KR20020010200A - Transflective Liquid Crystal Display - Google Patents

Abstract

PURPOSE: A semi-transmissive liquid crystal display is provided to eliminate the boundary between reflection and transmission parts, at which lots of leakage light is generated, to reduce the amount of leakage light, thereby improving contrast ratio of screen. CONSTITUTION: A semi-transmissive liquid crystal display includes upper and lower substrates, a liquid crystal filled between the upper and lower substrates, and a reflective electrode(250) having a square-shaped transmission hole(240) under the liquid crystal layer. One side of the reflective electrode is opened by the transmission hole, and the portion around the transmission hole is stepped. The display further has an interlevel insulating layer formed under the reflective electrode, and a transparent electrode(230) located under the interlevel insulating layer. The display also includes a protection layer formed between the transparent electrode and the lower substrate to form a stepped portion on the reflective electrode, ad an alignment film formed between the reflective electrode and the liquid crystal layer.

Description

Transflective Liquid Crystal Display

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device, and to a transflective liquid crystal display device capable of reflective and transmissive modes. In particular, the present invention relates to a transflective liquid crystal display device having a structure for reducing leakage light generated due to a step between the reflecting part and the transmitting part.

Recently, as the era of information society progresses rapidly, a display field for processing and displaying a large amount of information is developing.

Until modern times, cathode ray tube (CRT) has become the mainstream of display devices and has been developing.

However, in recent years, the need for a flat panel display has emerged in order to meet the times of miniaturization, light weight, and low power consumption. Accordingly, a thin film transistor-liquid crystal display (hereinafter referred to as TFT-LCD) having excellent color reproducibility and thinness has been developed.

Referring to the operation of the TFT-LCD, when an arbitrary pixel is switched by the thin film transistor, the arbitrary pixel that is switched makes it possible to adjust the light transmission amount of the lower light source.

The switching element is mainly composed of an amorphous silicon thin film transistor (a-Si: H TFT) in which a semiconductor layer is formed of amorphous silicon. This is because the amorphous silicon thin film can be formed at a low temperature on a large insulating substrate such as a low-cost glass substrate.

Commonly used TFT-LCDs have used a method of representing an image by the light of a light source called a backlight located under the panel.

However, TFT-LCDs are very inefficient light modulators that transmit only 3-8% of the light incident by the backlight.

The transmittance of the two polarizers is 45%, the lower and upper plates are 94%, the TFT array and the pixel are about 65%, and the color filter's transmittance is 27%. About 7.4%.

1 is a diagram schematically illustrating transmittance of each layer of light emitted from a backlight.

As described above, since the amount of light actually seen through the TFT-LCD is about 7% of the light generated in the backlight, the brightness of the backlight should be bright in the high brightness TFT-LCD, and power consumption by the backlight is large.

Therefore, in order to supply sufficient backlight power, a battery having a large weight has been used by increasing the capacity of the power supply device. However, this also has a limitation in the use time.

In order to solve the above problem, a reflective TFT-LCD which does not use backlight light has recently been studied. Since it operates by using natural light, the power consumption of the backlight can be greatly reduced, so that it can be used in a portable state for a long time, and the aperture ratio is also superior to that of a conventional backlight TFT-LCD.

That is, the reflective TFT-LCD has a structure that reflects external light by using a material having an opaque reflective characteristic in the pixel portion formed of the transparent electrode in the conventional transmissive TFT-LCD.

The reflective TFT-LCD as described above can be used for a long time because it is driven using natural light or an external artificial light source without using an internal light source such as a backlight. That is, the reflective TFT-LCD reflects external natural light to the reflective electrode and uses the reflected light. Therefore, only power required for driving the reflective TFT-LCD is the liquid crystal drive and the drive circuit.

However, natural or artificial light sources do not always exist. That is, the reflective TFT-LCD may be used in an office or a building in which daylight is present, or an external artificial light is present, but the reflective TFT-LCD may be used in a dark environment in which there is no natural light. There will be no.

Therefore, in order to solve the above problem, a transflective TFT-LCD using the advantages of the reflective TFT-LCD using the natural light and the transmissive TFT-LCD using the backlight has recently been researched and developed.

The transflective TFT-LCD is free to switch to a reflective or transmissive mode according to the user's will.

2 is a cross-sectional view showing a cross section of a conventional transflective liquid crystal display device.

