIG. 1, the pixel driving circuit includes a driving transistor T0, a first initialization transistor T1, and a light-emitting device OLED. Among them, the first electrode of the first initialization transistor T1 is respectively connected to the first electrode of the driving transistor and the anode of the light-emitting device OLED, and the cathode of the light-emitting device OLED is grounded ELVSS.

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

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 electrode of the driving transistor T0 is as follows: the first electrode of the first initialization transistor T1 receives the first initialization voltage signal vint1, and the control electrode of the first initialization transistor T1 generates a conduction signal under the action of the first scanning signal scan1, so that the first electrode and the second electrode of the first initialization transistor T1 are turned on. In this way, the first initialization voltage signal vint1 can be transmitted from the second electrode of the first initialization transistor T1 to the first electrode, that is, the first electrode 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 as follows: the first electrode of the first initialization transistor T1 receives the second initialization voltage signal vint2, and the control electrode of the first initialization transistor T1 generates a conduction signal under the action of the first scan signal scan1, so that the first electrode and the second electrode of the first initialization transistor T1 are turned on. In this way, the second initialization voltage signal vint2 can flow from the second electrode of the first initialization transistor T1 to the first electrode, that is, 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 stage and the light emitting initialization stage.

On the 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, effectively alleviating the problems of smear and short residue of the display screen in the data refresh stage; in the light emitting initialization stage, the anode of the light emitting device is initialized by the first initialization transistor, which can improve the stability of the brightness of the light emitting device in the data refresh stage. On the other hand, the initialization of the light emitting device and the driving transistor is realized by reusing the first initialization transistor, which can simplify the circuit.

Please refer to FIG. 2, which is another schematic diagram of the pixel driving circuit disclosed in the present application. The pixel driving circuit shown in FIG. 2 is an optimization of the pixel driving circuit shown in FIG. 1. It should be noted that, in addition to the device shown in FIG. 1, the pixel driving circuit shown in FIG. 2 also includes a second initialization transistor T2, a third initialization transistor T3, and a fourth initialization transistor T4. The first electrode of the second initialization transistor T2 is respectively connected to the first electrode of the driving transistor T0 and the first electrode of the first initialization transistor T1, and the second electrode of the second initialization transistor T2 is connected to the anode of the light-emitting device OLED.

The second initialization transistor T2 responds to the turn-on signal in the light emitting initialization stage, so that the second initialization voltage signal vint2 is transmitted from the first initialization transistor T1 to the anode of the light emitting device OLED to initialize the anode of the light emitting device OLED.

In some embodiments, the control electrode of the second initialization transistor T2 generates a turn-on signal under the action of the first light emitting control signal EM1.

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

In some embodiments, in the driving initialization stage, in addition to initializing the first electrode of the driving transistor T0, the second electrode and the control electrode of the driving transistor T0 may also be initialized. The initialization of the second electrode and the control electrode of the driving transistor T0 is described below in conjunction with the pixel driving circuit shown in FIG. 2:

In the pixel driving circuit shown in FIG2 , the first electrode of the third initialization transistor T3 is connected to the control electrode of the driving transistor T0, the second electrode of the third initialization transistor T3 is respectively connected to the first electrode of the driving transistor T0 and the first electrode of the first initialization transistor T1; the first electrode of the fourth initialization transistor T4 is connected to the second electrode of the driving transistor T0;

The fourth initialization transistor T4 initializes the second electrode of the driving transistor T0 in response to the third initialization voltage signal vint3 in the driving initialization phase.

It should be noted that, in the driving initialization stage, the first electrode of the fourth initialization transistor T4 receives the third initialization voltage signal vint3. At the same time, the control electrode of the fourth initialization transistor T4 generates a conduction signal under the action of the second scanning signal scan2, so that the first electrode and the second electrode of the fourth initialization transistor T4 are turned on. In this way, the third initialization voltage signal vint3 can be transmitted from the first electrode of the fourth initialization transistor T4 to the second electrode of the fourth initialization transistor T4, that is, the second electrode of the driving transistor T0, thereby realizing the initialization of the second electrode of the driving transistor T0.

