JPH06123920A - Reflection type projection screen - Google Patents

Abstract

PURPOSE:To provide a reflection type projection screen which diffuses light in a specified range and uniformly diffuses light in this specified range by successively laminating a specified reflecting sheet and a plastic light-diffusing sheet on a base sheet. CONSTITUTION:This screen consists of a base sheet 1 and a reflecting sheet 3, and a plastic light diffusing sheet 4A successively laminated on each other. The reflecting sheet 3 consists of a plastic Fresnel lens and a reflecting layer 2 formed on the surface of the lens. The light diffusing sheet 4A may be brought into tight contact with the reflecting sheet 2 on the Fresnel lens. By providing the reflecting sheet 3 having focusing function by providing a reflecting layer on the Fresnel lens between the reflecting layer 2 and the light diffusing sheet 4, a reflectance is improved and further diffusion of light can be limited in a specified range. In this range, a bright and sharp image can be obtd. The diffusion range of light can be determined by combination of focusing function and diffusing function. By properly selecting the combination, desired projection screen performance can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection screen for receiving an image projected from a projection device, and more particularly to a reflection type projection screen for a liquid crystal projector.

[0002]

2. Description of the Related Art Generally, a screen used for projection of slides or OHP, or projection of a movie or a video is a film of vinyl chloride resin lined with a dark sheet and coated or laminated with aluminum powder or glass beads. Is. Since the conventional screen has a low reflectance and the image is dark, the image cannot be viewed unless the room is darkened.

As a reflection type screen, for example, vinyl chloride obtained by mixing a gold pigment, a silver pigment or a pearl pigment on a vinyl chloride resin layer of an ordinary vinyl wallpaper as described in JP-B-63-67474. A vinyl wallpaper with a high surface reflectance that was applied was also used by sticking it to the wall surface. However, this also does not have sufficient reflectance and diffusion performance.

In recent years, a liquid crystal projector has appeared and is becoming popular as a means for displaying a clear image on a large screen. Including those used for LCD projectors,
The projection screen is required to have high brightness, that is, high reflectance of light, and good diffusion performance, that is, capable of uniformly diffusing light.

As a screen that meets this demand, there is known a screen in which an adhesive is applied to a sheet of plastic or the like, and glass beads having a small diameter are arranged on the sheet so as to be closely packed. However, this screen has a small reflection angle, and the visible area is narrow. Also, due to its structure,
The beads are likely to fall off, and dust is likely to collect on the surface, making them impractical. In particular, when this kind of material is used as a roll-up type screen, there is also a problem that the glass beads gradually drop off while the screen is rolled and unfolded many times.

As a projection screen which has solved the above problems, the applicant has already proposed a projection screen (transmissive type and reflective type) having a coating film of a paint containing calcite powder as a diffusion layer on the surface ( JP-A-4-53945).
Subsequently, the applicant disclosed a reflection type projection screen in which a polyester film having a metal vapor deposition layer on a base cloth and a translucent polyvinyl chloride film containing a bright pigment were laminated (Saikaihei 4- 50842).

Since both of the above projection screens have high brightness and high diffusibility, images can be viewed in a wide range, but the performance is only to diffuse light. However, since the position of the viewer of the projection screen is limited to a certain range, it is preferable that the diffusion direction of light is limited to a certain range and that the light diffuses uniformly within that range. Therefore, it is better to provide the projection screen with a function of concentrating light.

Based on such an idea, the inventor
As a reflective projection screen having a light collecting function, a reflective projection screen in which a reflective layer, a Fresnel lens sheet made of plastic, and a light diffusing layer are sequentially provided on a substrate was invented, and this was also proposed. Kaihei 4-20472
2].

As a result of further research, when a reflection sheet having a reflection layer on the surface of the Fresnel lens is used instead of the Fresnel lens sheet, a reflection type projection sheet having higher reflectance can be obtained. Found.

[0010]

SUMMARY OF THE INVENTION Based on this new finding, an object of the present invention is to improve a reflection type projection screen which diffuses light only within a predetermined range and uniformly diffuses within the range. To provide.

[0011]

As shown in FIG. 1, the reflection type projection screen of the present invention has a reflection layer on the surface of a plastic sheet Fresnel lens on a substrate sheet (1).
The reflection sheet (3) provided with (2) and the light diffusion sheet (4A) made of plastic are sequentially stacked.

As shown in FIG. 2, the light diffusion sheet may be in the form of being in close contact with the reflection sheet (2) on the Fresnel lens.

The substrate sheet is a glass fiber or plastic film, specifically, polyester, polycarbonate, polyimide, polyarylate, polyether ether.
A film having good dimensional stability, such as terketone or cellulose acetate, is suitable. The base sheet is required to have the function of increasing the dimensional stability of the screen, especially when used as a roll-up type screen, so that the drawn down screen does not sag. In addition, when the screen that has been rolled up and stored is used again for projection after being unfolded, the image is distorted if the curl remains, so that the base cloth is required to have sufficient elasticity and rigidity.

