KR20040061447A - In-Plane Liquid Crystal Display Device and the Method for Manufacturing the same - Google Patents

Abstract

PURPOSE: An IPS(In-Plane Switching) mode LCD device is provided to form a transparent common electrode on an upper substrate by corresponding to a part where a pixel electrode of a lower substrate is formed, in order to form a vertical electric field, thereby preventing light leakage in a pixel electrode part. CONSTITUTION: A lower substrate(100) and an upper substrate(200) are comprised. An insulating film is formed on a front side of the lower substrate(100). The first common electrodes(130) are formed on the insulating film at certain intervals. A protective film(160) is formed on a front side of the lower substrate(100) including the first common electrodes(130). Pixel electrodes(150) are formed on the protective film(160) between the first common electrodes(130). The second common electrodes(230) are formed on the upper substrate(200) to be relative to the pixel electrodes(150). A liquid crystal layer is formed between the upper and lower substrates(200,100).

Description

In-plane liquid crystal display device and the method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a transverse electric field type liquid crystal display device having improved luminance by forming a common electrode corresponding to a lower pixel electrode on an upper plate, and a manufacturing method thereof.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELD), and vacuum fluorescent (VFD) Various flat panel display devices such as displays have been studied, and some of them are already used as display devices in various devices.

Among them, LCD is the most widely used as the substitute for CRT (Cathode Ray Tube) for mobile image display device because of its excellent image quality, light weight, thinness, and low power consumption. In addition to the use of the present invention has been developed in various ways such as a television and a computer monitor for receiving and displaying broadcast signals.

In order to use such a liquid crystal display as a general screen display device in various parts, it is a matter of how high quality images such as high definition, high brightness and large area can be realized while maintaining the characteristics of light weight, thinness and low power consumption. Can be.

A general liquid crystal display device may be largely divided into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel, wherein the liquid crystal panel includes first and second glass substrates bonded to each other with a predetermined space; It consists of a liquid crystal layer injected between the said 1st, 2nd glass substrate.

Here, the first glass substrate (TFT array substrate) has a plurality of gate lines arranged in one direction at regular intervals, a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines, A plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing a gate line and a data line, and a plurality of thin film transistors switched by signals of the gate line to transfer the signal of the data line to each pixel electrode. Is formed.

The second glass substrate (color filter substrate) includes a light shielding layer for blocking light in portions other than the pixel region, an R, G, and B color filter layers for expressing color colors, and a common electrode for implementing an image. Is formed.

The driving principle of the general liquid crystal display device uses the optical anisotropy and polarization property of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the arrangement of molecules can be controlled by artificially applying an electric field to the liquid crystal.

Therefore, when the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular arrangement direction of the liquid crystal by optical anisotropy, thereby representing image information.

Currently, an active matrix LCD, in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner, is attracting the most attention due to its excellent resolution and ability to implement video.

Hereinafter, a liquid crystal display according to the related art will be described with reference to the accompanying drawings.

1 is an exploded perspective view showing a typical twisted nematic liquid crystal display device.

As shown in FIG. 1, the lower substrate 1 and the upper substrate 2 are bonded to each other with a predetermined space, and a liquid crystal 3 injected between the lower substrate 1 and the upper substrate 2.

More specifically, the lower substrate 1 has a plurality of gate lines 4 arranged in one direction at regular intervals in order to define the pixel region P, and in a direction perpendicular to the gate line 4. A plurality of data lines 5 are arranged at regular intervals, and a pixel electrode 6 is formed in each pixel region P where the gate line 4 and the data line 5 intersect, and each gate line The thin film transistor T is formed at the portion where (4) and the data line 5 intersect.

The upper substrate 2 includes a light shielding layer 7 for blocking light in portions other than the pixel region P, R, G, and B color filter layers 8 for expressing color colors, and an image. A common electrode 9 is formed for implementation.

