WO2023071677A1 - 像素驱动电路及其控制方法、显示屏和显示设备 - Google Patents

像素驱动电路及其控制方法、显示屏和显示设备 Download PDF

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Publication number
WO2023071677A1
WO2023071677A1 PCT/CN2022/121974 CN2022121974W WO2023071677A1 WO 2023071677 A1 WO2023071677 A1 WO 2023071677A1 CN 2022121974 W CN2022121974 W CN 2022121974W WO 2023071677 A1 WO2023071677 A1 WO 2023071677A1
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Prior art keywords
transistor
driving circuit
pole
pixel driving
phase
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PCT/CN2022/121974
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English (en)
French (fr)
Inventor
孔祥永
高延凯
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Oppo广东移动通信有限公司
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Publication of WO2023071677A1 publication Critical patent/WO2023071677A1/zh

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0243—Details of the generation of driving signals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen

Definitions

  • the present application relates to the field of display technology, in particular to a pixel driving circuit and a control method thereof, a display screen and a display device.
  • a pixel driving circuit and a control method thereof, a display screen and a display device are provided.
  • the drive transistor has a first pole and a second pole.
  • the drive transistor is used to receive a data signal during the data refresh phase and generate a drive current according to the data signal.
  • the second pole is used to receive the data signal during the data refresh phase and Outputting the driving current to the light emitting device in the data holding stage, so as to drive the light emitting device to emit light;
  • a low-frequency initialization transistor the first pole of the low-frequency initialization transistor is connected to the first pole of the driving transistor, and the second pole of the low-frequency initialization transistor is used to receive a third initialization signal during the data holding phase.
  • the initialization transistor is used to initialize the driving transistor according to the third initialization signal, so that the fluctuation value of the driving current in the data refreshing phase and the data holding phase is within a preset range.
  • a display comprising:
  • FIG. 1 is one of the circuit diagrams of a pixel driving circuit of an embodiment
  • FIG. 2 is a diagram of brightness changes in a low-frequency refresh cycle of a light-emitting device driven when the drive circuit is not provided with a low-frequency initialization transistor T8;
  • Fig. 3 is a diagram of brightness changes of a light-emitting device driven by a pixel driving circuit in one embodiment during a low-frequency refresh cycle;
  • FIG. 4 is the second circuit diagram of a pixel driving circuit in an embodiment
  • FIG. 5 is a third circuit diagram of a pixel driving circuit in an embodiment
  • FIG. 6 is a timing diagram of the pixel driving circuit in the embodiment of FIG. 5 in the data holding phase
  • FIG. 7 is a timing diagram of the pixel driving circuit in the embodiment of FIG. 5 in the data refresh phase
  • FIG. 8 is a fourth circuit diagram of a pixel driving circuit of an embodiment
  • FIG. 9 is a timing diagram of the pixel driving circuit in the embodiment of FIG. 8 in the data holding phase
  • FIG. 10 is a timing diagram of the pixel driving circuit in the embodiment of FIG. 8 in the data refresh phase.
  • first, second and the like used in this application may be used to describe various elements herein, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element.
  • the first scan signal Scan1 may be referred to as the second scan signal Scan2
  • the second scan signal Scan2 may be referred to as the first scan signal Scan1.
  • Both the first scan signal Scan1 and the second scan signal Scan2 are scan signals, but they are not the same scan signal.
  • first and second are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as “first” and “second” may explicitly or implicitly include at least one of these features.
  • plural means at least two, such as two, three, etc., unless otherwise specifically defined.
  • severeal means at least one, such as one, two, etc., unless otherwise specifically defined.
  • the pixel driving circuit in 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 target picture.
  • the display device may be a smart phone, a tablet computer, a game device, an augmented reality (Augmented Reality, AR) device, a notebook, a desktop computing device, a wearable device, and the like.
  • AR Augmented Reality
  • the following uses the mobile phone as an example for illustration.
  • Each light-emitting device in this embodiment can be, but not limited to, organic light-emitting diodes (Organic light-emitting diode, OLED), quantum dot light-emitting diodes (Quantum Dot Light Emitting Diodes, QLED) and micron-scale light-emitting diodes (Micro LED), sub millimeter light emitting diode (mini LED), etc.
  • OLED organic light-emitting diode
  • QLED Quantum Dot Light Emitting Diodes
  • Micro LED micron-scale light-emitting diodes
  • mini LED sub millimeter light emitting diode
  • the human eye will have the phenomenon of persistence of vision.
  • Persistence of vision refers to the phenomenon that when the human eye observes the scene, the light signal is transmitted to the brain, and the visual image does not disappear immediately after the effect of the light signal ends.
  • the duration of persistence of vision is specifically 0.1s-0.4s.
  • the refresh rate of the display device should be greater than the threshold frequency that can be captured by human eyes.
  • the threshold frequency is usually about 25fps, and correspondingly, the switching interval between two adjacent frames is about 0.04s.
  • the display device can be controlled to be in the high-frequency display mode to provide a smooth display screen; if the time interval between two adjacent frames of images that changes If the time interval is less than or equal to 0.04s, the display device may be controlled to be in a low-frequency display mode, so as to reduce power consumption of the display device.
  • the above switching interval threshold of 0.04s is only used for illustration. In other embodiments, the switching interval threshold may also be 0.03s, 0.035s, etc., which is not limited in this embodiment.
  • the processor in the display device can flexibly configure the display mode based on the above conditions, so as to achieve a balance between display quality and energy consumption.
  • the low-frequency display mode may be applied to an always-on screen display of a mobile phone, and the always-on screen display refers to displaying information such as current time and battery power when the mobile phone is in a standby state.
  • the mobile phone can be normally configured in a high-frequency display mode, and when conditions are met, the processor configures the mobile phone in a low-frequency display mode.
  • the low-frequency display mode can also be applied to wearable devices such as smart watches and smart bracelets. Users usually do not watch wearable devices for a long time. Therefore, wearable devices can be routinely configured as low-frequency display mode, and When the condition is met, the processor configures the wearable device to a high-frequency display mode.
  • the refresh rate in the high-frequency display mode can be understood as the highest refresh rate that the display device can support.
  • the display device may have a plurality of low-frequency display modes with different refresh rates, and may be configured as a low-frequency display mode corresponding to the refresh rate according to the conditions of the display screen. Therefore, in the embodiment of the present application, the display modes with a refresh rate lower than the highest refresh rate supported by the display device are collectively referred to as the low-frequency display mode, and no specific limitation is imposed on the refresh rate in the low-frequency display mode.
  • the pixel driving circuit is alternately in the data refreshing phase and the data holding phase in the low frequency display mode, and the pixel driving circuit is continuously in the data refreshing phase in the high frequency display mode.
  • FIG. 1 is one of circuit diagrams of a pixel driving circuit according to an embodiment.
  • the pixel driving circuit includes a driving transistor T1 and a low-frequency initialization transistor T8.
  • the embodiment of the present application also shows the light emitting device OLED connected to the pixel driving circuit, the anode of the light emitting device OLED is used to receive the driving current output by the pixel driving circuit, and the cathode of the light emitting device OLED is connected to the first power supply voltage terminal ELVSS connected, the voltage of the first power supply voltage terminal ELVSS can be, for example, 0V to -5V, and the light emitting device OLED is used to emit light under the drive of the driving current.
