WO1992009003A1

WO1992009003A1 - Liquid crystal shuttering device

Info

Publication number: WO1992009003A1
Application number: PCT/JP1991/001545
Authority: WO
Inventors: Shigeru Sugimori; Hiroyoshi Onnagawa
Original assignee: Chisso Corporation
Priority date: 1990-11-14
Filing date: 1991-11-12
Publication date: 1992-05-29

Abstract

A liquid crystal shuttering device which can be driven with a comparatively low power consumption and is required to use no polarizing element. A liquid crystal cell is so configured that between two or more glass-like substrates (1) made of a substantially transparent material and not oriented or so processed as to be in the state of random irregularity, via spacers (2), a randomly oriented liquid crystal (5) is sealed in the cell, and that electrodes are bonded to the subtrates (1). This device can be utilized light-transmitting or light-reflecting liquid crystal shuttering devices such as a light shield of a welding mask, a shutter for an optical printer and an electronic optical diaphragm.

Description

P T / JP91 / 01545 Clarification

LCD shutter device

Technical field

The present invention relates to a liquid crystal shutter device. More specifically, it relates to a device for switching between transmission and blocking of light by applying a voltage to the liquid crystal phase. , Background technology

There are various types of liquid crystal shutter devices that utilize the optical anisotropy and induced anisotropy, which are the characteristics of liquid crystal substances. Currently, the most practically used method is the twisted nematic type (TN type), and there is the super twisted nematic type (STN type) that is an improved version of the method. In addition, as a high-quality display method, there is a method using a thin film field effect transistor (TFT) using an active element and a metal-insulator-metal diode (MIMM). In addition to these, the method using ferroelectric liquid crystal.

In the liquid crystal shutter device by these methods, it is necessary to orient the liquid crystal molecules in a certain direction at the interface between the liquid crystal interface and the electrode plate, and to orient the liquid crystal molecule orientation angle to 90 ° or more. .. In addition, color conversion of liquid crystal display elements has been promoted recently, but in the color display method, it is necessary to use a color filter in addition to the polarizing element, so the utilization efficiency of the light amount of the light source becomes extremely poor. There are drawbacks. Therefore, a liquid crystal shutter device that does not require a polarizing element is desired. As one solution to this problem, a polymer liquid crystal dispersed display element that does not use a polarizing element has been proposed. However, there are problems in selection of polymer materials, dispersion method of dispersed liquid crystal, particle size, etc., and in addition, driving voltage of several 10 V to several 100 V requires high driving voltage.

In addition, as a method that does not use a polarizing plate, a dynamic scattering method (DS method), a white film such as a cholesteric-nematic phase transition type display element is used. Single-lens type methods are known, but these methods have high power consumption, are not practical, and are rarely used. Recently, Yoshino et al. Have proposed a liquid crystal cell based on the transient scattering display method (TSM) (Jpn. J. Appl. Phys., 23 (1984) L 385). This type of liquid crystal cell uses ferroelectric liquid crystal and flat transparent glass that has been oriented as an electrode plate, but its drive voltage is as high as several 10 to several 100 V. ,

An object of the present invention is to solve these problems and to provide a liquid crystal shank device which does not require the use of a polarizing element and which can be driven at a power consumption or a driving voltage equal to or less than that of the conventional method. .. Disclosure of the invention

As a result of our research, the inventors of the present invention have found that a polarizing element can be made non-uniform by enclosing nematic liquid crystal in a disordered alignment state with a space between two or more glass-like substrates without alignment treatment. We succeeded in obtaining the necessary liquid crystal shutter device.

In addition, two or more glass-like substrates with one or more inner surfaces roughened are stacked, and a nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, ferroelectric liquid crystal is interposed between them by a spacer. It has been found that the object of the present invention can also be achieved by encapsulating a kind of liquid crystal and antiferroelectric liquid crystal in a disordered alignment state.

The first aspect of the present invention is to superimpose two or more transparent substrates, each of which is essentially made of a transparent material, and which has not been subjected to an alignment treatment, and enclose a nematic liquid crystal between them through a spacer. However, the liquid crystal shutter device is composed of cells in which transparent electrodes are attached to the uppermost part of the transparent substrate and the transparent electrode or the opaque electrode is attached to the lowermost part thereof.

