KR20090005862A - Driving Method of Liquid Crystal Display Panel - Google Patents

Abstract

According to an aspect of the present invention, there is provided a method of driving a liquid crystal display panel including a pixel electrode, a main data line and a dummy data line superimposed thereon, the method including applying a normal data signal to the main data line and applying the normal data signal to the main data line. A method of driving a liquid crystal display panel including applying an inverted data signal to the dummy data line to remove a coupling effect formed between a pixel electrode and the main data line.

The present invention provides a method of driving a liquid crystal display panel which can prevent distortion of a data signal by removing the coupling effect between the pixel electrode and the signal line while securing a high aperture ratio through the overlapping formation of the pixel electrode and the signal line. The purpose is.

Description

Driving method of liquid crystal display panel {DRIVING METHOD FOR LIQUID CRYSTAL DISPLAY}

The present invention relates to a method of driving a liquid crystal display panel, and more particularly, to a method of driving a liquid crystal display panel capable of removing a coupling effect between a pixel electrode and a signal line.

Liquid crystal displays (LCDs) inject a liquid crystal material between two substrates provided with electrodes and apply different potentials to the two electrodes to form an electric field to change the arrangement of liquid crystal molecules, thereby improving light transmittance. It is a device which displays an image by adjusting.

In a liquid crystal display (COA) structure, a thin film transistor (TFT) is formed on a lower substrate, a color filter layer is formed on the thin film transistor, and a contact hole is formed in the color filter layer. The pixel electrode is formed on the filter layer. In addition, since the black matrix except the color filter layer and the common electrode are formed on the upper substrate facing the lower substrate, the opening has a high aperture ratio. In particular, since the color filter layer may be formed using an organic layer having a low dielectric constant, a coupling capacitance between the pixel electrode and the signal line may be further reduced. Therefore, by forming the pixel electrode to overlap the signal line, the area of the pixel electrode can be increased to further increase the aperture ratio.

However, it is difficult to completely remove the coupling capacitance between the pixel electrode and the signal line even through the above-described organic film formation, so that the data signal (gradation voltage) transmitted through the signal line during long time image driving or outputting a specific image is distorted. There is a problem. For example, in a normally black mode, when a yellow pattern, which is a combination of red and green, is output to a tricolor pixel composed of red, green, and blue pixels, both data lines of the red pixel may be separated. While all are white driven, only one data line is white driven in the green pixel. That is, since the coupling effect of the red pixel is greater than that of the green pixel, the voltage level of the red pixel is increased. As a result, the red pixel becomes darker and the green pixel is more brightly recognized, and an yellow pattern close to green is output. As described above, the conventional liquid crystal display has a problem in that a data signal is distorted when driving an image for a long time or when outputting a specific image. Due to the distortion of the data signal, display defects such as deterioration of gamma characteristics, vertical cross talk, and vertical streaks may occur.

SUMMARY OF THE INVENTION The present invention is to overcome the above-mentioned problems. The present invention can prevent distortion of a data signal by removing a coupling effect between a pixel electrode and a signal line while ensuring a high aperture ratio through overlapping formation of the pixel electrode and a signal line. It is an object of the present invention to provide a method for driving a liquid crystal display panel.

According to an aspect of the present invention, there is provided a method of driving a liquid crystal display panel, wherein the main data line includes a main data line and a dummy data line overlapping a pixel electrode. Applying a normal data signal to the dummy data line, and applying an inverted data signal to the dummy data line to remove a coupling effect formed between the pixel electrode and the main data line due to the application of the normal data signal. do.

The inversion data signal is preferably a signal generated by inverting the polarity of the normal data signal by the polarity inversion signal.

The normal data signal and the inverted data signal are preferably signals having a period and an amplitude and opposite polarities.

Preferably, the normal data signal and the inverted data signal are applied through immediately adjacent main data lines and dummy data lines.

According to another aspect of the present invention for achieving the above object, a liquid crystal display panel includes a gate line extending in a first direction, a main data line extending in a second direction and a dummy data line formed adjacent thereto, An organic layer formed on the data line and the dummy data line, and a pixel electrode formed on the organic layer, the pixel electrode formed to overlap at least one of the gate line, the main data line, and the dummy data line; Part of the silver is formed of the same metal as the gate line, and part of the silver is formed of the same metal as the main data line, and both sides thereof are connected to the contact structure.

The organic layer preferably includes a red color filter, a green color filter, and a blue color filter.

