JP3274276B2 - Photoconductive liquid crystal light valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a photoconductive liquid crystal light valve (hereinafter, referred to as LCLV) for reflecting a light beam while giving a projected image, and projects the reflected light by a projection lens system. The present invention relates to a projection display device.

[0002]

2. Description of the Related Art FIG. 1 shows the structure of an LCLV1.
The liquid crystal layer 11 includes a spacer 12 and an alignment film 1 around the liquid crystal layer 11.
3, 14. The photoconductive film 15 on which an image is drawn is a reflective film 16 (dielectric mirror) made of a dielectric.
And a light-shielding film 17 interposed therebetween on the alignment film 14 side. A transparent electrode 18 is disposed on the read side surface of the alignment film 13, and an electrode 19 is disposed on the write side surface of the photoconductive film 15. The liquid crystal layer 11, the photoconductive film 15, and the like are sandwiched between a pair of glass substrates 20, 21.

In an LCLV1 in which an AC voltage is applied between the transparent electrodes 18 and 19, when an image is drawn on the photoconductive film 15 by CRT from an image writing light incident from the right side (writing side) in the drawing, the photoconductive film Since the internal resistance of the liquid crystal layer 15 changes locally to become lower or higher in accordance with the brightness of the image (change in the amount of received light), the inside of the adjacent liquid crystal layer 11 corresponding to the changed portion of the photoconductive film is made of transparent electrodes 18 and 19. When an alternating voltage is applied between the two, the liquid crystal molecules are spatially modulated according to the brightness of the image, and a birefringence is generated.

As shown in FIG. 2, the photoconductive film side substrate of the LCLV 1 of such a projection type liquid crystal display device is connected to the front face of the CRT 2. The CRT writes the image displayed on the front face to the photoconductive film of the LCLV1 via the fiber optical plate. The density of the projected image on the liquid crystal layer is formed according to the potential of the photoconductive film. On the other hand, a light flux emitted from the light source 3 such as a metal halide lamp as a substantially parallel light beam by the reflector enters the polarization beam splitter 6 via an optical element such as a polarizing plate. The P-polarized light component of the incident light passes through the polarization beam splitter 6. The traveling direction of the S-polarized light component is bent by the polarization beam splitter 6, and is incident on the LCLV1.

Here, if a birefringence corresponding to the image of the CRT is generated in the liquid crystal layer of the LCLV1, if the reflected light reflected by the LCLV has a birefringence in accordance with the birefringence of the liquid crystal layer.
The polarization component is converted to a P polarization component. Then, the P-polarized light component passes through the polarizing beam splitter 6 as it is, so that the P-polarized light component, that is, the projection light is projected onto the screen 9 via the projection lens 8.

[0006]

The light-shielding film, which is a black thin film, has a light-shielding property that does not allow strong projection light from a light source to enter the photoconductive film, and a high impedance that does not widen the voltage distribution and reduce the resolution. Absolute value is required. However, it is difficult to obtain a single-layer light-shielding film made of a single substance that satisfies both these characteristics. Even if a light-shielding film is formed by mixing a plurality of light-absorbing substances, the film thickness must be set in accordance with the amount of light absorbed by a substance having a small amount of light absorption in a predetermined spectrum, that is, a light-absorbing substance having a weak light absorption spectrum. And the film thickness was more than necessary. If the thickness of the light-shielding film is larger than necessary, a sufficient change width of the LCLV liquid crystal layer impedance cannot be obtained.

An object of the present invention is to provide an LCLV having a light-shielding film which has a high impedance and a high light-shielding property, and which can select a light wavelength to be cut off.

[0008]

The LCLV of the present invention comprises a pair of opposing write-side and read-side transparent substrates, and a pair of opposing write-side and read-side transparent substrates laminated on the respective inner surfaces of the transparent substrates. An electrode and a conductive liquid crystal light valve in which a photoconductive film, a light shielding film, a reflective film, and a liquid crystal layer are sequentially arranged from the writing side transparent electrode between the transparent electrodes, wherein the light shielding film is formed of a light absorbing material. And the light-absorbing substances have different light absorption spectrum distributions from each other.

[0009]

According to the present invention, a light-shielding film which is a multilayer black insulating film capable of selecting a light wavelength to be cut off is provided, so that a high resolution LCLV can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows this embodiment. The LCLV 1 is a multilayer black insulating film 117 composed of a plurality of, for example, three, thin films 17a, 17b, 17c each containing a light absorbing material, and the light absorbing material distribution of the multilayer black insulating film, ie, the light shielding film, is different from each other. Except that it has the same structure as the LCLV shown in FIG. 3 has the same structure as the CRT shown in FIG. 2 except that the writing-side glass substrate is a substrate 21a made of a fiber optical plate and the CRT 2 is a substrate 2a made of a fiber optical plate. . The fiber optical plates of the LCLV and the CRT are joined by a joining layer 30 made of silicon gel, glycerin or the like.

