JP2003186007A - Reflection plate, liquid crystal display element using the same and manufacturing method of liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that contrast is reduced since a tilt angle of a liquid crystal is changed, driving characteristics by applied voltage is also changed and uniform alignment is not obtained at a rubbing down part if a reflection part having a projecting part in a reflection plate for a reflection type liquid crystal display device is rubbed. <P>SOLUTION: The reduction of contrast can be prevented by providing a light shielding part at the rubbing down part of the projecting part and the improvement of contrast can be easily realized without increasing processes by forming the light shielding part by reduction treatment of an ITO electrode. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector used in a display device using liquid crystal.

[0002]

2. Description of the Related Art In recent years, portable information terminals, video tape recorders, and the like have become smaller and more portable, and the problem is to reduce the power consumption of image display devices.

The reflection type liquid crystal display device draws attention because it can realize low power consumption without a backlight because it displays the screen by utilizing sunlight or external light from indoor lighting.

However, the reflection type liquid crystal display device has a drawback that the screen becomes dark when the external light is small. That is,
The reflected image is a form in which the light incident on the liquid crystal device is once passed through the liquid crystal layer in the liquid crystal cell, reflected by the surface of the reflector provided on the back surface of the liquid crystal layer, and passed through the liquid crystal layer again to be extracted.
The amount of emitted light is considerably lower than that of incident light. In particular,
When color filters that absorb light are stacked, the decrease is remarkable.

Therefore, by applying the reflective liquid crystal element, a semi-transmissive liquid crystal element which can be used as a reflective type in an environment where external light is strong such as outdoors and as a transmissive type using a backlight in an environment where external light is weak such as at night or in a dark room. Is proposed.

This is because the reflective portion and the transmissive portion formed by forming a reflective film on the substrate are formed so that external light is reflected and displayed in the reflective portion without the backlight during reflection, and the light of the backlight is transmitted during transmission. It can be displayed in a transparent display.

[0007]

In this case, the reflection plate is provided with a convex portion having an inclination angle capable of efficiently reflecting external light on the substrate, so that the reflection plate has less parallax than a display provided with an external reflection film. A clear display is possible.

However, when such a surface is rubbed, the orientation of the alignment becomes non-uniform due to the convex shape of the reflection portion, which causes a problem that the contrast is lowered in the liquid crystal display.

[0009]

A reflector of the present invention comprises a substrate, a plurality of convex portions provided on the substrate, and a reflector provided on the substrate having the convex portion, A light-shielding region or a light-absorbing region (light-absorbing layer) is provided in a portion of the tangent of the contour line in the planar shape, which corresponds to rubbing (shadow) in rubbing. In this way, by making the portion that becomes the shadow of rubbing and the portion in which the alignment unevenness occurs a light-shielding region, it is possible to prevent the display from being adversely affected even if the alignment unevenness occurs.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

(Embodiment 1) FIG. 5 is a plan view showing a convex portion of a semi-transmissive liquid crystal display device. FIG. 6 shows a sectional view of FIG. As shown in FIGS. 5 and 6, the transflective liquid crystal display device includes a substrate 1 made of an insulating glass substrate, a counter substrate 2 facing the substrate 1, and a liquid crystal provided between the substrate 1 and the counter substrate 2. And a layer 3. Board 1
The cell gap between the counter substrate 2 and the counter substrate 2 is provided at a predetermined interval.

Inside the counter substrate 2, R is provided for each pixel.
The color filter 4 is provided so that each color of (red), G (green), and B (blue) corresponds. Further, a common electrode 5 made of a transparent electrode is provided inside the color filter 4. A retardation plate 6 and a polarizing plate 7 are provided outside the counter substrate 2.

A driving element 12, a plurality of source signal lines 13, a gate signal line 14, a plurality of convex portions 8 and a transmissive portion 9 are provided on the substrate 1. The drive element 12 is connected to the source signal line 13 via the source terminal 12a. Further, the driving element 12 is connected to the gate signal line 14 via the gate terminal 12c.

The protrusion 8 is made of an insulating material such as photoresist. A photoresist is applied onto the substrate 1 by a spin coating method to have a thickness of about 2 μm, and after prebaking, a pattern is formed in a predetermined shape by irradiating ultraviolet rays using a photomask. Depending on the type of resist, the edge becomes gentle after baking, and a convenient uneven pattern is formed.

Further, a reflective film 10 is formed on the substrate 1. Aluminum, silver, respective alloys or the like can be used for the reflective film.

