WO2016141615A1 - 一种vcom生成电路及液晶显示器 - Google Patents

一种vcom生成电路及液晶显示器 Download PDF

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WO2016141615A1
WO2016141615A1 PCT/CN2015/075921 CN2015075921W WO2016141615A1 WO 2016141615 A1 WO2016141615 A1 WO 2016141615A1 CN 2015075921 W CN2015075921 W CN 2015075921W WO 2016141615 A1 WO2016141615 A1 WO 2016141615A1
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Prior art keywords
liquid crystal
circuit
vcom
crystal display
output
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English (en)
French (fr)
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房兆林
郭东胜
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TCL China Star Optoelectronics Technology Co Ltd
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Shenzhen China Star Optoelectronics Technology Co Ltd
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Priority to US14/901,038 priority Critical patent/US9696570B2/en
Publication of WO2016141615A1 publication Critical patent/WO2016141615A1/zh
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
    • G05F3/02—Regulating voltage or current
    • G05F3/08—Regulating voltage or current wherein the variable is DC
    • G05F3/10—Regulating voltage or current wherein the variable is DC using uncontrolled devices with non-linear characteristics
    • G05F3/16—Regulating voltage or current wherein the variable is DC using uncontrolled devices with non-linear characteristics being semiconductor devices
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3648—Control of matrices with row and column drivers using an active matrix
    • G09G3/3655—Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/136—Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • G02F1/1362—Active matrix addressed cells
    • G02F1/1368—Active matrix addressed cells in which the switching element is a three-electrode device

Definitions

  • the present invention relates to the field of display technologies, and in particular, to a VCOM generation circuit and a liquid crystal display.
  • TFT Thin Film Transistor
  • Each pixel in the TFT liquid crystal display includes at least one TFT and a layer of liquid crystal material, and the deflection of the liquid crystal molecules is controlled by the on and off of the TFT, thereby changing the transmittance of the liquid crystal molecules.
  • each pixel two ends of the liquid crystal material layer are respectively connected to one end of the TFT and the liquid crystal driving reference voltage VCOM input end.
  • the potential between the one end of the TFT and the VCOM input end is inconsistent.
  • the liquid crystal layer may be slightly transparent or transparent, the corresponding pixel may have a certain brightness or be completely illuminated; conversely, when the potentials of both ends of the liquid crystal layer are uniform, the liquid crystal layer is opaque, and the corresponding pixel is not displayed.
  • the turn-on or turn-off of the TFT is controlled by the gate voltage VG of the TFT.
  • the gate voltage VG is generally generated by the charge and discharge of the VAA voltage at the power input terminal, and VCOM is generally obtained by voltage division of the VAA voltage.
  • the embodiment of the invention provides a VCOM generation circuit and a liquid crystal display, which can solve the problem that the liquid crystal display appears in a slightly bright state on the machine screen.
  • a first aspect of the embodiments of the present invention provides a VCOM generating circuit, which may include:
  • a voltage dividing circuit connected between the power input end of the VCOM generating circuit and the ground, the voltage dividing circuit comprising a voltage output end;
  • An op amp output circuit an input end of the op amp output circuit is connected to a voltage output end of the voltage dividing circuit, and an output end of the op amp output circuit is a VCOM input end of the liquid crystal display, and is used in the liquid crystal display Outputting a liquid crystal driving reference voltage VCOM during operation to charge the liquid crystal layer in the liquid crystal display;
  • a delay circuit coupled between the input of the op amp output circuit and the ground for delaying the rate of change of the VCOM when the VCOM output of the op amp output circuit changes.
  • the VCOM generating circuit further includes a discharging circuit, wherein:
  • the discharge circuit is coupled between an output of the op amp output circuit and ground for providing a discharge path for the liquid crystal layer when the liquid crystal display is turned off.
  • the op amp output circuit includes an operational amplifier OP and a first capacitor C1, and the delay circuit includes a second capacitor C2, wherein:
  • An inverting input terminal of the operational amplifier OP is connected to a voltage output end of the voltage dividing circuit, an inverting input end of the operational amplifier OP is connected to an output end of the operational amplifier OP, and an output end of the operational amplifier OP passes through The first capacitor C1 is grounded;
  • One end of the second capacitor C2 is connected to the non-inverting input terminal of the operational amplifier OP, and the other end is grounded.
