Pixel driving circuit and driving method thereof, display panel

Abstract

The application discloses a pixel driving circuit, a driving method thereof and a display panel. The pixel driving circuit comprises a data writing module, a coupling module, a comparison module, a first light-emitting control module, a current control module, a driving module, a second light-emitting control module and a light-emitting module. The data writing module is configured to write a pulse width modulation signal to a control end of the comparison module. The coupling module is configured to write a pulse width control voltage to control the on-time of the comparison module in a comparison stage. The comparison module is configured to write a conduction signal to the first light-emitting control module when turned on. The first light-emitting control module is configured to write a first power signal to a first end of the driving module. The second light-emitting control module is configured to turn on the connection between the driving module and the light-emitting module in the comparison stage. The pulse width control voltage is configured to comprise a first change stage of gradually changing from an initial potential to a set potential and a second change stage of gradually changing from the set potential to the initial potential. The application can achieve better gray scale division.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to display technology, and in particular, to a pixel driving circuit and a driving method thereof, and a display panel. BACKGROUND

[0002] With the development of display technology, display panels are applied more and more widely, and the requirements for display panels are also higher and higher.

[0003] The display panel realizes light-emitting display through a pixel driving circuit. The existing pixel driving circuit, such as a digital-analog hybrid driving circuit, has the problem of insufficient minimum gray scale, poor gray scale division, and serious influence on display effect. SUMMARY

[0004] The present application provides a pixel driving circuit and a driving method thereof, and a display panel to achieve better gray scale division effect.

[0005] In a first aspect, an embodiment of the present application provides a pixel driving circuit, comprising:

[0006] a data writing module, a coupling module, a comparison module, a first light-emitting control module, a current control module, a driving module, a second light-emitting control module, and a light-emitting module;

[0007] The data writing module is configured to write a pulse width modulation signal to a control end of the comparison module in a data writing stage; the coupling module is configured to write a pulse width control voltage to control the on-time of the comparison module in a comparison stage; the comparison module is configured to write an on signal to the first light-emitting control module when turned on; the first light-emitting control module is configured to write a first power signal to a first end of the driving module, and the current control module is configured to control the driving module to generate a driving current;

[0008] The second light-emitting control module is configured to turn on the connection between the driving module and the light-emitting module in the comparison stage; and the light-emitting module emits light in response to the driving current;

[0009] The pulse width control voltage is configured to include a first change stage of gradually changing from an initial potential to a set potential and a second change stage of gradually changing from the set potential to the initial potential.

[0010] Optionally, the pulse width control voltage is a triangular wave. The triangular wave can be more conveniently generated by a driving chip, which is conducive to reducing the power consumption of the driving chip.

[0011] Optionally, the duration of the first change stage is less than or equal to the duration of the second change stage. This can make the tailing phenomenon of the light-emitting module from dark state to bright state and from bright state to dark state weaker.

[0012] Optionally, the first change stage includes a first sub-stage before the comparison stage and a second sub-stage in the comparison stage.

[0013] The second change stage includes a third sub-stage in the comparison stage and a fourth sub-stage after the comparison stage. The time of the comparison module in the intermediate state between on and off is short, further weakening the tailing phenomenon.

[0014] Optionally, the first end of the data write-in module accesses the pulse width modulation signal, the control end of the data write-in module accesses the scan signal, and the second end of the data write-in module is electrically connected with the control end of the comparison module.

[0015] The first end of the coupling module accesses the pulse width control voltage, and the second end of the coupling module is electrically connected with the control end of the comparison module.

[0016] The first end of the comparison module accesses the second power supply signal, and the second end of the comparison module accesses the conduction signal.

[0017] The first end of the first light-emitting control module accesses the first power supply signal, the control end of the first light-emitting control module is electrically connected with the first end of the comparison module, and the second end of the first light-emitting control module is electrically connected with the first end of the driving module.

[0018] The control end of the driving module is electrically connected with the current control module, and the second end of the driving module is electrically connected with the first end of the second light-emitting control module.

[0019] The control end of the second light-emitting control module accesses the enable signal, the second end of the second light-emitting control module is electrically connected with the first end of the light-emitting module, and the second end of the light-emitting module accesses the third power supply signal.

[0020] Optionally, the pixel driving circuit further comprises:

[0021] The first end of the comparison module accesses the second power supply signal through the voltage limiting module. It can be ensured that the conduction signal can be fully written into the control end of the first light-emitting control module, and it can be ensured that the first light-emitting control module can be fully opened.

[0022] Optionally, the data write-in module comprises a first transistor, the first end of the first transistor serves as the first end of the data write-in module, the second end of the first transistor serves as the second end of the data write-in module, and the control end of the first transistor serves as the control end of the data write-in module.