The second aspect of the present invention is to superimpose two or more transparent substrates, each of which is essentially made of a transparent material, and whose one or more inner surfaces have been roughened, and to place a spacer between them. Through the nematic liquid crystal, , A kind of steric liquid crystal, smectic liquid crystal, ferroelectric liquid crystal and antiferroelectric liquid crystal are encapsulated in a disordered alignment state, and a transparent electrode is placed at the top of the transparent substrate and the bottom is placed at the bottom. It is a liquid crystal shutter device consisting of cells with transparent or opaque electrodes attached. In the above first and second inventions, an active element may be used instead of the transparent electrode. In the roughening treatment, the transparent substrate may be directly treated, or after the resin coating is formed on the transparent substrate, the roughening treatment may be performed on the resin coating. As the surface roughening treatment, for example, it is also considered that an uneven surface is formed by engraving a large number of grooves having a depth of 0.5 to 100 and a width of 0.5 to 100. Brief description of the drawings

FIG. 1 is a sectional view of a liquid crystal shutter device of the present invention composed of two electrode substrates, FIG. 2 is a sectional view of a liquid crystal shutter device of the present invention composed of three electrode substrates, and FIG. A transparent resin film is provided on the electrode substrate, and the surface is roughened. A cross-sectional view of one device of the liquid crystal shirt of the present invention composed of two sheets. Fig. 4 shows a transparent resin film provided on the electrode substrate and its surface. FIG. 3 is a cross-sectional view of a liquid crystal shutter device of the present invention composed of three roughened surfaces.

The transparent substrate used in the present invention is a flat plate or a film made of an essentially transparent material, and specific examples thereof include a glass plate, an acrylic resin plate, and a polyester film. It is necessary that this transparent substrate is not subjected to the alignment treatment such as the glass substrate rubbing treatment S i 0 or the oblique vapor deposition treatment such as T i O z used in the conventional liquid crystal cell. Furthermore, this transparent substrate is preferably rubbed with a powder such as carborundum on the inside surface when made into a cell, with a solvent treatment force, or with a depth of 0.5 to 100 and a line width. It is semi-transparent or opaque by randomly or irregularly etching or mechanically processing 0.5 to 100 u to form random uneven surfaces (grooves). It is preferable to have a clear state.

The nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, ferroelectric liquid crystal or antiferroelectric liquid crystal is used as the liquid crystal to be sealed between the substrates. Good. Regarding the refractive index of liquid crystal, the value in the major axis direction is used when the one with positive dielectric anisotropy is used, and the value in the minor axis direction is used when the one with negative dielectric anisotropy is used. It is desirable to select a liquid crystal that has a value close to or close to the refractive index.

In the device of the present invention, it is necessary that the encapsulated liquid crystal is not oriented in one direction in the cell but is disordered. As a method for this, as described above, the inner surface of the transparent substrate in contact with the liquid crystal is not subjected to any alignment treatment, or, as described above, at least one of the surfaces is roughened.

(The above-mentioned groove-like treatment is also applied) to form a random uneven surface. Rough surface treatment is performed by randomly rubbing with powder such as carborundum of about 1 to 100, surface treatment with chemicals such as solvent to make the surface frosted glass, or by cutting or etching. There is a method of forming a regular or irregular groove having a width of 0.5 to 1 and a line width of 0.5 to 100. When forming a groove, if the size of the groove is outside the above range, a sufficiently rough surface cannot be obtained. Although these treatments may be performed directly on the transparent substrate surface, a transparent resin film having a thickness of 0.1 to 100 is formed on the transparent substrate surface, and the surface of this transparent resin film is roughened. Good. When the transparent resin film is formed, its thickness is preferably 5 to 15 m. The rough surface treatment increases the light scattering effect and improves the contrast when the shutter is opened and closed.

The transparent electrode or the opaque electrode is preferably provided on the transparent substrate after the roughening treatment, but may be provided before the above treatment and the transparent electrode surface may be simultaneously roughened. The transparent electrode does not necessarily have to be provided on the inner surface of the cell (the surface in contact with the liquid crystal), but may be provided on the outer surface.

The spacer is a liquid of a certain thickness so that the transparent substrates do not come into contact with each other. “It is interposed in order to maintain the crystal phase, and the interval is not particularly limited, but 5 to: I 0 0 m is desirable.

As the transparent electrode, tin oxide film, oxide oxide film, tin oxide (ITO) oxide film, active elements combined with transistors, etc. can be provided. The opaque electrode may be an aluminum film, a chrome film, or the like. These electrodes are attached and formed on at least a part of the transparent substrate by a usual method such as a spray method, a vacuum deposition method, or a high frequency sputtering method, which is a method for forming a transparent electrode of a liquid crystal cell. If more than two substrates are used, the electrodes attached to the intermediate substrate must be transparent, but one of the outer or top or bottom substrate is a transparent electrode, while the other is transparent. It may be an opaque electrode. When an opaque electrode is used, it can be used, for example, as a device for a liquid crystal shutter by reflected light. BEST MODE FOR CARRYING OUT THE INVENTION

1 and 2 are cross-sectional views of a liquid crystal shutter device in which an electrode is provided inside, showing an embodiment of the present invention. FIG. 1 shows a case of two transparent substrates, and FIG. 2 shows a case of three transparent substrates. .. This device comprises a transparent substrate 1, a liquid crystal 5 in a disordered alignment state enclosed between these substrates 1 through a spacer 2, and transparent electrodes 3 and 4 formed on these substrates. And a power supply 6. The facing surface of the transparent substrate 1 which is in contact with the liquid crystal 5 is not subjected to the alignment treatment, and is left as a flat surface or is roughened, for example, it is randomly rubbed with a random force to form a random uneven surface. There is.

