KR20050123418A - Liquid crystal display - Google Patents

Abstract

The liquid crystal display according to the present invention includes a first substrate, a pixel electrode formed on the first substrate, a second substrate positioned above the pixel electrode at predetermined intervals, a black matrix formed on the second substrate, and a black matrix. Of the red, green, and blue filters formed on the second substrate and overlapping a portion, the overcoat film covering the black matrix and the color filter, the common electrode formed on the overcoat film, the blue filter, the green filter, and the red filter. It is preferable to include a liquid crystal layer formed between the pixel electrode and the common electrode and the first and second column spacers respectively formed on the common electrode corresponding to the color filter having the highest height and the color filter having the lowest height. . Accordingly, in the liquid crystal display according to the present invention, the first and second column spacers are formed on the color filters having a large height difference, respectively, so that the difference between the heights of the first and second column spacers is prevented, thereby preventing occurrence of liquid crystal injection defects and smear defects. do.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

The present invention relates to a liquid crystal display device.

The liquid crystal display is one of the most widely used flat panel display devices. The liquid crystal display includes two display panels on which a field generating electrode is formed and a liquid crystal layer interposed therebetween. It is a display device which controls the transmittance | permeability of the light which passes through a liquid crystal layer by rearranging.

The upper and lower substrates of the liquid crystal display are formed around the edges and are bonded by a sealing material confining the liquid crystal material, and are supported by spacers dispersed between the upper and lower substrates.

Spacers are classified into spherical and irregularly distributed beads spacers and column spacers or rigid spacers formed in a predetermined pattern.

The column spacer is formed by coating a photoresist film on a color filter display panel and exposing and developing the pattern to correspond to a portion of the pixel that does not transmit, for example, a channel portion, a gate line, a storage electrode line, and the like.

In this case, when the heights of the column spacers respectively formed inside the red, green, and blue filters corresponding to the storage electrode lines are constant, the column spacers of the predetermined portion may be broken when external pressure is applied to the upper and lower substrates of the liquid crystal display. It is easy to collapse, and the external membrane under the column spacer of a predetermined part is easily broken and collapsed by external pressure. As such, when the column spacer and the lower layer are broken and collapsed, smears, that is, black spots occur. That is, the design margin for preventing the occurrence of smear defects is small.

In addition, when the heights of the column spacers are constant, the margin of liquid crystal injection is small, so that a region where liquid crystal is not injected when liquid crystal is injected or a region where an excessive amount of liquid crystal is injected easily occurs.

An object of the present invention is to provide a liquid crystal display device that maximizes the margin of liquid crystal injection and smear defects by providing a difference between heights of column spacers on each color filter.

The liquid crystal display according to the present invention includes a first substrate, a pixel electrode formed on the first substrate, a second substrate positioned above the pixel electrode at a predetermined interval, a black matrix formed on the second substrate, A red, green and blue filter overlapping a portion of the black matrix and formed on the second substrate, an overcoat layer covering the black matrix and the color filter, a common electrode formed on the overcoat layer, and the blue filter First and second column spacers respectively formed on the common electrode corresponding to the color filter having the highest height and the color filter having the lowest height among the green filter and the red filter, and between the pixel electrode and the common electrode. It is preferable to include a liquid crystal layer.

In addition, the first and second column spacers are formed at positions corresponding to the storage electrode lines, and the height difference between the color filter having the highest height and the color filter having the lowest height among the blue filter, the green filter, and the red filter is It is preferable that it is 3000 GPa or more.

Further, it is preferable that the color filter having the highest height is the blue filter, and the color filter having the lowest height is the red filter.

Then, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A liquid crystal display according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a layout view of a thin film transistor array panel for a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2A is a cross-sectional view of the thin film transistor array panel of FIG. 1 taken along a line IIa-IIa ′, and FIG. Is a cross-sectional view of the thin film transistor array panel taken along the line IIb-IIb ', and is a cross-sectional view of the liquid crystal display device in which the color filter display panel is coupled.

First, a thin film transistor array panel for a liquid crystal display will be described in detail with reference to the drawings.

