JP3199677B2 - Manufacturing method of electro-optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an electro-optical device such as a liquid crystal display.

[0002]

2. Description of the Related Art A conventional liquid crystal display device, for example, disclosed in
In the reflective liquid crystal display device disclosed in Japanese Patent No. 188828, a reflective layer or the like is provided on a liquid crystal layer side surface of one substrate of a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of opposed substrates. It has been proposed to obtain a bright display.

However, in the above-mentioned conventional device, the reflection layer is not always clear. If a metal film or the like is formed smoothly on the surface of the substrate on the liquid crystal layer side, the reflection layer becomes a mirror surface and the face of the user is changed. And the background is reflected and the display is very difficult to see.

[0004] Therefore, a method has been proposed in which a reflective layer is formed on the surface of the substrate on the liquid crystal layer side and then heat-treated to make the surface uneven, or a honing or etching treatment is performed after the reflective layer is formed to form a light scattering surface. ing.

[0005]

However, when the surface is roughened by the heat treatment as described above, 400 to
Heat treatment in a high temperature process of 600 ° C. is required, and heat resistance of the substrate is required, and there are restrictions on the material of the substrate. In addition, since the unevenness is due to the control of the crystallinity, there is a problem that the light scattering effect is not sufficiently obtained.

As described above, when the reflective layer is honed, there is a possibility that a pinhole or the like may be formed in the reflective layer. Can not. Further, when the reflective layer is etched, there is a problem that the light scattering effect is small because the surface of the reflective layer is isotropically etched.

An object of the present invention is to provide a method for manufacturing an electro-optical device which can solve the above-mentioned problems.

[0008]

To achieve the above object, a method of manufacturing an electro-optical device according to the present invention has the following configuration. That is, in a method of manufacturing an electro-optical device having a liquid crystal layer sandwiched between a pair of glass substrates and having a reflective layer on the liquid crystal layer side of one of the glass substrates, a surface of the one glass substrate on the liquid crystal layer side. Forming an unevenness on the glass substrate, applying an organic film on the unevenness of the glass substrate, and forming a reflective layer on the organic film, the unevenness of the surface of the one glass substrate is the organic film The surface of the reflection layer becomes uneven due to the transmission through the substrate.

[0009]

[0010]

[0011]

As described above, the method of manufacturing an electro-optical device according to the present invention comprises the steps of forming irregularities on the surface of one of a pair of glass substrates sandwiching a liquid crystal layer on the liquid crystal layer side; A step of applying an organic film on the unevenness of the substrate, and a step of forming a reflective layer on the organic film, the unevenness of the surface of the one glass substrate is spread through the organic film, Since the surface of the reflective layer is made uneven, it is possible to form smooth unevenness on the surface of the reflective layer on the liquid crystal layer side without generating a pinhole or the like in the reflective layer.

[0012]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an electro-optical device according to the present invention will be specifically described with reference to a case where the present invention is applied to a liquid crystal display device.

FIG. 1 is a longitudinal sectional view showing an example of a liquid crystal display device as an electro-optical device to which the present invention is applied. In the figure, reference numeral 1 denotes a liquid crystal cell, which is formed by sandwiching a liquid crystal layer 4 between a pair of upper and lower substrates 2 and 3. A transparent electrode 5 such as ITO is provided on the surface of the upper substrate 2 on the side of the liquid crystal layer 4, and a thin metal film 6 as a reflection layer is provided on the inner surface of the other substrate 3. Reference numeral 7 denotes a spacer, and 8 denotes a polarizing plate.

In this embodiment, fine irregularities are provided on the surface of the lower substrate 3 on the side of the liquid crystal layer 4 and the thin metal film 6 is provided on the surface. Is to spread.

Incidentally, an inorganic or organic film such as SiO2 may be applied on the surface of the metal film 6 so that the thickness of the liquid crystal layer becomes uniform. In some cases, a rubbing treatment is performed on a polymer organic thin film such as polyimide or polyvinyl alcohol so that liquid crystal molecules are uniformly aligned.

[0017] As the substrate 3 of the can using a glass substrate, an acrylic resin on the surface of the glass substrate, epoxy resin, polyimide resin, polyimide amide resin, providing the organic film such as Miranol resin. Note that the substrate 3 does not necessarily need to be transparent. The substrate may be anisotropically conductive, having conductivity between the two surfaces and insulating within the surface.

[0018] intended to form an organic film after forming irregularities on the above glass substrate, the thickness of the organic film is preferably 2μm or less, and more preferably it is desirable to 0.5μm or less.

The material of the metal film constituting the reflection layer is aluminum, silver or any other material, and is not particularly limited. The thickness of the metal film is preferably 1 μm or less, more preferably 3000 Å or less.

The above-mentioned metal film can be used also as a display electrode. Further, a substrate having a transparent electrode such as ITO or an opaque electrode on the liquid crystal layer side can be used as the substrate having the metal film. Also in this case , the above-mentioned irregularities are provided on the surface of the substrate and the electrode on the liquid crystal layer side.