The third initialization transistor T3 initializes the control electrode of the driving transistor T0 in response to the conduction signal in the driving initialization phase;

It should be noted that, in the driving initialization stage, the control electrode of the third initialization transistor T3 generates a turn-on signal under the control of the third scanning signal scan3, so that the first electrode and the second electrode of the third initialization transistor T3 are turned on. In this way, the control electrode of the driving transistor T0 can be initialized under the action of the first initialization voltage signal vint1 flowing through the first electrode of the driving transistor T0; or under the action of 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. The working states of the pixel driving circuit in the first initialization sub-phase and the second initialization sub-phase are described below in conjunction with FIG. 2 :

In the first initialization sub-stage, 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. At the same time, the driving transistor T0 is in a diode working state, and the voltages of the first electrode and the control electrode of the driving transistor T0 can both be the first target voltage, thereby completing the initialization of the driving transistor T0. Among them, the first target voltage is obtained by adding the third initialization voltage signal vint3 to the threshold voltage of the driving transistor T0. It should be noted that after the first initialization sub-stage, the defect state of the driving transistor T0 in each row on the display screen can be made more consistent.

In some embodiments, the third initialization voltage signal vint3 may be related to the voltage of the data signal data. The voltage range of the data signal data is generally 0V-6V. The range of the third initialization voltage signal vint3 may be 0V-6V. Exemplarily, the third initialization voltage signal vint3 is 0V, 5V or 6V.

In the second initialization sub-stage, 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 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-stage, continuing to initialize the driving transistor T0 again in the second initialization sub-stage can further reduce the number of defective states of the driving transistor T0 of each row, thereby further effectively alleviating the problems of smear and short residue of the display screen during the data refresh stage.

In conjunction with FIG3 , the defect state change of any two driving transistors T0 in a row is described as an example. Since the driving currents of the two driving transistors T0 are different when displaying the previous frame, the defect state conditions of the two driving transistors T0 are different. After the first initialization sub-stage, the defect state conditions of the two driving transistors T0 can remain consistent, and after the second initialization sub-stage, the defect state conditions of the two driving transistors T0 can be greatly improved.

By implementing the pixel driving circuit shown in FIG2, on the one hand, in the driving initialization stage, the first initialization transistor can also 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, effectively alleviating the problems of smearing and short residues of the display screen during the data refresh stage; in the light emitting initialization stage, the anode of the light emitting device is initialized by the first initialization transistor, which can improve the stability of the brightness of the light emitting device during the data refresh stage. On the other hand, the initialization of the light emitting device and the driving transistor is achieved by reusing the first initialization transistor, which can simplify the circuit. On the other hand, initializing each driving transistor in each row twice can effectively improve the defective state of the driving transistor T0, which is conducive to further alleviating the problems of smearing and short residues of the display screen during the data refresh stage.

The above mainly introduces the driving initialization stage and the light emitting initialization stage. The following introduces the data writing stage and the light emitting stage in conjunction with FIG. 4 .

FIG4 is another schematic diagram of a pixel driving circuit disclosed in an embodiment of the present application. The pixel driving circuit shown in FIG4 is an optimization of the pixel driving circuit shown in FIG2. In addition to the device shown in FIG2, the pixel driving circuit shown in FIG4 also includes a fifth transistor T5, a storage capacitor C, and a sixth transistor T6. Among them, the first electrode of the fifth transistor T5 is connected to the second electrode of the driving transistor T0, the first end of the storage capacitor C is used to obtain the power supply voltage ELVDD, and is connected to the first electrode of the sixth transistor T6, and the 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. The first electrode of the sixth transistor T6 is used to obtain the power supply voltage ELVDD, and the second electrode of the sixth transistor T6 is connected to the second electrode of the driving transistor T0.

The fifth transistor T5 writes the data signal data into the second electrode of the driving transistor T0 in response to the data writing signal in the data writing phase.

Among them, in the data writing stage, the second electrode of the fifth transistor T5 receives the data signal data, and the control electrode of the fifth transistor T5 generates a conduction signal under the action of the fourth scan signal scan4, so that the first electrode and the second electrode of the fifth transistor T5 are turned on, so that the data signal data can reach the first electrode of the fifth transistor T5 from the second electrode of the fifth transistor T5, that is, the second electrode of the driving transistor T0.

The storage capacitor C is used to store charges during the data writing phase, and the amount of the stored charges is positively correlated with the voltage of the data signal. The amount of charges stored in the storage capacitor C is the same as the amount of charges corresponding to the data signal.