The reflective film 10 covers the convex portions, and the portion between the convex portions is patterned as a gap portion. Then, the transparent electrode layer 1 made of ITO is formed on the entire portion with and without the reflective film.
1 is formed.

The transparent electrode layer 11 is formed independently for each pixel. Further, the transparent electrode layer 11 is the driving element 1
The second drain terminal 12b is electrically connected to the second drain terminal 12b through the contact hole 15 and also serves as a pixel electrode. With this configuration, the drive element 12 can change the voltage applied between the transparent electrode layer 11 of the pixel electrode and the common electrode 5 on the counter substrate, and the orientation of the liquid crystal element is changed to enable display. .

In FIG. 6, light incident from the outside of the polarizing plate 7 passes through the polarizing plate 7, the retardation plate 6, the counter substrate 2, the color filter 4, the common electrode 5, the liquid crystal layer 3, and the reflection film 10.
Is reflected by the observer, and enters the observer's eye through the reverse path. At this time, by controlling the voltage applied to the liquid crystal layer 3 with the driving element 12, the reflection and absorption of light can be controlled. Further, when the amount of external light is small, the backlight 17 is turned on, light is incident on the liquid crystal layer through the transmissive portion 9 of the substrate 1, and reaches the eyes of the observer together with the reflected light.

The liquid crystal layer 3 comprises a common electrode 5 and a transparent electrode layer 11.
The liquid crystal is aligned in a certain direction by applying an alignment film on the above and rubbing. However, due to the shape of the protrusion,
There was a problem that unevenness occurred in rubbing, and when the liquid crystal orientation was disturbed and displayed, the contrast was lowered. As a result of examining the location of rubbing unevenness,
It was found that when there is a convex portion in the direction of rubbing, it occurs in the shadow portion. When the rubbing conditions were strengthened in an attempt to uniformly rub, the underlayer film was sometimes peeled off. FIG. 7 shows a schematic diagram of the rubbing direction and the alignment of the liquid crystal in the convex portion. In the convex portions A and B, the tilt angle is different with respect to the substrate because the orientation due to rubbing makes the inclination of the convex portion different. For this reason, when a voltage is applied to the liquid crystal, there is a difference in the rising edges of A and B even if the voltage is the same, and in the transmissive mode by the backlight, light leakage occurs at the B portion, and the contrast is significantly reduced.

Therefore, a light-shielding layer is provided on the rubbing rubbing (shadow) portion. FIG. 1 shows an example thereof.
First, after forming a convex portion, a reflective film was processed into a predetermined pattern in a region including a scraped portion of the convex portion. Next, after the ITO film is formed on the entire surface, the exposed area of the ITO is covered with a resist other than a predetermined area including the abrasion portion.
The film was reduced and blackened. By this method, it was possible to improve the contrast by forming a light-shielding portion in the rubbing-down portion that causes uneven rubbing. This reduction treatment can be easily performed by a development process without increasing the number of processes by changing the drawing layout of the photomask by using the redox reaction of the ITO film and the Al film. At this time, if a reflective film forming region is provided on the entire surface other than the abrasion portion and the reflective film forming region is locally patterned, a semi-transmissive liquid crystal display device is obtained.

(Second Embodiment) In the first embodiment, the light-shielding portion is simply formed by the redox treatment utilizing the potential difference between two kinds of metals. In the second embodiment, the light shielding film is formed by blackening a predetermined portion of the ITO film, which is to rub down the convex portion, by hydrogen annealing or hydrogen doping (FIG. 2). Also in this case, it was realized by covering the portion other than the predetermined portion with a resist. The process flow is shown in FIGS. In the first embodiment, the reflective film is formed before the transparent electrode to form a pattern, which can be formed by almost the same steps as the conventional process flow shown in FIG. On the other hand, in the second embodiment, the transparent electrode is formed before the reflective film, and then the reflective film is formed and patterned. In this case, a metal film other than the Al film such as silver can be used as the reflective film.

In the methods shown in the first and second embodiments, it is possible to freely change the ratio of the transmissive area and the reflective area by combining the reflective film, the ITO film and the area where the convex portion is formed.

[0023]

As described above, according to the reflector of the present invention,
A substrate, a plurality of convex portions provided on the substrate, and a reflection plate provided on the substrate having the convex portion are provided. Of the tangents of the contour line in the planar shape of the convex portion, the rubbing (shadow ) By providing a light-shielding region or a light-absorbing region in a portion corresponding to), a portion that becomes a shadow of rubbing and a portion in which alignment unevenness occurs can be set as a light-shielding area so that even if alignment unevenness occurs, display is not adversely affected. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a convex portion, a reflective film of Al, and a blackened portion of ITO.

