WO2020215884A1 - 像素驱动电路及其驱动方法、显示面板和显示装置 - Google Patents

像素驱动电路及其驱动方法、显示面板和显示装置 Download PDF

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Publication number
WO2020215884A1
WO2020215884A1 PCT/CN2020/076785 CN2020076785W WO2020215884A1 WO 2020215884 A1 WO2020215884 A1 WO 2020215884A1 CN 2020076785 W CN2020076785 W CN 2020076785W WO 2020215884 A1 WO2020215884 A1 WO 2020215884A1
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terminal
signal terminal
voltage signal
signal
node
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PCT/CN2020/076785
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English (en)
French (fr)
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成军
闫梁臣
王东方
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京东方科技集团股份有限公司
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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]
    • G09G3/3225—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] using an active matrix

Definitions

  • the present disclosure relates to the field of display technology, and more particularly to a pixel driving circuit and a driving method thereof, a display panel, and a display device.
  • TFT thin film transistor
  • a-Si amorphous silicon
  • LTPS current low temperature polysilicon
  • MILC metal induced lateral crystallization
  • LCD liquid crystal display
  • PDP plasma display panel
  • OLED organic light-emitting diode
  • OLED is a new generation of display devices. Compared with liquid crystal displays, OLED has many advantages, such as self-luminescence, fast response speed, and wide viewing angle. It can be used for flexible display, transparent display, 3D display, etc.
  • the active matrix organic light emitting display (AMOLED) is equipped with a switch for controlling the pixel, such as a thin film transistor, for each pixel. Therefore, through the driving circuit, each pixel can be independently controlled without causing crosstalk to other pixels.
  • Thin film transistors generally include at least a gate, a source and a drain, a gate insulating layer and an active layer.
  • the active layer of thin film transistors is mainly silicon, which can be amorphous silicon or polysilicon.
  • Thin film transistors that use amorphous silicon as the active layer are difficult to use in applications that require larger currents and fast response due to their characteristics (such as mobility, on-state current, etc.), such as organic light-emitting displays and large-size, high Displays with high resolution and high refresh rate.
  • thin film transistors using polysilicon as an active layer have better characteristics than amorphous silicon and can be used in organic light emitting displays.
  • due to its poor uniformity it is still difficult to prepare medium and large-sized panels.
  • oxide semiconductors have received increasing attention.
  • Thin film transistors with oxide semiconductors as active layers have better characteristics than amorphous silicon, such as mobility, on-state current, and switching characteristics. Although the characteristics are not as good as polysilicon, it is sufficient for applications that require fast response and larger current, such as high-frequency, high-resolution, large-size displays and organic light-emitting displays.
  • the uniformity of the oxide is better.
  • Compared with polysilicon since there is no uniformity problem, there is no need to increase the compensation circuit, and it has advantages in the number of masks and the difficulty of production. There is no difficulty in making large-size displays. Moreover, it can be prepared by sputtering and other methods without adding additional equipment, which has a cost advantage.
  • the oxide semiconductor material used in the oxide thin film transistor has good semiconductor characteristics when it has a high oxygen content, and has a lower resistivity when it has a low oxygen content, so it can be used as a transparent electrode.
  • an embodiment of the present disclosure provides a pixel driving circuit.
  • the pixel driving circuit includes a charge control sub-circuit, which is coupled to a scan signal terminal, a data signal terminal, and a first node, and is configured to be able to transmit to the first node under the control of a scan signal from the scan signal terminal The data signal from the data signal terminal; a signal storage sub-circuit, which is coupled to the first node and the organic light emitting diode "OLED" element, and is configured to be able to store the signal from the first node or to the first node A node transmits the stored signal; a first driving sub-circuit, which is coupled to the first node, the first voltage signal terminal and the OLED element, and is configured to be able to control the level of the first node Downwardly transmitting the first voltage signal from the first voltage signal terminal to the OLED element; and a second driving sub-circuit, which is coupled to the first node, the second voltage signal terminal and the OLED element, and is configured configured
  • the charge control sub-circuit includes: a first transistor, the control terminal of which is coupled to the scan signal terminal, the first terminal is coupled to the data signal terminal, and the second terminal is coupled to the first transistor.
  • the signal storage sub-circuit includes: a first capacitor, a first terminal of which is coupled to the first node, and a second terminal of which is coupled to the OLED element.
  • the first driving sub-circuit includes: a second transistor, the control terminal of which is coupled to the first node, the first terminal is coupled to the first voltage signal terminal, and the second terminal is coupled to the The OLED element is coupled.
  • the second driving sub-circuit includes: a third transistor, the control terminal of which is coupled to the first node, the first terminal is coupled to the second voltage signal terminal, and the second terminal is coupled to the The OLED element is coupled.
  • the pixel driving circuit further includes a sensing sub-circuit, which is coupled to a sensing scan signal terminal, the OLED element, and a sensing output signal terminal, and is configured to be Under the control of the sensing scan signal of the scan signal terminal, a driving signal for driving the OLED element is transmitted to the sensing output signal terminal as a sensing output signal.
  • the sensing sub-circuit includes: a fourth transistor, the control terminal of which is coupled to the sensing scan signal terminal, the first terminal is coupled to the OLED element, and the second terminal is coupled to the The sensing output signal terminal is coupled.
  • the pixel driving circuit further includes: one or more third driving sub-circuits, each of the third driving sub-circuits and the first node, the corresponding third voltage signal terminal and the The OLED element is coupled and configured to be able to transmit a third voltage signal from a corresponding third voltage signal terminal to the OLED element under the control of the level of the first node.
  • a display panel includes the aforementioned pixel driving circuit.
  • a display device including the above-mentioned display panel.
  • a method for driving the aforementioned pixel driving circuit includes the following operations: in the signal writing stage, a scan signal of an effective level is input to the scan signal terminal, a data signal is input to the data signal terminal, and the first voltage signal terminal and the second voltage signal terminal are respectively input invalid Level of the first voltage signal and the second voltage signal, and the pixel drive circuit outputs a low-level drive signal to the corresponding organic light-emitting diode "OLED" element; and in the light-emitting phase, the scan signal terminal inputs an invalid level Scanning signal, one of the first voltage signal terminal and the second voltage signal terminal inputs an effective level capable of driving the OLED element, the other inputs an inactive level or remains floating, and the pixel driving circuit outputs the same to the OLED element
  • the driving signal corresponding to the data signal drives the OLED to emit light in a corresponding gray scale.
  • the method further includes the following operations: in the sensing phase, a scan signal of an invalid level is input to the scan signal terminal, and a sensing scan signal of an effective level is input to the sensing scan signal terminal, One of the first voltage signal terminal and the second voltage signal terminal inputs an effective level capable of driving the OLED element, the other inputs an inactive level or remains floating, and the sensing signal output terminal outputs a drive corresponding to the data signal Signal, as the sensing output signal.
  • a method for driving the aforementioned pixel driving circuit includes the following operations: in the signal writing phase, the scan signal terminal inputs an effective level scan signal, the data signal terminal inputs a data signal, the first voltage signal terminal and the second voltage signal terminal, and the third The voltage signal terminal inputs the first voltage signal, the second voltage signal and the third voltage signal of an invalid level respectively, and the pixel driving circuit outputs the driving signal of the invalid level to the corresponding organic light emitting diode "OLED" element; and In the light-emitting stage, the scan signal terminal inputs an invalid level scan signal, the first voltage signal terminal, the second voltage signal terminal and one of the one or more third voltage signal terminals input an effective level capable of driving the OLED element, and other voltage signals The terminal inputs an invalid level or remains floating, and the pixel driving circuit outputs a driving signal corresponding to the data signal to the OLED element to drive the OLED element to emit light in a corresponding gray scale.
  • FIG. 1 is a schematic diagram showing an example specific configuration of a pixel driving circuit according to the related art.
  • FIG. 2 is a schematic diagram showing an example configuration of a pixel driving circuit according to an embodiment of the present disclosure.
  • FIG. 3 is a schematic diagram showing an example specific configuration of the pixel driving circuit shown in FIG. 2.
  • FIG. 4 is a timing chart showing an example operation of the pixel driving circuit shown in FIG. 3.
  • FIG. 5 is a schematic diagram showing an example configuration of a pixel driving circuit according to another embodiment of the present disclosure.
  • FIG. 6 is a schematic diagram showing an example specific configuration of the pixel driving circuit shown in FIG. 5.
  • FIG. 7 is a timing chart showing an example operation of the pixel driving circuit shown in FIG. 6.
  • FIG. 8 is a flowchart showing an example method for driving a pixel driving circuit according to an embodiment of the present disclosure.
  • the terms “including” and “containing” and their derivatives mean including but not limiting; the term “or” is inclusive, meaning and/or.
  • the orientation terms used such as “upper”, “lower”, “left”, “right”, etc., are used to indicate relative positional relationships to assist those skilled in the art to understand the present disclosure. Embodiments, and therefore those skilled in the art should understand: “up”/"down” in one direction can be changed to “down”/"up” in the opposite direction, and in the other direction, it may become other Position relationship, such as “left”/"right”, etc.
  • the embodiment of the present disclosure is applied to a pixel driving circuit of an OLED display device as an example for detailed description.
  • the application field of the present disclosure is not limited to this.
  • the pixel driving circuit and the like according to the embodiments of the present disclosure can be applied to other fields that need to use the pixel driving circuit, such as LCD display devices.
  • the transistor is described as an N-type transistor as an example in the following description, the present disclosure is not limited thereto.
  • the technical solution of the present application can also be implemented, and only the level setting and/or coupling are required. The connection relationship can be adjusted accordingly.
  • the level at which the corresponding transistor can be turned on is called the effective level
  • the level at which the corresponding transistor is turned off is called the inactive level.
  • the effective level is High level
  • invalid level is low level.
  • the transistor is a P-type transistor as an example, the effective level is high and low, and the invalid level is high.
  • FIG. 1 is a schematic diagram showing an example specific configuration of a pixel driving circuit 100 according to the related art.
  • the pixel driving circuit 100 includes a first transistor T1, a second transistor T2, a fourth transistor T4, and a first capacitor C1.
  • the control terminal of the first transistor T1 is coupled to the scan signal terminal G1, the first terminal is coupled to the data signal terminal DATA, and the second terminal is coupled to the first node N1.
  • the first transistor T1 can write the data signal from the data signal terminal DATA to the first node N1 under the control of the scan signal from the scan signal terminal G1.
