JP2000206505A - Substrate for reflection type liquid crystal cell, and reflection type liquid crystal display device using the substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a reflection type liquid crystal cell which shows no decrease in the reflectance and which does not require a sticking process of a reflection plate, by forming a rugged reflection layer having a rugged pattern and a reflection layer on the surface of a substrate opposite to the surface to be in contact with a liquid crystal layer. SOLUTION: A rugged reflection layer 9 having a rugged pattern and a reflection layer is formed on the surface of a substrate 5 opposite to the surface to be in contact with a liquid crystal layer. The rugged reflection layer 9 reflects the light entering at a specified angle to the normal line direction of the liquid crystal panel to produce a diffused state. In the production process of the reflection layer 9, the surface profile is transferred to the back side of the substrate where electrodes to drive the liquid crystal are to be formed, electrode films are formed, and the electrode pattern is formed in a photolithographic process, and finally the reflection layer 9 is formed. By this method, since the reflection layer 9 is directly formed on the substrate, decrease in the reflectance can be avoided and no adhesive is required. Thus, a process to stick a reflection plate to a liquid crystal panel is made unnecessary and the production yield can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflective liquid crystal panel substrate and a reflective liquid crystal display device using the substrate.

[0002]

2. Description of the Related Art Currently, liquid crystal panels are used in portable terminals and the like. In order to make a terminal or the like usable for a long time, a reflection type liquid crystal display device is used. In order to configure a reflection type liquid crystal display device, a reflection plate is required. JP 5
In -27224, a solution is provided by defining the thickness of the substrate for the image quality deterioration due to the double image of the real image and the shadow thereof, particularly in the reflection type, due to the thickness of the substrate opposite to the user. However, there are no particular restrictions on the substrate and the reflector.

[0003] Further, in the method of attaching a reflector currently used in the manufacturing process to a completed liquid crystal panel, the number of steps is increased because a reduction in reflectance and a step of attaching are required. Although this increase in the number of steps causes a decrease in yield and an increase in cost, the prior art does not provide a solution to these problems.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective liquid crystal cell substrate which solves the above-mentioned problems, and a reflective liquid crystal display device using the substrate.

[0005]

According to the present invention, there is provided a substrate for a reflection type liquid crystal cell, wherein a substrate on which a reflection layer is formed has an uneven shape and a reflection layer on a side opposite to a side in contact with the liquid crystal layer. The problem was solved by providing a reflective liquid crystal display element using the substrate.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 2 is a schematic cross section of a reflection type liquid crystal display device having a conventional structure. In FIG. 2, reference numerals 3 and 5 denote substrates of a liquid crystal cell, which sandwich liquid crystal between substrates 4 via a gapping agent 8 in the drawing. 1
Is a polarizing plate + a retardation plate (shown as one component for simplicity). Reference numeral 7 denotes a reflector. The polarizing plate + the retardation plate and the reflection plate are attached to the liquid crystal cell via adhesives 2, 6, respectively. With this configuration, the reflectance of the reflection plate 7 decreases. Further, since the reflection plate 7 is bonded to the completed liquid crystal cell, the cost is increased and the yield is reduced due to an increase in the number of steps.

FIG. 1 is a sectional view showing an example of the liquid crystal display device of the present invention. 9 is a reflection layer formed on the back surface of the substrate 5. In this configuration, unlike FIG. 2, the adhesive 6 is not required. The surface of the substrate on which the reflective layer is formed is processed into irregularities on the surface of the substrate to control the reflection characteristics of the substrate, thereby making it possible to use the reflected light efficiently according to the purpose.

[0008] The method of surface treatment of the substrate is not particularly limited as long as irregularities capable of achieving the object of the present invention can be formed on the substrate. Can be polished or etched. Further, by using a plastic substrate as the substrate for performing the surface treatment, the workability of the surface treatment is greatly improved and the processing cost is reduced. For example, a method of preparing a mold having a surface shape to be transferred to a mold and pressing a plastic substrate against the mold can be used. Since the unevenness on the substrate is a fine structure, FIG.
2 are not shown in the figure.