The dummy data line may include a data pad formed at one end thereof, and a portion adjacent to the data pad may be formed of a metal such as a gate line.

The liquid crystal display panel further includes a thin film transistor connected to the main data line.

The present invention forms an organic layer between the pixel electrode and the signal line to reduce the coupling effect between the pixel electrode and the signal line. Therefore, by forming the pixel electrode to overlap the signal line, the area of the pixel electrode can be increased to further increase the aperture ratio.

In addition, the present invention cancels the coupling effect by additionally forming a dummy data line right next to the data line and applying a normal data signal and its inverted data signal, respectively. Accordingly, display defects such as deterioration of gamma characteristics, vertical crosstalk, and vertical streaks due to distortion of the data signal do not occur even when driving images for a long time or when outputting a specific image.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like reference numerals in the drawings refer to like elements.

1 is a partial plan view of a lower substrate according to an embodiment of the present invention, Figure 2 is a partial cross-sectional view of the lower substrate according to the AB, BC, CD line of Figure 1, Figure 3 is an AB, BC, CD line of Figure 1 A partial cross-sectional view of the upper substrate corresponding to the.

1 to 3, the liquid crystal display panel includes an upper substrate 200 on which the common electrode 220 is formed, a lower substrate 100 on which the pixel electrode 160 is formed, and is opposite to the upper substrate 200. A liquid crystal layer (not shown) is formed between the substrate 200 and the lower substrate 100.

The upper substrate 200 includes a light transmissive insulating substrate 210, a black matrix 220 formed on the substrate 210, and a common electrode 240 formed on the black matrix 220.

The black matrix 220 blocks light leakage between adjacent pixel areas. The black matrix 220 may be formed to correspond to the formation region of the signal line formed on the lower substrate 100 and the unformation region of the color filter.

An over coat layer 230 may be formed between the black matrix 220 and the common electrode 240 to improve adhesion and flatness of an interface. In addition, a column spacer (not shown) for maintaining a cell gap may be formed on the overcoat layer 230. The column spacer may be formed on any one of the upper and lower substrates 200 and 100. When the column spacer is formed on the upper substrate 200, the column spacer may be formed on the upper layer of any one of the black matrix 220, the overcoat layer 230, and the common electrode 240. Can be formed.

The lower substrate 100 may include a transparent insulating substrate 110, a plurality of gate lines GL extending in one direction on the substrate 110, and a plurality of data lines extending in other directions on the substrate 110. And a thin film transistor T, a pixel electrode 192, a storage electrode (not shown), and the like, which are formed in an intersection region of the plurality of gate lines GL and the plurality of data lines DL. The pixel area is defined by the intersection area, but is not limited thereto. The pixel area may extend to the peripheral area of the intersection area.

Gate pads 124 are formed at one end of each gate line GL, and data pads 166-1 and 166-2 are formed at one end of each data line DL. In particular, the plurality of data lines DL may include a plurality of main data lines DL-M for applying a normal data signal (or gray voltage) and a plurality of dummy data lines DL- for applying an inverted data signal. D). In this embodiment, it is preferable that a pair of data lines, that is, one main data line DL-M and a dummy data line DL-D are allocated to each pixel. Of the pair of data lines, only the main data line DL-M is connected to the thin film transistor T, and a substantial data signal is applied to the pixel electrode 190 through the main data line DL-M.

The thin film transistor T is disposed on the gate electrode 122, the insulating layer 132, the active layer 142, and the ohmic contact layer 152 formed on the gate electrode 122, and the ohmic contact layer 152 separated on both sides. And a source electrode 162 and a drain electrode 164 formed at each of the two electrodes. The gate electrode 122 is connected to the gate line GL, the source electrode 162 is connected to the main data line DL-M, and the drain electrode 164 is connected to the pixel electrode through the contact hole 182. 192 is connected. Therefore, when a predetermined gate signal is applied to the gate electrode 122 through the gate line GL, a conductive channel is formed in the active layer 142, and thus a predetermined normal data signal (or gray scale) through the main data line DL-M. Voltage) may be applied to the pixel electrode 182.

The pixel electrode 192 forms the liquid crystal capacitor Clc together with the common electrode 250 formed on the opposing substrate 200. The liquid crystal capacitor Clc controls the arrangement direction of the liquid crystal layer by charging the data signal.

