JPS6286330A - Color thermal writing liquid crystal light valve - Google Patents

Abstract

PURPOSE:To provide a high saturation color display which prevents color mixing by forming the titled valve in such a manner that the clock signal for controlling a writing position can be always obtd. from a filter of the specific color based on the position regardless of the quantity of writing light. CONSTITUTION:Only the diffraction grating of the green color filter 42 is so formed that the direction of grooves 35 thereof is different from the directions of the grooves 44, 46 of the diffraction gratings of the other red and blue color filters 41, 43. Three colors; bluish green, purple and yellow or 4 colors; bluish green, purple, yellow and red are also possible in addition the three colors; and green and blue with the multicolor filters. The diffraction gratings of one or two color filters among the same may be so formed as to have the groove direction different from the groove direction of the other diffraction gratings in order to obtain the signal based on the position.

Description

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

[Conventional technology]

BACKGROUND ART In recent years, there has been a demand for displays that are highly accurate and can be partially rewritten in computer-based image processing, newspaper editing, and LSI (Z) design.

As a display device with a high resolution of 2000 lines or more, there is a display that thermally writes with liquid crystal laser light.
Proceedings of the Varnish Eye Day (Pr.
oceecHng of the 8, T.

D,)j Paper published in 1978, pages 1-7 [Laser Selective Liquid Crystal Projection Display (LACE-A]) D几E8SED LIQID CRYS'l'AL
PROJEC'rION DISPLAY) J.

According to this paper, an image can be recorded on a liquid crystal light valve 29 as shown in FIG. 5 by scanning with a laser beam 20, and the image can be displayed by reflecting the incident light 21. The liquid crystal light valve 29 has a light absorption film 23.
Aluminum reflective film 24°, liquid crystal alignment film 28 formed/glass substrate 22, transparent electrode film 26. It has a structure in which a liquid crystal material 25 is sandwiched between a glass substrate 27 on which a liquid crystal alignment film 28 is formed. When the laser beam 20 enters the liquid crystal light valve 29, the laser beam 20 is absorbed by the light absorption film 23 and converted into heat, and the aluminum reflection film 24. The temperature of the liquid crystal material 25 is increased through the liquid crystal alignment film 28. Smectic liquid crystal is used as the liquid crystal material 25, and the smectic liquid crystal changes into a nematic phase and a liquid phase by increasing the temperature.
When the laser beam 20 is removed, the liquid crystal molecules are rapidly cooled to freeze the random orientation of the liquid crystal molecules, and the scattering plate is read out by the projection light 21 and displayed as pixels on the screen.

Since the thermal writing liquid crystal display uses scattering and non-scattering of the liquid crystal for display, the 5 display is a black and white pattern. A method of producing a color display of at least three colors is described in the specification of ``Color thermal writing liquid crystal projection type disk T/I and writing method therefor'' in Japanese Patent Application No. 60-121036. According to the above invention, the liquid crystal light valve includes:
It has a built-in three-color stripe color filter in which three types of color filters, each consisting of a diffraction grating that gives an optical phase difference so as to diffract visible light in a specific wavelength range in the zero-order direction, are arranged periodically within the plane. , the above color filter is
It can be formed into very fine widths and has excellent light and heat resistance. In addition, the laser beam is scanned with an amount of light below the threshold that enters the liquid crystal light valve.1. eye,
When the first-order diffracted light that is reflected and diffracted from the diffraction grating in the liquid crystal light valve is received, the first-order diffracted light is different from the scanning position of the laser beam and the color because the diffraction efficiency of the diffraction gratings corresponding to the three types of H-Lar filters is different. It receives intensity modulation in one-to-one correspondence with the position of the filter, and extracts the signal from a specific color filter that is used as a position reference from the electrical signal obtained from the receiver, and writes it as a position reference clock. Assuming a signal, writing to each color filter position is done by setting an appropriate delay time from the position reference clock signal and giving the laser beam a sufficient amount of light to write to the liquid crystal light valve. It will help you understand.