  • the control electrode of the drive transistor T1 is used to receive the data signal Data in the data refresh phase, and generate a drive current according to the data signal Data
  • the second pole of the drive transistor T1 is used to receive the data signal Data in the data refresh phase and the data hold phase
  • the driving current is output to the light emitting device OLED through the second pole of the driving transistor T1, so as to drive the light emitting device OLED to emit light.
  • the first electrode of the driving transistor T1 is connected to the second power supply voltage terminal ELVDD
  • the control electrode of the driving transistor T1 is used to receive the data signal Data, but it can be understood that in other embodiments , the driving transistor T1 can also be connected in other ways.
  • the low-frequency display mode has a data refresh phase and a data hold phase, and the data refresh phase and the data hold phase are two phases adjacent in time sequence.
  • the pixel drive circuit needs to drive the light-emitting device OLED to display the same brightness, and a low-frequency refresh cycle can be understood as a period when the image of the display device does not change.
  • the driving transistor T1 has a first pole and a second pole. In the data refresh phase, after receiving the data signal Data, the driving transistor T1 can generate a corresponding driving current according to the voltage of the data signal Data, and drive the light emitting device OLED to emit light.
  • the driving transistor T1 does not receive the data signal Data, and the driving current at this time should be kept the same as that in the data refreshing phase, so as to continuously drive the light emitting device OLED to emit light stably. Therefore, in the above two stages, the fluctuation value of the driving current needs to be kept within a preset range, so as to avoid the fluctuation of the driving current causing a large change in the brightness of the light-emitting device OLED.
  • the preset range is positively correlated with the displayed gray scale value, and the larger the gray scale value is, the larger the preset range is.
  • the grayscale value to be displayed currently is 32, the brightness change of about 0.05nit can be perceived by human eyes, and the preset range needs to be set to 0nit-0.05nit; if the grayscale value to be displayed currently is 223, the brightness change of about 1.38nit can be perceived by human eyes, and the preset range needs to be set to 0nit-1.38nit.
  • the output characteristic curve of the transistor determines the output current of the transistor, that is, the driving current of the driving transistor T1. Therefore, if the output characteristic curve of the driving transistor T1 drifts, the driving current output by the driving transistor T1 will also change, and correspondingly, the brightness of the light emitting device OLED will also change.
  • the above-mentioned changes are generally manifested as an increase in the drive current of the drive transistor T1 caused by leakage, that is, an increase in the brightness of the light-emitting device OLED as shown in FIG. 2 . brightness changes.
  • the light-emitting device OLED needs to provide 0nit brightness in two adjacent low-frequency refresh periods, but the brightness gradually rises to 1nit during the data retention phase of the first low-frequency refresh period, then the data refresh of the next low-frequency refresh period stage, the brightness will return to 0nit, and in the eyes of the user, flickering occurs, which affects the viewing experience of the user.
  • the first pole of the low-frequency initialization transistor T8 is connected to the first pole of the driving transistor T1, and the second pole of the low-frequency initialization transistor T8 is used to receive the third initialization during the data holding phase.
  • Signal Vinit3 the low-frequency initialization transistor T8 is used to initialize the drive transistor T1 according to the third initialization signal Vinit3, so that the fluctuation value of the drive current in the data refresh phase and the data hold phase is between within the preset range.
  • the voltage range of the third initialization signal Vinit3 is determined according to the voltage range of the data signal Data, and the voltage range of the third initialization signal Vinit3 may be, for example, 0V to 6.5V.
  • the low-frequency initialization transistor T8 can reset the driving transistor T1 during the data holding phase, so as to compensate for changes in the working state of the driving transistor T1 . That is, the drive transistor T1 is corrected to the state before the drift occurs, so as to restore the output characteristic curve of the drive transistor T1, so that the drive current output by the drive transistor T1 is the target drive current.
  • the target drive current refers to the value received during the data refresh phase The current corresponding to the data signal Data.
  • the voltage of the third initialization signal Vinit3 can be, for example, 5.6V, so as to adapt to the device performance of the driving transistor T1 and the voltage of the data signal Data, so as to realize the best compensation for the state drift of the driving transistor T1, thereby more The brightness variation of the light emitting device is reduced to a great extent.
  • the light-emitting device OLED in a low-frequency refresh cycle, can continuously provide the correct luminous brightness as shown in FIG. 3 , thereby improving the display stability of the display device in the low-frequency display state.
  • FIG. 4 is the second circuit diagram of a pixel driving circuit in an embodiment.
  • the data refresh phase includes a compensation writing sub-phase
  • the pixel driving circuit also includes a second transistor T2 and a storage Capacitor C1.
  • the first pole of the second transistor T2 is used to receive the data signal Data
  • the second pole of the second transistor T2 is connected to the first pole of the driving transistor T1
  • the second transistor T2 is used for
  • the compensation writing sub-phase is turned on to transmit the data signal Data to the first electrode of the driving transistor T1.
  • the control electrode of the second transistor T2 is used to receive the third scan signal Scan3, and the second transistor T2 is turned on and off under the control of the third scan signal Scan3.
  • the second transistor T2 as a P-type transistor as an example, when the signal of the third scanning signal Scan3 is at a low level, the second transistor T2 is turned on, and transmits the data signal Data to the first pole of the driving transistor T1; When the scan signal Scan3 is at low level, the second transistor T2 is turned off.
  • the on-off of the receiving path of the data signal Data can be flexibly controlled, thereby reducing the complexity when the external processor outputs the data signal Data.
  • the second transistor T2 can also isolate different pixel driving circuits, so as to suppress signal interference between different pixel driving circuits and improve the stability of the pixel driving circuits.
  • the storage capacitor C1 is respectively connected to the first power supply voltage terminal ELVDD and the control electrode of the driving transistor T1, the storage capacitor C1 is used to store charges in the compensation writing sub-phase, and the amount of stored charges is related to the data signal
  • the voltage of Data is positively correlated.
  • the data signal Data can be stored, so that the data signal Data line can transmit the data signal Data to different pixel driving circuits in time division, and the pixel driving circuit can transmit the data signal Data when the data signal Data is not received.
  • the driving transistor T1 is controlled to output a relatively stable driving current.
  • FIG. 5 is a third circuit diagram of a pixel driving circuit according to an embodiment.
  • the pixel driving circuit further includes a seventh transistor T7.
  • the first pole of the seventh transistor T7 is connected to the anode of the light emitting device OLED, the second pole of the seventh transistor T7 is used to receive the second initialization signal Vinit2 in the data holding phase, and the seventh transistor T7 T7 is used to initialize the anode of the light emitting device OLED according to the second initialization signal Vinit2.
  • the control electrode of the seventh transistor T7 is used to receive the second scan signal Scan2, and the seventh transistor T7 is used to transmit the second initialization signal Vinit2 to the anode of the light emitting device OLED under the control of the second scan signal Scan2 for initialization .
  • the second initialization signal Vinit2 can pull down the anode of the light-emitting device OLED to the second initialization voltage.
  • the second initialization voltage can be understood as the initial charging voltage of the anode of the light-emitting device OLED.
  • the second initialization voltage can be, for example, 0V to -5V. .
  • the charge stored in the parasitic capacitance of the light-emitting device OLED can be released, thereby ensuring the reliability of the luminance of the light-emitting device OLED during the data retention stage.
  • T4 is the initialization sub-phase of the data holding phase (abbreviated as the first initialization sub-phase)
  • T5 is the light-emitting sub-phase of the data holding phase.