The thin film transistor T may include a gate electrode protruding from the gate line 4, a gate insulating film (not shown) formed on a front surface, an active layer formed on the gate insulating film above the gate electrode, and the data. And a source electrode protruding from the line 5 and a drain electrode to face the source electrode.

The pixel electrode 6 uses a transparent conductive metal having a relatively high light transmittance, such as indium-tin-oxide (ITO).

In the liquid crystal display device configured as described above, the liquid crystal 3 positioned on the pixel electrode 6 is aligned by a signal applied from the thin film transistor T, and the liquid crystal 3 is aligned according to the degree of alignment of the liquid crystal 3. (3) The image can be expressed by adjusting the amount of light passing through.

As described above, the liquid crystal panel drives the liquid crystal by an electric field applied up and down, and has excellent characteristics such as transmittance and aperture ratio, and the common electrode 9 of the upper substrate 2 serves as a ground to prevent static electricity. It is possible to prevent the destruction of the liquid crystal cell.

However, the liquid crystal drive by the electric field applied up-down has a disadvantage that the viewing angle characteristics are not excellent.

Accordingly, in order to overcome the above disadvantages, a new technology, that is, a liquid crystal display device having an in-plane switching mode, has been proposed.

Hereinafter, a conventional transverse electric field type liquid crystal display device will be described with reference to the accompanying drawings.

2 is a schematic cross-sectional view showing a general transverse electric field type liquid crystal display device.

As shown in FIG. 2, the pixel electrode 13 and the common electrode 15 are formed on the lower substrate 10 on the same plane. The liquid crystal 3 formed between the lower substrate 10 and the upper substrate 20 bonded to the lower substrate 10 may have a transverse electric field between the pixel electrode 13 and the common electrode 15 on the lower substrate 10. Works by

3A to 3B are views illustrating a change in orientation direction of liquid crystals occurring when voltage off / on in a transverse electric field type liquid crystal display.

That is, FIG. 3A shows an off state in which the transverse electric field is not applied to the pixel electrode 13 or the common electrode 15, so that the change in the alignment direction of the liquid crystal 3 does not occur. FIG. 3B is an on state in which a transverse electric field is applied to the pixel electrode 13 and the common electrode 15, and the orientation direction change of the liquid crystal 3 occurs, and is about 45 ° compared to the off state of FIG. 3A. It can be seen that with a twist angle, the horizontal direction of the pixel electrode 13 and the common electrode 15 coincides with the twist direction of the liquid crystal.

As described above, in the transverse electric field type liquid crystal display, both the pixel electrode 13 and the common electrode 15 exist on the same plane.

4A and 4B are plan views illustrating alignment directions of liquid crystals according to FIGS. 3A and 3B, respectively.

As shown in FIG. 4A, when no voltage is applied to the pixel electrode 13 or the common electrode 15, the liquid crystal alignment direction is arranged in the same direction as the rubbing angle of the alignment layer (not shown).

As shown in FIG. 4B, when a voltage is applied to the pixel electrode 13 and the common electrode 15, the alignment direction of the liquid crystal is a direction in which an electric field is applied.

The advantage of this transverse electric field method is that a wide viewing angle is possible. That is, when the liquid crystal display device is viewed from the front, the liquid crystal display device may be visible in the about 70 ° direction in the up / down / left / right directions. In addition, the manufacturing process is simpler than the liquid crystal display device used in general, and there is an advantage that the color shift according to the viewing angle is small.

However, the conventional transverse electric field type liquid crystal display device has a problem in that transmittance and aperture ratio due to light are reduced because the common electrode 15 and the pixel electrode 13 are present on the same substrate.

FIG. 5 is a plan view illustrating a conventional transverse electric field type liquid crystal display device, and FIGS. 6A and 6B are cross-sectional views illustrating liquid crystal alignment before and after voltage application on the line II ′ of FIG. 5.

5, 6A and 6B, the conventional transverse electric field type liquid crystal display device is largely a liquid crystal layer filled between the lower substrate 10, the upper substrate 20 opposite thereto, and the both substrates 10 and 20. consist of.

