JPS619692A - Image display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image display device, and particularly to an image display device capable of high-speed operation and high contrast.

2. Description of the Related Art Conventional Structures and Points of Interest With the recent development of the information society, the demand for image display devices has increased, and various attempts have been made to increase the screen size, improve performance, and make them flat. Among these, light valves using liquid crystals have been actively researched and developed because they enable large screen display, high brightness, and high resolution. Conventional writing methods for liquid crystal light valves include thermal writing, optical writing, and writing using electrical signals. Thermal writing method is 1. For example, a smectic liquid crystal is scanned with a YAG laser, and the liquid crystal layer is heated and rapidly cooled to change from a transparent state to a light-scattering state. The image is then displayed by transmitting light from a projection xenon lamp. This is a method of doing this. The thermal writing method has a drawback in that high-speed writing is not possible due to poor thermal response characteristics. As an optical writing method, there is a reflective light valve in which a photoconductive layer and a liquid crystal are integrated. This method is
An image is obtained by applying incident light to a photoconductive layer such as CdS, converting voltage changes depending on the intensity of the light into voltage distribution of a liquid crystal layer, and changing the polarization angle of the projected light. In this method, although a light blocking layer is provided between the photoconductive layer and the liquid crystal layer, sufficient contrast cannot be obtained because the photoconductive layer is affected by the projection light. Furthermore, since liquid crystal is used, writing and erasing speeds are still insufficient. On the other hand, a method has been attempted in which a matrix electrode is provided in a ferroelectric material having an electro-optical effect and image display is performed by electrical switching (Japanese Patent Application Laid-open No. 1983-65177), but this method reduces the structure. When displaying complex, large-screen, high-density images, there are problems such as lower production yields, large capacitance between electrodes, and the need for high voltage to polarize the ferroelectric material. There are some driving difficulties.

OBJECTS OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide an image display device that is high-speed, has good contrast, and has a simple structure.

Structure of the Invention Therefore, the present invention provides a transparent ferroelectric layer having an electro-optic effect, a photoelectric conversion film formed on the ferroelectric layer, and a first photoelectric conversion film formed on the photoelectric conversion film. a second electrode formed on the ferroelectric layer at a position separated from the first electrode, a circuit for applying a voltage between the first and second electrodes, and the photoelectric conversion means for scanning a film with a first light having intensity changes according to image information; and a means for making a second light for modulation enter onto a surface of the dielectric layer opposite to the photoelectric conversion film. and optical means for obtaining image output light by transmitting through the ferroelectric layer and then emitting or reflecting from the film, thereby providing an image display device that is fast, has high contrast, and has a simple structure. It consists of

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an overall configuration diagram of an image display device according to a first embodiment of the present invention. (10) is a light source, (11) is a polarizer, (b) is a transparent ferroelectric material having an electro-optic effect, and 03) is an analyzer. 04), (b)) are the first electrode and second electrode, respectively, (e) is the voltage applied e1)
is a rotating polygon mirror, and the display element r is illuminated by a laser beam (20).
t12.1').

FIG. 2 shows a detailed plan view of the display element (b) of FIG. 1, and FIG. 3 shows a sectional view of one basic component in the second side view. In these diagrams, those that have the same function,
Parts with the same function are given the same number. The operation of the present invention will be explained using FIGS. 1 to 3.

First, the light emitted from the light source α0) is linearly polarized by the polarizer 01) and passes through the transparent ferroelectric layer (b). In the electrode configuration shown in Figures 2 and 3, the layer (B) is subjected to electric field changes according to the laser intensity, so a light delay phenomenon (also called retardation) occurs due to changes in the refractive index. The light becomes elliptically polarized, and only the component that coincides with the polarization axis of the analyzer (13) is transmitted, so that the transmitted light has varying strengths and forms an image pattern. The light emitted from light source 00) is
The transmittance T when passing through the analyzer 03) is given by the following formula.

Here, A is the transmittance determined by the reflection loss and structure of the polarizer (11), analyzer (13), and transparent ferroelectric layer (I2), B is a constant, G is a constant, and E is the electric field. , t is the effective thickness of the element to which the electric field is applied, and λ is the wavelength. As is clear from equation (1), the amount of passing light can be changed as the applied voltage changes.

In FIG. 3, the first electrode (15) and the second electrode (14)
) is inserted between the two, and by closing this, the voltage of the power supply (e) is applied. Since the photoelectric conversion film has a high resistance in the dark state, the applied voltage is distributed by the capacitance of the photoelectric conversion film (16) and the capacitance between the first electrode (15) and the second electrode 04). While applying voltage,
When the laser beam (generated from the laser light source (19)) is reflected by the rotating polygon mirror (QI) and scans the display element (as shown in Figure 2), the resistance of the photoelectric conversion film (16) decreases and the laser beam enters. Translucent ferroelectric layer (
12) and the photoelectric conversion film (16). Therefore, when the switch Q1) is opened when the incident light has finished scanning, the area illuminated by the incident light will be the first
The voltage between the electrode (15) and the second electrode (14) will increase and the second light (10) will pass through. Furthermore, a resistor α7) may be connected as shown in FIG. 4 in order to give a constant time constant to the change in voltage distribution caused by the scanning light.

Note that in order to impart gradation to the transmitted light, the intensity of the scanning laser beam may be changed and the voltage distribution may be made different for each pixel.

Next, the manufacturing method of the present invention will be explained.

The transparent ferroelectric layer (b) may be sintered or single crystal, for example, LiNbO5, Bias 1Ozo, Bi1
2 Ge 012 .

KH2PO4, NH4H2PO4, GaAs, Li
NbO3.

LiTaO3 and P L Z T are used. Alternatively, the above material may be formed as a thin film on a transparent substrate by sputtering or the like. On top of that, Mo,, Ta,
W.