As described above, the unevenness is provided on the surface of the substrate on the liquid crystal layer side, and a thin metal film is provided on the surface as a reflective layer. As a scattering surface, light incident from the observation surface side (upper side in the figure) can be scattered and reflected well.

In this case, as shown in FIG. 3B, it is desirable to control so that the reflected light is increased on the observer side. For example, when the pitch of the unevenness is formed uniformly, directivity is generated in the reflected light. Since the effect does not occur uniformly in all directions, it is desirable that the pitch of the unevenness is irregularly and randomly formed as shown in FIG. In addition, the average pitch p of the irregularities in that case
Is preferably not more than 80 μm, more preferably not more than 10 μm, and the height h of the unevenness is 0.6 μm in consideration of the alignment stability of the sandwiched liquid crystal and the concentration of reflected light on the observer side. It is desirable that the thickness be 0.3 μm or less.

Next, a method for manufacturing an electro-optical device such as a liquid crystal display device as described above will be specifically described.

That is, the manufacturing method according to the present invention manufactures a liquid crystal display device or the like having a reflective layer on a liquid crystal layer side surface of one substrate of a liquid crystal cell having a liquid crystal layer sandwiched between a pair of opposed substrates. In this case, fine irregularities are formed on the surface of the substrate on which the reflective layer is formed on the liquid crystal layer side, and if necessary, the irregular surface is repaired, and then a metal film as the reflective layer is formed on the irregular surface. Things.

The means for forming the irregularities on the substrate is optional, but may be formed by, for example, a honing process.
In this case, the glass substrate may be an organic film after forming irregularities by honing.

The material of the organic film is an acrylic resin or any other suitable material, and there is no particular restriction on the film thickness. Means for forming the organic film on the glass substrate is coating or other appropriate means, and the formation position of the organic film should be selectively formed only at the position where the above-mentioned unevenness should be formed, avoiding the signal input terminal portion. Effective and desirable from the viewpoint of reliability. For example, an organic film can be formed by coating a photosensitive acrylic resin over the entire surface with a thickness of 2 μm by a spin coating method, irradiating only a desired pattern with a photomask with ultraviolet rays and performing photopolymerization, and developing the remainder.

As the abrasive particles for forming the irregularities on the substrate by the honing treatment, cerium oxide or the like is preferably used for a glass substrate, and the particle size thereof is 10 μm.
It is desirable to use one having a thickness of 5 μm or less.

Furthermore, if the honing process is performed in a vertical (vertical) direction with respect to the substrate, the height of the formed concavities and convexities becomes large, making it difficult to control. Therefore, the honing process is inclined at a predetermined angle with respect to the vertical direction. This is desirable in order to form uniform and shallow irregularities, and the above-mentioned inclination angle is preferably inclined at 45 ° or more with respect to the vertical direction.

As a method other than the honing treatment,
An effective method is to form irregularities by etching a glass substrate with hydrofluoric acid. Also, as the above-mentioned repairing process, for example, a method of lightly etching the uneven surface formed on the substrate using hydrofluoric acid, or a method of adjusting the height of the unevenness by polishing the convex portion of the unevenness can be adopted.

When the uneven surface formed on the substrate is lightly etched by using the above-mentioned hydrofluoric acid, the honed glass substrate is placed on the honed surface by hydrofluoric acid or a mixture of hydrofluoric acid and ammonium fluoride. 20 to 4 using a mixed liquid (mixing ratio of 4: 1 to 1: 4, adjusted depending on the degree)
The height and shape of the irregularities are adjusted by immersing at 0 ° C. and etching.

In the case where the convex portion is polished as described above,
The abrasive is appropriately selected according to the material of the substrate to be polished. For example, the same abrasive particles as those used in the above-mentioned honing treatment are used.

Next, a metal film as a reflection layer is formed on the substrate having the irregularities formed as described above, and is formed by a vacuum film forming method such as sputtering or vapor deposition.
In this case, the higher the film forming rate, the easier the unevenness is formed on the film, and for example, desirably about 80 to 250 Å / min. The film forming temperature is desirably about 100 to 300 ° C.

Specifically, for example, in the case of the sputtering method,
The film formation rate is about 200 Å / min,
A film forming temperature of about 180 ° C. and a film thickness of about 5000 Å may be formed. In the case of the vapor deposition method, the film forming rate is about 100 Å / min, and the film forming temperature is about 200 Å.
A film thickness of about 5000 angstroms may be formed at about ° C.

The metal film formed as described above can be made to have fine pitch irregularities by controlling the irregularities by heat treatment as needed. The heat treatment is
Bayoi performed in air at 200~450 ℃ example.

The metal film formed on the substrate as described above is patterned into a display electrode. In this case, the electrode may be formed before or after patterning, but it is preferable to heat after patterning because the etching rate of the surface where the crystallinity is changed by heat treatment changes. The above heat treatment may be performed in the air, but depending on the metal,
For example, since there is a material such as chromium that oxidizes and lowers the reflectance, it is preferable to perform the treatment in an inert gas atmosphere.