FIG. 3 is an example showing the shape of a reflective layer formed on a substrate. In this example, the uneven reflection layer 9 reflects light incident at a fixed angle in the normal direction of the liquid crystal panel. In addition, as shown in FIG.
Can also create a diffuse state. As a procedure for forming the reflective layer, the surface shape is transferred to the back side of the substrate surface on which the electrodes for driving the liquid crystal are formed, then the electrode is formed, an electrode pattern is formed by a photolithography process, and finally, the reflective layer is formed. Is desirably formed.

That is, since stress is applied to the substrate at the time of transferring the surface shape, a film having a function such as a transparent electrode (a function which is impaired when a tarak or the like enters) is prevented from cracking or the like. Film formation is preferred. Subsequently, before forming the reflective layer, it is preferable to form a transparent electrode and pattern it in a photolithography process. The photolithography process uses an acid or a base, so that the material of the reflective layer is not affected by these. of course,
There is a method of forming a reflective material using a material that is highly resistant to acids and bases first, or a method of forming a protective film. However, these methods require expensive materials and film forming methods, or require a large number of steps. Cause an increase.

Regarding the surface shape of the reflection plate, when a glass substrate is used, surface treatment such as roughening the glass surface on the side where the reflection plate is conventionally set is performed, and then a material for reflection is formed. It can be manufactured by the following. As a material for reflection, a metal material such as Al or Ag can be used. These metal materials can be formed into a film by a method such as vapor deposition or sputtering.

In particular, the object of the present invention can be easily realized by using a plastic material for the substrate.
The type of the plastic substrate used in the present invention is not particularly limited as long as it can perform a surface treatment for reflection. When a plastic material is used for the substrate, similar to glass, surface treatment such as roughening the surface of the plastic substrate on the side where the reflection plate was conventionally set is performed, and then the reflection plate is formed by forming a material for reflection. It can be.

In the case of a plastic substrate, surface treatment for reflection can be easily performed by, for example, pressing a mold against the substrate. In addition, the surface of the substrate can be roughened during the production of the substrate. In the case of using a plastic substrate, the film formation of the reflection material is preferably performed by a sputtering method. Also,
By using a plastic substrate, display quality can be improved (a double image due to a real image and a shadow can be avoided) and workability can be improved (processing of the substrate surface is easy).

[0014]

Embodiments of the present invention will be described below.

Embodiment 1 The pixel capacity is 160 × 160 and the pixel pitch is 200 μm.
A liquid crystal panel was manufactured using a glass substrate having a thickness of 0.7 mm. After forming irregularities on the substrate (the side opposite to the liquid crystal electrodes) on the back side of the liquid crystal panel by etching, Al was deposited to form a cell. For comparison, a cell was prepared in which the glass substrate was etched under the same conditions on the outside of the liquid crystal panel under the same conditions to form irregularities, and then a reflective plate formed with Al was bonded thereto. In the liquid crystal cell according to the present invention, the reflection intensity at the time of white display was about 5% higher than that of the cell of the comparative example.

Example 2 A substrate having the same resolution as that of Example 1 was used, and a substrate on the side to be observed by a user was a glass substrate having a thickness of 0.7 mm. A liquid crystal cell was prepared. First, using a mold, after forming irregularities on the substrate (the opposite side to the liquid crystal electrode) on the back side of the liquid crystal panel, an electrode pattern for driving the liquid crystal was formed on the PC, and Al was formed on the opposite side. A reflective layer was provided. For comparison, the two substrates constituting the liquid crystal cell have a thickness of 0.7 m.
Using a glass substrate having a thickness of m, similar irregularities were formed on the back surface by etching, and then a film was formed by using Al as a reflective layer. As a result of the comparison, the reflection intensity at the time of white display hardly changed, but the number of double images using a PC substrate was extremely small.

Example 3 At the resolution of Example 1, irregularities were formed by etching on the side opposite to the side on which the electrodes were formed, and then substrates having a reflective layer before and after a photolithography step for an electrode pattern were manufactured. . Al was used as a reflective layer material.
After forming the reflective layer on both substrates, an inorganic coat layer was formed. As a result, in the substrate on which the reflection layer was formed before the photolithography step, the reflection layer was partially damaged by the etching solution. It is considered that the used protective coat did not provide sufficient protection against the etching solution. To solve this problem, it is necessary to take measures such as increasing the thickness of the protective coat or increasing the number of layers.