[Problem that the invention seeks to solve]

However, the electrical signal obtained by receiving the first-order diffracted light which has been intensity-modulated at 1 in one-to-one correspondence with the position of the color filter (the electrical signal obtained at 1 has a smaller modulation amplitude than shown in FIG. 4 (2), and In order to always extract a signal from a filter of a specific color regardless of changes in the amount of writing light, a gate circuit is required, making signal processing complicated.

An object of the present invention is to be able to separate and receive the first-order diffracted light from a specific color filter and the first-order diffracted light from other color filters, and to be able to receive the first-order diffracted light from a specific color filter without using a gate circuit, regardless of changes in the amount of 1" light. Another object of the present invention is to provide a color thermal writing liquid crystal light valve that can obtain a position-based clock signal with a large modulation amplitude and facilitates signal processing for controlling the writing position.

[Means for solving problems]

51 The color thermal writing liquid crystal light valve of the present invention comprises a transparent substrate, an X-absorbing film, a light reflecting film, a liquid crystal alignment film, a liquid crystal,
It consists of a liquid crystal alignment film, a transparent electrode film, and a transparent base layered one after another, and consists of a diffraction grating that provides an optical phase difference between the above components so as to diffract visible light in a specific wavelength range. A multi-color filter is formed in which at least two types of color filters are arranged periodically within the plane.
In the color thermal writing liquid crystal light valve, the groove direction of at least one of the diffraction gratings of the multicolor filter is formed to be different from the groove direction of the other diffraction gratings.

[Principle and operation of the invention]

A multi-color filter, in which at least two types of color filters consisting of diffraction gratings with optical phase differences are arranged periodically within a plane, diffracts only the visible light in a specific wavelength range of the projected light, and displays the color on the projection screen. In addition to having the function of displaying, it also performs scanning with a light intensity of 2° below the threshold of directing the laser beam into the liquid crystal light valve. By receiving the diffracted light,
By knowing the mutual positional relationship between the color filter and the writing light, writing can be performed with high positional accuracy. Here, if the groove direction of at least one type of diffraction grating used as a position reference among the diffraction gratings of the multicolor filter is formed to be different from the groove direction of the other diffraction gratings, the writing laser beam can be directed to the liquid crystal light pulp. In the case of scanning 1- with the light intensity below the smearing threshold, the diffracted light from the diffraction grating used as a position reference is diffracted in a different direction because the groove direction is different from that of other diffraction gratings.
! The electric signal obtained by receiving the light has a larger amplitude than the conventional example, and the signal from the filter of a specific color is always used as a position reference regardless of changes in the amount of light. is obtained. Therefore, if this electric signal is used as the position-based clock signal for writing, writing to the position of each color filter is performed by setting a suitable delay time from the position-based clock signal and writing to the liquid crystal light pulp using laser light. By providing a sufficient amount of light to each pixel, it becomes possible to write each pixel with high positional accuracy.

FIG. 6 is a diagram showing the principle of a color filter using a diffraction grating used in the present invention. In FIG. 6, there is a reflective diffraction grating coated with a reflective film 31 on the surface of a substrate 300 having rectangular irregularities of depth d, and a white light 32
When it is incident, mainly the 0th new party 33. +1st order diffraction 934
．． -1st order diffracted light 35 is diffracted. →-1st order diffracted light 34
, -1st order diffracted light 35 is diffracted in different directions depending on the wavelength, and the diffraction direction depends on the pitch of the diffraction grating.

The zero-order new party 330 wavelength distribution returning to the specular reflection direction depends on the depth d.

The O-th order intensity η of an arbitrary wavelength λ can be obtained by the following equation, where n is the refractive index of the medium through which the light travels.