As shown in the lower substrate 20, the first transparent substrate 28 and the first transparent substrate 28 are formed with a reflective electrode 30 forming a reflecting portion and a transparent hole forming a transmitting portion 32. It is.

A first retardation film (Quarter Wave Plate (λ / 4 plate); " QWP ") 26 and a lower polarizing plate 24 are formed under the first transparent substrate 28. The backlight 22 is positioned below the lower polarizer 24.

In addition, a transparent electrode 42 is formed on the upper substrate 40 in a direction facing the second transparent substrate 44, the reflective electrode 30, and the transmission hole 32, and the second transparent substrate 44. ), A second QWP 46 is formed in a direction corresponding to the transparent electrode 42, and an upper polarizer 48 is formed on the second QWP 46.

In addition, a liquid crystal layer 34 is formed between the upper substrate 40 and the lower substrate 20 to control the path of light.

The first and second QWPs 26 and 46 may change a polarization state of light. In other words, the linearly polarized light is converted into left or right circularly polarized light and the left or right circularly polarized light is linearly polarized.

In the transflective liquid crystal display of the above structure, when the light incident on the upper polarizer is circularly polarized light (right polarized light), the light passing through the upper polarizer is weakened in half compared to the intensity of light before passing through the upper polarizer. Will be output as That is, white light should be output, but dark gray.

The above-mentioned phenomenon occurs because the cell gaps, i.e., d1 and d2, in the reflecting portion and the transmitting portion are substantially the same, and in general, the design criteria of the transflective liquid crystal display device are manufactured based on the reflection mode.

In order to solve the above problems, a semi-transmissive liquid crystal display device forming a step between the reflecting portion and the transmitting portion has been proposed.

3 is a cross-sectional view of a transflective liquid crystal display device having a step between a reflecting portion and a transmitting portion.

The transflective liquid crystal display of FIG. 3 may be divided into four parts. That is, the reflective electrode 62 includes a backlight 84, a lower substrate 50, a liquid crystal layer 66, and an upper substrate 70, and in particular, includes a transmission hole 64 on the lower substrate 50. Is formed.

In addition, upper and lower polarizing plates 82 and 52 are formed on outer surfaces of the upper substrate 70 and the lower substrate 50, respectively.

Hereinafter, a description overlapping with the structure of the transflective liquid crystal display of FIG. 2 will be omitted.

The step difference between the reflection part r on which the reflective electrode 62 is formed and the transmission part t on which the transmission hole 64 is formed is determined whether the protective layer 109 is formed below the transparent electrode 58. The reason why the cell gap is different between the two modes by forming a step is to increase the efficiency of light passing through the liquid crystal layer 66 filled in the transmission hole 64 in the transmission mode.

Hereinafter, it demonstrates in detail with reference to Formula (1) and (2) which show a phase difference value.

d3Δn = λ / 4 --- (1)

Since d4 = 2d3 --- (2), it has d4Δn = λ / 2 characteristic.

In Equation (1), d3 is a cell gap of the liquid crystal layer positioned on the reflective electrode, d4 is a cell gap of the liquid crystal layer formed by filling the transmission hole, and λ / 4 is an upper portion of the reflective electrode 62 in the reflection mode. It is a phase change value of light passing through the liquid crystal layer 66 once.

In the dark state in the transmission mode, the linearly polarized light passing through the lower polarizing plate 52 is reversed in the direction of linearly polarized light by a phase value of λ / 2.

Since the linearly polarized light is completely absorbed by the upper polarizing plate 82, it may exhibit a clear dark characteristic.

However, the transflective liquid crystal display device having the steps between the reflecting portion and the transmitting portion has the following problems.

By designing and forming the cell gap of the transmissive part twice as much as the reflecting part, when voltage is applied, electric field distortion occurs due to the electrode step between the reflecting part and the transmissive part, and the alignment direction of the liquid crystal becomes uneven at the stepped part, resulting in leakage light. Done.

That is, the leaked light has a problem of acting as a factor to lower the contrast (CR) of the screen.

FIG. 4 is a plan view of a lower substrate corresponding to one pixel part of FIG. 3, and is presented to examine a problem of the structure of the transflective liquid crystal display.

The gate wiring 100 is formed in the horizontal direction, and the gate electrode 102 extending from the gate wiring 100 is formed.

