JP2000187277A - Projection screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection screen, having a wide field range and capable of obtaining a high-quality image superior in resolution and contrast. SOLUTION: This projection screen is constituted by arranging many plastic light transmissivie strands, having light transmissivity in parallel and has a light absorption part provided along in the longitudinal direction of the light transmissive strands in contact with both side parts of the adjacent light transmissive strands on an observation side. Also a distance (T) between a protrusive part on the observation surface side and that on the non-observed surface side of the light transmissive strand and a splicing length (L) of the adjacent light transmissive strands are made to satisfy the, inequality 0.15<=L/T<=0.6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive projection screen used as a screen of a projection television, a microfilm reader, or the like, and more particularly, to a high-quality image having a wide field of view, excellent resolution and contrast. The present invention relates to a projection screen that can be provided.

[0002]

2. Description of the Related Art Projection screens include television images,
A Fresnel lens sheet that is widely used to project a microfilm image or the like and realize the intended display, and is generally arranged on the light source side and focuses incident light in the direction of the observer, and is arranged on the observation side And a lenticular lens sheet for diffusing light rays in the horizontal direction. Among them, the lenticular lens sheet is a lens in which a predetermined lens is attached to the entrance surface or the exit surface or both the entrance surface and the exit surface so that the lenticular lens sheet is bright when viewed from the observation side and the viewing angle is enlarged. A sheet is used. In general, a double-sided lenticular lens sheet having a lenticular lens formed on an entrance surface and an exit surface is used. In recent years, high definition televisions have been actively pursued, such as clear vision and high vision, and the demand for high resolution and high contrast has been further increased in projection screens. In particular, double-sided lenticular lens sheets have been required. Fine pitch and a high BS ratio (the ratio of the light absorbing portion to the exit surface) have been required.

On the other hand, in a projection screen using a double-sided lenticular lens sheet, the deviation of the optical axis of the double-sided lens has a bad influence on the screen characteristics. It is necessary to do exactly.
However, in the extrusion method, the casting method by cell casting, the hot pressing method, and the like, which are performed as a method of manufacturing a double-sided lenticular lens sheet, a metal mold or the like is directly or indirectly formed on a resin plate. Since it is a method of transferring, it is difficult to accurately perform all of the dimensional accuracy of the master, the temperature control of the mold during molding, and the positioning of the double-sided master.
It has been difficult to sufficiently improve the positioning accuracy of the lenticular lenses on both sides. In particular, with the conventional manufacturing method as described above, it is not easy to make a large pitch of a large double-sided lenticular lens sheet exceeding 1 meter square by reducing the displacement of the lens position on both the front and back surfaces, and it is not easy to make the fine pitch. Couldn't respond enough.

Accordingly, the applicant of the present invention has disclosed in
No. 33 or JP-A-3-200948, adjacent orifices for forming adjacent light-transmitting strands are closely arranged at small intervals, and the diameter of the orifice immediately after the molten resin is spun from the orifice. Adjacent translucent strands are fused together by a phenomenon that expands in the direction (the Belas effect), so that a large number of translucent strands are fused and joined in parallel and integrated into a sheet. We have proposed a double-sided lenticular lens sheet. Further, in Japanese Patent Application Laid-Open No. Hei 4-267234, in order to improve the contrast of the projection screen and to prevent the generation of flare light, a projection screen joined through a portion including a light-absorbing partition between light-transmitting strands is disclosed. is suggesting.

[0005]

However, in a projection screen using such a double-sided lenticular lens sheet, the contrast decreases when the horizontal viewing range is widened, and the BS ratio is increased to increase the contrast. Then, there is a problem that the visual field range becomes narrow, and it has been difficult to obtain a projection screen that can satisfy both the characteristics of the horizontal visual field range and the contrast. Therefore, in the present invention,
It is an object of the present invention to provide a projection screen having an excellent resolution that satisfies both a wide viewing range and high contrast.

[0006]

In view of such circumstances, the present inventors have determined that the shape of the light-transmitting strands and light absorbing portions of the double-sided lenticular lens sheet constituting the projection screen is within a specific range. As a result, it has been found that the characteristics of both a wide viewing range and a high contrast in a projection screen can be satisfied at the same time, and the present invention has been achieved.

That is, the projection screen according to the present invention comprises a plurality of plastic translucent strands having translucency arranged in parallel, and being in contact with both sides of the adjacent translucent strands. A projection screen having a light absorbing portion provided on the observation side provided along the longitudinal direction of the transparent strand, wherein a distance (T) between a convex portion on the observation surface side and a convex portion on the non-observation surface side of the translucent strand; The joint length (L) between adjacent light-transmitting strands satisfies the following expression (1).

