This application claims priority to Chinese Patent Application No. 202210337886.3 filed Mar. 31, 2022, the disclosure of which is incorporated herein by reference in its entirety.
Embodiments of the present disclosure relate to the field of display technologies and, in particular, to a pixel circuit, a driving method thereof, an array substrate, a display panel, and a display device.
With the development of display technologies, an organic light emitting diode (OLED) display is more and more widely used in the display field due to advantages of active light emission, a wide viewing angle, a high contrast ratio, low power consumption and fast response speed and gradually replace the traditional liquid crystal display (LCD).
To improve the display stability of the OLED, a pixel circuit that drives the OLED to emit light includes multiple transistors. Compared with low temperature polysilicon (LTPS) transistors, metal oxide (such as indium gallium zinc oxide (IGZO)) transistors have advantages of high transmittance, low electron mobility, a large on-off ratio and low power consumption. In the design of the existing pixel circuit, the IGZO transistors replace part of the LTPS transistors, so as to reduce the leakage current of the circuit. However, since two different types of transistors, that are LTPS P-type transistors and IGZO N-type transistors, exist in the pixel circuit, three sets of different scan circuits are required for driving in the pixel circuit so that a narrower frame cannot be obtained.
Embodiments of the present disclosure provide a pixel circuit, a driving method thereof, an array substrate, a display panel, and a display device. The pixel circuit only needs two sets of scan circuits for driving so that the peripheral driver circuit is simplified and a narrower frame of the display panel is achieved.
In a first aspect, an embodiment of the present disclosure provides a pixel circuit. The pixel circuit includes a drive module, a first initialization module, and a data write module.
A control terminal of the drive module is electrically connected to a first node, a first terminal of the drive module is electrically connected to a first power supply voltage terminal, and a second terminal of the drive module is electrically connected to a first electrode of a light-emitting element.
The first initialization module includes a first N-type transistor and a second N-type transistor, where a control terminal of the first N-type transistor is electrically connected to a scan signal terminal, a first terminal of the first N-type transistor is electrically connected to a first reference signal terminal, a second terminal of the first N-type transistor is electrically connected to a first terminal of the second N-type transistor, a control terminal of the second N-type transistor is electrically connected to an enable signal terminal, and a second terminal of the second N-type transistor is electrically connected to the first node.
A control terminal of the data write module is electrically connected to the scan signal terminal, a first terminal of the data write module is electrically connected to a data signal terminal, and a second terminal of the data write module is electrically connected to the first terminal of the drive module.
In a second aspect, an embodiment of the present disclosure further provides a driving method of a pixel circuit. The method is used for driving the preceding pixel circuit and includes steps described below.
In an initialization stage, a first initialization module is controlled to be turned on, a data write module and a drive module are controlled to be turned off, and the first initialization module initializes a potential of a first node.
In a data write stage, the data write module and the drive module are controlled to be turned on, the first initialization module is controlled to be turned off, and the data write module writes a data signal into the first node.
In a light emission stage, the drive module is controlled to be turned on, the data write module and the first initialization module are controlled to be turned off, the drive module provides a drive current to a light-emitting element, and the light-emitting element emits light in response to the drive current.
In a third aspect, an embodiment of the present disclosure further provides an array substrate including a display region, where the display region includes a plurality of pixel circuits arranged in an array.
In a fourth aspect, an embodiment of the present disclosure further provides a display panel including the preceding array substrate.
In a fifth aspect, an embodiment of the present disclosure further provides a display device including the preceding display panel.
The pixel circuit provided in the embodiments of the present disclosure includes a drive module, a first initialization module, and a data write module. A control terminal of the drive module is electrically connected to a first node, a first terminal of the drive module is electrically connected to a first power supply voltage terminal, and a second terminal of the drive module is electrically connected to a first electrode of a light-emitting element. The first initialization module includes a first N-type transistor and a second N-type transistor, where a control terminal of the first N-type transistor is electrically connected to a scan signal terminal, a first terminal of the first N-type transistor is electrically connected to a first reference signal terminal, a second terminal of the first N-type transistor is electrically connected to a first terminal of the second N-type transistor, a control terminal of the second N-type transistor is electrically connected to an enable signal terminal, and a second terminal of the second N-type transistor is electrically connected to the first node. A control terminal of the data write module is electrically connected to the scan signal terminal, a first terminal of the data write module is electrically connected to a data signal terminal, and a second terminal of the data write module is electrically connected to the first terminal of the drive module. Compared with the related art, the pixel circuit provided in the embodiments of the present disclosure only needs one scan signal terminal and one enable signal terminal, and only two sets of scan circuits need to be disposed for driving, which is conducive to simplifying the peripheral driver circuit and achieving a narrower frame of the display panel.