  • the first capacitor C1 may be used to store the data signal written in the first node N1 and maintain the signal level of the first node N1 when the first transistor T1 is turned off.
  • the control terminal of the second transistor T2 is coupled to the first node N1, the first terminal is coupled to the first voltage signal terminal VDD, and the second terminal is coupled to the second node N2.
  • the second transistor T2 can provide a voltage/current signal from the voltage signal terminal VDD to the second node N2 (and then to the OLED element) under the control of the level of the first node N1 to drive the OLED element to work normally.
  • the control terminal of the fourth transistor T4 is coupled to the sensing scan signal terminal G2, the first terminal thereof is coupled to the second node N2, and the second terminal thereof is coupled to the sensing output signal terminal SENSE.
  • the fourth transistor T4 can output its sensed driving current through the second node N2 to the sensing output signal terminal SENSE under the control of the sensing scanning signal from the sensing scanning signal terminal G2, so that the sensing output is
  • the external compensation circuit coupled to the signal terminal SENSE can compensate the driving current of the subsequent frame according to the driving current, thereby avoiding or reducing the malfunction caused by the threshold drift of the second transistor T2 in the long-term on state. such. By adopting such a circuit structure, the OLED element can be driven.
  • the working time of the second transistor T2 increases during this process, its threshold voltage will drift. Especially if it is always in the on state and the current polarity is always the same, a unidirectional drift of the threshold voltage is more likely to occur, which in turn makes the OLED element appear darker or brighter.
  • defects such as afterimages, mura, and uneven brightness are displayed in different areas of the screen.
  • a pixel driving circuit and a driving method thereof, and a display panel and a display device including the pixel driving circuit according to embodiments of the present disclosure are proposed.
  • multiple driving transistors can be provided to reduce the driving time of a single driving transistor, thereby avoiding or reducing the threshold voltage drift of a single driving transistor, thereby improving the life of the pixel driving circuit, the display panel, and the display device.
  • the second driving transistor may be in a resting state when the first driving transistor is working, and the first driving transistor may be in a resting state when the second driving transistor is working.
  • FIG. 2 is a schematic diagram showing an example configuration of a pixel driving circuit 200 according to an embodiment of the present disclosure.
  • the pixel driving circuit 200 shown in FIG. 2 may include a charging control sub-circuit 210, a signal storage sub-circuit 220, a first driving sub-circuit 230, and a second driving sub-circuit 240. It can be coupled to the OLED element as shown in FIG. 2 and drive the OLED element to work.
  • the charging control sub-circuit 210 may be coupled to the scan signal terminal G1, the data signal terminal DATA, and the first node N1, and is configured to be able to transfer to the first node under the control of the scan signal from the scan signal terminal G1.
  • the node N1 transmits the data signal from the data signal terminal DATA.
  • the signal storage sub-circuit 220 may be coupled with the first node N1 and the OLED element (at the second node N2), and is configured to be able to store the signal from the first node N1 or transmit the stored signal to the first node N1.
  • the first driving sub-circuit 230 may be coupled to the first node N1, the first voltage signal terminal VDD1, and the OLED element (at the second node N2), and is configured to be able to control the level of the first node N1.
  • the OLED element transmits the first voltage signal from the first voltage signal terminal VDD1.
  • the second driving sub-circuit 240 may be coupled to the first node N1, the second voltage signal terminal VDD2, and the OLED element (at the second node N2), and is configured to be able to control the level of the first node N1.
  • the OLED element transmits the second voltage signal from the second voltage signal terminal VDD2.
  • FIG. 3 is a schematic diagram showing an example specific configuration of a pixel driving circuit 300 (for example, the pixel driving circuit 200 shown in FIG. 2) according to an embodiment of the present disclosure. Similar to the pixel driving circuit 200 shown in FIG. 2, the pixel driving circuit 300 shown in FIG. 3 may also include a charging control sub-circuit 310, a signal storage sub-circuit 320, a first driving sub-circuit 330, and a second driving sub-circuit 340. . It can be coupled with the OLED element as shown in FIG. 3 (at the second node N2), and drive the OLED element to work.
  • the charge control sub-circuit 310 may include a first transistor T1, the control terminal of which may be coupled to the scan signal terminal G1, the first terminal may be coupled to the data signal terminal DATA, and the second terminal may be Coupled with the first node N1.
  • the charge control sub-circuit 310 can transmit the data signal from the data signal terminal DATA to the first node N1 under the control of the scan signal from the scan signal terminal G1.
  • the signal storage sub-circuit 320 may include a first capacitor C1, the first terminal of which may be coupled to the first node N1, and the second terminal of which may be coupled to the OLED element. In other words, the signal storage sub-circuit 320 can store the signal from the first node N1 or transmit the stored signal to the first node N1.
  • the first driving sub-circuit 330 may include a second transistor T2, the control terminal of which may be coupled to the first node N1, the first terminal may be coupled to the first voltage signal terminal VDD1, and the second terminal may be coupled to the OLED element (in the Two nodes N2) are coupled.
  • the first driving sub-circuit 330 can transmit the first voltage signal from the first voltage signal terminal VDD1 to the OLED element under the control of the level of the first node N1.
  • the second driving sub-circuit 340 may include a third transistor T3, the control terminal of which is coupled to the first node N1, the first terminal is coupled to the second voltage signal terminal VDD2, and the second terminal may be connected to the OLED element (at the second node N2) coupling.
  • the second driving sub-circuit 340 can transmit the second voltage signal from the second voltage signal terminal VDD2 to the OLED element under the control of the level of the first node N1.
  • FIG. 4 is a timing chart showing an example operation of the pixel driving circuit 300 shown in FIG. 3.
  • the driving method of the pixel driving circuit 300 shown in FIG. 4 will be described in detail below in conjunction with FIG. 3.
  • the method of driving the pixel driving circuit 300 shown in FIG. 4 includes the following operations in one frame period.
  • the scan signal terminal G1 can input a high-level scan signal
  • the data signal terminal DATA can input a data signal (for example, in the embodiment shown in FIG. 4, with the highest gray level (for example, 255) )
  • the first voltage signal terminal VDD1 and the second voltage signal terminal VDD2 can respectively input low-level first and second voltage signals, so that the pixel driving circuit 300 can send the corresponding The OLED element outputs a low-level drive signal.
  • the scan signal terminal G1 inputs a high-level scan signal to the pixel drive circuit 300 of the current pixel (for example, scans the pixel row to which the current pixel belongs), so the first transistor T1 is turned on Therefore, the data signal from the data signal terminal DATA is transmitted to (or written into) the first node N1, and then the first capacitor C1 is charged, so that the voltage across the first capacitor C1 is the same as the data signal.
  • both the first voltage signal and the second voltage signal may be low-level (for example, zero-level) voltage signals, and therefore the first capacitor C1 may not be affected, and thus It does not affect the level of the first node N1, as shown in FIG. 4.
  • the first voltage signal and the second voltage signal may not be low-level voltage signals.
  • one of the two can be a high-level voltage signal, so that through the bootstrap action of the first capacitor C1, the level of the first node N1 is pulled to a higher level, which is similar to that shown in FIG. 4 Compared with the timing chart, the level of the first node N1 is pulled up to a higher level in advance, which can also enable the pixel driving circuit 300 to work.
  • the level of the second node N2 is also low, and the OLED element is In this stage, no light is emitted or light is emitted at a minimum gray scale.
  • the scan signal terminal G1 can input a low-level scan signal
  • the first voltage signal terminal VDD1 can input a high-level or low-level first voltage signal
  • the second voltage signal terminal VDD2 can Correspondingly, a low-level or high-level second voltage signal is input
  • the pixel driving circuit 300 can output a driving signal corresponding to the data signal to the OLED element to drive the OLED element to emit light in a corresponding gray scale.
  • the scan signal terminal G1 inputs a low-level scan signal to the pixel drive circuit 300 of the current pixel (for example, scans other pixel rows except the pixel row to which the current pixel belongs), so the first transistor T1 is turned off .
  • the first capacitor C1 may maintain the level of the first node N1.
  • the level of the data signal is higher than the threshold voltage of the second transistor T2 in the signal writing phase t1
  • the level of the first node N1 in the light-emitting phase t2 still remains higher than the threshold voltage of the second transistor T2
  • the second transistor T2 is turned on, so that the first voltage signal from the first voltage signal terminal VDD1 and the second voltage signal from the second voltage signal terminal VDD2 are transmitted to the second node N2.
  • one of the first voltage signal and the second voltage signal can always maintain a high-level signal, while the other is in an open circuit state or a low-level signal state, that is, the first voltage signal terminal
  • the corresponding one of VDD1 or the second voltage signal terminal VDD2 maintains a floating state.
  • the first voltage signal terminal VDD1 inputs a high-level first voltage signal and the second voltage signal terminal VDD2 floats
  • the first voltage signal is transmitted to the second node N2 through the second transistor T2 and then drives the OLED element to emit light .
  • the third transistor T3 since the third transistor T3 is also turned on under the control of the first node N1 at this time, the first voltage signal will also be transmitted to the third transistor T3.
  • the second voltage signal terminal VDD2 is floating at this time, All the current formed under the action of the first voltage signal will flow through the OLED element for driving it to emit light.
  • the direction of the source-drain voltage is opposite to the direction of the source-drain voltage when the first voltage signal terminal VDD1 is floating.
  • the possible threshold voltage drift of T2 and the third transistor T3 is compensated.
  • the second voltage signal is transmitted to the second node N2 through the third transistor T3 and then drives the OLED element to emit light.
  • the second transistor T2 since the second transistor T2 is also turned on under the control of the first node N1 at this time, the second voltage signal will also be transmitted to the second transistor T2.
  • the first voltage signal terminal VDD1 is floating at this time, All the current formed under the action of the second voltage signal will flow through the OLED element for driving it to emit light.
  • the direction of the source-drain voltage is opposite to the direction of the source-drain voltage when the second voltage signal terminal VDD2 is floating.
  • the possible threshold voltage drift of T2 and the third transistor T3 is compensated.
  • one of the first voltage signal and the second voltage signal outputs a signal for driving the OLED element (a high-level signal in this embodiment), the first voltage signal and the second voltage
  • the other one of the signals outputs an invalid signal (in this embodiment, a low-level signal) or floats, so that by switching the first voltage signal and the second voltage signal, the first driving sub-circuit 330 and the second driving sub-circuit
  • the switching between the sub-circuits 340 realizes the cooperative work of multiple driving sub-circuits, reduces the driving time of a single driving sub-circuit, avoids or reduces the threshold drift phenomenon of the TFT in the driving sub-circuit, thereby improving the display quality of the display.
