JPH10246916A - Transmission type screen and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transmission type screen that is prevented from generation of scintillation even when a light-diffusing material is used, and capable of obtaining image of high luminance, high resolution and high picture quality, by incorporating a specified amt. of spherical light-diffusing material or a crystalline macromolecular polymer into a transparent resin. SOLUTION: This transmission type screen B contains 0.01 to 30wt.% spherical light-diffusing material A comprising a crystalline macromolecular polymer in a transparent resin. It is preferable that the transparent resin of this transmission screen B is a methylmethacrylate resin and/or that the average particle size of the spherical light-diffusing material A is 1 to 30μm. The spherical light-diffusing material A consists of spherical particles of a marcomolecular polymer having a noncrystalline part and a crystalline part in the molecular chain. The crystalline macromolecular polymer can diffuse and mix light from each pixel, and therefore, scintillation of an image can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission screen used as a screen of a projection television, a microfilm reader, or the like.

[0002]

2. Description of the Related Art Conventionally, a rear projection type projection television has been required to be able to observe a projected image brightly in a wide range on an observation side. A transmission type screen having an anisotropy in a visual field range that diffuses into a narrower range than that is used. As such a transmissive screen, a lens sheet such as a lenticular lens extending vertically on one or both sides of the sheet is continuously provided, and a lens sheet containing a light diffusing material in a diffusion sheet is used. Diffuses light more horizontally than the lens
Generally, light is diffused in a vertical direction by a light diffusing material.

The light diffusing material has a high total light transmittance as a transmissive screen and is excellent in light use efficiency, and has a high diffusion light transmittance ratio (cloudiness value) in the total light transmittance. Excellent diffusion, high color temperature, no see-through of light sources such as CRTs and liquid crystal projectors called “see-through”, and no visible bright bands such as hot bands are observed. Performance is required. Examples of such light diffusing materials include silica muscovite described in JP-A-60-46503, inorganic light diffusing materials such as alumina, calcium carbonate and glass beads, and JP-A-1-23625.
For example, an acrylic resin, a styrene resin, a copolymer thereof, and an amorphous organic light diffusing material such as a silicone resin described in JP-A-1-172801 are used. As described above, by appropriately selecting the refractive index difference between the base resin forming the light diffusion layer and the light diffusion material, the particle diameter (distribution), and the shape of the particles, the performance required for the transmission screen is satisfied. It is known that it is possible to do this.

On the other hand, in recent years, CRTs have been
Instead, liquid crystal projectors using liquid crystal panels have been developed. Since this liquid crystal projector forms an image by passing or blocking light for each pixel, the light from the light source is usually made into parallel light to enter the liquid crystal panel. Therefore, the light of each pixel that has passed through the liquid crystal panel is not diffused like a CRT that emits light for each pixel, and is light with more uniform directivity. A commonly used liquid crystal panel is C
Since it is smaller than RT, the direction of light for each pixel is more uniform on a liquid crystal panel than on a CRT even on a screen.
In the light diffusing material used in such a liquid crystal projector, as described above, in order to improve the light diffusing property of the light diffusing material, excellent performance is exhibited by using a spherical light diffusing material. A transmission screen using a spherical light diffusing material has a disadvantage that scintillation occurs.

[0005]

When a bright light source having a uniform orientation is used as a projection source, such as a liquid crystal projector, a transmission type using a spherical light diffusing material as described above, which has been conventionally used, is used. On the screen, when you look at the image, the change in brightness due to the light diffusion material is clearly visible,
There has been a problem that a phenomenon called scintillation, in which the entire screen is glaring, occurs. In particular, when a still image such as a computer is projected, this scintillation is strongly felt, and there is a problem that the image becomes very difficult to view. However, in order to widen the vertical viewing range, it is necessary to use a certain amount of light diffusing material, and thus improve the scintillation of such an image while satisfying the performance required of the light diffusing material. At present, the light diffusing material has never been mentioned before. In order to solve such a problem of the scintillation, Japanese Patent Application Laid-Open No. 7-168282 proposes that the light diffusion layer is configured to be at least three times the focal length of the incident side lens. However, with this method,
Although the scintillation is solved, the image is blurred due to the distance between the lenticular lens and the light diffusion layer, and the resolution is significantly reduced.

[0006] Light diffusing materials that improve the scintillation of such images without reducing the resolution of the images and satisfying the performance required of the light diffusing materials have been mentioned so far. There is no current situation. Therefore, an object of the present invention is to provide a high luminance, no scintillation even when using a light diffusing material.
An object of the present invention is to provide a transmission screen capable of obtaining a high-resolution and high-quality image and a method of manufacturing the same.

[0007]

SUMMARY OF THE INVENTION The gist of the present invention is that a transparent type resin comprises a spherical light diffusing material comprising a crystalline high molecular polymer in an amount of 0.01 to 30% by weight. On the screen. Further, the transmission screen of the present invention can be further characterized in that the transparent resin is a methyl methacrylate resin and / or the spherical light diffusing material has an average particle diameter of 1 to 30 μm.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The spherical light diffusing material composed of a crystalline high molecular polymer contained in the transmission screen of the present invention is a spherical particle composed of a high molecular polymer having an amorphous part and a crystalline part in its molecular chain.