  • stage abbreviated as the first light-emitting sub-stage
  • the pixel driving circuit can output a stable target driving current in the first light-emitting sub-stage.
  • the initialization operation is also controlled by the timing of the light emission control signal EM, that is, the initialization operation is performed only when the output path of the driving current controlled by the light emission control signal EM is disconnected, so that the initialization operation can be performed more flexibly and accurately. initialization.
  • the third initialization signal terminal does not need to be multiplexed to transmit other data signals, thereby avoiding the interference of other signals on the third initialization signal Vinit3, and selecting the initialization period more flexibly without being limited by the transmission period of other signals.
  • the time when the seventh transistor T7 initializes the anode of the light emitting device OLED corresponds to the time when the low-frequency initialization transistor T8 initializes the driving transistor T1 .
  • the time correspondence can be understood as that the seventh transistor T7 and the low-frequency initialization transistor T8 perform corresponding initialization operations at the same time.
  • the seventh transistor T7 controlled by the second scan signal Scan2 is turned on synchronously with the low-frequency initialization transistor T8 controlled by the fourth scan signal Scan4 . It can be understood that, if the scanning signals with the same time sequence are used, the generation logic of the scanning signals is relatively simple.
  • the seventh transistor T7 and the low-frequency initialization transistor T8 are turned on or off under the control of the same scanning signal, so as to realize the above-mentioned synchronous initialization function.
  • the display module may include a first gate control module, the first gate control module is respectively connected to the control electrode of the seventh transistor T7 and the control electrode of the low frequency initialization transistor T8, and the first gate control module is used to generate A scanning signal is transmitted to the seventh transistor T7 and the low-frequency initialization transistor T8 respectively, thereby simplifying the number of gate control modules in the display module.
  • the pixel driving circuit further includes a third transistor T3 .
  • the first pole of the third transistor T3 is connected to the second pole of the driving transistor T1
  • the second pole of the third transistor T3 is connected to the control pole of the driving transistor T1
  • the third transistor T3 uses In the compensation writing sub-phase, it is turned on to compensate the driving transistor T1.
  • the control electrode of the third transistor T3 is used for receiving the third scanning signal Scan3
  • the third transistor T3 is used for turning on and off under the control of the third scanning signal Scan3.
  • the amount of charge stored in the storage capacitor C1 is positively correlated with a voltage difference, and the voltage difference is the difference between the voltage of the data signal Data and the threshold voltage of the driving transistor T1 .
  • the third transistor T3 as a P-type transistor as an example, when the signal of the third scanning signal Scan3 is at a low level, threshold compensation is performed, and the storage capacitor C1 is charged, so that the compensation result is stored in the storage capacitor C1 .
  • the third transistor T3 may be a double-gate transistor.
  • the third transistor T3 with a double-gate transistor structure can effectively improve the reliability of threshold compensation, thereby improving the display quality of the display device. It can be understood that other transistors in the pixel driving circuit can also be double-gate transistors to further improve display quality.
  • the second pole of the seventh transistor T7 is also used to receive the second initialization signal Vinit2 in the compensation writing sub-phase, and the seventh transistor T7 is also used to receive the second initialization signal Vinit2 in the compensation writing sub-phase.
  • the anode of the light-emitting device OLED is initialized.
  • the second initialization signal Vinit2 can pull down the anode of the light-emitting device OLED to the second initialization voltage.
  • the second initialization voltage can be understood as the initial charging voltage of the anode of the light-emitting device OLED.
  • the second initialization voltage can be, for example, 0V to -5V. .
  • the charge stored in the parasitic capacitance of the light-emitting device OLED can be released, thereby ensuring the reliability of the luminance of the light-emitting device OLED in the data refresh phase.
  • FIG. 7 is a timing diagram of the pixel driving circuit in the embodiment of FIG. 5 in the data refresh phase.
  • the data refresh phase further includes an initialization sub-phase before the compensation writing sub-phase
  • T1 is the initialization sub-phase of the data refresh phase (abbreviated as the second initialization sub-phase)
  • T2 is the compensation writing sub-phase of the data refresh phase
  • T3 is the light-emitting sub-phase of the data refresh phase (abbreviated as the second light-emitting sub-phase) .
  • the pixel driving circuit further includes a fourth transistor T4, the first pole of the fourth transistor T4 is connected to the control pole of the driving transistor T1, and the second pole of the fourth transistor T4 is used for Receiving a first initialization signal Vinit1, the first initialization signal Vinit1 may be -3V to -5V, for example, the fourth transistor T4 is used to initialize the control electrode of the driving transistor T1 in the initialization sub-stage.
  • the control electrode of is used to receive the first scan signal Scan1
  • the fourth transistor T4 is used to be turned on and off under the control of the first scan signal Scan1.
  • the first initialization signal Vinit1 can pull down the gate voltage of the driving transistor T1 to the first initialization, and release the charge accumulated in the driving transistor T1 in the last low-frequency refresh period, thereby improving the accuracy of the driving current.
  • the data signal Data is written in the compensation write sub-stage, and the threshold voltage of the drive transistor T1 is compensated, so that accurate driving can be provided in the second light-emitting sub-stage current.
  • the fourth transistor T4 may be a double-gate transistor.
  • the fourth transistor T4 with a double-gate transistor structure can effectively improve the reliability of gate initialization, thereby improving the display quality of the display device.
  • the pixel driving circuit further includes a fifth transistor T5 and a sixth transistor T6 .
  • the first pole of the fifth transistor T5 is connected to the power supply voltage terminal, specifically connected to the first power supply voltage terminal ELVDD, the second pole of the fifth transistor T5 is connected to the first pole of the driving transistor T1, and the The second pole of the fifth transistor T5 is connected to the anode of the light-emitting device OLED, and the fifth transistor T5 is used to conduct in the light-emitting sub-phase, so that the driving transistor T1 can The charge and the voltage of the first supply voltage terminal ELVDD generate the driving current.
  • the fifth transistor T5 is used for controlling the on-off of the signal transmission path between the second power supply voltage terminal ELVSS and the first pole of the driving transistor T1 according to the light emission control signal EM.
  • the first pole of the sixth transistor T6 is connected to the second pole of the driving transistor T1, and the sixth transistor T6 is used to conduct in the light-emitting sub-phase, so that the driving transistor T1 outputs the driving current to the anode of the light emitting device OLED.
  • the control pole of the sixth transistor T6 is used to receive the light-emitting control signal EM, the first pole of the sixth transistor T6 is connected to the second pole of the driving transistor T1, the second pole of the sixth transistor T6 is connected to the anode of the light-emitting device OLED, and the sixth The transistor T6 is used for controlling the on-off of the signal transmission path between the second pole of the driving transistor T1 and the anode of the light-emitting device OLED according to the light-emitting control signal EM.
  • the fifth transistor T5 and the sixth transistor T6 are both P-type transistors as an example for illustration.
  • the fifth transistor T5 and the sixth transistor T6 are turned on to drive the transistor T1
  • the voltage of the first pole of the transistor is pulled up to the second power supply voltage ELVDD
  • the voltage of the second power supply voltage ELVDD can be 4.6V, for example, the gate-source voltage difference of the first driving transistor T1 changes, thereby generating the driving current and outputting the driving current to the light-emitting device OLED, thereby controlling the light-emitting device OLED to emit light.