The working state of the pixel driving circuit shown in FIG4 during the data writing stage is described below: the third initialization transistor T3, the driving transistor T0 and the fifth transistor are all turned on. The data signal data reaches the first electrode of the fifth transistor T5 (that is, the second electrode of the driving transistor T0) from the second electrode of the fifth transistor T5. At this moment, the driving transistor T0 is in a diode working state, so that the voltages of the first electrode and the second electrode of the driving transistor T0 are both the second target voltage, and the second target voltage is the voltage of the data signal data plus the threshold voltage of the driving transistor T0. Since the second end of the storage capacitor C is connected to the driving transistor T0, the data signal data can also be written into the storage capacitor C, so that the storage capacitor C can store the charge corresponding to the data signal.

The sixth transistor T6 responds to the turn-on signal in the light emitting stage, so that the driving transistor T0 generates a driving current under the effect of the stored charge and the power supply voltage ELVDD.

The second initialization transistor T2 responds to the turn-on signal in the light emitting stage so that the driving current generated by the driving transistor T0 is input to the anode of the light emitting device OLED.

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

The pixel driving circuit shown in FIG4 is described below with respect to the working state of the pixel driving circuit in the light-emitting stage: 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 can generate a driving current under the action of the charge released by the storage capacitor C and the power supply voltage ELVDD; when the second initialization transistor T2 is turned on, the driving current is input from the driving transistor T0 to the anode of the light-emitting device OLED.

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 can 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. Therefore, the transistors in the pixel driving circuit shown in FIG4 are all low-temperature polysilicon thin film transistors, which is conducive to improving the response efficiency of the entire circuit.

In some embodiments, the third initialization transistor T3 may be an oxide thin film transistor. The enabling mode of the oxide thin film transistor is low level off and high level on, and has the advantage of suppressing leakage. Therefore, in the pixel driving circuit shown in FIG4 , if the third initialization transistor T3 is an oxide thin film transistor, leakage of the pixel driving circuit can be effectively prevented.

Please refer to Figures 5A-5B, which are timing diagrams of the pixel driving circuit disclosed in the embodiment of the present application in the data refresh phase. Among them, the timing diagrams shown in Figures 5A-5B include a first initialization sub-phase t1, a first initialization sub-phase t2, a data writing phase t3, a light emitting initialization phase t4, and a light emitting phase t5. In the pixel driving circuit corresponding to Figure 5A, the third initialization transistor T3 is a low-temperature polysilicon thin film transistor. In the pixel driving circuit corresponding to Figure 5B, the third initialization transistor T3 is an oxide thin film transistor.

The working state of the pixel driving circuit shown in FIG. 4 in the data refresh phase is described below in conjunction with the timing diagram shown in FIG. 5A:

First initialization sub-phase t1: the second scanning signal scan2 and the third scanning signal scan3 are both at a low 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 t2: the first scanning signal scan1, the second scanning signal scan2 and the third scanning signal scan3 are all at low level, 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 writing stage t3: the third scanning signal scan3 and the fourth scanning signal scan4 are at a low level, so that the third initialization transistor T3, the driving transistor T0 and the fifth transistor T5 are all turned on.

Light emitting initialization stage t4: the first light emitting control signal EM1 and the first scanning signal scan1 are at a low level, so that the first initialization transistor T1 and the second initialization transistor T2 are turned on.

Light-emitting stage t5: the first light-emitting control signal EM1 and the second light-emitting control signal EM2 are at a level, so that the fifth transistor T5, the sixth transistor T6 and the driving transistor T0 are all turned on.

The working state of the pixel driving circuit shown in FIG. 4 in the data refresh phase is described below in conjunction with the timing diagram shown in FIG. 5B :

First initialization sub-phase t1: the second scanning signal scan2 is at a low level, and the third scanning 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 t2: the first scanning signal scan1 and the second scanning signal scan2 are at a low level, and the third scanning signal scan3 is at a high level, 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 writing stage t3: the third scanning signal scan3 is at a high level, and the fourth scanning 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.

Light emitting initialization stage t4: the first light emitting control signal EM1 and the first scanning signal scan1 are at a low level, so that the first initialization transistor T1 and the second initialization transistor T2 are turned on.

Light-emitting stage t5: the first light-emitting control signal EM1 and the second light-emitting control signal EM2 are at a level, so that the fifth transistor T5, the sixth transistor T6 and the driving transistor T0 are all turned on.