[0023] The coupling module comprises a capacitor, a first end of the capacitor serving as a first end of the coupling module, and a second end of the capacitor serving as a second end of the coupling module.

[0024] The comparison module comprises a second transistor, a first end of the second transistor serving as a first end of the comparison module, a second end of the second transistor serving as a second end of the comparison module, and a control end of the second transistor serving as a control end of the comparison module.

[0025] The first light-emitting control module comprises a third transistor, a first end of the third transistor serving as a first end of the first light-emitting control module, a second end of the third transistor serving as a second end of the first light-emitting control module, and a control end of the third transistor serving as a control end of the first light-emitting control module.

[0026] The driving module comprises a fourth transistor, a first end of the fourth transistor serving as a first end of the driving module, a second end of the fourth transistor serving as a second end of the driving module, and a control end of the fourth transistor serving as a control end of the driving module.

[0027] The second light-emitting control module comprises a fifth transistor, a first end of the fifth transistor serving as a first end of the second light-emitting control module, a second end of the fifth transistor serving as a second end of the second light-emitting control module, and a control end of the fifth transistor serving as a control end of the second light-emitting control module.

[0028] Preferably, the pixel driving circuit further comprises a voltage limiting module, the voltage limiting module comprising a sixth transistor, a first end of the sixth transistor being connected to the second power supply signal, a control end of the sixth transistor being electrically connected to the first end of the sixth transistor, and a second end of the sixth transistor being electrically connected to the first end of the comparison module.

[0029] In a second aspect, an embodiment of the present application further provides a driving method of a pixel driving circuit, the pixel driving circuit comprising the pixel driving circuit of the first aspect, and the driving method of the pixel driving circuit comprising:

[0030] In the data writing stage, the pulse width modulation signal corresponding to the to-be-displayed gray scale is written into the control end of the comparison module through the data writing module.

[0031] In the comparison stage, the pulse width control voltage is coupled to the control end of the comparison module through the coupling module to control the conduction time of the comparison module.

[0032] Optionally, the first change stage comprises a first sub-stage located before the comparison stage and a second sub-stage located within the comparison stage.

[0033] Further comprising before the comparison stage:

[0034] A pre-writing stage, the coupling module couples the part of the pulse width control voltage in the first sub-stage to the control end of the comparison module;

[0035] The comparison stage is configured to couple the part of the pulse width control voltage in the second sub-stage to the control end of the comparison module through the coupling module.

[0036] In a third aspect, the embodiment of the present application further provides a display panel, which comprises the pixel driving circuit of the first aspect.

[0037] The technical scheme of the embodiment of the present application adopts the pixel driving circuit comprising a data writing module, a coupling module, a comparison module, a first light emitting control module, a current control module, a driving module, a second light emitting control module and a light emitting module; the data writing module is used for writing a pulse width modulation signal to the control end of the comparison module in a data writing stage; the coupling module is used for writing a pulse width control voltage to control the on time of the comparison module in a comparison stage; the comparison module is used for writing an on signal to the first light emitting control module when on; the first light emitting control module is used for writing a first power supply signal to the first end of the driving module; the current control module is used for controlling the driving module to generate a driving current; the second light emitting control module is used for turning on the connection between the driving module and the light emitting module in the comparison stage; the light emitting module emits light in response to the driving current; the pulse width control voltage is configured to comprise a first change stage of gradually changing from an initial potential to a set potential and a second change stage of gradually changing from the set potential to the initial potential. The comparison stage is divided into two stages, and the change in each stage is relatively fast, so that the potential change of the control end of the comparison module is also relatively fast, thereby the switching speed of the comparison module is relatively fast, the tailing phenomenon is greatly improved, and better gray scale division is achieved; at the same time, the leakage current of the current control module at the control end of the driving module is also relatively small, the stability of the driving current is greatly improved, and the effect of better gray scale division is further achieved. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A circuit structure schematic diagram of the pixel driving circuit provided by the embodiment of the present application;

[0039] Figure 2 A timing diagram of the pixel driving circuit provided by the embodiment of the present application;

[0040] Figure 3 Another timing diagram of the pixel driving circuit provided by the embodiment of the present application;

[0041] Figure 4 Another circuit structure schematic diagram of the pixel driving circuit provided by the embodiment of the present application;

[0042] Figure 5 A circuit structure diagram of a pixel driving circuit provided by an embodiment of the present application is shown in FIG. 1.

[0043] Figure 6 A flow chart of a driving method of a pixel driving circuit provided by an embodiment of the present application is shown in FIG. 2.