1 to 2B, a plurality of gate lines 121 and a plurality of storage electrode lines 131 are formed on the insulating substrate 110.

The gate line 121 and the storage electrode line 131 mainly extend in the horizontal direction and are separated from each other. The gate line 121 transmits a gate signal, and a portion of each gate line 121 protrudes up or down to form a plurality of gate electrodes 124. The storage electrode line 131 receives a predetermined voltage such as a common voltage, and includes the storage electrode 137 formed by an extension extending upward or downward.

The gate line 121 and the storage electrode line 131 include a conductive film formed of a silver-based metal such as silver (Ag) or a silver alloy having a low resistivity, or an aluminum-based metal such as aluminum (Al) or an aluminum alloy. In addition to conductive films, chromium (Cr), titanium (Ti), tantalum (Ta), molybdenum (Mo) and alloys thereof with good physical, chemical and electrical contact properties with other materials, in particular ITO or IZO [see: Molybdenum-Tungsten (MoW) alloy] may have a multilayer film structure including another conductive film. An example of the combination of the lower layer and the upper layer is chromium / aluminum-neodymium (Nd) alloy.

Sides of the gate line 121 and the storage electrode line 131 are inclined, and the inclination angle is in a range of about 30-80 ° with respect to the surface of the substrate 110.

A gate insulating layer 140 made of silicon nitride (SiNx) is formed on the gate line 121 and the storage electrode line 131.

A plurality of linear semiconductors 151 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated a-Si) and the like are formed on the gate insulating layer 140. The linear semiconductor 151 extends mainly in the longitudinal direction, from which a plurality of extensions 154 extend toward the gate electrode 124.

A plurality of linear and island ohmic contacts 161 and 165 made of a material such as n + hydrogenated amorphous silicon doped with silicide or n-type impurities at a high concentration are formed on the semiconductor 151. have. The linear contact member 161 has a plurality of protrusions 163, and the protrusions 163 and the island contact members 165 are paired and positioned on the protrusions 154 of the semiconductor 151.

Side surfaces of the semiconductor 151 and the ohmic contacts 161 and 165 are also inclined, and the inclination angle is 30 to 80 degrees.

A plurality of data lines 171 and a plurality of drain electrodes 175 are formed on the ohmic contacts 161 and 165 and the gate insulating layer 140, respectively.

The data line 171 mainly extends in the vertical direction to cross the gate line 121 and transmit a data voltage. A plurality of branches extending from the data line 171 toward the drain electrode 175 forms a source electrode 173. The pair of source electrode 173 and the drain electrode 175 are separated from each other and positioned opposite to the gate electrode 123. The drain electrode 175 extends toward the extension portion 137 of the storage electrode line 131 and has an extension portion 177 overlapping the extension portion 137. The gate electrode 123, the source electrode 173, and the drain electrode 175 form a thin film transistor (TFT) together with the exposed portion 154 of the semiconductor 151, and a channel of the thin film transistor It is formed in the exposed portion 154 between the source electrode 173 and the drain electrode 175.

The data line 171 and the drain electrode 175 may also include a conductive film made of a silver metal or an aluminum metal. In addition to the conductive film, chromium (Cr), titanium (Ti), tantalum (Ta), and molybdenum (Mo) may be used. ) And other conductive films made of alloys thereof. Sides of the data line 171 and the drain electrode 175 are also inclined, and the inclination angle is in the range of about 30-80 ° with respect to the horizontal plane.

A passivation layer 180 made of an organic insulating material is formed on the data line 171, the drain electrode 175, and the exposed semiconductor portion 154. The passivation layer 180 has a contact hole 182 exposing a part 179 of the data line 171 and a contact hole 186 exposing a part of the drain electrode 175.

A plurality of pixel electrodes 190 and a plurality of contact assistants 82 made of ITO or IZO are formed on the passivation layer 180.

The pixel electrode 190 is physically and electrically connected to the drain electrode 175 through the contact hole 186 to receive a data voltage from the drain electrode 175.

The pixel electrode 190 to which the data voltage is applied rearranges the liquid crystal molecules of the liquid crystal layer between the two electrodes by generating an electric field together with a common electrode (not shown) of the upper panel.

