KR101320047B1 - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal display device, wherein the liquid crystal display device according to the present invention includes a first substrate, a second substrate facing the first substrate, and a liquid crystal layer positioned between both substrates, wherein the first substrate is insulated from each other. A gate line and a data line; A switching element operable in response to a signal applied to the gate line and the data line; And a pixel electrode electrically connected to the switching element, wherein the second substrate includes a common electrode, and the common electrode connects a portion facing the pixel electrode and a portion facing the pixel electrode, and includes at least one of a gate line and a data line. It is characterized in that it partially overlaps with any one. As a result, a liquid crystal display device having improved aperture ratio by reducing light leakage caused by an interference electric field is provided.

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

1 is a layout view of a liquid crystal display according to a first embodiment of the present invention;

2 is a layout view in which only the first substrate of the liquid crystal display according to the first embodiment is separated;

3 is a layout view illustrating a common electrode, a gate line, and a data line of the liquid crystal display according to the first embodiment;

4 is a cross-sectional view taken along II-II of FIG. 1,

5 is a cross-sectional view taken along line III-III of FIG. 1,

6 is a cross-sectional view taken along line IV-IV of FIG. 1,

7a and 7b are cross-sectional views for explaining the effect of the present invention,

8 is a layout view of a liquid crystal display according to a second exemplary embodiment of the present invention.

9 is a layout view showing another embodiment of the second embodiment.

Explanation of symbols on the main parts of the drawings

121: gate line 141: data line

142: source electrode 143: drain electrode

161: pixel electrode 162: pixel electrode incision pattern

251: common electrode 252: common electrode incision pattern

251a: first part 251b: second part

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having an improved aperture ratio.

In the liquid crystal display, the transmittance of light of a liquid crystal, which is an intermediate state material between a liquid and a crystal, changes according to an applied voltage. By using this characteristic, the input electrical signal is converted into visual information to transmit an image. The transmittance of the liquid crystal to the light depends on the arrangement of the liquid crystal, and the arrangement of the liquid crystal depends on the electric field applied to the liquid crystal. The liquid crystal molecules have different physical properties in the long axis direction and the short axis direction. As a result, when the electric field is applied, the electric forces acting in the long axis direction and the short axis direction of the liquid crystal molecules are different. Different.

In general, the LCD includes a first substrate on which gate lines, data lines, thin film transistors, pixel electrodes, and the like are formed, a second substrate on which common electrodes are formed, and a liquid crystal layer positioned between both substrates.

A voltage is applied to the pixel electrode by using the gate line and the data line, and there is a problem in that light leakage occurs due to an interference electric field around the gate line or the data line.

In order to prevent such light leakage, the black matrix is installed, but there is a problem that the aperture ratio is lowered due to the black matrix.

Accordingly, an object of the present invention is to provide a liquid crystal display device having an improved aperture ratio.

The object is achieved by a liquid crystal display device comprising a first substrate, a second substrate facing the first substrate, and a liquid crystal layer positioned between the both substrates, wherein the first substrate comprises a gate line that insulates and crosses each other; And a pixel electrode electrically connected to the switching element, the switching element operating in response to a signal applied to the data line, the gate line, and the data line, wherein the second substrate includes a common electrode, and the common electrode And a second portion connecting the first portion corresponding to the pixel electrode and the first portion to each other and partially overlapping at least one of the gate line and the data line.

An incision pattern is formed in the pixel electrode and the common electrode to form a domain dividing means, thereby improving the viewing angle.

The domain dividing means may be formed as a projection instead of a cutting pattern.

When the liquid crystal layer is in the vertical alignment mode, the liquid crystal layers are aligned in the vertical direction, and light transmittance is controlled to the extent that the liquid crystal molecules lie down when voltage is applied to the pixel electrode. When a voltage is applied to the pixel electrode and the domain is divided into a cutting pattern or a projection between the pixel electrode and the common electrode, the liquid crystal molecules lie in various directions, thereby improving the viewing angle.

The pixel electrode may be formed in a bent shape one or more times, and the data line may be bent along the edge shape of the pixel electrode. In this case, the length of the data line becomes long, and a signal delay may occur. In order to solve this problem, the signal transmission can be balanced by increasing the number of overlapping portions with the gate lines rather than overlapping portions with the data lines.

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

In the following expressions, a film is formed "top" of another film, not only when two films are in contact with each other but also when another film is present between the two films. It also includes the case.

1 is a layout view of a liquid crystal display according to a first exemplary embodiment of the present invention. 2 is a layout view in which only a first substrate of the liquid crystal display according to the first embodiment is separated, and FIG. 3 is a layout view showing a common electrode, a gate line, and a data line of the liquid crystal display according to the first embodiment.

The upper second substrate 200 (see FIG. 4) has a common electrode 251, and the first substrate 100 is disposed in parallel to the second substrate 200. An opaque gate line 121 and a data line 141 are formed on the first substrate 100 (see FIG. 4) in left and right directions and in a vertical direction, and thin film transistors T (see FIG. 4) are formed at each crossing point. have. The thin film transistor T includes a gate electrode 122, a source electrode 142, and a drain electrode 143.