3=cos” (2πnd/λ) ---
---(1) Equation (1) has a maximum value of 1 when the depth d of the grating satisfies the following expression.

d=mλ/2n (m is an integer) (2)
Further, the minimum value is 0 when the depth d of the grating satisfies the following equation.

d=(2m+1)λ/4n (mF!, integer)−(
3) In Figure 7, the refractive index n of the liquid crystal is 15°, and the depth d of the diffraction grating is (a) 290 nm, (b) 5
The wavelength distribution of the O-th new party at 20 nm l (C) 24 o nm is shown. The colors for each case are (a) blue, (
b) green and (C) red are obtained.

〔Example〕

FIG. 2 is a diagram showing an embodiment of a multicolor filter used in a color thermal writing liquid crystal light pulp according to the present invention. Multi-color filter: 41 red, 42 green. blue 43
When the refractive index of the liquid crystal is 1.5, the depth of the diffraction grating is 290 nm for each of the three colors.

520nm, 290nm, lattice constant of diffraction grating 2
/jm, and one pixel is formed with a size of 10 μm×30 μm. Therefore, on a 30mm square glass base, red,
Green and blue filters can each have 100OX1000 pixels. However, the lattice constant of the diffraction grating does not have to be as large as 3'PM.

To imprint the diffraction grating shown in Figure 2 on a glass substrate, first, the diffraction grating of one type of color filter is formed on the glass substrate masked with photoresist by chemical etching, ion milling, etc. By changing the depth and repeating the process twice, a diffraction grating of a three-color color filter may be formed. In addition, a similar multi-color filter can be obtained by forming a diffraction grating using a photosensitive resin butter 2/g, or by taking a replica and transferring it to a plastic resin.

The refractive index of the glass substrate is 1.47. When the wavelength of the homokomi laser beam is 0.83 μm, the first-order light diffraction efficiency of the diffraction gratings corresponding to red, green, and blue color filters is 8.3, respectively.
%, 9.2chi, 03%, it is appropriate to use the first-order diffracted light from red or green to receive the first-order diffracted light and obtain the reference signal grain at the complimentary position. In the figure, only the direction of the grooves 35 of the diffraction grating of the green color filter 42 is formed to be different from the direction of n44°46 of the diffraction gratings of the other red and blue color filters 41 and 43. In addition to the three colors of red, green, and blue, multicolor filters are also available with three colors of blue-green, purple, and yellow, or four colors of blue-green, purple, yellow, and red. In order to obtain a signal, the groove direction of the diffraction grating of one or two color filters may be formed to be different from the groove direction of the other diffraction gratings.

FIG. 1 is a perspective view of one embodiment of a color thermal writing liquid crystal light valve according to the present invention. In contrast to the liquid crystal light valve shown in FIG. 5, the color thermal writing liquid crystal light valve 1 has a diffraction grating 5 shown in FIG.
It is different in that it is engraved. A ■-■ group compound semiconductor film containing Cd, a ■-■ group compound semiconductor film containing Te, and an absorption dielectric length interference film are formed on a glass substrate 4 as a light absorption film 6 by vapor deposition. An AI film is deposited as the film 7, and a polymer film or an 8i0 film is formed as the liquid crystal alignment film 8 on it.・An oxide) film is attached, and a liquid crystal alignment film 8 is further formed.

As the liquid crystal 9, a smectic liquid crystal such as 0CBP (octyl cyan biphenyl), DCBP (tethylucyano biphenyl), or a mixture thereof can be used.

The color thermosetting liquid crystal light valve 1 constructed in this manner is irradiated with laser light 2 in the same manner as in the prior art. For example, when using red, green, and blue color filters for color image generation,
To obtain a red image, write with a laser beam on the liquid crystal area corresponding to the green and blue color filters. To obtain green and blue images, similarly, laser light is applied to the liquid crystal parts corresponding to the red and blue and red and green color filters. Yellow, purple, and blue-green are obtained by additive color mixing. Furthermore, by controlling the amount of laser light for writing and providing gradation, full-color images can be realized.