[0044] Figure 7 A structure diagram of a display panel provided by an embodiment of the present application is shown in FIG. 3. DETAILED DESCRIPTION

[0045] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that only the parts related to the present application are shown in the drawings for the convenience of description.

[0046] As mentioned in the background, the existing pixel driving circuit has the problems of insufficient darkness of the minimum gray scale and poor gray scale division effect. The applicant has found through careful research that the cause of the technical problem lies in that the transistor switching speed is slow in the existing pixel driving circuit based on digital-analog hybrid driving, thus the waveform tailing phenomenon exists, which further leads to the problems of insufficient darkness of the minimum gray scale and poor gray scale division effect.

[0047] In view of the above technical problems, the present application proposes the following solutions:

[0048] Figure 1 A circuit structure diagram of a pixel driving circuit provided by an embodiment of the present application is shown in FIG. 1. Figure 1 The pixel driving circuit comprises a data writing module 101, a coupling module 102, a comparison module 103, a first light-emitting control module 104, a current control module 105, a driving module 106, a second light-emitting control module 107 and a light-emitting module L. The data writing module 101 is configured to write a pulse width modulation signal SigPWM to a control end of the comparison module 103 in a data writing stage. The coupling module 102 is configured to write a pulse width control voltage Sweep to control the on-time of the comparison module 103 in a comparison stage. The comparison module 103 is configured to write a conduction signal VGL to the first light-emitting control module 104 when it is turned on. The first light-emitting control module 104 is configured to write a first power supply signal VDD1 to a first end of the driving module 106. The current control module 105 is configured to control the driving module 106 to generate a driving current. The second light-emitting control module 107 is configured to turn on the connection between the driving module 106 and the light-emitting module L in the comparison stage. The light-emitting module 107 emits light in response to the driving current. The pulse width control voltage Sweep is configured to comprise a first variation stage in which the voltage gradually changes from an initial voltage to a set voltage, and a second variation stage in which the voltage gradually changes from the set voltage to the initial voltage.

[0049] Specifically, the pixel driving circuit provided by the embodiment of the present application is based on a hybrid digital-analog driving architecture. The light emitting module L may be an OLED (Organic Light Emitting Diode) for example. The OLED is a current-mode device and emits light in response to a driving current to realize display. There are two ways for the light emitting module L to display a specific gray scale in response to the driving current. The first way is to change the driving current to display a specific gray scale. The second way is to keep the driving current unchanged, and the light emitting time corresponding to different gray scales is different within a frame time, so that the human eye perceives different gray scales. The pixel driving circuit of the embodiment adopts the second driving method, that is, the specific gray scale display is realized by controlling the light emitting time of the light emitting module L. The specific circuit structure of the current control module 105 is not limited, for example, a constant voltage may be generated to control the driving module 106 to generate a constant driving current when the light emitting module L emits light. The current control module 105 may be a current source for example. The driving process of the pixel driving circuit includes a data writing stage and a comparison stage. In the data writing stage, the data writing module 101 first writes the pulse width modulation signal SigPWM into the control end of the comparison module 103. The voltages of the pulse width modulation signals SigPWM corresponding to different gray scales are different, that is, the potential at the control end of the comparison module 103 written in the data writing stage is different when different gray scales are displayed, and at this time the comparison module 103 cannot be turned on, so that the gate signal cannot be written into the control end of the first light emitting control module 104, and the first light emitting control module 104 is also in an off state, and the light emitting module L cannot emit light. In the comparison stage, the pulse width control voltage Sweep starts to change. Due to the coupling effect of the coupling module 102, the potential at the control end of the comparison module 103 starts to change following the change of the pulse width control voltage Sweep. When the pulse width control voltage Sweep changes in the first change stage, the comparison module 103 changes from an off state to an on state at a certain moment, so as to control the comparison module 103 to be turned on, and then the gate signal VGL turns on the first light emitting control module 104, so that the current control module 105 can control the driving module 106 to generate a driving current, and then the light emitting module L emits light in response to the driving current. It should be noted that the pulse width control voltages Sweep corresponding to different gray scales are all the same, only the values of the pulse width modulation signals SigPWM corresponding to different gray scales are different. Therefore, the time required for the potential change (such as falling or rising) at the control end of the comparison module 103 to reach the potential at which the comparison module 103 is turned on is different in the comparison stage, and the time required for the potential of the comparison module 103 to change from on to off is also different in the comparison stage. Therefore, the values of the pulse width modulation signals SigPWM are different, so as to control the on time of the comparison module 103 to be different, that is, to control the light emitting time of the light emitting module L to be different.In the embodiment, the pulse width control voltage Sweep includes at least two change stages, i.e., a first change stage and a second change stage, the first change stage can make the comparison module 103 change from off to on, and the second change stage can make the comparison module 103 change from on to off. Since the comparison stage 103 is divided into two stages, the change in each stage is relatively fast, so that the potential change of the control end of the comparison module 103 is also relatively fast, thereby the switching speed of the comparison module 103 is relatively fast, which greatly improves the tailing phenomenon and realizes better gray scale division. Meanwhile, since the pulse width control voltage Sweep includes at least two change stages, the voltage difference between the initial potential and the set potential is not too large, and the pulse width control voltage Sweep is easier to be generated by the driving chip. In the embodiment, the data writing module 101, the coupling module 102, the comparison module 103 and the first light emitting control module 104 are equivalent to the PWM module, which can generate the PWM signal for controlling the light emitting time. The PWM module does not act on the control end of the driving module 106, while the current control module 105 (equivalent to the PAM module) acts on the control end of the driving module 106, i.e., the PWM module and the PAM module act on different positions of the driving module 106, thereby avoiding the case that the PAM module leaks through the PWM module to cause the instability of the driving current. That is, the embodiment can also improve the stability of the driving current, and further realize the effect of better gray scale division.