In such a crystalline polymer, there are portions having different refractive indexes inside the particles, and light diffusion elements other than the microlens action determined by the particle shape exist inside the particles. Therefore, even in the case of using a projection source such as a liquid crystal projector that has strong directivity and a lot of light with uniform direction, it is possible to diffuse and mix light for each pixel more than conventional light diffusion materials. Becomes
As a result, scintillation of the obtained image can be eliminated. The degree of crystallinity of the crystalline high molecular polymer used in the present invention is not particularly limited. However, when it is desired to diffuse light more, it is preferable that the degree of crystallinity be high. As the melting point increases, the melting point can be increased. Therefore, the heat resistance stability of the resulting transmission screen tends to be improved.

[0010] Such a crystalline polymer is not particularly limited, but specifically, for example,
Polyethylene, polypropylene, polyamide, polyacetal, polyvinylidene chloride, polyvinylidene fluoride,
Examples include polyethylene terephthalate and nylon 6. Among these, copolymer resins such as high-density polyethylene, low-density polyethylene, and acrylic / ethylene-based resins are preferable because the resulting screen has good vertical directivity, beads can be easily produced, and the cost is low. Particularly preferred are polyethylene resins such as The shape of the light diffusing material used in the present invention is a spherical shape including not only a true sphere but also a flat sphere from the viewpoint of securing the total light transmittance. In the present invention, the light diffusing material is a flat spherical light diffusing material. No scintillation occurs.

As described above, the light diffusing material used in the present invention is a spherical light diffusing material made of a crystalline polymer, so that the light diffusing material has better light diffusing performance than the conventional polymer light diffusing material and has a scintillation property. Which has an excellent performance that no odor occurs. Further, since the light diffusing material is spherical, even if a liquid crystal projector is used as a light source, the polarization of the projection light is not destroyed, and the present invention can be applied to a diffusion plate used for stereoscopic images using polarization.

The average particle diameter of the spherical light diffusing material used in the present invention may be appropriately selected according to the required performance of the transmission screen, but is in the range of 1 to 30 μm at which the obtained screen has a good total light transmittance. Is preferable, and the range of 3 to 20 μm is particularly preferable. When the average particle size is smaller than 1 μm, an image obtained by reducing the light transmittance of the short wavelength side in the visible light region, particularly, the blue component tends to be a yellowish image. If the diffusion layer is larger than this, the amount of addition required to obtain the same screen gain increases, and if the diffusion layer is formed to be thin to improve the resolution, production becomes difficult.

The content of the spherical light diffusing material used in the present invention is contained in the transparent resin in the range of 0.01 to 30% by weight. Is appropriately selected within this range according to the thickness of the film. Particularly preferably 0.05 to 25% by weight
And more preferably in the range of 0.1 to 20% by weight. When the content of the spherical light diffusing material is more than 30% by weight, the screen gain of the transmissive screen tends to decrease significantly, and the light use efficiency of the projection light decreases. On the other hand, if it is less than 0.01% by weight, the effect of widening the vertical viewing range of the transmission screen by the light diffusing material becomes insufficient. In the present invention, in addition to using the spherical light diffusing material alone, it is also possible to use the spherical light diffusing material together with another diffusing material as needed.

The transmissive screen of the present invention is not particularly limited. For example, as shown in FIG. 1, it is a plate-like type used as a light diffusing sheet, and as shown in FIGS. A type in which a lenticular lens shape is provided on at least one surface, or a lenticular lens shape type in which a light absorber is arranged between a plurality of adjacent translucent strands and integrated into a sheet as shown in FIG. The present invention can be applied to various types of transmission screens.

The transparent resin constituting the transmission type screen of the present invention is not particularly limited, and a commonly used transparent resin such as an acrylic resin, a methacrylic resin, a polycarbonate resin or the like may be appropriately used according to various required performances. Can be selected and used. Among them, a methyl methacrylate resin is particularly preferable because it has high total light transmittance and good moldability.

The transmission type screen of the present invention has the following features.
It can be easily and stably manufactured by a known method such as a monomer casting method, an extrusion molding method, and an injection molding method.

The thickness of the transmission screen of the present invention may be appropriately selected depending on the size of the product to be applied.
Generally, a transmission screen having a thickness of 5 mm or less is often used. When a higher resolution is required, a transmission screen having a thickness of 3 mm or less may be used.

If necessary, an anti-reflection film may be formed on at least one surface of the transmission screen of the present invention to prevent reflection of external light on the observation surface, thereby preventing deterioration in image quality. is there.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. In the present example, the screen gain was obtained by illuminating the sample with a constant illuminance, measuring the luminance on the opposite surface with a color luminance meter BM-7 manufactured by Topcon Co., Ltd. The ratio and the half angle of the screen gain in the vertical field of view are denoted as αv. Further, the total light transmittance (Tt) and the haze (Haze) were measured by a haze meter (product number: HR-100) manufactured by Murakami Color Research Laboratory Co., Ltd. in accordance with JIS K6717. It is a measured value.

