JPH0675303A - Reflection-type screen having recurrent reflection property - Google Patents

Abstract

PURPOSE:To obtain a bright projected image by successively forming a light diffusion layer, polarizing filter layer, transparent lead layer having focusing property of light, and light reflecting layer. CONSTITUTION:This reflection-type screen consists of, from the upper surface, a light diffusing layer 1, polarizing filter layer 2, transparent bead layer 3, and reflecting layer 4. The light diffusion layer is a resin film having an embossed surface or a mat coating, and transparent thermoplastic resin such as oriented polypropylene (OPP), vinyl chloride, and polyethylene terephthalate (PET) are used for this layer. The polarizing filter layer 2 is, for example, polyvinylalcohol film with adsorption of iodine is used. By impregnating a polyvinylalcohol film with an alcohol soln. of iodine, and then orienting, crystal of iodine is uniformly adsorbed regularily in one direction, and this crystal acts as the polarizing transmission axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type screen suitable for viewing a projected image of a liquid crystal projector, and more particularly, it is hardly affected by room lighting or external light from a window in a bright room. The present invention relates to a reflective screen having a retroreflectivity capable of obtaining a bright projected image and having a small difference in brightness between the central portion and the peripheral portion of the screen.

[0002]

2. Description of the Related Art Normally, when a liquid crystal projector projects an image, a reflection type screen having a white surface is used, but as a device for realizing a bright projection screen in a bright room, a polarizing plate is used for the screen. It has been conventionally used to selectively transmit and reflect only light from a liquid crystal projector. This is because the light from the liquid crystal projector has a polarization property when it passes through the liquid crystal panel. Therefore, by matching the polarization transmission axis of the polarizing plate of the screen with this polarization axis, almost 100% of the light from the liquid crystal projector is close. Can be transmitted and reflected. On the other hand, indoor illumination and external light from windows are absorbed more than half by the polarizing plate of the screen, and the reflection is reduced to realize the relative brightness of the screen.

[0003]

However, in such a conventional reflection type screen, there may be a difference in brightness between the central portion and the peripheral portion of the screen. Currently, floor-standing type liquid crystal projectors are the mainstream, but since the light emitted from the projector is incident almost vertically on the screen at the center of the screen, the reflected light will be reflected when the observer is near the projector. Is returned toward the observer, whereas light from the projector is reflected toward the outside of the screen in the peripheral portion of the screen, and it is difficult to return to the direction of the observer. That is, it is inferior in retroreflectivity.

Although it is effective to process the screen into a concave shape in order to provide it with retroreflective properties, it is difficult to process it in a large size and there is a problem in terms of storage.

The present invention has been made in view of the above-described conventional problems, and even in a bright room, a bright projected image can be obtained with almost no influence of room illumination or external light from a window, and the central portion of the screen is obtained. An object of the present invention is to provide a reflection type screen having a small difference in brightness between the surrounding area and the surrounding area.

[0006]

In order to solve the above problems, the reflection type screen of the present invention comprises a light diffusing layer, a polarizing filter layer, a transparent bead layer having a light converging property, and a light reflecting layer in that order. It is configured as follows.

The structure of the present invention will be described in more detail below.

FIG. 1 is a sectional view showing the construction of an embodiment of the reflection type screen of the present invention.

As is apparent from FIG. 1, the reflection type screen of this embodiment comprises a light diffusing layer 1, a polarizing filter layer 2, a transparent bead layer 3 and a light reflecting layer 4 which are sequentially laminated from the top.

The light diffusion layer 1 is a resin film whose surface is embossed or mat-coated, and is made of oriented polypropylene (OPP), vinyl chloride, polyethylene terephthalate (PET), triacetyl cellulose (TAC).
A transparent thermoplastic resin such as is used.

For the polarizing filter layer 2, for example, a polyvinyl alcohol film having iodine adsorbed thereon is used. When the polyvinyl alcohol film is immersed in an iodine alcohol solution and then stretched, iodine crystals are regularly and uniformly adsorbed in one direction, and the crystals serve as a polarization transmission axis. The polarization filter layer 2 is arranged in the direction of polarization of light from a liquid crystal projector having a polarization property.
It is necessary to provide them so that the polarization transmission axes of are matched.

As a result, almost 100% of the light from the liquid crystal projector having a polarization property is transmitted and reflected by the polarization filter layer 2, but more than half of the room illumination and the extraneous light from the window are emitted. Is absorbed and the reflected light is reduced, so that a bright projected image can be obtained even in a bright room with almost no influence of indoor lighting or external light.

The transparent bead layer 3 is formed by arranging transparent beads 5 having a light converging property on one surface, and a transparent resin 6 such as an acrylic resin or a urethane resin is used to fix the transparent beads 5.