The present disclosure is further described hereinafter in detail in conjunction with drawings and embodiments. It is to be understood that embodiments described hereinafter are merely intended to explain the present disclosure and not to limit the present disclosure. Additionally, it is to be noted that for ease of description, only part, not all, of structures related to the present disclosure are illustrated in the drawings.
Terms used in embodiments of the present disclosure are merely used for describing the specific embodiments and not intended to limit the present disclosure. It is to be noted that spatially related terms, including “on”, “below”, “left” and “right” described in the embodiments of the present disclosure, are described from the perspective of the drawings and are not to be construed as a limitation to the embodiments of the present disclosure. In addition, in the context, it is to be understood that when a component is formed “on” or “below” another component, the component may not only be directly formed “on” or “below” another component and may also be indirectly formed “on” or “below” another component via an intermediate component. Terms “first”, “second” and the like are merely used for description and distinguishing between different components rather than indicating any order, quantity, or importance. For those of ordinary skill in the art, the preceding terms can be construed according to specific situations in the present disclosure.
To solve the preceding problem,
The drive module 10 is configured to drive the light-emitting element LED to emit light according to a data signal, and the drive module 10 may include a drive transistor formed by an N-type transistor or a P-type transistor. During specific implementation, the electrical connection between the first terminal of the drive module 10 and the first power supply voltage terminal PVDD may be direct electrical connection, indirect electrical connection by interposing other elements, or coupling connection. The data write module 30 is configured to write a data signal into the first node N1 under the control of the corresponding scan signal terminal S, and the data signal is used for controlling a magnitude of a drive current outputted by the drive module 10 so as to control the brightness of the light-emitting element. The data write module 30 may include a P-type transistor. The first initialization module 20 is configured to initialize a voltage of the first node N1, and a control signal outputted by the scan signal terminal S and a control signal outputted by the enable signal terminal Emit control the on and off of the first N-type transistor 21 and the second N-type transistor 22, respectively. The control terminal of the first N-type transistor 21 and the control terminal of the data write module 30 are connected to the same scan signal terminal S, thereby achieving the effect of reducing a set of scan circuits compared with the related art.
The pixel circuit provided in the embodiments of the present disclosure only needs one scan signal terminal and one enable signal terminal, and only two sets of scan circuits need to be disposed for driving, which is conducive to simplifying the peripheral driver circuit and achieving a narrower frame of the display panel.
The threshold compensation module 40 is configured to achieve the threshold compensation of a gate of the drive transistor in the drive module 10. During specific implementation, when the data write module 30 writes the data signal into the first node N1, the control signal of the enable signal terminal Emit controls the third N-type transistor 41 to be turned on, and a data voltage VData provided by the data signal terminal Data is written into the first node N1 through the drive module 10 and the third N-type transistor 41. A voltage of a second node N2 is VData, and a voltage of the first node N1 is VData-Vth, where Vth denotes a threshold voltage of the drive transistor in the drive module. A voltage related to Vth is prestored in the first node N1, and a quantity related to Vth in a current formula of the light-emitting element may be eliminated so that a current flowing through the light-emitting element is independent of Vth, thereby achieving threshold compensation.
Optionally, in this embodiment, the first N-type transistor 21, the second N-type transistor 22, and the third N-type transistor 41 are all transistors including oxide semiconductors, for example, IGZO transistors. In other embodiments, the first N-type transistor 21, the second N-type transistor 22, and the third N-type transistor 41 may also be other types of oxide semiconductor transistors, which may be selected according to actual conditions during specific implementation.
The storage module 50 is configured to maintain a potential of the first node N1 in the case where the light-emitting element LED is in a light emission stage. The second initialization module 60 is configured to reset the first electrode (for example, an anode) of the light-emitting element LED before the light-emitting element LED emits light, so as to avoid the light emission brightness being affected by the light emission last time. The first light emission control module 70 and/or the second light emission control module 80 are configured to be turned on during light emission so that the drive current flows through the light-emitting element LED, thereby emitting light. In this embodiment, the first electrode of the light-emitting element LED is an anode, the second electrode of the light-emitting element LED is a cathode, the first power supply voltage terminal PVDD provides an anode voltage, and the second power supply voltage terminal PVEE provides a cathode voltage.