In addition, the pixel electrode 190 and the common electrode form a capacitor (hereinafter referred to as a liquid crystal capacitor) to maintain an applied voltage even after the thin film transistor is turned off. There are other capacitors connected in parallel, called storage electrodes. The storage capacitor is made of the overlap of the pixel electrode 190 and the storage electrode line 131 and the overlap of the pixel electrode 190 and the neighboring gate line 121 (which is referred to as a prior gate line). In order to increase the capacitance of the capacitor, that is, the storage capacitor, an expansion unit 137 extending the storage electrode line 131 is provided to increase the overlap area, while drain connected to the pixel electrode 190 and overlapping the expansion unit 137. An extension 177 of the electrode 175 is placed under the passivation layer 180 to close the distance between the two.

The contact auxiliary member 82 is connected to the end portion 179 of the data line 171 through the contact hole 182. The contact assisting member 82 is not essential to serve to protect adhesiveness between the end portion 179 of the data line 171 and an external device and to protect them, and application thereof is optional.

One end portion 129 of the gate line 121 is used to receive a signal transmitted from a gate driving circuit (not shown) and may have a width wider than the width of the gate line 121.

The passivation layer 180 has a plurality of contact holes 181 exposing the end portion 129 of the gate line 121, and the contact hole 181 contacts the end portion 129 of the gate line 121. A plurality of contact auxiliary members 81 are formed. The contact auxiliary member 81 and the contact hole 181 may include a display panel 100 or a flexible circuit board (not shown) in the form of a chip in which a gate driving circuit (not shown) that supplies a signal to the gate line 121 is provided. Required if mounted on On the other hand, when the gate driving circuit is made of a thin film transistor or the like directly on the substrate 110, the contact hole 181 and the contact auxiliary member 81 are not required.

The lower alignment layer 11 that determines the alignment of the liquid crystal is formed on the pixel electrode 190.

As shown in FIG. 2B, the upper substrate 210 is positioned above the lower alignment layer 11 at a predetermined interval. A black matrix 220 is formed on the upper substrate 210 to form a matrix to separate pixel regions.

A red filter 230R, a green filter 230G, and a blue filter 230B, which are required to display an image between the black matrix 220 and overlap with a portion of the black matrix 220, are formed.

In FIG. 2B, the blue filter 230B, the green filter 230G, and the red filter 230R are formed such that the height of the color filter gradually decreases in the order of the blue filter 230B, the green filter 230G, and the red filter 230R. Although the case is illustrated, the height difference between the red filter 230R, the green filter 230G, and the blue filter 230B may be changed according to the type or thickness of the photoresist film for forming the process and the color filter.

In one embodiment of the present invention, the blue filter 230B, the green filter 230G, and the red filter 230R have the heights of the color filters in the order of the blue filter 230B, the green filter 230G, and the red filter 230R. The case where it is formed so that it will become small gradually is demonstrated. That is, the height of the blue filter 230B is the largest, the height of the green filter 230G is the largest, and the height of the red filter 230R is the smallest.

Black matrix 220, blue filter 230B, green filter 230G and red filter 230R to protect black matrix 220, blue filter 230B, green filter 230G and red filter 230R The overcoat film 250 is formed on it.

The common electrode 270 that forms an electric field together with the pixel electrode 190 is formed on the overcoat layer 250.

First and second column spacers 320B and 320R are formed on the common electrode 270. As shown in FIG. 2B, the first and second column spacers 320B and 320R are formed on the common electrode 270 corresponding to the blue filter 230B and the red filter 230R of the upper substrate 210, respectively. have.

That is, the first and second column spacers respectively correspond to the blue filter 230B having the highest height and the red filter 230R having the lowest height among the blue filter 230B, the green filter 230G, and the red filter 230R. 320B and 320R are formed on the common electrode 270.

As shown in FIG. 1, the first and second column spacers 320B and 320R are formed at positions corresponding to the storage electrode lines 131 and 137 of the lower substrate 110.

The columnar first and second column spacers 320B and 320R support the two substrates 110 and 210 in parallel to maintain a constant gap (cell gap) of the liquid crystal layer 3.