Example 1 In a partially polymerized methacrylic resin, a light diffusing material composed of a crystalline high molecular polymer was used.
3% by weight of high-density polyethylene resin particles (manufactured by Sumitomo Seika Co., Ltd., trade name: Flowbead HE3040, spherical particles having an average particle diameter of 9 μm) were added, and the plate thickness was 2 m by a cell casting method.
m of a methacrylic resin plate. In the obtained methacrylic resin plate, the light diffusing material was uniformly dispersed in the base material. The screen gain, total light transmittance, and haze value of this methacrylic resin plate were measured, and the results are shown in Table 1. Further, the obtained methacrylic resin plate was used as a transmission screen and 37
Inch LCD projection TV (Sharp Corporation)
(Trade name: Gaia), and observed from a position 3 m away from the projection television, and scintillation was visually evaluated. As a result, as shown in Table 1, glare did not occur, the total light transmittance was high, and the video had a uniform brightness over the entire screen, and a high-quality image without uneven brightness was obtained.

Example 2 Low-density polyethylene resin particles (trade name: Flowbeads LE108, manufactured by Sumitomo Seika Co., Ltd.)
0, spherical particles having an average particle diameter of 6 μm), and a methacrylic resin plate was formed in the same manner as in Example 1 except that 1.7% by weight was added. As a result of performing the same evaluation as in Example 1 on the obtained methacrylic resin plate, as shown in Table 1, no glare occurred, the total light transmittance was high, and the image had uniform brightness over the entire surface. High quality images without unevenness were obtained.

Example 3 1.6% by weight of the high-density polyethylene resin particles used in Example 1 were added, and a methacrylic resin sheet having a thickness of 1 mm was formed by a cell casting method. The screen gain of the obtained methacrylic resin plate was 20. This methacrylic resin plate is brought into contact with a lenticular lens mold, a lens shape having a lens pitch of 0.3 mm and a circular shape is provided on the light incident side of the diffusion sheet by hot press molding, and the light on the light emitting side is further printed. A black stripe was formed in the non-transmissive part, and a lens sheet was manufactured as shown in FIG. The screen gain of the obtained lens sheet was 5. The obtained lens sheet was evaluated in the same manner as in Example 1. As shown in Table 1, no glare occurred, the total light transmittance was high, the image had uniform brightness over the entire surface, and uneven brightness was observed. No high-quality images were obtained.

Comparative Example 1 Amorphous spherical polystyrene beads (trade name: SBX-8, manufactured by Sekisui Chemical Co., Ltd.)
Was added, and a methacrylic resin plate was formed in the same manner as in Example 1 except that 0.8% by weight was added. As a result of evaluating the obtained methacrylic resin plate by the same method as in Example 1,
As shown in Table 1, the screen gain was 5, and the image had uniform brightness over the entire surface, but scintillation occurred and the image was very hard to see.

Comparative Example 2 The amorphous spherical polystyrene beads used in Comparative Example 1 were added in an amount of 0.5% by weight, and a methacrylic resin plate having a thickness of 1 mm was formed by a cell casting method. The screen gain of the obtained methacrylic resin plate was 2
It was 0. Using this methacrylic resin plate, a lens sheet was produced as shown in FIG.
The screen gain of the obtained lens sheet was 5, and although the image had uniform brightness over the entire surface, scintillation occurred and the image was very hard to see.

[0025]

[Table 1]

[0026]

According to the present invention, even when a light source such as a liquid crystal projector having a high linearity of light is used as a projection source, a transmissive screen which can provide a high-quality image without noticeable scintillation can be easily obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a cross section of an embodiment of a transmission screen of the present invention.

FIG. 2 is a schematic view showing a cross section of one embodiment of a transmission screen of the present invention in which a lenticular lens is provided on one side.

FIG. 3 is a schematic view showing a cross section of one embodiment of a transmission screen of the present invention in which lenticular lenses are provided on both sides.

FIG. 4 is a schematic diagram showing a cross section of one embodiment of a transmission screen of the present invention in which a lenticular lens is provided on one side.

[Explanation of symbols]

 A: Spherical light diffusing material composed of a crystalline polymer B: Transmission screen C: Light absorber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuko Ikeda 3816 Noborito, Tama-ku, Kawasaki City, Kanagawa Prefecture Mitsubishi Rayon Co., Ltd. Tokyo Technology and Information Center

Claims (4)

[Claims] 1. A transmissive screen comprising a transparent resin containing 0.01 to 30% by weight of a spherical light diffusing material made of a crystalline polymer. 2. The transmission screen according to claim 1, wherein the transparent resin is a methyl methacrylate resin. 3. The spherical light diffusing material has an average particle diameter of 1 to 30 μm.
3. The transmission screen according to claim 1, wherein m is m. 4. A method for producing a transmission screen, comprising uniformly dispersing a spherical light diffusing material comprising a crystalline high molecular polymer in a transparent resin.