As illustrated in FIG. 5, a gate line 11 and a data line 12 are formed on the lower substrate 10 to cross each other in a vertical direction, and define a pixel region. The common electrode 15 and the pixel electrode ( 13) are formed at predetermined intervals.

The gate electrode 11a protruding from the gate line 11 and a gate insulating film (see 14 in FIGS. 6A and 6B) are formed on the entire surface of the lower substrate 10 including the gate electrode 11a. The semiconductor layer 18 overlapping the gate electrode 11a, the source electrode 12a protruding from the data line 12 on both sides of the semiconductor layer 18, and the drain electrode 12b spaced apart from the predetermined distance. A thin film transistor TFT is formed. The drain electrode 12b of the thin film transistor TFT is connected to the pixel electrode 15.

The common electrode 13 is formed to be spaced apart from the pixel electrode 15 by a predetermined interval, and simultaneously formed when the gate line 11 or the data line 12 is formed. In the figure shown, the common electrode 13 is formed on the same layer as the data line 12.

Further, a passivation layer 16 is further deposited between the data line 12 and the pixel electrode 15, wherein the passivation layer (see 16 in FIGS. 6A and 6B) has the same component as the gate insulating layer 14. An inorganic insulating film such as SiNx or SiOx, or an organic insulating film of acryl, polyimide, BCB (BenzoCycloButene), or photopolymer is used.

The first alignment layer 17 is formed on the entire lower substrate 10 including the passivation layer 16 and the pixel electrode 15.

In addition, the common electrode 13 receives a voltage signal from the common line 19, and when a voltage signal is applied to each pixel electrode 15 through the drain electrode 12b, the common electrode 13 forms a horizontal electric field to drive the liquid crystal. .

On the upper substrate 20, a light shielding layer 21 for blocking light leakage to an area other than the pixel region, a color filter layer 22 for implementing color colors R, G, and B, and a liquid crystal. A second alignment film 23 is defined to define the initial orientation of.

First and second alignment layers 17 and 23 defining an initial alignment of the liquid crystal are formed on the front surfaces of both substrates 10 and 20, and the liquid crystals adjacent to the first and second alignment layers 17 and 23 are aligned. It is arranged according to the orientation direction of.

As shown in FIG. 6A, the liquid crystal before voltage application is defined according to the rubbing directions of the first and second alignment layers 17 and 23 formed on the lower substrate 10 and the upper substrate 20, respectively. Therefore, as shown in the drawing, the shape of the liquid crystal in the direction perpendicular to the common electrode 13 and the pixel electrode 15 is in a form close to a circle.

In addition, as shown in FIG. 6A, the optical mode of the general transverse electric field type is applied, and transmission of light before voltage application is normally performed to normally black.

As shown in FIG. 6B, when a voltage is applied to the pixel electrode 15 and the common electrode 13, an electric field is formed between two electrodes 13 and 15 formed on the same substrate, and the two electrodes 13 and 15. The liquid crystal is aligned along the electric field formed between the layers.

At this time, as shown in the figure, since the shape of the liquid crystal in the vertical direction of the common electrode 13 and the pixel electrode 15 is located in the direction formed in the electric field, the shape of the liquid crystal is seen as a long oval.

After voltage is applied, internal light is transmitted along the liquid crystal to display a white state.

Here, since the liquid crystal corresponding to the portion where the pixel electrode 15 and the common electrode 13 are formed is located in a region where an electric field is divided, it is not easy to move in a specific direction when voltage is applied to each electrode. Therefore, when the display is performed, the pixel becomes a portion where foreground lines are formed, and light is not transmitted through the pixel electrode 15 and the formation region of the common electrode 13 so that the pixel electrode 15 and the common electrode ( 13) is formed of metal or deposited by alloy of ITO / metal to prevent light leakage phenomenon.

The conventional transverse electric field type liquid crystal display device has the following problems.