A second electrode is obtained by forming a metal electrode (1→) of Ti, Cr, AJ, etc. in a pattern as shown in FIG. 2. In FIGS.
Layer (b) to form the first electrode (15) that intersects with →
At the upper position, a photoelectric conversion film (16) consisting of the ■-■ group, n-v group 1■ group, or
It is formed with a thickness of 00 μm. The dark specific resistance of the photoelectric conversion film 06) needs to be sufficiently high, and the film 06) that satisfies this need
The materials include Zn5e-Zn I-X CdxTe heterojunction, a-8i:I(, 5eAs2Se3,
Inorganic materials such as AS2S3, phthalocyanine.

Organic materials such as PVK and pyrazoline are particularly suitable for satisfying the above conditions. On the photoelectric conversion film (16) thus formed, a first electrode (15) that transmits the laser beam (20) is made of Au, Pt, In.
2O3.

By forming SnO2 or the like by vapor deposition or the like, an image device according to the present invention is completed.

In addition, in order to prevent the photoelectric conversion film (16) from being adversely affected by the light (10) coming from the back side, as shown in FIG. 5(a).

) or (c) is formed on the light shielding layer as shown in (1)).

The former H blocks light at the corresponding portion of the ferroelectric layer (12), and the latter (goods) blocks light just before the film (16).

FIG. 6 shows a second embodiment of the present invention, in which the electro-optic effect of the ferroelectric material (I2) exhibits a longitudinal property. For example, this is a case such as the Pockels effect, and the operation in this case can be considered in exactly the same way as the cases shown in FIGS. 1 to 5.

However, the unique configuration in FIG. 6 is that the projected light is a reflective type, that is, the incident light (10) returns as reflected light (+ob), and the second electrode (+4a) is made of a transparent ferroelectric material. By disposing the layer (12) on the opposite side of the electrode (15), the basic effect of the present invention can be obtained in exactly the same manner.

FIG. 7 shows another embodiment, and compared to the case of FIG.
photoelectric conversion film (c) and an electrode (c) on the photoelectric conversion film
The difference is that it has been set up. In this case, the dielectric strength voltage of the photoelectric conversion film can be reduced to about V as in the case of FIG. 3, and the range of selection of the photoelectric conversion film is widened.

The first scanning light (to the first scanning light) and the second scanning light (zob) may be synchronized or may be operated separately, for example, by the first scanning light) and the second scanning light (zob).
An operation such as the (11+1)th field screen is also possible. FIG. 8 shows a case where an electric field oblique to the entrance path of the light α0) is obtained, resulting in a transmission type optical shutter. In FIG. 8(a), a photoelectric conversion film (16) and an electrode (at a shifted position) are formed with a ferroelectric layer (b) in between.

FIG. 8(b) shows a case where a second photoelectric conversion film (b) is provided between the electrode e in FIG. 8(a) and the ferroelectric layer (12).

In FIGS. 1 to 8, between the first photoelectric conversion film 06) and the ferroelectric layer (b), and the second photoelectric conversion film (c),
The operation is the same even if an electrode is provided between (c) and the ferroelectric layer (b).

In the embodiments of the present invention, the light incident on the charge conversion film (16) is a laser beam, but the present invention is not limited to this, and for example, a two-dimensional light such as a light emitting diode or a cathode ray tube is used. It goes without saying that the incident light image may also be an image of the incident light.

Further, the principles of the present invention can also be applied when the light source 00) in FIG. 1 is a laser beam.

Effects of the Invention As described above, the present invention is an image display device that combines a transparent ferroelectric material and a photoelectric conversion film, but the storage operation is improved by separating the first electrodes corresponding to pixels. possible,
It is possible to realize an excellent image display device that has high contrast and can obtain high operating speed because high voltage can be applied to the ferroelectric material using the photoelectric switching effect of the photoelectric conversion film.

[Brief explanation of drawings]

1 is a perspective view showing the overall configuration of an image display device according to a first embodiment of the present invention, FIG. 2 is a plan view of the first embodiment of the present invention, and FIG. 3 is a sectional view thereof. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are sectional views showing other embodiments of the present invention, respectively. 00)・・・・・・・・・・・・・・・Light source (11)・・
・・・・・・－・・・・・・Polarizer (b)）・・・・・・
......Transparent ferroelectric layer 03) having electro-optic effect Analyzer θ4)
・・・・・・・・・・・・Second electrode (15)...
・・・－・・・・・・・First electrode 06)・・・・・・・
......Photoelectric conversion film (e)...
・・・・・・Voltage application means (1g)・・・・・・・・・
...Incident light source patent applicant for laser etc. Matsushita Electric Industrial Co., Ltd. Agent Kenbu Niimi (1 other person) 1 Figure 1ρ Figure 2 Figure 3 Figure 5 (L) Figure 4 Figure 6 Figure 8 ('2-) Figure 7 (G9

Claims (3)

[Claims] (1) A light-transmitting ferroelectric layer having an electro-optical effect, a photoelectric conversion film formed on the ferroelectric layer, a first electrode formed on the photoelectric conversion film, and the ferroelectric a second electrode formed on the body layer at a position separated from the first electrode; a circuit for applying a voltage between the first and second electrodes; a means for scanning with a first light having intensity changes; and a second light for modulation is incident on the surface of the ferroelectric layer opposite to the photoelectric conversion film; 1. An image display device comprising: an optical means for obtaining image output light by emitting or reflecting light from the film after passing through the film. (2) A second electrode is provided between the second electrode and the ferroelectric layer.
Claim No. (1) in which a photoelectric conversion film of
The image display device described in Section 1. (3) The image display device according to claim (1) or (2), wherein a plurality of electrodes formed separately corresponding to each pixel are used as the first electrode.