Bootstrap circuit for pixel display and display panel
阅读说明：本技术 用于像素显示的自举电路及显示面板 (Bootstrap circuit for pixel display and display panel ) 是由 候瑜 黄小骅 康海燕 于 2018-07-11 设计创作，主要内容包括：本申请涉及液晶显示屏领域,提供了一种用于像素显示的自举电路,包括：第一晶体管、第二晶体管、第三晶体管、自举电容和液晶电容；所述第一晶体管的漏极、所述自举电容的一端与所述液晶电容的一端连接于第一参考点,所述第二晶体管的漏极、所述第三晶体管的漏极与所述自举电容的另一端连接于第二参考点；所述第一晶体管的源极输入第一数据信号、所述第二晶体管的源极输入第二数据信号,所述第一晶体管的栅极和所述第二晶体管的栅极输入第一扫描信号；所述第三晶体管的栅极输入第二扫描信号,源极输入共通电压信号,液晶电容的另一端输入共通电压信号。所述电路能够使得电路自身产生比输入电压更高的电压,从而降低像素显示所需的能耗。(The application relates to the field of liquid crystal display screens, and provides a bootstrap circuit for pixel display, which comprises: a first transistor, a second transistor, a third transistor, a bootstrap capacitor, and a liquid crystal capacitor; the drain of the first transistor, one end of the bootstrap capacitor and one end of the liquid crystal capacitor are connected to a first reference point, and the drain of the second transistor, the drain of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point; a first data signal is input to a source electrode of the first transistor, a second data signal is input to a source electrode of the second transistor, and a first scanning signal is input to a grid electrode of the first transistor and a grid electrode of the second transistor; the grid electrode of the third transistor is input with a second scanning signal, the source electrode of the third transistor is input with a common voltage signal, and the other end of the liquid crystal capacitor is input with a common voltage signal. The circuit can enable the circuit to generate a voltage higher than the input voltage, thereby reducing the power consumption required for pixel display.)
1. A bootstrap circuit for a pixel display, comprising: a first transistor, a second transistor, a third transistor, a bootstrap capacitor, and a liquid crystal capacitor;
the drain of the first transistor, one end of the bootstrap capacitor and one end of the liquid crystal capacitor are connected to a first reference point, and the drain of the second transistor, the drain of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point;
a first data signal is input to a source electrode of the first transistor, a second data signal is input to a source electrode of the second transistor, and a first scanning signal is input to a grid electrode of the first transistor and a grid electrode of the second transistor;
a second scanning signal is input to the grid electrode of the third transistor, a common voltage signal is input to the source electrode of the third transistor, and a common voltage signal is input to the other end of the liquid crystal capacitor.
2. The bootstrap circuit for pixel display of claim 1, wherein the liquid crystal capacitor includes a pixel electrode, and a drain of the first transistor, one end of the bootstrap capacitor and the pixel electrode of the liquid crystal capacitor are connected to a first reference point.
3. The bootstrap circuit for pixel display as recited in claim 1, wherein the liquid crystal capacitor includes a common electrode, and the common electrode of the liquid crystal capacitor inputs a common voltage signal.
4. The bootstrap circuit for pixel display as recited in claim 1, wherein the first transistor, the second transistor and the third transistor are all NMOS transistors.
5. A display panel, comprising: the pixel display device comprises a plurality of pixel units and a bootstrap circuit for driving the pixel units to display pixels;
the bootstrap circuit for driving the pixel unit to perform pixel display includes:
a first transistor, a second transistor, a third transistor, a bootstrap capacitor, and a liquid crystal capacitor;
the drain of the first transistor, one end of the bootstrap capacitor and one end of the liquid crystal capacitor are connected to a first reference point, and the drain of the second transistor, the drain of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point;
a first data signal is input to a source electrode of the first transistor, a second data signal is input to a source electrode of the second transistor, and a first scanning signal is input to a grid electrode of the first transistor and a grid electrode of the second transistor;
a second scanning signal is input to the grid electrode of the third transistor, a common voltage signal is input to the source electrode of the third transistor, and a common voltage signal is input to the other end of the liquid crystal capacitor.