It is to be understood that, since the first initialization module 20 and the second initialization module 60 may work in different time periods, two initialization signals may also be provided by a same signal line at different times. By way of example, in this embodiment, a first reference signal terminal Ref1 and a second reference signal terminal Ref2 are the same signal terminal, thereby reducing the number of wires and simplifying the pixel circuit structure.
Optionally, in this embodiment, the drive transistor M3, the fourth transistor M2, the fifth transistor M1, the sixth transistor M6, and the seventh transistor M7 are all P-type transistors. Further, the P-type transistor includes an LTPS semiconductor. The transistor formed by an LTPS process has advantages of high mobility and fast charging.
A specific structure of the pixel circuit provided in the embodiment of the present disclosure is introduced in the preceding embodiment. Compared with the existing pixel circuit, in the pixel circuit provided in the embodiment of the present disclosure, the number of scan circuits is reduced and the driving method is also different from the driving method in the related art. An operating principle of the pixel circuit is introduced in conjunction with the driving method of the pixel circuit.
In step S110, in an initialization stage, a first initialization module is controlled to be turned on, a data write module and a drive module are controlled to be turned off, and the first initialization module initializes a potential of a first node.
The initialization stage is the first stage of pixel circuit control and used for initializing the potential of the first node. A reference voltage provided by the first reference signal terminal Vref1 is written into the first node through the first initialization module. For example, in the case where the drive transistor in the drive module is a P-type transistor, the reference voltage is a low-level signal, and a voltage of the low-level signal may be specifically selected according to actual conditions.
In step S120, in a data write stage, the data write module and the drive module are controlled to be turned on, the first initialization module is controlled to be turned off, and the data write module writes a data signal into the first node.
The data write stage is the second stage of pixel circuit control and used for writing the data signal into the first node. Voltage values of data signals are different so that the degrees of conduction of the drive transistor in the drive module are different in the subsequent light emission stage, thereby controlling the magnitude of the drive current and controlling the light-emitting element to achieve display with different brightnesses.
In step S130, in a light emission stage, the drive module is controlled to be turned on, the data write module and the first initialization module are controlled to be turned off, the drive module provides a drive current to a light-emitting element, and the light-emitting element emits light in response to the drive current.
The light emission stage is the third stage of pixel circuit control. According to the input of different data voltages in the previous stage, the display with different brightnesses of the light-emitting element may be achieved. For the entire display panel, all pixel circuits are scanned row by row, thereby achieving picture display.
Optionally, the first initialization module includes a first N-type transistor and a second N-type transistor, where the control terminal of the first N-type transistor is electrically connected to the scan signal terminal S, and the control terminal of the second N-type transistor is connected to the enable signal terminal Emit. The pixel circuit further includes a threshold compensation module, where the threshold compensation module includes a third N-type transistor. The drive module includes a drive transistor M3, the data write module includes a fourth transistor M2, the first light emission control module includes a fifth transistor M1, the second light emission control module includes a sixth transistor M6, the second initialization module includes a seventh transistor M7, and the storage module includes a first capacitor Cst.
Referring to
It is to be understood that an N-type transistor is turned on in the case where a gate voltage is at a high level and a P-type transistor is turned on in the case where the gate voltage is at a low level. In the initialization stage T1, the scan signal terminal S outputs a high level, and the high level controls the first N-type transistor M5 to be turned on; the enable signal terminal Emit outputs a high level, and the high level controls the second N-type transistor M8 to be turned on. A reference voltage (a low level) provided by the first reference signal terminal Vref1 is inputted into the first node N1 through the first N-type transistor M5 and the second N-type transistor M8, thereby achieving the initialization of the first node N1. In this stage, the fifth transistor M1 and the sixth transistor M6 are turned off under the control of the high level provided by the enable signal terminal Emit, and the fourth transistor M2 and the seventh transistor M7 are turned off under the control of the high level provided by the scan signal terminal S.