[0050] The technical scheme of the embodiment adopts a pixel driving circuit including a data writing module, a coupling module, a comparison module, a first light emitting control module, a current control module, a driving module, a second light emitting control module and a light emitting module. The data writing module is used for writing a pulse width modulation signal into the control end of the comparison module in a data writing stage. The coupling module is used for writing a pulse width control voltage to control the on time of the comparison module in a comparison stage. The comparison module is used for writing a driving signal into the first light emitting control module when on. The first light emitting control module is used for writing a first power signal into the first end of the driving module. The current control module is used for controlling the driving module to generate a driving current. The second light emitting control module is used for connecting the driving module and the light emitting module in the comparison stage. The light emitting module emits light in response to the driving current. The pulse width control voltage is configured to include a first change stage of gradually changing from an initial potential to a set potential and a second change stage of gradually changing from the set potential to the initial potential. The comparison stage is divided into two stages, and the change in each stage is relatively fast, so that the potential change of the control end of the comparison module is also relatively fast, thereby the switching speed of the comparison module is relatively fast, which greatly improves the tailing phenomenon and realizes better gray scale division. Meanwhile, the leakage current of the current control module at the control end of the driving module is relatively small, which greatly improves the stability of the driving current and further realizes the effect of better gray scale division.

[0051] Exemplarily, as shown in FIG. 1, Figure 1As shown, the first end of the data writing module 101 accesses the pulse width modulation signal SigPWM, the control end of the data writing module 101 accesses the scanning signal PWM, and the second end of the data writing module 101 is electrically connected with the control end of the comparison module 103; the first end of the coupling module 102 accesses the pulse width control voltage Sweep, and the second end of the coupling module 102 is electrically connected with the control end of the comparison module 103; the first end of the comparison module 103 accesses the second power supply signal VDD2, and the second end of the comparison module 103 accesses the gate-on signal VGL; the first end of the first light-emitting control module 104 accesses the first power supply signal VDD1, the control end of the first light-emitting control module 104 is electrically connected with the first end of the comparison module 103, the second end of the first light-emitting control module 104 is electrically connected with the first end of the driving module 106; the control end of the driving module 106 is electrically connected with the current control module 105, and the second end of the driving module 106 is electrically connected with the first end of the second light-emitting control module 107; the control end of the second light-emitting control module 107 accesses the enable signal EM, the second end of the second light-emitting control module 107 is electrically connected with the first end of the light-emitting module L, and the second end of the light-emitting module L accesses the third power supply signal VSS. Wherein, VDD2-VDD1≥Vth2 can be set, wherein Vth2 is the threshold voltage of the first light-emitting control module 104, so as to avoid the false turn-on of the first light-emitting control module 104.

[0052] Specifically, Figure 2 a timing diagram of the pixel driving circuit provided by the embodiment of the present application, Figure 2 and Figure 1 Correspondingly, the embodiment takes the case that each module is turned on when the control end is at a low level as an example, and of course, in some other embodiments, the module can also be turned on when the control end is at a high level; the driving process of the pixel driving circuit includes a data writing stage T1 and a comparison stage T2.