In a transverse electric field type liquid crystal display device which drives a liquid crystal by forming a horizontal electric field between a pixel electrode and a common electrode, a problem occurs in that a liquid crystal directly above each electrode is located in an area where an electric field is distinguished and thus does not move smoothly. There is a problem in that light leakage occurs in the vicinity of the pixel electrode and the common electrode after voltage is applied in the driving mode.

In order to prevent the light leakage, an alternative of forming the pixel electrode and the common electrode with an opaque metal has been proposed, but in this case, the aperture ratio is lost as much as the portion where the pixel electrode and the common electrode are formed.

An object of the present invention is to provide a transverse field type liquid crystal display device having improved luminance by forming a common electrode corresponding to a pixel electrode of a lower plate on the upper plate.

1 is an exploded perspective view showing a typical twisted nematic liquid crystal display device

2 is a schematic cross-sectional view showing electric field formation and thereby liquid crystal alignment in a general transverse electric field type liquid crystal display device.

3A to 3B are views illustrating alignment directions of liquid crystals at voltage off / on in a transverse electric field type liquid crystal display device;

4A and 4B are plan views showing alignment directions of liquid crystals according to FIGS. 3A and 3B, respectively.

5 is a plan view illustrating a conventional transverse electric field type liquid crystal display device.

6A and 6B are cross-sectional views illustrating a liquid crystal alignment before and after applying voltage on the line II ′ of FIG. 5.

7A and 7B are plan views of a lower substrate and an upper substrate showing a transverse electric field type liquid crystal display device of the present invention.

8A and 8B are cross-sectional views showing the alignment of the liquid crystals before and after applying voltage on the line II to II 'of the transverse electric field type liquid crystal display device of the present invention shown in FIGS. 7A and 7B.

* Description of symbols on the main parts of the drawings *

100: lower substrate 110: gate line

110a: gate electrode 120: data line

120a / 120b: source electrode / drain electrode 130: first common electrode

135: first common line 140: gate insulating film

150: pixel electrode 160: protective film

170: first alignment layer 180: semiconductor layer

200: upper substrate 210: light shielding layer

220: color filter layer 230: second common electrode

235: second common line 240: second alignment layer

The transverse field type liquid crystal display device of the present invention for achieving the above object is a lower substrate and the upper substrate, an insulating film formed on the front surface of the lower substrate, a plurality of first common electrodes formed at regular intervals on the insulating film And a passivation layer formed on an entire surface of the lower substrate including the first common electrode, a pixel electrode formed on the passivation layer between the first common electrode, and a second common electrode formed on the upper substrate so as to correspond to the pixel electrode. And a liquid crystal layer formed between the upper and lower substrates.

And first and second alignment layers formed on opposite surfaces of the upper and lower substrates, and polarizing plates vertically intersecting with each other on a rear surface of the upper and lower substrates and having a transmission axis of 45 ° with respect to the alignment direction of the alignment layers. desirable.

Preferably, the first and second common electrodes are different metals.

The first common electrode is preferably made of any one metal of Cu, Cr, Mo, Al, Ti, Ta, Al alloy.

Preferably, the pixel electrode and the second common electrode are the same metal.

The second common electrode is preferably any one of indium oxide, zinc oxide, indium-tin composite oxide film, tin-antimony composite oxide, zinc-aluminum composite oxide film, and indium-zinc composite oxide.

It is preferable that the same common voltage signal is applied to the first and second common electrodes.

The liquid crystal layer is preferably made of a liquid crystal having a positive dielectric anisotropy.