When a voltage was applied to the electrodes 3 and 4 from the power supply 6 of the liquid crystal shutter device manufactured in this way, the contrast ratio of the liquid crystal element was found to be 1: 1.5 for two substrates, about 1.5, In the case of three substrates, it was improved to 1: 2.0 or more, and the driving voltage was 10 to 20 V. On the other hand, the roughened surface tends to have higher transparency than the untreated surface. However, the contrast ratio was not so different.

In Figures 3 and 4, the substrates are 2 and 3, respectively, and the electrodes 3 and 4 and the transparent resin film 7 are provided on the surface facing the liquid crystal 5, and the surface of this transparent resin film 7 is carborundum as above. A cell is formed by randomly rubbing to form a rough surface (random uneven surface), and enclosing the liquid crystal 5 in a disordered alignment state so as to be in contact with the rough surface. Although the electrodes 3 and 4 are directly attached to the transparent substrate 1, they may be attached on the transparent resin film after it is formed.

A transparent resin film was provided on a transparent substrate, and a voltage was applied in the same way to the liquid crystal shutter device of Fig. 4 manufactured by roughening this, and the contrast ratio of the liquid crystal element was 1: 1.5 to 2 It was 0. When a piece of paper on which letters were written was placed under the liquid crystal cell of this device and the voltage application was repeated between both electrodes, the letters below could be seen or disappeared. The operating voltage when nematic liquid crystal was used as the liquid crystal was 15 to 25 V.

If a ferroelectric smectic C liquid crystal is filled in a similar cell with a cell thickness of 15 instead of a nematic liquid crystal and a liquid crystal shutter is configured, even if a pulse of 5 msec at ± 20 V is applied, the liquid crystal shirt It was practical as one.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples. Example 1

Random ruggedness (so-called frosted glass) was rubbed by randomly rubbing one side of a commercially available 0.5 mm thick transparent flat glass (60, Χ 60) with a force of 50 mesh. Treated to form. An ITO film was attached to the treated surface by a scatterer to form a transparent electrode.

Divide this flat glass into two pieces so that the ITO film attachment surfaces face each other. _A cell is made by pasting together with a spacer of .10 m and a nematic liquid crystal composition (GR-63 manufactured by Chitsso Co., Ltd.) is enclosed between two glass to fabricate a liquid crystal shutter device. did.

This device did not appear opaque when looking at the letters of Shin Feng through the glass surface, but it became transparent by applying an AC voltage of 100 Hz and 10 V between both transparent electrodes, and the letters were read. It was found that the switching effect of light can be obtained by applying a voltage. The contrast ratio at this time was 1: 1.5.

Comparative example 1

An apparatus was prepared in the same manner as in Example 1, except that the same orientation as in Example 1 was applied to the flat glass by a Rabbing method in which one surface was rubbed with a cloth in one direction. When I saw the letters of Shincho through the glass surface of this device, the letters were transparent and readable. Even when applied between both transparent electrodes in the same manner as in Example 1, there was no change and it was transparent, and the effect of optical switching was not obtained.

Example 2

Among the roughened flat glass obtained in Example 1, the glass with the ITO film adhered to one surface was made to face the ITO film adhered surface, and the glass with ITO adhered to both surfaces was sandwiched between them. The plates were bonded to each other through a spacer of 10 m to form a cell, and a nematic liquid crystal composition (GR-63 manufactured by Chisso Corporation) was enclosed between the glasses to manufacture a liquid crystal shutter device.

This device did not appear opaque when looking at the letters of the newspaper through the glass surface, but it became transparent by applying an AC voltage of 100 _HZ and 10 V between both transparent electrodes, and the letters could be read. It was found that the switching effect of light can be obtained by applying a voltage. The contrast ratio at this time was 1: 2.0.

Comparative example 2

An apparatus was prepared in the same manner as in Example 2 except that the same flat glass as in Example 2 was subjected to the orientation treatment by a rubbing method in which one side was rubbed with a cloth in one direction. O When I read the letters of the newspaper through the glass surface of this device, the letters were transparent and readable. Even when applied between both transparent electrodes in the same manner as in Example 2, there was no change and it was transparent, and the effect of optical switching was not obtained.