  • Fig. 8 is the fourth circuit diagram of the pixel driving circuit of an embodiment
  • Fig. 9 is a timing diagram of the pixel driving circuit of the embodiment of Fig. 8 in the data holding phase
  • Fig. 10 is a timing diagram of the pixel driving circuit of the embodiment of Fig. timing diagram.
  • the transistor type of at least one of the third transistor T3 and the fourth transistor T4 is an oxide thin film transistor.
  • both the third transistor T3 and the fourth transistor T4 are oxide thin film transistors.
  • replacing the third transistor T3 and the fourth transistor T4 in FIG. 5 from a low-temperature polysilicon thin film transistor to an oxide thin film transistor can achieve the purpose of controlling leakage.
  • the driving capability of low temperature polysilicon thin film transistors is stronger than that of oxide thin film transistors. Therefore, in other embodiments, other switch transistors can also be set as oxide thin film transistors, and the driving transistor T1 can be kept as low temperature polysilicon thin film transistors. transistor to ensure the driving capability of the driving transistor T1.
  • the fourth transistor T4 is controlled by the first N-type scan signal NScan1
  • the third transistor T3 is controlled by the second N-type scan signal NScan2
  • the seventh transistor T7 is controlled by the first P-type scan signal PScan1.
  • the second transistor T2 is controlled by the second P-type scan signal PScan2, and the low-frequency initialization transistor T8 is controlled by the third P-type scan signal. It can be understood that the switching timings of the transistors in this embodiment are the same as those in the foregoing embodiments, and will not be repeated here.
  • the embodiment of the present application also provides a method for controlling a pixel driving circuit, which is used to control the above-mentioned pixel driving circuit.
  • the control method includes: configuring the pixel driving circuit in the data refresh phase, and outputting a data signal Data to The first pole of the transistor T1, the data signal Data is used to control the light-emitting brightness of the light-emitting device; the pixel driving circuit is configured to be in the data holding phase, and the third initialization signal Vinit3 is output to the first pole of the low-frequency initialization transistor T8, so that The low-frequency initialization transistor T8 initializes the driving transistor T1 according to the third initialization signal Vinit3.
  • the control method of this embodiment can make the pixel driving circuit output a stable driving current, thereby ensuring that the light emitting device has a stable luminous brightness in a low-frequency refresh cycle.
  • the embodiment of the present application also provides a display screen, including: the above-mentioned pixel driving circuit; a light emitting device connected to the pixel driving circuit for receiving the driving current output by the pixel driving circuit, Lights up under the control of electric current.
  • the display screen of this embodiment can have stable display brightness in the low-frequency display mode, thereby improving the user's viewing experience.
  • An embodiment of the present application also provides a display device, including: the above-mentioned display screen. Based on the aforementioned display screen, the display device of this embodiment can have stable display brightness in the low-frequency display mode, thereby improving the user's viewing experience.

