JPS61223720A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To write an image of high resolution in a liquid crystal plate by providing a reflecting plate in the liquid crystal plate and correcting a focusing lens so that the focus of write laser beam coincides with the reflecting plate at any time. CONSTITUTION:The reflecting plate 3 is interposed behind the beam absorbing film 2 of the liquid-crystal plate 1 and the focusing lens 8 which stops down the write laser beam is provided so that its focus is corrected by a driving coil 11. In this constitution, the write laser beam from a laser oscillator 5 is absorbed by the beam absorbing film 2 by a specific quantity to perform writing operation. Then, transmitted beam is reflected by the reflecting plate 3 and photodetected by a photodetecting plate 9 and the focus of the focusing lens 8 is corrected so that the focus of the laser beam coincides with the reflecting plate 3 at any time. Consequently, an image of high resolution is written in the liquid crystal plate 1 and projected on a screen 15 by the irradiation of a beam source 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] The present invention relates to a liquid crystal display device that records and projects images on a liquid crystal plate by utilizing the thermo-optic effect of liquid crystal.

[Background of the Invention 1 An example of the structure of a conventional thermal writing liquid crystal plate is shown in FIG. 2
0 is a liquid crystal plate, 21 is a liquid crystal layer, 22.23 is an alignment film, 24
．． 25 is a transparent electrode, one of which also serves as a heating electrode;
6 is a total reflection plate, 27 is a light absorption film that absorbs the total amount of heat of the writing laser beam 30, and 28 and 29 are transparent base materials. still,
For the sake of explanation, it is assumed that the direction in which the writing laser beam 30 is incident on the transparent substrate 28 is the writing direction, the direction in which the projection light 31 is incident on the transparent substrate 29 is the output direction, and the transparent electrode 25 also serves as a heating electrode.

The writing laser beam 30 is incident from the writing direction to the transparent substrate 28. When the light passes through the transparent electrode 1fi24 and reaches the light absorbing WA27, the light absorbing film 27 absorbs the heat and cooling of the portion irradiated with the writing laser light 30.

The heat absorbed by the light absorption film 27 is transmitted to the liquid crystal layer 21 through the reflection plate 26 and the alignment film 22, as shown in FIG. 3(a).
As shown in FIG. 3, the cell temperature of the liquid crystal layer 21 rises to an isotropic liquid phase (I phase) while the writing laser beam 30 is ON, and then changes to a nematic phase (N phase) when the writing laser beam 30 is turned OFF. By rapidly cooling the liquid crystal layer 21 to a smectic phase (S phase), the liquid crystal layer 21 changes from a transparent state to a light scattering state in which a focal conic structure is formed, and an image is written in a positive state.

Furthermore, when voltage V1 is applied to the transparent electrode 25 as a heating electrode and then the voltage is gradually lowered, the cell temperature, which has risen to phase 1 due to voltage V1, is slowly cooled to phase S. As a result, 2) a homeotropic structure is formed within the liquid crystal layer 21, and the entire liquid crystal layer 21 becomes transparent. The liquid crystal plate on which an image has been written with the writing laser beam 30 in this manner is exposed to the projection light 31 from the display light source from the output direction, and the transparent substrate 29. Transparent electrode 25. The projection light 31 that has passed through the alignment film 23° and the liquid crystal layer 21 further passes through the alignment film 22 and is reflected by the reflection plate 26 to project the image written on the liquid crystal layer 21.

FIG. 4 is a diagram showing an example of a conventional enlarged projection type liquid crystal display device. 32 is a laser oscillator, 33 is a deflector such as a rotating polygon mirror, 34 is an imaging lens such as an fθ lens, 35 is a deflection prism or half mirror, 136 is a lens, 37 is a display light source, 38 is a magnifying lens, and 39 is a display It is a screen for

A laser beam from a laser oscillator 32 is modulated by an optical modulator (not shown), deflected by a deflector 33, and an image is written on the liquid crystal plate 20 via an imaging lens 34. The written image on the liquid crystal plate is projected by the projection light from the display light source 37 that has passed through the lens 36° deflection prism or half mirror 35.

The projection light reflected by the liquid crystal plate 20 is reflected by a deflection prism or half mirror 35, magnified by a magnifying lens 38, and projected onto a display screen 39 in an enlarged manner.

[Problems with Background Art] Generally, the beam diameter d and depth of focus of a writing laser beam are expressed by the following equation.

d, = λ/NA... (1) h-=l/
(NA)2・・・・・・■ (However, NA is the numerical aperture of the lens.2) From formula (1), the beam diameter d can be determined by narrowing down the beam diameter by using a lens with a large numerical aperture NA. becomes smaller. Therefore, high resolution images can be written.