It should be noted that I is provided between the substrate and the metal film.
It is also possible to provide a transparent or opaque electrode such as TO. In this case, a metal film is formed after an electrode having a desired pattern such as ITO is formed on the substrate having the irregularities formed as described above. As the metal film may be formed by plating and nickel.

Specifically, it is formed, for example, in the following manner. That is, the substrate on which the electrodes were formed was replaced with 20% KOH.
It is immersed in a solution at room temperature for 10 minutes to perform degreasing, and is immersed in a 5% HCl solution at room temperature for 5 minutes to neutralize. Next, electroless plating is started on the substrate surface to deposit palladium. This is, for example, a sensitizer (trade name: HS-101 manufactured by Hitachi Chemical Co., Ltd.) in a 15% HCl solution.
B) is mixed by 7% and immersed at room temperature for 10 minutes. Next, the glass substrate is immersed in a nickel plating solution, and nickel plating with an average film thickness of about 7000 Å is performed on the transparent electrode.

A metal film may be formed by electrolytic plating of aluminum. The effect of the present invention does not depend on the plating method. Electroless plating or electrolytic plating can be selected depending on the metal to be formed. .

By manufacturing as described above, fine irregularities can be formed on the surface of the metal film on the substrate. Actually, the average pitch is 1 to 2 μm and the depth is about 0.1 to 0.2 μm unevenness was successfully formed. In addition, using the substrate, a liquid crystal is sandwiched between a substrate facing the substrate via a seal portion, and a polarizing plate is provided on the outside of the substrate facing the substrate, and a liquid crystal using a nematic liquid crystal layer twist-aligned by 180 ° to 270 ° is used. When the display device was made, the background and the like were not reflected because the reflective layer was in a scattering state, and it was brighter and less shadowy than the conventional one in which a reflective plate was added to the outside of the substrate. A reflective liquid crystal display device having a viewing angle was obtained. In addition, since the electrode is made of metal, the electrode becomes a low-resistance electrode, the input voltage waveform is hardly rounded, and defects such as crosstalk that make the image non-uniform are greatly reduced.

As a result, for example, in a reflection type liquid crystal display device which is frequently used in a so-called notebook type personal computer or the like, a display which is easy to see, and which is thin, lightweight and consumes low power can be obtained.

The present invention is also applicable to a so-called black and white display type or color type liquid crystal display device having an optical compensator. A guest-host type using a dichroic dye that requires at most one polarizing plate, a DSM using light scattering, or a PSM in which a liquid crystal is dispersed in a polymer holder.
It is applicable to types such as DLC. Further, the present invention can be applied not only to the liquid crystal display device but also to various electro-optical devices.

[0042]

As described above, in the method of manufacturing an electro-optical device according to the present invention, a liquid crystal layer is sandwiched between a pair of glass substrates, and one of the glass substrates has a reflective layer on the liquid crystal layer side. In the method for manufacturing an optical device, a step of forming irregularities on the surface of the one glass substrate on the liquid crystal layer side, a step of applying an organic film on the irregularities of the glass substrate, and a reflective layer on the organic film Having a step of forming,
Since the surface of the reflective layer is made uneven by the unevenness of the surface of the one glass substrate spreading through the organic film, the reflective layer does not have a pinhole or the like, and the liquid crystal of the reflective layer Smooth irregularities can be formed on the surface on the layer side, and the light is scattered well by the reflective layer, so that the display is easy to see and the electro-optical device having a wide viewing angle can be easily manufactured. is there.

[0043]

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electro-optical device according to the present invention.

FIG. 2 is a perspective view of a substrate.

FIG. 3 is an explanatory diagram of a reflected light distribution.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 2, 3 Substrate 4 Liquid crystal layer 5 Electrode 6 Reflection layer (metal film) 7 Spacer 8 Polarizer

Continued on the front page (72) Inventor Hitoshi Nishizawa 3-3-5 Yamato, Suwa-shi, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Shuichi Imai 3-3-5, Yamato, Suwa-shi, Nagano Prefecture Seiko Epson Stock In-company (56) References JP-A-54-37697 (JP, A) JP-A-59-79280 (JP, A) JP-A-58-100174 (JP, A) JP-A-63-243916 (JP, A) JP-A-53-47298 (JP, A) JP-A-1-200329 (JP, A)

Claims (2)

(57) [Claims] 1. A method for manufacturing an electro-optical device having a liquid crystal layer sandwiched between a pair of glass substrates and having a reflective layer on a liquid crystal layer side of one of the glass substrates, wherein the liquid crystal layer of the one glass substrate is provided. Forming irregularities on the side surface; applying an organic film on the irregularities of the glass substrate;
And a step of forming a reflective layer on the organic film, wherein the unevenness on the surface of the one glass substrate spreads through the organic film, whereby the surface of the reflective layer becomes uneven. A method for manufacturing an optical device. 2. The method for manufacturing an electro-optical device according to claim 1, wherein the glass substrate is etched using hydrofluoric acid to form irregularities on the surface of the one glass substrate.