According to this structure, the incident light having passed through the polarization filter layer 2 passes through the transparent beads 5 having a light converging property, and the incident light of the light reflection layer 4 formed so as to coincide with the focal plane of the transparent beads 5. The light will be reflected by the reflecting surface, and will pass through the transparent beads 5 again and go out in the incident direction. Therefore,
Since the reflected light in the peripheral part of the screen is not specular reflection but returns in the incident direction of light, so-called retroreflection, the light in the peripheral part of the screen efficiently returns to the observer in the peripheral part of the projector, and the central part of the screen It is possible to obtain a projected image of uniform brightness with little difference in brightness in the peripheral area.

It is possible to change the degree of retroreflection by changing the refractive index of the transparent beads 5. In the present invention, it is desirable to use transparent beads having a refractive index in the range of 1.5 to 2.2. Further, it is desirable that the transparent beads have a particle size of about 50 to 150 μm.

By providing the light reflection layer 4 under the transparent bead layer 3, it is possible to further improve the reflection efficiency.
In this case, the light reflection layer 4 must be formed so that its reflection surface coincides with the focal plane of the transparent beads 5.
For that purpose, the thickness of the transparent resin 6 interposed between the transparent beads 5 and the light reflection layer 4 may be adjusted. Such a light reflection layer 4 is formed of, for example, an aluminum foil, an aluminum plate,
It can be formed by using aluminum powder, pearl pigment, etc. in addition to the aluminum vapor deposition film.

FIG. 2 is a sectional view showing the construction of another embodiment of the reflection type screen of the present invention.

That is, a transparent resin layer 6 provided on the back surface of the polarizing filter layer 2 is fixed in a state in which a part of the transparent beads 5 are buried and fixed, and the exposed portions of the transparent beads 5 are made of metal such as aluminum. The light reflection layer 7 is formed by vapor deposition.

The position of the focal plane of the transparent bead 5 differs depending on its refractive index. For example, when a transparent bead having a focal point at a position slightly apart from the back surface of the transparent bead is used, the configuration as shown in FIG. 1 can be adopted, but the back surface of the transparent bead has a focal plane due to the refractive index. When such transparent beads are used, the structure shown in FIG. 2 can be adopted.

[0020]

EXAMPLES The present invention will be described in more detail below with reference to examples.

A polypropylene film having a matte surface was used as a light diffusion layer, and a transmission type polarizing film NPF-1100H (manufactured by Nitto Denko Corporation) was used as a polarizing filter layer, which was laminated with the above polypropylene film. As the transparent bead layer provided next to the polarizing filter layer, spherical transparent beads having a refractive index of 1.92 and an average particle diameter of 60 microns were used, and the transparent beads were half-embedded in the transparent resin layer coated on the back surface of the polarizing filter layer. After laying in one layer in this state, the exposed hemispheres of the transparent beads were vacuum-deposited with aluminum to produce a reflective screen.

When a liquid crystal projector HV-100 (manufactured by Sharp Corp.) was used to perform projection using this screen, a bright projected image was obtained with almost no influence of room lighting or the like. The brightness of the room at this time
It was 100 lux, and it was an environment in which sufficient images could not be obtained on a normal screen, but on the screen of this example, the images were sufficiently observable. Further, in the case of the screen using the above-mentioned conventional polarizing plate, the ratio of the reflection brightness between the central part and the peripheral part of the screen is
Although it was about 100: 10, in the screen of this embodiment, the ratio of the reflection luminance between the central portion and the peripheral portion can be made uniform to 100: 55, and a projected image with a small difference in brightness as a whole can be obtained. Was obtained.

[0023]

As described in detail above, according to the reflection type screen of the present invention, a light diffusing layer, a polarizing filter layer, a transparent bead layer having a light converging property, and a light reflecting layer are sequentially provided. As a result, even if projection is performed by a liquid crystal projector in a bright room, it is possible to obtain a bright projected image with almost no influence of indoor lighting or external light from a window. Moreover, the reflection type screen of the present invention has a retroreflective property, and it is possible to obtain a projected image with a small difference in brightness between the central portion and the peripheral portion of the screen.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a reflective screen of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of another embodiment of the reflection type screen of the present invention.

[Explanation of symbols]

 1 Light Diffusing Layer 2 Polarizing Filter Layer 3 Transparent Bead Layer 4 Light Reflecting Layer 5 Transparent Beads 6 Transparent Resin 7 Light Reflecting Layer

Front page continued (72) Inventor Tsutomu Yoshida 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (1)

[Claims] 1. A retroreflective reflective screen comprising a light diffusing layer, a polarizing filter layer, a transparent bead layer having a light converging property, and a light reflecting layer, which are sequentially provided.