Patent Application
20250131878
The present disclosure relates to the field of display technologies, in particular to a pixel circuit, a driving method therefor, and a display device.
With the development of a display technology, people have higher and higher requirements for the display effect of display devices. At present, a brightness adjustment method of an active display device usually uses direct current (DC) dimming. However, when achieving low gray scale brightness, DC dimming has a problem of strobing and eye damage.
Embodiments of the present application provide a pixel circuit, a driving method therefor, and a display device.
In a first aspect, the embodiments of the present application provide a pixel circuit, including: a current control circuit, a duration control circuit and a light-emitting element; the current control circuit is configured for receiving a data signal and a first scan signal, and controlling an amplitude of a generated drive current according to the data signal and the first scan signal; and
In some exemplary embodiments, the duration control circuit includes: a duration selection sub-circuit, a first duration control sub-circuit, a second duration control sub-circuit, and a light-emitting control circuit.
The duration selection sub-circuit is connected with a first voltage end, a mode control signal end, a second scan signal end, a third scan signal end, a first node and a second node respectively, and is configured for writing the mode control signal into the first node and the second node under control of the mode control signal, a second scan signal outputted by the second scan signal end and a third scan signal outputted by the third scan signal end.
The first duration control sub-circuit is connected with the first node, a third node and a pulse control signal end respectively, and is configured for writing a pulse control signal of the pulse control signal end into the third node under control of a signal of the first node.
The second duration control sub-circuit is connected with the second node, the third node and a light-emitting control signal end respectively, and is configured for writing, when the mode control signal is in a second mode, a light-emitting control signal of the light-emitting control signal end into the third node under control of a signal of the second node.
And, the light-emitting control circuit is connected with the third node, the first voltage end, the light-emitting control signal end, a first scan signal end, and the current control circuit respectively, and is configured for receiving the drive current, and controlling a duration of the drive current flowing through the light-emitting element under control of a signal of the third node, the light-emitting control signal outputted by the light-emitting control signal end, and the first scan signal outputted by the first scan signal end.
In some exemplary embodiments, the duration selection sub-circuit includes a first duration selection sub-circuit and a second duration selection sub-circuit;
In some exemplary embodiments, the light-emitting control circuit is connected with the current control circuit, the third node and the first voltage end respectively, and is configured for receiving the drive current, and controlling the duration of the drive current flowing through the light-emitting element under the control of the signal of the third node.
In some exemplary embodiments, the first duration control sub-circuit includes a first transistor; a control electrode of the first transistor is connected with the first node, a first electrode of the first transistor is connected with the pulse control signal end, and a second electrode of the first transistor is connected with the third node.
In some exemplary embodiments, the second duration control sub-circuit includes a second transistor; a control electrode of the second transistor is connected with the second node, a first electrode of the second transistor is connected with the light-emitting control signal end, and a second electrode of the second transistor is connected with the third node.
In some exemplary embodiments, the first duration selection sub-circuit includes a first capacitor and a third transistor;
In some exemplary embodiments, the second duration selection sub-circuit includes a second capacitor and a fourth transistor;
In some exemplary embodiments, the light-emitting control circuit includes a fifth transistor; a control electrode of the fifth transistor is connected with the third node, a first electrode of the fifth transistor is connected with the current control circuit, and a second electrode of the fifth transistor is connected with the first voltage end.
In some exemplary embodiments, the current control circuit includes: a data writing circuit, a storage circuit and a drive circuit; the data writing circuit is configured for writing a data signal outputted by a data signal end into a fourth node under control of the first scan signal; the storage circuit is configured for storing electric energy at the fourth node; and the drive circuit is configured for generating a drive current under control of a signal of the fourth node.
In some exemplary embodiments, the data writing circuit includes an eighth transistor, the storage circuit includes a third capacitor, and the drive circuit includes a drive transistor;
In some exemplary embodiments, the pixel circuit further includes an external compensation circuit, and the external compensation circuit is configured for compensating a threshold voltage.
