KR101213874B1 - Liquid crystal display panel and repairing method thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display panel and a repair method thereof, which can improve yield by darkening a bright point appearing in a non-uniform alignment region to minimize a defective rate.

The liquid crystal display panel of the present invention comprises an upper and lower substrate facing each other with the liquid crystal interposed therebetween; In a liquid crystal display panel including an upper alignment layer formed on the upper substrate and a lower alignment layer formed on the lower substrate for alignment of the liquid crystal, when foreign matter is mixed in at least one of the upper alignment layer and the lower alignment layer. The alignment film in the region in which the foreign material is mixed together with the mixed foreign material is removed.

Description

Liquid crystal display panel and its repair method {LIQUID CRYSTAL DISPLAY PANEL AND REPAIRING METHOD THEREOF}

1 is a cross-sectional view showing a conventional liquid crystal display panel.

FIG. 2 is a cross-sectional view for explaining alignment failure caused by foreign matter mixed in the lower portion of the alignment film. FIG.

FIG. 3 is a view showing bright spots represented by foreign matters mixed under an alignment layer when an image is implemented. FIG.

4 is a cross-sectional view illustrating a liquid crystal display panel according to an exemplary embodiment of the present invention.

FIG. 5 is a diagram showing the alignment of liquid crystals by an alignment film having a non-uniform alignment region. FIG.

FIG. 6 is a view illustrating an image implemented on an alignment layer of a region in which foreign substances are mixed and a liquid crystal display panel in which foreign substances are removed.

7A and 7B are cross-sectional views illustrating a method for repairing a liquid crystal display panel according to a first embodiment of the present invention.

8 is a cross-sectional view illustrating a repair method of a liquid crystal display panel according to a second exemplary embodiment of the present invention.

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

2, 102: upper substrate 4, 104: black matrix

6, 106: color filter 8, 108: upper alignment film

9, 109: gate electrode 13, 113: pattern spacer

14/47, 114/147: semiconductor layers 16, 116: pixel electrodes

18, 118: common electrode 32, 132: lower substrate

38, 138: lower alignment layer 40, 140: source electrode

42, 142: drain electrode 44, 144: gate insulating film

50, 150: protective film 52, 152: liquid crystal

55, 155: foreign material 160: laser irradiation apparatus

170: grinding bar 171: grinding ball

172: grinding sandpaper

The present invention relates to a liquid crystal display panel and a repair method thereof, and more particularly, to a liquid crystal display panel and a repair method capable of improving yield by darkening a bright point to minimize a defective rate.

In general, a liquid crystal display (LCD) displays an image by adjusting the light transmittance of the liquid crystal according to a video signal. To this end, the liquid crystal display includes a liquid crystal display panel in which liquid crystal cells are arranged in a matrix, and a driving circuit for driving the liquid crystal display panel.

The liquid crystal display is roughly classified into a twisted nematic (TN) mode using a vertical electric field and an in plan switch (IPS) mode using a horizontal electric field according to an electric field driving the liquid crystal.

The TN mode is a mode in which the liquid crystal is driven by a vertical electric field between the common electrode and the pixel electrode disposed opposite to each other on the upper substrate and the lower substrate. The TN mode has a large aperture ratio and a narrow viewing angle. On the other hand, the IPS mode is a mode in which the liquid crystal is driven by a horizontal electric field between the pixel electrode and the common electrode disposed side by side on the lower substrate, and has a large viewing angle, while having a small aperture ratio.

1 is a cross-sectional view showing a conventional TN mode liquid crystal display panel.

Referring to FIG. 1, the liquid crystal display panel of the conventional TN mode includes a black matrix 4, a color filter 6, a common electrode 18, and an upper alignment layer 8 sequentially formed on the upper substrate 2. An upper array substrate (or color filter array substrate), a TFT formed on the lower substrate 32, a lower array substrate composed of the pixel electrode 16 and the lower alignment layer 38, an upper array substrate and a lower array substrate The liquid crystal 52 injected into the inner space is provided therebetween.

Meanwhile, in the IPS mode liquid crystal display panel, the common electrode 18 is formed on the lower substrate 32 and a planarization layer (not shown) is formed on the upper substrate 2 to compensate for the step difference of the color filter 6. .

In the upper array substrate, the black matrix 4 is formed on the upper substrate 2 corresponding to the TFT region of the lower array substrate and the region of the gate lines and data lines not shown, and the color filter 6 is formed. Provide a cell area. The black matrix 4 prevents light leakage and absorbs external light to increase contrast. The color filter 6 is formed over the cell region separated by the black matrix 4 and the black matrix 4. The color filter 6 is formed for each of R, G, and B to implement R, G, and B colors. The common electrode 18 is supplied with a common voltage for controlling the movement of the liquid crystal. The pattern spacer 13 serves to maintain a cell gap between the upper array substrate and the lower array substrate.