In addition, a data line 104 is formed in a vertical direction, intersects with the gate line 100, and a source electrode 106 extending from a data line 104 near the gate electrode 102 is formed. The electrode 102 is formed to overlap a predetermined area.

In addition, a drain electrode 108 is formed at a position corresponding to the source electrode 106 with respect to the gate electrode 102.

The drain electrode 108 is in contact with the transparent electrode 58 and the reflective electrode 62 through the contact hole 110 formed on the drain electrode 108.

In addition, a reflective electrode 62 is formed on the transparent electrode 58. The central portion of the reflective electrode 62 includes a transmission hole, and the transparent electrode 58 is exposed through the transmission hole 64.

The arrow indicates the rubbing direction of the lower plate of the transflective liquid crystal display. When rubbing to the left and to the right as shown in the drawing, the parallel alignment liquid crystal is oriented in the direction when voltage is applied, so that the reflective portion and the transmissive portion At the right side of step, the leakage light is most severe.

FIG. 5A is a view showing an arrangement of horizontally aligned liquid crystals. As shown in FIG. 5, in the parallelly aligned liquid crystal mode, the liquid crystals 68 filled between the upper and lower substrates 70 and 50 are disposed at the left side. When forming the rubbing direction (I) to the right, the liquid crystal (68) that touches the upper and lower substrates (70, 50) when voltage is applied forms a pretilt angle (θ) of a constant angle from left to right, Accordingly. At this time, when the lower plate rubbing direction (I) is from left to right, the leakage light at the right step portion is most severely generated, and the leakage light due to the electric field distortion is eliminated by removing the right step between the reflecting portion and the transmitting portion of the transflective liquid crystal display. The phenomenon can be significantly reduced.

FIG. 5B is a diagram illustrating an arrangement direction of liquid crystals along a rubbing direction in a twist nematic liquid crystal mode. FIG.

When rubbing is applied to the upper substrate (not shown) and the lower substrate 50 so as to be orthogonal to each other in the directions Ia and Ib, the alignment direction of the liquid crystal in the middle portion of the liquid crystal layer, which plays a substantial role of controlling light, is the "D" direction. Therefore, the right step of the reflecting portion and the transmitting portion may be removed as in the "D" direction.

That is, in the transflective liquid crystal display device of the liquid crystal mode in which the rubbing directions of the upper and lower substrates are perpendicular, the step portions to be removed from the reflecting portion and the transmitting portion are determined according to the alignment direction of the intermediate liquid crystal according to the application of voltage.

For reference, in the present specification, the description will focus on the horizontally aligned liquid crystals in which the rubbing directions of the upper and lower substrates are the same, but the application in the TN liquid crystal mode in which the rubbing directions of the upper and lower substrates are vertical is possible as described above. .

FIG. 6 shows a semi-transmissive liquid crystal display device having a stepped portion formed on the reflecting portion and the transmitting portion, and a voltage is applied to the reflecting portion r and the transmitting portion t using a two-dimensional liquid crystal simulation program called 2 MOS. When applied, it shows the arrangement direction of the liquid crystal in accordance with the direction of the equipotential line and the electric field.

As shown, an equipotential line 69 is formed in a direction parallel to the substrate when voltage is applied, an electric field is formed in a direction perpendicular to the equipotential line 69, and the parallel alignment liquid crystal 68 is formed on the upper and lower substrates. The abutting portion of the forms a pretilt angle, and the middle portion is arranged vertically with respect to the substrate as in the electric field direction.

At this time, in the step s between the reflecting portion r and the transmitting portion t, the equipotential line 69 is also bent, thereby causing electric field distortion, and in the same direction as the electric field distortion line, the liquid crystal 68 ) Is arranged, so that the direction of the liquid crystal 68 in the step (s) is scattered differently from other parts.

That is, in the step (s) where the direction of the liquid crystal 68 is scattered, when voltage is applied, light cannot be controlled and leakage light is generated, resulting in a low CR on the screen.

SUMMARY OF THE INVENTION In order to overcome the above-described problems, an object of the present invention is to provide a transflective liquid crystal display device having a structure for reducing leakage light generated at the level of the reflecting portion and the transmitting portion, thereby improving the CR of the screen.

That is, the transflective liquid crystal display device of the present invention is intended to solve the above problem by removing the boundary between the reflection portion and the transmission portion where leakage light is most severe.