  • the problem of threshold voltage drift that may occur when they are in a unidirectional voltage state for a long time is alleviated.
  • the second transistor T2 and the third transistor T3 are periodically in working or resting state during the light-emitting phase t2, and therefore, the threshold voltage drift that may occur when they are in a unidirectional current working state for a long time is reduced The problem.
  • the second node N2 since the second node N2 always maintains a high level during the light-emitting period t2, under the bootstrap action of the first capacitor C1, the level of the first node N1 is further increased as shown in FIG. 4, and the second transistor is maintained T2 and the third transistor T3 are in a conducting state, so that the voltage signals of the first voltage signal terminal VDD1 and the second voltage signal terminal VDD2 can continue to be output to the OLED element until the end of one frame period.
  • the work cycle of the next frame can be started, similar to the previous description.
  • the corresponding sub-pixel does not emit light in the next frame of the picture (for example, since the picture is pure red, neither the blue sub-pixel nor the green sub-pixel in the corresponding pixel emits light)
  • the data signal at the terminal DATA is low, the first node N1 always remains low, and the second transistor T2 and the third transistor T3 also remain off in the next frame, so that the corresponding OLED element does not emit light .
  • each input/output voltage signal may not be a square wave as shown in Figure 4, but a waveform that jitters slightly over time, or the rising/falling edge of the pulse is not as shown in the figure. 4 is the same vertical, but there is a certain slope change.
  • the duty ratios of the first voltage signal and the second voltage signal in the light-emitting period t2 are generally 50% each, but the present disclosure is not limited thereto. In other words, in other embodiments, there may be two voltage signals with different duty cycles. In some extreme examples, as long as there are two voltage signals to alternately drive the OLED element, the effect of reducing the threshold drift of a single driving transistor can be achieved.
  • the pixel driving circuit 200 or 300 may further include one or more third driving sub-circuits.
  • Each third driving sub-circuit can be coupled to the first node N1, the corresponding third voltage signal terminal and the OLED element (at the second node N2), and is configured to be able to control the level of the first node N1
  • the third voltage signal from the corresponding third voltage signal terminal is transmitted downward to the OLED element.
  • one or more transistors connected in parallel with the second transistor T2 and the third transistor T3 may be added between the first node N1 and the second node N2, so that these The control terminal of the transistor is coupled to the first node N1, the first terminal is coupled to the respective third voltage signal terminal, and the second terminal is coupled to the second node N2.
  • the working sequence shown in FIG. 4 can be modified so that the first voltage signal terminal VDD1, the second voltage signal terminal VDD2, and one or more third voltage signal terminals always keep one of them capable of driving during the light-emitting period t2.
  • the effective level of the OLED element (high level in this embodiment), while the rest remain floating or inactive levels (low level in this embodiment), so that the corresponding pixel drive circuit can further reduce the single
  • the working time of the driving transistor avoids or at least reduces the threshold voltage drift of a single driving transistor.
  • the switching period may be a few milliseconds, a few tenths of a millisecond or more. Short and so on, but the present disclosure is not limited to this.
  • the period of switching between the first voltage signal from the first voltage signal terminal VDD1 and the second voltage signal from the second voltage signal terminal VDD2 may range from 1 second to several hours.
  • the voltage signal terminal for driving the OLED element is switched every multiple frames.
  • the alternate opening and closing of the first voltage signal terminal VDD1 and the second voltage signal terminal VDD2 can be performed periodically by using one or more of peripheral circuits, chips, capacitors, and pulse switches. control.
  • the data signal corresponding to the maximum gray scale is input from the data signal terminal DATA in one frame and the data signal corresponding to the minimum gray scale is input in the next frame.
  • the data signal corresponding to the gray level that the current pixel/sub-pixel should be displayed can be input from the data signal terminal DATA.
  • a data signal corresponding to any one of gray scales 0, 1, 2, ..., 255 can be input, so that the pixel drive circuit 200/300
  • the associated OLED element (or any other display element) can emit light in a corresponding gray scale.
  • the present disclosure is not limited thereto.
  • the current formed by the first voltage signal from the first voltage signal terminal VDD1 can flow into the third transistor T3 through the second transistor T2, and then flow to the second voltage signal terminal VDD2.
  • the second voltage signal terminal VDD2 is grounded, it is equivalent to the second transistor T2 receiving a positive voltage and the third transistor T3 receiving a negative voltage.
  • the current formed by the second voltage signal from the second voltage signal terminal VDD2 can flow into the second transistor T2 through the third transistor T3, and then flow to the first voltage signal Terminal VDD1, the second transistor T2 receives a negative voltage and the third transistor T3 receives a positive voltage. In this way, the positive and negative voltage can repair or reduce the threshold voltage drift of the driving transistor.
  • the voltage of the corresponding drive voltage signal terminal is modified. Signal, allowing the monitor to continue to work normally.
  • the voltage signal terminal corresponding to the driving transistor in question can be turned off for a long time, and only the remaining driving transistors can be used to drive the OLED element. In other words, while reducing the threshold voltage drift problem, it provides redundancy and robustness for the display panel.
  • N-type transistor is used as an example, the present disclosure is not limited thereto.
  • P-type transistors can also be used.
  • one driving transistor may be an N-type transistor, and the other driving transistor may be a P-type transistor.
  • the pixel driving circuit 300 shown in FIG. 3 is only one way to realize the pixel driving circuit 200 shown in FIG. 2, and the present disclosure is not limited to this.
  • the switching sub-circuit controls the first driving sub-circuit 230 and the second driving sub-circuit 240 to drive the OLED elements in turn to reduce the time for each driving sub-circuit to individually drive the OLED elements, thereby avoiding or reducing the long-term unidirectional conduction of the thin film transistor Threshold voltage drift caused by the state.
  • the semiconductor active layer material of the above-mentioned thin film transistor can be any material that can be used as a semiconductor.
  • the semiconductor material can be a thin film containing at least one of the following: In (indium), Ga (gallium), Zn (zinc), 0 (oxygen), Sn (tin) and other elements .
  • the solution described in the present disclosure is also applicable.
  • the pixel driving circuit according to the embodiment of the present disclosure may be used in a driving circuit formed by any one of oxide thin film transistors, amorphous silicon thin film transistors, polysilicon thin film transistors, organic thin film transistors, and the like.
  • the pixel driving circuit of FIGS. 5 to 7 further adds a sensing sub-circuit for compensation, which can detect the actual driving current used to drive the OLED element and provide The external sensing compensation sub-circuit report, so that the sensing compensation sub-circuit can adjust the data voltage provided in the next frame, and then compensate the threshold voltage of the driving transistor in the pixel driving circuit, making the display effect more stable and further avoiding After-image, mura and other phenomena appear, improve product yield.
  • FIG. 5 is a schematic diagram showing an example configuration of a pixel driving circuit 500 according to another embodiment of the present disclosure. Similar to the pixel driving circuit 200 shown in FIG. 2, the pixel driving circuit 500 shown in FIG. 5 may also include a charging control sub-circuit 510, a signal storage sub-circuit 520, a first driving sub-circuit 530, and a second driving sub-circuit 540. It can be coupled to the OLED element as shown in FIG. 5 and drive the OLED element to work.
  • the charging control sub-circuit 510, the signal storage sub-circuit 520, the first driving sub-circuit 530, and the second driving sub-circuit 540 and the charging control sub-circuit 210, the signal storage sub-circuit 220, and the first driving sub-circuit 230 shown in FIG. It is substantially similar to the second driving sub-circuit 240, and therefore a detailed description thereof is omitted.
  • the pixel driving circuit 500 may further include a sensing sub-circuit 550.
  • the sensing sub-circuit 550 can be coupled to the sensing scan signal terminal G2, the OLED element (at the second node N2), and the sensing output signal terminal SENSE, and is configured to be capable of scanning from the sensing Under the control of the sensing scan signal of the signal terminal G2, a driving signal (original) for driving the OLED element is transmitted to the sensing output signal terminal SENSE as a sensing output signal.
  • the sensing sub-circuit 550 can sense the actual driving signal used to drive the OLED element, and feed it back to the external sensing and compensation sub-circuit to adjust the subsequent data signal to compensate
  • the threshold voltage of the driving transistor drifts to further avoid after-image, mura and other phenomena, and improve product yield.
  • FIG. 6 is a schematic diagram showing an example specific configuration of a pixel driving circuit 600 (for example, the pixel driving circuit 500 shown in FIG. 5) according to another embodiment of the present disclosure. Similar to the pixel driving circuit 500 shown in FIG. 5, the pixel driving circuit 600 shown in FIG. 6 may also include a charging control sub-circuit 610, a signal storage sub-circuit 620, a first driving sub-circuit 630, and a second driving sub-circuit 640. ⁇ sensing sub-circuit 650. It can be coupled to the OLED element as shown in FIG. 6 and drive the OLED element to work.
  • the specific configurations of the charge control sub-circuit 610, the signal storage sub-circuit 620, the first driving sub-circuit 630, and the second driving sub-circuit 640 are substantially the same as the specific configurations of the corresponding charging control sub-circuit 310, signal storage sub-circuit 320, first driving sub-circuit 330, and second driving sub-circuit 340 shown in FIG.
  • the sensing sub-circuit 650 are described in detail.
  • the sensing sub-circuit 650 may include a fourth transistor T4, the control terminal of which may be coupled to the sensing scan signal terminal G2, and the first terminal may be coupled to the OLED element (at the second node N2), And the second terminal can be coupled to the sensing output signal terminal SENSE.
  • the sensing sub-circuit 650 can transmit (originally) a driving signal for driving the OLED element as a sensing output signal to the sensing output signal terminal SENSE under the control of the sensing scan signal from the sensing scan signal terminal G2.
  • the circuit design shown in FIG. 6 it is possible to switch between the first driving sub-circuit 630 and the second driving sub-circuit 640 to realize the cooperative work of multiple driving sub-circuits and reduce the driving time of a single driving sub-circuit. , Avoid or reduce the threshold drift phenomenon of the TFT in the driving sub-circuit, thereby improving the display quality of the display.
  • the sensing sub-circuit 650 the sensed driving signal can be compensated to further avoid or reduce the threshold drift phenomenon of the TFT in the driving sub-circuit, thereby further improving the display quality of the display.
  • FIG. 7 is a timing chart showing an example operation of the pixel driving circuit 600 shown in FIG. 6.