In the lower array substrate, the TFTs overlap with the gate electrode 9 formed on the lower substrate 32 together with the gate line, and the semiconductor layers 14 and 47 overlapping the gate electrode 9 and the gate insulating film 44 therebetween. ) And source / drain electrodes 40 and 42 formed together with data lines (not shown) with semiconductor layers 14 and 47 interposed therebetween. This TFT supplies the pixel signal from the data line to the pixel electrode 16 in response to the scan signal from the gate line. The pixel electrode 16 is a transparent conductive material having a high light transmittance and is in contact with the drain electrode 42 of the TFT with the passivation layer 50 interposed therebetween.

The upper or lower alignment layers 8 and 38 for liquid crystal alignment are formed by applying an alignment material such as polyimide and then performing a rubbing process.

Meanwhile, the liquid crystal display panel moves between the thin film and the thin film when the liquid crystal display panel moves to a separate chamber or a third place for forming another thin film or to form another thin film, for example, as shown in FIG. 2. The foreign material 55 often sits between the common electrode 18 and the upper alignment layer 8 of the display panel. At this time, the upper alignment layer 8 positioned to correspond to the foreign material 55 is not rubbed uniformly during the rubbing process by the foreign material 55, and thus, a non-uniform alignment area A is generated in the liquid crystal display panel.

The non-uniform alignment region A generates light leakage in the liquid crystal display panel.

Such light leakage interferes with the light transmittance of the liquid crystal, thereby causing a bright point to appear on the liquid crystal display panel when the LCD is black driven as shown in FIG. 3. In general, when a high gray is implemented, a dark point is seen by one light due to light leakage, and when a low gray is implemented, a bright point is shown by one light due to light leakage. Here, since the human eye is relatively sensitive to the bright point rather than the dark point, a method for minimizing the defective rate of the panel due to the bright point is required by giving a stricter criterion to the bright point than the dark point when determining the failure of the panel.

For this reason, the conventional liquid crystal display panel has an upper portion after the printing or rubbing process of the upper or lower alignment layers 8 and 38 to remove the bright spots caused by the foreign matter 55 mixed in the lower portions of the upper or lower alignment layers 8 and 38. Alternatively, when the foreign material 55 found in the lower portion of the lower alignment layer 8 and 38 is found, the bright spot is removed by removing the entire upper or lower alignment layer 8 and 38 applied and removing the foreign material 55.

However, if the foreign material 55 mixed in the upper or lower alignment layer (8, 38) is removed in this way, waste of polyimide, which is a material of the upper or lower alignment layer (8, 38), is too high, leading to an increase in manufacturing cost. There are disadvantages.

In addition, the foreign matter 55 may be re-mixed under the upper or lower alignment layers 8 and 38 in the process of reapplying the removed upper or lower alignment layers 8 and 38.

Accordingly, an object of the present invention is to provide a liquid crystal display panel and a repair method capable of improving the yield by darkening the bright point appearing in the non-uniform alignment region to minimize the defective rate.

In order to achieve the above object, the liquid crystal display panel according to an embodiment of the present invention and the upper and lower substrates facing each other with the liquid crystal interposed therebetween; In a liquid crystal display panel including an upper alignment layer formed on the upper substrate and a lower alignment layer formed on the lower substrate for alignment of the liquid crystal, when foreign matter is mixed in at least one of the upper alignment layer and the lower alignment layer. The alignment film in the region in which the foreign material is mixed together with the mixed foreign material is removed.

The mixed foreign material and the alignment film of the region in which the foreign material is mixed are removed by irradiating a laser to the alignment film and the foreign material of the region in which the foreign material is mixed.

The mixed foreign material and the alignment film of the region in which the foreign material is mixed are removed by applying direct contact to the alignment film and the foreign material of the region in which the foreign material is mixed.

The direct contact may include grinding the foreign material and the alignment layer of the region in which the foreign material is mixed.

The liquid crystal display panel further includes a thin film transistor formed on the lower substrate and a pixel electrode connected to the thin film transistor.

The liquid crystal display panel further includes a common electrode formed on the lower substrate and forming a horizontal electric field with the pixel electrode.

The liquid crystal display panel further includes a common electrode formed on the upper substrate and forming a vertical electric field with the pixel electrode.

According to one or more exemplary embodiments, a method of repairing a liquid crystal display panel may include preparing an upper substrate on which an upper alignment layer is formed and a lower substrate on which a lower alignment layer is formed; Removing an alignment layer in a region in which foreign materials are mixed with the mixed foreign materials when foreign materials are mixed under at least one of the upper alignment layer and the lower alignment layer; Bonding the upper substrate and the lower substrate such that the upper substrate and the lower substrate face each other with a liquid crystal interposed therebetween.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 8.