In some exemplary embodiments, the external compensation circuit includes a sixth transistor, a seventh transistor and a ninth transistor;
In a second aspect, an embodiment of the present application further provides a display device, including any above pixel circuit.
In a third aspect, an embodiment of the present application further provides a driving method of a pixel circuit, for driving any above pixel circuit described in the first aspect, the pixel circuit includes a plurality of scanning cycles, and within one scanning cycle, the driving method includes:
Beneficial effects:
Drawings are used to provide an understanding of technical solutions of the present application, constitute a part of the specification, and are used to explain the technical solutions of the present application together with embodiments of the present application, which do not constitute a limitation on the technical solutions of the present application.
In order to make objectives, technical solutions and advantages of the present application clearer and more understandable, embodiments of the present application will be described in detail below with reference to accompanying drawings. It should be noted that the embodiments in the present application and features in the embodiments may be arbitrarily combined with each other in the case of not conflict.
Unless otherwise defined, technical or scientific terms publicly used in the embodiments of the present application shall have the ordinary meanings understood by those ordinarily skilled in the art to which the present application pertains. Words “first”, “second” and the like used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words “comprise” or “include” and the like indicate that an element or item appearing before such the word covers listed elements or items appearing after the word and equivalents thereof, and does not exclude other elements or items.
Those skilled in the art may understand that transistors used in all the embodiments of the present application may be thin film transistors or field-effect transistors, or other devices with similar characteristics. Preferably, the thin film transistors used in the embodiments of the present application may be oxide semiconductor transistors. Since sources and drains of the transistors used here are symmetrical, their sources and drains may be interchanged. In the embodiments of the present application, in order to distinguish two electrodes of the transistors except for gates, one of the electrodes is called a first electrode, the other electrode is called a second electrode, the first electrode may be the source, and the second electrode may be the drain.
The pixel circuit, the driving method therefor, and the display device provided by the present application at least can enable the light emitting diode to accurately present the low gray scale brightness. The pixel circuit, the driving method therefor, and the display device provided by the embodiments of the present application are described in detail below.
As shown in
The current control circuit 301 is connected with a data signal end DI and a first scan signal end GA, and is configured for receiving a data signal DI and a first scan signal gataA, and controlling, under an action of the first scan signal gataA, an amplitude of a drive current according to an amplitude of the data signal DI.
The duration control circuit 302 is connected with a mode control signal end DT, a pulse control signal end Hf, and a light-emitting control signal end EM_B, and is configured for receiving a mode control signal DT, a pulse control signal hf, a light-emitting control signal em_b and a drive current of the current control circuit, and controlling a length of time for providing the light-emitting element 303 with the drive current according to an amplitude of the mode control signal DT.
The pixel circuit provided by the embodiments of the present application may control the length of time for providing the light-emitting element with the drive current within each scanning cycle. For example, the pulse control signal hf provided by the pulse control signal end Hf includes a plurality of valid time periods in a light-emitting stage, and the valid time periods refer to time periods that enable the light-emitting element to be in a current path state. In the light-emitting stage, the valid pulse time periods included by the pulse control signal hf form a first duration, a duration of the light-emitting stage is a second duration, and the first duration is much smaller than the second duration. By setting the amplitude of the data signal DI provided by the data signal end DI, the light-emitting element can work in a current path with a large amplitude, which ensures that the light-emitting element has high uniformity of the emission brightness, high light-emitting efficiency and stable chromaticity coordinates. In a case of achieving high gray scale brightness, the length of time for providing the light-emitting element with the drive current is the second duration, and in a case of achieving low gray scale brightness, the length of time for providing the light-emitting element with the drive current is the first duration. Taking 256 gray scales as an example for illustration, for example, a range of high gray scale brightness is from 80 gray scales to 255 gray scales, then when achieving the 80-255 gray scales, the length of time for providing the light-emitting element with the drive current is the second duration, and the corresponding gray scale brightness is achieved by setting the amplitude of different data signals DI provided by the data signal end DI. For a range of low gray scale of 0-79 gray scales, the length of time for providing the light-emitting element with the drive current is the first duration, and meanwhile, the corresponding gray scale brightness is achieved by setting the amplitude of different data signals DI provided by the data signal end DI. It may be understood that when achieving the high gray scale brightness and the low gray scale brightness, there is overlapping in the amplitude range of the data signal DI provided by the data signal end DI, so as to ensure that the light-emitting element has high uniformity of emission brightness, high light-emitting efficiency and stable chromaticity coordinates.