  • the driving method of the pixel driving circuit 600 shown in FIG. 7 will be described in detail below in conjunction with FIG. 6. Similar to the method shown in FIG. 4, the method of driving the pixel driving circuit 600 shown in FIG. 7 also includes the following operations in one frame period:
  • the scan signal terminal G1 can input a scan signal of an effective level (high level in this embodiment)
  • the data signal terminal DATA can input a data signal
  • the two voltage signal terminals VDD2 can respectively input the first voltage signal and the second voltage signal of the invalid level (low level in this embodiment), so that the pixel driving circuit 600 can output the invalid level (in the In this embodiment, it is a low-level drive signal.
  • the scan signal terminal G1 can input a scan signal of an invalid level (low level in this embodiment), and one of the first voltage signal terminal VDD1 and the second voltage signal terminal VDD2 can be input to drive the OLED
  • the active level of the element high level in this embodiment
  • the other input inactive level low level in this embodiment
  • the driving signal corresponding to the data signal drives the OLED element to emit light in corresponding gray scales.
  • the method further includes a sensing phase (t3) in one frame period.
  • the scan signal terminal G1 inputs a scan signal of an invalid level (low level in this embodiment), and the sensing scan signal terminal G2 can input an effective level (high level in this embodiment).
  • Level) sensing scan signal one of the first voltage signal terminal VDD1 and the second voltage signal terminal VDD2 can input an effective level capable of driving the OLED element, and the other can input an invalid level or keep floating, and sense
  • the signal output terminal SENSE can output a driving signal corresponding to the data signal as a sensing output signal.
  • the sensing phase t3 since the scan signal terminal G1, the first voltage signal terminal VDD1 and the second voltage signal terminal VDD2 input the same signal as in the light-emitting phase t2, the first transistor T1, the second transistor T2, and the The working states of the third transistor T3, the first capacitor C1, etc. are similar to those in the light-emitting phase t2, and will not be described in detail here.
  • the fourth transistor T4 is turned on, so the driving current originally used to drive the OLED element in the light-emitting phase t2 can pass in the sensing phase t3
  • the fourth transistor T4 is output from the sensing output signal terminal SENSE, so that the external sensing compensation sub-circuit can adjust the subsequent data signal according to the sensing output signal.
  • the corresponding sub-pixel does not emit light in the next frame of the picture (for example, because the picture is pure purple, the green sub-pixel in the corresponding pixel does not emit light), so the data signal from the data signal terminal DATA is Low level, the first node N1 always maintains low level, the second transistor T2 and the third transistor T3 also maintain the off state in the next frame, so that the corresponding OLED element does not emit light, and the sensing sub-circuit
  • the sensing output signal sensed and output by the 650 is also a low level indicating no light emission.
  • each input/output voltage signal may not be a square wave as shown in Figure 7, but a waveform that jitters slightly over time, or the rising/falling edge of the pulse is not as shown in the figure. 7 is the same vertical, but there is a certain slope change.
  • the duty ratios of the first voltage signal and the second voltage signal in the light emitting phase t2 and the sensing phase t3 are generally 50% respectively, but the present disclosure is not limited thereto.
  • the effect of reducing the threshold drift of a single driving transistor can be achieved.
  • FIG. 8 is a flowchart illustrating an example method 800 of driving pixel driving circuits 200, 300, 500, and/or 600 according to an embodiment of the present disclosure.
  • the method 800 may include steps 810 and 820. According to the present disclosure, some steps of the method 800 can be executed individually or in combination, and can be executed in parallel or sequentially, and are not limited to the specific operation sequence shown in FIG. 8. In some embodiments, the method 800 may be executed by each pixel driving circuit described herein or another external device.
  • the method 800 may start at step 810.
  • the scan signal terminal may input a scan signal of an effective level (high level in this embodiment)
  • the data signal terminal may input a data signal
  • the first voltage signal terminal and the second voltage signal terminal can respectively input the first voltage signal and the second voltage signal of an invalid level (low level in this embodiment)
  • the pixel driving circuit can output to the corresponding OLED element Inactive level (low level in this embodiment) drive signal.