In addition, a method of forming a transverse electric field type liquid crystal display device according to the present invention for achieving the same object comprises the steps of preparing an upper and lower substrates, forming an insulating film on the entire surface of the lower substrate, a plurality of having a predetermined interval on the insulating film Forming a plurality of first common electrodes, forming a passivation layer on an entire surface of the lower substrate including the first common electrode, forming a pixel electrode on the passivation layer between the first common electrode, and forming the pixel electrode Forming a first alignment layer on a front surface of the lower substrate including the second substrate, forming a second common electrode on the upper substrate to correspond to the pixel electrode, and forming a first alignment layer on the front surface of the upper substrate including the second common electrode; Forming a second alignment layer, forming first and second polarizing plates on a rear surface of the upper and lower substrates, and forming a liquid crystal layer between the upper and lower substrates. Its characteristics include that of forming.

Preferably, the first and second polarizing plates have a polarization axis perpendicular to each other, and the transmission axes of the first and second polarizing plates are formed at 45 ° with respect to the alignment directions of the first and second alignment layers, respectively.

Preferably, the first and second common electrodes are different metals.

The first common electrode is preferably made of any one metal of Cu, Cr, Mo, Al, Ti, Ta, Al alloy.

Preferably, the pixel electrode and the second common electrode are the same metal.

The second common electrode is preferably any one of indium oxide, zinc oxide, indium-tin composite oxide film, tin-antimony composite oxide, zinc-aluminum composite oxide film, and indium-zinc composite oxide.

It is preferable that the same common voltage signal is applied to the first and second common electrodes.

The liquid crystal layer is preferably made of a liquid crystal having a positive dielectric anisotropy.

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

7A and 7B are plan views of a lower substrate and an upper substrate showing a transverse electric field type liquid crystal display device according to the present invention, and FIGS. 8A and 8B are cross-sectional views showing liquid crystal alignment before and after applying voltage on the line II-II 'of FIG. 7. .

As shown in FIGS. 7A and 7B, the transverse electric field type liquid crystal display device of the present invention is largely a liquid crystal layer filled between the lower substrate 100, the upper substrate 200 opposite thereto, and the two substrates 100 and 200 ( 8a and 300b of FIG. 8b).

As shown in FIG. 7A, a gate line 110 and a data line 120 are formed on the lower substrate 100 to cross each other in a vertical direction to define a pixel area, and a first common electrode 130 and a pixel are formed in the pixel area. The electrodes 150 are formed at predetermined intervals.

When the voltage signal is applied to each pixel electrode 150 through the drain electrode 120b, the first common electrode 130 receives a voltage signal from the first common line 135 formed over all the pixels. Is formed to drive the liquid crystal.

The gate electrode 110a protruding from the gate line 110 and the gate insulating layer (see 140 of FIGS. 8A and 8B) are disposed on the entire surface of the lower substrate 100 including the gate electrode 110a. The semiconductor layer 180 overlapping the gate electrode 110a, the source electrode 120a protruding from the data line 120 on both sides of the semiconductor layer 180, and the drain electrode 120b spaced apart from the predetermined distance. Is done.

The gate electrode 110a, the gate insulating layer 140, the semiconductor layer 180, the source electrode 120a, and the drain electrode 120b form a thin film transistor TFT.

The drain electrode 120b of the thin film transistor TFT is connected to the pixel electrode 150.

As shown in FIG. 7B, on the upper substrate 200, a light shielding layer 210 formed to correspond to a portion except the pixel region and color colors R, G, and the like to block light leakage to an area other than the pixel region. A second common electrode 230 is formed on a color filter layer (see 220 of FIGS. 8A and 8B) for implementing B) and a portion corresponding to the pixel electrode 150 formed on the lower substrate 100.

In addition, in the second common electrode 230 formed on the upper substrate 200, a second common line 235 is formed across all pixels to receive the same voltage to apply voltage.

Hereinafter, a method of manufacturing the transverse electric field type liquid crystal display of the present invention will be described with reference to FIG. 8A.

First, a metal layer is deposited on the lower substrate 100 and selectively removed to form a gate line 110 having the gate electrode 110a, and the front surface of the lower substrate 100 including the gate line 110. A gate insulating layer 140 is formed on the substrate.

