Patent Grant
10977984
This application claims priority to Chinese Patent Application No. 201810820707.5, filed on Jul. 24, 2018, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to the field of display technology, and particularly, to a pixel circuit and a method for driving the same, a display panel and a video wall.
Compared to organic light emitting diodes (OLEDs), light emitting diodes have advantages such as high current-resistance, high brightness or the like and can be applied in display applications such as outdoor display, large display or the like.
The main peak of the emission spectrum of the LEDs may undergo offsets under different currents. Therefore, the pulse-width modulation (PWM) method is generally employed to perform passive matrix (PM) driving on the existing LED displays or LEDs.
In an aspect, the present disclosure provides a pixel circuit, including a light emitting diode having a first electrode configured to receive a first power supply voltage and a second electrode configured to receive a second power supply voltage; and a switching sub-circuit having a first terminal electrically coupled to a display signal terminal, a second terminal electrically coupled to the second electrode of the light emitting diode and a control terminal electrically coupled to a scan signal terminal, and configured to control an emission state of the light emitting diode based on a display signal provided from the display signal terminal, in response to a scan signal provided from the scan signal terminal, wherein the emission state varies based on a magnitude and a duration of an effective voltage level of the display signal.
In some embodiments, the switching sub-circuit includes a switching transistor having a first electrode electrically coupled to the display signal terminal, a second electrode electrically coupled to the second electrode of the light emitting diode and a control electrode electrically coupled to the scan signal terminal.
In some embodiments, the pixel circuit further includes an emission control sub-circuit having a first terminal electrically coupled to the second electrode of the light emitting diode, a second terminal electrically coupled to a second power supply voltage terminal and a control terminal electrically coupled to the second terminal of the switching sub-circuit, and configured to couple a voltage provided from the second power supply voltage terminal as the second power supply voltage to the second electrode of the light emitting diode in response to the display signal.
In some embodiments, the emission control sub-circuit includes an emission control transistor having a first electrode electrically coupled to the second electrode of the light emitting diode, a second electrode electrically coupled to the second power supply voltage terminal and a control electrode electrically coupled to the second terminal of the switching sub-circuit.
In some embodiments, the pixel circuit further includes a reset sub-circuit having a first terminal electrically coupled to a restoration signal terminal, a second terminal electrically coupled to the second electrode of the light emitting diode and a control terminal electrically coupled to a reset signal terminal, and configured to couple a restoration signal provided from the restoration signal terminal to the second electrode of the light emitting diode in response to a reset signal provided from the reset signal terminal.
In some embodiment, the reset sub-circuit includes a reset transistor having a first electrode electrically coupled to the restoration signal terminal, a second electrode electrically coupled to the second electrode of the light emitting diode and a control electrode electrically coupled to the reset signal terminal.
In some embodiments, the light emitting diode is a mini light emitting diode.
In some embodiments, the first power supply voltage has a fixed high voltage level, and the second power supply voltage has a fixed low voltage level.
In another aspect, the present disclosure provides a method for driving a pixel circuit including a light emitting diode having a first electrode configured to receive a first power supply voltage and a second electrode configured to receive a second power supply voltage and a switching sub-circuit having a first terminal electrically coupled to a display signal terminal, a second terminal electrically coupled to the second electrode of the light emitting diode and a control terminal electrically coupled to a scan signal terminal, the method including turning on the switching sub-circuit through a scan signal provided from the scan signal terminal and controlling an emission state of the light emitting diode based on a display signal provided from the display signal terminal, wherein the emission state varies based on a magnitude and a duration of an effective voltage level of the display signal.
In some embodiments, the pixel circuit further includes an emission control sub-circuit having a first terminal electrically coupled to the second electrode of the light emitting diode, a second terminal electrically coupled to a second power supply voltage terminal and a control terminal electrically coupled to the second terminal of the switching sub-circuit, and controlling the emission state of the light emitting diode based on the display signal provided from the display signal terminal includes controlling a duration during which the emission control sub-circuit is in on state based on the display signal to control the emission state of the light emitting diode.
