KR101224456B1 - In-plane switching mode liquid crystal display and method for repairing the same - Google Patents

Abstract

Provided are an electric field type liquid crystal display device and a repair method thereof for driving visual defects by interlocking a bad pixel with an adjacent normal pixel. The liquid crystal display includes a transparent insulating substrate having first and second pixels defined therein, a plurality of gate lines and data lines in the vertical and horizontal directions crossing each other, a dual type thin film transistor disposed at each pixel, an image connected to the thin film transistor, The upper and lower common electrodes configured to intersect the lower pixel electrode, the upper and lower pixel electrodes, the common line disposed between the first and second pixels, and the overlap regions at both ends of the upper and lower common electrodes. And a repair pattern configured to overlap the lower pixel electrode of one pixel and the upper pixel electrode of the second pixel, respectively.

Liquid Crystal Display, Array Board, Repair Process, Laser Welding

Description

Transverse electric field type liquid crystal display device and its repair method {In-plane switching mode liquid crystal display and method for repairing the same}

1 and 2 are plan views of an array substrate for a liquid crystal display device according to the prior art.

FIG. 3 is a diagram for describing an inspection process that is generally performed after completing an array substrate of a liquid crystal display.

4 is a plan view illustrating an array substrate in a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 5 is a diagram for describing a repair process of FIG. 4.

FIG. 6 is a cross-sectional view illustrating a change in a line III according to the repair process of FIG. 5.

7 is a flowchart illustrating a repair method of a liquid crystal display according to an exemplary embodiment of the present invention.

8 is a comparison table for explaining the effects of the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

100: transparent insulating substrates P1, P2,... Pixel

110: gate line 120: data line

121: source electrode 122: drain electrode

130: common line 131: upper common electrode

132: lower common electrode 140: upper pixel electrode

141: lower pixel electrode 150: repair pattern

The present invention relates to a liquid crystal display and a repair method thereof, and more particularly, to a transverse electric field type liquid crystal display device and a repair method thereof.

The liquid crystal display device forms a liquid crystal layer having anisotropic dielectric constant between the color filter substrate, which is the upper and lower transparent insulating substrates, and the array substrate, and then adjusts the intensity of the electric field formed in the liquid crystal layer to change the molecular arrangement of the liquid crystal material. The display device expresses a desired image by adjusting the amount of light transmitted through the color filter substrate. As the liquid crystal display, a thin film transistor liquid crystal display (TFT LCD) using a thin film transistor (TFT) as a switching element is mainly used.

1 and 2 are plan views of an array substrate for a liquid crystal display according to the related art, and show an array substrate used in a twisted nematic (TN) structure and an in-plane switching (IPS) structure, respectively.

A conventional array substrate is composed of a plurality of pixels defined by gate lines 10 and 40 and data lines 20 and 50 orthogonal to each other, as shown in FIGS. 1 and 2. Source electrodes 21 and 51 and drains facing each other with gate electrodes 11 and 41 extending from 40, semiconductor layers (not shown) on gate electrodes 11 and 41, and semiconductor layers (not shown) interposed therebetween. Electrodes 22 and 52 are formed to form a thin film transistor.

In the case of the TN structure, as illustrated in FIG. 1, the pixel electrode 30 is formed to be connected to the drain electrode 22 to display an image by generating an electric field perpendicular to a common electrode (not shown) on the color filter substrate.

In addition, referring to FIG. 2, in the case of the IPS structure, the gate line 40 and the common line 70 are arranged in parallel in the horizontal direction on the array substrate, and the data line 50 is disposed in the vertical direction in the gate line 40. And perpendicular to the common line 70.

The common electrodes 71 branched from the common line 70 and the pixel electrodes 61 connected to the drain electrode 52 are alternately formed to generate an electric field in a horizontal direction.

FIG. 3 is a diagram for describing an inspection process that is generally performed after completing an array substrate of a liquid crystal display.

