JPH06301005A - Screen - Google Patents

Abstract

PURPOSE:To provide a screen which is easily visible even in a bright place. CONSTITUTION:This screen has a structure formed by holding a layer consisting of a high polymer 108 and a liquid crystal 109 with two sheets of transparent substrates 101, 107 formed with transparent electrodes. The high polymer 108 orients in a specific direction. Only the light polarized in the orientation direction scatters when the screen is irradiated with polarized light by a projector at the time of impressing an electric field. Videos having a high contrast are thus displayed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a screen for displaying an image of a projector.

[0002]

2. Description of the Related Art A conventional screen is disclosed in, for example, Japanese Patent Laid-Open No.
No. 04-212927, JP-A No. 04-220620, and JP-A No. 04-349426, a structure in which a liquid crystal layer made of a polymer and a liquid crystal having a refractive index anisotropy is sandwiched between two substrates having electrodes formed thereon. It consists of In the liquid crystal layer, the polymer and the liquid crystal are in a phase-separated state, and the ordinary refractive index of the liquid crystal and the refractive index of the polymer have the same relationship. When no electric field is applied between the substrates, the liquid crystal is randomly oriented, and the refractive index is different at the boundary between the polymer and the liquid crystal, so that the light incident on the light control layer is scattered. When an electric field is applied between the substrates, the liquid crystal is oriented in the direction of the electric field, and the refractive index of the liquid crystal and the refractive index of the polymer with respect to the light incident in the direction parallel to the electric field are equal, so that the liquid crystal becomes transparent. By utilizing this phenomenon, there are some which are used as a screen and an advertising board when no electric field is applied and used as a window when an electric field is applied.

As a screen not using liquid crystal, in addition to a commonly used white cloth, a polarizing plate is attached to a white cloth in a direction in which the polarization direction of the projector and the transmission axis of the polarizing plate are aligned. In some cases, the contrast of the projected image was improved.

[0004]

However, since a screen using a conventional liquid crystal becomes transparent when a voltage is applied,
Even when it was not used as a screen, the transparent state could not be maintained unless power was constantly supplied. Further, there is a problem that the contrast of the projected image is deteriorated in a bright place and it is very difficult to see.

On a screen that does not use liquid crystal, polarized light from the projector first passes through a polarizing plate attached to the screen, then is scattered by a white cloth, and passes through the polarizing plate again for observation. However, there is a problem in that the polarization direction changes when scattered by the cloth, and the light that is not parallel to the transmission axis of the polarizing plate is absorbed by the polarizing plate, resulting in a loss of light quantity. The present invention solves such a problem, and an object thereof is to provide a high-performance screen by a simple means.

[0006]

The screen of the present invention comprises:
In a screen made of a polymer and a liquid crystal, which is sandwiched between two substrates having electrodes formed thereon, the polymer is oriented.

Further, the polymer is characterized in that it is oriented in a granular form in the liquid crystal.

Further, the polymer is characterized in that it forms an aligned network in the liquid crystal.

Further, the liquid crystal is characterized in that it is oriented in a capsule shape in the polymer.

Further, in the screen, a polarizing plate is provided on one surface of the substrate on which no electrode is formed.

Further, in the screen, a polarizing plate and a reflecting plate are provided on one surface of the substrate on which the electrodes are not formed.

[0012]

The details of the present invention will be described below with reference to Examples.

(Embodiment 1) FIG. 1 shows the structure of the screen of the present invention.

Transparent electrodes 102 and 106 of ITO are formed on one side of transparent substrates 101 and 107 made of glass, and alignment films 103 and 105 of polyimide are applied and baked on the transparent electrodes 102 and 106, and rubbed in one direction with a cloth. Next, two substrates are stacked so that the rubbing directions are parallel to each other, and the substrates are fixed with a gap of about 5 μm between them, and a liquid crystal having refractive index anisotropy (BL-007 manufactured by Merck) in the gap between the substrates. , A liquid crystal mixture consisting of a polymer precursor, biphenyl methacrylate, was encapsulated. The liquid crystal and polymerized polymer both have refractive index anisotropy, and the refractive index for ordinary light and the refractive index for extraordinary light are selected to be similar values. The liquid crystal mixture contains 10 parts of biphenyl methacrylate with respect to the liquid crystal.
It was made to be wt%. The enclosed liquid crystal is aligned according to the alignment treatment applied to the substrate.

The alignment treatment is not limited to the method of rubbing the polyimide alignment film as long as the liquid crystal is aligned in parallel, and may be the method of oblique vapor deposition or the method of directly rubbing the electrodes or the substrate.

Next, when the liquid crystal panel is irradiated with ultraviolet rays to polymerize the polymer precursor, it becomes a polymer 108 having optical anisotropy and is dispersed in the liquid crystal 109 in a phase-separated state.

The operating principle of the liquid crystal panel thus manufactured is shown in FIG. When a voltage is applied between the substrates, the liquid crystal molecules are aligned in the direction of the electric field, but the polymer remains. Therefore, the refractive index for light polarized in the rubbing direction differs between the polymer and the liquid crystal, and the light is scattered at the boundary between the polymer and the liquid crystal. For light polarized perpendicular to the rubbing direction, there is no difference in refractive index between the polymer and the liquid crystal, so the light is transmitted as it is.

