JPH05297462A - Reflection type projection screen - Google Patents

Abstract

PURPOSE:To enable the assurance of bright images having a high contrast even in a bright place and to suppress the disturbance by stray light by providing a specific light diffusion layer on a base material having dark colors on both surfaces. CONSTITUTION:The light diffusion layer 1 made of a translucent plastic sheet kneaded with flaky bright pigments 2 is provided on the base material 3, both surfaces of which are colored to the dark color, for example, black, blackish brown or dark blue. Materials having rigidity, for example, metallic plates, such as iron plates and aluminum plates, wooden plates and plastic plates are used as the base material 3 if this screen is formed as a stationary type. A flexible sheet formed by laminating a base fabric 5 consisting of glass fibers and an intermediate sheet 6 which is the dark colored plastic sheet onto a lining sheet 4 which is the dark colored plastic sheet is used if the screen is formed as a winding type. Pearl pigments, such as mica, metallic powders of copper, aluminum, etc., and the splinters of the plastic films deposited with aluminum by evaporation are used as the bright pigments 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in reflective projection screens.

[0002]

2. Description of the Related Art As a projection screen, a lenticular lens sheet having a black stripe on the back has been known for a long time (Japanese Patent Publication No. 6-3591 and 46-3).
No. 708). Although this type of screen is visible even in bright places, it is expensive, difficult to wind up, and requires a large space for storage. In manufacturing, it is necessary to align the position of the lenticular lens and the black stripe with high precision,
It is technically difficult and the yield of non-defective products is low. For this reason,
There was no large projection screen suitable for home use.

As a projection screen which is cheap and easy to store, white polyvinyl chloride (PV
C) There is a roll-up screen in which films are laminated.
This type of conventional projection screen is so dark that it cannot be viewed without darkening the room.

With the spread of projection devices such as liquid crystal televisions and liquid crystal projectors, efforts have been made to realize clearer images, and various improved projection screens have been proposed. For example, in a screen composed of the above-mentioned dark-colored backing sheet and white PVC film, a metal vapor deposition layer is provided as a reflective layer on the white PVC film, and a semi-transparent P layer containing a pearl pigment thereon.
Laminated VC film (Actually developed 64-40835)
No.) or a dark surface on one side and a white surface on the other side, a printing layer of highly reflective ink is provided as a reflective layer on the white surface, and a glittering pigment or calcite powder is contained on it. There is a layer (Japanese Patent Application No. 3-143480) in which a semi-transparent plastic light diffusion layer is laminated.

All of these projection screens are screens intended to make an image clear by increasing the reflectance so that the image can be viewed even in a bright place. However, it was experienced that the desired result cannot be obtained only by increasing the reflectance. When these projection screens are used in a bright place, stray light other than the projection light interferes and the image is not so clear.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to secure a clear image with high contrast even in a bright place.
An object is to provide a reflection type projection screen that suppresses interference due to stray light.

[0007]

As shown in FIG. 1, the reflection type projection screen of the present invention has a scale-like glittering property on a substrate (3) which is dark on both sides, for example, black, black brown or dark blue. A light diffusion layer (1) made of a semitransparent plastic sheet in which the pigment (2) is kneaded is provided.

When the reflection type projection screen is fixed, a rigid material, for example, a metal plate such as an iron plate or an aluminum plate, a wood plate, or a plastic plate is used as the substrate.

On the other hand, in the case of the roll-up type, as shown in FIG. 1, as a base material (3), a glass fiber base cloth (5) is provided on a backing sheet (4) which is a dark-colored plastic sheet. It is preferable to use a flexible sheet in which the intermediate sheet (6) which is also a dark-colored plastic sheet is laminated.

The dark-colored plastic sheet may be a dark-colored pigment, for example, aniline black, carbon black, red grass mixed in, or solid-printed dark ink. The plastic used for the backing sheet and the intermediate sheet may be flexible, for example, polyvinyl chloride is a typical material, and in addition, polyolefin such as polypropylene and polyethylene, polyester such as polyethylene terephthalate,
Polystyrene, polycarbonate, acrylic resin, etc. are suitable. Particularly, 10 to 70 parts by weight, preferably 50 to 6 parts by weight of a plasticizer is added to 100 parts by weight of polyvinyl chloride.
A soft or semi-hard material added with about 0 parts by weight is preferable. The thickness of both the backing sheet and the intermediate sheet may be in the range of 50 to 1000 μm.