After the array substrate is completed through the TFT array process (S10), the array test process (S11) is performed before manufacturing the liquid crystal panel by performing the liquid crystal cell process in which the array substrate and the color filter substrate are bonded and the liquid crystal layer is formed. Through the inspection of the defective array substrate is completed.

In the array test process S11, a constant test signal is applied to the gate pad and the data pad on the completed array substrate to check the on / off state of the thin film transistors formed on the array substrate. When the thin film transistors are in the on state, the test signal is applied through the data lines on the data pad to check the pixel lighting state.

If a defective product is found through such an array test process (S11), the defective product inspection operation (S12) is performed to determine the form of the defect, whether repair is possible, etc. using the naked eye or an optical apparatus.

As a result of the defective product inspection, when the degree of defect is severe and the number of the defective pixels is greater than the reference value, the repair process is not performed. When the number of the defective pixels is in the reference value region, the repair process S13 is performed for each defective pixel. .

In the case of a defective pixel, the pixel is always on and appears as a bright point on the liquid crystal panel, or is always dark and appears as a dark spot on the liquid crystal panel, and the pixel which is always on is repaired using a laser. Step S13 is performed to darken the data voltage so as not to be applied to the pixel electrode.

That is, in the repair process (S13), when there are defective pixels that are always in the on state, patterning is normalized by using a laser again to normalize them, or as shown in FIGS. 1 and 2, portions of the drain electrodes 22 and 52 of the thin film transistor. After cutting (a1, a2), the pixel electrode 30 is brought into contact with the gate line 10, or the pixel electrode 61 is brought into contact with the common electrode 71 to darken.

However, when the repair process (S13) is performed in this manner, the repaired pixels always exist only as dark spots, and the pixels of the darkened spots are not easily recognized as compared to the bright spots but are easily recognized by the user. There was this.

In addition, when the drain electrodes 22 and 52 of the thin film transistor connected to the pixel electrodes 30 and 61 are cut in order to repair the pixel electrodes 30 and 61 (a1 and a2), adjacent source electrodes 21 and 51 are cut. ) And a short between the drain electrodes 22 and 52 and the gate electrodes 11 and 41 easily occurs.

Accordingly, an object of the present invention is to provide a transverse electric field type liquid crystal display device in which a bad point is not easily recognized in a general image by visually making defects by driving a bad pixel cooperatively with an adjacent normal pixel.

In addition, another technical problem to be achieved by the present invention is to provide a transverse electric field type liquid crystal display device which can easily perform a repair process not only in the array substrate state before bonding to the liquid crystal panel but also in the liquid crystal panel state after the bonding.

Another object of the present invention is to provide a repair method of a transverse electric field type liquid crystal display device capable of efficiently repairing such a liquid crystal display device.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to an aspect of the present invention, there is provided a transverse electric field type liquid crystal display device comprising: a transparent insulating substrate on which first and second pixels are adjacent to each other; a plurality of data lines formed in a vertical direction on the transparent insulating substrate; A plurality of gate lines formed in the pixel in a horizontal direction so as to intersect the plurality of data lines, and disposed at intersections of the plurality of gate lines and the plurality of data lines, respectively, and including a gate electrode, a semiconductor layer, a source electrode, and a pair of A dual type thin film transistor having a drain electrode, upper and lower pixel electrodes connected to the pair of drain electrodes, and upper and lower common electrodes disposed to alternate with the upper and lower electrodes, respectively, the first pixel and the first electrode. It is formed in the horizontal direction between the two pixels, the lower common electrode of the first pixel and the upper common of the second pixel A common line connecting electrodes to each other, and disposed between the first pixel and the second pixel, and overlap regions of both ends thereof overlap the lower pixel electrode of the first pixel and the upper pixel electrode of the second pixel, respectively; It includes a repair pattern.
In addition, a repair method of a transverse electric field type liquid crystal display device according to the present invention includes a) first and second switches which are respectively switched by a dual type thin film transistor having a gate electrode, a semiconductor layer, a source electrode and a pair of drain electrodes. A pixel is formed, and a repair pattern is formed between the first and second pixels, and both ends of the repair pattern have an array substrate overlapping the lower pixel electrode of the first pixel and the upper pixel electrode of the second pixel. Manufacturing, b) detecting a bad pixel by applying a test signal to the first and second pixels, and c) cutting the thin film transistor of the first pixel when the first pixel is a bad pixel. And d) forming both ends of the repair pattern overlapping the first pixel as the bad pixel and the second pixel as the normal pixel, and the second pixel as the lower pixel electrode of the first pixel. In comprises a step of electrical contact with the top pixel electrode.