Referring to
In the data write stage T2, the scan signal terminal S outputs a low level, the enable signal terminal Emit outputs a high level, the fourth transistor M2 is turned on under the control of the low level provided by the scan signal terminal S, and the third N-type transistor M4 is turned on under the control of the high level provided by the enable signal terminal Emit. Since in the initialization stage T1, a low level is written into the first node N1, the drive transistor M3 is also in an on state at this time, a data voltage provided by the data signal terminal Data is written into the first node N1 after passing through the fourth transistor M2, the drive transistor M3, and the third N-type transistor M4, and the threshold compensation of a gate of the drive transistor M3 is achieved at the same time. In this stage, the fifth transistor M1 and the sixth transistor M6 are turned off under the control of the high level provided by the enable signal terminal Emit. Although the second N-type transistor M8 is in the on state, the first N-type transistor M5 is turned off under the control of the low level provided by the scan signal terminal S. Therefore, the first initialization module is in an off state. In the data write stage T2, the seventh transistor M7 is turned on under the control of the low level provided by the scan signal terminal S, and a reference voltage provided by the second reference signal terminal Vref2 resets the first electrode of the light-emitting element LED.
Referring to
In the light emission stage T3, the scan signal terminal S1 outputs a high level, the enable signal terminal Emit outputs a low level, the fifth transistor M1 and the sixth transistor M6 are turned on under the control of the low level provided by the enable signal terminal Emit, the third N-type transistor M4 is turned off under the control of the low level provided by the enable signal terminal Emit, and the current provided by the first power supply voltage terminal PVDD flows through the fifth transistor M1, the drive transistor M3, and the sixth transistor M6 in sequence and into the light-emitting element LED, thereby achieving the display of the light-emitting element. In this stage, although the first N-type transistor M5 is turned on, the second N-type transistor M8 is turned off. Therefore, the first initialization module is turned off, and the seventh transistor M7 is turned off under the control of the high level provided by the scan signal terminal S.
To sum up, in the technical solutions of the embodiments of the present disclosure, only one scan signal terminal and one enable signal terminal are required for driving the corresponding pixel circuit so that a narrower frame of the display panel is achieved.
An embodiment of the present disclosure further provides an array substrate including a display region, where the display region includes multiple pixel circuits provided in any of the preceding embodiments arranged in an array. Since the array substrate provided in the embodiments of the present disclosure includes any one of the pixel circuits provided in the preceding embodiments, the array substrate has the technical effect of a narrow frame.
The first scan signal line S1 and the second scan signal line S2 may be connected to a same scan signal terminal (not shown in
With continued reference to
It is to be understood that a region where the scan signal line or the enable signal line overlaps the corresponding semiconductor active layer forms the gate of the transistor, and other elements are doped on two sides of the gate so as to form the source and drain of the transistor. For the connection between transistors formed by the same type of active layers, heavy doping is performed on the active layers, so as to achieve the conductive function; and for the connection between transistors formed by different types of active layers, connection may be achieved by using metal wires across the layers, which may be designed according to the actual circuit structure and layout during specific implementation.
The first semiconductor active layer 100 includes an LTPS semiconductor active layer, and the second semiconductor active layer 200 includes an oxide semiconductor active layer, such as an IGZO active layer.
With continued reference to
The signal lines and the active layers are in different layers, and a through hole may be provided at a corresponding position when connection between the signal lines and the active layers is required. For example, a circular (elliptical) region in
Optionally, the first semiconductor active layer and the second semiconductor active layer are electrically connected through a metal wire, where the metal wire is in a same layer as the data signal line or the first power supply voltage signal line.
Since the first semiconductor layer and the second semiconductor layer have different materials and are generally arranged in different layers, the first semiconductor layer and the second semiconductor layer cannot be directly electrically connected, so a connecting wire needs to be provided.
In this embodiment, the types of the first N-type transistor M5 and the seventh transistor M7 are different. To avoid direct connection between active layers of the first N-type transistor M5 and the seventh transistor M7, a first reference signal line ref1 and a second reference signal line ref2 are provided and connected to the first reference signal terminal Vref1 and the second reference signal terminal Vref2, respectively.
The first pixel circuit A1 and the second pixel circuit A2 are arranged symmetrically along the power supply voltage signal line VDD, which is conducive to reducing the number of power supply voltage signal lines VDD and simplifying the circuit structure. Moreover, a width of the power supply voltage signal line VDD is larger, which is conducive to reducing the resistance and the voltage drop.
The first shift register 511 and the second shift register 512 are both shift registers including multiple transistors and capacitors and are configured to provide control signals required by the gates of the transistors in the pixel circuit so as to control the on and off of corresponding transistors. The specific circuit structure may be selected according to actual conditions, which is not limited in the embodiments of the present disclosure. The position of the first shift register 511 on a side of the second shift register 512 closer to the display region 400 is merely illustrative, and the order of the first shift register 511 and the second shift register 512 is not limited in the embodiments of the present disclosure. In this embodiment, it is schematically shown that the shift register circuit 510 is located on left and right frames of the array substrate. In other embodiments, only one frame may be provided, or the first shift register 511 and the second shift register 512 may be are located on different frames.