Example 3

An 8 ^ thick polyimide film (PSI-G-4630 manufactured by Chisso Corp.) was formed on a commercially available ITO film-coated glass electrode plate, and then the polyimide film was coated with a film of 50%. 'Nash's power was randomly rubbed with Borundum and processed into random irregularities. Similarly, a glass substrate having electrodes (ITO films) on both sides was subjected to the same treatment to prepare an electrode plate having random uneven surfaces on both sides.

Of these glass electrode plates, the ITO film-attached surfaces of the glass electrode plate with the ITO film attached on one side should face each other, and one glass electrode plate with ITO attached on both sides should be placed in the middle. A cell was prepared by laminating it through a m-spacer, and a nematic liquid crystal composition (GR-63 manufactured by Chisso Corporation) was enclosed between these glass electrode plates to prepare a liquid crystal shutter device.

This device is opaque and invisible when looking at the characters of Shin Feng through the glass surface, and becomes transparent by applying an AC voltage of 100 Hz and 15 V between both transparent electrodes. And the switching effect of light was obtained by applying a voltage. The contrast ratio at this time was 1: 2.0.

Comparative example 3

A flat glass plate similar to that of Example 3 was subjected to orientation treatment by a rubbing method in which one surface was rubbed in one direction with a cloth, and the other devices were produced in the same manner as in Example 3. When the letters on the newspaper were seen through the glass surface of this device, the letters were transparent and readable. Even when applied between both transparent electrodes in the same manner as in Example 3, there was no change and it was transparent, and the effect of optical switching was not obtained.

Example 4

Glass plate with hydrofluoric acid to a width of 1 cm and depth 5 // 10 mountain-shaped grooves _g

A transparent electrode was formed by attaching an ITO film to the grooved side of the glass plate formed by etching with a scatterer.

The two glass plates were attached to each other with a spacer of 10 / m so that the ITO film adhering surfaces face each other, with the grooves parallel to each other to form a cell, and a nematic glass plate was placed between the two glass plates. A liquid crystal shutter device was prepared by enclosing a liquid crystal composition (GR-63 manufactured by Chisso Corporation). This device did not appear opaque when looking at the letters of Shin Feng through the glass surface, but it became transparent by applying an AC voltage of 100 Hz and 10 V © between both transparent electrodes, and the letters were read. It was possible to obtain a light switching effect by applying a voltage. The contrast ratio at this time was 1: 1.7.

The same effect was also obtained by applying a voltage by applying nematic liquid crystal in the same manner as in the case where cells were made by shifting the groove by 5 to 90 °.

Example 5

In Example 1, the thickness of the cell was set to 15 ^, and a ferroelectric liquid crystal composition (Cs-1 0 1 1 manufactured by Chisso Corporation) was filled. When a pulse of 20 V of soil for 5 msec was applied to this cell, the letters on the new paper on the bottom disappeared.

As a comparison, when a transparent cell with parallel orientation was used and the same experiment was performed, the characters were not completely invisible. Industrial availability

Unlike the conventional device, the liquid crystal shutter device of the present invention does not need to attach a polarizing element, does not require a special alignment treatment of the glass substrate, consumes the same power as the conventional TN type system, and utilizes the amount of light. Efficiency is improved.

The shutter device of the present invention is used as a light transmission type and a light reflection type light shutter device, for example, a light shielding plate for a welding mask, a door mirror, a shutter for an optical printer, an electro-optical diaphragm, a diffuser plate for a strobe light, a reduction plate. It can be applied to optical filters and the like.

Claims

Ί 1 Request range

1. Two or more transparent substrates, each of which is essentially transparent and has not been oriented, are stacked, and a nematic liquid crystal is sealed between them by a spacer, A liquid crystal shirt device that consists of a cell in which a transparent electrode is attached to the top of a stacked transparent substrate and a transparent electrode or an opaque electrode is attached to the bottom. The liquid crystal shutter according to claim 1, wherein the transparent electrode is an active element.

3. Two or more transparent substrates, each made of a material that is essentially transparent and having one or more inner surfaces roughened, are stacked and a spacer is placed between them. A nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, a ferroelectric liquid crystal and an antiferroelectric liquid crystal are encapsulated in a disordered alignment state, and a transparent electrode is stacked on top of the transparent substrate in this way. , And a liquid crystal shutter device consisting of cells with transparent or non-transparent electrodes attached to the bottom.

4. Claim that the surface-roughened transparent substrate is a result of cutting or etching with 0.5 to 100 depths and line widths of 0.5 to 100 0 regular or irregular grooves. LCD shutter described in Range 3

5. A liquid crystal shirt according to claim 3, wherein a transparent resin film is formed on the surface of the transparent substrate in contact with the liquid crystal, and the surface is roughened. The transparent electrode is an active element. 5. The liquid crystal shutter device described in 5.