In some embodiments, the pixel circuit further includes a reset sub-circuit having a first terminal electrically coupled to a restoration signal terminal, a second terminal electrically coupled to the second electrode of the light emitting diode and a control terminal electrically coupled to a reset signal terminal, and the method further includes: turning on the reset sub-circuit through a reset signal provided from the reset signal terminal and coupling a restoration signal provided from the restoration signal terminal to the second electrode of the light emitting diode to reset the light emitting diode.
In some embodiments, the light emitting diode is a mini light emitting diode.
In some embodiments, the first power supply voltage has a fixed high voltage level, and the second power supply voltage has a fixed low voltage level.
In another aspect, the present disclosure further provides a pixel circuit, including a switching transistor, an emission control transistor, a reset transistor and a light emitting diode, wherein the switching transistor has a first electrode electrically coupled to a display signal terminal, a second electrode electrically coupled to a second electrode of the light emitting diode and a control electrode electrically coupled to a scan signal terminal; the emission control transistor has a first electrode electrically coupled to the second electrode of the light emitting diode, a second electrode electrically coupled to a second power supply voltage terminal and a control electrode electrically coupled to the second electrode of the switching transistor; the reset transistor has a first electrode electrically coupled to a restoration signal terminal, a second electrode electrically coupled to the second electrode of the light emitting diode and a control electrode electrically coupled to a reset signal terminal; and the light emitting diode has a first electrode electrically coupled to a first power supply voltage terminal and the second electrode electrically coupled to the first electrode of the emission control transistor and the second electrode of the reset transistor, wherein the switching transistor is configured to control an emission state of the light emitting diode based on a display signal provided from the display signal terminal, in response to a scan signal provided from the scan signal terminal, and wherein the emission state varies based on a magnitude and a duration of an effective voltage level of the display signal.
In some embodiments, the emission control transistor is configured to couple a voltage provided from the second power supply voltage terminal as a second power supply voltage to the second electrode of the light emitting diode in response to the display signal.
In some embodiments, the reset transistor is configured to couple a restoration signal provided from the restoration signal terminal to the second electrode of the light emitting diode in response to a reset signal provided from the reset signal terminal.
In another aspect, the present disclosure further provides a display panel, including a plurality of scan lines and a plurality of display signal lines intersecting each other, and a plurality of pixel units defined by intersections of the plurality of scan lines and the plurality of display signal lines, the plurality of pixel units being arranged in an array having rows and columns, and each of the plurality of pixel units having a pixel circuit provided therein, wherein the pixel circuit is any one of the pixel circuits described herein, wherein switching sub-circuits of a same row of pixel circuits of the plurality of pixel units are electrically coupled to a same scan line of the plurality of scan lines, and switching sub-circuits of a same column of pixel circuits of the plurality of pixel units are electrically coupled to a same display signal line of the plurality of display signal lines.
In some embodiments, the display panel further includes a glass substrate, and pixel circuits of the plurality of pixel units are provided on the glass substrate.
In some embodiments, the light emitting diode is a mini light emitting diode.
In another aspect, the present disclosure further provides a video wall formed by a plurality of display panels spliced together, wherein each of the plurality of display panels is any one of the display panels described herein.
To make those skilled in the art better understand the technical solutions of the present disclosure, the present disclosure will be described in detail below in conjunction with accompanying drawings and specific embodiments.
The main peak of the emission spectrum of the LEDs may undergo offsets under different currents. Therefore, the pulse-width modulation (PWM) method is generally employed to perform passive matrix (PM) driving on the existing LED displays or LEDs. However, when the PM driving is applied to a display having high resolution and large size, a large number of signal lines are required, such that the narrow bezel design of the display panel can hardly be achieved.
Accordingly, the present disclosure provides, inter alia, a pixel circuit and a method for driving the same, a display panel and a video wall that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.