However, according to formula (①), as the numerical aperture NA increases, the depth of focus becomes shallow2), and a small error in the focal length -
I lose focus. Therefore, when a lens with a large numerical aperture NA is used, focus correction of the writing laser beam must be performed sequentially.

The conventional liquid crystal display device as described above uses an imaging lens with a small numerical aperture NA, and therefore has a long depth of focus.

Therefore, the beam diameter d(
Changes in the beam diameter d (approximately 10 to 20 μm) of conventional liquid crystal display devices could be tolerated. However, the beam diameter d
If an imaging lens with a large numerical aperture NA is used in order to reduce It is difficult to drive the imaging lens to correct the focal length2), and the apparatus becomes large.

Further, as a method of detecting the focal length, there is a method of using a writing laser beam reflected by a liquid crystal plate, but in the structure of a liquid crystal plate in a conventional liquid crystal display device, all of the writing laser beam is applied to the light absorption film 27. The reflected light cannot be detected because it is absorbed.

Furthermore, due to problems with the accuracy of the optical system, it is desirable that the deflector 33 and the imaging lens 34 be fixed in the writing direction of the liquid crystal plate 20. Therefore, in order to project and display the image recorded on the liquid crystal plate 20, In this case, the projection light must be projected from the output direction of the liquid crystal plate 20, and the display must be performed using the projection light reflected by the liquid crystal plate 20. For this purpose, an optical system such as a deflection prism or a half mirror is required to project the projection light reflected by the liquid crystal plate onto the display screen 39, and a height is required to clearly display the image recorded on the liquid crystal plate 20. A light source for displaying brightness was required. In conventional liquid crystal display devices, writing a high-resolution image by narrowing down the beam diameter has the problem of making the device complicated, large, and expensive2). .

[Object of the Invention] An object of the present invention is to provide a liquid crystal display device that is capable of writing high-resolution images on a liquid crystal plate.

[Summary of the Invention] The present invention comprises at least a liquid crystal layer, a pair of alignment films sandwiching the liquid crystal layer, a transparent electrode, and a transparent base material, and between one of the transparent electrodes and the transparent base material, there is a A liquid crystal plate that includes a light absorption film that absorbs light for a predetermined period of time and conducts the absorbed heat to the liquid crystal layer, and a reflection plate that reflects light of a predetermined wavelength that has passed through the front light distribution absorption film in the direction of incidence. ; a laser oscillator that emits light of a predetermined wavelength; a focusing lens that narrows down the beam diameter of the light of the predetermined wavelength; a light receiving element that detects reflected light from the liquid crystal plate; and a light receiving signal of the light receiving element that controls the focusing lens. a writing optical head that scans the liquid crystal plate and writes an image; and a writing optical head that writes an image by scanning the liquid crystal plate; The first feature is a projection optical system that projects an image recorded on the liquid crystal plate using transmitted light transmitted through the liquid crystal plate; It consists of a liquid crystal layer mixed with a dye that absorbs only light, a pair of alignment films sandwiching the liquid crystal layer, a transparent electrode, and a transparent base material, and reflects light of a predetermined wavelength between one of the transparent electrodes and the transparent base material. The second feature is that the writing optical head 2) writes binary data on the liquid crystal plate. A fourth aspect of the present invention provides a liquid crystal display device comprising: a decoder for projecting projection light onto a liquid crystal plate containing a liquid crystal panel and decoding the binary data based on transmitted light or reflected light of the liquid crystal plate. .

Tip 2): The beam diameter of the writing laser beam is reduced using a focusing lens, and the focal length is detected by the reflected light of the writing laser beam from a reflection plate with wavelength selection characteristics provided within the liquid crystal plate, and the focal length deviation is detected. An image is written on a liquid crystal plate using a writing optical head that corrects the focus by driving the focusing lens against the image, and then a projection light having a wavelength different from that of the writing laser beam is projected from the writing direction of the writing optical head. By doing this, 2) the image written on the liquid crystal plate is projected by the projection light that has passed through the reflection plate in the liquid crystal plate.

