JPS6240430A - Liquid crystal light valve - Google Patents

Abstract

PURPOSE:To obtain the reflectance film which is easy to prepare and has a high reflectance property without dependence of an incidence angle by constituting the titled valve of two layer structures which composes of a reflectance film of a metallic film splited into minute parts, and a light absorption layer capable of absorbing a light transmitted through a gap of the first metallic film. CONSTITUTION:The reflectance film is composed of the metallic film 26 splited into the minute part and the light absorbing layer 27 capable of absorbing the light transmitted through the gap of the minute electrodes. The material of othe metallic film may be selected from Al, Ag and Au etc. The minute electrode is prepared according to a mask depositing method or a lithographic method. The size of the minute electrodes may be the vale less than an image solution value on the light valve. The gap of the minute electrode is prepared to <=5mum, preferably 2-3mum by the photolithography. A layer dyed an org. material layer with a black dyestuff is used as a simple example of the light absorbing layer. The light absorbing layer may attain the prescribed object by using a very high resistance material or an insulating material such as a layer made of a carbonaceous material or a silicon carbide in a wavelength range of a visiable or an incident light.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a liquid crystal light valve.

[Summary of the invention]

The present invention provides a liquid crystal light valve in which the light reflecting layer for projection has a two-metal structure, thereby simplifying the structure and making it easier to manufacture.

[Conventional technology]

FIG. 1 shows a conventional projection display system using a liquid crystal light valve. Transparent electrode 3 between glass plates 1 and 2
, 4, a semiconductor layer 6, and a liquid crystal layer 5 are formed. Appropriate between transparent electrodes 5 and 4? Apply an air bias and write the image you want to project with light from the right side using a laser or CRT. The semiconductor layer irradiated with light enters a low resistance state, and an electric bias is applied to the liquid crystal to excite the liquid crystal. On the other hand, the parts of the semiconductor layer that are not irradiated with light remain in a high resistance state,
No bias is applied to the liquid crystal. The amount of transmitted light of the liquid crystal layer 5 is modulated by applied voltage.

This principle is the same as that of a general liquid crystal display. Therefore, when the projection light is applied to the liquid crystal layer, it is reflected by the multilayer dielectric layer to form an image on the screen 10 by the writing light. As the reflective layer existing at the interface between the semiconductor layer 6 and the liquid crystal layer 5, a conductive film cannot be used in principle. However, since a high degree of reflection is required, the dielectric film is multilayered to ensure the necessary reflection.

[Problems and objects to be solved by the invention] This dielectric film is made of insulators with different refractive indexes, such as Sin, T, etc.
By stacking many layers of i□O8, an originally transparent film is formed as a reflective film.

For this reason, the method for forming this multilayer dielectric film is difficult, and furthermore, the incident angle of the projected light is limited.

Also, a small portion of the projected light inevitably leaks to the semiconductor layer side,
The semiconductor layer, which was originally only exposed to writing light, was irradiated with the light, degrading the image quality.

Therefore, an object of the present invention is to provide a reflective film that is easier to produce, has no dependence on the angle of incidence, and has high reflective ability.

[Means for solving problems]

The present invention is characterized by a two-layer structure including a metal film divided into minute shapes as a reflective film and a light absorption layer that absorbs light transmitted through the gap between the first metal layer.

[For production]

The reflective film according to the present invention is composed of a light absorption film and a metal film. Therefore, the reflectivity is approximately 100%, and almost no light is transmitted to the semiconductor layer.

At the same time, it can be reflected in a predetermined direction no matter what angle it is projected from.

〔Example〕

FIG. 2 shows an embodiment of the invention. glass plate 20.21,
The transparent electrodes 22 and 23 for bias application, the semiconductor layer 25, and the liquid crystal layer 24 are arranged in the same manner as in the conventional example. The reflective film is made up of a metal film 26 that is minutely divided and a light absorption layer 27 that absorbs the light that passes through the gaps between the minute electrodes.
The metal film may be made of any material such as AA, AP, and As. The microelectrodes are formed by mask vaporization method or photolithography. The size of this microelectrode on the light valve is
There is no problem as long as it is smaller than the resolution of the image.

For example, if 1000 x 1000 pixels are used on a light bulb with an effective area of 2 Cm x 3 (7H), the size of each pixel is 20 μm x 30 μm. In addition, the distance between the microelectrodes can easily be 5 μm or less by photolithography, and 2 to 5 μm.If the thickness of the metal film is 1 μm to 0.5 μm, it can be produced by vapor deposition or sputtering. However, when reducing the size of the microelectrode, especially to 10 μm or less,
The thickness of the metal film is preferably 0.2 μm or less. This is due to the requirement that the metal surface be as flat as possible in order to facilitate pattern formation and improve reflectivity.

- A simple example of the force absorbing layer is a method in which an organic layer is dyed with black dye. Further, a predetermined purpose can be achieved if the material or insulator has a very high resistance that absorbs visible light or incident light in the wavelength band. For example, a layer of carbon or silicon carbide.

FIG. 3 is an enlarged view of the invention. After depositing transparent M, three poles, and semiconductor layers such as Od-S e and A-S i on the glass substrate 30, an organic film such as gelatin is applied and dyed by immersing it in a black dye solution. . Then A2
Alternatively, A2 is deposited to a thickness of 0.2 μm and a microelectrode is formed by photolithography. After that, a facing glass is placed and the surrounding area is sealed, and liquid crystal is injected to obtain a liquid crystal light valve.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a light valve that is independent of the incident angle and that does not deteriorate image quality due to light leaking into the semiconductor layer. Moreover, the most important effect is that production is extremely simple and easy. Conventionally, around 10 layers of different materials were used, but now only two layers are needed. As a result, the performance of the projection display device can be improved, and the system can be made more compact and cost-effective.

[Brief explanation of drawings]

Figure 1 is a structural diagram of a conventional liquid crystal light valve. FIG. 2 is a structural diagram of the liquid crystal light valve of the present invention. FIG. 6 is a partial view of the liquid crystal light valve of the present invention, (cL
) is an enlarged sectional view, and (b) is an enlarged plan view. 1.2.20.21.30...Glass plate 3.4, 22
, 23.31...Transparent electrode 6.25.32...Semiconductor layer 5.24...Liquid crystal layer 10...Screen 7...Multilayer dielectric film 26.33...Reflective metal film 27. 34...Light absorption layer or above

Claims (1)

[Claims] (1) In a liquid crystal light valve that includes two glass plates, transparent electrodes on each glass plate, and a semiconductor layer and a liquid crystal layer sandwiched between the transparent electrodes, a microelectrode is formed at the interface between the semiconductor layer and the liquid crystal layer. A liquid crystal light valve characterized by having a metal film and a light absorption layer.