In some exemplary embodiments, as shown in
The duration selection sub-circuit 3021 is connected with a first voltage end LVSS, a mode control signal end DT, a second scan signal end GH, a third scan signal end GE, a first node N1 and a second node N2, and is configured for writing the mode control signal into the first node N1 and the second node N2 under the control of the mode control signal DT, a second scan signal GH outputted by the second scan signal end and a third scan signal GE outputted by the third scan signal end.
The first duration control sub-circuit 3022 is connected with the first node N1, a third node N3 and a pulse control signal end Hf, and is configured for writing a pulse control signal hf of the pulse control signal end Hf into the third node N3 under the control of a signal of the first node N1.
The second duration control sub-circuit 3023 is connected with the second node N2, the third node N3 and a light-emitting control signal end EM_B, and is configured for writing a light-emitting control signal em_b of the light-emitting control signal end EM_B into the third node N3 under control of a signal of the second node N2.
The light-emitting control circuit 3024 is connected with the third node N3, the first voltage end LVSS, the light-emitting control signal end EM_B, the first scan signal end GA and the current control circuit, and is configured for receiving the drive current, and controlling a duration of the drive current flowing through the light-emitting element under the control of a signal of the third node N3, the light-emitting control signal em_b outputted by the light-emitting control signal end EM_B, and the first scan signal gataA outputted by the first scan signal end GA.
In some exemplary embodiments, as shown in
In some exemplary embodiments, as shown in
A control electrode of the first transistor M1 is connected with the first node N1, a first electrode of the first transistor M1 is connected with the pulse control signal end, and a second electrode of the first transistor M1 is connected with the third node N3; a control electrode of the second transistor M2 is connected with the second node N2, a first electrode of the second transistor M2 is connected with the light-emitting control signal end, and a second electrode of the second transistor M2 is connected with the third node N3; a control electrode of the third transistor M3 is connected with the second scan signal end, a first electrode of the third transistor M3 is connected with the mode control signal end, and a second electrode of the third transistor M3 is connected with the first node N1; a first end of the first capacitor C1 is connected with the first voltage end, and a second end of the first capacitor C1 is connected with the first node N1; a control electrode of the fourth transistor M4 is connected with the third scan signal end, a first electrode of the fourth transistor M4 is connected with the mode control signal end, and a second electrode of the fourth transistor M4 is connected with the second node N2; a first end of the second capacitor C2 is connected with the first voltage end, and a second end of the second capacitor C2 is connected with the second node N2; and a control electrode of the fifth transistor is connected with the third node N3, a first electrode of the fifth transistor M5 is connected with the current control circuit, and a second electrode of the fifth transistor M5 is connected with the first voltage end.
In some exemplary embodiments, as shown in
As shown in
In some exemplary embodiments, as shown in
As shown in
It is easy for those skilled in the art to understand that implementation methods of all above circuits are not limited to this, as long as their respective functions can be achieved.
In some exemplary embodiments, as shown in
In some exemplary embodiments, the light-emitting element may be a mini light emitting diode (Mini LED), a micro light emitting diode (Micro LED), or other types of light emitting diodes, such as an organic light emitting diode (OLED), and a quantum dot light emitting diode (QLED). In practical applications, the structure of the light-emitting element 303 needs to be designed and determined according to the practical application environment, which is not limited here. The light-emitting element 303 being the micro light emitting diode is taken as an example for illustration below.
