KR20070034803A - Liquid crystal display - Google Patents

Abstract

The present invention relates to a liquid crystal display device. One embodiment of the liquid crystal display according to the present invention, the first insulating film located on the substrate,

A plurality of data lines positioned on the first insulating film, and a semiconductor layer interposed between the first insulating film and the data line. A pixel electrode positioned on the second insulating layer covering the entire surface of the substrate is disposed between the data lines, and an alignment layer covers the entire surface of the substrate. The width of the semiconductor layer is greater than the width of the data line. According to the present invention, rubbing of the alignment layer is uniformly performed on the entire substrate, so that disorientation of liquid crystal molecules does not occur.

Liquid crystal display device, alignment film, rubbing, alignment abnormality

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is a cross-sectional view schematically showing a liquid crystal display device according to the prior art;

2 is a plan view schematically illustrating a general liquid crystal display device;

3 is a cross-sectional view taken along line II of FIG. 2 to schematically illustrate a liquid crystal display according to an exemplary embodiment of the present invention;

4 is a cross-sectional view taken along the line II of FIG. 2 to schematically illustrate a liquid crystal display according to another exemplary embodiment of the present invention;

5A through 5C are cross-sectional views taken along line II of FIG. 2 to explain a method of manufacturing a liquid crystal display according to the present invention.

♧ explanation of the reference numerals for the main parts of the drawing.

110 substrate 120 first insulating film

126: gate line 130: second insulating film

133 semiconductor layer 136 data line

140 pixel electrode 150 alignment layer

T: thin film transistor

The present invention relates to a display device, and more particularly, to a liquid crystal display device.

In general, a flat panel display (FPD) is a display device that provides a thin and flat screen, and is typically used as a liquid crystal display device (LCD), a large digital television, which is widely used as a notebook computer monitor. Or a plasma display panel (PDP) or an organic electroluminescent display (OELD) used in a mobile phone.

In general, a liquid crystal display includes a color filter substrate having a common electrode, a thin film transistor substrate having a pixel electrode, and a liquid crystal layer between two substrates. Different voltages are applied to the common electrode and the pixel electrode, and the arrangement of the liquid crystal molecules is changed by an electric field formed by different voltages, thereby changing the transmittance of the liquid crystal to light.

The electro-optical properties of these liquid crystal molecules largely depend on the formation of the alignment layer and the surface treatment state of the alignment layer by rubbing. That is, in order for the liquid crystal molecules to be uniformly arranged to have uniform display characteristics on the entire screen, an alignment film having a predetermined thickness should be formed on the entire substrate in an alignment film printing process, and a uniform surface treatment should be performed in a rubbing process.

1 is a cross-sectional view schematically showing a liquid crystal display device according to the prior art.

Referring to FIG. 1, the first insulating layer 20 and the semiconductor layer 33 are positioned on the substrate 10. The data line 36 is positioned on the semiconductor layer 33. The second insulating film 30 covering the substrate 10 is positioned. The pixel electrode 40 is positioned at both sides of the data line 36. The alignment layer 50 covering the substrate 10 is positioned again. After the alignment layer 50 is printed, a rubbing process is performed. When rubbing R occurs in the direction of the arrow, a region A that is not rubbed due to a step difference between the semiconductor layer 33 and the data line 36 may be formed. Can be. In this non-rubbing area, an alignment abnormality in which the liquid crystal alignment is not properly performed may occur, and thus an image may not be properly represented.

SUMMARY OF THE INVENTION The present invention has been proposed in consideration of the above-mentioned situation, and a technical problem to be achieved by the present invention is to provide a liquid crystal display device in which an orientation error does not occur.

One embodiment of the liquid crystal display according to the present invention for achieving the above technical problem is a first insulating film located on the substrate; A plurality of data lines positioned on the first insulating layer; A semiconductor layer interposed between the first insulating film and the data line; A second insulating film covering an entire surface of the substrate on which the data line and the semiconductor layer are formed; A pixel electrode on the second insulating layer and disposed between the data lines; And an alignment layer covering an entire surface of the substrate, wherein a width of the semiconductor layer is greater than a width of the data line.

In this embodiment, the second insulating layer may be in contact with the side of the pixel electrode.