Subsequently, a metal layer is deposited on the gate insulating layer 140 and selectively removed to form a data line 120 in a direction perpendicular to the gate line 110. In this case, in the same process of forming the data line, source / drain electrodes are formed, and a plurality of first common electrodes 130 are formed at predetermined intervals. The common electrode 130 may be formed in the same process as the gate line 110. In the illustrated drawing, when the first common electrode 130 forms the data line 120, the first common electrode 130 is formed on the same layer since the first common electrode 130 is formed simultaneously.

The gate line 110, the data line 120, and the first common electrode 130 may be formed of metal such as Cu, Cr, Mo, Al, Ti, Ta, or Al alloy.

Subsequently, the protective layer 160 is deposited on the entire surface including the data line 120 and the first common electrode 130, and then selectively removed to form a contact hole (not shown) to expose the drain electrode 120b. do.

The passivation layer 160 is formed of an organic insulating layer having a low dielectric constant such as photoacryl, BCB (BenzoCycloButene), polyamide (Polyamide) compound, etc., in the same component as the gate insulating layer 140.

The low dielectric constant organic insulating layer prevents a vertical electric field from the upper substrate 200 by wiring such as the gate line 110 or the data line 120 of the lower substrate 100 or the first common electrode 130. The crosstalk phenomenon can be controlled.

Subsequently, the entire surface of the transparent metal layer is deposited and then selectively removed to form a plurality of pixel electrodes 160 in a region corresponding to the plurality of first common electrodes 130.

The pixel electrode 150 is formed of an indium tin oxide (ITO) -based transparent electrode. That is, the pixel electrode 150 is formed using any one of indium oxide, zinc oxide, indium-tin composite oxide film, tin-antimony composite oxide, zinc-aluminum composite oxide film, and indium-zinc composite oxide.

In order to form the transverse electric field, each of the first common electrode 130 and the pixel electrode 150 are formed to be spaced apart from each other by a predetermined interval, and are formed in the same process as the gate line 110 or the data line 120. Not required.

Subsequently, a first alignment layer 170 made of polyimide or a photo-alignment material is formed on the entire lower substrate 100 including the passivation layer 160 and the pixel electrode 150.

In addition, the light blocking layer 210 is formed on the upper substrate 200 so as to correspond to a portion except the pixel region in order to block light leakage to an area other than the pixel region.

Subsequently, in order to implement color hues R, G, and B, the color filter layer 220 is formed by overlapping each pixel region and the light blocking layer 210.

Subsequently, a second common electrode 230 is formed at a portion corresponding to the pixel electrode 150 formed on the lower substrate 100.

The second common electrode 230 is formed of any one metal, such as Cu, Cr, Mo, Al, Ti, Ta, Al alloy.

Subsequently, a second alignment layer 170 made of polyimide or a photo-alignment material is formed on the entire upper substrate 200 including the second common electrode 230.

Here, the upper and lower substrates 200 and 100 are formed on the surfaces facing each other, and the first and second alignment layers 170 and 240 made of polyimide have an orientation direction determined by mechanical rubbing, and are made of PVCN material or polysiloxane. The orientation direction of the photo-orientation material which consists of a system material is determined by irradiation of light, such as an ultraviolet-ray. At this time, the orientation direction is determined by the irradiation direction of the light or the property of the irradiated light, that is, the polarization direction.

Subsequently, the liquid crystal layer 300 is formed by injecting a liquid crystal having a positive dielectric anisotropy between the lower substrate 100 and the upper substrate 200.

On the other hand, the transverse electric field type liquid crystal display device of the present invention, unlike the in-plane switching liquid crystal display device in general, to implement a normally white (Normally White), on the back of the upper and lower substrates (200, 100) The attached first and second polarizers (not shown) have polarization axes intersected by 90 ° to each other, and the first and second alignment layers 170 and 240 have a 45 ° angle with respect to the polarization axes of the first and second polarizers. Orientation to have an orientation direction.