The base cloth is for increasing the dimensional stability of the screen, and when it is used as a roll-up type screen, it is required to have a function to prevent the drawn screen from sagging. In addition, when the screen that has been wound up and stored is rewound and used for projection again, the image is distorted if the curl remains, so that the base cloth is required to have sufficient elasticity and rigidity. A glass fiber woven or non-woven fabric satisfies these requirements.

The plastic used for the light diffusing layer may be of the same type as the backing sheet or the intermediate sheet described above.

The examples of the bright pigment are as follows. (A) What is called a pearl pigment, specifically, crushed powder of the inside of shells and pearls, mica, mica fine particles baked with TiO ₂ or iron oxide, (b) metal powder, specifically Include copper, aluminum, brass, bronze, gold, silver, etc., preferably 1 to 120 μm
Of the above, (c) Fragments of vapor-deposited plastic film, for example, polyethylene terephthalate film vapor-deposited with the above metal, usually aluminum. As these bright pigments, those having a scaly shape are used. The amount of the scaly bright pigment added to the plastic is preferably 0.5 to 10% by weight, and more preferably about 2% by weight.

The thickness of the light diffusion layer is 40 to 8 in consideration of keeping the image bright by reducing the attenuation of reflected light.
A range of 00 μm is suitable.

The surface of the light diffusion layer may be embossed. The emboss pattern may be a pattern in which corrugations cross 90 ° as is commonly used in conventional reflection type screens. When light is diffused with a large half value angle in the horizontal direction, the axis has a vertical half direction. Embossing that provides a cylindrical lenticular lens group is preferred. From the viewpoint of preventing moire fringes from appearing on the screen, it is appropriate to use a matte pattern, a grainy pattern, a hairline, or any pattern with no periodicity in the concave-convex pattern. Image is preferable. 90 ° corrugation, which is commonly used for conventional reflective projection screens
When using a concavo-convex pattern having a periodicity such as a crossing pattern or a pattern in which lattice-shaped, quadrangular or hexagonal cellular depressions are continuous, the direction of the concavo-convex pattern is relative to the direction of the projection pixel Therefore, it may have an inclination of 15 to 75 °.

The above screen can be manufactured by stacking a base material and a plastic sheet to be a light diffusing layer, and heating and pressurizing them to integrate them. When the above-mentioned laminated body is used as the base material, the step of first forming the base material and laminating the light diffusion layer on the base material as described above may be followed, or a laminated body of a backing sheet, an intermediate sheet and a light diffusion layer. It is also possible to use a method in which the and are integrated with each other by heating and pressurizing the glass fiber base cloth. The integration can be performed by either a heat fusion method or a dry laminating method. The light diffusion layer may be laminated on the base material or the intermediate sheet by coating the base material or the intermediate sheet with a plastic ink, paint or sol to be the light diffusion layer.

When embossing is provided on the surface of the light diffusing layer, it may be embossed at the same time as the integration, or the plastic sticky sheet serving as the light diffusing layer may be embossed beforehand.
You may choose the order which integrates this with a base material. In the latter case, the unevenness is formed with a cured resin so that the unevenness on the surface of the light diffusion layer is not crushed by the heat and pressure at the time of integration. A method called a drum printing method using an ionizing radiation curable resin (Japanese Patent Laid-Open No. 2-131175) is suitable for forming irregularities on the sheet surface with the cured resin.

On the surface of the reflection type projection screen of the present invention,
This is recommended because if you print the outer frame using dark ink by an appropriate method such as silk screen printing, the edges of the image will be trimmed properly and the screen will become clearer. It is a mode.

In order to provide a realistic feeling when using a projection screen, it is advisable to place a speaker behind the screen and provide a large number of small holes at that position. The size of the small holes provided in the screen has a diameter of 0.5 to 2.
A range of 0 mm is appropriate, and if the aperture ratio is too large, the holes will be conspicuous and the back side of the screen will be visible, and if it is too small, it will be difficult for sound to pass, so 15 to 65%,
It is particularly preferable to set it in the range of 30 to 50%. Here, the "aperture ratio" is the ratio of the total area of the small holes to the area of the portion through which the sound of the screen passes. It is preferable that the shape of the small holes is one having no sharp corner such as a circle or an ellipse because it is difficult to tear when the screen is pulled. The small holes may be provided on the entire surface of the screen,
If the position of the speaker behind it is fixed, such as with a fixed screen, it should be provided only at the part facing the speaker. The screen is perforated by means of punching with a blade die, perforation with a drill, melting with a CO ₂ laser, or the like.

[0020]

While the projected light is incident on the projection screen from almost the normal direction, the stray light generally coming from outside the window or from the electric lamp in the room is incident from the direction having a certain inclination with respect to the normal line. On the other hand, the scale-like bright pigment is present in a state in which the layer surface is oriented in a direction substantially parallel to the screen surface during the production of the light diffusion layer.