Regardless of the nonlinearity of the optical scanning writing optical system, in order to select the position of each color filter and irradiate the laser beam 2 to penetrate the liquid crystal, it is necessary to know the positional relationship between the laser beam 2 and each color filter. There is a mandatory withdrawal.

For this purpose, during the horizontal scanning period by the laser beam deflector 3, the liquid crystal light valve 1 is scanned with a constant amount of light below the threshold value. When the laser beam 2 scans the diffraction gratings corresponding to the red and blue filters, +1st-order diffracted light 12. shown by the broken line. The −1st-order diffracted light 13 is reflected and diffracted [~, scanning the diffraction grating corresponding to the green filter (~), the +1st-order diffracted light 14 and −-order diffracted light 15 are reflected and diffracted as shown by dotted lines.

In this way, the ±1st-order diffracted light 14.15 from the diffraction grating corresponding to the green filter is the other ±1st-order diffracted light 12°13.
The diffraction directions are different, and the light can be received separately by the light receiver 16. However, it is only necessary to receive at least one of the ±1st-order diffraction lights 14 and 15. The electrical signal obtained from the light emitter is only obtained when the laser beam 2 scans the green color filter used as the position reference. Therefore, this can be used as a position-based clock signal. When writing to the position of each color filter, when there are red, green, and blue image signals, set an appropriate delay time from the position-based clock signal, and write to the laser light enough to write to the liquid crystal light valve. This is done by providing the amount of light.

FIG. 3 is a diagram showing an example of an electrical signal obtained by receiving first-order diffracted light. Compared to the conventional example shown in FIG. 4, it is possible to obtain a writing position control clock signal with a large fluctuation amplitude regardless of changes in the 1:input light sound without using a gate circuit.

〔Effect of the invention〕

As described in detail above, in this invention, the clock signal for writing position control can always be obtained from a filter of a specific color with the position reference regardless of changes in the amount of irradiation light, so each pixel can be colored with high precision. It is written at the position of the filter and has the effect of making it possible to display high-saturation color while preventing color mixture.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a color thermal writing liquid crystal light valve according to the present invention, FIG. 2 is a diagram showing an embodiment of a multicolor filter used in the color thermal writing liquid crystal light valve according to the present invention, and FIG. 4 is a diagram showing a conventional optical receiver signal, FIG. 5 is a cross-sectional view of a conventional liquid crystal light valve, and FIGS. 6 and 7 are diagrams showing a conventional liquid crystal light valve. FIG. 2 is a diagram illustrating the principle of wavelength selection of a diffraction grating used in the present invention. ■・・・Color thermal writing liquid crystal light bulb, 2・
...Laser light, 3...Light deflector, 4...
...Glass base. 5...Diffraction grating, 6...Light absorption film, 7
...Reflection film, 8...Liquid crystal alignment film, 9.
...Liquid crystal, 10...Transparent electrode film, 11.
...Glass base, 12...+1st-order diffraction source, 13...--1st-order diffracted light, 14...+
1st-order diffracted light, 15...--1st-order diffracted light, 16...
・・・・Receiver, 17・・・・Sokon lens. Fig. 2 Fig. 3 Fig. Fig. 4 Fig.

Claims (1)

[Claims] A transparent substrate, a light absorption film, a light reflection film, a liquid crystal alignment film,
A diffraction device that is composed of a liquid crystal, a liquid crystal alignment film, a transparent electrode film, and a transparent base layered one after another, and an optical phase difference is provided between the above components so as to diffract visible light in a specific wavelength range. In a color thermal writing liquid crystal light valve in which a multi-color filter is formed in which at least two types of color filters consisting of gratings are periodically arranged in a plane, at least one type of diffraction grating among the diffraction gratings of the multi-color filter. A color thermal writing liquid crystal light valve characterized in that the groove direction of the diffraction grating is formed to be different from the groove direction of other diffraction gratings.