[Embodiment of the Invention] An embodiment of the present invention will be described with reference to FIGS. 1 and 5. FIG. 1 is a diagram for explaining image writing and display on a liquid crystal display device according to the present invention, and FIG. 5 is a diagram showing an example of the configuration of the liquid crystal display device according to the present invention. For example, Figure 1 (a
), 1 is a liquid crystal plate 2), and the same parts as in FIG. 2 are designated by the same reference numerals. The liquid crystal plate 1 according to the present invention absorbs a predetermined amount of light of a specific wavelength (writing laser light incident from the writing optical head 4 described in I) between a transparent electrode 25 and a transparent base material 29 as shown in the figure. Absorption film 2 and light absorption II! A reflecting plate 3 is inserted to reflect the light of a specific wavelength that has passed through J2. This is the writing optical head 2),
5. A laser oscillator that oscillates a writing laser beam of a specific wavelength. Lens 6, a deflection prism or half mirror 7° focusing lens that transmits the writing laser beam and directs the reflected light from the liquid crystal plate to the light receiving element 9;8. It is comprised of a focus correction section that drives the drive coil 11 of the focusing lens 8 based on the light reception signal of the light receiving element 9 to perform focus correction.

Next, the image writing operation will be explained. The writing laser beam oscillated by the laser oscillator 5 is transmitted through a lens 6,
The beam passes through a deflection prism or half mirror 7, has a beam diameter narrowed down by a focusing lens 8, and enters a liquid crystal panel. The writing laser beam is applied to the transparent base material 28 of the liquid crystal panel. Transparent electrode 2
4. Alignment film 22, liquid crystal layer 21. Alignment film 23. Transparent electrode 2
5 and reaches the light absorption film 2. And the light absorption film 2
An image is written as described above by absorbing a predetermined amount of heat from the writing laser beam and transmitting the heat to the liquid crystal layer 21.

On the other hand, the writing laser beam transmitted through the light absorption film is reflected by the reflection plate 3 in the direction of incidence, and is received by the light receiving element 9 via the focusing lens 8, the deflection prism, or the half mirror 7. The focus correction unit 10 performs focus correction by driving the drive coil 11 of the focus lens 8 based on the light reception signal from the light receiving element 9 so that the focus of the writing laser beam always coincides with the reflection plate 3. An image is written on the liquid crystal plate 1 by scanning the liquid crystal plate with such a writing optical head 4 by a drive unit (not shown).

Next, image display will be explained. As shown in FIG. 1(b), projection light having a wavelength different from that of the writing laser beam from the display light source 12 is projected onto the liquid crystal plate 1 via the lens 13. The projected light transmitted through the liquid crystal plate 1 is magnified by a magnifying lens 14 and projected onto a display screen 15 in an enlarged manner.

In the present invention, as shown in FIG. 5, a liquid crystal panel unit, a writing optical head unit, a display light source 12. Lens 13° Magnifying lens 1
2) By arranging a projection optical system such as No. 4, the drive unit 1
6, during a writing operation, the writing optical head is driven to scan within the writing range of the liquid crystal board to write an image on the liquid crystal board, and when displaying, the writing optical head is shown by a broken line for display. The light source 12 is moved to a position outside the projection optical path. As a result, 2) the projection optical system can be simplified, and the apparatus can also be made smaller.

, Incidentally, in the present invention, the numerical aperture of the focusing lens is NA=0.
47. By using a laser beam with a wavelength of λ-820 nm 2), the beam diameter d can be narrowed down to 1.7 μm.

FIG. 6 is a diagram showing another embodiment of the present invention.

In the figure, the same components as in FIG. 1 are given the same reference numerals. In FIG. 6, the light absorbing film 2 and the reflecting plate 3 are inserted between the transparent base material 28 and the transparent electrode 24.

As a result of this, 2) in addition to image writing in a positive state as explained in FIG. 1, it is possible to write an image in a negative state. In addition, the writing of the negative image in Fig. 6<a) and the writing of the negative image in Fig. 6 (
The writing optical head 4 and the projection optical system in b) enlarged image projection operate in the same manner as described in FIG. 1.

In order to write a negative image on the liquid crystal panel 2), as shown in FIG. 3(b), a voltage 1 is first applied to the transparent electrode 25, which serves as a heating electrode, to raise the cell temperature of the liquid crystal layer 21. After the temperature rises to phase 1, the voltage of the transparent electrode 25 is turned to O and the liquid crystal layer 21 is rapidly cooled to the S phase. Make it negative.

Then, when a writing laser beam is scanned to write an image with a voltage 2 being applied between the transparent electrodes 24 and 25, the cell temperature at the scanned area rises to one phase due to the heat of the writing laser beam. When the cell temperature reaches the N phase after scanning, it is gradually cooled to the S phase by the applied voltage V2 between the transparent electrodes 24 and 25, and a homeotropic structure is formed in the liquid crystal layer 21 scanned by the writing laser beam, resulting in a transparent state. become.