  • the scan signal terminal in the light-emitting phase, can input a scan signal of an invalid level (low level in this embodiment), and one of the first voltage signal terminal and the second voltage signal terminal can be input to drive the OLED
  • the effective level of the element, the other input an inactive level or remain floating, and the pixel driving circuit can output a driving signal corresponding to the data signal to the OLED element to drive the OLED element to emit light in a corresponding gray scale.
  • the method 800 may further include step 830, which is a sensing phase.
  • the scan signal terminal can input an invalid level (low level in this embodiment) scan signal
  • the sensing scan signal terminal can input an effective level (high level in this embodiment).
  • the sensing scan signal one of the first voltage signal terminal and the second voltage signal terminal can input an effective level capable of driving the OLED element, the other can input an inactive level or remain floating, and the sensing signal output terminal can The drive signal corresponding to the data signal is output as a sensing output signal.
  • a display panel is also provided, which may include any one or more of the pixel driving circuits described above.
  • a display device which may include the display panel as described above.
  • the threshold voltage drift of the oxide thin film transistor can be effectively suppressed, thereby reducing the possibility of problems such as residual image and mura in the display, and improving the product Yield rate, life span, etc.
  • functions described in this document as being implemented by pure hardware, pure software and/or firmware can also be implemented by means of special hardware, a combination of general hardware and software, etc.
  • functions described as being implemented by dedicated hardware e.g., field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc.
  • general-purpose hardware e.g., central processing unit (CPU), digital signal processing It can be realized by a combination of DSP and software, and vice versa.

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Abstract

一种像素驱动电路（200）及其驱动方法、显示面板和显示装置，像素驱动电路（200）包括：充电控制子电路（210），被配置为能够在来自扫描信号端的扫描信号的控制下向第一节点（N1）传输来自数据信号端的数据信号；信号存储子电路（220），被配置为能够存储来自第一节点（N1）的信号或向第一节点（N1）传输所存储的信号；第一驱动子电路（230），被配置为能够在第一节点（N1）的电平的控制下向有机发光二极管（OLED）元件传输来自第一电压信号端的第一电压信号；以及第二驱动子电路（240），被配置为能够在第一节点（N1）的电平的控制下向有机发光二极管（OLED）元件传输来自第二电压信号端的第二电压信号。

Description

像素驱动电路及其驱动方法、显示面板和显示装置
交叉引用
本公开要求于2019年4月23日提交的发明名称为“像素驱动电路及其驱动方法、显示面板和显示装置”的中国专利申请201910331176.8的优先权益，在此引出以将其一并并入本文。
技术领域
本公开涉及显示技术领域，且更具体地涉及像素驱动电路及其驱动方法、显示面板和显示装置。
背景技术
近年来，随着显示技术的快速发展，薄膜晶体管(TFT)技术由原来的非晶硅(a-Si)薄膜晶体管发展到现在的低温多晶硅(LTPS)薄膜晶体管、金属诱导横向晶化(MILC)薄膜晶体管、氧化物(Oxide)薄膜晶体管等，而发光技术也由原来的液晶显示器(LCD)、等离子显示面板(PDP)发展为现在的有机发光二极管(OLED)显示器。
OLED是新一代的显示器件，其与液晶显示器相比，具有很多优点，例如：自发光、响应速度快、宽视角等等。其可以用于柔性显示、透明显示、3D显示等。有源矩阵有机发光显示器(AMOLED)为每一个像素配备了用于控制该像素的开关，例如薄膜晶体管。因此，通过驱动电路，可以独立控制每一个像素，同时不会对其它像素造成串扰等的影响。薄膜晶体管通常至少包含栅极、源极和漏极以及栅绝缘层和有源层。
目前，薄膜晶体管的有源层主要为硅，其可以是非晶硅或者多晶硅。采用非晶硅作为有源层的薄膜晶体管，因其特性的限制(如迁移率、开态电流等)，难以用于需要较大电流和快速响应的场合，如有机发光显示器和大尺寸、高分辨率、高刷新频率的显示器等。相对地，采用多晶硅作为有源层的薄膜晶体管，其特性优于非晶硅，可以用于有机发光显示器。但是，因其均匀性不佳，制备中大尺寸的面板仍有困难。为此， 可以用增加补偿电路的方式来处理多晶硅特性不均匀的问题，但这同时也增加了像素中的薄膜晶体管和电容的数量，增加了掩膜数量和制作难度，造成产量减低和良率下降。另外，如果采用诸如准分子激光退火(ELA)等的LTPS技术来对非晶硅进行晶化，还将需要增加昂贵的设备和维护费用。
因此，氧化物半导体日益受到重视。以氧化物半导体为有源层的薄膜晶体管的特性优于非晶硅，如迁移率、开态电流、开关特性等。虽然特性不如多晶硅，但足以用于需要快速响应和较大电流的应用，如高频、高分辨率、大尺寸的显示器以及有机发光显示器等。此外，氧化物的均匀性较好，与多晶硅相比，由于没有均匀性问题，不需要增加补偿电路，在掩膜数量和制作难度上均有优势。在制作大尺寸的显示器方面也没有难度。而且采用溅射等方法就可以制备，不需增加额外的设备，具有成本优势。氧化物薄膜晶体管所采用的氧化物半导体材料，具有高氧含量时能表现很好的半导体特性，具有较低氧含量时具有较低的电阻率，因此可作为透明电极使用。
然而，氧化物薄膜晶体管的缺点是稳定性较差，在驱动过程中其阈值电压(Vth)会发生漂移，使画面显示出现如残像、不均匀光斑(Mura)等缺陷，导致产品良率大幅度降低。
发明内容
根据一个方面，本公开的实施例提供了一种像素驱动电路。该像素驱动电路包括：充电控制子电路，与扫描信号端、数据信号端和第一节点耦接，并被配置为能够在来自所述扫描信号端的扫描信号的控制下向所述第一节点传输来自所述数据信号端的数据信号；信号存储子电路，与所述第一节点和有机发光二极管“OLED”元件耦接，并被配置为能够存储来自所述第一节点的信号或向所述第一节点传输所存储的信号；第一驱动子电路，与所述第一节点、第一电压信号端和所述OLED元件耦接，并被配置为能够在所述第一节点的电平的控制下向所述OLED元件传输来自所述第一电压信号端的第一电压信号；以及第二驱动子电路， 与所述第一节点、第二电压信号端和所述OLED元件耦接，并被配置为能够在所述第一节点的电平的控制下向所述OLED元件传输来自所述第二电压信号端的第二电压信号。
在一些实施例中，所述充电控制子电路包括：第一晶体管，其控制端与所述扫描信号端耦接，第一端与所述数据信号端耦接，以及第二端与所述第一节点耦接。在一些实施例中，所述信号存储子电路包括：第一电容器，其第一端与所述第一节点耦接，以及第二端与所述OLED元件耦接。在一些实施例中，所述第一驱动子电路包括：第二晶体管，其控制端与所述第一节点耦接，第一端与所述第一电压信号端耦接，以及第二端与所述OLED元件耦接。在一些实施例中，所述第二驱动子电路包括：第三晶体管，其控制端与所述第一节点耦接，第一端与所述第二电压信号端耦接，以及第二端与所述OLED元件耦接。在一些实施例中，所述像素驱动电路还包括：感测子电路，与感测扫描信号端、所述OLED元件、感测输出信号端耦接，并被配置为能够在来自所述感测扫描信号端的感测扫描信号的控制下向所述感测输出信号端传输用于驱动所述OLED元件的驱动信号作为感测输出信号。在一些实施例中，所述感测子电路包括：第四晶体管，其控制端与所述感测扫描信号端耦接，第一端与所述OLED元件耦接，以及第二端与所述感测输出信号端耦接。在一些实施例中，所述像素驱动电路还包括：一个或多个第三驱动子电路，每个所述第三驱动子电路与所述第一节点、相应的第三电压信号端和所述OLED元件耦接，并被配置为能够在所述第一节点的电平的控制下向所述OLED元件传输来自相应的第三电压信号端的第三电压信号。
根据另一方面，提供了一种显示面板。该显示面板包括上述像素驱动电路。
根据又一方面，提供了一种显示装置，包括上述显示面板。
根据再一方面，提供了一种用于驱动上述像素驱动电路的方法。在一帧周期中，该方法包括以下操作：在信号写入阶段，扫描信号端输入有效电平的扫描信号，数据信号端输入数据信号，第一电压信号端和第二电压信号端分别输入无效电平的第一电压信号和第二电压信号，以及 所述像素驱动电路向相应的有机发光二极管“OLED”元件输出低电平的驱动信号；以及在发光阶段，扫描信号端输入无效电平的扫描信号，第一电压信号端和第二电压信号端之一输入能够驱动OLED元件的有效电平，另一个输入无效电平或保持浮置，以及所述像素驱动电路向所述OLED元件输出与所述数据信号相对应的驱动信号，以驱动所述OLED以相应灰阶发光。
在一些实施例中，在一帧周期中所述方法还包括以下操作：在感测阶段，扫描信号端输入无效电平的扫描信号，感测扫描信号端输入有效电平的感测扫描信号，第一电压信号端和第二电压信号端之一输入能够驱动OLED元件的有效电平，另一个输入无效电平或保持浮置，以及感测信号输出端输出与所述数据信号相对应的驱动信号，作为感测输出信号。