When no voltage is applied between the substrates, both the liquid crystal and the polymer are aligned in the rubbing direction. Since the liquid crystal and the polymer have similar refractive indices, light is transmitted regardless of the polarization direction.

FIG. 3 shows the configuration when the liquid crystal panel is used as a screen. A liquid crystal panel of twist alignment type was used for the projector 301. In this case, since the liquid crystal panel has a polarizing plate, the emitted light is linearly polarized light. If the light emitted from the projector is not linearly polarized,
A polarizing plate is arranged between the projector 301 and the screen 302 so that the screen is irradiated with linearly polarized light. The polarization axis of the screen or the polarizing plate of the projector is arranged so that the rubbing direction of the screen and the polarization direction of the light of the projector are the same. When a voltage is applied between the substrates of the liquid crystal panel used as a screen, the liquid crystal panel becomes clouded, and all the light from the projected projector is scattered on the screen to display an image.

When the surroundings of the screen are bright, most of the noise light is scattered on the screen and becomes difficult to see on a screen using a normal white cloth, but when the screen of the present invention is used, it is randomly polarized around the surroundings. More than half of the noise light can be transmitted without being scattered.
In FIG. 3, the polarization direction of light when viewed from the projector side is shown by an arrow surrounded by a circle. Therefore, by placing black paper on the back side of the screen to absorb the light transmitted through the screen, the amount of noise light returning to the observer side is reduced, and the contrast of the reproduced image can be increased, making it very easy to see. Video was obtained.

(Embodiment 2) FIG. 4 shows the configuration of another embodiment of the present invention.

Orientation processing is performed on the glass transparent substrates 401 and 405 on which the ITO transparent electrodes 402 and 404 are formed. Next, the two substrates are stacked so that the orientation directions of the substrates are parallel to each other, and the substrates are fixed with a distance of 5 μm between them.
Liquid crystal with refractive index anisotropy in the gap between substrates (Merck BL
-007) and diacrylate (B
A liquid crystal mixture consisting of 5 wt% of C6H manufactured by DH and 1 wt% of a photopolymerization initiator (Irgacure 651 manufactured by Ciba-Geigy) is sealed.

Next, when the liquid crystal mixture is irradiated with ultraviolet rays to be polymerized, the liquid crystal and the polymer are phase-separated, and the polymer 406 spreads in the liquid crystal 407 in a three-dimensional network. Here, since the substrate is subjected to the alignment treatment, the network structure of the polymer is not isotropic and becomes elongated in the direction of the alignment treatment. Since the liquid crystal is aligned along the polymer when no electric field is applied, the liquid crystal is generally aligned in the direction of the alignment treatment. It is selected so that the refractive index of extraordinary light of liquid crystal and the refractive index of polymer are close to each other. Then, in the state in which no voltage is applied, the polymer and the liquid crystal have a close refractive index, and thus the state becomes transparent. Next, when a voltage is applied, the liquid crystal aligns in the direction of the electric field. Then, among the lights incident on the liquid crystal panel, a difference occurs in the refractive index of the liquid crystal and the polymer with respect to the light polarized in the rubbing direction, and the light is scattered at the boundary between the liquid crystal and the polymer. Light polarized perpendicular to the rubbing direction is transmitted as it is.

Then, it is absorbed by a black paper on the back side of the screen. Thus, when the liquid crystal panel was irradiated with linearly polarized light parallel to the rubbing direction with the projector as in the case of Example 1, a high-contrast image was displayed.

(Embodiment 3) FIG. 5 shows the configuration of a third embodiment of the present invention.

Glass transparent substrates 501 and 505 on which ITO transparent electrodes 502 and 504 are formed are stacked in parallel, and the substrates are separated by a distance of about 5 μm. E7 manufactured by E.) and an epoxy resin having the same refractive index anisotropy (M manufactured by Wilmington Chemicals)
K107 and BP-10 are mixed 1: 1)
Cure with heat cure. Next, when the glass is displaced in parallel (shearing), the liquid crystal and the polymer are phase-separated, and the liquid crystal is dispersed in the polymer in the form of capsules.
Here, the liquid crystal capsules are aligned in a direction in which the glass is displaced by shearing. The polymers are also oriented in the same direction. Since the liquid crystal is aligned along the surface of the capsule when no electric field is applied, the liquid crystal is generally aligned in the shearing direction. The liquid crystal and the polymer are selected so that the refractive index for ordinary light and the refractive index for extraordinary light have similar values.

Therefore, when no voltage is applied, the polymer and the liquid crystal are in a transparent state because their refractive indices are close to each other. When a voltage is applied, the liquid crystal aligns in the direction of the electric field inside the capsule. Since the orientation of the polymer remains the same, there is a difference in the refractive index of the liquid crystal and the polymer with respect to the light polarized in the shearing direction among the light incident on the liquid crystal panel, and the light is scattered at the boundary between the liquid crystal and the polymer. Wake up. Light polarized perpendicular to the shearing direction is transmitted as it is. Thus, as in Examples 1 and 2, when the liquid crystal panel was irradiated with light polarized in the orientation direction of the polymer by the projector, a high-contrast image was displayed.