No change in the reflective layer was observed on the substrate on which the reflective layer was formed after the photolithography step. It was found that by forming the reflective layer after the photolithography step, the reliability and quality of the reflective layer could be improved and the cost could be reduced.

Example 4 At the resolution of Example 1, a PC was used for the substrate, and before and after the formation of the transparent electrode material, the pattern for the reflective layer was transferred onto the substrate by a mold. After the above steps, Al was used as the material of the reflective layer in the same manner as in Example 3, and a liquid crystal cell was manufactured by a normal manufacturing process. The operation was confirmed with the circuit configuration shown in FIG. In the cell where the pattern transfer was performed after the film formation of the transparent electrode material, there was a display defect considered to be a disconnection of the electrode. On the other hand, in the cell where the pattern was transferred before the formation of the transparent electrode material, no disconnection occurred in the electrode.

Example 5 A liquid crystal cell having the resolution produced in Example 1 and using a PC for both substrates constituting the liquid crystal cell was produced. The PC on the back surface of the liquid crystal cell had its surface shape changed on the side on which the reflective layer was formed by a mold. Subsequently, an electrode pattern for driving the liquid crystal was formed on the opposite side where the surface shape was changed, and a reflection layer formed of Al was provided on the side where the surface shape was changed first. For comparison, PCs were similarly used for two substrates constituting a liquid crystal cell, and a film was formed on the back surface using Al as a reflective layer. As a result of the comparison, the reflection intensity at the time of white display was improved by 10% (compared with the comparative example) when the surface shape of the reflection layer was changed.

[0021]

[Effect] 1. Claim 1 The step of attaching the reflection plate to the liquid crystal panel becomes unnecessary,
Yield improved. In addition, a bright reflector with adjustable reflection characteristics could be provided. 2. Claim 2 It is possible to provide a substrate whose reflection characteristics are adjustable and which includes a bright reflector. 3. Claim 3 By forming the reflective layer after the etching process for forming the electrode pattern is completed, it is possible to reduce the cost of using a protective layer and a material that can withstand the etching process. By processing the surface on which the layer is formed before forming the electrode pattern, a damage to the transparent electrode was reduced and a reflective liquid crystal cell substrate capable of providing a highly reliable liquid crystal display element was obtained. 4. Claim 4 By using a plastic substrate as the substrate to be used, a reflective liquid crystal cell substrate that can improve the display quality and reduce the cost by improving the processability is obtained. 5. Claim 5 By using the reflective liquid crystal cell substrate, a reflective liquid crystal display device which has solved the conventional problems can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a liquid crystal display device of the present invention.

FIG. 2 is a schematic sectional view of a reflection type liquid crystal display device having a conventional structure.

FIG. 3 is a diagram showing an example of a shape of a reflection layer formed on a substrate.

FIG. 4 is a diagram showing another example of the shape of the reflection layer formed on the substrate.

FIG. 5 is a diagram showing a circuit in which operation of a liquid crystal cell was confirmed and performed in Example 5.

[Explanation of symbols]

 Reference Signs List 1 polarizing plate + retardation plate 2 adhesive 3 substrate of liquid crystal cell 4 between substrates via gapping agent 5 substrate of liquid crystal cell 6 adhesive 7 reflecting plate 8 gapping material 9 reflecting layer formed on back surface of substrate

Claims (5)

[Claims] 1. A reflection type liquid crystal cell substrate comprising: a substrate surface on a side opposite to a side in contact with a liquid crystal layer; and a concave and convex shape formed on the substrate and a reflection layer. 2. The reflection type liquid crystal cell substrate according to claim 1, wherein a reflection layer is formed after forming an uneven shape on the substrate surface. 3. The reflection type liquid crystal cell according to claim 1, wherein a reflection layer is formed after forming an electrode pattern for driving a liquid crystal after forming the uneven shape. Substrate. 4. The substrate according to claim 1, wherein the substrate is a plastic substrate.
4. The substrate for a reflective liquid crystal cell according to any one of Items 3 to 3. 5. A reflective liquid crystal display device comprising the reflective liquid crystal cell substrate according to claim 1. Description: