KR102034047B1 - Liquid crystal display device and method for driving the same - Google Patents
Liquid crystal display device and method for driving the same Download PDFInfo
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- KR102034047B1 KR102034047B1 KR1020120147214A KR20120147214A KR102034047B1 KR 102034047 B1 KR102034047 B1 KR 102034047B1 KR 1020120147214 A KR1020120147214 A KR 1020120147214A KR 20120147214 A KR20120147214 A KR 20120147214A KR 102034047 B1 KR102034047 B1 KR 102034047B1
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- 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
- G09G3/3614—Control of polarity reversal in general
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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
-
- 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
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1343—Electrodes
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/06—Details of flat display driving waveforms
Abstract
The present invention relates to a liquid crystal display device and a driving method thereof that can improve image quality by preventing luminance deviation between an upper end portion and a lower end portion of a liquid crystal panel, and sequentially supplying data voltages to all pixels during each frame period. By temporarily storing the supplied data voltage, and then in the blank period after each frame period, all pixels simultaneously apply the stored data voltage to the pixel electrode, thereby reducing the vertical luminance deviation of the liquid crystal panel according to the AC driving of the common voltage. You can prevent it.
Description
The present invention relates to a liquid crystal display device and a driving method thereof capable of improving image quality by preventing luminance deviation between an upper end portion and a lower end portion of a liquid crystal panel.
Recently, the liquid crystal display (Liquid Crystal Display) is the most used because of the excellent image quality, light weight, thin, low power characteristics of the display elements.
1 is a pixel equivalent circuit diagram of a general liquid crystal display device.
Referring to FIG. 1, a general liquid crystal display device defines a pixel at an intersection of a gate line GL and a data line DL, and each pixel is a thin film transistor (TFT) and a liquid crystal connected to a TFT. A capacitor Clc and a storage capacitor Cst are provided. The liquid crystal capacitor Clc includes a pixel electrode connected to the TFT, and a common electrode for applying an electric field to the liquid crystal together with the pixel electrode. The common voltage is supplied to the common electrode.
The liquid crystal display displays an image by driving the liquid crystal by the pixel voltage charged in the liquid crystal capacitor Clc and the storage capacitor Cst according to the data signal. However, when the pixel voltage always has the same polarity, that is, a positive value or a negative value, the liquid crystal is deteriorated. Accordingly, a data inversion method for changing the polarity of the data signal every frame has been introduced. In order to reduce the driving voltage of the data signal during data inversion, a common voltage AC driving method of changing the polarity of the common voltage Vcom every frame has been introduced.
However, when the polarity of the common voltage Vcom is changed every frame according to the common voltage alternating current driving, the pixel voltage is shifted together and the pixel voltage does not maintain the original voltage value during the shifted pixel voltage. As a result, the voltage between the pixel voltage and the common voltage, that is, the voltage applied to the liquid crystal is lowered, and as shown in FIG. 2, a luminance difference occurs at the upper end and the lower end of the
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a liquid crystal display device and a driving method thereof capable of improving image quality by preventing luminance deviation between an upper end and a lower end of a liquid crystal panel.
In order to achieve the above object, the liquid crystal display according to the exemplary embodiment of the present invention includes a plurality of pixels connected to the first to third gate lines and the data line; Each pixel comprises: a first switching element for supplying a data voltage provided from the data line to the memory electrode in response to a scan signal applied to the first gate line; A first storage capacitor connected to the memory electrode to store the data voltage; A second switching element configured to supply a common voltage applied to the common electrode from the common line to the pixel electrode in response to a reset signal applied to the second gate line; A third switching element configured to supply the data voltage stored in the first storage capacitor to the pixel electrode in response to a write signal applied to a third gate line; A second storage capacitor connected to the pixel electrode to store the data voltage; In each frame period, as the scan signal is sequentially applied to the first gate lines, the data voltage is stored in the first storage capacitor for each pixel, and in the blank period after each frame period, the reset The common voltage is supplied to the pixel electrode for each pixel as a signal is simultaneously applied to the second gate lines, and the first storage for each pixel as the write signal is simultaneously applied to the third gate lines. After the data voltage stored in the capacitor is supplied to the pixel electrode, the polarity of the common voltage is inverted.