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Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention, and methods of achieving the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. Like reference numerals refer to like elements throughout.

Hereinafter, a transverse electric field type liquid crystal display device and a repair method thereof according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a plan view illustrating an array substrate in a liquid crystal display according to an exemplary embodiment of the present invention.

The liquid crystal display according to the exemplary embodiment of the present invention includes a plurality of pixels, such as P1 and P2 illustrated in FIG. 4, and the common lines 130 in the horizontal direction and the data line 120 in the vertical direction intersecting with each other. The pixels may be divided into regions, and the gate lines 110 may be formed in parallel with the common lines 130 for each pixel to cross the data lines 120.

A dual type thin film transistor is formed at an intersection of the gate line 110 and the data line 120. The thin film transistor includes a gate electrode defined as a partial region on the gate line 110, a semiconductor layer on the gate electrode (not shown), a source electrode 121 branched from the data line 120, and a semiconductor layer (not shown). And a pair of drain electrodes 122 disposed so as to face each other with the source electrode 121.
This dual type thin film transistor has a ＇H＇ type source electrode 121, as shown in FIG. A pair of drains are disposed on both upper and lower sides of the source electrode 121 to face the source electrode 121 at regular intervals, and the portion facing the source electrode 121 has a ＇I＇ type structure. It has an electrode 122.
The pair of drain electrodes 122 are respectively disposed in the upper pixel electrode 140 and the lower pixel electrode 141 having a symmetrical shape with the gate line 110 interposed therebetween in one pixel (eg, P1). Connected.

The upper and lower common electrodes 131 and 132 are alternately disposed with the upper and lower pixel electrodes 140 and 141 to form an electric field in a horizontal direction.

Some areas of the common line 130 are defined as a repair area R, and an outline of the common line 130 is separated from other areas of the common line 130 on the repair area R, and only one side thereof is connected to the common line 130. An island-shaped repair pattern 150 is formed.

The repair pattern 150 is disposed between two adjacent pixels such as P1 and P2 so that the overlap regions of both ends overlap each other with the pixel electrodes of the adjacent pixels. In the case of FIG. 4, the repair pattern 150 is formed such that both ends thereof are interposed between the lower pixel electrode 141 of P1, which is a pixel located above, and the upper pixel electrode 140 of P2, a pixel located below.

The repair pattern 150 has a structure in which a defective pixel is easily changed into an independent island-shaped pattern when a defective pixel is detected, and two adjacent pixels, P1 and P2, as shown in the repair region R of FIG. 4. All of them should include an overlap area overlapping with the repair pattern 150.
Here, in the repair pattern 150, it is efficient to allow the overlap regions on both sides to overlap with the same area by having the two pixels have a symmetrical shape in an adjacent direction (vertical direction in FIG. 4).

On the other hand, each pixel is formed in a structure in which the center is bent so that the upper and lower pixel electrodes 140 and 141 and the upper and lower common electrodes 131 and 132 have a predetermined angle with respect to the gate line 110 as shown in FIG. 4. can do. In this structure, as the transverse electric fields in different directions are formed at the upper and lower portions of the gate line 110, domains having different arrangement directions of the liquid crystal molecules are divided, so that the transverse electric field on the array substrate is formed only in one direction. Compared to the case of the present invention, the color shift phenomenon is improved, the viewing angle characteristic is improved, and the response speed is increased.