The passivation layer 172 and the color filter layer 180 are formed between the thin film transistor T and the pixel electrode 192. The color filter layer 180 may be configured to uniquely display any one of the three primary colors, and display a natural color through a combination thereof. For example, the color filter 180 may include a red color filter 180R, a green color filter 180G, and a blue color filter 180B in a stripe structure, a delta structure, and a mochaic structure. It may be formed of any one structure. In particular, the pixel electrode 192 according to the present exemplary embodiment may be formed to overlap at least a portion ΔS of the signal line, that is, the gate line GL and the data line DL. To this end, it is preferable that the color filter layer 180 is formed of an organic material having a low dielectric constant, for example, a benzene cyclobutane (BCB), a siloxane polymer (SOG), a polyimide resin, or the like. The organic color filter layer 180 reduces the coupling effect between the pixel electrode 192 and the signal lines GL and DL. Therefore, by forming the pixel electrode 192 to overlap the signal lines GL and DL, the area of the pixel electrode 192 can be increased to further increase the aperture ratio.

The sustain electrode (not shown) is connected to a sustain line (not shown) extending substantially in parallel with the gate line GL, and receives a reference voltage such as a common voltage. The storage electrode forms a storage capacitor Cst together with the pixel electrode 192 formed thereon, and serves to hold the data signal charged in the pixel electrode 192 until the next data signal is charged. Of course, the sustain capacitor Cst may be omitted as necessary.

On the other hand, the gate electrode 122, the gate line (GL) and the gate pad 124 is preferably all formed together in the same step, the gate wiring includes all of them. In addition, the source electrode 162, the drain electrode 164, the data line DL, and the data pads 166-1 and 166-2 are preferably formed together in the same step, and the data wiring includes all of them. . In addition, it is preferable that the auxiliary gate pad 194 and the auxiliary data pads 196-1 and 196-2 are further formed on the gate pad 124 and the data pads 166-1 and 166-2, and these are the pixel electrodes 192. It is preferably formed together in the same step. However, the dummy data line DL-D and its data pad 166-2 may be the same as the main data line DL-M in an area where a fine wiring pitch is required, such as a fan out area. Since it may be difficult to form in layers, it is preferable to form in different layers using the metal for gate wiring. That is, the dummy data line DL-D and the data pad 166-2 thereof are preferably formed of a data wiring metal in the display area, and formed of a gate wiring metal outside the display area. At this time, it is preferable that the signal wires at both sides formed in different layers are connected through the contact hole 188. Here, the display area means an area in which an image display is possible in the liquid crystal display panel.

In addition, the insulating layer 122 is formed between the gate line and the data line, and the passivation layer 172 and the organic layer 180 are formed between the data line and the pixel electrode 192 for electrical connection between the upper and lower wirings. In addition, for electrical connection between the upper and lower wirings, a plurality of contact holes 182, 184, 186-1, 186-2, and 188 are formed to expose the lower wiring by removing a portion of the lower layer. For example, a contact hole 182 for connecting the drain electrode 164 and the pixel electrode 192, a contact hole 184 for connecting the gate pad 124 and the auxiliary gate pad 194, and a data pad ( Contact holes 186-1 and 186-2 for connecting the 186-1 and 186-2 and the auxiliary data pads 196-1 and 196-2, and dummy gate lines DL-D on both sides formed in different layers. A contact hole 188 and the like are formed.

The liquid crystal layer (not shown) is formed by injecting liquid crystal between the upper and lower substrates 200 and 100 bonded to each other by a predetermined distance. The liquid crystal layer of the present embodiment is preferably oriented such that the long axis of the liquid crystal molecules is perpendicular to the upper and lower substrates 200 and 100, and the tilting direction of the liquid crystal molecules is preferably dispersed in various directions. That is, it is preferably formed in a multi-domain structure. Although not shown, in order to form such a multi-domain structure, at least one of the opposite surfaces of the upper and lower substrates 200 and 100, for example, the common electrode 250 and the pixel electrode 192, may be regulated in a liquid crystal alignment such as a cutout pattern or a protrusion pattern. Means may be provided. The liquid crystal alignment regulating means serves to further improve the viewing angle by dispersing the inclination direction of the liquid crystal molecules in various directions.