At present, the display mode of the display device may include a high-frequency display mode and a low-frequency display mode. Among them, the high-frequency display mode may refer to a display mode with a refresh rate greater than or equal to 120 Hz (Hertz). In the high-frequency display mode, each pixel updates the data signal no more than 0.0083 seconds, and the display device is continuously in the data refresh stage. The low-frequency display mode may refer to a display mode with a refresh rate less than 120 Hz. In the low-frequency display mode, each pixel updates the data signal more than 0.0083 seconds, and the display device is periodically in the data refresh stage and the data retention stage. Please refer to Figure 5C, which is a schematic diagram of an operating mode of a display device disclosed in an embodiment of the present application. The schematic diagram shown in Figure 5C includes a display mode with a refresh rate of 120 Hz, a display mode with a refresh rate of 60 Hz, and a display mode with a refresh rate of 40 Hz.

It should be noted that in the data holding stage, the driving transistor T0 does not receive the data signal Data, and maintains the driving current at this time to be the same as the driving current in the data refresh stage, so as to continuously drive the light-emitting device OLED to emit light stably. However, in the data holding stage, the voltage outside the driving transistor T0 will cause the output characteristic curve of the driving transistor T0 to drift, and accordingly, the brightness of the light-emitting device OLED will also change, which appears to the user as flickering, affecting the user's viewing experience.

To solve this problem, the fourth initialization transistor T4 initializes the second electrode of the driving transistor T0 in response to the fourth initialization voltage signal vint4 in the data holding stage, which can effectively compensate for the drift of the output characteristic of the driving transistor T0 and help alleviate the flicker phenomenon.

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

Please refer to Figures 5D-5E, wherein Figure 5D is a diagram showing the brightness change of the light emitting device OLED when the refresh rate is 40 Hz and the driving transistor T0 is not initialized. Figure 5E is a diagram showing the brightness change of the light emitting device OLED when the refresh rate is 40 Hz and the driving transistor T0 is initialized.

In some embodiments, the first initialization transistor T1 initializes the anode of the light-emitting device OLED in response to the second initialization voltage signal vint2 in the data holding stage, which can ensure the stability of the brightness of the light-emitting device in the data holding stage. It should be noted that the initialization process of the anode of the light-emitting device OLED by the first initialization transistor T1 in the data holding stage can be the same as the initialization process of the anode of the light-emitting device OLED by the first initialization transistor T1 in the light-emitting initialization stage, which will not be repeated here.

Please refer to Figure 5F, which is a timing diagram of the pixel driving circuit disclosed in the embodiment of the present application in the data holding stage. It should be noted that the pixel driving circuit shown in Figure 5F can be the same as the pixel driving circuit corresponding to Figure 5A/5B.

In conjunction with the timing diagram shown in FIG5F, the working state of the pixel driving circuit shown in FIG4 in the data holding stage is described below: the first light-emitting control signal EM1 and the second light-emitting control signal EM2 are both at a high level first, at which time the second scanning signal scan2 is at a low level, so that the fourth initialization transistor T4 is turned on to initialize the driving transistor T0. Then, the first light-emitting control signal EM1 changes to a low level before the second light-emitting control signal EM2, and at the same time, the first scanning signal scan1 is at a low level, so that the first initialization transistor T1 and the second initialization transistor T2 are both turned on to initialize the anode of the light-emitting device OLED. Finally, the first light-emitting control signal EM1 continues to maintain a low level, and the second light-emitting control signal EM2 also changes from a high level to a low level. At this time, the sixth transistor T6, the second initialization transistor T2 and the driving transistor T0 are all turned on to make the light-emitting device OLED emit light.

By implementing the pixel driving circuit shown in FIG4 , on the one hand, in the driving initialization stage, the first initialization transistor can also 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, effectively alleviating the problems of smearing and short residue of the display screen in the data refresh stage; in the light-emitting initialization stage, the anode of the light-emitting device is initialized by the first initialization transistor, which can improve the stability of the brightness of the light-emitting device in the data refresh stage. On the other hand, the initialization of the light-emitting device and the driving transistor is achieved by reusing the first initialization transistor, which can simplify the circuit. On the other hand, initializing each driving transistor in each row twice can effectively improve the defective state of the driving transistor T0, which is conducive to further alleviating the problems of smearing and short residue of the display screen in the data refresh stage. On the other hand, in the data retention stage, the anode of the driving transistor and the light-emitting device is initialized, which can effectively compensate for the drift of the output characteristics of the driving transistor, which is conducive to alleviating the flicker phenomenon.