根据再一方面，提供了一种用于驱动上述像素驱动电路的方法。在一帧周期中，该方法包括以下操作：在信号写入阶段，扫描信号端输入有效电平的扫描信号，数据信号端输入数据信号，第一电压信号端和第二电压信号端以及第三电压信号端分别输入无效电平的第一电压信号和第二电压信号以及第三电压信号，以及所述像素驱动电路向相应的有机发光二极管“OLED”元件输出无效电平的驱动信号；以及在发光阶段，扫描信号端输入无效电平的扫描信号，第一电压信号端和第二电压信号端以及一个或多个第三电压信号端之一输入能够驱动OLED元件的有效电平，其他电压信号端输入无效电平或保持浮置，以及所述像素驱动电路向所述OLED元件输出与所述数据信号相对应的驱动信号，以驱动所述OLED元件以相应灰阶发光。
附图说明
通过下面结合附图说明本公开的优选实施例，将使本公开的上述及其它目的、特征和优点更加清楚，其中：
图1是示出了根据相关技术的像素驱动电路的示例具体构造的示意图。
图2是示出了根据本公开实施例的像素驱动电路的示例构造的示意图。
图3是示出了图2所示的像素驱动电路的示例具体构造的示意图。
图4是示出了图3所示的像素驱动电路的示例工作时序图。
图5是示出了根据本公开另一实施例的像素驱动电路的示例构造的示意图。
图6是示出了图5所示的像素驱动电路的示例具体构造的示意图。
图7是示出了图6所示的像素驱动电路的示例工作时序图。
图8是示出了根据本公开实施例的用于驱动像素驱动电路的示例方法的流程图。
具体实施方式
下面参照附图对本公开的部分实施例进行详细说明，在描述过程中省略了对于本公开来说是不必要的细节和功能，以防止对本公开的理解造成混淆。在本说明书中，下述用于描述本公开原理的各种实施例只是说明，不应该以任何方式解释为限制公开的范围。参照附图的下述描述用于帮助全面理解由权利要求及其等同物限定的本公开的示例性实施例。下述描述包括多种具体细节来帮助理解，但这些细节应认为仅仅是示例性的。因此，本领域普通技术人员应认识到，在不脱离本公开的范围和精神的情况下，可以对本文中描述的实施例进行多种改变和修改。此外，为了清楚和简洁起见，省略了公知功能和结构的描述。此外，贯穿附图，相同的附图标记用于相同或相似的功能、器件和/或操作。此外，在附图中，各部分并不一定按比例来绘制。换言之，附图中的各部分的相对大小、长度等并不一定与实际比例相对应。
在本公开中，术语“包括”和“含有”及其派生词意为包括而非限制；术语“或”是包含性的，意为和/或。此外，在本公开的以下描 述中，所使用的方位术语，例如“上”、“下”、“左”、“右”等均用于指示相对位置关系，以辅助本领域技术人员理解本公开实施例，且因此本领域技术人员应当理解：在一个方向上的“上”/“下”，在相反方向上可变为“下”/“上”，且在另一方向上，可能变为其它位置关系，例如“左”/“右”等。
以下，以本公开实施例应用于OLED显示装置的像素驱动电路为例来详细说明。然而本领域技术人员应当理解本公开的应用领域不限于此。事实上，根据本公开实施例的像素驱动电路等可以应用于其它需要使用像素驱动电路的领域中，例如LCD显示装置等。
此外，尽管在以下描述中以晶体管为N型晶体管为例进行了描述，然而本公开不限于此。事实上，如本领域技术人员所能够理解的：当以下提及的各个晶体管中的一个或多个为P型晶体管时同样可以实现本申请的技术方案，只需对电平设置和/或耦接关系进行相应的调整即可。下文中，将能够导通相应晶体管的电平称为有效电平，将关断相应晶体管的电平称为无效电平，在以晶体管为N型晶体管为例进行的描述中，有效电平为高电平，无效电平为低电平。相应的，在以晶体管为P型晶体管为例进行的描述中，有效电平为高低电平，无效电平为高电平。
图1是示出了根据相关技术的像素驱动电路100的示例具体构造的示意图。如图1所示，像素驱动电路100包括第一晶体管T1、第二晶体管T2、第四晶体管T4和第一电容器C1。
第一晶体管T1的控制端与扫描信号端G1耦接，其第一端与数据信号端DATA耦接，以及第二端与第一节点N1耦接。第一晶体管T1可以在来自扫描信号端G1的扫描信号的控制下将来自数据信号端DATA的数据信号写入第一节点N1。
第一电容器C1的一端与第一节点N1耦接，以及另一端与第二节点N2耦接。第一电容器C1可以用于保存被写入第一节点N1的数据信号，并在第一晶体管T1关断时维持第一节点N1的信号电平。
第二晶体管T2的控制端与第一节点N1耦接，其第一端与第一电压信号端VDD耦接，以及第二端与第二节点N2耦接。第二晶体管T2可以在第一节点N1的电平的控制下向第二节点N2(进而向OLED元件) 提供来自电压信号端VDD的电压/电流信号，以驱动OLED元件正常工作。
第四晶体管T4的控制端与感测扫描信号端G2耦接，其第一端与第二节点N2耦接，以及第二端与感测输出信号端SENSE耦接。第四晶体管T4可以在来自感测扫描信号端G2的感测扫描信号的控制下，向感测输出信号端SENSE输出其感测到的通过第二节点N2的驱动电流，以使得与感测输出信号端SENSE耦接的外部补偿电路能够根据该驱动电流对后续帧的驱动电流加以补偿，从而避免或减少由于第二晶体管T2在长期导通状态下发生的阈值漂移所引起的工作不良。这样。通过采用这样的电路结构，可以实现对OLED元件的驱动。
然而，如前所述，由于在此过程中随着第二晶体管T2工作时间的延长，其阈值电压会发生漂移。特别是如果其一直处于导通状态且电流极性一直不变，则更容易发生阈值电压的单向漂移，进而使OLED元件表现出变暗或者变亮。在大尺寸上应用时，由于在不同区域的像素驱动电路中的温度、电流不同，使屏幕的不同区域处显示出残像、Mura、亮暗不均等缺陷。
为了解决或至少部分既减轻上述问题，提出了根据本公开实施例的像素驱动电路及其驱动方法、以及包括像素驱动电路在内的显示面板和显示装置。总体上，可以通过设置多个驱动晶体管来减少单个驱动晶体管的驱动时间，从而避免或减少单个驱动晶体管出现阈值电压漂移的现象，由此提升像素驱动电路乃至显示面板、显示装置的寿命。更具体地，在一些实施例中，当第一驱动晶体管工作时第二驱动晶体管可处于休息状态，而当第二驱动晶体管工作时第一驱动管可处于休息状态。
以下，将结合图2～图4来描述根据本公开实施例的示例像素驱动电路的构造和工作原理。
图2是示出了根据本公开实施例的像素驱动电路200的示例构造的示意图。根据图2所示的像素驱动电路200可以包括充电控制子电路210、信号存储子电路220、第一驱动子电路230和第二驱动子电路240。其可以如图2所示与OLED元件耦接，并驱动OLED元件工作。
如图2所示，充电控制子电路210可以与扫描信号端G1、数据信号端DATA和第一节点N1耦接，并被配置为能够在来自扫描信号端G1 的扫描信号的控制下向第一节点N1传输来自数据信号端DATA的数据信号。信号存储子电路220可以与第一节点N1和OLED元件(在第二节点N2处)耦接，并被配置为能够存储来自第一节点N1的信号或向第一节点N1传输所存储的信号。第一驱动子电路230可以与第一节点N1、第一电压信号端VDD1和OLED元件(在第二节点N2处)耦接，并被配置为能够在第一节点N1的电平的控制下向OLED元件传输来自第一电压信号端VDD1的第一电压信号。第二驱动子电路240可以与第一节点N1、第二电压信号端VDD2和OLED元件(在第二节点N2处)耦接，并被配置为能够在第一节点N1的电平的控制下向OLED元件传输来自第二电压信号端VDD2的第二电压信号。
通过采用如图2所示的电路设计，可以在第一驱动子电路230和第二驱动子电路240之间切换，实现多个驱动子电路协同工作，减少单个驱动子电路的驱动时间，避免或减少驱动子电路中的TFT的阈值漂移现象，从而提升显示器的显示质量。接下来，将结合图3来详细描述图2所示的像素驱动电路的具体构造。
图3是示出了根据本公开实施例的像素驱动电路300(例如，图2所示的像素驱动电路200)的示例具体构造的示意图。与图2所示的像素驱动电路200类似，图3所示的像素驱动电路300也可以相应包括充电控制子电路310、信号存储子电路320、第一驱动子电路330和第二驱动子电路340。其可以如图3所示与OLED元件耦接(在第二节点N2处)，并驱动OLED元件工作。
在图3所示实施例中，充电控制子电路310可以包括第一晶体管T1，其控制端可以与扫描信号端G1耦接，第一端可以与数据信号端DATA耦接，以及第二端可以与第一节点N1耦接。换言之，充电控制子电路310能够在来自扫描信号端G1的扫描信号的控制下向第一节点N1传输来自数据信号端DATA的数据信号。
信号存储子电路320可以包括第一电容器C1，其第一端可以与第一节点N1耦接，以及第二端可以与OLED元件耦接。换言之，信号存储子电路320能够存储来自第一节点N1的信号或向第一节点N1传输所存储的信号。
第一驱动子电路330可以包括第二晶体管T2，其控制端可以与第一节点N1耦接，第一端可以与第一电压信号端VDD1耦接，以及第二端可以与OLED元件(在第二节点N2处)耦接。换言之，第一驱动子电路330能够在第一节点N1的电平的控制下向OLED元件传输来自第一电压信号端VDD1的第一电压信号。
第二驱动子电路340可以包括第三晶体管T3，其控制端与第一节点N1耦接，第一端与第二电压信号端VDD2耦接，以及第二端可以与OLED元件(在第二节点N2处)耦接。换言之，第二驱动子电路340能够在第一节点N1的电平的控制下向OLED元件传输来自第二电压信号端VDD2的第二电压信号。
同样地，通过采用如图3所示的电路设计，可以在第一驱动子电路330和第二驱动子电路340之间切换，实现多个驱动子电路协同工作，减少单个驱动子电路的驱动时间，避免或减少驱动子电路中的TFT的阈值漂移现象，从而提升显示器的显示质量。接下来，将结合图4来详细描述图3所示的像素驱动电路300的工作流程。
图4是示出了根据图3所示的像素驱动电路300的示例工作时序图。以下将结合图3来详细说明图4所示的像素驱动电路300的驱动方法。图4所示的驱动像素驱动电路300的方法在一帧周期中包括以下操作。
在信号写入阶段(t1)，扫描信号端G1可输入高电平的扫描信号，数据信号端DATA可输入数据信号(例如，在图4所示实施例中，与最高灰阶(例如，255)相对应的高电平数据信号)，第一电压信号端VDD1和第二电压信号端VDD2可分别输入低电平的第一电压信号和第二电压信号，从而像素驱动电路300可向相应的OLED元件输出低电平的驱动信号。
具体地，在信号写入阶段t1中，扫描信号端G1针对当前像素的像素驱动电路300输入高电平的扫描信号(例如，对当前像素所属的像素行进行扫描)，所以第一晶体管T1导通，从而使得来自数据信号端DATA的数据信号传输至(或写入)第一节点N1，并进而对第一电容器C1充电，使得第一电容器C1两端的电压与数据信号相同。此外，当数 据信号的电平高于第二晶体管T2的阈值电压(Vth)时，第二晶体管T2导通，从而使得来自第一电压信号端VDD1的第一电压信号传输至第二节点N2，并使得来自第二电压信号端VDD2的第二电压信号也传输至第二节点N2。如图4所示，在信号写入阶段t1中，第一电压信号和第二电压信号都可以是低电平(例如，零电平)电压信号，且因此第一电容器C1可不受影响，进而不对第一节点N1的电平产生影响，如图4所示。
然而，需要注意的是：在另一些实施例中，在信号写入阶段t1中，第一电压信号和第二电压信号也可以不是低电平电压信号。例如，这二者之一可以是高电平电压信号，从而通过第一电容器C1的自举作用，将第一节点N1的电平拉升至更高的电平，从而与图4所示的时序图相比，提前将第一节点N1的电平拉升至更高的电平，这同样可以使得像素驱动电路300能够工作。
回到图4，在该实施例中，由于第一电压信号和第二电压信号在阶段t1都是低电平电压信号，因此第二节点N2的电平同样为低电平，且OLED元件在该阶段中不发光或以最低限度的灰阶发光。
此外，在发光阶段(t2)，扫描信号端G1可输入低电平的扫描信号，第一电压信号端VDD1可输入高电平或低电平的第一电压信号，第二电压信号端VDD2可相应输入低电平或高电平的第二电压信号，以及像素驱动电路300可向OLED元件输出与数据信号相对应的驱动信号，以驱动OLED元件以相应灰阶发光。