The transistor as described herein may refer to a thin film transistor or a field-effect transistor or other devices having similar characteristics. As the source and the drain of the employed transistor may be exchangeable in certain conditions, the descriptions in terms of the connection relationships are identical for the source and the drain. In embodiments of the present discourse, to distinguish the source and the drain of the transistor, one of them may be referred to as a first electrode and the other one may be referred to as a second electrode and the gate may be referred to as a control electrode. In addition, the transistors may be classified into an N-type transistor or a P-type transistor according to their characteristics. In the following embodiments, the transistor is described as a P-type transistor as an example. In a case where a P-type transistor is employed, the first electrode of the P-type transistor may be the source of the P-type transistor, the second electrode of the P-type transistor may be the drain of the P-type transistor, and the source and the drain are electrically connected when the gate of the P-type transistor receives a low voltage level, reverse rules apply to the N-type transistor. It is conceivable that embodiments in which the transistor is an N-type transistor are readily conceived by those skilled in the art without any creative efforts, and thus belong to the protection scope of the present disclosure.
The light emitting diode employed in the embodiments of the present disclosure may be a mini light emitting diode (mini LED). One of the first and second electrodes of the light emitting diode is a cathode and the other one is an anode. In the embodiments of the present disclosure, the descriptions are made by taking that the first electrode is an anode and the second electrode is a cathode as an example.
In an aspect, the present disclosure provides a pixel circuit.
In the present disclosure, the term “electrically coupled to” may refer to one element being directly coupled to another element (i.e., there is no intermediate element between the two elements) or one element being indirectly coupled to another element (i.e., there is an intermediate element intervening between the two elements).
The present pixel circuit includes the switching sub-circuit 1, when the present pixel circuit is applied to a display panel including pixel circuits in rows and columns, (the scan signal terminals of) the switching sub-circuits 1 of a same row of pixel circuits may be electrically coupled to a same scan line and (the display signal terminals of) the switching sub-circuits 1 of a same column of pixel circuits may be electrically coupled to a same display signal line. As such, the switching sub-circuits in a same row of pixel circuits are controlled to be turned on by progressively inputting scan signals to the scan lines, and then the emission state of the light emitting diode D1 in the pixel circuit coupled to a display signal line is controlled based on the display signal input to the display signal line. Compared to the driving manner of the light emitting diodes in the existing display panel, the wirings can be reduced by applying the present pixel circuit in the display panel, such that the narrow bezel design of the display panel can be achieved. Further, the display panel using the present pixel circuit can be applied to a video wall, thereby achieving a panel having large size and high resolution.
The present pixel circuit may be driven by employing the following driving method including: turning on the switching sub-circuit 1 through a scan signal and controlling the emission state of the light emitting diode D1 based on a display signal input to the switching sub-circuit 1.
In some embodiments, as illustrated in
In an example, when a low voltage level signal is input to the scan signal terminal Gate, the switching transistor T1 is turned on. At this time, the display signal input to the display signal terminal DP can be input to the second electrode of the light emitting diode D1, that is, the display signal is used as the second power supply voltage to control the light emitting diode D1 to emit light. Meanwhile, a timing control sub-circuit (not shown in figures) may be used to control the duration of the effective voltage level of the display signal, and the magnitude of the effective voltage level of the display signal may be controlled, so as to control the brightness and the grayscale displayed by the light emitting diode. As used herein, the term “effective voltage level” may refer to a voltage level enabling the light emitting diode D1 to emit light, or may refer to a voltage level turning on the transistor as described later.
In a case where the pixel circuit includes the emission control sub-circuit 2, the method for driving the pixel circuit may further include controlling a duration during which the emission control sub-circuit 2 is in on state based on the display signal to control the emission state of the light emitting diode D1.
As illustrated in
As illustrated in
In a case where the pixel circuit includes the reset sub-circuit 3, the method for driving the pixel circuit may further include turning on the reset sub-circuit 3 through a reset signal provided from the reset signal terminal DN and resetting the light emitting diode D1 through a restoration signal provided from the restoration signal terminal VGH.
In some embodiments, as illustrated in
Accordingly, the pixel circuit further includes the first power supply voltage terminal VDD configured to provide a first power supply voltage and electrically coupled to the first electrode of the light emitting diode D1. In this case, when the first power supply voltage received from the first power supply voltage terminal VDD is higher than the second power supply voltage received from the second power supply voltage terminal VSS, the light emitting diode D1 may emit light. Optionally, the first power supply voltage has a fixed high voltage level, and the second power supply voltage has a fixed low voltage level.