The embodiment of the present application discloses a control method for a pixel driving circuit, wherein when the pixel driving circuit is in a driving initialization phase, a first initialization voltage signal is input to a first initialization transistor, so that the first initialization voltage signal is input to a first electrode of a driving transistor through the first initialization transistor, so as to initialize the first electrode of the driving transistor;

When the pixel driving circuit is in the light emitting initialization stage, a second initialization voltage signal is input to the first initialization transistor, 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 emitting initialization phase, a turn-on signal is input to the second initialization transistor, so that the second initialization voltage signal is transmitted from the first initialization transistor to the anode of the light emitting device.

In some embodiments, during the driving initialization stage, a conduction signal can also be input to the third initialization transistor to initialize the control electrode of the driving transistor, and a third initialization voltage signal can be input 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 driving 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 electrode of the driving transistor through the first initialization transistor.

In the first initialization sub-phase and the second initialization sub-phase, a turn-on signal is input to the third initialization transistor to initialize the control electrode of the driving transistor.

In the first initialization sub-phase and the second initialization sub-phase, the third initialization voltage signal is input to the fourth initialization transistor, so that the third initialization voltage signal is input to the second electrode of the driving transistor through the fourth initialization transistor.

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

In some embodiments, during the light-emitting stage, a conduction signal is input to the sixth transistor and the second initialization transistor respectively, so that the driving transistor generates a driving current under the action of the stored charge 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 stage, a second initialization voltage signal may be input to the first initialization transistor, and the second initialization voltage signal may be 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 input to the fourth initialization transistor, and the fourth initialization voltage signal may be transmitted to the second electrode of the driving transistor through the fourth initialization voltage signal.

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

An embodiment of the present application discloses a display screen, comprising the pixel driving circuit and a light-emitting device disclosed in the above embodiment, wherein the light-emitting device is connected to the pixel driving circuit, and is used to receive a driving current output by the pixel driving circuit, and emit light under the control of the driving current.

An embodiment of the present application discloses a display device, which includes the above-mentioned display screen.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

The above-described embodiments only express several implementation methods of the embodiments of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the embodiments of the present application, and these all belong to the protection scope of the embodiments of the present application. Therefore, the protection scope of the patent of the embodiments of the present application shall be subject to the attached claims.

Claims (9)