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  • Computer Hardware Design (AREA)
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  • Electroluminescent Light Sources (AREA)

Abstract

一种像素驱动电路，其中所述像素驱动电路包括：驱动晶体管（T1），具有第一极、第二极，所述驱动晶体管（T1）用于在数据刷新阶段接收数据信号，并根据所述数据信号生成驱动电流，所述第二极用于在所述数据刷新阶段和数据保持阶段输出所述驱动电流至发光器件，以驱动所述发光器件发光；低频初始化晶体管（T8），所述低频初始化晶体管（T8）的第一极与所述驱动晶体管（T1）的第一极连接，所述低频初始化晶体管（T8）的第二极用于在所述数据保持阶段接收第三初始化信号，所述低频初始化晶体管（T8）用于根据所述第三初始化信号对所述驱动晶体管（T1）进行初始化，以使所述数据刷新阶段和所述数据保持阶段内所述驱动电流的波动值在预设范围内。

Description

像素驱动电路及其控制方法、显示屏和显示设备
相关申请的交叉引用
本申请要求于2021年10月27日提交中国专利局、申请号为2021112549700、发明名称为“像素驱动电路及其控制方法、显示屏和显示设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及显示技术领域，特别是涉及一种像素驱动电路及其控制方法、显示屏和显示设备。
背景技术
随着显示技术的不断发展，显示技术被陆续应用于各种移动终端中，例如手机、平板电脑和各种可穿戴设备等。移动终端的电池容量通常较小，因此，人们对移动终端设置了可变帧率模式，频率变化范围低至1Hz，高达140Hz，在低频显示模式下，数据保持阶段的时间较长，基于现有的OLED显示驱动电路，难以维持显示稳定性。
这里的陈述仅提供与本申请有关的背景信息，而不必然地构成示例性技术。
发明内容
根据本申请的各种实施例，提供一种像素驱动电路及其控制方法、显示屏和显示设备。
一种像素驱动电路，所述像素驱动电路包括：
驱动晶体管，具有第一极、第二极，所述驱动晶体管用于在数据刷新阶段接收数据信号，并根据所述数据信号生成驱动电流，所述第二极用于在所述数 据刷新阶段和数据保持阶段输出所述驱动电流至发光器件，以驱动所述发光器件发光；
低频初始化晶体管，所述低频初始化晶体管的第一极与所述驱动晶体管的第一极连接，所述低频初始化晶体管的第二极用于在所述数据保持阶段接收第三初始化信号，所述低频初始化晶体管用于根据所述第三初始化信号对所述驱动晶体管进行初始化，以使所述数据刷新阶段和所述数据保持阶段内所述驱动电流的波动值在预设范围内。
一种像素驱动电路的控制方法，用于控制如上述的像素驱动电路，所述控制方法包括：
配置所述像素驱动电路处于数据刷新阶段，并输出数据信号至驱动晶体管的第一极，所述数据信号用于控制发光器件的发光亮度；
配置所述像素驱动电路处于数据保持阶段，输出第三初始化信号至低频初始化晶体管的第一极，以使低频初始化晶体管根据所述第三初始化信号对所述驱动晶体管进行初始化。
一种显示屏，包括：
如上述的像素驱动电路；
发光器件，与所述像素驱动电路连接，用于接收所述像素驱动电路输出的驱动电流，并在所述驱动电流的控制下发光。
一种显示设备，所述显示设备包括如上述的显示屏。
本申请的一个或多个实施例的细节在下面的附图和描述中提出。本申请的其他特征、目的和优点将从说明书、附图以及权利要求书变得明显。
附图说明
为了更清楚地说明本申请实施例或示例性技术中的技术方案，下面将对实施例或示例性技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他实施例的附图。
图1为一实施例的像素驱动电路的电路图之一；
图2为驱动电路未设置低频初始化晶体管T8时驱动下的发光器件一个低频刷新周期中的亮度变化图；
图3为一实施例的像素驱动电路的驱动下的发光器件在一个低频刷新周期中的亮度变化图；
图4为一实施例的像素驱动电路的电路图之二；
图5为一实施例的像素驱动电路的电路图之三；
图6为图5实施例的像素驱动电路在数据保持阶段的时序图；
图7为图5实施例的像素驱动电路在数据刷新阶段的时序图；
图8为一实施例的像素驱动电路的电路图之四；
图9为图8实施例的像素驱动电路在数据保持阶段的时序图；
图10为图8实施例的像素驱动电路在数据刷新阶段的时序图。
具体实施方式
为了便于理解本申请实施例，下面将参照相关附图对本申请实施例进行更全面的描述。附图中给出了本申请实施例的首选实施例。但是，本申请实施例可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本申请实施例的公开内容更加透彻全面。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请实施例的技术领域的技术人员通常理解的含义相同。本文中在本申请实施例的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请实施例。本文所使用的术语“及/或”包括一个或多个相关的所列项目的任意的和所有的组合。
在本申请实施例的描述中，需要理解的是，术语“上”、“下”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方法或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
可以理解，本申请所使用的术语“第一”、“第二”等可在本文中用于描述各种元件，但这些元件不受这些术语限制。这些术语仅用于将第一个元件与另一个元件区分。举例来说，在不脱离本申请的范围的情况下，可以将第一扫描信号Scan1称为第二扫描信号Scan2，且类似地，可将第二扫描信号Scan2称为第一扫描信号Scan1。第一扫描信号Scan1和第二扫描信号Scan2两者都是扫描信号，但其不是同一扫描信号。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本申请的描述中，“多个”的含义是至少两个，例如两个，三个等，除非另有明确具体的限定。在本申请的描述中，“若干”的含义是至少一个，例如一个，两个等，除非另有明确具体的限定。
本申请实施例的像素驱动电路用于驱动显示设备中的发光器件发光，以使显示设备显示目标画面。显示设备可以为智能手机、平板电脑、游戏设备、增强现实(Augmented Reality，AR)设备、笔记本、桌面计算设备、可穿戴设备等。为了方便理解，下面以显示设备为手机进行举例说明。
本实施例中的各发光器件可以是但不限于有机发光二极管(Organic light-emitting diode，OLED)、量子点发光二极管(Quantum Dot Light Emitting Diodes，QLED)和微米级发光二极管(Micro LED)、亚毫米发光二极管(mini LED)等。需要说明的是，本申请各实施例均以发光器件为有机发光二极管OLED为例进行说明。显示设备具有低频显示模式和高频显示模式，低频显示模式下的刷新率小于高频显示模式下的刷新率。人眼会存在视觉暂留现象，视觉暂留是指人眼在观察景物时，光信号传入大脑，光信号的作用结束后，视觉形象并不立即消失的现象。视觉暂留的时长具体为0.1s-0.4s。进一步地，若相邻两帧图像的切换速度过慢时，这一切换过程也会被人眼捕捉到，并被感受为图像发生了闪烁。因此，显示设备的刷新率要大于能够被人眼捕捉到的阈值频率，该阈值频率通常为25fps左右，对应地，相邻两帧之间的切换间隔为0.04s左右。因此，若存在变化的相邻两帧图像之间的时间间隔大于0.04s，则可以控制显示设备处于高频显示模式，以提供流畅的显示画面；若 存在变化的相邻两帧图像之间的时间间隔小于或等于0.04s，则可以控制显示设备处于低频显示模式，以降低显示设备的功耗。需要说明的是，上述0.04s的切换间隔阈值仅用于举例说明，在其他实施例中，切换间隔阈值也可以为0.03s、0.035s等，本实施例不做限定。