In some exemplary embodiments, the first transistor M1 to the ninth transistor M9, and the drive transistor Md may be N-type transistors or P-type transistors, and the embodiments of the present application takes the N-type transistor as an example for illustration.
In some exemplary embodiments, all transistors in the embodiments of the present application may be the N-type transistors, and specifically, active layer materials of the transistors may be low-temperature poly-silicon or metal oxides.
In some exemplary embodiments, a pulse control signal Hf outputted by a pulse control signal end Hf may be generated by an external integrated circuit (IC).
In some exemplary embodiments, as shown in
It may be understood that the first scan signal end GA, the second scan signal end GH, the third scan signal end GE and the fourth scan signal end GB of each pixel circuit corresponding to a row of sub-pixels are coupled to a same first scan signal lines GL1, a same second scan signal lines GL2, a same third scan signal lines GL3 and a same fourth scan signal lines GL4, respectively; the mode control signal end DT, the data signal end DI and the threshold voltage output end Rdout of each pixel circuit corresponding to a column of sub-pixels are coupled to a same first data signal lines DL1, a same second data signal lines DL2 and a same compensation voltage control lines RL, respectively; and the light-emitting control signal line E1, the pulse control signal line E2, the first voltage line LV1 and the second voltage line LV2 are shared signal lines, which are respectively coupled to the light-emitting control signal ends EM_B, the pulse control signal ends Hf, the first voltage ends LVSS and the second voltage ends LVDD of all the pixel circuits.
In the first stage T1, as shown in
In the second stage T2, as shown in
In the third stage T3, the second scan signal GH outputted by the second scan signal end GH is a low level signal, the third scan signal GE outputted by the third scan signal end GE is a low level signal, a first scan signal gataA outputted by a first scan signal end GA is a high level signal, an eighth transistor M8 is turned on, and a data signal DI provided by a data signal end DI is written and stored into a fourth node N4, namely a gate of a drive transistor Md.
In the fourth stage T4, namely a light-emitting stage, the first scan signal gataA outputted by the first scan signal end GA is changed into a low level signal, a seventh transistor M7 and the eighth transistor M8 are turned off, and a fifth transistor M5 controls a length of time for providing the light-emitting element with the drive current according to a potential of a third node N3. In some embodiments, as shown in
Exemplarily, the pulse control signal hf in the embodiments of the present application is a high-frequency pulse signal, for example, a frequency of the pulse control signal hf may be taken values from 3000 Hz-60000 Hz, such as 3000 Hz or 60000 Hz; and a frequency of the light-emitting control signal em_b may be taken values from 60 Hz-120 Hz, such as 60 Hz or 120 Hz.
Based on the above steps, by setting the amplitude of the data signal DI provided by the data signal end DI, the light-emitting element can work in a current path with a large amplitude, which ensures that the light-emitting element has high uniformity of the emission brightness, high light-emitting efficiency and stable chromaticity coordinates. In the case of achieving the high gray scale brightness, the length of time for providing the light-emitting element with the drive current is a second duration; and in the case of achieving the low gray scale brightness, the length of time for providing the light-emitting element with the drive current is a first duration. In this way, the drive current with high amplitude can be matched with short light-emitting time to achieve the display of low gray scale brightness, so that the display effect of the display device at low gray scale can be improved.
In some embodiments, the pixel circuit provided by the embodiments of the present application may further include a threshold voltage Vth reading stage in addition to the above stage T1, stage T2, stage T3 and stage T4 during working. For example, as shown in
In an initial stage (Initial), a first scan signal gataA provided by the first scan signal end GA and a fourth scan signal GB provided by the fourth scan signal end GB are both high level signals, the eighth transistor M8 and a ninth transistor M9 are turned on, a switch Sw_ref is closed, and the node N5 and the threshold voltage output end Rdout are set to be 0 V by an external power supply, so as to achieve potential initialization.