4 is a cross-sectional view illustrating a liquid crystal display panel according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the liquid crystal display panel of the TN mode according to an exemplary embodiment of the present invention may include a black matrix 104, a color filter 106, a common electrode 118, and an upper portion sequentially formed on the upper substrate 102. An upper array substrate (or color filter array substrate) composed of an alignment layer 108, a TFT formed on the lower substrate 132, a lower array substrate composed of a pixel electrode 116 and a lower alignment layer 138, and an upper array The liquid crystal 152 is injected into the internal space between the substrate and the lower array substrate.

Meanwhile, in the IPS mode liquid crystal display panel, the common electrode 118 is formed on the lower substrate 132, and a planarization layer (not shown) is formed on the upper substrate 102 to compensate for the step difference of the color filter 106.

In the upper array substrate, the black matrix 104 is formed on the upper substrate 102 in correspondence with the TFT region of the lower array substrate and the region of gate lines and data lines not shown, and the color filter 106 is formed. Provide a cell area. The black matrix 104 prevents light leakage and absorbs external light to increase contrast. The color filter 106 is formed over the cell region separated by the black matrix 104 and the black matrix 104. The color filter 106 is formed for each of R, G, and B to implement R, G, and B colors. The common electrode 118 is supplied with a common voltage for controlling the movement of the liquid crystal. The pattern spacer 113 serves to maintain a cell gap between the upper array substrate and the lower array substrate.

In the lower array substrate, the TFTs overlap with the gate electrode 109 formed on the lower substrate 132 together with the gate line, and the semiconductor layers 114 and 147 overlapping the gate electrode 109 and the gate insulating layer 144 therebetween. ) And source / drain electrodes 140 and 142 formed together with data lines (not shown) with semiconductor layers 114 and 147 interposed therebetween. This TFT supplies the pixel signal from the data line to the pixel electrode 116 in response to the scan signal from the gate line. The pixel electrode 116 is a transparent conductive material having a high light transmittance and contacts the drain electrode 142 of the TFT with the passivation layer 150 therebetween.

The upper or lower alignment layers 108 and 138 for liquid crystal alignment are formed by applying an alignment material such as polyimide and then performing a rubbing process.

In the liquid crystal display panel of the present invention having such a configuration, when the foreign material 155 is mixed under the upper or lower alignment layers 108 and 138, the non-uniform alignment area due to the mixed foreign material 155 ('A in FIG. 2). In order to remove the bright spots caused by the light leakage generated in the reference, the foreign material 155 and the upper or lower alignment layers 108 and 138 of the region where the foreign material 155 are mixed are removed together.

Accordingly, the liquid crystal display panel according to the present invention can remove the non-uniform alignment region generated in the liquid crystal display panel by the foreign matter 155 mixed under the upper or lower alignment layers 8 and 138, and eliminate the non-uniform alignment region. As a result, bright spots can be prevented from occurring when the LCD is black driven.

Referring to the removal of the bright point through the removal of the non-uniform alignment region in detail, the conventional liquid crystal display panel is a liquid crystal 152 as shown in FIG. 5 by the foreign material 155 mixed in the upper or lower alignment layer (108, 138) Disorientation of the light causes the light leakage in the liquid crystal display panel, and the bright spot is generated by the light leakage. However, when the foreign material 155 is mixed in the upper or lower alignment layers 108 and 138, the liquid crystal display panel according to the present invention may have the foreign material 155 and the foreign material 155 mixed in the lower portion of the upper or lower alignment layers 108 and 138. By removing the upper or lower alignment layers 108 and 138 of the mixed region, the alignment of the liquid crystal 152 is prevented as shown in FIG. 4. That is, the liquid crystal display panel of the present invention prevents light leakage generated in the non-uniform alignment region by removing the non-uniform alignment region that disturbs the alignment of the liquid crystal 152, and prevents light leakage to prevent the light leakage of the liquid crystal display panel as shown in FIG. It is possible to remove the bright point appearing when driving the black. As a result, the liquid crystal display panel of the present invention can improve the yield by darkening the bright point to minimize the defective rate.

Hereinafter, a repair method of a liquid crystal display panel according to an exemplary embodiment of the present invention will be described with reference to FIGS. 7A to 8B.

Here, in the repairing method of the liquid crystal display panel according to an exemplary embodiment of the present invention, when the foreign material 155 is mixed under the upper alignment layer 108, the upper alignment layer (the upper alignment layer) of the region where the foreign material 155 and the foreign material 155 is mixed ( Only the case where the 108 is removed together will be described, and the repair method in the case where the foreign material 155 is mixed under the lower alignment layer 138 is the same as the case where the foreign material 155 is mixed under the upper alignment layer 108. same.