显示设备中的处理器可以基于上述条件对显示模式进行灵活的配置，以实现显示质量与能耗之间的平衡。示例性地，低频显示模式可以应用于手机的息屏显示，息屏显示即是指在手机处于待机状态时，显示当前的时间、电量等信息。用户在使用手机时，通常会长时间观看，因此，手机可以常规配置为高频显示模式，并在满足条件时，处理器将手机配置为低频显示模式。另一示例性地，低频显示模式也可以应用于智能手表、智能手环等可穿戴设备，用户通常不会长时间观看可穿戴设备，因此，可穿戴设备可以常规配置为低频显示模式，并在满足条件时，处理器将可穿戴设备配置为高频显示模式。
其中，高频显示模式下的刷新率可以理解为显示设备能够支持的最高刷新率。进一步地，显示设备可以具有刷新率不同的多个低频显示模式，并可以根据显示画面的情况配置为对应刷新率的低频显示模式。因此，在本申请实施例中，将刷新率小于显示设备能够支持的最高刷新率的显示模式统称为低频显示模式，而不对低频显示模式下的刷新率做具体限定。而且，所述像素驱动电路在所述低频显示模式下交替处于所述数据刷新阶段和所述数据保持阶段，所述像素驱动电路在所述高频显示模式下持续处于所述数据刷新阶段。可以理解的是，当显示设备处于高频显示模式时，以刷新率为120Hz为例，每个像素需要每0.0083秒更新一次数据信号，若需要对高频显示模式再额外配置数据刷新阶段和数据保持阶段，就需要将0.0083秒再划分为两个阶段，而高频显示模式时刷新率已为显示设备能够支持的最高刷新率，即无法支持上述划分，因此，像素驱动电路在高频显示模式下持续处于所述数据刷新阶段。图1为一实施例的像素驱动电路的电路图之一，参考图1，所述像素驱动电路包括驱动晶体管T1和低频初始化晶体管T8。为了便于说明，本申请实施例还示出了与像素驱动电路连接的发光器件OLED，发光器件OLED的阳极用于接收像素驱动电路输出的驱动电流，发光器件OLED的阴极与第一电源电压端ELVSS连接，第一电源电压端ELVSS的电压例如可以为0V至-5V，发光器件OLED用于 在驱动电流的驱动下发光。其中，驱动晶体管T1的控制极用于在数据刷新阶段接收数据信号Data，根据所述数据信号Data生成驱动电流，所述驱动晶体管T1的第二极用于在所述数据刷新阶段和数据保持阶段经所述驱动晶体管T1的第二极输出所述驱动电流至发光器件OLED，以驱动所述发光器件OLED发光。在图1所示的实施例中，驱动晶体管T1的第一极与第二电源电压端ELVDD连接，驱动晶体管T1的控制极用于接收数据信号Data，但可以理解的是，在其他实施例中，驱动晶体管T1也可以采用其他连接方式。
其中，低频显示模式具有数据刷新阶段和数据保持阶段，数据刷新阶段和数据保持阶段为在时序上相邻的两个阶段。在一个低频刷新周期中，像素驱动电路需要驱动发光器件OLED显示相同的亮度，一个低频刷新周期可以理解为显示设备的图像不发生变化的一个时段。驱动晶体管T1具有第一极、第二极，在数据刷新阶段中，驱动晶体管T1接收数据信号Data后，可以根据数据信号Data的电压生成对应的驱动电流，并驱动发光器件OLED发光。在数据保持阶段中，驱动晶体管T1不接收数据信号Data，并应当保持此时的驱动电流与在数据刷新阶段时的驱动电流相同，以持续驱动发光器件OLED稳定发光。因此，在上述两个阶段中，驱动电流的波动值需要保持在预设范围内，以避免驱动电流的波动引发发光器件OLED的亮度大幅变化。
其中，上述预设范围与显示的灰阶值正相关，灰阶值越大，上述预设范围越大。示例性地，若当前需要显示的灰阶值为32，则0.05nit左右的亮度变化就能够被人眼察觉，需要将预设范围设置为0nit-0.05nit；若当前需要显示的灰阶值为223，则1.38nit左右的亮度变化才能够被人眼察觉，需要将预设范围设置为0nit-1.38nit。
但是，在数据保持阶段，驱动晶体管T1外部的电压会使晶体管的输出特性曲线发生漂移。当晶体管工作于饱和区时，输出特性曲线决定了晶体管的输出电流，即，驱动晶体管T1的驱动电流。因此，若驱动晶体管T1的输出特性曲线发生了漂移，则驱动晶体管T1输出的驱动电流也会发生变化，相应地，发光器件OLED的亮度也会发生变化。上述变化通常表现为漏电导致的驱动晶体管T1的驱动电流的上升，即，如图2所示的发光器件OLED的亮度上升，图2中示出了未设置低频初始化晶体管T8时一个低频刷新周期中的亮度变化 情况。示例性地，若发光器件OLED需要在相邻两个低频刷新周期均提供0nit的亮度，但在第一个低频刷新周期的数据保持阶段亮度逐渐上升至1nit，则下一个低频刷新周期的数据刷新阶段，亮度会重新恢复至0nit，在用户看来，即发生了闪烁现象，从而影响了用户的观看体验。
在本实施例中，所述低频初始化晶体管T8的第一极与所述驱动晶体管T1的第一极连接，所述低频初始化晶体管T8的第二极用于在所述数据保持阶段接收第三初始化信号Vinit3，所述低频初始化晶体管T8用于根据所述第三初始化信号Vinit3对所述驱动晶体管T1进行初始化，以使所述数据刷新阶段和所述数据保持阶段内所述驱动电流的波动值在预设范围内。其中，第三初始化信号Vinit3的电压范围根据数据信号Data的电压范围确定，第三初始化信号Vinit3的电压范围例如可以为0V至6.5V。具体地，低频初始化晶体管T8能够在数据保持阶段对驱动晶体管T1进行复位，以对驱动晶体管T1的工作状态的变化进行补偿。即，将驱动晶体管T1纠正至发生漂移前的状态，从而恢复驱动晶体管T1的输出特性曲线，使驱动晶体管T1输出的驱动电流为目标驱动电流，目标驱动电流即是指与数据刷新阶段接收到的数据信号Data相对应的电流。较为优选地，第三初始化信号Vinit3的电压例如可以为5.6V，从而适配于驱动晶体管T1的器件性能和数据信号Data的电压，以实现对驱动晶体管T1的状态漂移实现最佳补偿，从而更大程度上地减小发光器件的亮度变化。基于上述像素驱动电路，在一个低频刷新周期中，发光器件OLED能够持续提供如图3所示的正确的发光亮度，从而提高显示设备在低频显示状态下的显示稳定性。
图4为一实施例的像素驱动电路的电路图之二，参考图4，在本实施例中，所述数据刷新阶段包括补偿写入子阶段，所述像素驱动电路还包括第二晶体管T2和存储电容C1。
所述第二晶体管T2的第一极用于接收所述数据信号Data，所述第二晶体管T2的第二极与所述驱动晶体管T1的第一极连接，所述第二晶体管T2用于在所述补偿写入子阶段导通，以传输所述数据信号Data至所述驱动晶体管T1的第一极。具体地，第二晶体管T2的控制极用于接收第三扫描信号Scan3，第二晶体管T2在第三扫描信号Scan3的控制下导通和断开。以第二晶体管T2 为P型晶体管为例，当第三扫描信号Scan3的信号为低电平时，第二晶体管T2导通，并将数据信号Data传输至驱动晶体管T1的第一极；当第三扫描信号Scan3的信号为低电平时，第二晶体管T2断开。通过设置第二晶体管T2，可以灵活控制数据信号Data的接收路径的通断，从而减小外部处理器输出数据信号Data时的复杂度。而且，第二晶体管T2还能够隔离不同的像素驱动电路，以抑制不同像素驱动电路之间的信号干扰，提高像素驱动电路的稳定性。
存储电容C1分别与第一电源电压端ELVDD、所述驱动晶体管T1的控制极连接，所述存储电容C1用于在所述补偿写入子阶段存储电荷，且存储的电荷量与所述数据信号Data的电压正相关。具体地，通过设置存储电容C1，可以对数据信号Data进行存储，以使数据信号Data线能够分时向不同的像素驱动电路传输数据信号Data，像素驱动电路能够在未接收到数据信号Data时，根据存储电容C1中存储的电荷，控制驱动晶体管T1输出较为稳定的驱动电流。