[0053] In the data writing stage T1, the scanning signal PWM is at a low level, and the enable signal EM is at a high level, so that the data writing module 101 is turned on, the pulse width modulation signal SigPWM is written to the control end of the comparison module 103, at this time, the control end potential of the comparison module 103 is Q1, at this time, the value of Q1 is SigPWM, and the difference SigPWM-VGL between the gate-on signal VGL and the pulse width modulation signal SigPWM is set to be greater than or equal to Vth3, wherein Vth3 is the threshold voltage of the comparison module 103, that is, the comparison module 103 is in an off state in the data writing stage;

[0054] During the comparison phase T2, the enable signal EM is low, the second light-emitting control module 107 is turned on, and the driving current generated by the driving module 106 can be transmitted to the light-emitting module L. That is, in this phase, as soon as the driving module 106 generates the driving current, the light-emitting module L can emit light. However, since the pulse width control voltage Sweep controls the on-time of the first light-emitting control module 104, it also controls the time when the driving module 106 generates the driving current. In this embodiment, the pulse width control voltage Sweep changes from the initial potential ( Figure 2 The maximum value of Sweep drops to the set potential ( Figure 2 The first change phase is defined as the minimum value of the Sweep voltage. The second change phase is the rise from the set potential to the initial potential. In the first change phase, the pulse width control voltage Sweep gradually decreases, causing the potential Q1 at the control terminal of the comparator module 103 to begin decreasing. When it drops to Q1 - VGL = Vth3, it continues to decrease, turning on the comparator module 103. This causes the turn-on signal VGL to be applied to the control terminal of the first light-emitting control module 104, turning it on. This, in turn, enables the drive module 106 to generate a drive current, allowing the light-emitting module L to emit light in response to the drive current. As the pulse width control voltage Sweep continues to decrease... The comparison module 103 remains on and continues to be on even when the voltage drops to the set potential. Subsequently, the pulse width control voltage Sweep begins to rise, causing the potential Q1 at the control terminal of the comparison module 103 to rise. When the potential Q1 rises to Q1-VGL=Vth3, the potential Q1 continues to rise and the comparison module 103 is turned off, thereby turning off the first light-emitting control module 104. The driving module 106 cannot generate driving current, and the light-emitting module L stops emitting light. Thus, the conduction time of the comparison module 103 is controlled by the pulse width control voltage Sweep. Furthermore, because the comparison module 103 switches quickly, the trailing phenomenon is greatly improved, and better grayscale division is achieved.

[0055] Optionally, such as Figure 2 As shown, the pulse width control voltage Sweep is a triangular wave.

[0056] Specifically, the pulse width control voltage Sweep is set as a triangular wave. In both the first and second change phases, the pulse width control voltage Sweep changes linearly, making it easier for the driver chip to generate this type of pulse width control voltage Sweep. In some other embodiments, the first change phase may also be in the form of a sine wave or other functions, and the second change phase may also be in the form of a sine wave or other functions.

[0057] Optionally, the duration of the first change stage is equal to the duration of the second change stage, which is configured to make the pulse width control voltage waveform in the form of a triangle wave into an isosceles triangle, i.e. the slopes of the first change stage and the second change stage are the same, which makes the speed of the comparison module 103 from off to on consistent with the speed from on to off, so that the trailing phenomenon of the light emitting module L from dark state to bright state and from bright state to dark state is weaker. Alternatively, the duration of the first change stage can also be set to be less than the duration of the second change stage, so that the slope of the first change stage is greater than the slope of the second change stage, and the time required for the comparison module 103 to turn from off to on is shorter. At this time, the enable signal EM is controlled to change from low to high to make the light emitting module L stop emitting light before the second change stage ends, more specifically, before the pulse width control voltage Sweep rises to a level that allows the comparison module 103 to turn off, so that the trailing phenomenon can be greatly reduced.

[0058] It should be noted that, continuing to refer to Figure 2 , the driving method of the pixel driving circuit further includes other row writing stages T3, the display panel includes a plurality of pixel driving circuits, and the pulse width modulation signal SigPWM is written to the pixel driving circuits in the other rows in the T3 stage. Finally, the pixel driving circuits in all rows enter the comparison stage together to realize simultaneous light emission.

[0059] Optionally, as shown in Figure 3 , Figure 3 is another timing diagram of the pixel driving circuit provided by the embodiment of the present application, Figure 3 which can correspond to Figure 1 , in combination with Figure 1 and Figure 3 , in the embodiment, the first change stage includes a first sub-stage before the comparison stage T2 and a second sub-stage in the comparison stage; and the second change stage includes a third sub-stage in the comparison stage and a fourth sub-stage after the comparison stage.

[0060] Specifically, in the embodiment, the pulse width control voltage Sweep does not start to change only in the comparison stage T2, but starts to change before the comparison stage T2, i.e. starts to change in the first sub-stage T3. This configuration can make the comparison module enter an intermediate state between the off state and the on state before the comparison stage T2, and the comparison module 103 is in the intermediate state between the off state and the on state for a shorter time in the comparison stage, thereby further reducing the trailing phenomenon. Similarly, the fourth sub-stage is configured to make the comparison module 103 in the intermediate state between the on state and the off state for a shorter time in the comparison stage T2, thereby further reducing the trailing phenomenon.