[0008]

## EQU3 ## 0.15 ≦ L / T ≦ 0.6 (1)

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The projection screen of the present invention is shown in FIG.
As shown in (1), a large number of light-transmitting strands 1 are arranged in parallel, adjacent light-transmitting strands 1 are joined at their side portions to be integrated into a sheet, and between the light-transmitting strands 1. A double-sided lenticular lens sheet in which the light absorbing portion 2 is formed along the longitudinal direction of the light-transmitting strand 1, wherein the light-transmitting strand 1 has a convex portion on the observation surface side and a convex portion on the non-observation surface side. It is necessary that the inter-distance (T) and the joining length (L) of the adjacent translucent strands 1 satisfy the above expression (1). This is because the light beam incident on the double-sided lenticular lens sheet once converges at the exit surface or near the exit surface and then spreads at a wide angle to expand the horizontal field of view. Bond length of adjacent translucent strands 1 (Joint length of adjacent translucent strands 1 (L) with respect to the distance (T) between the convex portions on the observation surface side and the non-observation surface side of translucent strands 1 (T) )) And the BS rate.

That is, when the joining length ratio (L / T) of the adjacent translucent strands 1 is less than 0.15, the horizontal viewing range is widened, but the contrast of the projection screen tends to decrease. At the same time, the mechanical strength of the double-sided lenticular lens sheet itself tends to be impaired, and the sheet tends to be broken during handling or use. Further, if the joining length ratio (L / T) exceeds 0.6, the horizontal viewing range tends to be unable to be sufficiently widened. The joint length (L / T) is 0.18 to 0.1.
55 is preferable, and more preferably 0.2 to 0.5.
5 range.

In the projection screen of the present invention, as a material constituting the translucent strand 1, for example, thermoplastic resin such as polymethyl methacrylate, polycarbonate, polyvinyl chloride, polystyrene, etc., which has good transparency and excellent workability. Alternatively, a cross-linkable resin such as a copolymer resin thereof, a cross-linkable silicone resin, a cross-linkable acrylic resin, or an ion cross-linkable resin is used. Among them, polymethyl methacrylate is preferable from the viewpoint of transparency and processability, and polycarbonate resin is preferable from the viewpoint of mechanical properties such as impact resistance, heat resistance, water resistance and dimensional stability. Further, additives such as a light stabilizer, a heat resistance deterioration inhibitor, a flame retardant, and a tinting agent can be mixed into these materials.

The cross-sectional shape of the translucent strand 1 of the projection screen of the present invention may be any of various shapes such as a substantially oval shape, a circular shape, or a ball shape depending on the shape of the opening of the orifice of the nozzle used and the spinning conditions. You can choose. The size of the translucent strand 1 varies depending on the use and purpose of the screen, but is generally about 0.1 to 1.5 mm.
The present invention can sufficiently cope with a fine pitch of the screen, and can provide a high-definition projection screen having a high resolution.

In the present invention, the width (P) of the light-transmitting strand 1 and the width (B) of the light-absorbing portion 2 are defined by the following (2).
By setting the range to satisfy the expression, the balance between the visual field range and the contrast can be further optimized, which is preferable.

[0014]

0.2 ≦ B / P ≦ 0.7 (2) That is, the width (P) of the translucent strand 1 and the light absorbing portion 2
By setting the ratio (B / P) to the width (B) to 0.3 or more, a sufficiently high contrast can be obtained, and 0.7
This is because a sufficient wide field of view can be obtained by the following. This ratio (B / L) is more preferably in the range of 0.25 to 0.65, and particularly preferably 0.1 to 0.6.
It is in the range of 3 to 0.5.

In the present invention, as a material constituting the light absorbing portion 2, for example, an acrylic resin, a polycarbonate resin, a thermoplastic resin such as polyvinyl chloride, polystyrene or the like is used as a base material, and a light-shielding agent is used. What is contained in the range of about 1 to 5% by weight is used. As a light blocking agent,
Pigment-based, dye-based, carbon black-based, or a mixture thereof can be used. Further, additives such as a flame retardant and a matting agent may be added to these materials as needed. Acrylic resin is preferable as the base resin of the light absorbing portion 2, and as the acrylic resin, a homopolymer of methyl acrylate or methyl methacrylate,
Copolymer of methyl methacrylate and styrene, copolymer of methyl acrylate and methyl methacrylate, methyl acrylate or methyl methacrylate and ethyl (meth) acrylate, butyl (meth) acrylate,
Copolymers with (meth) acrylonitrile and the like can be mentioned. Among them, a homopolymer of methyl methacrylate and a copolymer of methyl methacrylate and styrene are particularly preferable.