On the other hand, it is difficult to completely remove the coupling capacitance Cdp between the pixel electrode 192 and the signal lines GL and DL through the color filter layer 180 described above. The data signal may be distorted by the ring capacitance Cdp. In order to solve this problem, the liquid crystal display according to the present exemplary embodiment applies the normal data signal D1 to the main data line DL-M, and inverts the data signal D2 to the immediately adjacent dummy data line DL-D. Is applied to drive each pixel so that the coupling capacitance Cdp generated by these signals cancels each other out. Hereinafter, a driving method of the liquid crystal display will be described in detail.

The liquid crystal display according to the exemplary embodiment of the present invention includes the above-described liquid crystal display panel, a gate driver for driving the plurality of gate lines GL, a data driver for driving the plurality of data lines DL, and controlling them. It includes a timing controller.

The timing controller processes the image data signal RGB and its control signals, ie, the vertical synchronization signal Vsync and the horizontal synchronization signal Hsync, which are input from the outside, in accordance with the operating conditions of the liquid crystal display panel, thereby making internal image data. A signal RGB and a control signal thereof, that is, a gate control signal and a data control signal, are generated. The gate driver sequentially applies a gate signal to the plurality of gate lines GL according to a gate control signal. The data driver applies a data signal to each data line DL according to the data control signal. In this case, the data signal is a signal obtained by converting the internal image data signal RGB into an analog form, and polarity may be inverted for each column according to the inversion signal RVS among the data control signals (column inversion). On the other hand, the data signal is applied to the pixel turned on by the gate signal is applied to control the display operation of each pixel.

4 is a conceptual diagram illustrating pixel arrangement of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 5 is a waveform diagram illustrating data voltages applied to each pixel of FIG. 4. Here, the D1 signal of FIG. 5 is a signal that causes a tricolor pixel composed of a red pixel, a green pixel, and a blue pixel to output an yellow pattern, and the D2 signal of FIG. 5 is an inverted signal of the D1 signal.

4 and 5, each normal data signal D1 is applied to each main gate line DL-M. That is, the red data signal D1 -R is applied to the main gate line DL _n -M of the red pixel R, and the green data signal D1 is applied to the main gate line DL _{n +1} -M of the green pixel G. -G), the blue data signal D1-B is applied to the main gate line DL _{n +2} -M of the blue pixel B. In this case, some coupling capacitance may occur due to the overlap of each of the main data lines DL-M to which each data signal D1 is applied and each of the pixel electrodes 192. Subsequently, an inverted data signal D2 is applied to each dummy gate line DL-D. That is, the inverted red data signal D2-R is applied to the dummy gate line DL _n -D of the red pixel R, and the inverted green is applied to the dummy gate line DL _{n +1} -D of the green pixel G. The inverted blue data signal D2-B is applied to the data signal D2-G and the dummy gate line DL _{n +2} -D of the blue pixel B. At this time, the normal data signal D1 and the inverted data signal D2 are signals whose amplitude and period have only opposite polarities. Therefore, the coupling capacitance generated when the normal data signal D1 is applied is canceled out. Accordingly, display defects such as deterioration of gamma characteristics, vertical crosstalk, and vertical streaks due to distortion of the data signal do not occur even when driving images for a long time or when outputting a specific image.

As mentioned above, although this invention was demonstrated with reference to the above-mentioned Example and an accompanying drawing, this invention is not limited to this, It is limited by the following claims. Therefore, it will be apparent to those skilled in the art that the present invention may be variously modified and modified without departing from the technical spirit of the following claims.

1 is a partial plan view of a lower substrate according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the lower substrate taken along lines A-B, B-C and C-D of FIG.

3 is a partial cross-sectional view of the upper substrate corresponding to lines A-B, B-C, and C-D of FIG.

4 is a conceptual diagram illustrating pixel arrangement of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 5 is a waveform diagram illustrating a data voltage applied to each pixel of FIG. 4. FIG.

<Explanation of symbols for the main parts of the drawings>

100: lower substrate 122: gate electrode

132: insulating film 142: active layer

152: ohmic contact layer 162: source electrode

164: drain electrode 172: protective film

180: color filter layer 192: pixel electrode

200: upper substrate 220: black matrix

230: overcoat film 240: common electrode

Claims (1)

A driving method of a liquid crystal display panel in which a main data line and a dummy data line partially overlapped with a pixel electrode are formed. Applying a normal data signal to the main data line; Applying an inverted data signal to the dummy data line to remove a coupling effect formed between the pixel electrode and the main data line due to the application of the normal data signal; Method of driving a liquid crystal display panel comprising a.

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