This array substrate is advantageous when the lateral electric field mode is applied to a large model television or the like as a transverse electric field structure of one pixel 2 TFT, and is manufactured and used as a liquid crystal panel including a color filter substrate and a liquid crystal layer formed between the two substrates. do. The array substrate is driven to form a horizontal electric field between the upper common electrode 131 and the upper pixel electrode 140, the lower common electrode 132, and the lower pixel electrode 141 to control the alignment of the liquid crystal layer for each pixel. The color filter substrate includes red, green, and blue color filters, and transmits light for each wavelength according to the alignment of the liquid crystal material to display an image.

FIG. 5 is a view for explaining the repair process of FIG. 4, and FIG. 6 is a cross-sectional view illustrating a change in a line II according to the repair process of FIG. 5.

When the number of defective pixels on the array substrate is in the reference region, the repair process is performed to visually defect the defective pixels using the structure of the repair pattern 150.

For example, in the structure of FIG. 4, assuming that P1 is a bad pixel and P2 adjacent to P1 is a normal pixel, first, the drain electrode of the thin film transistor provided in P1 through laser cutting. Disconnect (122).

In addition, the repair pattern 150 formed between the lower pixel electrode 141 of P1 and the upper pixel electrode 140 of P2 is disconnected from the common line 130 by laser cutting of c1 so that two pixels P1 and P2 are disconnected. The pixel electrodes 140 and 141 and the repair pattern 150 overlapping the pixel electrodes 140 and 141 through laser welding of c2 and c3 are formed to be independent island-shaped patterns linking the pixel electrodes 140 and 141 therebetween. The overlap region of is shorted to repair P1 which is a bad pixel.

Then, as illustrated in FIG. 6, the pixel electrodes 140 and 141 of P1 and P2 that are separated from each other are connected to each other through the repair pattern 150, and P1, which is a bad pixel, has a data voltage applied to P2, which is a normal pixel. By driving together, P1 and P2 display the same gray level, thereby enabling visual imperfections.
In this case, as illustrated in FIG. 6, the repair pattern 150 is formed on the transparent insulating substrate 100 that is coplanar with the common line 130 positioned between the two pixels P1 and P2.

Referring to FIG. 6, in the state d1 before the repair process, the repair pattern 150 in an isolation state is formed on the transparent insulating substrate 100, and P1 and P2 are disposed with the protective film 101 interposed therebetween. Each of the pixel electrodes 140 and 141 is formed, so that the common voltage is applied to the repair pattern 150, and each data voltage is applied to the pixel electrodes 140 and 141.

In the state d2 after the repair process, the pixel electrodes 141 and 140 of P1 and P2 are in electrical contact with each other through points c2 and c3 so that the data voltage applied to the upper pixel electrode 140 of P2 is lower than P1. The pixel electrode 141 is transferred to the pixel electrode 141.

4 to 6 illustrate a case in which one repair pattern 150 is formed between two adjacent pixels as in P1 and P2, and one side of the formed repair pattern 150 is connected to the common line 130. However, the present invention is not limited thereto and may be modified in various forms.

For example, in order to secure contact characteristics during the repair process, a plurality of such repair patterns 150 may be formed, or the repair patterns 150 may be formed in an original island pattern to perform laser cutting of c1. It will be possible to repair with only laser welding of c2 and c3 without the need for this.

Conventionally, when there are defective pixels, a pattern is formed again with a laser or darkened as it is. However, in the present invention, the repair pattern 150 is formed in advance in the array process, and the laser cutting is not necessary during the repair process. The defective pixels can be repaired using only the laser welding. Therefore, there is an advantage that the repair process can be performed not only in the array substrate state but also in the state in which the array substrate is manufactured as the liquid crystal panel through the liquid crystal cell process.