6. The display panel according to claim 5, wherein the liquid crystal capacitor comprises a pixel electrode, and a drain of the first transistor, one end of the bootstrap capacitor, and the pixel electrode of the liquid crystal capacitor are connected to a first reference point.
7. The display panel according to claim 5, wherein the liquid crystal capacitor includes a common electrode, and a common voltage signal is input to the common electrode of the liquid crystal capacitor.
Technical Field
The invention relates to the field of liquid crystal display screens, in particular to a bootstrap circuit for pixel display and a display panel.
Background
Liquid Crystal Displays (LCDs) have many advantages such as thin body, power saving, no radiation, and are widely used, for example: liquid crystal televisions, mobile phones, Personal Digital Assistants (PDAs), digital cameras, computer screens, notebook computer screens, or the like, are dominant in the field of flat panel displays.
Most of the liquid crystal displays in the existing market are backlight type liquid crystal displays, which include a housing, a liquid crystal display panel disposed in the housing, and a backlight module disposed in the housing. The liquid crystal display panel is a main component of the liquid crystal display, but the liquid crystal display panel does not emit light, and an image is normally displayed by a light source provided by the backlight module.
Currently, a mainstream liquid crystal display panel is formed by bonding a Thin Film transistor Array (TFT Array Substrate) and a Color Filter (CF) Substrate, and liquid crystal is injected between the TFT Substrate and the CF Substrate. The liquid crystal molecules are controlled to change direction by electrifying or not, and the light rays of the backlight module are refracted out to generate a picture.
The CF substrate comprises a CF substrate and a plurality of pixel units, wherein one side of the CF substrate is provided with the pixel units which are arranged in an array mode, each pixel unit comprises a red sub-pixel, a green sub-pixel and a blue sub-pixel, and a Black Matrix (BM) is distributed on the periphery of each sub-pixel and used for shading light. The area size of the light blocking area corresponding to the three colors of red, green and blue on the CF substrate and the light blocking area corresponding to the black matrix directly affects the aperture ratio and contrast of the liquid crystal display, thereby affecting the overall display quality of the liquid crystal display. The aperture ratio is an important parameter of the liquid crystal display panel, and refers to the ratio of the effective light-transmitting area to the total area of the liquid crystal display panel. When light is emitted from the backlight module, not all light can pass through the liquid crystal display panel: for the TFT substrate, signal traces for the source driver chip and the gate driver chip of the liquid crystal display panel, and a storage capacitor for storing voltage are not completely transparent, and light passing through these places is not controlled by voltage, so that it is necessary to shield the TFT substrate by using a black matrix; for the CF substrate, the light-transmitting area is mainly the light-blocking area corresponding to the red, green and blue sub-pixels, and the black matrix is the light-blocking area, mainly used to prevent the color mixing of the red, green and blue light-blocking of each sub-pixel, so as to increase the contrast value of the panel.
In the liquid crystal display panel, a gate electrode of each TFT switch is connected to a scanning line in a horizontal direction, a source electrode is connected to a data line in a vertical direction, and a drain electrode is connected to a liquid crystal pixel electrode and a storage capacitor. The display screen activates only one gate scan line at a time to turn on the TFT switches of the corresponding row. The data lines in the vertical direction send corresponding video signals to charge the liquid crystal storage capacitor to proper voltage for displaying images of corresponding lines.