Orientation directions of the first and second alignment layers 170 and 240 may be provided with respect to a length direction of the first common electrode 130 or the pixel electrode 150 to give an asymmetric characteristic of liquid crystal movement when voltage is applied. Rub to have an angle of 10 ° to 20 °.

Hereinafter, the driving of the transverse electric field type liquid crystal display device will be described.

As shown in FIG. 8A, the liquid crystals before voltage application are arranged along the rubbing directions of the first and second alignment layers 170 and 240 formed on the lower substrate 100 and the upper substrate 200, respectively.

Accordingly, when the first and second alignment layers 170 and 240 are rubbed to have an angle of 10 ° to 20 ° with respect to the length direction of the pixel electrode 150 or the first and second common electrodes 130 and 230. Since the liquid crystals are arranged along the rubbing direction, the shapes of the liquid crystals located on the lines II-II 'of FIGS. 7A and 7B become nearly circular.

As shown in FIG. 8A, the optical mode of the transverse electric field type liquid crystal display device according to the present invention is normally white, and a polarizing plate is formed on the rear surface of the lower substrate 100 and the upper substrate 200, respectively. The first and second alignment layers 170 and 240 are formed to have polarization axes perpendicular to each other, and are aligned to have a 45 ° angle with the polarizer.

Accordingly, a white mode in which light is transmitted before voltage is applied is implemented. As described above, the transverse field type liquid crystal display of the present invention does not follow normally black when a vertical electric field is formed between the pixel electrode 150 and the second common electrode 230 when voltage is applied. This is because the transmission of light on the pixel region is blocked by the liquid crystals arranged in accordance with the vertical electric field.

As shown in FIG. 8B, when voltage is applied to the pixel electrode 150 and the first and second common electrodes 130 and 230, between the pixel electrode 150 and the first common electrode 130 formed on the same substrate. A horizontal electric field is formed, a vertical electric field is formed between the pixel electrode 150 and the second common electrode 230 on different substrates, and the liquid crystals are arranged along each electric field formed for each part.

In the liquid crystal display device having a distance between the first common electrode 130 and the pixel electrode 150 of 5 to 8 μm and generally having a liquid crystal cell gap of 4 to 6 μm, the first and second common electrodes 130, When the same common voltage is applied to 230, a vertical electric field is smoothly formed compared to the horizontal electric field. Accordingly, there is no problem in that the liquid crystal positioned directly above the pixel electrode rises.

At this time, as shown in FIG. 8B, the shape of the liquid crystal in the vertical direction (II to II ') of the first common electrode 130 and the pixel electrode 150 is the first common electrode 130 and the pixel electrode 150. Since the liquid crystal is arranged in the direction in which the horizontal electric field is formed, the long oval liquid crystal, which is the shape of the original liquid crystal, appears to be in a lying state, and the vertical electric field is formed between the second common electrode 230 and the pixel electrode 150. Since the liquid crystals are arranged, the long oval liquid crystals appear to stand.

Therefore, in the transverse electric field type liquid crystal display device of the present invention, which must exhibit a black state after voltage application, when each pixel electrode 150 and the first common electrode 130 form a horizontal electric field when voltage is applied, the pixel electrode ( By forming a vertical electric field between the 150 and the second common electrode 230 to smoothly drive the liquid crystal on the pixel electrode 150, light leakage may occur in the vicinity of the pixel electrode 150. It is preventing.

Here, since the first common electrode 130 is formed of any one metal of metals such as Cu, Cr, Mo, Al, Ti, Ta, and Al alloys, a horizontal electric field with the pixel electrode 150 after voltage is applied. Is formed, even if the liquid crystal of the upper portion is not smooth driving can block the light leakage phenomenon.

In the transverse field type liquid crystal display of the present invention, the liquid crystal between the first common electrode 130 and the pixel electrode 150 formed on the lower substrate 100 is driven in an in plane switching mode, and the pixel Between the electrode 150 and the second common electrode 230 formed on the upper substrate 200 is operated in the ECB mode (Electrically Controlled Birefringence mode).