  • the discharge circuit includes a first resistor R1, and one end of the first resistor R1 is connected to an output end of the op amp output circuit, and the other end is grounded.
  • the voltage dividing circuit comprises a second resistor R2, a third resistor R3 and an adjustable resistor Rv, wherein:
  • the power input end of the VCOM generating circuit is grounded through the second resistor R2, the adjustable resistor Rv and the third resistor R3 connected in series;
  • the adjustable resistor Rv leads to a voltage output terminal of the voltage dividing circuit.
  • a second aspect of the present invention provides a liquid crystal display, comprising: a VCOM generating circuit, a backlight, and a liquid crystal display according to any one of the first aspects of the present invention, wherein the liquid crystal display
  • the VCOM generating circuit is connected, and the backlight is disposed behind the liquid crystal display.
  • the backlight comprises an LED array of LEDs and a light guide, wherein:
  • the light guide plate is located between the LED array and the liquid crystal display; or the light guide plate and the LED array are arranged behind the liquid crystal display, and the LED array is arranged on a side of the light guide plate. .
  • the delay circuit can delay the change speed of the VCOM.
  • the rise of the VCOM lags behind the rise of the VAA, and is close to or synchronized with the rise of the TFT gate voltage VG of the control liquid crystal switch, avoiding the TFT.
  • the liquid crystal layer is opaque before the liquid crystal display starts to work, thereby solving the problem that the display will appear slightly bright state before starting the power in the prior art.
  • FIG. 1 is a schematic structural diagram of an embodiment of a VCOM generating circuit according to an embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of another embodiment of a VCOM generating circuit according to an embodiment of the present invention.
  • FIG. 3 is a circuit diagram of an embodiment of a VCOM generation circuit according to an embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of an embodiment of a liquid crystal display according to an embodiment of the present invention.
  • the embodiment of the invention provides a VCOM generating circuit and a liquid crystal display, which can prevent the liquid crystal display from being slightly brightened before being turned on.
  • FIG. 1 is a schematic structural diagram of an embodiment of a VCOM generating circuit according to an embodiment of the present invention.
  • the VCOM generating circuit may include a voltage dividing circuit U1, an operational amplifier output circuit U2, and a delay circuit U3, wherein:
  • the voltage dividing circuit U1 is connected between the power input end of the VCOM generating circuit and the ground GND, the voltage dividing circuit U1 includes a voltage output terminal; and an input terminal VCOM-in of the operational amplifier output circuit U2 is connected.
  • a voltage output end of the voltage dividing circuit U1, an output terminal VCOM-out of the operational amplifier output circuit U2 is a VCOM input end of the liquid crystal display, and is configured to output a liquid crystal driving reference voltage VCOM when the liquid crystal display operates, to the liquid crystal The liquid crystal layer in the display is charged;
  • the delay circuit U3 is connected between the input terminal VCOM-in of the operational amplifier output circuit U2 and the ground GND, and is used for the liquid crystal driving reference voltage VCOM outputted by the operational amplifier output circuit U2.
  • the change speed of the VCOM is delayed when changing.
  • one end of the liquid crystal layer in the liquid crystal display is connected to the output terminal VCOM-out of the operational output circuit U2, and the other end of the liquid crystal layer is connected to the drain of the TFT device.
  • VCOM is obtained by dividing the voltage VAA input from the power input terminal, the rise of VCOM is synchronized with the rise of VAA, and the rise of VG is lagging behind the rise of VAA, and the liquid crystal layer is connected to the TFT before the VG rises to VGH.
  • the liquid crystal layer can be slightly transparent, and the ambient light passes through the liquid crystal layer to make the liquid crystal display. Presents a slightly bright state.
  • the delay circuit U3 is added to the VCOM generation circuit of the embodiment of the present invention, which can delay the change speed of the VCOM.
  • the rise of the VCOM also lags behind the rise of the VAA, and is close to or synchronized with the rise of the VG to avoid the TFT.
  • there is a voltage at both ends of the liquid crystal layer so that the liquid crystal layer is opaque before the liquid crystal display starts to work, thereby solving the problem that the display will appear slightly bright state before starting the power in the prior art.