Another embodiment of the liquid crystal display according to the present invention includes a first insulating film on the substrate; A plurality of data lines positioned on the first insulating layer; A semiconductor layer interposed between the first insulating film and the data line; A second insulating film covering an entire surface of the substrate on which the data line and the semiconductor layer are formed; A pixel electrode on the second insulating layer and disposed between the data lines; And an alignment layer covering an entire surface of the substrate, wherein the second insulating layer contacts a side of the pixel electrode.

In this embodiment, the semiconductor layer may extend to the side of the pixel electrode.

According to the present invention, since the alignment film is rubbed uniformly as a whole, no abnormality in alignment of the liquid crystal molecules occurs.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey.

In the embodiments herein, the terms first, second, etc. are used only to distinguish one predetermined region from another region, and therefore, the region should not be limited by such terms.

In the drawings, the thickness of a layer (film) or regions may be exaggerated for clarity. Also, if it is mentioned that a layer (film) is on or above another layer (film) or it can be formed directly on another layer (film) or substrate or between them a third layer (film) ) May be intervened.

The same reference numerals throughout the specification represent the same components.

FIG. 2 is a plan view schematically illustrating a general liquid crystal display, and FIG. 3 is a cross-sectional view taken along line II of FIG. 2 to schematically show a liquid crystal display according to the present invention.

2 and 3, a plurality of gate lines 126 and storage electrodes (not shown) are positioned on the substrate 110. The storage electrode may be a separate line independent from the gate line 126 or may be extended from the gate line 126. The first insulating layer 120 covers the gate line 126 and the storage electrode. The semiconductor layer 133 and the data line 136 are positioned on the first insulating layer 120. The semiconductor layer 133 may be the same as the amorphous silicon layer constituting the source and drain electrodes (not shown) of the thin film transistor T. The second insulating layer 130 covers the data line 136 and the semiconductor layer 133.

The gate line 126 and the data line 136 intersect horizontally and vertically. An area divided by the intersection of the gate line 126 and the data line 136 corresponds to a pixel area, and each pixel area includes a thin film transistor T and a pixel electrode 140.

The alignment layer 150 covers the substrate 110. The alignment layer 150 used in the liquid crystal display device may form a uniform thin film of less than or equal to 1000 mW at 200 ° C. or less and have excellent adhesion characteristics with the surface of the pixel electrode. In addition, the chemical stability is high and there should be no reaction with the liquid crystal. In addition, there should be no charge trap in electrical characteristics, and the resistivity should be high enough so as not to affect the operation of the liquid crystal molecules.

In the liquid crystal display according to the present invention, the semiconductor layer 133 extends to the side of the pixel electrode 140, so that the side surface of the pixel electrode 140 may be in contact with the second insulating layer 130 on the semiconductor layer 133. Therefore, the step difference caused by the semiconductor layer 133 and the data line 136 can be removed, so that rubbing R can be uniformly formed on the entire substrate. That is, a region (see FIG. 1) which does not rub in the prior art is not formed during the rubbing process after the alignment layer 150 is formed. Thereby, no abnormality in alignment of the liquid crystal molecules occurs.

4 is a cross-sectional view taken along the line II of FIG. 2 to schematically illustrate a liquid crystal display according to another exemplary embodiment of the present invention.

Referring to FIG. 4, unlike the above embodiment, the semiconductor layer 133 is extended to both sides of the data line 136. Although only one side of the pixel electrode 140 is in contact with the second insulating layer 130, both sides may be in contact with the second insulating layer 130.

5A through 5C are cross-sectional views taken along line II of FIG. 2 to explain a method of manufacturing a liquid crystal display device according to the present invention.

Referring to FIG. 5A, a first insulating layer 120 is formed on the substrate 110. In general, the substrate 110 is formed of glass, and the first insulating layer 120 is formed of a nitride film. Before the first insulating layer 120 is formed, a gate electrode (not shown) and a storage electrode (not shown) may be formed. The semiconductor layer 133 and the data line 136 are formed on the first insulating layer 120. In the liquid crystal display according to the exemplary embodiment, the semiconductor layer 133 extends to one side of the data line 136, but may extend to both sides. The semiconductor layer 133 may be formed when the active layer and the ohmic contact layer constituting the source and drain electrodes of the thin film transistor (not shown) are formed.

Referring to FIG. 5B, a second insulating layer 130 covering the substrate 110 is formed. The pixel electrode 140 is formed on the second insulating layer 130. In general, the second insulating layer 130 is formed of a nitride film, and the pixel electrode 140 is formed of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). Since parasitic capacitance may be formed between the pixel electrode 140 and the data line 136, the pixel electrode 140 should be formed to be spaced apart from the data line 136 by a predetermined distance.