In the pixel electrode 161 connected to the drain electrode 143 of the thin film transistor T, an elongated cutout pattern 162 is formed in a diagonal direction to lie the liquid crystal molecules in different directions when voltage is applied. In addition, a cutting pattern 252 is formed on the common electrode 251 of the second substrate 200. The cutting pattern 162 of the pixel electrode and the cutting pattern 252 of the common electrode are alternately arranged.

The common electrode 251 includes a first portion 251a and a second portion 251b. The first portion is a portion corresponding to the pixel electrode 161, and the second portion 251b is a portion corresponding to the gate line 121 or the data line 141. The second portion 251b is configured to connect the first portions 251a to each other.

4 is a cross-sectional view of the liquid crystal display according to the first embodiment of the present invention.

Referring to this, the first substrate 100 and the second substrate 200 will be described in detail as follows.

First, the first substrate 100 will be described in detail as follows.

As the first insulating substrate 111, an insulating substrate such as transparent glass or plastic may be used.

Gate wiring is formed on the first insulating substrate 111. The gate wiring can be a metal single layer or multiple layers. The gate wiring includes a gate line 121 extending in the transverse direction and a gate electrode 122 connected to the gate line 121. Although not shown, the gate line may include a storage electrode line extending in parallel with the gate line 121 and passing through the center of the pixel.

The gate line 121 and the gate electrode 122 are formed by depositing a metal film by a sputtering method using chromium or aluminum, and then patterning the metal film. The gate line 121 extends in one direction as in the row direction, and the gate electrode 122 is branched from the gate line 121.

The gate insulating layer 131 made of silicon nitride or the like covers the gate wiring on the first insulating substrate 111. The gate insulating layer 131 may be formed of a silicon nitride film using a plasma chemical vapor deposition method, and insulates the gate line 121 from the gate electrode 122.

A semiconductor layer 132 made of a semiconductor such as amorphous silicon is formed on the gate insulating layer 131 of the gate electrode 122, and an n + hydrogenated amorphous layer in which the n-type impurity is heavily doped is formed on the semiconductor layer 132. A resistance connecting layer 133 made of a material such as silicon is formed.

An ohmic contact layer 133 is formed in the channel portion between the source electrode 142 and the drain electrode 143.

Data wirings are formed on the ohmic contact layer 133 and the gate insulating film 131. The data lines may also be a single layer or multiple layers of metal layers. The data line is a branch of the data line 141 and the data line 141 which are formed in the vertical direction and intersect the gate line 121 to form a pixel, and extends to the upper portion of the resistance contact layer 133. And a drain electrode 143 which is separated from the source electrode 142 and is formed on the resistive contact layer 133 opposite to the source electrode 142.

The source electrode 142 is formed by extending one side of the data line 141, and the drain electrode 143 is spaced apart from the source electrode 142 to face each other. The upper portion of the semiconductor layer 132 made of n + amorphous silicon is separated from each other by patterning using the source electrode 142 and the drain electrode 143 as an etching mask.

The upper portion of the data line and the semiconductor layer 132 not covered by the semiconductor layer is made of silicon nitride and the like, and a protective film 151 for protecting the thin film transistor T and the like is formed.

An organic film 152 is formed on the protective film 151. The organic layer 152 is thicker than the gate insulating layer 131 and the passivation layer 151, and may be formed by spin coating, slit coating, screen printing, or the like.

The organic layer 152 may be any one of a benzocyclobutene (BCB) series, an acrylic resin series, a polyimide series, and a fluorine resin series.

In the organic layer 152, a contact hole 171 exposing the drain electrode 143 is formed. The protective film 151 is also removed from the contact hole 171. The pixel electrode 161 and the drain electrode 143 are connected by the contact hole 171.

The pixel electrode 161 is formed by depositing a thin film of indium zinc oxide, indium tin oxide, or the like and patterning the thin film. In the patterning step, the cutout pattern 162 of the pixel electrode 161 is formed.

Next, the second substrate 200 will be described in detail.

The black matrix 221 is formed on the second insulating substrate 211. The black matrix 221 is usually made of a photosensitive organic material to which a black pigment is added. As the black pigment, carbon black, titanium oxide, or the like is used.

The color filter 231 is formed on the second insulating substrate 211 and the black matrix 221, and the color filter 231 may include sublayers of different colors. The color filter 231 may not be formed with the same thickness but may be formed with a different thickness according to the color.

An overcoat film 241 is formed on the color filter 231. The overcoat layer 241 may be formed by spin coating using an acrylic resin or the like. The overcoat layer 241 may protect the color filter 231 and, when the thickness difference of the color filter 231 is large, is formed on the upper portion of the second substrate 200. It serves to planarize the curved surface. The overcoat film 241 may be omitted.

The common electrode 251 is formed on the overcoat layer 241, and the common electrode 251 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The common electrode 251 directly applies a voltage to the liquid crystal layer 300 together with the pixel electrode 161 of the first substrate 100.

A common electrode cutout pattern 252 is formed in the common electrode 251.

