JPS61236533A - Optical element - Google Patents

Abstract

PURPOSE:To realize the formation of a sharp image having high contrast and high resolution by the constitution consisting in sandwiching a polymer liquid layer which is deposited by heating and is dissolved by cooling between a substrate and protective plate. CONSTITUTION:A ray 6-1 which is made incident to a low temp. region 4 of the polymer liquid layer 2 sandwiched between the substrate 1 and the transparent protective plate 3 passes straightly the layer 2 and is emitted from the substrate 1. An incident ray 6-2 to a region 4a where the polymer deposits by the heating of an IR beam 5 irradiated thereto according to an information signal is scattered. The excellent scattering characteristic is thus obtd. and the sharp image having high contrast and high resolution is obtd. Since there is no limitation in the visual angle, the element does not give the feel of eye's fatigue even after long-period use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel optical element, and particularly to an optical element that utilizes the light scattering properties of a soluble polymer.

In recent years, with the development of office automation (OA), display devices have been widely used in the field of executive office equipment. It is desirable for such a display device to be one that does not cause eye fatigue even when used for a long time. Conventionally, non-emissive display devices such as electroluminescent display devices (EGD) and liquid crystal display devices (LCD) are known as such display devices. However, ECDs have the drawbacks of low display contrast, and LCDs have even narrower viewing angles. Further, similar drawbacks occur when these are used as light modulating elements such as optical shutters.

The present invention was made in view of the above drawbacks of conventional elements, and provides a high-quality display element with a wide viewing angle, excellent clarity, and does not cause eye fatigue even when used for a long time. , high contrast as a light modulation element,
The object of this invention is to provide an element that is less dependent on the angle of prior incidence.

[Means for Solving the Problems] Hereinafter, the basic configuration of the present invention will be explained using FIG. 1 corresponding to an embodiment. In the figure, 1 is a substrate, 2 is a polymer liquid layer, and 3 is a transparent protective plate.

When the optical element is a transmission type, the substrate 1 is made of glass,
Materials that transmit light such as plastics are used, and in the case of reflective types, materials that do not transmit light such as semiconductors such as silicon, ceramics, metals such as aluminum, opaque plastics, etc. Alternatively, a material in which a metal film is deposited on the surface of the above-mentioned transparent material may be used. The polymer liquid layer 2 is a liquid layer made of a solvent containing a soluble polymer. Examples of the soluble polymer constituting this polymer liquid layer include wood-loving polymers such as N-isopropylacrylamide, methyl vinyl ether, ethylene oxide, and propylene oxide. Polymers obtained from the above, copolymers between them, copolymers containing these as main components, etc. are suitable.

On the other hand, the solvents constituting this polymer liquid layer include water,
or methanol, ethanol, ethylene glycol,
With organic solvents such as alcohols such as glycerin, ketones such as acetone and methyl ethyl ketone, amides such as dimethylformamide, hexamethylphosphorylamide and dimethylacetamide, amines such as pyridine and triethylamine, and sulfur-containing solvents such as dimethyl sulfoxide. A mixed solvent with water, or potassium chloride in those solvents,
Solutions to which solutes such as sodium chloride and urea are added are suitable. Moreover, the thickness of this polymer liquid layer 2 is I
gm to 1000 g m is appropriate, preferably Ig
m to 100 g ts is the optimal range. As the transparent protection plate 3, a transparent body such as glass, plastic, dielectric, etc. is used. Note that in order to improve the contrast, a visible light reflecting layer and a visible light absorbing layer (not shown) may be provided on the surface of the substrate 1.

[Operation] Next, the principle of operation (imaging, light modulation) of this optical element will be explained using FIG. 1 as well. Note that FIG. 1 shows an example of a transmission type.