Such a projection screen of the present invention is manufactured in principle by a melt extrusion technique.
The manufacturing example will be described in detail with reference to FIG. In FIG. 2, reference numeral 3 denotes an extruder, and 4 denotes a nozzle holder provided with a nozzle, which discharges a molten thermoplastic resin such as a polycarbonate resin or an acrylic resin from an orifice.
The discharge direction may be either upward or downward, but upward discharge is preferable in terms of uniformity of the translucent strand and setting of the pitch. As the nozzle 11, for example, a nozzle in which orifices 12 and 13 shown in FIGS. 3 and 4 (a partially enlarged view of FIG. 3) are arranged in a substantially horseshoe shape is used. The orifice 12 discharges a thermoplastic resin for forming a light-transmitting strand, and the orifice 13 discharges a thermoplastic resin containing a light absorbing agent for a light absorbing portion.

The discharged translucent strands 1 are fused and integrated with each other by a bales effect in which the molten thermoplastic resin expands in the radial direction immediately after being spun from the orifice 12. Thus, an annular sheet 5 in which the light absorbing portions 2 are formed between the translucent strands 1 on one surface is obtained. This annular sheet 5 is pulled up along the inner wall of the annular guide 6, and the annular sheet is spread into a planar sheet by the iron-shaped guide 7 and the rod-shaped straight guide 8, and at the same time, the traveling direction of the sheet is changed by the rod-shaped straight guide. Pick up by nip roller 9 and reel 10
It is wound up. If necessary, the sheet may be slightly stretched by heating.

In the present invention, it is desirable that the horizontal visual field range of the projection screen is large enough to allow an image to be observed even from a position at 50 degrees from the front. It is desirable that a sufficiently high gain be obtained in the angle range from -50 degrees to +50 degrees. The mechanical strength of a double-sided lenticular lens sheet
The sheet must have a mechanical strength that does not crack when handling or using the sheet, and it is desirable that the absorbed energy value using an Izod impact tester be 0.3 kgf · cm or more. In addition, the evaluation of the characteristics of the projection screen was performed using a goniometer (automatic variable-angle photometer) (GP-IR type, manufactured by Murakami Color Research Laboratory Co., Ltd.). Regarding the mechanical strength of the double-sided lenticular lens sheet, using an Izod impact tester, a hammer lifting angle of 135 degrees, a weighing of 30 kgf · cm, several test pieces of a sheet sample having a sheet width of 20 mm and a sheet length of 64 mm were used. Evaluation was made on the absorbed energy per sheet when the sheets were superposed and hit in the horizontal direction with respect to the longitudinal direction of the lenticular lens.

[0019]

The present invention will be specifically described below with reference to examples. Example 1 A projection screen was manufactured by using the nozzle 11 shown in FIG. 3 and the apparatus shown in FIG. In the nozzle 11, 1,000 orifices 12 each having a hole diameter of 1 mm for a light-transmitting strand are annularly arranged at a pitch of 1.25 mm, and orifices 13 each having a hole diameter of 0.5 mm for a light absorbing portion are arranged between the orifices 12 in the same number. I have.

In the orifice 12, a copolymer resin of methyl methacrylate and styrene (TX-40 manufactured by Denki Kagaku Kogyo Kogyo)
The melt of 0) was supplied at 0.2 g / min per orifice, and the orifice 13 was prepared by mixing 2% by weight of carbon black with a copolymer resin of methyl methacrylate and styrene (TX-200 manufactured by Denki Kagaku Kogyo). The melt was fed at 0.07 g / min per orifice and the nozzle temperature was 24
Extruded upward at 5 ° C. After the extrusion, the annular sheet 5 formed by fusing the adjacent light-transmitting strands is pulled up along the inner wall of the annular guide 6 and developed into a flat sheet by the iron-shaped guide 7 and the rod-shaped straight guide 8. And wound up on a reel 10. The sheet was cooled by passing warm water of 50 ° C. into each guide.

In the obtained sheet, 1,000 translucent strands are completely fused and integrated at a pitch of 0.81 mm, are arranged uniformly in a plane, and a light absorbing portion is formed between the translucent strands. The translucent strand has a junction length ratio (L / T) of 0.47 and a BS ratio (B / P) of 0.58.
Was a double-sided lenticular lens sheet. As a result of measuring the screen characteristics of this projection screen, FIG.
As shown in Fig. 7, the image has good viewing angle characteristics, and an image can be observed from a wide angle position. In addition, it has a high contrast and the absorbed energy is 0.56 kgf · cm.
And the mechanical strength was also strong.

Example 2 A melt of a methyl methacrylate resin (VH manufactured by Mitsubishi Rayon Co., Ltd.) was supplied to the orifice 12 at a rate of 0.2 g / min per orifice in the same manner as described in Example 1, and the orifice 13 was supplied with methyl methacrylate. A mixed melt obtained by adding 2% by weight of carbon black to a resin (MF manufactured by Mitsubishi Rayon) was supplied at a rate of 0.05 g / min per orifice, and was extruded upward at a nozzle temperature of 240 ° C.