  • FIG. 2 is a schematic structural diagram of another embodiment of a VCOM generating circuit according to an embodiment of the present invention.
  • the VCOM generating circuit may further include a discharging circuit. U4, wherein the discharge circuit U4 is connected between the output terminal VCOM-out of the operational amplifier output circuit U2 and the ground GND for providing a discharge path for the liquid crystal layer when the liquid crystal display is turned off.
  • the liquid crystal material has a capacitive characteristic, and the liquid crystal display charges the liquid crystal layer when the liquid crystal display is in operation. When the liquid crystal display is turned off, the liquid crystal layer is slowly discharged, and when the liquid crystal layer is discharged, the liquid crystal display is turned off successfully.
  • the discharge circuit U4 can provide a discharge path for the liquid crystal layer, so that the accumulated charge of the liquid crystal layer can be quickly released, speeding up the falling speed of the VCOM, and enabling the liquid crystal display to be quickly turned off.
  • the operational amplifier output circuit U2 includes an operational amplifier OP and a first capacitor C1, and the delay circuit includes a second capacitor C2, wherein:
  • the non-inverting input terminal of the operational amplifier OP is connected to the voltage output terminal of the voltage dividing circuit U1, and the inverting input terminal of the operational amplifier OP is connected to the output terminal VCOM-out of the operational amplifier OP, the operational amplifier OP
  • the output terminal VCOM-out is grounded through the first capacitor C1; one end of the second capacitor C2 is connected to the non-inverting input terminal of the operational amplifier OP, and the other end is grounded.
  • the discharge circuit U4 includes a first resistor R1, and one end of the first resistor R1 is connected to the output terminal VCOM-out of the operational amplifier output circuit U2, and the other end is grounded.
  • the voltage dividing circuit U1 includes a second resistor R2, a third resistor R3, and an adjustable resistor Rv, wherein:
  • the power input end of the VCOM generating circuit is sequentially grounded through the second resistor R2, the adjustable resistor Rv and the third resistor R3 connected in series; the adjustable resistor Rv leads out the voltage output of the voltage dividing circuit end.
  • the voltage VAA input from the power input terminal is divided by the second resistor R2, the adjustable resistor Rv and the third resistor R3, and the voltage output terminal of the voltage dividing circuit is drawn in the adjustable resistor Rv, and the voltage of the voltage output terminal Input to the non-inverting input of the operational amplifier OP, amplified by the operational amplifier OP.
  • the non-inverting input terminal of the operational amplifier OP is grounded through the second capacitor C2. Since the voltage across the second capacitor C2 cannot be abruptly changed, when the liquid crystal display is turned on and the VAA suddenly increases, the input voltage of the operational amplifier OP does not follow the VAA.
  • the electric charge accumulated on the liquid crystal layer can be quickly introduced into the ground through the first resistor R1, which shortens the discharge time of the liquid crystal layer after shutdown, and prevents the liquid crystal layer from having a certain light transmittance after the shutdown, so that the liquid crystal display is in a slightly bright state.
  • an embodiment of the present invention further provides a liquid crystal display.
  • FIG. 4 is a schematic structural diagram of an embodiment of a liquid crystal display according to an embodiment of the present invention.
  • the liquid crystal display may include the VCOM generating circuit in the embodiment as described in any one of FIGS. 1-3, and may further include a backlight and a liquid crystal display, wherein the liquid crystal display and the VCOM A circuit connection is generated, the backlight being placed behind the liquid crystal display.
  • the liquid crystal display panel may be composed of a combination of a front and rear substrate, a plurality of TFT devices, electrodes, a liquid crystal material layer, a color filter, a polarizing plate, and the like.
  • the liquid crystal display may further include a driving circuit, and the VCOM generating circuit may be independent of the driving circuit or a part of the driving circuit.
  • the backlight may include an LED array and a light guide plate, wherein optionally, the light guide plate may be located between the LED array and the liquid crystal display, and the backlight is a direct backlight. Or, the light guide plate and the LED array are arranged behind the liquid crystal display, and the LED array is arranged on a side of the light guide plate, and the backlight is a side-entry backlight.