图5为一实施例的像素驱动电路的电路图之三，参考图5，在本实施例中，所述像素驱动电路还包括第七晶体管T7。所述第七晶体管T7的第一极与所述发光器件OLED的阳极连接，所述第七晶体管T7的第二极用于在所述数据保持阶段接收第二初始化信号Vinit2，所述第七晶体管T7用于根据所述第二初始化信号Vinit2对所述发光器件OLED的阳极进行初始化。具体地，第七晶体管T7的控制极用于接收第二扫描信号Scan2，第七晶体管T7用于在第二扫描信号Scan2的控制下传输第二初始化信号Vinit2至发光器件OLED的阳极，以进行初始化。具体地，第二初始化信号Vinit2能够拉低发光器件OLED的阳极至第二初始化电压，第二初始化电压可理解为发光器件OLED的阳极起始充电电压，第二初始化电压例如可以为0V至-5V。在本实施例中，通过对发光器件OLED的阳极进行初始化，可以释放发光器件OLED的寄生电容中存储的电荷，从而确保数据保持阶段发光器件OLED的发光亮度的可靠性。
图6为图5实施例的像素驱动电路在数据保持阶段的时序图，参考图6，T4为数据保持阶段的初始化子阶段(简称为第一初始化子阶段)，T5为数据保持阶段的发光子阶段(简称为第一发光子阶段)，在第一初始化子阶段完成对驱动晶体管T1和发光器件OLED的初始化后，像素驱动电路能够在第一发 光子阶段输出稳定的目标驱动电流。而且，在本实施例中，初始化操作还受控于发光控制信号EM的时序，即，只有在发光控制信号EM控制驱动电流的输出路径断开时，才进行初始化操作，从而可以进行更加灵活准确的初始化。此外，第三初始化信号端无需复用以传输其他数据信号，从而可以避免其他信号对第三初始化信号Vinit3的干扰，也可以更加灵活地选择初始化时段，而不必受限于其他信号的传输周期。
继续参考图6，在其中一个实施例中，所述第七晶体管T7对所述发光器件OLED的阳极进行初始化的时间与所述低频初始化晶体管T8对所述驱动晶体管T1进行初始化的时间相对应。其中，时间相对应可以理解为第七晶体管T7和低频初始化晶体管T8在相同的时刻进行对应的初始化操作。具体地，第二扫描信号Scan2控制下的第七晶体管T7，与第四扫描信号Scan4控制下的低频初始化晶体管T8同步导通。可以理解的是，若采用时序相同的扫描信号，扫描信号的生成逻辑较为简单。
进一步地，所述第七晶体管T7和所述低频初始化晶体管T8在同一扫描信号的控制下导通或断开，以实现上述同步初始化的功能。再进一步地，显示模组可以包括第一栅极控制模块，第一栅极控制模块分别与第七晶体管T7的控制极、低频初始化晶体管T8的控制极连接，第一栅极控制模块用于生成一个扫描信号，并分别传输至第七晶体管T7和低频初始化晶体管T8，从而简化显示模组中的栅极控制模块的数量。
继续参考图5，在其中一个实施例中，像素驱动电路还包括第三晶体管T3。所述第三晶体管T3的第一极与所述驱动晶体管T1的第二极连接，所述第三晶体管T3的第二极与所述驱动晶体管T1的控制极连接，所述第三晶体管T3用于在所述补偿写入子阶段导通，以对所述驱动晶体管T1进行补偿。具体地，第三晶体管T3的控制极用于接收第三扫描信号Scan3，第三晶体管T3用于在第三扫描信号Scan3的控制下导通和断开。其中，所述存储电容C1存储的电荷量与电压差值正相关，所述电压差值为所述数据信号Data的电压与所述驱动晶体管T1的阈值电压之间的差值。具体地，以第三晶体管T3为P型晶体管为例，当第三扫描信号Scan3的信号为低电平时，进行阈值补偿，并对存储电容C1进行充电，从而将补偿结果存储在存储电容C1中。
可选地，如图5所示，第三晶体管T3可以为双栅极晶体管。在本实施例中，采用双栅极晶体管结构的第三晶体管T3，可以有效改善阈值补偿的可靠性，从而改善显示设备的显示质量。可以理解的是，像素驱动电路中的其他晶体管也可以为双栅极晶体管，以进一步提升显示质量。
在其中一个实施例中，所述第七晶体管T7的第二极还用于在所述补偿写入子阶段接收所述第二初始化信号Vinit2，所述第七晶体管T7还用于在所述补偿写入子阶段对所述发光器件OLED的阳极进行初始化。具体地，第二初始化信号Vinit2能够拉低发光器件OLED的阳极至第二初始化电压，第二初始化电压可理解为发光器件OLED的阳极起始充电电压，第二初始化电压例如可以为0V至-5V。在本实施例中，通过对发光器件OLED的阳极进行初始化，可以释放发光器件OLED的寄生电容中存储的电荷，从而确保数据刷新阶段发光器件OLED的发光亮度的可靠性。
图7为图5实施例的像素驱动电路在数据刷新阶段的时序图，参考图7，在其中一个实施例中，所述数据刷新阶段还包括位于所述补偿写入子阶段前的初始化子阶段，T1为数据刷新阶段的初始化子阶段(简称为第二初始化子阶段)，T2为数据刷新阶段的补偿写入子阶段，T3为数据刷新阶段的发光子阶段(简称为第二发光子阶段)。
继续参考图5，所述像素驱动电路还包括第四晶体管T4，所述第四晶体管T4的第一极与所述驱动晶体管T1的控制极连接，所述第四晶体管T4的第二极用于接收第一初始化信号Vinit1，第一初始化信号Vinit1例如可以为-3V至-5V，所述第四晶体管T4用于在所述初始化子阶段对所述驱动晶体管T1的控制极进行初始化。具体地，的控制极用于接收第一扫描信号Scan1，第四晶体管T4用于在第一扫描信号Scan1的控制下导通和断开。第一初始化信号Vinit1能够拉低驱动晶体管T1的控制极电压至第一初始化，释放驱动晶体管T1在上一低频刷新周期中累积的电荷，从而提高驱动电流的准确性。在第二初始化子阶段完成对驱动晶体管T1的初始化后，在补偿写入子阶段写入数据信号Data、并对驱动晶体管T1的阈值电压进行补偿，从而可以在第二发光子阶段提供准确的驱动电流。可选地，第四晶体管T4可以为双栅极晶体管。在本实施例中，采用双栅极晶体管结构的第四晶体管T4，可以有效改善栅极初 始化的可靠性，从而改善显示设备的显示质量。
继续参考图5，在其中一个实施例中，所述像素驱动电路还包括第五晶体管T5和第六晶体管T6。
所述第五晶体管T5的第一极与电源电压端连接，具体与第一电源电压端ELVDD连接，所述第五晶体管T5的第二极与所述驱动晶体管T1的第一极连接，所述第五晶体管T5的第二极与所述发光器件OLED的阳极连接，所述第五晶体管T5用于在所述发光子阶段导通，以使所述驱动晶体管T1根据所述存储电容C1存储的电荷和所述第一电源电压端ELVDD的电压生成所述驱动电流。第五晶体管T5用于根据发光控制信号EM控制第二电源电压端ELVSS和驱动晶体管T1的第一极之间的信号传输路径的通断。所述第六晶体管T6的第一极与所述驱动晶体管T1的第二极连接，所述第六晶体管T6用于在所述发光子阶段导通，以使所述驱动晶体管T1输出所述驱动电流至所述发光器件OLED的阳极。第六晶体管T6的控制极用于接收发光控制信号EM，第六晶体管T6的第一极与驱动晶体管T1的第二极连接，第六晶体管T6的第二极发光器件OLED的阳极连接，第六晶体管T6用于根据发光控制信号EM控制驱动晶体管T1的第二极和发光器件OLED的阳极之间的信号传输路径的通断。示例性地，以第五晶体管T5和第六晶体管T6均为P型晶体管为例进行说明，当发光控制信号EM为低电平时，第五晶体管T5和第六晶体管T6导通，将驱动晶体管T1的第一极的电压上拉至第二电源电压ELVDD，第二电源电压ELVDD的电压例如可以为4.6V，第一驱动晶体管T1的栅源电压差发生变化，从而生成驱动电流并将驱动电流输出至发光器件OLED，从而控制发光器件OLED发光。
图8为一实施例的像素驱动电路的电路图之四，图9为图8实施例的像素驱动电路在数据保持阶段的时序图，图10为图8实施例的像素驱动电路在数据刷新阶段的时序图。参考图8，第三晶体管T3和第四晶体管T4中的至少一个的晶体管类型为氧化物薄膜晶体管，在图8所示的实施例中，第三晶体管T3和第四晶体管T4均为氧化物薄膜晶体管，但在其他实施例中，也可以只有第三晶体管T3和第四晶体管T4中的一个为氧化物薄膜晶体管。氧化物薄膜晶体管具有更好的抑制漏电的性能。即，将图5中的第三晶体管T3和第 四晶体管T4从低温多晶硅薄膜晶体管更换为氧化物薄膜晶体管，能够达到控制漏电的目的。但可以理解的是，低温多晶硅薄膜晶体管的驱动能力强于氧化物薄膜晶体管，因此，在其他实施例中，也可以将其他开关晶体管设置为氧化物薄膜晶体管，并保持驱动晶体管T1为低温多晶硅薄膜晶体管，以确保驱动晶体管T1的驱动能力。