具体地，扫描信号端G1针对当前像素的像素驱动电路300输入低电平的扫描信号(例如，对除了当前像素所属的像素行之外的其它像素行进行扫描)，所以第一晶体管T1关断。在第一晶体管T1关断的情况下，第一电容器C1可保持第一节点N1的电平。换言之，当在信号写入阶段t1中数据信号的电平高于第二晶体管T2的阈值电压时，在发光阶段t2中第一节点N1的电平依然保持高于第二晶体管T2的阈值电压，使得第二晶体管T2导通，进而使得来自第一电压信号端VDD1的第一电压信号和来自第二电压信号端VDD2的第二电压信号传输至第二节点N2。如图4所示，在发光阶段t2中，第一电压信号和第二电压信号之一可 始终保持高电平信号，同时另一个呈开路状态或低电平信号状态，即第一电压信号端VDD1或第二电压信号端VDD2中的相应一个保持浮置(floating)状态。
例如，当第一电压信号端VDD1输入高电平的第一电压信号且第二电压信号端VDD2浮置时，第一电压信号经过第二晶体管T2传输至第二节点N2并进而驱动OLED元件发光。同时，由于此时第三晶体管T3在第一节点N1的控制下也导通，从而第一电压信号也会传输到第三晶体管T3，然而由于第二电压信号端VDD2此时浮置，因此在第一电压信号的作用下所形成的全部电流都会流经OLED元件，用于驱动其发光。虽然电流全部流经OLED元件，但对于第三晶体管T3而言，其源漏电压方向与在第一电压信号端VDD1浮置情况下的源漏电压方向相反，从而在一定程度上对第二晶体管T2和第三晶体管T3可能出现的阈值电压漂移进行了补偿。
此外，当第一电压信号端VDD1浮置且第二电压信号端VDD2输入高电平的第二电压信号时，第二电压信号经过第三晶体管T3传输至第二节点N2并进而驱动OLED元件发光。同时，由于此时第二晶体管T2在第一节点N1的控制下也导通，从而第二电压信号也会传输到第二晶体管T2，然而由于第一电压信号端VDD1此时浮置，因此在第二电压信号的作用下所形成的全部电流都会流经OLED元件，用于驱动其发光。虽然电流全部流经OLED元件，但对于第二晶体管T2而言，其源漏电压方向与在第二电压信号端VDD2浮置情况下的源漏电压方向相反，从而在一定程度上对第二晶体管T2和第三晶体管T3可能出现的阈值电压漂移进行了补偿。
也就是说，在发光阶段t2中，第一电压信号和第二电压信号之一输出用于驱动OLED元件的信号(在该实施例中为高电平信号)，第一电压信号和第二电压信号中的另一个输出无效信号(在该实施例中为低电平信号)或浮置，这样通过第一电压信号和第二电压信号的切换，可以在第一驱动子电路330和第二驱动子电路340之间切换，实现多个驱动子电路协同工作，减少单个驱动子电路的驱动时间，避免或减少驱动子电路中的TFT的阈值漂移现象，从而提升显示器的显示质量。
换言之，在发光阶段t2中，由于第二晶体管T2和第三晶体管T3的源漏电压方向周期性改变，因此减轻了其长期处于单向加压状态下所可能出现的阈值电压漂移的问题。或者从电流的角度来看，第二晶体管T2和第三晶体管T3在发光阶段t2中周期性处于工作或休息状态，且因此减轻了其长期处于单向电流工作状态下所可能出现的阈值电压漂移的问题。
此外，由于第二节点N2在发光阶段t2中始终保持高电平，因此在第一电容器C1的自举作用下，第一节点N1的电平如图4所示进一步增高，并保持第二晶体管T2和第三晶体管T3处于导通状态，使得，第一电压信号端VDD1和第二电压信号端VDD2的电压信号能够持续向OLED元件输出，直至一帧周期结束。
接下来，可以开始下一帧的工作周期，与前面描述的类似。然而，如果如图4所示，在下一帧画面中相应子像素不发光(例如，由于画面为纯红色，则相应像素内的蓝色子像素和绿色子像素都不发光)，从而来自数据信号端DATA的数据信号为低电平，则第一节点N1始终保持低电平，第二晶体管T2和第三晶体管T3也都在该下一帧中保持关断状态，从而使得相应OLED元件不发光。
需要注意的是：图4所示的工作时序图仅仅是用于说明的一个实施例，其与实际的工作时序图可能并不相同。例如，在一些实施例中，各输入/输出电压信号可能不像图4所示的那样为方波，而是会出现随时间发生微小抖动的波形，或者脉冲的上升沿/下降沿并非如图4一样竖直，而是存在一定斜率变化。此外，在图4所示实施例中，第一电压信号和第二电压信号在发光阶段t2中的占空比大体上各50％，然而本公开不限于此。换言之，在另一些实施例中，可以存在具有不同占空比的两个电压信号。在一些极端的示例中，只要存在两个电压信号交替驱动OLED元件，都可以实现减轻单一驱动晶体管的阈值漂移问题的效果。
此外，尽管图2～图4所示的实施例中仅示出了两个驱动子电路(例如，第一驱动子电路230/330和第二驱动子电路240/340)，然而本公开不限于此。例如，在一些实施例中，像素驱动电路200或300还可以包括一个或多个第三驱动子电路。每个第三驱动子电路可以与第一节点 N1、相应的第三电压信号端和OLED元件(在第二节点N2处)耦接，并被配置为能够在第一节点N1的电平的控制下向OLED元件传输来自相应的第三电压信号端的第三电压信号。
具体地，在例如图3所示的像素驱动电路300中，可以在第一节点N1和第二节点N2之间增加与第二晶体管T2和第三晶体管T3并联的一个或多个晶体管，使得这些晶体管的控制端耦接到第一节点N1，第一端耦接到各自的第三电压信号端，且第二端耦接到第二节点N2。此外，可以对图4所示的工作时序进行修改，使得第一电压信号端VDD1、第二电压信号端VDD2和一个或多个第三电压信号端在发光阶段t2中始终保持其中一个为能够驱动OLED元件的有效电平(在该实施例中为高电平)，而其余保持浮置或为无效电平(在该实施例中为低电平)，从而使得相应像素驱动电路能够进一步减少单个驱动晶体管的工作时间，避免或至少减轻单个驱动晶体管的阈值电压漂移问题的出现。
此外，尽管在图4所示实施例中，在一帧期间在第一电压信号端VDD1和第二电压信号端VDD2之间进行多次切换，其切换周期可以是几毫秒、零点几毫秒或更短等，但本公开不限于此。在另一些实施例中，在来自第一电压信号端VDD1的第一电压信号和来自第二电压信号端VDD2的第二电压信号之间进行切换的周期可以从1秒钟到数小时不等，例如每隔多个帧来切换用于驱动OLED元件的电压信号端。此外，在一些实施例中，第一电压信号端VDD1和第二电压信号端VDD2的交替开和闭可通过采用外围电路、芯片、电容器、脉冲开关等中的一项或多项来进行周期性控制。
此外，尽管在图4所示实施例中，仅示出了来自数据信号端DATA在一帧中输入与最大灰阶相对应的数据信号以及在下一帧中输入与最小灰阶相对应的数据信号，但本公开不限于此。换言之，在另一些实施例中，完全可以从数据信号端DATA输入与当前像素/子像素所应当显示的灰阶相对应的数据信号。例如，在采用256等级灰阶(0～255)的情况下，可以输入与灰阶0、1、2、…、255中任一个相对应的数据信号，以使得与该像素驱动电路200/300相关联的OLED元件(或任何其它显示元件)能够以相应灰阶发光。
此外，尽管在图2～图4所示实施例中，将第一电压信号端VDD1和第二电压信号端VDD2描述为在发光阶段t2中轮流处于浮置状态，但本公开不限于此。换言之，例如，在一个周期中，来自第一电压信号端VDD1的第一电压信号所形成的电流可以经由第二晶体管T2流入第三晶体管T3，进而流向第二电压信号端VDD2。此时，如果第二电压信号端VDD2接地，则相当于第二晶体管T2受到正电压而第三晶体管T3受到负电压。如果下一周期反过来，即第一电压信号端VDD1接地，来自第二电压信号端VDD2的第二电压信号所形成的电流可以经由第三晶体管T3流入第二晶体管T2，进而流向第一电压信号端VDD1，则第二晶体管T2受到负电压且第三晶体管T3受到正电压。这样时正时负的电压可以修复或减轻驱动晶体管的阈值电压漂移问题。
此外，在一些实施例中，由于存在多个驱动晶体管(例如，第二晶体管T2和第三晶体管T3)，则在这些驱动晶体管中的一些驱动晶体管出现问题时，通过修改相应驱动电压信号端的电压信号，可以让显示器继续正常工作。例如，可以将与出现问题的驱动晶体管相对应的电压信号端长期关闭，而只用其余的驱动晶体管来驱动OLED元件。换言之，在减轻了阈值电压漂移问题的同时，为显示面板提供了冗余性和鲁棒性。
此外，尽管在图3所示实施例中，采用了N型晶体管作为示例之用，但本公开不限于此。在另一些实施例中，也可以采用P型晶体管。在又一些实施例中，一个驱动晶体管可以是N型晶体管，而另一个驱动晶体管可以是P型晶体管。
此外，需要注意的是：图3所示的像素驱动电路300仅是实现图2所示的像素驱动电路200的一种方式，而本公开不限于此。例如，除了通过控制第一电压信号端VDD1和第二电压信号端VDD2各自的电压信号来切换第一驱动子电路230和第二驱动子电路240轮流驱动OLED元件之外，也可以通过设置单独的切换子电路来控制第一驱动子电路230和第二驱动子电路240轮流驱动OLED元件来使得每个驱动子电路单独驱动OLED元件的时间减少，从而避免或减轻其薄膜晶体管长时间处于单向导通状态下所产生的阈值电压漂移问题。
此外，在一些实施例中，上述薄膜晶体管的半导体活化层材料可 以是任何可以作为半导体的材料。例如，对于氧化物薄膜晶体管，其半导体材料可以是包含以下中至少一项在内的薄膜：In(铟)、Ga(镓)、Zn(锌)、0(氧)、Sn(锡)等元素。此外，对于其它材料如a-Si、P-Si等，本公开所述方案同样适用。换言之，根据本公开实施例的像素驱动电路可以用于氧化物薄膜晶体管、非晶硅薄膜晶体管、多晶硅薄膜晶体管、有机薄膜晶体管等的任何一种形成的驱动电路。
接下来，将结合图5～图7来描述根据本公开另一实施例的示例像素驱动电路的构造和工作原理。与图2～4所示的像素驱动电路相比，图5～图7的像素驱动电路进一步增加了用于补偿的感测子电路，其可以通过检测用于驱动OLED元件的实际驱动电流并向外部的感测补偿子电路报告，以使得感测补偿子电路能够调整在下一帧中提供的数据电压，进而对像素驱动电路中的驱动晶体管的阈值电压加以补偿，使得显示效果更加稳定，进一步避免出现残像、Mura等现象，提升产品良率。
图5是示出了根据本公开另一实施例的像素驱动电路500的示例构造的示意图。与图2所示的像素驱动电路200类似，图5所示的像素驱动电路500也可以包括充电控制子电路510、信号存储子电路520、第一驱动子电路530和第二驱动子电路540。其可以如图5所示与OLED元件耦接，并驱动OLED元件工作。鉴于充电控制子电路510、信号存储子电路520、第一驱动子电路530和第二驱动子电路540与图2所示的充电控制子电路210、信号存储子电路220、第一驱动子电路230和第二驱动子电路240大体相似，且因此省略对其的详细描述。
此外，在图5所示实施例中，像素驱动电路500还可以包括感测子电路550。如图5所示，感测子电路550可以与感测扫描信号端G2、OLED元件(在第二节点N2处)、感测输出信号端SENSE耦接，并被配置为能够在来自感测扫描信号端G2的感测扫描信号的控制下向感测输出信号端SENSE传输(原本)用于驱动OLED元件的驱动信号作为感测输出信号。
通过如下面结合图7所描述的工作流程，感测子电路550可以感测用于驱动OLED元件的实际驱动信号，并向外部的感测补偿子电路反馈，以调整后续的数据信号，进而补偿驱动晶体管的阈值电压漂移，进 一步避免出现残像、Mura等现象，提升产品良率。接下来，将结合图6来详细描述图5所示的像素驱动电路的具体构造。
图6是示出了根据本公开另一实施例的像素驱动电路600(例如，图5所示的像素驱动电路500)的示例具体构造的示意图。与图5所示的像素驱动电路500类似，图6所示的像素驱动电路600也可以相应包括充电控制子电路610、信号存储子电路620、第一驱动子电路630、第二驱动子电路640和感测子电路650。其可以如图6所示与OLED元件耦接，并驱动OLED元件工作。
如前所述，充电控制子电路610、信号存储子电路620、第一驱动子电路630和第二驱动子电路640的具体构造(例如，第一晶体管T1、第二晶体管T2、第三晶体管T3和第一电容器C1等)与图3所示的相应充电控制子电路310、信号存储子电路320、第一驱动子电路330和第二驱动子电路340的具体构造大体相同，且因此这里省略对其的详细描述，而仅详细描述与感测子电路650有关的元件。