Now, let L _{P be} the amount of projection light incident on the projection screen, L _{S be} the amount of stray light, R _{P be} the amount of projection light that emerges after reflection, and R _S be the amount of stray light.

Assuming that the area ratio of the bright pigment in the total area viewed from the direction of the projection light of the projection screen (represented by the vertical line) is K, as shown in FIG. 2, the quantity of incident projection light L _P Is the portion K · L _P that is incident on the pigment surface and the portion (1-K) · L _P that reaches the substrate surface through the pigment gap.
Divided into

Similarly, the area ratio of the bright pigment in the total area of the projection screen viewed from the direction of stray light (which comes from various directions inclined with respect to the vertical line, but is represented by the inclination θ) is K ′. Then, as shown in FIG. 3, the amount of incident stray light L _S is divided into a portion K ′ · L _S incident on the pigment surface and a portion (1-K ′) · L _S reaching the substrate surface. ..

In a conventional projection screen using a white base material, if the surface reflectance of both the bright pigment and the white base material is 100%, the reflected projection light amount R _P ,
The amount of stray light R _S is R _P = 1 × K · L _P + 1 × (1-K) · L _P = L _P R _S = 1 × K ′ · L _S + 1 × (1-K ′) · L becomes _S = L _S, the light amount of the light amount and the stray light of the SN ratio or projected light without changing the incident light even at _{R P / R S = L P} / L S reflected light, improvement is not observed.

On the other hand, since the projection screen of the present invention uses the black base material, the reflectance on its surface is 0.
%, R _P = 1 × K · L _P + 0 × (1-K) · L _P = K · L _P R _S = 1 × K ′ · L _S + 0 × (1-K ′) · L _S = K ′ · L _S , and the SN ratio is expressed as R _P / R _S = K · L _P / K ′ · L _S.

As is clear from the comparison between FIG. 2 and FIG. 3, K ′ = K · cos θ and cos θ <1 under the condition of θ> 0, so K ′ <K, that is, K / K ′>. It is 1.

If the above equation is transformed into (R _P / R _S ) / (L _P / L _S ) = K / K ', then R _P / R _S > L _P / L _S The SN ratio of the light is improved than that of the incident light. In this way, a high-contrast image is projected.

From the above, it can be seen that the projection screen of the present invention is less susceptible to stray light than the conventional projection screen, and the image is clear even when used in a bright place.

[0029]

Example A black polyvinyl chloride sheet (DOP: 60 phr) having a thickness of 200 μm in which a carbon black pigment is kneaded is prepared as a backing sheet which becomes a base material after lamination.
In addition, a glass fiber woven base fabric and a 130 μm thick black vinyl chloride calendar sheet (DOP: 60 phr) in which a carbon black pigment was kneaded were prepared as an intermediate sheet.

A base cloth and an intermediate sheet were laminated in this order on the above-mentioned backing sheet, and further about 2% by weight of a pearl pigment (scale-like titanium coated mica having an average particle size of 17 μm) as a light diffusion layer was kneaded and extruded. Molded, thickness 120
μm translucent polyvinyl chloride sheet (DOP: 60ph
r) and a matte embossing plate with a grain pattern were sequentially stacked, and they were laminated and integrated by hot pressing and embossed.
After allowing to cool, it was peeled off from the embossing plate to obtain the reflection type projection screen of the present invention.

[0031]

According to the projection screen of the present invention, a high image contrast can be obtained and a clear image can be projected even in a bright place. It is easier to manufacture than the type using black stripes, and the yield of good products is high.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining an example of a projection screen of the present invention.

FIG. 2 is a conceptual diagram for explaining the trajectory of projection light on the projection screen of the present invention.

FIG. 3 is a view similar to FIG. 2 for explaining the trajectory of stray light on the projection screen of the present invention.

[Explanation of symbols]

 1 Light Diffusion Layer 2 Bright Pigment 3 Dark Base Material 4 Backing Sheet 5 Base Fabric 6 Intermediate Sheet 7 White Base Material

Claims (3)

[Claims] 1. A reflection-type projection screen comprising a light-diffusing layer made of a semitransparent plastic sheet in which a scaly bright pigment is kneaded, on a substrate having dark-colored surfaces. 2. The reflection type projection screen according to claim 1, wherein a backing sheet which is a dark plastic sheet and a glass fiber base cloth and an intermediate sheet which is a dark plastic sheet are laminated as a substrate. 3. The reflection type projection screen according to claim 1, wherein the surface of the light diffusion layer is embossed.