JPS6258218A - Thermo-writing liquid crystal light valve - Google Patents

Abstract

PURPOSE:To form a thermo-writing liquid crystal light valve which is high in displaying contrast and resolution, by shifting the 2nd light absorbing film from the 1st light absorbing film by one picture element. CONSTITUTION:The light absorbing film 5 of the light projecting side is constituted under a one-picture element shifted condition against the light absorbing film 8 formed on the writing light side. By providing a glass base plates and resin films having a smaller heat conductivity than the light absorbing films have and constituting the resin films and light absorbing films at every second picture element, escape of the heat produced in the light absorbing films in the direction of the base plate and in-plane direction is decreased and the produced heat is effectively used for raising the temperature of liquid crystal. Therefore, the scattering kernel is formed deeper and displaying contrast is improved. Moreover, picture elements of 10mum diameter are written and resolution is improved even if the diameter of a writing laser beam is expanded to 12mum, when, for example, the light absorbing films and resin films are formed at intervals of 10mum, because expansion of the heat in the in-plane direction is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a display device that utilizes the thermo-optic effect of liquid crystal, that is, a thermal writing liquid crystal light valve.

[Conventional technology and its problems]

By heating and rapidly cooling the liquid crystal, the random orientation state of the liquid crystal molecules is frozen, causing a phenomenon in which light is scattered. This is called the thermo-optic effect of liquid crystal. Taking advantage of this phenomenon, an image is written by irradiating a liquid crystal cell with a laser beam to cause a temperature rise in the irradiated area, and to erase the written image, an electric field is applied to the liquid crystal to force the liquid crystal molecules. There is a type of liquid crystal light valve that aligns the light. The laser light irradiated onto the liquid crystal cell is absorbed by the light absorption film and converted into heat. In a liquid crystal light valve, the liquid crystal layer transfers the heat generated by the light absorption film, causing a phase change to the liquid crystal (smectic phase → nematic phase → liquid phase), placing the liquid crystal molecules in a random state, and rapidly cooling them from the liquid phase to the smectic phase. This freezes the state (forms scattering nuclei), but the display contrast is improved if these scattering nuclei are formed over the entire thickness of the liquid crystal layer. Furthermore, the smaller the spread of heat generated in the light absorption film within the plane of the light absorption film, the higher the resolution and the better the display contrast.

Furthermore, the less the generated heat escapes toward the substrate, the deeper the scattering nuclei are formed and the display contrast is improved.

FIG. 4 shows a cross-sectional view of a conventional thermal writing liquid crystal light valve. A transparent type [i2. Light absorption film 4. A light reflecting film 3' and a liquid crystal aligning film 5 are sequentially formed. The written image is read out by the projection light and projected onto the screen, and on the inner surface of the substrate 11 on the projection light side, a transparent electrode 10° and a liquid crystal alignment film 7 are sequentially formed. These two substrates 1 and 11 are placed facing each other with spacers 13 and 14 interposed therebetween, the periphery is sealed with adhesive 15 and 16, and liquid crystal 12 is injected into the gap (Spring 1958, Japan Society of Applied Physics).

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However, in this conventional thermal writing liquid crystal light valve, when an image was written using a laser beam, a scattering pattern was not formed up to about half the thickness of the liquid crystal layer, and a sufficiently high display contrast could not be obtained. Further, even if the diameter of the writing laser beam is narrowed down to 10 μm, there is a drawback that the size of the pixel becomes 10 μm or more, resulting in a decrease in resolution due to the in-plane spread of heat when the temperature of the liquid crystal increases.

[Purpose of the invention]

An object of the present invention is to provide a thermal writing liquid crystal light valve with high display contrast and high resolution.

[Structure of the invention]

The thermal writing liquid crystal light valve of the present invention has two opposing first
and a liquid crystal is sandwiched between the second substrates, and a light absorption film and a resin film for absorbing the writing laser beam are formed every other pixel on the opposing surfaces of the first and second substrates, and The light absorbing film on the substrate is configured to be shifted by one pixel with respect to the light absorbing film formed on the first substrate.

[Function/principle of the invention]

The present invention forms a light absorption film and a resin film for every other pixel on opposing surfaces of first and second substrates that sandwich a liquid crystal, and forms a light absorption film and a resin film for every other pixel on the opposing surfaces of a first and second substrate that sandwich a liquid crystal, and Since the film is configured to be shifted by one pixel from the light absorption film formed on the first substrate, the escape of heat generated in the light absorption film in the in-plane direction is reduced, and the depth of scattering nucleus formation is reduced. Since the resolution increases, high resolution and high display contrast can be obtained.