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Abstract

一种VCOM生成电路及液晶显示器，其中VCOM生成电路包括：分压电路（U1），连接在VCOM生成电路的电源输入端和地（GND）之间，包括一个电压输出端；运放输出电路（U2），其一个输入端（VCOM-in）连接分压电路（U1）的电压输出端，输出端（VCOM-out）为液晶显示器的VCOM输入端，用于在液晶显示器工作时输出液晶驱动参考电压VCOM，以给液晶显示器中的液晶层充电；延迟电路（U3），连接在运放输出电路（U2）的一个输入端（VCOM-in）和地（GND）之间，用于在运放输出电路（U2）输出的VCOM变化时延缓VCOM的变化速度。通过延迟电路（U3）延缓液晶显示器开启时VCOM的上升速度，使其与控制液晶开关的TFT栅极电压VG的上升速度接近，从而解决液晶显示器开机前会出现微亮状态的问题。

Description

一种VCOM生成电路及液晶显示器
本发明要求2015年3月10日递交的发明名称为“一种VCOM生成电路及液晶显示器”的申请号为201510104439.3的在先申请的优先权，上述在先申请的内容以引入的方式并入本文本中。
技术领域
本发明涉及显示技术领域，尤其涉及一种VCOM生成电路及液晶显示器。
背景技术
目前市场上常见的一种显示器是薄膜晶体管(Thin Film Transistor，TFT)液晶显示器。TFT液晶显示器中每个像素点包括至少一个TFT和一层液晶材料，通过TFT的导通和关断控制液晶分子的偏转，从而改变液晶分子的透光度。
在每个像素中，液晶材料层的两端分别连接TFT的一端和液晶驱动参考电压VCOM输入端，当液晶层的两端存在电压时，即上述TFT的一端与VCOM输入端之间的电位不一致时，液晶层可能微透光或透光，对应像素会有一定的亮度或完全点亮；反之，当液晶层的两端电位一致时，液晶层不透光，对应像素不显示。其中，TFT的导通或关断受控于TFT的栅极电压VG，栅极电压VG一般由电源输入端的VAA电压经过电荷泵充放电产生，而VCOM则一般由VAA电压分压得到。
现有技术中，当液晶显示器开机时，由于电荷泵的滞后性，VG的上升滞后于VCOM，在VCOM已经上升稳定后，VG还暂时处于低电位，液晶层由于两端存在电压而微透光。由于背光源点亮得较迟，在显示器开机成功之前，环境光由于液晶层的微透而使显示器呈现一种微亮状态。这种微亮状态容易使用户误以为显示器出现了质量问题或发生了故障，不仅影响用户体验，甚至还会影响显示器产品的销量。
发明内容
本发明实施例提供一种VCOM生成电路及液晶显示器，可解决液晶显示器在开机器屏幕出现微亮状态的问题。
本发明实施例第一方面提供一种VCOM生成电路，可包括：
分压电路，所述分压电路连接在所述VCOM生成电路的电源输入端和地之间，所述分压电路包括一个电压输出端；
运放输出电路，所述运放输出电路的一个输入端连接所述分压电路的电压输出端，所述运放输出电路的输出端为液晶显示器的VCOM输入端，用于在所述液晶显示器工作时输出液晶驱动参考电压VCOM，以给所述液晶显示器中的液晶层充电；
延迟电路，所述延迟电路连接在所述运放输出电路的实施一个输入端和地之间，用于在所述运放输出电路输出的所述VCOM变化时延缓所述VCOM的变化速度。
可选地，所述VCOM生成电路还包括放电电路，其中：
所述放电电路连接在所述运放输出电路的输出端和地之间，用于在所述液晶显示器关闭时为所述液晶层提供放电路径。
可选地，所述运放输出电路包括运算放大器OP和第一电容C1，所述延迟电路包括第二电容C2，其中：
所述运算放大器OP的同相输入端连接所述分压电路的电压输出端，所述运算放大器OP的反相输入端连接所述运算放大器OP的输出端，所述运算放大器OP的输出端通过所述第一电容C1接地；
所述第二电容C2一端连接所述运算放大器OP的同相输入端，另一端接地。
可选地，所述放电电路包括第一电阻R1，所述第一电阻R1一端连接所述运放输出电路的输出端，另一端接地。