The pixel circuit provided in the embodiments of the present disclosure includes two scan signal lines (the first scan signal line S1 and the second scan signal line S2 as shown in FIG. 11) and two enable signal lines (the first enable signal line Emit1 and the second enable signal line Emit2 as shown in
Optionally, the array substrate includes n rows of pixel circuits, and pixel circuits in each row is connected by a first scan signal line and a second scan signal line; the first shift registers include n stages of first sub-shift registers located in a first frame region and n stages of second sub-shift registers located in a second frame region; an output terminal of a first sub-shift register of an i-th stage is connected to both the first scan signal line and the second scan signal line in a pixel circuit in an i-th row, and an output terminal of a second sub-shift register of an i-th stage is connected to both the first scan signal line and the second scan signal line in a pixel circuit in the i-th row, where 0<i≤n, n≥2, and i and n are both integers.
Optionally, the array substrate includes n rows of pixel circuits, and pixel circuits in each row are connected by a first scan signal line and a second scan signal line; the first shift registers include n stages of first sub-shift registers located in a first frame region and n stages of second sub-shift registers located in a second frame region; an output terminal of a first sub-shift register of an i-th stage is connected to both the second scan signal line in a pixel circuit in an i-th row and the first scan signal line in a pixel circuit in an (i+j)-th row, and an output terminal of a second sub-shift register of an i-th stage is connected to both the second scan signal line in a pixel circuit in the i-th row and the first scan signal line in a pixel circuit in the (i+j)-th row, where 0<i≤n, and 0<j≤n−i; and i, j, and n are all integers.
Optionally, pixel circuits in each row are connected to by a first enable signal line and a second enable signal line; the second shift registers include n stages of third sub-shift registers located in the first frame region and n stages of fourth sub-shift registers located in the second frame region; an output terminal of a third sub-shift register of an i-th stage is connected to both the first enable signal line and the second enable signal line in a pixel circuit in the i-th row, and an output terminal of a fourth sub-shift register of an i-th stage is connected to both the first enable signal line and the second enable signal line in a pixel circuit in the i-th row, where 0<i≤n, n≥2, and i and n are both integers.
Optionally, pixel circuits in each row are connected by a first enable signal line and a second enable signal line; the second shift register includes n stages of third sub-shift registers located in the first frame region and n stages of fourth sub-shift registers located in the second frame region; an output terminal of a third sub-shift register of an i-th stage is connected to both the first enable signal line in a pixel circuit in the i-th row and the second enable signal line in a pixel circuit in the (i+j)-th row, and an output terminal of a fourth sub-shift register of an i-th stage is connected to both the first enable signal line in a pixel circuit in the i-th row and the second enable signal line in a pixel circuit in the (i+j)-th row, where 0<i≤n, and 0<j≤n−i; and i, j, and n are all integers.
By way of example,
Referring to
Referring to
Referring to
It is to be noted that, when the array substrate provided in the embodiments of the present disclosure drives the pixel circuits, a single-side driving method or a double-side driving method may be adopted. For example, when the scan signal lines are driven, the first sub-shift register and the second sub-shift register provide signals to the corresponding scan signal lines from two sides at the same time, which is the double-side driving; and while the first sub-shift register provides signals to one of the scan signal lines from the left side, the second sub-shift register provides signals to another scan signal line from the right side, which is the single-side driving method. The signal driving method is not limited in the embodiments of the present disclosure.
An embodiment of the present disclosure further provides a display panel including any one of the array substrates provided in the preceding embodiments. The display panel has the technical effect of a narrow frame.
It is to be noted that the preceding are only preferred embodiments of the present disclosure and technical principles used therein. It is to be understood by those skilled in the art that the present disclosure is not limited to the embodiments described herein. For those skilled in the art, various apparent modifications, adaptations, combinations, and substitutions can be made without departing from the scope of the present disclosure. Therefore, while the present disclosure has been described in detail via the preceding embodiments, the present disclosure is not limited to the preceding embodiments and may include more equivalent embodiments without departing from the inventive concept of the present disclosure. The scope of the present disclosure is determined by the scope of the appended claims.
Number | Date | Country | Kind |
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202210337886.3 | Mar 2022 | CN | national |