The upper alignment layer 21 is formed under the common electrode 270.

In this case, in the related art, the blue filter 230B and the red filter 230R are formed such that the height difference between the blue filter 230B and the red filter 230R is about 2000 dB, but in one embodiment of the present invention, the blue filter 230B ) And the blue filter 230B and the red filter 230R are formed on the upper substrate 210 so that the thickness difference d2 between the? And the red filter 230R is 3000 Å or more. That is, the height difference d2 between the blue filter 230B and the red filter 230R is increased to increase the height difference d2 of the base itself on which the first and second column spacers 320B and 320R are located. do.

In addition, the first and second column spacers formed at positions corresponding to the storage electrode line 131 and the color filter are conventionally formed on the blue filter 230B and the green filter 230G adjacent to each other. In the example, it is formed on the blue filter 230B and the red filter 230R.

Therefore, the height difference d1 between the first column spacer 320B formed on the highest blue filter 230B and the second column spacer 320R formed on the lowest red filter 230R becomes larger.

That is, the first and second column spacers 320B are formed by forming the first and second column spacers 320B and 320R, respectively, on the base having the height difference d2 already formed, that is, the blue filter 230B and the red filter 230R. , So that the height difference d1 between 320R is greater.

As such, the height difference d1 between the first and second column spacers 320B and 320R is large so that a column spacer and a column that are likely to occur when an external pressure acts on the upper and lower substrates 110 and 210 of the liquid crystal display device. The occurrence of smear defects or black gaps due to breakage and collapse of the lower layer under the spacer can be prevented. That is, by increasing the height difference d1 between the first and second column spacers 320B and 320R, a design margin for preventing occurrence of smear defects can be secured.

In addition, by increasing the height difference d1 between the first and second column spacers 320B and 320R, the margin of the liquid crystal injection is large, so that an area where liquid crystal is not injected or an excessive amount of liquid crystal is injected. It can be prevented from occurring.

Bubble or line defects caused by insufficient liquid crystal amount based on the amount of liquid crystal injected to form a target cell gap are called AUA (Active Unfilled Area) defects. The defect caused by the excessive input is called a border defect. By making the height difference between the first and second column spacers large, it is possible to prevent the occurrence of such an Active Unfilled Area (AUA) defect or an edge defect.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

In the liquid crystal display according to the present invention, the first and second column spacers are formed on the color filters having a large height difference, respectively, so that the difference between the heights of the first and second column spacers is prevented.

1 is a layout view of a thin film transistor array panel for a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2A is a cross-sectional view of the thin film transistor array panel of FIG. 1 taken along a line IIa-IIa ',

FIG. 2B is a cross-sectional view of the thin film transistor array panel of FIG. 1 taken along the line IIb-IIb ', and is a cross-sectional view of the liquid crystal display with the color filter display panel coupled thereto.

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

110: substrate 121, 129: gate line

124: gate electrode 140: gate insulating film

151 and 154 semiconductor 161 and 165 resistive contact members

171, 179: data line 173: source electrode

175: drain electrode 180: protective film

181, 182, 185: contact hole 190: pixel electrode

81, 82: contact auxiliary member

Claims (4)

First substrate, A pixel electrode formed on the first substrate, A second substrate spaced apart from the pixel electrode at a predetermined interval; A black matrix formed on the second substrate, Blue, green, and red filters overlapping a portion of the black matrix and formed on the second substrate, An overcoat film covering the black matrix and the color filter, A common electrode formed on the overcoat film, First and second column spacers respectively formed on the common electrode in response to the color filter having the highest height and the color filter having the lowest height among the blue filter, the green filter, and the red filter; Liquid crystal layer formed between the pixel electrode and the common electrode Liquid crystal display comprising a. In claim 1, The first and second column spacers are formed at positions corresponding to the storage electrode lines. In claim 1, And a difference in height between a color filter having the highest height and a color filter having the lowest height among the blue filter, the green filter, and the red filter is 3000 Å or more. The method according to any one of claims 1 to 3, And the color filter having the highest height is the blue filter, and the color filter having the lowest height is the red filter.