In a threshold voltage output stage, the first scan signal gataA provided by the first scan signal end GA and the fourth scan signal GB provided by the fourth scan signal end GB are high level signals, while a light-emitting control signal em_b provided by a light-emitting control signal end EM_B and a pulse control signal hf provided by a pulse control signal end are both low level signals, the eighth transistor M8 and the ninth transistor M9 are turned on, the switch Sw_ref is disconnected, a fifth transistor M5 and a sixth transistor M6 are turned off, a second electrode (namely the fifth node N5) of the drive transistor Md is charged to (Vdata-Vth), and a potential of the fifth node N5 is transmitted to the threshold voltage output end Rdout through the ninth transistor M9.
In a threshold voltage reading sampling stage (Sampling), Sw_samp is closed to transmit the potential (Vdata-Vth) stored at the threshold voltage output end Rdout to an external chip, and Vth is extracted. Therefore, at the third stage T3 in the scanning cycle after the Blanking time, Vth may be compensated into a data signal DI provided by a data signal end DI, so that the amplitude of the drive current is unrelated to the threshold voltage Vth of the drive transistor Md, that is, the threshold voltage Vth of the drive transistor Md is prevented from affecting the amplitude of the drive current provided to the light-emitting element.
It may be understood that within the Blanking time, the pulse control signal end Hf provides a low level signal, so as to ensure the accurate reading of the threshold voltage Vth of the drive transistor Md.
In some embodiments, the pixel circuit may further adopt an internal compensation mode to eliminate the effect of the threshold voltage Vth of the drive transistor Md on the amplitude of the drive current. For example, before the third stage T3 in the scanning cycle, the drive transistor Md may be charged to a saturation region, which is not limited here. The embodiments of the present application further provide a display device, the display device includes a plurality of sub-pixels arranged in an array, and each sub-pixel includes the pixel circuit described in any of the above embodiments. The display device of the embodiments of the present disclosure may be any product or component with a display function, such as a mobile phone, a tablet, a television, a display, a laptop, a digital photo frame and a navigator.
Based on the same inventive concept, the embodiments of the present application further provide a driving method of a pixel circuit, used for driving the pixel circuit as mentioned above, the pixel circuit has a plurality of scanning cycles, and within one scanning cycle, as shown in
S1700, a current control circuit receives a data signal and a first scan signal, and controls an amplitude of a generated drive current according to the data signal and the first scan signal.
S1701, a duration control circuit receives a mode control signal, a pulse control signal, a light-emitting control signal and the drive current of the current control circuit, and controls a length of time for providing a light-emitting element with the drive current according to an amplitude of the mode control signal.
According to the pixel circuit, the driving method therefor, and the display device provided by the embodiments of the present application, by setting the amplitude of the data signal DI provided by the data signal end DI, the light-emitting element can work in a current path with a large amplitude, which ensures that the light-emitting element has high uniformity of the emission brightness, high light-emitting efficiency and stable chromaticity coordinates. In the case of achieving the high gray scale brightness, the length of time for providing the light-emitting element with the drive current is the second duration; and in the case of achieving the low gray scale brightness, the length of time for providing the light-emitting element with the drive current is the first duration. In this way, the drive current with high amplitude can be matched with short light-emitting time to achieve the display of the low gray scale brightness, so that the display effect of the display device at the low gray scale can be improved.
There are several points needing to be clarified below.
The drawings of the embodiments of the present application only relate to the structures involved in the embodiments of the present application, and other structures may refer to the usual design.
Without conflict, the embodiments of the present application, namely features in the embodiments may be combined with each other to obtain new embodiments.
Although the implementations disclosed in the present application are as described above, the content described is only implementations adopted for the convenience of understanding the present application, and is not intended to limit the present application. Any skilled in the art to which the present application belongs may make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present application. However, the scope of patent protection of the present application shall still be subject to the scope defined in the attached claims.
This application is a national phase entry under 35 U.S.C § 371 of International Application No. PCT/CN2021/120479, filed on Sep. 24, 2021, the entire content of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2021/120479 | 9/24/2021 | WO |