Next, the pixel circuit according to an embodiment of the present disclosure will be described in detail with reference to
The pixel circuit includes the switching transistor T1, the emission control transistor T2, the reset transistor T3 and the light emitting diode D1, when the present pixel circuit is applied to a display panel including pixel circuits in rows and columns, the control electrodes of the switching transistor T1 of a same row of pixel circuits may be electrically coupled to a same scan line, the first electrodes of the switching transistor T1 of a same column of pixel circuits may be electrically coupled to a same display signal line, the control electrodes of the reset transistors T3 of a same row of pixel circuits may be electrically coupled to a same reset signal line, and first electrodes of reset transistors T3 of a same column of pixel circuits may be electrically coupled to a same restoration signal line. As such, the switching transistors T1 in a same row of pixel circuits are controlled to be turned on by progressively inputting scan signals to the scan lines, and the emission state of the light emitting diode D1 in the pixel circuit coupled to a display signal line is controlled based on the display signal input to the display signal line. Similarly, the reset transistors T3 in a same row of pixel circuits may be controlled to be turned on by progressively inputting reset signals to the reset signal lines, and the light emitting diode D1 coupled to a restoration signal line is restored through the restoration signal input to the restoration signal line so as not to emit light. Compared to the driving manner of the light emitting diodes in the existing display panel, the wirings can be reduced by applying the present pixel circuit in the display panel, such that the narrow bezel design of the display panel can be achieved. Further, the display panel using present pixel circuit can be applied to a video wall, thereby achieving a panel with large size and high resolution.
In the reset stage (t1), a low voltage level signal is input to the reset signal terminal DN, the reset transistor T3 is turned on, and the restoration signal (which is a high voltage level signal and higher than the first power supply voltage applied to the first electrode of the light emitting diode D1) input to the restoration signal terminal VGH is transmitted to the second electrode of the light emitting diode D1 to cause the light emitting diode D1 not to emit light.
In the emission stage (t2), a low voltage level signal is input to the scan signal terminal Gate, the switching transistor T1 is turned on, and a low voltage level signal input to the display signal terminal DP is transmitted to the control electrode of the emission control transistor T2. At this time, the emission control transistor T2 is turned on and the second power supply voltage from the second power supply voltage terminal VSS is transmitted to the second electrode of the light emitting diode D1. As such, the light emitting diode D1 emits light under the control of the voltage difference between the first power supply voltage and the second power supply voltage (which is lower than the first power supply voltage). In some embodiments, by setting a relatively large voltage difference between the first power supply voltage and the second power supply voltage, a relatively high brightness can be achieved.
In the reset stage (t1), a low voltage level signal is input to the reset signal terminal DN, the reset transistor T3 is turned on, and the restoration signal (which is a high voltage level signal and higher than the first power supply voltage applied to the first electrode of the light emitting diode D1) input to the restoration signal terminal VGH is transmitted to the second electrode of the light emitting diode D1 to cause the light emitting diode D1 not to emit light.
In the emission stage (t2), a high voltage level signal is input to the reset signal terminal DN, the reset transistor T3 is turned off, and at the same time a low voltage level signal is input to the scan signal terminal Gate, the switching transistor T1 is turned on, and a low voltage level signal from the display signal terminal DP is transmitted to the control electrode of the emission control transistor T2 through the switching transistor T1. At this time, the emission control transistor T2 is turned on, and the second the second power supply voltage from the second power supply voltage terminal VSS is transmitted to the second electrode of the light emitting diode D1. As such, the light emitting diode D1 emits light under the control of the voltage difference between the first power supply voltage and the second power supply voltage (which is lower than the first power supply voltage). In some embodiments, by setting a relatively large voltage difference between the first power supply voltage and the second power supply voltage, a relatively high brightness can be achieved.
In the L0 grayscale maintain stage (t3), a low voltage level is input to the scan signal terminal Gate, and the emission control transistor T2 is turned off as a high voltage level signal is input to the display signal terminal DP. Meanwhile, a low voltage level signal is input to the reset signal terminal DN, so that the restoration signal input to the restoration signal terminal VGH is transmitted to the second electrode of the light emitting diode D1 to ensure that the light emitting diode D1 is reversely biased and does not emit light.