可选地，所述分压电路包括第二电阻R2、第三电阻R3和可调电阻Rv，其中：
所述VCOM生成电路的电源输入端依次通过串联的所述第二电阻R2、所述可调电阻Rv和所述第三电阻R3接地；
所述可调电阻Rv引出所述分压电路的电压输出端。
本发明实施例第二方面提供一种液晶显示器，所述液晶显示器包括如本发明实施例第一方面任一项所述的VCOM生成电路、背光源和液晶显示屏，其中所述液晶显示屏与所述VCOM生成电路连接，所述背光源置于所述液晶显示屏的后方。
可选地，所述背光源包括发光二极管LED阵列和导光板，其中：
所述导光板位于所述LED阵列和所述液晶显示屏中间；或者，所述导光板与所述LED阵列并排位于所述液晶显示屏后方且所述LED阵列排列于所述导光板的侧边。
本发明实施例中，延迟电路可延缓VCOM的变化速度，当液晶显示器开机时，VCOM的上升滞后于VAA的上升，而与控制液晶开关的TFT栅极电压VG的上升接近或同步，避免在TFT导通之前液晶层的两端存在电压，使液晶层在液晶显示器开始工作之前不透光，从而解决了现有技术中开机前显示器会出现微亮状态的问题。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1是本发明实施例提供的VCOM生成电路的一实施例的结构示意图；
图2是本发明实施例提供的VCOM生成电路的另一实施例的结构示意图；
图3是本发明实施例提供的VCOM生成电路的一实施例的电路图；
图4是本发明实施例提供的液晶显示器的一实施例的结构示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明实施例提供一种VCOM生成电路及液晶显示器，可避免液晶显示器在开机前产生微亮状态，下面将结合附图对本发明的实施例进行详细说明。
参见图1，为本发明实施例提供的VCOM生成电路的一实施例的结构示意图。如图1所示，VCOM生成电路可包括分压电路U1、运放输出电路U2和延迟电路U3，其中：
所述分压电路U1连接在所述VCOM生成电路的电源输入端和地GND之间，所述分压电路U1包括一个电压输出端；所述运放输出电路U2的一个输入端VCOM-in连接所述分压电路U1的电压输出端，运放输出电路U2的输出端VCOM-out为液晶显示器的VCOM输入端，用于在所述液晶显示器工作时输出液晶驱动参考电压VCOM，给所述液晶显示器中的液晶层充电；所述延迟电路U3连接在所述运放输出电路U2的输入端VCOM-in和地GND之间，用于在所述运放输出电路U2输出的液晶驱动参考电压VCOM变化时延缓所述VCOM的变化速度。
具体实施中，液晶显示器中液晶层的一端连接运放输出电路U2的输出端VCOM-out，液晶层的另一端连接TFT器件的漏极。启动液晶显示器时，VCOM上升到一稳定值，TFT器件的栅极电压VG逐渐上升，当栅极电压VG上升到TFT的开启电压VGH时，TFT导通，液晶显示器开机完成，开始工作。现有技术中，VCOM由电源输入端输入的电压VAA分压得到，VCOM的上升与VAA的上升同步，而VG的上升则滞后于VAA的上升，在VG上升到VGH之前，液晶层与TFT连接的一端还没有数据写入，处于低电位，而液晶层另一端的电位已上升到稳定后的VCOM，由于两端存在电位差，液晶层可以稍微透光，环境光透过液晶层使液晶显示器呈现一种微亮状态。
本发明实施例的VCOM生成电路中增加了延迟电路U3，可延缓VCOM的变化速度，当液晶显示器开机时，VCOM的上升也滞后于VAA的上升，而与VG的上升接近或同步，避免在TFT导通之前液晶层的两端存在电压，使液晶层在液晶显示器开始工作之前不透光，从而解决了现有技术中开机前显示器会出现微亮状态的问题。