In the existing pixel display, when a driving circuit charges a pixel, a power supply voltage is directly transmitted to two ends of a liquid crystal for pixel display, and in the pixel display, the power supply voltage must be larger than the voltage required by liquid crystal deflection, otherwise, the pixel display cannot be realized. Also, to maintain the same output, a larger input voltage needs to be consumed. Therefore, it is necessary to provide a driving circuit and a display panel to realize pixel display with a smaller input voltage.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a bootstrap circuit for pixel display and a display panel. The technical problem to be solved by the invention is realized by the following technical scheme:
the application provides a bootstrap circuit for pixel display, including: a first transistor, a second transistor, a third transistor, a bootstrap capacitor, and a liquid crystal capacitor;
the drain of the first transistor, one end of the bootstrap capacitor and one end of the liquid crystal capacitor are connected to a first reference point, and the drain of the second transistor, the drain of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point;
a first data signal is input to a source electrode of the first transistor, a second data signal is input to a source electrode of the second transistor, and a first scanning signal is input to a grid electrode of the first transistor and a grid electrode of the second transistor;
a second scanning signal is input to the grid electrode of the third transistor, a common voltage signal is input to the source electrode of the third transistor, and a common voltage signal is input to the other end of the liquid crystal capacitor.
In a preferred embodiment, the liquid crystal capacitor includes a pixel electrode, and the drain of the first transistor, one end of the bootstrap capacitor, and the pixel electrode of the liquid crystal capacitor are connected to a first reference point.
In a preferred embodiment, the liquid crystal capacitor includes a common electrode, and the common electrode of the liquid crystal capacitor inputs a common voltage signal.
In a preferred embodiment, the first transistor, the second transistor, and the third transistor are all NMOS transistors.
The present application also provides a display panel, including: the pixel display device comprises a plurality of pixel units and a bootstrap circuit for driving the pixel units to display pixels;
the bootstrap circuit for driving the pixel unit to display the pixel comprises:
a first transistor, a second transistor, a third transistor, a bootstrap capacitor, and a liquid crystal capacitor;
the drain of the first transistor, one end of the bootstrap capacitor and one end of the liquid crystal capacitor are connected to a first reference point, and the drain of the second transistor, the drain of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point;
a first data signal is input to a source electrode of the first transistor, a second data signal is input to a source electrode of the second transistor, and a first scanning signal is input to a grid electrode of the first transistor and a grid electrode of the second transistor;
a second scanning signal is input to the grid electrode of the third transistor, a common voltage signal is input to the source electrode of the third transistor, and a common voltage signal is input to the other end of the liquid crystal capacitor.
In a preferred embodiment, the liquid crystal capacitor includes a pixel electrode, and the drain of the first transistor, one end of the bootstrap capacitor, and the pixel electrode of the liquid crystal capacitor are connected to a first reference point.
In a preferred embodiment, the liquid crystal capacitor includes a common electrode, and the common electrode of the liquid crystal capacitor inputs a common voltage signal.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a bootstrap circuit for pixel display, which realizes the transfer of charges from input to output through the storage effect of a capacitor on the charges, provides current required by a load, and can enable the circuit to generate a voltage higher than an input voltage, thereby realizing the promotion of the voltage.
Further, the circuit generates higher voltage through bootstrap of the capacitor under the condition of keeping the same input voltage, and energy consumption required by pixel display can be reduced.
It is understood that within the scope of the present invention, the above-described technical features of the present invention and the technical features specifically described below (e.g., embodiments and examples) may be combined with each other to constitute new or preferred technical solutions. Not to be reiterated herein, but to the extent of space.
It is further understood that the use of relational terms such as first and second, and the like, in the context of the present invention, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the use of the verb "comprise a" to define an element does not exclude the presence of another, same element in a process, method, article, or apparatus that comprises the element. In the present patent application, if it is mentioned that a certain action is executed according to a certain element, it means that the action is executed according to at least the element, and two cases are included: performing the action based only on the element, and performing the action based on the element and other elements.
Drawings
FIG. 1 is a diagram of a bootstrap circuit for pixel display according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a first data signal and a second data signal according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating a first scan signal and a second scan signal according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating a bootstrap voltage according to an embodiment of the present invention;
FIG. 5 is a diagram of a pixel electrode according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a pixel design with opposite polarities according to an embodiment of the present invention;
FIG. 7 is a diagram of a pixel design with opposite polarities according to an embodiment of the present invention.