Referring to FIG. 5C, an alignment layer 150 is formed on the substrate 110. In the liquid crystal display device using the twisted nematic (TN) mode, a polymer organic film printing method is generally used for forming the alignment layer 150. Inorganic alignment films typified by four-way deposition such as SiO ₂ may be used, but are not widely used in actual production due to problems such as process cost, reliability, and stability of operation.

Polyimide-based polymer compounds are widely used as the alignment layer 150 in consideration of orientation stability, durability, and productivity. As shown in FIG. 4C, since the alignment layer 150 is positioned on the surface of the pixel electrode 140 to apply the liquid crystal voltage, the thickness of the alignment layer 150 should be minimized to minimize the influence on the electrical operation characteristics of the liquid crystal molecules. Therefore, the thickness of the alignment layer 150 should be 1000 Å or less as the minimum thickness that can be uniformly applied. In order to print a uniform alignment film 150 or less in the form of a thin film of 1000 kPa or less, a low concentration mixed solution in which polyimide, an alignment film material, is diluted to about 4% to 5% is used.

Although the spin coating method may be used as the coating process of the alignment layer 150, the technique using a printing machine is mainly used because of the high consumption of solution and the additional process of removing the alignment layer around the active cell. do.

After the alignment layer 150 is formed, a rubbing process is performed. Rubbing (R) refers to rubbing the alignment layer 150 in a predetermined direction using a soft cloth. By rubbing (R) the polyimide alignment layer 150 in one direction using a fabric in which cotton or nylon fibers are implanted, liquid crystal molecules are arranged in a predetermined direction on the surface of the alignment layer 150. Therefore, the liquid crystal molecules may not be aligned in a certain direction unless the alignment layer 150 is properly rubbed.

In the liquid crystal display according to the present invention, the step caused by the semiconductor layer and the data line may be eliminated by extending the semiconductor layer 133 or making the side surface of the pixel electrode 140 contact the second insulating layer 130. have. As a result, rubbing R with respect to the alignment layer 150 may be uniformly performed on the entire substrate 110.

On the other hand, in the detailed description of the present invention has been described with respect to specific embodiments, various modifications are of course possible without departing from the scope of the invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be defined not only by the claims below but also by the equivalents of the claims of the present invention.

According to the present invention described above, since the rubbing of the alignment layer is uniformly performed on the entire substrate, disorientation of the liquid crystal molecules does not occur. Therefore, the image can be expressed uniformly as a whole.

In addition, the side light leakage can be reduced by the expansion of the semiconductor layer.

Claims (11)

A first insulating film positioned on the substrate; A plurality of data lines positioned on the first insulating layer; A semiconductor layer interposed between the first insulating film and the data line; A second insulating film covering an entire surface of the substrate on which the data line and the semiconductor layer are formed; A pixel electrode on the second insulating layer and disposed between the data lines; And Including an alignment layer covering the entire surface of the substrate, The width of the semiconductor layer is larger than the width of the data line. The method of claim 1, And the second insulating layer is in contact with a side surface of the pixel electrode. The method of claim 2, And the second insulating layer is in contact with both sides of the pixel electrode. The method of claim 1, And the semiconductor layer extends to side portions of the pixel electrode positioned at both sides of the data line. The method of claim 1, The substrate is divided into a first region and a second region by the data line, And the semiconductor layer extends to the side of the pixel electrode positioned in the first region. The method of claim 5, The alignment layer is rubbed in the direction of the first region in the second region. A first insulating film positioned on the substrate; A plurality of data lines positioned on the first insulating layer; A semiconductor layer interposed between the first insulating film and the data line; A second insulating film covering an entire surface of the substrate on which the data line and the semiconductor layer are formed; A pixel electrode on the second insulating layer and disposed between the data lines; And Including an alignment layer covering the entire surface of the substrate, The second insulating layer is in contact with the side of the pixel electrode. The method of claim 7, wherein The second insulating layer is in contact with both sides of the pixel electrode. The method of claim 7, wherein And the semiconductor layer extends to side portions of the pixel electrode positioned at both sides of the data line. The method of claim 7, wherein The substrate is divided into a first region and a second region by the data line, And the semiconductor layer extends to the side of the pixel electrode positioned in the first region. The method of claim 7, wherein The alignment layer is rubbed in the direction of the first region in the second region.

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