参见图2，为本发明实施例提供的VCOM生成电路的另一实施例的结构示意图。如图2所示，在图1的基础上，VCOM生成电路还可包括放电电路 U4，其中所述放电电路U4连接在所述运放输出电路U2的输出端VCOM-out和地GND之间，用于在所述液晶显示器关闭时为所述液晶层提供放电路径。具体地，液晶材料具有容性特质，液晶显示器工作时会为液晶层充电，当关闭液晶显示器时，液晶层慢慢放电，当液晶层放电完毕时，液晶显示器才关机成功。在液晶层放电期间，液晶层仍然具有一定的透光性，使关机过程中显示器会出现微亮状态。而放电电路U4可以为液晶层提供一条放电路径，使液晶层积累的电荷可以迅速释放，加快VCOM的下降速度，使液晶显示器能快速关闭。
请一并参阅图3，如图3所示，所述运放输出电路U2包括运算放大器OP和第一电容C1，所述延迟电路包括第二电容C2，其中：
所述运算放大器OP的同相输入端连接所述分压电路U1的电压输出端，所述运算放大器OP的反相输入端连接所述运算放大器OP的输出端VCOM-out，所述运算放大器OP的输出端VCOM-out通过所述第一电容C1接地；所述第二电容C2一端连接所述运算放大器OP的同相输入端，另一端接地。
所述放电电路U4包括第一电阻R1，所述第一电阻R1一端连接所述运放输出电路U2的输出端VCOM-out，另一端接地。
所述分压电路U1包括第二电阻R2、第三电阻R3和可调电阻Rv，其中：
所述VCOM生成电路的电源输入端依次通过串联的所述第二电阻R2、所述可调电阻Rv和所述第三电阻R3接地；所述可调电阻Rv引出所述分压电路的电压输出端。
具体实现中，从电源输入端输入的电压VAA被第二电阻R2、可调电阻Rv和第三电阻R3分压，在可调电阻Rv中引出分压电路的电压输出端，该电压输出端的电压输入到运算放大器OP的同相输入端，由运算放大器OP放大输出。运算放大器OP的同相输入端通过第二电容C2接地，由于第二电容C2两端电压不能突变的特性，当开启液晶显示器，VAA突然增大时，运算放大器OP的输入电压不会随着VAA的增大而突变，而是滞后于VAA的变化逐渐增大，使得运算放大器OP的输出电压VCOM也逐渐增大，从而可延缓VCOM的变化，使VCOM的变化速度与VG的变化速度趋于一致。当VG上升到VGH 时，VCOM也上升到一个稳定值，液晶显示器开始正常工作，此时VGH和VCOM对液晶层充电。当关闭液晶显示器时，液晶层开始放电，第一电阻R1的一端与液晶层的一端相连，第一电阻R1的另一端接地，为液晶层提供了一条放电路径。液晶层上积累的电荷可通过第一电阻R1迅速导入地，缩短了关机后液晶层的放电时间，避免关机后液晶层还具有一定透光性而使液晶显示器处于微亮状态。
相应地，本发明实施例还提供了一种液晶显示器。
参见图4，为本发明实施例提供的液晶显示器的一实施例的结构示意图。如图4所示，该液晶显示器可包括如图1-3任一项所描述的实施例中的VCOM生成电路，还可包括背光源和液晶显示屏，其中所述液晶显示屏与所述VCOM生成电路连接，所述背光源置于所述液晶显示屏的后方。
具体地，该液晶显示屏可以由前后基板、多个TFT器件、电极、液晶材料层、彩色滤光片、偏光板等多层材料组合而成。具体实施中，该液晶显示器还可包括驱动电路，上述VCOM生成电路可以独立于驱动电路，也可作为驱动电路的一部分。
作为一种可行的实施方式，背光源可包括发光二极管LED阵列和导光板，其中可选地，导光板可以位于所述LED阵列和所述液晶显示屏中间，此时背光源为直下式背光源；或者，导光板与所述LED阵列并排位于所述液晶显示屏后方且所述LED阵列排列于所述导光板的侧边，此时背光源为侧入式背光源。
以上所述的实施方式，并不构成对该技术方案保护范围的限定。任何在上述实施方式的精神和原则之内所作的修改、等同替换和改进等，均应包含在该技术方案的保护范围之内。

Claims (11)

  1. 一种液晶驱动参考电压VCOM生成电路，其特征在于，包括：
    分压电路，所述分压电路连接在所述VCOM生成电路的电源输入端和地之间，所述分压电路包括一个电压输出端；
    运放输出电路，所述运放输出电路的一个输入端连接所述分压电路的电压输出端，所述运放输出电路的输出端为液晶显示器的VCOM输入端，用于在所述液晶显示器工作时输出液晶驱动参考电压VCOM，以给所述液晶显示器中的液晶层充电；