The most highly satisfying ones of these requirements are
It is a woven or non-woven fabric of glass fibers. Those impregnated with polyvinyl chloride melamine resin are easy to use.

The reflective layer may be formed of a metal vapor deposition layer or a glitter ink layer.

The vapor deposition layer can be formed of a metal having a high reflectance such as aluminum, silver or chromium. Vapor layer thickness is 1
If it is about 0 to 50Å, it does not transmit light and functions as a reflection layer. The vapor deposition may be performed by a known method such as a vacuum vapor deposition method or a sputtering method.

The following are examples of glitter pigments used in glitter ink. (A) What is called a pearl pigment, specifically, those obtained by crushing the inner portion of shellfish and pearls, mica, mica fine particles baked with TiO ₂ or iron oxide, (b) metal powder, specifically Is copper,
Fine particles of aluminum, brass, bronze, gold, silver, etc., preferably 1 to 120 μm, (c) metal vapor deposited plastic film fragments, such as polyethylene terephthalate film, with the above metal, usually aluminum vapor deposited, Crushed.

The Fresnel lens sheet having a reflective layer on the surface thereof as a reflective sheet can be typically manufactured by press-molding an acrylic resin plate, but when used as a roll-up screen, it is made of plastic. It is preferable to use a lens sheet (3) in which a Fresnel lens pattern is formed on a support sheet (31) with a flexible plastic.

Such a lens sheet can be obtained, for example, by a method called "drum printing system" disclosed in Japanese Patent Laid-Open No. 64-6935. This manufacturing method uses a printing drum provided with concave portions of a predetermined pattern, and at least the concave portions are filled with a resin that is cured by ultraviolet rays or electron beams, and then the support sheet is wound around the drum and irradiated with ultraviolet rays or electron beams. Alternatively, heat is applied to cure the resin and the resin is attached to the support sheet, and the support sheet is peeled off from the drum. others,
There is also a technique described in JP-B-46-12913, in which a thermoplastic resin is used or a thermosetting resin is used after being cured.

The cured resin layer must be transparent and must be formed of a soft and flexible material to be used for a screen of a rolled-up type. For example, some urethane, acrylic, and polyester ultraviolet (or electron beam) curable resins satisfy this condition. A small amount of thermoplastic resin may be added to them. The material of the support sheet is not particularly limited,
It is preferable to use a transparent sheet made of polyurethane, elastomer, polyvinyl chloride, or the like, to which a curable resin for pattern printing adheres well.

The shape of the lens is determined according to the range in which light should be diffused and concentrated. There are ring-type and line-type Fresnel lenses, both of which are projection screens.
However, it is generally desirable for the projection screen to suppress vertical diffusion and widen lateral diffusion, and it is appropriate to use an elliptical lens in landscape orientation.

The plastic light-diffusing sheet may be a sheet prepared by kneading light-diffusing material powder into plastic, or may be formed by applying a coating material in which the light-diffusing material powder is dispersed using an appropriate plastic as a vehicle. You may.
Of course, the paint may be applied to a plastic sheet. The plastic used for the sheet is arbitrary such as polyethylene, polystyrene, acrylic resin, vinyl chloride resin, and elastomers. It goes without saying that when the projection screen is a roll-up type, the light diffusion sheet should have flexibility.

As the light diffusing material, powders of calcium carbonate, silica, glass beads, urethane beads, barium carbonate and the like can be used, but calcite powder is most suitable in terms of the balance between light diffusivity and transparency. .

The calcite powder has an average particle size of 2 to 20 μm.
It is preferable that the particle size distribution is as narrow as possible. For example, if the average particle size is 5 μm, 80
The particle size distribution is such that weight% or more falls within the range of 3 to 7 μm.

When a coating material containing calcite powder is used, it comprises an appropriate vehicle such as vinyl chloride / vinyl acetate copolymer or urethane resin, and an appropriate solvent selected accordingly. Needless to say, it is preferable that the proportion of calcite powder in the paint is high, but if the proportion of vehicle is too low, it becomes difficult to form a coating film on the base sheet, so the composition of the paint is 100 parts by weight of calcite powder. For vehicle 10
The range of -100 to 100 parts by weight, particularly 10 to 50 parts by weight is preferable.

The coating of the paint on the lens sheet is performed by a known means such as roll coating, reverse coating, comma coating and die coating. Although the thickness of the coating film depends on the particle size of the calcite powder, it suffices if it is 10 μm or more in the dry state, and generally, a range up to 30 μm, for example, 15 μm is suitable.