Referring to FIG. 7A, in the repairing method of the liquid crystal display panel according to the first exemplary embodiment of the present invention, the laser irradiation apparatus 160 is aligned on the upper alignment layer 108 in the region in which the foreign material 155 is mixed and the foreign material 155. ) Is irradiated with the laser on the upper alignment layer 108 in the region where) is mixed. Then, the upper alignment layer 108 and the foreign material 155 in the area where the laser is irradiated, that is, the area where the foreign material 155 is mixed, are removed together as shown in FIG. 7B. Therefore, the repair method of the liquid crystal display panel according to the embodiment of the present invention can prevent light leakage by removing the non-uniform alignment region caused by the foreign material 155, and can darken the bright point caused by the light leakage. As a result, the liquid crystal display panel of the present invention can improve the yield by darkening the bright point to minimize the defective rate.

In addition, the repairing method of the positive display panel according to the present invention can reduce the waste of the material of the alignment layer compared with the conventional method of removing all the alignment layers in which foreign substances are mixed and removing the foreign substances and then reapplying the aviation layer, thereby manufacturing a repaired liquid crystal display panel. This has the advantage of reducing costs.

In addition, in the repairing method of the liquid crystal display panel according to the second exemplary embodiment of the present invention, the upper alignment layer 108 in the region where the foreign material 155 and the foreign material 155 are mixed may be ground and removed together.

Referring to FIG. 8, the repairing method of the liquid crystal display panel according to another exemplary embodiment of the present invention includes the grinding bar 170 and the grinding ball 171 on the upper alignment layer 108 in the region in which the foreign material 155 is mixed. ) And the grinding device including the grinding sandpaper 172 are aligned and removed together by grinding the upper alignment layer 108 in the region where the foreign material 155 and the foreign material 155 are mixed.

Removal of the foreign material 155 and the upper alignment layer 108 in the region where the foreign material 155 is mixed using the grinding device is sequentially performed by the grinding sandpaper 172. At this time, the grinding sandpaper 172 is moved to the left and right to grind the upper alignment layer 108 in the area where the foreign material 155 and the foreign material 155 is mixed, and at the same time, the grinding ball 171 is By rotating in conjunction with the movement to help the movement of the grinding sandpaper 172.

As described above, the repair method of the liquid crystal display panel according to the exemplary embodiment of the present invention may prevent light leakage by removing the non-uniform alignment region caused by the foreign material 155, and darken the bright point by the light leakage. As a result, the liquid crystal display panel of the present invention can improve the yield by darkening the bright point to minimize the defective rate.

In this case, the repairing method of the liquid crystal display panel according to the second exemplary embodiment of the present invention is not limited to the method using the above-described grinding device, and the upper alignment layer 108 is in direct contact with the upper alignment layer 108 and the foreign material 155. Other methods of removing the foreign matter 155 may also be used.

As described above, in the liquid crystal display panel and the repair method according to the exemplary embodiment of the present invention, when foreign substances are mixed under the upper or lower alignment layer, the mixed foreign substances and the upper or lower alignment layer of the region in which the foreign substances are mixed are removed together. Therefore, the liquid crystal display panel and the repair method of the present invention can remove the non-uniform alignment region generated in the liquid crystal display panel by the foreign matter mixed therein, thereby darkening the bright point on the liquid crystal display panel when black driving the liquid crystal display panel. Can burn. As a result, the liquid crystal display panel and the method of manufacturing the same of the present invention improve the yield by minimizing the defective rate.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (11)

delete delete delete delete delete delete delete Forming a thin film transistor including a gate electrode, a gate insulating film, a semiconductor layer, and a source / drain electrode on a lower substrate; Forming a pixel electrode connected to the drain electrode of the thin film transistor and a passivation layer; Forming a lower alignment layer on an entire surface of a lower substrate including the thin film transistor and the pixel electrode; Forming a black matrix, a color filter, and a common electrode on the upper substrate; Forming a pattern spacer on the common electrode at a position opposite to the thin film transistor; Forming an upper alignment layer on the entire upper substrate including the pattern spacer and the common electrode; When a foreign material is mixed under at least one of the upper alignment film and the lower alignment film, the laser is irradiated to the alignment film in the region where the foreign material is mixed and the foreign material to remove only the region where the foreign material and the foreign material of the alignment film are mixed. Steps; And bonding the upper substrate and the lower substrate so that the upper substrate and the lower substrate face each other with the liquid crystal interposed therebetween. delete delete delete

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