[0061] Optionally, Figure 4A circuit structure schematic diagram of another pixel driving circuit provided by the embodiment of the present application is shown in FIG. 6. Figure 4 The pixel driving circuit further comprises a voltage limiting module 108; the first end of the comparison module 103 is connected to the second power signal VDD2 through the voltage limiting module 108.

[0062] Specifically, the voltage limiting module 108 is used to prevent the case that when the comparison module 103 is turned on, the conduction signal VGL cannot be written into the control end of the first light emitting control module 104, so that the first light emitting control module 104 cannot be turned on; when the driving ability of the second power signal VDD2 is strong, if it is directly loaded to the control end of the first light emitting control module 104, the conduction signal VGL can not be written, the voltage limiting module 108 has a voltage limiting effect, which can prevent the second power signal VDD2 from being directly loaded to the control end of the first light emitting control module 104, and further can ensure that the conduction signal VGL can be fully written into the control end of the first light emitting control module 104, and ensure that the first light emitting control module 104 can be fully opened.

[0063] Exemplarily, Figure 5 A circuit structure schematic diagram of another pixel driving circuit provided by the embodiment of the present application is shown in FIG. 6. Figure 5The data writing module 101 includes a first transistor M1, a first end of the first transistor M1 serving as a first end of the data writing module 101, a second end of the first transistor M1 serving as a second end of the data writing module 101, and a control end of the first transistor M1 serving as a control end of the data writing module 101; the coupling module 102 includes a capacitor C1, a first end of the capacitor C1 serving as a first end of the coupling module 102, and a second end of the capacitor C1 serving as a second end of the coupling module 102; the comparison module 103 includes a second transistor M2, a first end of the second transistor M2 serving as a first end of the comparison module 103, a second end of the second transistor M2 serving as a second end of the comparison module 103, and a control end of the second transistor M2 serving as a control end of the comparison module 103; the first light-emitting control module 104 includes a third transistor M3, a first end of the third transistor M3 serving as a first end of the first light-emitting control module 104, a second end of the third transistor M3 serving as a second end of the first light-emitting control module 104, and a control end of the third transistor M3 serving as a control end of the first light-emitting control module 104; the driving module 106 includes a fourth transistor M4, a first end of the fourth transistor M4 serving as a first end of the driving module 106, a second end of the fourth transistor M4 serving as a second end of the driving module 106, and a control end of the fourth transistor M4 serving as a control end of the driving module 106; the second light-emitting control module 107 includes a fifth transistor M5, a first end of the fifth transistor M5 serving as a first end of the second light-emitting control module 107, a second end of the fifth transistor M5 serving as a second end of the second light-emitting control module 107, and a control end of the fifth transistor M5 serving as a control end of the second light-emitting control module 107. The voltage limiting module 108 includes a sixth transistor M6, a first end of the sixth transistor M6 being connected to a second power supply signal VDD2, the first end of the sixth transistor M6 being electrically connected to the control end of the sixth transistor M6, and a second end of the sixth transistor M6 being electrically connected to the first end of the second transistor M2. The sixth transistor M6 is in a diode connection mode, thereby achieving the voltage limiting function of the voltage limiting module 108; in the display panel, the transistor manufacturing process is relatively mature, and the diode with the voltage limiting function can be formed by using the diode connection mode of the transistor, which can greatly reduce the process cost of the display panel.

[0064] The first transistor M1 to the sixth transistor M6 can be P-type transistors, and in other embodiments, can be N-type transistors. Since the P-type transistor manufacturing process is more mature and the cost is lower in the field of display panels, the first transistor M1 to the sixth transistor M6 can be set as P-type transistors.

[0065] The embodiment of the present application also provides a driving method of the pixel driving circuit, Figure 6 The flow chart of the driving method of the pixel driving circuit provided by the embodiment of the present application is shown in Figure 6The pixel driving circuit is provided by any embodiment of the present application, and the driving method comprises the following steps:

[0066] In step S201, in the data writing stage, a pulse width modulation signal corresponding to a to-be-displayed gray scale is written into a control end of a comparison module by a data writing module;

[0067] In step S202, in the comparison stage, a pulse width control voltage is coupled to the control end of the comparison module by a coupling module to control the conduction time of the comparison module.