In the embodiment shown in FIG. 6, the light absorbing film 2 and the reflecting plate 3 are inserted between the transparent base material 28 and the transparent electrode 24, so that even if the liquid crystal layer 21 is in a light scattering state, the reflecting plate 3 Since the reflected light can be detected, a negative image can be written.

Furthermore, after writing an image on the liquid crystal plate in a normal positive state, it is possible to partially erase the positive image by scanning the writing laser beam while applying voltage 2 to the transparent electrodes 24 and 25. It is possible.

In the above description, the transparent electrode 25 also serves as a heating electrode, but the transparent electrode 24 may also serve as a heating electrode.

Further, in the above description, the case where enlarged projection is performed on the display screen 15 has been explained, but it can be used for various purposes by combining or changing the projection optical system in various ways. For example, an image may be recorded on a recording member such as a photosensitive material instead of the display screen 15 (2), or a high resolution image written on a liquid crystal plate may be directly projected onto the film without using the magnifying lens 14 for exposure. 2) In addition to writing an image on the liquid crystal plate, for example, binary data may be written on the liquid crystal plate. In this case, binary data for ceiling suspension can be written on the liquid crystal board, and the binary data can be easily rewritten by partial erasure. Note that when the liquid crystal plate is treated as a storage memory for binary data, a decoder is required to decode the binary data from transmitted light or reflected light from the liquid crystal plate.

Furthermore, the present invention can be applied even when the liquid crystal layer 21 in the present invention is a liquid crystal layer containing a mixture of liquid crystal and a dye having light absorption properties, and in that case, the light absorption film 2 is not required.

[Advantageous Effects of the Invention 1] As described above, the present invention makes it possible to reduce the beam diameter of the writing laser beam using a focusing lens, accurately detect the focus using a reflection plate with wavelength selection characteristics inserted into the liquid crystal plate, and to use the focusing lens. Since it can be easily driven and focus corrected, it is possible to write high-resolution images on the liquid crystal panel.

[Brief explanation of drawings]

1 and 5 are diagrams showing one embodiment of the present invention, FIGS. 2 and 4 are diagrams for explaining a conventional liquid crystal display device, and FIG. 3 is a diagram for explaining the transition state of the liquid crystal layer. Figure for, No. 6
The figure is a diagram showing another embodiment of the present invention. 1...Liquid crystal plate 2...Light absorption film 3...Reflection plate±...Writing optical head 5...Laser oscillator 8...Focus lens 9...Light receiving element 10...Focus correction Part 12...Display light source

Claims (4)

[Claims] (1) It has at least a liquid crystal layer, a pair of alignment films sandwiching the liquid crystal layer, a transparent electrode, and a transparent base material, and a predetermined amount of light of a predetermined wavelength is transmitted between one of the transparent electrodes and the transparent base material. absorb,
A liquid crystal plate configured by inserting a light absorption film that conducts absorbed heat to a liquid crystal layer, a reflection plate that reflects light of a predetermined wavelength that has passed through the light absorption film in the direction of incidence, and a laser that emits light of a predetermined wavelength. an oscillator, a focusing lens that narrows down the beam diameter of the light of the predetermined wavelength, a light receiving element that detects the reflected light from the liquid crystal plate, and a focal point that drives the focusing lens with a light reception signal of the light receiving element to perform focus correction. a writing optical head that scans the liquid crystal plate to write an image; and a writing optical head that projects the projection light from the display light source onto the liquid crystal plate from the incident direction of the light of the predetermined wavelength, and A liquid crystal display device comprising: a projection optical system that projects an image recorded on a liquid crystal plate by transmitted light transmitted through the liquid crystal panel. (2) The liquid crystal plate is composed of a liquid crystal layer mixed with a dye that absorbs at least a predetermined amount of light of a predetermined wavelength, a pair of alignment films sandwiching the liquid crystal layer, a transparent electrode, and a transparent base material, one of which is transparent. 2. The liquid crystal display device according to claim 1, further comprising a reflective plate that reflects light of a predetermined wavelength inserted between the electrode and the transparent base material. (3) The liquid crystal display device according to claim 1, wherein binary data is written on the liquid crystal plate by the writing optical head. (4) Projection light is projected onto the liquid crystal board on which the binary data has been written, and based on the transmitted light or reflected light from the liquid crystal board, the
4. The liquid crystal display device according to claim 3, further comprising a decoder for decoding value data.