The common electrode may form a horizontal electric field or a vertical electric field together with the pixel electrode.
A memory electrode connected to the first switching element and overlapping a next common line with a first insulating layer interposed therebetween; And a common electrode connected to the next common line through a contact hole and overlapping the memory electrode with a second insulating layer interposed therebetween.
The polarity of the common voltage is opposite to the polarity of the data voltage.
In addition, in order to achieve the above object, the driving method of the liquid crystal display according to the embodiment of the present invention comprises a plurality of pixels connected to the first to third gate line and the data line; Each pixel comprises: a first switching element for supplying a data voltage provided from the data line to the memory electrode in response to a scan signal applied to the first gate line; A first storage capacitor connected to the memory electrode to store the data voltage; A second switching element configured to supply a common voltage applied to the common electrode from the common line to the pixel electrode in response to a reset signal applied to the second gate line; A third switching element configured to supply the data voltage stored in the first storage capacitor to the pixel electrode in response to a write signal applied to a third gate line; And a second storage capacitor connected to the pixel electrode to store the data voltage, wherein the scan signal is sequentially applied to the first gate lines in each frame period. Applying and storing the data voltage in the first storage capacitor for each pixel; In the blank period after each frame period, the reset signal is simultaneously applied to the second gate lines to supply the common voltage to the pixel electrode for each pixel, and then the write signal is applied to the third gate lines. And simultaneously applying the data voltage stored in the first storage capacitor to the pixel electrode for each pixel, and then inverting the polarity of the common voltage.
Inverting the polarity of the common voltage may be such that the polarity of the common voltage is opposite to the polarity of the data voltage.
The present invention sequentially supplies data voltages to all pixels during each frame period, and allows each pixel to temporarily store the supplied data voltages, and then, in the blank period after each frame period, all pixels simultaneously store the data voltages. By applying to the pixel electrode, it is possible to prevent the vertical brightness deviation of the liquid crystal panel due to the AC drive of the common voltage.
1 is a pixel equivalent circuit diagram of a general liquid crystal display device.
FIG. 2 is a diagram illustrating a problem in luminance variation of upper and lower ends of a liquid crystal panel according to common voltage AC driving.
3 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention. 4 is a driving waveform diagram of the
5 is an equivalent circuit diagram illustrating a pixel structure of the present invention.
FIG. 6 is a plan view schematically illustrating the pixel illustrated in FIG. 5.
FIG. 7 is a cross-sectional view taken along line AA ′ of FIG. 6.
Hereinafter, a liquid crystal display and a driving method thereof according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.
3 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention. 4 is a driving waveform diagram of the
The liquid crystal display shown in FIG. 3 includes a
The present invention sequentially supplies data voltages to all pixels during each frame period, and allows each pixel to temporarily store the supplied data voltages, and then, in the blank period after each frame period, all pixels simultaneously store the data voltages. By applying to the pixel electrode, it is possible to prevent the vertical luminance deviation of the
The
A color filter array is formed on the upper substrate of the
The
The
The common voltage supply unit 8 generates a common voltage Vcom and supplies it to the common line CL of the
The
Hereinafter, the structure of each pixel according to the present invention will be described in detail.
5 is an equivalent circuit diagram illustrating a pixel structure of the present invention. FIG. 6 is a plan view schematically illustrating the pixel illustrated in FIG. 5. FIG. 7 is a cross-sectional view taken along the line AA ′ of FIG. 6.
5 and 6, each pixel of the present invention includes first to third TFTs T1 to T3, first and second storage capacitors Cst2, and a liquid crystal capacitor Clc.
The first TFT T1 supplies a data voltage provided from the data line DL to the memory electrode 26 (FIG. 6) in response to a scan signal Scan applied to the first gate line GL1. To this end, as shown in FIG. 7, the first TFT T1 includes a
The first storage capacitor Cst1 is connected to the
The second TFT T2 receives the common voltage Vcom applied from the common line CL to the
The third TFT T3 supplies the data voltage stored in the first storage capacitor Cst1 to the
The second storage capacitor Cst2 is connected to the
The liquid crystal capacitor Clc is formed of the
Hereinafter, the driving method of each pixel according to the present invention will be described in detail with reference to FIGS. 4 and 5.