[0068] Specifically, the driving process of the pixel driving circuit comprises a data writing stage and a comparison stage. In the data writing stage, the data writing module 101 first writes the pulse width modulation signal SigPWM into the control end of the comparison module 103. Different gray scales correspond to different voltages of the pulse width modulation signal SigPWM, that is, different voltages of the potential written into the control end of the comparison module 103 when different gray scales are displayed. At this time, the comparison module 103 cannot be turned on, so that the gate signal VGL cannot be written into the control end of the first light-emitting control module 104, and the first light-emitting control module 104 is also in an off state, and the light-emitting module L cannot emit light. In the comparison stage, the pulse width control voltage Sweep starts to change. Due to the coupling effect of the coupling module 102, the potential of the control end of the comparison module 103 starts to change along with the change of the pulse width control voltage Sweep. When the pulse width control voltage Sweep changes in the first change stage, the comparison module 103 changes from an off state to an on state at a certain moment, thereby controlling the comparison module 103 to be turned on, so that the gate signal VGL turns on the first light-emitting control module 104, and then the current control module 105 can control the driving module 106 to generate a driving current, thereby causing the light-emitting module L to emit light in response to the driving current. In this embodiment, the pulse width control voltage Sweep comprises at least two change stages, i.e., the first change stage and the second change stage. The first change stage can make the comparison module 103 change from off to on, and the second change stage can make the comparison module 103 change from on to off. Since the comparison stage 103 is divided into two stages, the change in each stage is relatively fast, so that the potential change of the control end of the comparison module 103 is also relatively fast, thereby improving the switching speed of the comparison module 103, greatly improving the tailing phenomenon, and achieving better gray scale division.

[0069] The technical scheme of the embodiment adopts a driving method including: in a data writing stage, writing a pulse width modulation signal corresponding to a to-be-displayed gray scale into a control end of a comparison module through a data writing module; and in a comparison stage, coupling a pulse width control voltage to the control end of the comparison module through a coupling module to control a conduction time of the comparison module. The pulse width control voltage Sweep includes at least two change stages, i.e., a first change stage and a second change stage, the first change stage can make the comparison module 103 change from off to on, and the second change stage can make the comparison module 103 change from on to off. Since the comparison stage T1 is divided into two stages, the change in each stage is relatively fast, so that the potential change of the control end of the comparison module 103 is also relatively fast, thereby the switching speed of the comparison module 103 is relatively fast, and the tailing phenomenon is greatly improved, and better gray scale division is achieved.

[0070] Optionally, the first change stage includes a first sub-stage located before the comparison stage and a second sub-stage located in the comparison stage; and before the comparison stage, a pre-writing stage (i.e., the first sub-stage) is further included, in which the coupling module couples a part of the pulse width control voltage located in the first sub-stage to the control end of the comparison module; and the comparison stage is configured to couple, through the coupling module, a part of the pulse width control voltage located in the second sub-stage to the control end of the comparison module.

[0071] Specifically, the embodiment sets a pre-writing stage, and sets the first change stage to include a first sub-stage located before the comparison stage T1 and a second sub-stage located in the comparison stage. The pulse width control voltage Sweep does not start to change only in the comparison stage T2, but starts to change before the comparison stage T2, i.e., starts to change in the first sub-stage T3 (as shown in the figure), so that the comparison module enters an intermediate state between the off state and the on state before the comparison stage T2, and the comparison module 103 is in the intermediate state between the off state and the on state for a shorter time in the comparison stage, thereby further weakening the tailing phenomenon. Figure 3

[0072] The embodiment of the application further provides a display panel, Figure 7 A structural schematic diagram of a display panel provided by the embodiment of the application is shown in the figure, the display panel includes a plurality of pixel driving circuits PX arranged in a matrix form, and further includes scan lines (not shown) and data lines (not shown) staggered horizontally and vertically, which provide scan signals and pulse width modulation signals for the pixel driving circuits. Since the display panel includes the pixel driving circuit provided by any embodiment of the application, the display panel also has the same beneficial effects, which will not be described herein again.

[0073] ​Note that the above merely describes preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, modifications and substitutions can be made without departing from the scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A pixel driving circuit, characterized by comprising: The pixel driving circuit comprises: The data writing module, the coupling module, the comparison module, the first light-emitting control module, the current control module, the driving module, the second light-emitting control module and the light-emitting module; The data writing module is configured to write a pulse width modulation signal to a control terminal of the comparison module in a data writing stage; the coupling module is configured to write a pulse width control voltage to control the on time of the comparison module in a comparison stage; the comparison module is configured to write an on signal to the first light-emitting control module when turned on; the first light-emitting control module is configured to write a first power signal to a first terminal of the driving module, and the current control module is configured to control the driving module to generate a driving current; The second light-emitting control module is configured to turn on the connection between the driving module and the light-emitting module in the comparison stage; and the light-emitting module emits light in response to the driving current. The pulse width control voltage is configured to include a first change stage in which an initial potential gradually changes to a set potential and a second change stage in which the set potential gradually changes to the initial potential; and the duration of the first change stage is less than or equal to the duration of the second change stage.