FIG. 7 is a flowchart illustrating a repair method of a liquid crystal display according to an exemplary embodiment of the present invention. Hereinafter, a case in which P1 is a bad pixel and P2 is a normal pixel in an array substrate having the structure of FIG. 4 will be described. Shall be.

First, a TFT array process for manufacturing an array substrate through steps S100 to S120, a color filter process for manufacturing a color filter substrate, and a liquid crystal cell process for bonding two substrates together and forming a liquid crystal layer therebetween are performed. Will be configured.

Here, the array substrate includes a plurality of pixels switched by a dual type thin film transistor including a gate electrode serving as a partial region on the gate line 110, a source electrode 121, and a pair of drain electrodes 122. P1, P2, ...).
In addition, repair patterns 150 are formed between adjacent pixels, and both ends of each repair pattern 150 are respectively disposed at pixel electrodes 140 and 141 between adjacent pixels (eg, P1 and P2). It is configured to overlap.
Taking two pixels, P1 and P2 as an example, both ends of the repair pattern 150 positioned between P1 and P2 overlap the lower pixel electrode 141 of P1 and the upper pixel electrode 140 of P2 by a predetermined area. do.

Here, the repair patterns 150 on the array substrate may be formed in a form connected to the common lines 130 applying the common voltage Vcom to each pixel P1, P2,..., Or in an independent island pattern. .

Red, green, and blue color filters, a black matrix, and the like are formed on the color filter substrate, and light is transmitted for each wavelength in accordance with driving of the array substrate to display an image.

The repair process according to the present invention can be applied to both the array substrate state and the liquid crystal panel state, and when the repair process is performed in the array substrate state, steps S110 and S120 are omitted.

Next, in operation S130, a bad signal P1 is detected by applying a test signal to the pixels P1, P2,..., On the array substrate.

Next, in operation S140, the drain electrodes 122 of the thin film transistor included in the defective pixel P1 are disconnected by laser cutting to be connected to the upper and lower pixel electrodes 140 and 141 in the defective pixel P1. Do not

Next, in operation S150, both ends of the repair pattern 150 configured to overlap the bad pixel P1 and the pixel electrodes 140 and 141 of the normal pixel P2 adjacent to the bad pixel P1 are lasered. By welding, the pixel electrodes 140 and 141 of the two pixels P1 and P2 are electrically linked through the repair pattern 150.

In the case where the repair patterns 150 on the array substrate are configured to be connected to the common lines 130, the common lines 130 are connected to the repair patterns 150 provided in the bad pixels P1 using a laser before step S140. And disconnecting from).

As described above, by driving the defective pixel P1 with the normal pixel P2 adjacent to the upper or lower position, the visual defect may be realized such that the defect is not recognized when the image is displayed.

8 is a comparison table for explaining the effect of the present invention, comparing the recognition characteristics when the upper and lower pixels (up and down adjacent adjacent pixels and normal pixels) by applying the present invention and the dark point according to the prior art It is.

If white, gray, or black levels are displayed on the screen, when repaired and darkened according to the prior art, they are recognized as defective in all gray except the black level as shown on the right. In the case where the upper and lower pixels are linked according to the invention, no defective point is recognized in any gray as in the left side.

When a line is displayed on the screen, the defect is recognized only when the defective pixel is caught directly above the line in the present invention, whereas the defect is recognized in all grays except the black level in the prior art.

When a picture having various grays is displayed on the screen, in the present invention, since a bad pixel displays gray similar to an adjacent normal pixel, it is not well recognized as a bad even at the boundary of the image. This is recognized.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

Therefore, it should be understood that the above-described embodiments are provided so that those skilled in the art can fully understand the scope of the present invention. Therefore, it should be understood that the embodiments are to be considered in all respects as illustrative and not restrictive, The invention is only defined by the scope of the claims.