FIG. 2 is a view showing a convex portion, a reflection film, and a blackened portion of ITO.

FIG. 3 is a diagram showing a process flow of the array substrate of the present invention (No. 1)

FIG. 4 is a diagram showing a process flow of the array substrate of the present invention (No. 2)

FIG. 5 is a diagram showing a plan view of a liquid crystal display element.

FIG. 6 is a diagram showing a cross-sectional view of a liquid crystal display element.

FIG. 7 is a diagram showing a schematic view of liquid crystal during rubbing.

FIG. 8 is a diagram showing a process flow of a conventional array substrate.

[Explanation of symbols]

1 substrate 2 Counter substrate 3 Liquid crystal layer 4 color filters 5 common electrode 6 Phase plate 7 Polarizer 8 convex 9 Transparent part 10 Reflective film 11 Transparent electrode layer 12 Drive element 12a source terminal 12b drain terminal 12c gate terminal 13 Source signal line 14 Gate signal line 15 contact holes 16 ITO blackening part 17 Backlight

Continued front page    (72) Inventor Hirofumi Yamakita             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2H042 AA02 AA09 AA26 DA02 DA04                       DA11 DA21                 2H091 FA02Y FA16Y FA34Y FB02                       FB06 FB08 FC25 GA02 HA06                       LA17

Claims (11)

[Claims] 1. A reflection plate comprising a substrate, a plurality of convex portions provided on the substrate, and a reflective film provided on the substrate having the convex portions, the rubbing of the convex portions during rubbing. A reflection plate, wherein a light-shielding layer is provided in a region including a portion corresponding to the above. 2. A reflection plate comprising a substrate, a plurality of convex portions provided on the substrate, and a reflective film provided on the substrate having the convex portions, wherein the convex portions are rubbed down during rubbing. A reflection plate, wherein a light absorbing layer is provided in a region including a portion corresponding to the above. 3. A reflection plate comprising a substrate, a plurality of convex portions provided on the substrate, and a reflection film provided on the substrate having the convex portions, the rubbing of the convex portions during rubbing. A semi-transmissive reflection plate, characterized in that a black ITO electrode is provided in a region including a corresponding portion. 4. A reflection plate comprising a substrate, a plurality of convex portions provided on the substrate, and a reflection film provided on the substrate having the convex portions, the rubbing of the convex portions during rubbing. A liquid crystal display device having a reflection plate, characterized in that a light-shielding layer is provided in a region including a portion corresponding thereto. 5. A reflecting plate comprising a substrate, a plurality of convex portions provided on the substrate, and a reflective film provided on the substrate having the convex portions, the rubbing of the convex portions during rubbing. A liquid crystal display element having a reflection plate, characterized in that a black ITO electrode is provided in a region including a portion corresponding to the above. 6. A reflection plate comprising a substrate, a plurality of convex portions provided on the substrate, and a reflective film provided on the substrate having the convex portions, the rubbing of the convex portions during rubbing. A liquid crystal display device having a semi-transmissive reflection plate, characterized in that a black ITO electrode is provided in a region including a corresponding portion. 7. A plurality of convex portions, a reflective film, and a transparent electrode are formed on an array substrate in which driving elements, gate signal lines, and source signal lines are formed in a matrix on the substrate, and then the convex portions are rubbed. A method for manufacturing a liquid crystal display element, characterized in that a black ITO electrode is formed in a region including a portion corresponding to abrasion. 8. A plurality of convex portions, a reflective film, and a transparent electrode are formed on an array substrate in which driving elements, gate signal lines, and source signal lines are formed in a matrix on the substrate, and then the rubbing of the convex portions is performed. A method for manufacturing a semi-transmissive liquid crystal display element, characterized in that a black ITO electrode is formed in a region including a portion to be worn down. 9. The method of manufacturing a semi-transmissive liquid crystal display device according to claim 8, wherein the black ITO film is formed by a reduction treatment. 10. The method of manufacturing a semi-transmissive liquid crystal display device according to claim 8, wherein the black ITO film is formed by hydrogen doping. 11. The method of manufacturing a transflective liquid crystal display device according to claim 8, wherein the black ITO film is formed by a redox reaction with a reflective film.