In the obtained sheet, 1,000 light-transmitting strands are completely fused and integrated, and are uniformly arranged in a plane, and a light-absorbing portion is formed between the light-transmitting strands. Is (L / T) 0.22 and the BS rate is (B /
P) A 0.43 double-sided lenticular lens sheet. As a result of measuring the screen characteristics of the projection screen, as shown in FIG. 6, the projection screen had good viewing angle characteristics, and an image could be observed from a wide angle position. In addition, it has high contrast and absorption energy of 0.34k
The mechanical strength was as strong as gf · cm.

Comparative Example 1 A melt of a methyl methacrylate resin (VH manufactured by Mitsubishi Rayon Co., Ltd.) was supplied to the orifice 12 at a rate of 0.2 g / min per orifice, and the orifice 13 was supplied with methyl methacrylate in the same manner as in Example 1. A mixed melt obtained by adding 1% by weight of carbon black to a resin (MF manufactured by Mitsubishi Rayon) was supplied at a rate of 0.05 g / min per orifice, and was extruded upward at a nozzle temperature of 240 ° C.

In the obtained sheet, 1000 light-transmitting strands are completely fused and integrated to be uniformly arranged in a plane, and a light absorbing portion is formed between the light-transmitting strands. Is (L / T) 0.59 and the BS rate is (B /
P) was 0.37 on both sides of the lenticular lens sheet. This projection screen has a high contrast and an absorption energy of 0.61 kgf · cm, which is also sufficient mechanical strength. However, as a result of the measurement of the screen characteristics, as shown in FIG. The light transmission gain was sharply reduced at around 45 degrees, and was not in a sufficient visual field range.

Comparative Example 2 A melt of a copolymer resin of methyl methacrylate and styrene (TX-400 manufactured by Denki Kagaku Kogyo Co., Ltd.) was applied to the orifice 12 in the same manner as described in Example 1 at a rate of 0.2 g / min per orifice. The orifice 13 was supplied with a mixed melt obtained by adding 1% by weight of carbon black to a methyl methacrylate resin (MF manufactured by Mitsubishi Rayon Co., Ltd.) at a rate of 0.07 g / min per orifice, and was extruded upward at a nozzle temperature of 245 ° C.

In the obtained sheet, 1000 light-transmitting strands are completely fused and integrated to be uniformly arranged in a plane, and a light absorbing portion is formed between the light-transmitting strands. (L / T) is 0.14 and BS ratio (B /
P) was a double-sided lenticular lens sheet of 0.68. As a result of measuring the screen characteristics, this projection screen had good viewing angle characteristics as shown in FIG. 8 and an image could be observed from a wide angle position, but the absorption energy was 0.23 kgf · cm. And low mechanical strength.

[0028]

According to the projection screen of the present invention, the distance (T) between the convex portion on the observation surface side and the convex portion on the non-observation surface side of the translucent strand and the joining length (L) of the adjacent translucent strands )
By specifying the ratio (L / T), it is possible to provide a projection screen capable of obtaining a high-quality image with a wide field of view and excellent resolution and contrast.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of a double-sided lenticular lens sheet of the present invention.

FIG. 2 is a schematic view of an apparatus used for manufacturing the projection screen of the present invention.

FIG. 3 is a schematic view of a nozzle used for manufacturing the projection screen of the present invention.

FIG. 4 is a schematic enlarged view showing a part of a nozzle used for manufacturing the projection screen of the present invention.

FIG. 5 is a graph showing measurement results of screen characteristics of Example 1.

FIG. 6 is a graph showing measurement results of screen characteristics in Example 2.

FIG. 7 is a graph showing measurement results of screen characteristics of Comparative Example 1.

FIG. 8 is a graph showing measurement results of screen characteristics of Comparative Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Translucent strand 2 Light absorption part 3 Extruder 4 Nozzle holder 5 Translucent strand annular sheet 6 Annular guide 7 Iron-shaped guide 8 Rod-shaped straight guide 9 Nip roller 10 Reel 11 Nozzle 12 Translucent strand orifice 13 Light Orifice for absorption part

Claims (2)

[Claims] 1. A plurality of plastic translucent strands having translucency are arranged in parallel, and are in contact with both sides of adjacent translucent strands along the longitudinal direction of the translucent strands. A projection screen having a light absorbing portion provided on the observation side provided on the observation side, wherein the distance (T) between the projection on the observation surface side and the projection on the non-observation surface side of the translucent strand and the distance between the adjacent translucent strands A projection screen, wherein a joining length (L) satisfies the following expression (1). (1) 0.15 ≦ L / T ≦ 0.6 (1) 2. The projection screen according to claim 1, wherein a width (P) of the translucent strand and a width (B) of the light absorbing portion satisfy the following expression (2). ## EQU2 ## 0.2 ≦ B / P ≦ 0.7 (2)