Detailed Description
In the following description, numerous technical details are set forth in order to provide a better understanding of the present application. However, it will be understood by those skilled in the art that the technical solutions claimed in the present application may be implemented without these technical details and with various changes and modifications based on the following embodiments.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
A first embodiment of the present application relates to a bootstrap circuit for pixel display, and fig. 1 is a bootstrap circuit diagram for pixel display in an embodiment of the present invention. As shown in fig. 1, the circuit includes: the liquid crystal display device comprises a first transistor, a second transistor, a third transistor, a bootstrap capacitor and a liquid crystal capacitor, wherein the liquid crystal capacitor comprises a pixel electrode and a common electrode;
the drain electrode of the first transistor, one end of the bootstrap capacitor and the pixel electrode of the liquid crystal capacitor are connected to a first reference point, and the drain electrode of the second transistor, the drain electrode of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point;
a first data signal is input to the source electrode of the first transistor, a second data signal is input to the source electrode of the second transistor, and a first scanning signal is input to the grid electrode of the first transistor and the grid electrode of the second transistor;
the gate of the third transistor receives the second scan signal, the source receives the common electrode voltage signal Vcom, and the common electrode of the liquid crystal capacitor is connected to the common electrode voltage signal Vcom.
The circuit working process comprises a first charging stage, a second charging stage and a display stage:
in the first charging stage, the first scanning signal is at a high level, the second scanning signal is at a low level, the first transistor and the second transistor are turned on, the third transistor is turned off, the voltage of a first reference point is 14V of the first data signal, the voltage of a second reference point is 0V of the second data signal, and the voltage at the two ends of the bootstrap capacitor is 14V at the moment;
in the second charging stage, the first scanning signal is at a low level, the second scanning signal is at a high level, the first transistor and the second transistor are turned off, the third transistor is turned on, the second reference point is charged to the common electrode voltage Vcom 7V, and the voltage of the first reference point is 21V through the bootstrap action of the bootstrap capacitor;
in the display stage, the first scanning signal and the second scanning signal are at low level, the first transistor, the second transistor and the third transistor are all turned off, the bootstrap capacitor discharges to the pixel electrode, so that a voltage higher than an input voltage is provided for the pixel electrode, and liquid crystal molecules are deflected by the voltage between the pixel electrode and the common electrode, so that pixel display is realized.
The first Data signal and the second Data signal are shown in fig. 2, where the first Data signal is Data (n), the second Data signal is Data (n +1), and the first Data signal and the second Data signal are timing signals.
In one embodiment, the first Scan signal and the second Scan signal are as shown in fig. 3, where the first Scan signal is Scan (n), the second Scan signal is Scan (n +1), the first Scan signal and the second Scan signal are signals obtained by scanning a pixel frame, and each frame is scanned sequentially by Scan (n) and Scan (n + 1);
in the first charging phase, Date (n) is at
In the second charging stage, when the Scan signal Scan (n +1) is 30V and Scan (n) is-8V, the first transistor and the second transistor are turned off, the third transistor is turned on, and the voltage of the second reference point and Vcom are 7V, so that the voltage of the first reference point becomes 21V due to the bootstrap effect of the bootstrap capacitor. The voltage signal between the point of the first reference point P and the point of the second reference point Q is shown in fig. 5.
And in the display stage, the ITO electrode pixels are charged by the voltage of the first reference point, and liquid crystal molecules are deflected by an electric field formed between the electrode pixels and the common electrode, so that pixel charging is realized.
In one embodiment, the pixel display applying the bootstrap circuit is as shown in fig. 6, and the polarities of two adjacent data lines corresponding to the same column of pixels are opposite at the same time.
In one embodiment, as shown in fig. 7, when a pixel is charged, two adjacent data lines corresponding to a same column of pixels have opposite polarities at a same time, and pixels corresponding to two data lines also have opposite polarities.
In one embodiment, the first transistor, the second transistor and the third transistor are all NMOS.