As described above, the liquid crystal panel used for the screen of the present invention is characterized in that it has a function of scattering only the polarized component in a specific direction out of the light incident on the liquid crystal panel, and therefore the material of the transparent substrate, the liquid crystal. The material, the polymer material, the mixing ratio, the structure of the liquid crystal panel, and the manufacturing method are not limited to those described above and may have the same functions.

(Embodiment 4) FIG. 6 shows the configuration of a fourth embodiment of the present invention.

It has a construction in which a polarizing plate 603 is attached to the back side of the screen 602 which is the same as the construction of the first or second embodiment.

The transmission axis of the polarizing plate is made parallel to the direction of alignment treatment of the liquid crystal panel used for the screen. When a voltage is applied between the substrates of the liquid crystal panel to be used as a screen, ambient noise light is absorbed by the polarizing plate on the back side of the screen even if it passes through the screen.
And the same function as the black paper used in Example 2. When no voltage is applied, it is the same as when a polarizing plate is attached to glass, so that the back side of the screen can be seen through and has a function as a window.

(Fifth Embodiment) FIG. 7 shows the configuration of a fifth embodiment of the present invention.

A polarizing plate 703 and a reflecting plate 704 are provided on the back side of the screen 702 having the same structure as in the first or second embodiment.
Is provided. As in the case of Example 4, the transmission axis of the polarizing plate is made parallel to the direction of alignment treatment of the liquid crystal panel used for the screen. By doing so, the polarizing plate has a function of absorbing ambient noise light transmitted through the screen. In this configuration, a reflector made of Al is further attached to the back side of the polarizing plate. The light emitted from the projector that illuminates the screen is scattered on the screen, but naturally also on the back side of the screen. By reflecting this light again to the observer side with the reflector, the light utilization efficiency can be increased and a bright image can be displayed. Further, the light incident on the screen when no electric field is applied is reflected by the reflection plate and can be used as a mirror.

Although the embodiments of the present invention have been described above, the screen of the present invention is usually used for partitioning windows and rooms,
It can be used as a mirror and as a screen when necessary. It can also be widely applied to advertising boards, curtains, show windows, etc.

[0035]

According to the present invention, the following effects can be obtained.

(1) Since noise light from the surroundings scattered on the screen is reduced, a high-contrast image can be obtained even in a bright place.

(2) Even when not used as a screen,
It can be used as a window, billboard, or mirror.

(3) It is economical because it is not necessary to supply electric power when it is not used as a screen.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a screen of the present invention.

FIG. 2 is a diagram showing the operating principle of the screen of the present invention. (A) The figure which shows a mode when an electric field is not applied. (B) The figure which shows a mode when an electric field is applied.

FIG. 3 is a diagram showing a configuration for projecting an image on a screen of the present invention.

FIG. 4 is a side view showing another configuration of the screen of the present invention. (A) The figure which shows a mode when an electric field is not applied. (B) The figure which shows a mode when an electric field is applied.

FIG. 5 is a side view showing a configuration of a screen according to a third embodiment of the present invention. (A) The figure which shows a mode when an electric field is not applied. (B) The figure which shows a mode when an electric field is applied.

FIG. 6 is a side view showing a configuration of a screen according to a fourth embodiment of the present invention.

FIG. 7 is a side view showing a configuration of a screen according to a fifth embodiment of the present invention.

[Explanation of symbols]

 101, 107 Substrate 102, 106 Electrode 103, 105 Alignment film 104 Liquid crystal layer 108 Polymer 109 Liquid crystal 201, 207 Substrate 202, 206 Electrode 203, 205 Alignment film 204 Liquid crystal layer 208 Polymer 209 Liquid crystal 301 Projector 302 Screen 303 Noise light 401, 405 Substrate 402, 404 Electrode 403 Liquid crystal layer 406 Polymer 407 Liquid crystal 501, 505 Substrate 502, 504 Electrode 503 Liquid crystal layer 506 Liquid crystal 507 Polymer 601 Projector 602 Screen 603 Polarizing plate 701 Projector 702 Screen 703 Polarizing plate 704 Reflection Board

Claims (6)

[Claims] 1. A screen composed of a polymer and a liquid crystal, which is sandwiched between two substrates having electrodes formed thereon, wherein the polymer is oriented. 2. The screen according to claim 1, wherein the polymer is oriented in a granular form in the liquid crystal. 3. The screen according to claim 1, wherein the polymer forms an oriented network in the liquid crystal. 4. The screen according to claim 1, wherein the liquid crystal is oriented in a capsule shape in the polymer. 5. The screen according to claim 1, wherein the screen is provided with a polarizing plate on one surface of the substrate on which no electrode is formed. 6. The screen according to claim 1, further comprising a polarizing plate and a reflecting plate on one surface of the substrate on which no electrode is formed.