5 to 7B illustrate the effects of the present invention by simply showing the first and second substrates described above.

Specifically, FIG. 5 is a cross-sectional view of III-III of FIG. 1, and FIG. 6 is a cross-sectional view of IV-IV of FIG. 1. 7A and 7B are cross-sectional views for illustrating the effect of the invention compared to FIGS. 5 and 6.

FIG. 7A is a sectional view of the same part as FIG. 5, and FIG. 7B is a sectional view of the same part as FIG. 6. 7A and 7B are in contrast with FIGS. 5 and 6, which are cross-sectional views when the gate line 121 or the data line 141 and the common electrode 251 do not overlap with the second portion 251b minimized. A cross-sectional view of the entirety of the line 121 or the data line 141 and the common electrode 251 is illustrated.

5 to 7B are all for showing the darkness, and the same voltage as that of the common electrode 251 is applied to the pixel electrode 161. In order for liquid crystal molecules having negative dielectric anisotropy to express darkness without light leakage, the liquid crystal molecules (shown in the form of columns in the figure) must be vertically aligned without lying down.

First, FIGS. 7A and 7B will be described.

Referring to FIG. 7A, most of the liquid crystal molecules are arranged in the vertical direction, but the liquid crystal molecules of the portion adjacent to the gate line 121 are slightly inclined. An electric field in a vertical direction and a horizontal direction is formed between the common electrode 251 and the gate line 121. The long axis of the liquid crystal molecules is inclined by the electric field. Light leakage occurs due to the inclination of the long axis, and d3, a section in which the long axis is tilted in FIG. 7A, is wider than d1, a section in which the long axis is tilted in FIG. 5.

FIG. 7B is similar to FIG. 7A when the portion overlapping the common electrode 251 is the data line 141.

5 and 6, the overlapping portion of the common electrode 251 and the data line 141 or the gate line 121 in FIGS. 7A and 7B is removed.

For example, the cross-sectional view of the cross-sectional view of the gate electrode 121 and the data line 141 may be omitted. 2 parts 251b remain.

By not overlapping the gate line 121, the data line 141, and the common electrode 251, generation of a vertical electric field may be prevented, and liquid crystal molecules may maintain a vertical arrangement state, thereby preventing light leakage. Since there is no light leakage, it is not necessary to provide the black mattress 221, and as a result, the aperture ratio can be improved.

In addition, according to the present invention, the overlapping portion of the gate line 121 and the common electrode 251 may be reduced to reduce the gate signal delay. This is because when the gate line 121 and the common electrode 251 overlap, electrical interference occurs, thereby delaying the gate signal transmission.

Of course, the data signal delay is also reduced. It is particularly desirable when the display device is large.

In terms of the manufacturing process, no further processing is required. In order to implement the present invention, the common electrode 251 is divided into a first part 251a and a second part 251b and patterned, since the common electrode 251 may be simultaneously patterned when the common electrode incision pattern 252 is patterned.

8 and 9 are planar structural diagrams of a liquid crystal display according to a second exemplary embodiment of the present invention. The basic structure is the same as in the first embodiment, but three bends are formed in the pixel electrode of the first substrate, and a cutout pattern 252 is formed in the common electrode of the second substrate. The data line 141 is bent along the edge shape of the pixel electrode 161.

Since the data line 141 is bent along the edge shape of the pixel electrode 161, the data line 141 may be lengthened, thus causing signal delay.

According to the second exemplary embodiment, a portion of the second portion where the data line 141 overlaps is smaller than a portion overlapping the gate line 121. As a result, the signal delay of the data line 141 may be minimized, and the neighboring first portions 251a may be electrically connected to each other.

In another embodiment, the common electrode may be provided so as not to overlap the data line 141.

In another embodiment, the incision pattern acting as the domain dividing means may replace its function by protrusion. Generally, the protrusions are formed by applying a photosensitive film on a substrate and then patterning the photoresist.

As described above, the present invention provides a liquid crystal display device having an improved aperture ratio by reducing signal delay and reducing light leakage.

Claims (7)

A liquid crystal display device comprising a first substrate, a second substrate facing the first substrate, and a liquid crystal layer positioned between the both substrates. The first substrate, A gate line and a data line insulated from each other and crossing each other; A switching element operable in response to a signal applied to the gate line and the data line; A pixel electrode electrically connected to the switching element, The second substrate includes a common electrode, The common electrode may include a second portion connecting the first portion corresponding to the pixel electrode and the first portion and partially overlapping at least one of the gate line and the data line. . The method of claim 1, The pixel electrode incision pattern is formed on the pixel electrode, And a domain dividing means is formed in the first portion. 3. The method of claim 2, And said domain dividing means of said first portion comprises a projection. 4. The method according to any one of claims 1 to 3, And the liquid crystal layer is in a vertical alignment mode. 4. The method according to any one of claims 1 to 3, And the pixel electrode is bent at least once in the extending direction of the data line. The method of claim 5, Wherein the data line is bent according to a shape of a rim of the pixel electrode. The method according to claim 6, And the second portion overlaps the gate line more than the data line.

Images