The first layer 17a and the second layer 17 of the light shielding film 117
b and the third layer 17c are thin films made of nickel (Ni), cobalt (Co) and vanadium (V) having different light absorption spectrum distributions, respectively, and have a thickness of 500 nm or less, 600 nm to 700 nm and 700 nm, respectively. ~ 90
It is formed in a range of 0 nm. More preferably, each of the first layer 17a, the second layer 17b, and the third layer 17c may be mixed with silicon dioxide (SiO ₂ ) to form a multilayer black thin film in which each is dispersed. Ni, Co and
In addition to V, manganese (Mn) can also be used as a light absorbing material of the light shielding film. That is, by combining the thin films of these light absorbing substances, the range of selection of the light wavelength to be cut off can be expanded by superimposing the light absorption spectrum. Furthermore, SiO ₂
Can increase the absolute value of the impedance of the light-shielding film. FIGS. 4, 5, 6, and 7 show the light absorption spectrum distribution characteristics of a single layer of the SiO ₂ mixture thin film of the light absorbing substances Ni, Co, V, and Mn.

As a method for manufacturing the light shielding film 117, an RF or DC sputtering method or an EB vapor deposition method can be used.
The thickness ratio of each thin film is appropriately set. For example, FIG. 8 shows a light absorption spectrum distribution characteristic of a mixture multilayer light-shielding film specifically formed of a first layer Ni, a second layer Co, and a third layer V by adding SiO ₂ to each. In this case, the thickness ratio of the Ni layer, the Co layer, and the V layer is Ni: Co: V = 1: 1: 1. Further, as shown in FIG. 9, the film thickness ratio Ni: V = 3:
Even in the case of the two-layer type light-shielding film containing SiO _{2 of the} first Ni layer and the V layer, the wavelength is about 40 times larger than that of the single Ni layer (FIG. 4).
A sharp absorption characteristic near 0 nm is obtained.

[0013]

As described above, according to the present invention, a pair of opposing write-side and read-side transparent substrates, and a pair of opposing write-side and read-side transparent electrodes laminated on each inner surface of the transparent substrate are provided. A conductive liquid crystal light valve in which a photoconductive film, a light-shielding film, a reflective film, and a liquid crystal layer are sequentially arranged from a writing-side transparent electrode between transparent electrodes, wherein the light-shielding film includes a plurality of thin films each containing a light-absorbing substance. And the light absorbing substances have different light absorption spectrum distributions from each other, so that an LCLV with high resolution capable of selecting a light wavelength to be blocked can be obtained.

[Brief description of the drawings]

FIG. 1 is a structural diagram schematically showing an LCLV.

FIG. 2 is a structural diagram schematically showing a projection display device using an LCLV.

FIG. 3 is a structural diagram schematically showing an LCLV of an example.

FIG. 4 is a graph of light absorption spectrum distribution characteristics showing a relationship between an incident wavelength and a light absorption coefficient.

FIG. 5 is a graph of light absorption spectrum distribution characteristics showing a relationship between an incident wavelength and a light absorption coefficient.

FIG. 6 is a graph of light absorption spectrum distribution characteristics showing a relationship between an incident wavelength and a light absorption coefficient.

FIG. 7 is a graph of a light absorption spectrum distribution characteristic showing a relationship between an incident wavelength and a light absorption coefficient.

FIG. 8 is a graph of light absorption spectrum distribution characteristics showing a relationship between an incident wavelength and a light absorption coefficient in the present embodiment.

FIG. 9 is a graph of light absorption spectrum distribution characteristics showing a relationship between an incident wavelength and a light absorption coefficient in the present embodiment.

[Explanation of Signs of Main Parts]

 DESCRIPTION OF SYMBOLS 11 Liquid crystal layer 12 Spacer 13, 14 Alignment film 15 Photoconductive film 16 Reflection film (dielectric mirror) 117 Dispersion film (light shielding film) 18, 19 Transparent electrode 20, 21 Glass substrate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/135 G02F 1/1335 500

Claims (2)

(57) [Claims] 1. A pair of opposing write-side and read-side transparent substrates, a pair of opposing write-side and read-side transparent electrodes laminated on inner surfaces of each of the transparent substrates, and the writing between the transparent electrodes. A conductive liquid crystal light valve in which a photoconductive film, a light-shielding film, a reflective film, and a liquid crystal layer are sequentially arranged from a side transparent electrode, wherein the light-shielding film includes a plurality of thin films each containing a light-absorbing substance. A photoconductive liquid crystal light valve, wherein the absorbing substances have different light absorption spectrum distributions. 2. A photoconductive liquid crystal light valve according to claim 1, wherein each of said light shielding films is made of a mixture of said light absorbing substance and silicon dioxide dispersed in each other.