如图6所示，感测子电路650可以包括第四晶体管T4，其控制端可以与感测扫描信号端G2耦接，第一端可以与OLED元件(在第二节点N2处)耦接，以及第二端可以与感测输出信号端SENSE耦接。换言之，感测子电路650能够在来自感测扫描信号端G2的感测扫描信号的控制下向感测输出信号端SENSE传输(原本)用于驱动OLED元件的驱动信号作为感测输出信号。
同样地，通过采用如图6所示的电路设计，可以在第一驱动子电路630和第二驱动子电路640之间切换，实现多个驱动子电路协同工作，减少单个驱动子电路的驱动时间，避免或减少驱动子电路中的TFT的阈值漂移现象，从而提升显示器的显示质量。此外，通过设置感测子电路650，可以通过对感测到的驱动信号进行补偿来进一步避免或减少驱动子电路中的TFT的阈值漂移现象，从而进一步提升显示器的显示质量。接下来，将结合图7来详细描述图6所示的像素驱动电路的工作流程。
图7是示出了根据图6所示的像素驱动电路600的示例工作时序图。以下将结合图6来详细说明图7所示的像素驱动电路600的驱动方法。与图4所示的方法类似，图7所示的驱动像素驱动电路600的方法 在一帧周期中也包括以下操作：
在信号写入阶段(t1)，扫描信号端G1可输入有效电平(在该实施例中为高电平)的扫描信号，数据信号端DATA可输入数据信号，第一电压信号端VDD1和第二电压信号端VDD2可分别输入无效电平(在该实施例中为低电平)的第一电压信号和第二电压信号，从而像素驱动电路600可向相应的OLED元件输出无效电平(在该实施例中为低电平)的驱动信号。
在发光阶段(t2)，扫描信号端G1可输入无效电平(在该实施例中为低电平)的扫描信号，第一电压信号端VDD1和第二电压信号端VDD2之一输入能够驱动OLED元件的有效电平(在该实施例中为高电平)，另一个输入无效电平(在该实施例中为低电平)或保持浮置，从而像素驱动电路600可向OLED元件输出与数据信号相对应的驱动信号，以驱动OLED元件以相应灰阶发光。
鉴于图7所示的这两个阶段与图4所示的相应阶段类似，因此这里不再对其进行详细描述。以下，将仅详细描述与感测子电路650有关的阶段。
如图7所示，在一帧周期中方法还包括感测阶段(t3)。
在感测阶段(t3)，扫描信号端G1输入无效电平(在该实施例中为低电平)的扫描信号，感测扫描信号端G2可输入有效电平(在该实施例中为高电平)的感测扫描信号，第一电压信号端VDD1和第二电压信号端VDD2之一可输入能够驱动OLED元件的有效电平，另一个可输入无效电平或保持浮置，以及感测信号输出端SENSE可输出与数据信号相对应的驱动信号，作为感测输出信号。
具体地，在感测阶段t3中，由于扫描信号端G1、第一电压信号端VDD1和第二电压信号端VDD2与发光阶段t2中输入相同的信号，因此第一晶体管T1、第二晶体管T2、第三晶体管T3、第一电容器C1等的工作状态与发光阶段t2中类似，在此不再详细描述。此外，由于感测扫描信号端G2输入高电平的感测扫描信号，因此第四晶体管T4导通，所以在发光阶段t2中原本用于驱动OLED元件的驱动电流在感测阶段t3中可通过第四晶体管T4从感测输出信号端SENSE向外输出，以使得 外部的感测补偿子电路能够根据该感测输出信号来调整后续的数据信号。
接下来，开始下一帧的工作周期，与前面描述的类似。然而，如果如图7所示，在下一帧画面中相应子像素不发光(例如，由于画面为纯紫色，则相应像素内的绿色子像素不发光)，从而来自数据信号端DATA的数据信号为低电平，则第一节点N1始终保持低电平，第二晶体管T2和第三晶体管T3也都在该下一帧中保持关断状态，从而使得相应OLED元件不发光，而感测子电路650所感测并输出的感测输出信号也相应地为指示不发光的低电平。
需要注意的是：图7所示的工作时序图仅仅是用于说明的一个实施例，其与实际的工作时序图可能并不相同。例如，在一些实施例中，各输入/输出电压信号可能不像图7所示的那样为方波，而是会出现随时间发生微小抖动的波形，或者脉冲的上升沿/下降沿并非如图7一样竖直，而是存在一定斜率变化。此外，在图7所示实施例中，第一电压信号和第二电压信号在发光阶段t2和感测阶段t3中的占空比大体上各50％，然而本公开不限于此。换言之，在另一些实施例中，可以存在具有不同占空比的两个电压信号。在一些极端的示例中，只要存在两个电压信号交替驱动OLED元件，都可以实现减轻单一驱动晶体管的阈值漂移问题的效果。
以下，将结合图8来详细描述根据本公开实施例的用于驱动像素驱动电路的方法。
图8是示出了根据本公开实施例的驱动像素驱动电路200、300、500和/或600的示例方法800的流程图。如图8所示，方法800可以包括步骤810和820。根据本公开，方法800的一些步骤可以单独执行或组合执行，以及可以并行执行或顺序执行，并不局限于图8所示的具体操作顺序。在一些实施例中，方法800可以由本文所述各像素驱动电路或另一外部设备执行。
方法800可以开始于步骤810，在步骤810中，在信号写入阶段，扫描信号端可输入有效电平(在该实施例中为高电平)的扫描信号，数据信号端可输入数据信号，第一电压信号端和第二电压信号端可分别输 入无效电平(在该实施例中为低电平)的第一电压信号和第二电压信号，以及像素驱动电路可向相应的OLED元件输出无效电平(在该实施例中为低电平)的驱动信号。
在步骤820中，在发光阶段，扫描信号端可输入无效电平(在该实施例中为低电平)的扫描信号，第一电压信号端和第二电压信号端之一可输入能够驱动OLED元件的有效电平，另一个输入无效电平或保持浮置，以及像素驱动电路可向OLED元件输出与数据信号相对应的驱动信号，以驱动OLED元件以相应灰阶发光。
在一些实施例中，对于例如具有感测子电路的像素驱动电路(例如，像素驱动电路500或600)，方法800还可以包括步骤830，即感测阶段。在该感测阶段中，扫描信号端可输入无效电平(在该实施例中为低电平)的扫描信号，感测扫描信号端可输入有效电平(在该实施例中为高电平)的感测扫描信号，第一电压信号端和第二电压信号端之一可输入能够驱动OLED元件的有效电平，另一个可输入无效电平或保持浮置，以及感测信号输出端可输出与数据信号相对应的驱动信号，作为感测输出信号。
此外，根据本公开的一些实施例，还提供了显示面板，其可以包括如上所述的任一种或多种像素驱动电路。
此外，根据本公开的一些实施例，还提供了显示装置，其可以包括如上所述的显示面板。
通过使用根据本公开实施例的像素驱动电路及其驱动方法、显示面板和显示装置，可以有效抑制氧化物薄膜晶体管的阈值电压漂移，进而减少显示器中出现残像、Mura等问题的可能性，提升产品良率、寿命等。
至此已经结合优选实施例对本公开进行了描述。应该理解，本领域技术人员在不脱离本公开的精神和范围的情况下，可以进行各种其它的改变、替换和添加。因此，本公开的范围不局限于上述特定实施例，而应由所附权利要求所限定。
此外，在本文中被描述为通过纯硬件、纯软件和/或固件来实现的功能，也可以通过专用硬件、通用硬件与软件的结合等方式来实现。例 如，被描述为通过专用硬件(例如，现场可编程门阵列(FPGA)、专用集成电路(ASIC)等)来实现的功能，可以由通用硬件(例如，中央处理单元(CPU)、数字信号处理器(DSP))与软件的结合的方式来实现，反之亦然。

Claims (13)

  1. 一种像素驱动电路，包括：
    充电控制子电路，与扫描信号端、数据信号端和第一节点耦接，并被配置为能够在来自所述扫描信号端的扫描信号的控制下向所述第一节点传输来自所述数据信号端的数据信号；
    信号存储子电路，与所述第一节点和有机发光二极管“OLED”元件耦接，并被配置为能够存储来自所述第一节点的信号或向所述第一节点传输所存储的信号；
    第一驱动子电路，与所述第一节点、第一电压信号端和所述OLED元件耦接，并被配置为能够在所述第一节点的电平的控制下向所述OLED元件传输来自所述第一电压信号端的第一电压信号；以及
    第二驱动子电路，与所述第一节点、第二电压信号端和所述OLED元件耦接，并被配置为能够在所述第一节点的电平的控制下向所述OLED元件传输来自所述第二电压信号端的第二电压信号。
  2. 根据权利要求1所述的像素驱动电路，其中，所述充电控制子电路包括：
    第一晶体管，其控制端与所述扫描信号端耦接，第一端与所述数据信号端耦接，以及第二端与所述第一节点耦接。
  3. 根据权利要求1所述的像素驱动电路，其中，所述信号存储子电路包括：
    第一电容器，其第一端与所述第一节点耦接，以及第二端与所述OLED元件耦接。
  4. 根据权利要求1所述的像素驱动电路，其中，所述第一驱动子电路包括：
    第二晶体管，其控制端与所述第一节点耦接，第一端与所述第一电压信号端耦接，以及第二端与所述OLED元件耦接。
  5. 根据权利要求1所述的像素驱动电路，其中，所述第二驱动子电路包括：
    第三晶体管，其控制端与所述第一节点耦接，第一端与所述第二电压信号端耦接，以及第二端与所述OLED元件耦接。
  6. 根据权利要求1所述的像素驱动电路，还包括：
    感测子电路，与感测扫描信号端、所述OLED元件、感测输出信号端耦接，并被配置为能够在来自所述感测扫描信号端的感测扫描信号的控制下向所述感测输出信号端传输用于驱动所述OLED元件的驱动信号作为感测输出信号。
  7. 根据权利要求6所述的像素驱动电路，其中，所述感测子电路包括：
    第四晶体管，其控制端与所述感测扫描信号端耦接，第一端与所述OLED元件耦接，以及第二端与所述感测输出信号端耦接。
  8. 根据权利要求1所述的像素驱动电路，还包括：
    一个或多个第三驱动子电路，每个所述第三驱动子电路与所述第一节点、相应的第三电压信号端和所述OLED元件耦接，并被配置为能够在所述第一节点的电平的控制下向所述OLED元件传输来自相应的第三电压信号端的第三电压信号。
  9. 一种显示面板，包括根据权利要求1～8中任一项所述的像素驱动电路。
  10. 一种显示装置，包括根据权利要求9所述的显示面板。
  11. 一种用于驱动根据权利要求1～7中任一项所述的像素驱动电路的方法，在一帧周期中包括以下操作：
    在信号写入阶段，扫描信号端输入有效电平的扫描信号，数据信号端输入数据信号，第一电压信号端和第二电压信号端分别输入无效电平的第一电压信号和第二电压信号，以及所述像素驱动电路 向相应的有机发光二极管“OLED”元件输出无效电平的驱动信号；以及
    在发光阶段，扫描信号端输入无效电平的扫描信号，第一电压信号端和第二电压信号端之一输入能够驱动OLED元件的有效电平，另一个输入无效电平或保持浮置，以及所述像素驱动电路向所述OLED元件输出与所述数据信号相对应的驱动信号，以驱动所述OLED元件以相应灰阶发光。
  12. 根据权利要求11所述的方法，其中，在一帧周期中所述方法还包括以下操作：
    在感测阶段，扫描信号端输入无效电平的扫描信号，感测扫描信号端输入有效电平的感测扫描信号，第一电压信号端和第二电压信号端之一输入能够驱动OLED元件的有效电平，另一个输入无效电平或保持浮置，以及感测信号输出端输出与所述数据信号相对应的驱动信号，作为感测输出信号。
  13. 一种用于驱动根据权利要求8所述的像素驱动电路的方法，在一帧周期中包括以下操作：
    在信号写入阶段，扫描信号端输入有效电平的扫描信号，数据信号端输入数据信号，第一电压信号端和第二电压信号端以及第三电压信号端分别输入无效电平的第一电压信号和第二电压信号以及第三电压信号，以及所述像素驱动电路向相应的有机发光二极管“OLED”元件输出无效电平的驱动信号；以及
    在发光阶段，扫描信号端输入无效电平的扫描信号，第一电压信号端和第二电压信号端以及一个或多个第三电压信号端之一输入能够驱动OLED元件的有效电平，其他电压信号端输入无效电平或保持浮置，以及所述像素驱动电路向所述OLED元件输出与所述数据信号相对应的驱动信号，以驱动所述OLED元件以相应灰阶发光。
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