1 is a diagram showing the transmittance of each layer of light emitted from the backlight.

2 is a cross-sectional view showing a cross section of a conventional transflective liquid crystal display device.

3 is a cross-sectional view of a general transflective liquid crystal display device having a step formed between a reflecting portion and a transmitting portion.

4 is a plan view of a lower substrate corresponding to one pixel portion of a transflective liquid crystal display;

5A is a diagram illustrating an arrangement state of liquid crystals along a rubbing direction of parallel alignment liquid crystals;

FIG. 5B is a diagram illustrating an arrangement state of liquid crystals along a rubbing direction in a twisted nematic liquid crystal mode; FIG.

FIG. 6 is a diagram showing an electric field distribution across a transmissive portion in a reflecting portion of the transflective liquid crystal display of FIG. 3.

7 is a plan view showing a lower substrate corresponding to one pixel portion of the transflective liquid crystal display of the present invention.

8A to 8E are process diagrams illustrating a manufacturing process of a cross section taken along a cutting line A-A 'of FIG. 7.

9 is a cross-sectional view taken along the line BB ′ of FIG. 7.

10 and 11 are plan views illustrating lower substrates corresponding to one pixel portion of a transflective liquid crystal display according to another exemplary embodiment of the present invention.

12 is a view showing an electric field distribution across a transmissive portion in a reflecting portion of a transflective liquid crystal display of the present invention.

<Description of Symbols for Main Parts of Drawings>

200: gate wiring 202: gate electrode

204: data wiring 206: source electrode

208: drain electrode 210: drain contact hole

230: transparent electrode 240: through hole

250: reflective electrode

In order to achieve the above object, the present invention, the upper and lower substrates; A liquid crystal filled between the upper and lower substrates; A reflective electrode having a quadrangular through hole in the lower portion of the liquid crystal, a part of one side being opened by the through hole, and stepped around the through hole; An interlayer insulating film formed under the reflective electrode; A transparent electrode under the interlayer insulating film; A protective layer disposed between the transparent electrode and the lower substrate to form a step in the reflective electrode; The present invention provides a transflective liquid crystal display including an alignment layer disposed between the reflective electrode and the liquid crystal.

The opening of one side of the reflective electrode in contact with the transmission hole is determined according to the rubbing direction of the alignment layer, and the reflective electrode is made of one of an aluminum-based metal having low reflectivity and excellent reflectance.

In addition, the transparent electrode that transmits light to the outside through the through hole is made of any one of a transparent conductive material ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), the protective layer is an organic insulating film BCB (BenzoCycloButene) Characterized in that made.

Hereinafter, for better understanding, the transflective liquid crystal display according to the present invention will be described with reference to the accompanying drawings.

FIG. 7 is a plan view of a lower substrate corresponding to one pixel part of the transflective liquid crystal display according to the present invention, and a part overlapping with the above description in FIG. 4 will be omitted.

As illustrated, the gate wiring 200 is formed in the horizontal direction, and the gate electrode 202 extending from the gate wiring 200 is formed.

The data line 204 is formed in the vertical direction, and the source electrode 206 extending from the data line 204 in the vicinity of the gate electrode 202 is formed to overlap the gate electrode 202 by a predetermined area. do.

In addition, a drain electrode 208 is formed at a position corresponding to the source electrode 206 with respect to the gate electrode 202.

The drain electrode 208 is in contact with the pixel portion with two different materials through the drain contact hole 210 formed on the drain electrode 208. That is, the reflective electrode 250 is formed of a substantially opaque metal material and the transparent electrode 230 made of a transparent conductive material, the reflective electrode 250 includes a transmission hole 240, such a transmission hole ( The lower transparent electrode 230 is exposed by the 240. In this case, since the lower plate rubbing direction II of the liquid crystal is made from left to right, the right level difference between the reflective portion and the transparent portion of the transflective liquid crystal display device is removed, and thus the right boundary line between the reflective electrode 25 and the transmission hole 240 is removed. This was removed.

The through hole 240 is preferably square.

That is, the reflective electrode 250 is formed in the shape of a recess in which the transmission hole 240 and one side contact.

The boundary between the reflective electrode 250 and the transmission hole 240 is a region in which leakage light is severely generated when a voltage is applied, thereby removing the step difference between the reflective electrode 250 and the transmission hole 240 in the region. The problem can be solved.