First, in each frame period, the
Subsequently, in the blank period after each frame period, the
Subsequently, in the blank period after each frame period, the
Then, in the blank period after each frame period, the common voltage supply unit 8 inverts the polarity of the first and second common voltages Vcom after the write signal Write is output from the
As described above, the present invention sequentially supplies data voltages to all the pixels during each frame period, and allows each pixel to temporarily store the supplied data voltages, and then, in the blank period after each frame period, all the pixels By simultaneously applying the stored data voltage to the pixel electrode, it is possible to prevent the vertical brightness deviation of the liquid crystal panel caused by the AC drive of the common voltage.
The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.
2: liquid crystal panel 4: gate driver
6: data driver 8: common voltage supply
10: timing controller 16: protrusion of common line
26: memory electrode 34: common electrode
38: pixel electrode 36: contact hole
Claims (7)
Each pixel is
A first switching element for supplying a data voltage provided from the data line to the memory electrode in response to a scan signal applied to the first gate line;
A first storage capacitor connected to the memory electrode to store the data voltage;
A second switching element configured to supply a common voltage applied to the common electrode from the common line to the pixel electrode in response to a reset signal applied to the second gate line;
A third switching element configured to supply the data voltage stored in the first storage capacitor to the pixel electrode in response to a write signal applied to a third gate line;
A second storage capacitor connected to the pixel electrode to store the data voltage;
In each frame period, as the scan signal is sequentially applied to the first gate lines, the data voltage is stored in the first storage capacitor for each pixel.
In the blank period after each frame period, as the reset signal is simultaneously applied to the second gate lines, the common voltage is supplied to the pixel electrode of each pixel to convert the voltage of each pixel electrode to the common voltage. And the data voltage stored in the first storage capacitor for each pixel is supplied to the pixel electrode of each pixel as the write signal is simultaneously applied to the third gate lines, and then the polarity of the common voltage is inverted. Liquid crystal display device characterized in that.
The common electrode forms a horizontal electric field together with the pixel electrode.
The first storage capacitor
A memory electrode connected to the first switching element and overlapping the next common line with a first insulating layer interposed therebetween;
And a common electrode connected to the next common line through a contact hole and overlapping the memory electrode with a second insulating layer interposed therebetween.
The common electrode forms a vertical electric field together with the pixel electrode.
The polarity of the common voltage is opposite to the polarity of the data voltage.
Sequentially applying the scan signal to the first gate lines in each frame period, and storing the data voltage in the first storage capacitor for each pixel;
In the blank period after each frame period, the reset signal is simultaneously applied to the second gate lines to supply the common voltage to the pixel electrode of each pixel to initialize the voltage of each pixel electrode to the common voltage. And simultaneously applying the write signal to the third gate lines to supply the data voltage stored in the first storage capacitor for each pixel to the pixel electrode of each pixel, and then reverse the polarity of the common voltage. Method of driving a liquid crystal display device comprising a.
Inverting the polarity of the common voltage is such that the polarity of the common voltage is opposite to the polarity of the data voltage.
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KR1020120147214A KR102034047B1 (en) | 2012-12-17 | 2012-12-17 | Liquid crystal display device and method for driving the same |
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KR1020120147214A KR102034047B1 (en) | 2012-12-17 | 2012-12-17 | Liquid crystal display device and method for driving the same |
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CN107068107A (en) * | 2017-06-23 | 2017-08-18 | 京东方科技集团股份有限公司 | Image element circuit, display device and driving method |
US10699653B2 (en) * | 2018-08-31 | 2020-06-30 | Au Optronics Corporation | Display panel and pixel circuit |
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JP2003222902A (en) * | 2002-01-30 | 2003-08-08 | Hitachi Ltd | Display and module |
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KR20080037756A (en) * | 2006-10-27 | 2008-05-02 | 엘지디스플레이 주식회사 | Liquid crystal display panel, a in-plain switching liquid crystal display device and method for driving the same |
KR101429922B1 (en) * | 2009-12-02 | 2014-08-14 | 엘지디스플레이 주식회사 | Driving circuit for liquid crystal display device and method for driving the same |
KR101407308B1 (en) * | 2010-12-14 | 2014-06-13 | 엘지디스플레이 주식회사 | Driving circuit for liquid crystal display device and method for driving the same |
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