As described above, the duration (i.e., effective time) of the effective voltage level of the display signal may be controlled by the timing control sub-circuit, and the magnitude of the effective voltage level of the display signal may be controlled (e.g., by a controller), so as to control the displayed brightness and grayscale of the light emitting diode D1. Here, by controlling the pulse width (i.e., effective time) of the low voltage level signal input from the display signal terminal DP in the emission stage, different grayscales of the light emitting diode D1 can be achieved. It has been discovered in the present disclosure that there is a correspondence between the effective time (microsecond (μs)) and the grayscales of L1 to L256. In addition, to achieve the grayscale of L0 of the light emitting diode D1, the display signal input from the display signal terminal DP in the emission stage may be controlled to be at a high voltage level, such that the emission control transistor T2 is turned off. At the same time, the reset signal terminal DN is controlled to input a low voltage level signal to turn on the reset transistor T3 and then a high voltage level signal input to the restoration signal terminal VGH is transmitted to the second electrode of the light emitting diode D1, such that the light emitting diode D1 is reversely biased and does not emit light.
As shown in Table 1, the pulse width (i.e., effective time) of the low voltage level signal input from the display signal terminal DP in the emission stage corresponds to the grayscale. For example, the longer the effective time, the higher the grayscale, and the shorter the effective time, the lower the gray scale. For example, in a case where the effective time is 0.01 μs, the grayscale of L1 can be achieved, and in a case where the effective time is 2222 μs, the grayscale of L256 can be achieved.
In another aspect, the present disclosure provides a display panel.
In addition, as illustrated in
In the present display panel, the switching sub-circuits 1 of a same row of pixel circuits are electrically coupled to a same scan line and the switching sub-circuits 1 of a same column of pixel circuits are electrically coupled to a same display signal line. As such, the switching sub-circuits in a same row of pixel circuits are controlled to be turned on by progressively inputting scan signals to the scan lines, and the emission state of the light emitting diode D1 in the pixel circuit coupled to a display signal line is controlled based on the display signal input to the display signal line. Compared to the driving manner of the light emitting diodes in the existing display panel, the wirings can be reduced in the present display panel including the pixel circuits described herein, such that the narrow bezel design of the display panel can be achieved.
The pixel circuit in the present display panel may further include the reset sub-circuit 3. The reset sub-circuits 3 in a same row of pixel circuits are electrically coupled to a same reset signal line (e.g., DN1) and the reset sub-circuits 3 in a same column of pixel circuits are electrically coupled to a same restoration signal line (represented by VGH in
From
The display signals applied to the display signal lines (DP1 to DPm), which are schematically illustrated in
In another aspect, the present disclosure further provides a video wall including a plurality of display panels, each of which is any one of the display panels described herein. The plurality of display panels are spliced together to form the video wall. By splicing the plurality of display panels together, a large size panel with a high resolution can be realized and the wirings thereof is less.
The display panel may include a product or part having display function such as an OLED panel, a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator or the like.
It is to be understood that the above embodiments are merely exemplary embodiments for the purpose of explaining the principles of the present disclosure, but the present disclosure is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the present disclosure. These modifications and improvements are also considered to be within the protection scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201810820707.5 | Jul 2018 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20070063993 | Shishido | Mar 2007 | A1 |
| 20090021496 | Silzars | Jan 2009 | A1 |
| 20170337874 | Toyomura | Nov 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 1928973 | Mar 2007 | CN |
| 102460550 | May 2012 | CN |
| 103680337 | Mar 2014 | CN |
| 104575398 | Apr 2015 | CN |
| 104700794 | Jun 2015 | CN |
| 106991964 | Jul 2017 | CN |
| 107038989 | Aug 2017 | CN |
| 107039002 | Aug 2017 | CN |
| 207217082 | Apr 2018 | CN |
| Entry |
|---|
| First Office Action dated Dec. 9, 2019 corresponding to Chinese application No. 201810820707.5. |
| Number | Date | Country | |
|---|---|---|---|
| 20200035148 A1 | Jan 2020 | US |