For reference, the reflective electrode 250 overlaps the adjacent gate wiring 200 and the data wiring 204 by a predetermined interval, and enlarges the display area. This is because the light efficiency is used because only external light is used without a backlight when the screen is implemented only in the reflective mode. To increase it.

8A to 8E are process charts showing the fabrication process of the section taken along the cut line A-A 'of FIG.

FIG. 8A illustrates a step of forming the gate electrode 202 on the substrate 231. The gate electrode 202 may be made of metal, such as chromium and tungsten, having high corrosion resistance, and a low resistance aluminum alloy. Used.

8B illustrates a gate insulating film 232 and a semiconductor layer 234 made of an insulating material such as a silicon nitride film formed on a substrate 231 on which the gate electrode 202 is formed, and on the semiconductor layer 234. The steps of forming the source and drain electrodes 206 and 208 formed at predetermined intervals on the substrate are shown.

Subsequently, as shown in FIG. 8C, a protective layer 209 made of BCB, which is an organic insulating layer, is formed on the source and drain electrodes 206 and 208, and then in the first drain contact hole 210a and the pixel portion. The gate insulating layer contact hole 212 is formed to expose some gate insulating layer 232 in the drain electrode 208 and the pixel portion.

The BCB used as the protective layer 209 has excellent step characteristics, and is suitable for forming a desired step between the reflective electrode and the through hole later.

8D, a transparent electrode 230 made of a transparent conductive material is formed to contact the first drain contact hole 210a, and an interlayer insulating film is formed of a silicon nitride film having a transparent insulating material on the transparent electrode 230. After forming 233, a second drain contact hole 210b is formed in the drain contact hole 210 to expose the transparent electrode 230.

The interlayer insulating layer 233 has excellent light transmittance and is formed of a silicon nitride film (SiNx) that can be thinly deposited, and the interlayer insulating layer 233 has a galvanic corrosion between the reflective electrode 250 and the transmission hole 240. It serves to prevent corrosion.

Galvanic corrosion occurs when two metals are in electrical contact in an electrolyte solution. In a transflective liquid crystal display, if a transparent electrode is formed on a substrate and a reflective electrode is formed immediately without forming an insulating layer, the reflective electrode In the process of patterning the transparent electrode exposed through the through hole of the solution, since the developer and the etching solution of the process exhibit an electrolyte, ITO (Indium Tin Oxide) or IZO (Indium), which is a transparent conductive material in the electrolyte solution. A transparent electrode made of zinc oxide and a reflective electrode made of an opaque metal made of Al (Aluminum) and AlNd (Aluminum Neodymium) are in contact with each other to generate corrosion.

At this time, the relatively damaging metal is a transparent conductive material of ITO, IZO, because the transparent conductive material is formed relatively thin, it is easy to lose transparency through the corrosion phenomenon.

As shown in FIG. 8E, in forming the reflective electrode 250 in contact with the transparent electrode 230 through the second drain contact hole 210b, the reflective electrode 250 is an opaque metal and has a reflective property. It is preferable to use aluminum-based materials such as Al, AlNd and the like. After forming the reflective electrode 250, the reflective electrode 250 is patterned to form a through hole 240 through which the interlayer insulating film is exposed, and an alignment layer 251 is formed on the entire surface of the substrate.

The step between the reflective electrode 250 and the transmission hole 240 is caused by the presence or absence of the protective layer 209, and the step causes the leakage light.

The alignment layer 251 is rubbed in a predetermined direction so that the liquid crystal can be aligned in a desired direction when voltage is applied.

That is, when the rubbing of the alignment layer 251 is performed from left to right, in the case of parallel alignment liquid crystal when voltage is applied, the alignment is oriented in a vertical direction from left to right. Can be effectively reduced.

That is, when looking at the cross section of one pixel portion of the transflective liquid crystal display of the present invention, it can be seen that there is only one region where a step occurs between the reflecting portion and the transmitting portion.

In other words, the step difference in the region where the leakage current is severely generated along the rubbing direction of the liquid crystal is removed. According to the above structure, the effect obtained by changing the cell gap between the reflecting portion R and the transmissive portion T is maintained while maintaining the same effect as before. Leakage can be reduced by more than 50%

In addition, compared with the manufacturing process of the transflective liquid crystal display device having a step between the reflective portion and the transmissive portion, there is an advantage that can be manufactured without an additional process.