2. The pixel driving circuit according to claim 1, characterized in that, The pulse width control voltage is a triangular wave.

3. The pixel driving circuit of claim 1, wherein, The first change stage includes a first sub-stage before the comparison stage and a second sub-stage in the comparison stage; The second change stage includes a third sub-stage in the comparison stage and a fourth sub-stage after the comparison stage.

4. The pixel driving circuit of claim 1, wherein, A first terminal of the data writing module is connected to the pulse width modulation signal, a control terminal of the data writing module is connected to a scan signal, and a second terminal of the data writing module is electrically connected to a control terminal of the comparison module; A first terminal of the coupling module is connected to the pulse width control voltage, and a second terminal of the coupling module is electrically connected to the control terminal of the comparison module; A first terminal of the comparison module is connected to a second power signal, and a second terminal of the comparison module is connected to the on signal; A first terminal of the first light-emitting control module is connected to the first power signal, a control terminal of the first light-emitting control module is electrically connected to the first terminal of the comparison module, and a second terminal of the first light-emitting control module is electrically connected to the first terminal of the driving module; A control terminal of the driving module is electrically connected to the current control module, and a second terminal of the driving module is electrically connected to a first terminal of the second light-emitting control module; A control terminal of the second light-emitting control module is connected to an enable signal, a second terminal of the second light-emitting control module is electrically connected to a first terminal of the light-emitting module, and a second terminal of the light-emitting module is connected to a third power signal.

5. The pixel driving circuit of claim 4, wherein, The pixel driving circuit further comprises: A voltage limiting module, and the first terminal of the comparison module is connected to the second power signal through the voltage limiting module.

6. The pixel driving circuit according to claim 4 or 5, characterized in that, The data writing module comprises a first transistor, a first terminal of the first transistor is a first terminal of the data writing module, a second terminal of the first transistor is a second terminal of the data writing module, and a control terminal of the first transistor is a control terminal of the data writing module; The coupling module comprises a capacitor, a first end of the capacitor serving as a first end of the coupling module, and a second end of the capacitor serving as a second end of the coupling module. The comparison module comprises a second transistor, a first end of the second transistor serving as a first end of the comparison module, a second end of the second transistor serving as a second end of the comparison module, and a control end of the second transistor serving as a control end of the comparison module. The first light-emitting control module comprises a third transistor, a first end of the third transistor serving as a first end of the first light-emitting control module, a second end of the third transistor serving as a second end of the first light-emitting control module, and a control end of the third transistor serving as a control end of the first light-emitting control module. The driving module comprises a fourth transistor, a first end of the fourth transistor serving as a first end of the driving module, a second end of the fourth transistor serving as a second end of the driving module, and a control end of the fourth transistor serving as a control end of the driving module. The second light-emitting control module comprises a fifth transistor, a first end of the fifth transistor serving as a first end of the second light-emitting control module, a second end of the fifth transistor serving as a second end of the second light-emitting control module, and a control end of the fifth transistor serving as a control end of the second light-emitting control module.

7. The pixel driving circuit of claim 6, wherein, The pixel driving circuit further comprises a voltage limiting module, the voltage limiting module comprising a sixth transistor, a first end of the sixth transistor being connected to the second power supply signal, a control end of the sixth transistor being electrically connected to the first end of the sixth transistor, and a second end of the sixth transistor being electrically connected to the first end of the comparison module.

8. A driving method of a pixel driving circuit, characterized by, The pixel driving circuit comprises any one of the pixel driving circuits according to claims 1-7, and a driving method of the pixel driving circuit comprises: In a data writing stage, a pulse width modulation signal corresponding to a to-be-displayed gray scale is written into the control end of the comparison module through the data writing module; In a comparison stage, the pulse width control voltage is coupled to the control end of the comparison module through the coupling module to control the conduction time of the comparison module.

9. The driving method of the pixel driving circuit according to claim 8, wherein The first change stage comprises a first sub-stage before the comparison stage and a second sub-stage in the comparison stage; Before the comparison stage, there is further: a pre-writing stage, in which the coupling module couples the part of the pulse width control voltage in the first sub-stage to the control end of the comparison module; The comparison stage is configured to couple the part of the pulse width control voltage in the second sub-stage to the control end of the comparison module through the coupling module.

10. A display panel, characterized by, The display panel comprises any one of the pixel driving circuits according to claims 1-7.

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