A second embodiment of the present application relates to a display panel including a plurality of pixel units and a bootstrap circuit for driving the pixel units to perform pixel display.
Preferably, the bootstrap circuit of the display panel includes a first transistor, a second transistor, a third transistor, a bootstrap capacitor, and a liquid crystal capacitor, where the liquid crystal capacitor includes a pixel electrode and a common electrode;
the drain electrode of the first transistor, one end of the bootstrap capacitor and the pixel electrode of the liquid crystal capacitor are connected to a first reference point, and the drain electrode of the second transistor, the drain electrode of the third transistor and the other end of the bootstrap capacitor are connected to a second reference point;
a first data signal is input to the source electrode of the first transistor, a second data signal is input to the source electrode of the second transistor, and a first scanning signal is input to the grid electrode of the first transistor and the grid electrode of the second transistor;
the gate of the third transistor receives the second scan signal, the source receives the common electrode voltage signal Vcom, and the common electrode of the liquid crystal capacitor is connected to the common electrode voltage signal Vcom.
The circuit working process comprises a first charging stage, a second charging stage and a display stage:
in the first charging stage, the first scanning signal is at a high level, the second scanning signal is at a low level, the first transistor and the second transistor are turned on, the third transistor is turned off, the voltage of a first reference point is 14V of the first data signal, the voltage of a second reference point is 0V of the second data signal, and the voltage at the two ends of the bootstrap capacitor is 14V at the moment;
in the second charging stage, the first scanning signal is at a low level, the second scanning signal is at a high level, the first transistor and the second transistor are turned off, the third transistor is turned on, the second reference point is charged to the common electrode voltage Vcom 7V, and the voltage of the first reference point is 21V through the bootstrap action of the bootstrap capacitor;
in the display stage, the first scanning signal and the second scanning signal are at low level, the first transistor, the second transistor and the third transistor are all turned off, the bootstrap capacitor discharges to the pixel electrode, so that a voltage higher than an input voltage is provided for the pixel electrode, and liquid crystal molecules are deflected by the voltage between the pixel electrode and the common electrode, so that pixel display is realized.
The first Data signal and the second Data signal are shown in fig. 2, where the first Data signal is Data (n), the second Data signal is Data (n +1), and the first Data signal and the second Data signal are timing signals.
In one embodiment, the first Scan signal and the second Scan signal are as shown in fig. 3, where the first Scan signal is Scan (n), the second Scan signal is Scan (n +1), the first Scan signal and the second Scan signal are signals obtained by scanning a pixel frame, and the scanning order of each frame is Scan (n) and Scan (n +1) sequentially.
When a certain pixel unit of the display panel needs to display a picture, the bootstrap circuit corresponding to the pixel unit is first in the first charging stage, Date (n) is
Then, the bootstrap circuit corresponding to the pixel unit is in the second charging stage, when the Scan signal Scan (n +1) is 30V and Scan (n) is-8V, the first transistor and the second transistor are turned off, the third transistor is turned on, and the voltage of the second reference point and Vcom are 7V, so that the voltage of the first reference point becomes 21V due to the bootstrap effect of the bootstrap capacitor. The voltage signal between the point of the first reference point P and the point of the second reference point Q is shown in fig. 5.
And finally, the bootstrap circuit corresponding to the pixel unit is in a display stage, the voltage of the first reference point charges the ITO electrode pixel, and liquid crystal molecules are deflected through an electric field formed between the pixel electrode and the common electrode to realize pixel charging.
In one embodiment, a pixel design using the bootstrap circuit is shown in fig. 6 and 7, and two adjacent data lines corresponding to a same column of pixels have opposite polarities at a same time.
It is noted that, in this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the use of the verb "comprise a" to define an element does not exclude the presence of another, same element in a process, method, article, or apparatus that comprises the element. In the present patent application, if it is mentioned that a certain action is executed according to a certain element, it means that the action is executed according to at least the element, and two cases are included: performing the action based only on the element, and performing the action based on the element and other elements.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
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