That is, according to the above structure, not only the efficiency of light in the transmission mode can be increased, but also the leakage light generated in the reflection part and the transmission part can be reduced, thereby improving the image quality.

FIG. 9 is a cross-sectional view illustrating a cross section taken along a cutting line BB ′ of FIG. 7.

As shown, the transflective liquid crystal display device of the present invention comprises: upper and lower substrates 331 and 231, and a liquid crystal 168 filled between the upper and lower substrates; The reflective electrode 250 including the transmission hole 240 under the liquid crystal 168, the interlayer insulating layer 233 formed under the reflective electrode 250, and the transparent electrode under the interlayer insulating layer 233. A protection layer 209 disposed between the transparent electrode 230 and the lower substrate 231 to form a step with the transmission hole 240 in the reflective electrode 250; And an alignment layer 251 disposed between the reflective electrode 250 and the liquid crystal 168.

10 and 11 are plan views corresponding to one pixel part of a transflective liquid crystal display according to another exemplary embodiment of the present invention.

When the rubbing direction of the liquid crystal is changed, the position at which the boundary line between the reflective electrode 260 and the transmission hole 262 is removed is also different. FIG. 10 shows the reflection of the left side when the rubbing direction III of the liquid crystal is right to left. By removing the stepped portion and the transmissive portion, the through hole 262 is formed in contact with the left vertical line of the reflective electrode 260.

In FIG. 11, the rubbing direction IV of the liquid crystal is from top to bottom. In the same manner as in FIG. 10, the transmission hole 266 is formed in contact with the upper horizontal line of the reflective electrode 264.

The transmission hole 266 is determined according to the patterning method after forming the reflective electrode 264. That is, the formation position of the transmission hole is determined according to the liquid crystal rubbing direction, thereby reducing leakage light as much as possible. To provide a structure.

In addition, in the transflective liquid crystal display device in which the thin film transistor portion is positioned above one pixel portion, it is also possible to form the through hole in contact with the lower horizontal line of the reflective electrode when the rubbing direction of the liquid crystal is from top to bottom.

FIG. 12 is a diagram illustrating a simulation result showing that electric field differences between the reflection part and the transmission part of the transflective liquid crystal display of FIG. 7 are reduced.

As shown in the drawing, when the rubbing direction V of the liquid crystal 168 is made from left to right, leakage light is emitted in the right vertical direction among the steps S between the reflecting portion S and the transmitting portion T as described above. Although most severely shown, according to the present invention, by removing the region, the region in which the liquid crystal 168 arranged in the direction perpendicular to the equipotential line 169 is less disturbed and thus cannot control light is reduced through the drawing. can see.

What has been described above is only one embodiment for implementing the transflective liquid crystal display device according to the present invention, and the present invention is not limited to the above-described embodiment, as claimed in the following claims. Without departing from the gist of the present invention, one of ordinary skill in the art will have the technical spirit of the present invention to the extent that various modifications can be made.

As described above, the transflective liquid crystal display device according to the present invention has the advantage of improving the light efficiency of the transmissive mode by varying the cell gap of the reflecting portion and the transmitting portion, while one step between the reflective electrode and the transmissive hole where the leakage light occurs most severely. By eliminating the, the CR of the screen can be improved, and consequently, the image quality can be improved.

Claims (5)

Upper and lower substrates; A liquid crystal filled between the upper and lower substrates; A reflective electrode having a quadrangular through hole in the lower portion of the liquid crystal, a part of one side being opened by the through hole, and stepped around the through hole; An interlayer insulating film formed under the reflective electrode; A transparent electrode under the interlayer insulating film; A protective layer disposed between the transparent electrode and the lower substrate to form a step in the reflective electrode; An alignment layer positioned between the reflective electrode and the liquid crystal Transflective liquid crystal display comprising a. The method of claim 1, The transmissive liquid crystal display according to the rubbing direction of the alignment layer is opened at one side of the reflective electrode in contact with the transmission hole. The method of claim 1, The reflective electrode is a semi-transmissive liquid crystal display device made of one of a series of aluminum-based metals having excellent resistance with low resistance. The method of claim 1, The transparent electrode which transmits light through the transmission hole to the outside is made of any one of a transparent conductive material of ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide). The method of claim 1, The protective layer is a transflective liquid crystal display device consisting of BenzoCycloButene (BCB) which is an organic insulating film.