Here, both the second common electrode 230 and the pixel electrode 150 formed at the same site on the upper and lower substrates 200 and 100 are formed of ITO series transparent electrodes, thereby increasing the transmittance of the white state before voltage application.

The above-described transverse electric field type liquid crystal display of the present invention has the following effects.

First, a vertical electric field is formed by forming a transparent common electrode on the upper substrate corresponding to a portion where the pixel electrode of the lower substrate is formed, thereby preventing light leakage from the pixel electrode region, and forming a horizontal electric field with the pixel electrode of the lower substrate. The common electrode may be formed of an opaque metal to prevent light leakage occurring near the common electrode.

Secondly, in the normally white mode, the second common electrode may be formed as a transparent electrode, and thus the transmittance may be improved by transmitting the portion to which the pixel electrode is formed.

Claims (16)

A lower substrate and an upper substrate; An insulating film formed on the entire surface of the lower substrate; A plurality of first common electrodes formed on the insulating layer at regular intervals; A protective film formed on an entire surface of the lower substrate including the first common electrode; A pixel electrode formed on the passivation layer between the first common electrode; A second common electrode formed on the upper substrate to correspond to the pixel electrode; And a liquid crystal layer formed between the upper and lower substrates. The method of claim 1, First and second alignment layers formed on opposite surfaces of the upper and lower substrates; And a polarizing plate on the rear surface of the upper and lower substrates perpendicularly intersecting with each other and having a transmission axis of 45 ° with respect to the alignment direction of the alignment layer. The method of claim 1, And the first and second common electrodes are metals different from each other. The method of claim 1, And the first common electrode is made of any one metal of Cu, Cr, Mo, Al, Ti, Ta, and an Al alloy. The method of claim 1, And the pixel electrode and the second common electrode are the same metal. The method of claim 1, And the second common electrode is any one of indium oxide, zinc oxide, indium-tin composite oxide film, tin-antimony composite oxide, zinc-aluminum composite oxide film, and indium-zinc composite oxide. The method of claim 1, The first and second common electrodes of claim 1, wherein the same common voltage signal is applied. The method of claim 1, And said liquid crystal layer is made of a liquid crystal having a positive dielectric anisotropy. Preparing upper and lower substrates; Forming an insulating film on an entire surface of the lower substrate; Forming a plurality of first common electrodes having a predetermined interval on the insulating film; Forming a protective film on an entire surface of the lower substrate including the first common electrode; Forming a pixel electrode on the passivation layer between the first common electrode; Forming a first alignment layer on an entire surface of a lower substrate including the pixel electrode; Forming a second common electrode on the upper substrate to correspond to the pixel electrode; Forming a second alignment layer on an entire surface of the upper substrate including the second common electrode; Forming first and second polarizing plates on a rear surface of the upper and lower substrates; And forming a liquid crystal layer between the upper and lower substrates. The method of claim 9, The first and second polarizers have a vertical polarization axis, The transmission axis of the said 1st, 2nd polarizing plate is formed at a 45 degree angle with respect to the orientation direction of the said 1st, 2nd alignment film, The manufacturing method of the transverse electric field type liquid crystal display device characterized by the above-mentioned. The method of claim 9, And the first and second common electrodes are metals different from each other. The method of claim 9, And the first common electrode is made of any one metal of Cu, Cr, Mo, Al, Ti, Ta, and an Al alloy. The method of claim 9, The pixel electrode and the second common electrode are the same metal, the manufacturing method of the transverse field-type liquid crystal display device. The method of claim 9, The second common electrode may be any one of indium oxide, zinc oxide, indium-tin composite oxide film, tin-antimony composite oxide, zinc-aluminum composite oxide film, and indium-zinc composite oxide. Way. The method of claim 9, And the same common voltage signal is applied to the first and second common electrodes. The method of claim 9, And said liquid crystal layer is made of a liquid crystal having a positive dielectric anisotropy.