According to the transverse electric field type liquid crystal display device and the repair method thereof according to the preferred embodiment of the present invention as described above, the defect point is not easily recognized in the general image by visually defecting the defective pixel by cooperatively driving the adjacent pixel. You can do that.

Further, according to the transverse electric field type liquid crystal display device and the repair method thereof according to the preferred embodiment of the present invention, the repair process can be easily performed not only in the array substrate state before bonding to the liquid crystal panel but also in the liquid crystal panel state after the bonding. .

Claims (13)

A transparent insulating substrate on which first and second pixels adjacent to each other are defined; A plurality of data lines formed in the vertical direction on the transparent insulating substrate and a plurality of gate lines formed in the pixel to intersect the plurality of data lines; A dual type thin film transistor disposed at an intersection of each of the plurality of gate lines and the plurality of data lines and provided with a gate electrode, a semiconductor layer, a source electrode, and a pair of drain electrodes; Upper and lower pixel electrodes connected to the pair of drain electrodes, and upper and lower common electrodes disposed to alternate with the upper and lower pixel electrodes; A common line formed in a horizontal direction between the first pixel and the second pixel and connecting a lower common electrode of the first pixel and an upper common electrode of the second pixel to each other; And A repair pattern disposed between the first pixel and the second pixel and configured such that overlap regions at both ends thereof overlap each of the lower pixel electrode of the first pixel and the upper pixel electrode of the second pixel; When the first and second pixels are all normal pixels, the repair pattern is connected to the common line. When one of the first and second pixels is a bad pixel, the repair pattern is not connected to the common line. It is an independent island pattern, The transverse electric field system liquid crystal display device. The method of claim 1, The repair pattern is, A transverse electric field liquid crystal display device having a symmetrical shape. The method of claim 1, Each of the plurality of gate lines, And a central field of each of the first and second pixels. The method of claim 1, The first and second pixels, A transverse electric field type liquid crystal display device, characterized in that the center portion is bent. delete delete The method of claim 1, The dual type thin film transistor is disconnected from upper and lower pixel electrodes in a bad pixel, and the repair pattern includes a lower pixel electrode of the first pixel and an upper pixel electrode of the second pixel through overlap regions of both sides. The transverse electric field type liquid crystal display device which electrically contacted. a) first and second pixels, each of which is switched by a dual type thin film transistor having a gate electrode, a semiconductor layer, a source electrode and a pair of drain electrodes, are configured, and a repair pattern is formed between the first and second pixels Manufacturing an array substrate on which both ends of the repair pattern are respectively overlapped with a lower pixel electrode of the first pixel and an upper pixel electrode of the second pixel; b) detecting a bad pixel by applying a test signal to the first and second pixels; c) cutting the thin film transistor of the first pixel when the first pixel is a bad pixel; And d) electrically contacting both ends of the repair pattern overlapped with the first pixel as the bad pixel and the second pixel as the normal pixel, to the lower pixel electrode of the first pixel and the upper pixel electrode of the second pixel; Repair method of a transverse electric field type liquid crystal display device containing. 9. The method of claim 8, And after the array substrate is manufactured, manufacturing a liquid crystal panel using the array substrate. 9. The method of claim 8, In step a), The repair pattern may be formed in an independent island pattern or connected to a common line for applying a common voltage to the first and second pixels. And when the repair pattern overlapping the bad pixel is connected to the common line, cutting the repair pattern from the connected common line. 9. The method of claim 8, The repair pattern is, The repairing method of the transverse electric field type liquid crystal display device which is formed so that it may have a symmetrical shape. 9. The method of claim 8, The first and second pixels, A repair method of a transverse electric field type liquid crystal display device, wherein the center portion is formed in a bent shape. 9. The method of claim 8, Step c) is a step of cutting using a laser cutting process (laser cutting), The step d) is a repairing method of a transverse electric field type liquid crystal display device, characterized in that the electrical contact by using a laser welding (laser welding) process.

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