结合参考图9和图10，当第三晶体管T3和第四晶体管T4为氧化物薄膜晶体管时，需要调整第三晶体管T3和第四晶体管T4的扫描信号的使能方式，以确保第三晶体管T3和第四晶体管T4的正确通断。具体地，第三晶体管T3和第四晶体管T4均为高电平使能。因此，在本实施例中，第四晶体管T4受第一N型扫描信号NScan1控制，第三晶体管T3受第二N型扫描信号NScan2控制，第七晶体管T7受第一P型扫描信号PScan1控制，第二晶体管T2受第二P型扫描信号PScan2控制，低频初始化晶体管T8受第三P型扫描信号控制。可以理解的是，本实施例的各晶体管的开关时序与前述实施例相同，此处不再赘述。
本申请实施例还提供了一种像素驱动电路的控制方法，用于控制如上述的像素驱动电路，所述控制方法包括：配置所述像素驱动电路处于数据刷新阶段，并输出数据信号Data至驱动晶体管T1的第一极，所述数据信号Data用于控制发光器件的发光亮度；配置所述像素驱动电路处于数据保持阶段，输出第三初始化信号Vinit3至低频初始化晶体管T8的第一极，以使低频初始化晶体管T8根据所述第三初始化信号Vinit3对所述驱动晶体管T1进行初始化。基于前述像素驱动电路，本实施例的控制方法能够使像素驱动电路输出稳定的驱动电流，从而确保发光器件在一个低频刷新周期中具有稳定的发光亮度。
本申请实施例还提供了一种显示屏，包括：如上述的像素驱动电路；发光器件，与所述像素驱动电路连接，用于接收所述像素驱动电路输出的驱动电流，并在所述驱动电流的控制下发光。基于前述像素驱动电路，本实施例的显示屏能够在低频显示模式下具有稳定的显示亮度，从而提高用户的观看体验。
本申请实施例还提供了一种显示设备，包括：如上述的显示屏。基于前述显示屏，本实施例的显示设备能够在低频显示模式下具有稳定的显示亮度，从 而提高用户的观看体验。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本申请实施例的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请实施例构思的前提下，还可以做出若干变形和改进，这些都属于本申请实施例的保护范围。因此，本申请实施例专利的保护范围应以所附权利要求为准。

Claims (20)

  1. 一种像素驱动电路，其中所述像素驱动电路包括：
    驱动晶体管，具有第一极、第二极，所述驱动晶体管用于在数据刷新阶段接收数据信号，并根据所述数据信号生成驱动电流，所述第二极用于在所述数据刷新阶段和数据保持阶段输出所述驱动电流至发光器件，以驱动所述发光器件发光；
    低频初始化晶体管，所述低频初始化晶体管的第一极与所述驱动晶体管的第一极连接，所述低频初始化晶体管的第二极用于在所述数据保持阶段接收第三初始化信号，所述低频初始化晶体管用于根据所述第三初始化信号对所述驱动晶体管进行初始化，以使所述数据刷新阶段和所述数据保持阶段内所述驱动电流的波动值在预设范围内。
  2. 根据权利要求1所述的像素驱动电路，其中所述像素驱动电路还包括：
    第七晶体管，所述第七晶体管的第一极与所述发光器件的阳极连接，所述第七晶体管的第二极用于在所述数据保持阶段接收第二初始化信号，所述第七晶体管用于根据所述第二初始化信号对所述发光器件的阳极进行初始化。
  3. 根据权利要求2所述的像素驱动电路，其中在所述数据保持阶段，所述第七晶体管和所述低频初始化晶体管在同一扫描信号的控制下导通或断开。
  4. 根据权利要求2所述的像素驱动电路，其中所述数据刷新阶段包括补偿写入子阶段，所述像素驱动电路还包括：
    第二晶体管，所述第二晶体管的第一极用于接收所述数据信号，所述第二晶体管的第二极与所述驱动晶体管的第一极连接，所述第二晶体管用于在所述补偿写入子阶段导通，以传输所述数据信号至所述驱动晶体管的第一极；
    存储电容，分别与电源电压端、所述驱动晶体管的控制极连接，所述存储电容用于在所述补偿写入子阶段存储电荷，且存储的电荷量与所述数据信号的电压正相关。
  5. 根据权利要求4所述的像素驱动电路，其中还包括：
    第三晶体管，所述第三晶体管的第一极与所述驱动晶体管的第二极连接，所述第三晶体管的第二极与所述驱动晶体管的控制极连接，所述第三晶体管用于在所述补偿写入子阶段导通，以对所述驱动晶体管进行补偿；
    其中，所述存储电容存储的电荷量与电压差值正相关，所述电压差值为所述数据信号的电压与所述驱动晶体管的阈值电压之间的差值。
  6. 根据权利要求5所述的像素驱动电路，其中所述第三晶体管、所述第七晶体管和所述低频初始化晶体管中的至少一个的晶体管类型为氧化物薄膜晶体管。
  7. 根据权利要求5所述的像素驱动电路，其中所述第三晶体管为双栅极晶体管。
  8. 根据权利要求4所述的像素驱动电路，其中所述第七晶体管的第二极还用于在所述补偿写入子阶段接收所述第二初始化信号，所述第七晶体管还用于在所述补偿写入子阶段对所述发光器件的阳极进行初始化。
  9. 根据权利要求4所述的像素驱动电路，其中所述数据刷新阶段还包括位于所述补偿写入子阶段后的发光子阶段，所述像素驱动电路还包括：
    第五晶体管，所述第五晶体管的第一极与所述电源电压端连接，所述第五晶体管的第二极与所述驱动晶体管的第一极连接，所述第五晶体管用于在所述发光子阶段导通，以使所述驱动晶体管根据所述存储电容存储的电荷和所述电源电压端的电压生成所述驱动电流；
    第六晶体管，所述第六晶体管的第一极与所述驱动晶体管的第二极连接，所述第五晶体管的第二极与所述发光器件的阳极连接，所述第六晶体管用于在所述发光子阶段导通，以使所述驱动晶体管输出所述驱动电流至所述发光器件的阳极。
  10. 根据权利要求5所述的像素驱动电路，其中所述数据刷新阶段还包括位于所述补偿写入子阶段前的初始化子阶段，所述像素驱动电路还包括：
    第四晶体管，所述第四晶体管的第一极与所述驱动晶体管的控制极连接，所述第四晶体管的第二极用于接收第一初始化信号，所述第四晶体管用于在所述初始化子阶段对所述驱动晶体管的控制极进行初始化。
  11. 根据权利要求所述10所述的像素驱动电路，其中所述第三晶体管和所述第四晶体管均为氧化物薄膜晶体管。
  12. 根据权利要求所述11所述的像素驱动电路，其中所述第四晶体管受第一N型扫描信号控制，所述第三晶体管受第二N型扫描信号控制。
  13. 根据权利要求10所述的像素驱动电路，其中所述第一初始化信号的电压范围为3V至-5V。
  14. 根据权利要求2所述的像素驱动电路，其中所述第二初始化信号的电压范围为0V至-5V。
  15. 根据权利要求1至10任一项所述的像素驱动电路，其中所述像素驱动电路具有低频显示模式和高频显示模式，所述像素驱动电路在所述低频显示模式下交替处于所述数据刷新阶段和所述数据保持阶段，所述像素驱动电路在所述高频显示模式下持续处于所述数据刷新阶段。
  16. 根据权利要求1至10任一项所述的像素驱动电路，其中所述第三初始化信号的电压范围为0V至6.5V。
  17. 根据权利要求1至10任一项所述的像素驱动电路，其中所述第三初始化信号的电压为5.6V。
  18. 一种像素驱动电路的控制方法，用于控制如权利要求1至17任一项所述的像素驱动电路，所述控制方法包括：
    配置所述像素驱动电路处于数据刷新阶段，并输出数据信号至驱动晶体管的第一极，所述数据信号用于控制发光器件的发光亮度；
    配置所述像素驱动电路处于数据保持阶段，输出第三初始化信号至低频初始化晶体管的第一极，以使低频初始化晶体管根据所述第三初始化信号对所述驱动晶体管进行初始化。
  19. 一种显示屏，其中包括：
    如权利要求1至17任一项所述的像素驱动电路；
    发光器件，与所述像素驱动电路连接，用于接收所述像素驱动电路输出的驱动电流，并在所述驱动电流的控制下发光。
  20. 一种显示设备，其中所述显示设备包括如权利要求19所述的显示屏。
PCT/CN2022/121974 2021-10-27 2022-09-28 像素驱动电路及其控制方法、显示屏和显示设备 WO2023071677A1 (zh)

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