[Embodiment] FIG. 1 is a sectional view showing the principle of the liquid crystal light valve of the present invention. A transparent electrode 2 is provided on the inner surface of the glass substrate 1 on the writing laser beam irradiation side. Cold mirror that transmits infrared rays and reflects visible light 3. Resin film 4. 5. A light-absorbing film made from an infrared-absorbing dye that has maximum absorption at the wavelength of a semiconductor laser. Liquid crystal alignment films 6 are sequentially formed. On the other hand, a transparent electrode 10 is provided on the inner surface of the glass substrate 11 on the projection light side. Resin film 9. 8. A light-absorbing film made from an infrared-absorbing dye that has maximum absorption at the wavelength of a semiconductor laser.
Liquid crystal alignment films 7 are sequentially formed. These two glass substrates 1
．． 11 are placed opposite to each other with spacers 13 and 14 interposed therebetween, their peripheries are sealed with an adhesive 15 and 16, and liquid crystal 1 or, for example, normal octyne cyano biphenyl is injected into the gap.

FIG. 2 shows the light absorption film and the resin film of the writing destination substrate as viewed from the projection light side. - The light absorption film on the power projection light side is configured to be offset by one pixel from the light absorption film formed on the writing photometer.

Note that the resin films 4 and 9 are patterned by, for example, coating a substrate with polyimide, then coating a photoresist, exposing it to light using a mask, and developing the photoresist.

By polyimide etching, photoresist stripping process, or by coating photosensitive polyimide onto the substrate,
This is done through a process of exposure using a mask and polyimide development. After forming the pattern, a light-absorbing film is formed by vapor-depositing an infrared-absorbing dye using a mask. Note that the light-absorbing film and polyimide film made from infrared-absorbing dyes are almost transparent to visible light, so they have no effect on the projected light.

By providing a glass substrate and a resin film having a lower thermal conductivity than the light absorption film, and configuring the resin film and the light absorption film every other pixel, the heat generated in the light absorption film is directed toward the substrate. In addition, since the escape in the in-plane direction is reduced and the generated heat is effectively used to raise the temperature of the liquid crystal, the scattering and nuclei are formed deeper and the display contrast is improved. Furthermore, in order to reduce the spread of heat in the in-plane direction, for example, the light absorption film and the resin film are
If it is formed every μm, the writing laser beam diameter will be 12 μm.
Even when the area is expanded to m, pixels with a diameter of 10 μm are written and the resolution is improved. In addition, a light absorption film and a resin film are formed every other pixel, and the light absorption film on the second substrate is shifted by one pixel with respect to the light absorption film formed on the first substrate. , when writing an image by absorbing laser light with the light absorption film on the first substrate, and writing to the next pixel by scanning the laser light, all of the laser light is absorbed by the light absorption film on the second substrate. and the image is written. As described above, in the present invention, the dot-shaped light absorption film formed on the first substrate,
An image is written by both dot-shaped light absorbing films formed on the second substrate.

Therefore, the spread of heat in the in-plane direction can be prevented, and an image with good resolution and contrast can be obtained.

In FIG. 1, the light absorption film 5 is embedded in a part of the resin film 4, but as shown in FIG.
Even if they are formed to have the same thickness, the in-plane spread of heat generated in the light absorbing film is reduced, resulting in improved resolution and further improved display contrast. Further, in FIG. 1, the coated mirror 3 is provided between the transparent electrode 2 for writing photometry and the resin film 4, but the resin film 4. Even if the cold mirror 3 is provided between the light absorption film 5 and the liquid crystal alignment film 6, there is no effect even if the liquid crystal light valve has a transmissive structure without the cold mirror 3.

〔Effect of the invention〕

As described above, according to the present invention, a thermal writing liquid crystal light valve with high display contrast and high resolution can be obtained.

[Brief explanation of drawings]

1 and 3 are cross-sectional views of the liquid crystal light valve of the present invention,
FIG. 2 is a view of the resin film and light absorption film on the writing substrate side as seen from the projection light side, and FIG. 4 is a sectional view of a liquid crystal light valve with a conventional structure. 1.11...Glass substrate, 2.10...Transparent electrode,
3...Cold mirror, 3'...Light reflecting film, 4.9
...Resin film, 5.8...Light absorption film, 6,7...Liquid crystal alignment film, 12...Liquid crystal, 13.14...Spacer, 15.16...Adhesive. Most / Figure 2 Figure 3 Porridge 4-Figure J0 Translucent Lake Pole, 7 Peng Oriented Xiao〃Substrate

Claims (1)

[Claims] A light absorption film and a resin film are formed on every other pixel on one surface of the first and second substrates, and the light absorption film and the resin film formed on these substrates are formed on each pixel of the first and second substrates. A thermal writing liquid crystal light valve characterized in that the substrates are arranged facing each other so as to be offset from each other, and the gap between the two substrates is filled with liquid crystal.