1. A pixel driving circuit, comprising: a first initialization transistor, wherein the first electrode of the first initialization transistor is respectively connected to the first electrode of the driving transistor and the anode of the light-emitting device, and the first electrode of the driving transistor is initialized in response to the first initialization voltage signal of the second initialization sub-stage of the driving initialization stage; and the anode of the light-emitting device is initialized in response to the second initialization voltage signal of the light-emitting initialization stage; wherein, in the driving initialization stage, the control electrode of the first initialization transistor generates a turn-on signal under the action of the first scanning signal, so that the first electrode and the second electrode of the first initialization transistor are turned on; wherein, the driving initialization stage includes a first initialization sub-stage and a second initialization sub-stage; The pixel driving circuit further includes: a second initialization transistor, wherein a first electrode of the second initialization transistor is respectively connected to the first electrode of the driving transistor and the first electrode of the first initialization transistor, and a second electrode of the second initialization transistor is connected to the anode of the light-emitting device, and in response to a turn-on signal in the light-emitting initialization stage, the second initialization voltage signal is transmitted from the first initialization transistor to the anode of the light-emitting device to initialize the anode of the light-emitting device; a third initialization transistor, wherein the first electrode of the third initialization transistor is connected to the control electrode of the driving transistor, the second electrode of the third initialization transistor is respectively connected to the first electrode of the driving transistor and the first electrode of the first initialization transistor, and the control electrode of the driving transistor is initialized in response to the conduction signal of the first initialization sub-stage and the second initialization sub-stage; the third initialization transistor is an oxide thin film transistor; wherein, in the driving initialization stage, the control electrode of the third initialization transistor generates a conduction signal under the control of the third scanning signal, so that the first electrode and the second electrode of the third initialization transistor are turned on; a fourth initialization transistor, wherein a first electrode of the fourth initialization transistor is connected to a second electrode of the driving transistor, and initializes the second electrode of the driving transistor in response to a third initialization voltage signal of the first initialization sub-stage and the second initialization sub-stage; wherein, in the driving initialization stage, a control electrode of the fourth initialization transistor generates a conduction signal under the action of a second scanning signal, so that the first electrode and the second electrode of the fourth initialization transistor are turned on; The timings of the first initialization voltage signal, the second initialization voltage signal and the third initialization voltage signal are not completely the same. 2. The pixel driving circuit according to claim 1, characterized in that the pixel driving circuit further comprises: a fifth transistor, wherein a first electrode of the fifth transistor is connected to a second electrode of the driving transistor, and writes a data signal into the second electrode of the driving transistor in response to a data writing signal in a data writing phase; the data writing phase is after the driving initialization phase; A storage capacitor, wherein the first end of the storage capacitor is used to obtain the power supply voltage, and the second end of the storage capacitor is respectively connected to the control electrode of the driving transistor and the first electrode of the third initialization transistor, and is used to store charge during the data writing stage, and the amount of stored charge is positively correlated with the voltage of the data signal. 3. The pixel driving circuit according to claim 2, characterized in that the pixel driving circuit further comprises: a sixth transistor, wherein a first electrode of the sixth transistor is used to obtain a power supply voltage and is connected to a first end of the storage capacitor, a second electrode of the sixth transistor is connected to a second electrode of the driving transistor, and in response to a turn-on signal in a light-emitting stage, the driving transistor generates a driving current under the action of the stored charge amount and the power supply voltage; wherein the light-emitting stage is after the data writing stage; The second initialization transistor, in response to a turn-on signal in the light emitting stage, enables the driving current generated by the driving transistor to be input to the anode of the light emitting device. 4 . The pixel driving circuit according to claim 1 , wherein the first initialization transistor initializes the anode of the light-emitting device in response to the second initialization voltage signal in a data holding phase. 5 . 5 . The pixel driving circuit according to claim 1 , wherein the fourth initialization transistor initializes the second electrode of the driving transistor in response to a fourth initialization voltage signal in a data holding phase. 6 . The pixel driving circuit according to claim 5 , wherein the fourth initialization voltage signal is 4V to 7V. 7. A control method for a pixel driving circuit, characterized in that it is applied to the pixel driving circuit, the method comprising: During the second initialization sub-stage of the driving initialization stage of the pixel driving circuit, a first initialization voltage signal is input to the first initialization transistor, so that the first initialization voltage signal is input to the first electrode of the driving transistor through the first initialization transistor; wherein the driving initialization stage includes the first initialization sub-stage and the second initialization sub-stage; When the pixel driving circuit is in a light emitting initialization stage, a second initialization voltage signal is input to the first initialization transistor, so that the second initialization voltage signal is input to the anode of the light emitting device through the first initialization transistor; wherein, in the driving initialization stage, the control electrode of the first initialization transistor generates a conduction signal under the action of the first scanning signal, so that the first electrode and the second electrode of the first initialization transistor are turned on; The pixel driving circuit further includes: a second initialization transistor, wherein a first electrode of the second initialization transistor is respectively connected to the first electrode of the driving transistor and the first electrode of the first initialization transistor, and a second electrode of the second initialization transistor is connected to the anode of the light-emitting device, and in response to a turn-on signal in the light-emitting initialization stage, the second initialization voltage signal is transmitted from the first initialization transistor to the anode of the light-emitting device to initialize the anode of the light-emitting device; a third initialization transistor, wherein the first electrode of the third initialization transistor is connected to the control electrode of the driving transistor, the second electrode of the third initialization transistor is respectively connected to the first electrode of the driving transistor and the first electrode of the first initialization transistor, and in the first initialization sub-stage and the second initialization sub-stage, a conduction signal is input to the third initialization transistor to initialize the control electrode of the driving transistor; the third initialization transistor is an oxide thin film transistor; wherein, in the driving initialization stage, the control electrode of the third initialization transistor generates a conduction signal under the control of a third scanning signal, so that the first electrode and the second electrode of the third initialization transistor are turned on; a fourth initialization transistor, wherein a first electrode of the fourth initialization transistor is connected to a second electrode of the driving transistor, and in the first initialization sub-stage and the second initialization sub-stage, a third initialization voltage signal is input to the fourth initialization transistor to initialize the second electrode of the driving transistor; wherein the control electrode of the fourth initialization transistor generates a conduction signal under the action of the second scanning signal to conduct the first electrode and the second electrode of the fourth initialization transistor; The timings of the first initialization voltage signal, the second initialization voltage signal and the third initialization voltage signal are not completely the same. 8. A display screen, comprising: The pixel driving circuit according to any one of claims 1 to 6; The light emitting device is connected to the pixel driving circuit, and is used to receive the driving current output by the pixel driving circuit and emit light under the control of the driving current. 9. A display device, characterized in that the display device comprises the display screen according to claim 8.