A space is created between the diffusion layer and the lens sheet, except when the diffusion layer is formed by directly coating on the reflection layer of the Fresnel lens sheet. This space may be filled with a low refractive index material if desired.

The projection screen of the present invention may be used by directly adhering it to the glass of a wall or a window, or may be hung in a space by providing a hanging means, or can be erected at a desired position using a stand means. You may use it.
The projector (projector or the like) is preferably located between the spherical center of the Fresnel lens reflecting surface forming the concave mirror and the focal point.

[0029]

In the projection screen of the present invention, the reflection sheet (3) having a condensing function by providing the reflection layer on the surface of the Fresnel lens is provided between the reflection layer (2) and the light diffusion sheet (4). As a result, by increasing the reflectance and limiting the degree of light diffusion to a certain range, a bright and clear image was realized within that range.

Now, the light projected from the projector is incident on the diffusion layer and diffused there as shown in the upper part of FIG. 3. However, considering the straight-ahead component, it is refracted as seen in the middle part. It reaches the reflective layer, where it is reflected and collected to reach the diffusion layer. Therefore, as shown in the lower stage, the light is diffused in a certain range and emitted.

The light incident on the diffusion layer is first diffused and then diffused again at the time of emission. By combining this diffusion with the condensing function of the reflection sheet provided with the reflection layer on the surface of the Fresnel lens, Almost uniform light diffusion is achieved within a desired range. Since the extent to which this light is diffused is determined by a combination of the functions of light collection and diffusion, it will be readily understood that the proper projection of them will provide the desired projection screen performance.

FIG. 4 shows a screen gain chart of the projection screen of the present invention. For comparison, the known white screen and palle screen gain charts are also shown together. The white screen is a screen serving as a gain reference, and the peak gain is 1. The pulse screen is used in movie theaters where image quality is important, but it is mainly used for 35 mm projectors because of its low reflectance, and is not suitable for projectors. The projection screen of the present invention exhibits a reflectance higher than that of the pulse screen in the viewing angle range up to about ± 30 °.

FIG. 5 shows the details. As shown in FIG. 5, the viewing angle θ10% at which the gain is 10% lower than the peak gain Io (0.9 Io) is 1 on both sides.
It is 0 to 15 °, and the gain is reduced by 50% (0.5I
o) The viewing angle θ50% is 15 to 20 ° on the left and right.

In the roll-in type projection screen, some wrinkles may occur due to repetition of roll-in and roll-back, which may appear bright and dark. However, in the projection screen of the present invention, since the high screen gain is maintained over a wide viewing angle as described above, the inclination of the wrinkle portion with respect to the plane is within 20 °,
If it is preferably within 15 °, it does not appear as a difference in brightness.

[0035]

INDUSTRIAL APPLICABILITY The projection screen of the present invention diffuses light over a wider area than a conventional projection screen, but unlike a projection screen that is simply enhanced in diffusivity, it diffuses light to an unnecessary area. The uniform diffusion is performed within the required range as described above. As described above, the reflectance is high, and the light is bright without being wasted, and an image with good image quality can be seen within a certain range of angles with respect to the screen surface. Even if the screen has some wrinkles, it hardly affects the image.

Since the projection screen of the present invention can project a high quality image on a large screen, it can be used in combination with various projection means such as a liquid crystal projector. It withstands repeated involvement and deployment.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a reflective projection screen of the present invention.

FIG. 2 is a sectional view similar to FIG. 1, showing another example of the reflective projection screen of the present invention.

FIG. 3 is an enlarged view of a part of FIG. 1 for explaining the operation of the reflective projection screen of the present invention.

FIG. 4 is a chart showing the screen gain of the reflective projection screen of the present invention in comparison with that of a known projection screen.

5 is a detailed view of a portion of FIG.

[Explanation of symbols]

 1 Base Sheet 2 Reflective Layer 3 Reflective Sheet 31 Support Sheet 32 Cured Resin Layer 4A, 4B Light Diffusing Sheet

Claims (5)

[Claims] 1. A reflective projection screen comprising a base sheet and a plastic Fresnel lens on the surface of which a reflective layer is provided, and a plastic light diffusing sheet, which are sequentially stacked. 2. The reflection type projection screen according to claim 1, wherein the light diffusing sheet is a plastic sheet containing a light diffusing material powder or having a surface finely embossed. 3. The reflection according to claim 1 or 2, wherein both the base sheet reflection sheet and the light diffusion sheet are flexible so that the screen can be wound therein, and which has a suspending means or a stand means. Type projection screen. 4. The reflection type projection screen according to claim 1, wherein the reflection sheet and the light diffusing sheet are connected by an adhesive made of transparent plastic. 5. The reflective projection screen according to claim 1, which is used for projection by a liquid crystal projector.