JPS6022339Y2 - display device - Google Patents

Description

[Detailed description of the invention] The present invention is based on changes in the optical properties of scattering properties at the phase transition point of transparent ferroelectric materials such as circle 2T and PBZT, electric field control properties of the optical properties, and changes in the optical properties of the above optical properties. This invention relates to a bulb-type display device that utilizes non-volatile memory properties.

Note that circle 2T is an abbreviation for a material in which a mixed crystal of lead zirconate and lead titanate is doped with lanthanum, and PB'ZT is an abbreviation for a material in which a mixed crystal of lead zirconate and lead titanate is doped with bismuth. .

In the display device of the present invention, an electric field is applied to an electrode coated on a transparent ferroelectric material to set the entire surface of the ferroelectric material as a light valve in an optically uniform state.

Then, due to this non-volatile memory property, the set state is maintained even after the electric field is removed, so by irradiating the transparent ferroelectric with heat rays, the temperature of the transparent ferroelectric can be partially controlled, and the ferroelectric can be partially An optical system that can convert the light valve surface into a paraelectric material, write information by creating optical non-uniformity on the light valve surface, and display this written non-uniformity as an optical image.
For example, a schlieren lens system) is used to display the image as an optical image.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a light beam diverging from a projection point light source 1 is converted by a collimator lens 2 into a parallel light beam that is perpendicularly incident on the surface of a light valve 6. As shown in FIG.

A beam emitted from a writing heat ray source (for example, a carbon dioxide laser) 4 is given optical image position information and contrast information by a deflector and a modulator 5, and is reflected by a gicroic mirror 3 to produce a light beam. Incident perpendicular to the valve surface.

The light valve 6 is made of, for example, PLZ with a particle size larger than 2μ.
It consists of T' ceramic 61 and transparent conductive electrodes coated on both sides.

As shown in Figure 2, the transmission characteristics of this PLZT ceramic 61 (scattering directivity in this thermally depolarized state is indicated by the symbol C) are as follows: in the paraelectric state, the electrically depolarized state in the ferroelectric state (this The scattering directional characteristics in the state shown by symbol A) and the electrically polarized state (indicated by symbol B) are very sharp.

Therefore, the pulse width and pulse duration applied to the transparent conductive electrode 62 of the light valve 6 are selected to appropriate values by the pulse generator 7, and the electrically depolarized state shown in FIG.
If the LZT is fixed, the scattered light is irradiated onto the screen 10 by the lens 8 without being converged on the stopper 9, so that the screen surface becomes brighter.

Note that the stopper 9 only needs to be non-transparent.

Even if the applied signal from the pulse generator 7 is removed, this state is maintained for a long time due to the non-volatile memory property of PLZT.

Next, a part of the PLZT is heated to a temperature of about 55°C using a hot wire for writing.
If it changes to a paraelectric state by heating it above, the scattering characteristics of the heated part become sharp, as is clear from FIG. 2, and therefore the light after passing through the light valve 6 Mainly the PLZ is converged by the lens 8 and placed on a small stopper 9 located at its focal point.
The light transmitted through the paraelectric sheath portion of the T ceramics 61 is collected.

That is, the stopper 9 protects the screen 10 from light passing through the paraelectric sheath portion of the PLZT ceramics 61.

Therefore, the light projected onto the screen 10 is reduced in accordance with the writing pattern, so that a visible pattern is formed on the screen 10.

Therefore, with the device of the present invention, it is possible to write black characters on a white screen surface.

Further, by controlling the writing heat ray dose using the modulator 5, the transition domain amount of PLzT can be controlled and the black level can be controlled, so that halftone display is also possible.

Furthermore, by providing an aperture instead of the stopper 9, it is of course possible to write white characters on a black background.

In addition, the erasure is performed by the pulse generator 7 using a depolarization signal,
For example, this is possible by reapplying a pulse signal of several tens of KHz.

Conventionally, writing technology using hot wire is known as a writing technology that utilizes the solid phase, liquid phase, and intermediate phase of liquid crystal.

However, the present invention utilizes the thermo-optical properties of transparent dielectrics, especially the phenomenon of transformation from the ferroelectric state of the crystal to the paraelectric state, for writing with hot wires, and also utilizes the transmission properties of the same crystal. Compared to light valves with a structure with a conductive film in between, the structure is simpler as no analyzer or polarizer is required, and the response speed is not limited by the time constant of the photoconductive film and ferroelectric material, making it faster. It is very superior in that it eliminates the need for an element and can improve brightness.

Also, compared to the crystal type, it has a wider operating range at low temperatures and a faster response speed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of scattering directional characteristics of a transparent ferroelectric material of the same embodiment. 1... Point light source for projection, 2... Collimator lens, 3... Guicroic mirror, 4...
...Writing hot ray source, 5...Deflector and modulator, 6...Light valve, 7...Pulse generator, 8...Projector lens , 9
...Stopper, 10...Screen.

Claims (1)

[Scope of utility model registration request] a light-transmitting ferroelectric material having conductive electrodes on both sides; a pulse generator for applying a voltage between the conductive electrodes; a writing hot ray source for selectively converting the ferroelectric material into a paraelectric material; A light source section for making parallel light beams incident on the ferroelectric material, a focusing means for collecting the light transmitted through the ferroelectric material, and selectively blocking only the light passing near the focal point of the focusing means. 1. A display device comprising a light passing means for selectively passing through a streaking means or only the light passing means.