First, when the polymer liquid layer 2 is not heated (that is, in a low temperature state), the soluble polymer exists dissolved in the solvent, so the light ray 8-1 incident on the low temperature region 4 of the polymer liquid layer 2 is It passes directly through the polymer layer 2 and is ejected from the substrate 1. On the other hand, when a predetermined position of the polymer liquid layer 2 is heated by external heating means such as irradiation with an infrared beam 5 according to the information signal,
The soluble polymer within the heating region 4a precipitates and exhibits light scattering properties. Therefore, the light beam 8-2 that enters the heating region 4a is scattered (diffused). This heating area 4a
When the temperature drops, it returns to its original translucent state.

As is clear from the above explanation, scattering of soluble polymers (
Light modulation and display can be performed by thermally controlling the state of non-transparent) and non-scattering (transparent).

[Example] Embodiment 1 Hereinafter, an embodiment of the present invention will be explained with reference to FIG. The thickness of the substrate 1 and transparent protection plate 3 is 0.3 mm.

A cell container was formed by using sufficiently clean glass plates having a size of 50 x long, and adhering the two glass plates facing each other at a distance of 10 mm using a Mylar film as a spacer. Next, add 5 g of isopropylacrylamide and 30 mg of ammonium persulfate to 100 ml of cold water.
80 ml of tetramethylethylenediamine was added and degassed using an aspirator.

Thereafter, the mixture was allowed to stand at room temperature for 30 minutes to perform polymerization, resulting in a polymer solution. This polymer solution was filled and sealed in the cell container to form a polymer liquid layer 2, thereby producing an optical element.

When the thus obtained optical element was scanned and irradiated with a semiconductor laser beam with an output of 20 mW and a wavelength of 830 nm, focusing on the polymer liquid layer 2 from the back surface of the element according to the information signal, a predetermined area of the polymer liquid layer 2 was irradiated. It was confirmed that there was a change from translucency to opacity. This is considered to be because the semiconductor laser beam is absorbed and converted into heat in the irradiated region of the polymer liquid layer 2. Note that the heating time by the semiconductor laser beam was instantaneous, and the polymer liquid layer 2 immediately showed its original translucency.

As a result of repeated irradiation experiments with the above laser beam, it was found that both reproducibility and signal response were practically sufficient.

Example 2 4 g of N-isopropylacrylamide, 0-5 g of hydroxyethyl methacrylate, 30 g of ammonium persulfate
mg was dissolved in 100 mg of cold water, 60 P of tetramethylethylenediamine was added, and the mixture was degassed using an aspirator. Thereafter, the mixture was allowed to stand at room temperature for 30 minutes to perform polymerization, resulting in a polymer solution. An optical element was produced in exactly the same manner as in Example 1 except for using this soluble polymer solution.

When the optical element thus obtained was subjected to imaging and light modulation experiments similar to those in Example 1, good results similar to those in Example 1 were obtained.

Example 3 5 g of polyethylene oxide (average molecular weight 400, manufactured by Kishida Chemical Co., Ltd.) was mixed with 50 mji' of water to prepare a polymer solution. An optical element was produced in exactly the same manner as in Example 1 except for using this soluble polymer solution.

When the optical element thus obtained was subjected to imaging and light modulation experiments similar to those in Example 1, similarly good results were obtained.

In each of the above embodiments, transmissive optical elements have been described, but even when reflective optical elements are used,
Similar characteristics can be obtained.

[Effects of the Invention] As explained above, since the optical element according to the present invention has excellent scattering properties, it is possible to obtain clear and high-resolution images with high contrast, and it is also possible to eliminate limitations on the viewing angle. . Therefore, even when used as a display device for a long time, the eyes will not feel tired. Furthermore, since the polymer liquid layer is modulated by slight heating, the power consumption of the display device can be reduced. Furthermore, high frequency modulation is also possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the basic concept of the present invention. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Polymer liquid layer, 3...Transparent protection plate.

Claims (1)

[Claims] (1) An optical element in which a polymer liquid layer consisting of a soluble polymer that is precipitated by heating and dissolved by cooling in a solvent is sandwiched between a substrate and a protective plate.