    延迟电路，所述延迟电路连接在所述运放输出电路的所述一个输入端和地之间，用于在所述运放输出电路输出的所述VCOM变化时延缓所述VCOM的变化速度。
  2. 根据权利要求1所述的VCOM生成电路，其特征在于，所述VCOM生成电路还包括放电电路，其中：
    所述放电电路连接在所述运放输出电路的输出端和地之间，用于在所述液晶显示器关闭时为所述液晶层提供放电路径。
  3. 根据权利要求2所述的VCOM生成电路，其特征在于，所述运放输出电路包括运算放大器OP和第一电容C1，所述延迟电路包括第二电容C2，其中：
    所述运算放大器OP的同相输入端连接所述分压电路的电压输出端，所述运算放大器OP的反相输入端连接所述运算放大器OP的输出端，所述运算放大器OP的输出端通过所述第一电容C1接地；
    所述第二电容C2一端连接所述运算放大器OP的同相输入端，另一端接地。
  4. 根据权利要求2所述的VCOM生成电路，其特征在于，所述放电电路包括第一电阻R1，所述第一电阻R1一端连接所述运放输出电路的输出端，另 一端接地。
  5. 根据权利要求1所述的VCOM生成电路，其特征在于，所述分压电路包括第二电阻R2、第三电阻R3和可调电阻Rv，其中：
    所述VCOM生成电路的电源输入端依次通过串联的所述第二电阻R2、所述可调电阻Rv和所述第三电阻R3接地；
    所述可调电阻Rv引出所述分压电路的电压输出端。
  6. 一种液晶显示器，其特征在于，所述液晶显示器包括VCOM生成电路、背光源和液晶显示屏，其中所述液晶显示屏与所述VCOM生成电路连接，所述背光源置于所述液晶显示屏的后方；
    所述VCOM生成电路包括：
    分压电路，所述分压电路连接在所述VCOM生成电路的电源输入端和地之间，所述分压电路包括一个电压输出端；
    运放输出电路，所述运放输出电路的一个输入端连接所述分压电路的电压输出端，所述运放输出电路的输出端为液晶显示器的VCOM输入端，用于在所述液晶显示器工作时输出液晶驱动参考电压VCOM，以给所述液晶显示器中的液晶层充电；
    延迟电路，所述延迟电路连接在所述运放输出电路的所述一个输入端和地之间，用于在所述运放输出电路输出的所述VCOM变化时延缓所述VCOM的变化速度。
  7. 根据权利要求6所述的液晶显示器，其特征在于，所述背光源包括发光二极管LED阵列和导光板，其中：
    所述导光板位于所述LED阵列和所述液晶显示屏中间；或者，所述导光板与所述LED阵列并排位于所述液晶显示屏后方且所述LED阵列排列于所述导光板的侧边。
  8. 根据权利要求6所述的液晶显示器，其特征在于，所述VCOM生成电 路还包括放电电路，其中：
    所述放电电路连接在所述运放输出电路的输出端和地之间，用于在所述液晶显示器关闭时为所述液晶层提供放电路径。
  9. 根据权利要求8所述的液晶显示器，其特征在于，所述运放输出电路包括运算放大器OP和第一电容C1，所述延迟电路包括第二电容C2，其中：
    所述运算放大器OP的同相输入端连接所述分压电路的电压输出端，所述运算放大器OP的反相输入端连接所述运算放大器OP的输出端，所述运算放大器OP的输出端通过所述第一电容C1接地；
    所述第二电容C2一端连接所述运算放大器OP的同相输入端，另一端接地。
  10. 根据权利要求8所述的液晶显示器，其特征在于，所述放电电路包括第一电阻R1，所述第一电阻R1一端连接所述运放输出电路的输出端，另一端接地。
  11. 根据权利要求6所述的液晶显示器，其特征在于，所述分压电路包括第二电阻R2、第三电阻R3和可调电阻Rv，其中：
    所述VCOM生成电路的电源输入端依次通过串联的所述第二电阻R2、所述可调电阻Rv和所述第三电阻R3接地；
    所述可调电阻Rv引出所述分压电路的电压输出端。
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