JP2000194075A - Screen for stereoscopic image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To observe an excellent stereoscopic image having no feeling of incompatibility by making extinction shown by a specified expression including parallel luminance and vertical luminance in a linear polarization state satisfy a specified condition. SOLUTION: On a screen constituted of a lenticular lens sheet, at least either surface of which a lenticular lens is formed on, the extinction shown by the expression is >=15 dB when the parallel luminance and the vertical luminance in the linear polarization state are defined as Lh and Lv, respectively. In order to obtain a stereoscopic image having no feeling of incompatibility, it is desirable that the extinction obtained in the case of arranging the screen so that the axis of polarization of a 1st polarizing film may be a 45-degree direction is >=10 dB, more desirably, >=15 dB. In order to obtain the screen for the stereoscopic image whose extinction is >=15 dB, it is important to make the double refractivity of the screen small. By producing the screen in such a producing method that molding distortion is not caused inside, the desired screen is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional image screen using a lenticular lens sheet, and more particularly, to a three-dimensional image screen capable of observing an excellent three-dimensional image without a sense of discomfort.

[0002]

2. Description of the Related Art A stereoscopic image system has been widely used in amusement parks, game centers, and the like because it can observe images having a three-dimensional effect and can provide a sense of realism and depth. As such a stereoscopic image system, there are a type that uses glasses with polarizing films and a type that directly views without using such polarizing glasses, and a type that does not use polarizing glasses has a position where a stereoscopic image can be observed. The type that uses polarized glasses has become mainstream because it is fixed. Also, as a system for observing a large-screen stereoscopic image in order to further enhance the sense of reality, a projection type is suitable, and a projection type using polarized glasses is widely used. Above all, demand for rear projection type stereoscopic projection televisions has been increasing in recent years because clear images can be viewed even in a bright environment.

Conventionally, as a screen used in a stereoscopic video system of the type using polarized glasses, a screen having the same configuration as a screen used in a normal projection television has been used.
As disclosed in JP-A-8-274159, a single-sided lenticular lens sheet in which a lenticular lens is formed on one surface and a light-shielding pattern is formed on the other surface as disclosed in JP-A-10-101481. A screen or the like is used in which a Fresnel lens sheet and two single-sided lenticular lens sheets are stacked in parallel so that lenticular lenses are arranged on a light incident surface and a light exit surface.

[0004]

However, such a conventional screen is manufactured as a lenticular lens sheet by extrusion molding of an acrylic resin or the like, or by hot press molding of an extrusion plate of an acrylic resin or the like. Since molding is performed at a temperature near the glass transition temperature of the base resin, considerable internal strain remains in the lenticular lens sheet, and the birefringence of the lenticular lens sheet increases due to the internal strain. Thus, the polarization of the screen was reduced.
For this reason, there is a problem that even if the image is observed using polarized glasses, the image cannot be seen three-dimensionally, or the image is difficult to see, and the eyes are very tired, and a three-dimensional image can be provided without a sense of discomfort. Was not. Therefore, in the present invention,
It is an object of the present invention to provide a three-dimensional image screen capable of observing an excellent three-dimensional image without a sense of discomfort.

[0005]

SUMMARY OF THE INVENTION In view of such circumstances, the present inventors have set the extinction degree in a linearly polarized state to a specific range in a three-dimensional image screen using a lenticular lens sheet. The inventors have found that it is possible to provide a stereoscopic image without a sense of incongruity, and have reached the present invention.

That is, the three-dimensional image screen of the present invention is a screen composed of a lenticular lens sheet having a lenticular lens formed on at least one surface thereof.
h, when the vertical luminance is Lv, the extinction degree represented by the following equation (1) is 15 dB or more.

[0007]

Extinction degree (dB) = 10 × log ₁₀ (Lh / Lv) (1)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The three-dimensional image screen of the present invention is capable of observing a three-dimensional image without a sense of incongruity by setting the extinction degree in the linearly polarized state represented by the above formula (1) to 15 dB or more. It is. In the present invention, the extinction degree is a value as a screen, and when a lenticular lens sheet and a Fresnel lens sheet are used in combination, the extinction degree means a combination of both.

When the extinction degree is 10 dB or more, a three-dimensional image can be observed as a three-dimensional image screen. However, in order to observe the three-dimensional image without discomfort, the extinction degree must be 15 dB or more. Is more preferable, and it is more preferably in the range of 20 dB or more.

In the present invention, the extinction degree of the screen is determined by setting a first polarizing film so that the polarization axis is perpendicular to the lens of the slide projector as a light source, and the distance between the light source and the screen is 3 m. And a luminance meter is installed on the opposite side of the light source so that the distance from the screen is 3.3 m. A second polarizing plate of the same type as the first polarizing film is provided on the luminance meter side of the screen. Luminance when a polarizing film is arranged such that the polarization axis of the second polarizing film is perpendicular (parallel luminance: Lh)
And the luminance (vertical luminance: Lv) when the polarization axis of the second polarizing film is rotated by 90 degrees is measured by a luminance meter.
This is calculated based on the above equation (1). In this case, the light source and the luminance meter are installed at the center of the screen.

In the stereoscopic image screen of the present invention, in order to obtain a stereoscopic image without a sense of incongruity, in the measurement of the extinction degree, the polarization axis of the first polarizing film is 45 degrees.
10 dB
It is preferably at least 15 dB, more preferably at least 15 dB.

In order to obtain a three-dimensional image screen having an extinction degree of 15 dB or more as in the present invention, it is important to reduce the birefringence of the screen. Thus, a desired screen can be obtained. In this case, after shape transfer and molding are performed at a temperature equal to or higher than the glass transition temperature of the base material, it is important to perform slow cooling so that internal distortion does not occur. Further, it can also be obtained by removing distortion generated inside by a distortion removing process or the like.

An example of a method for manufacturing a lenticular lens sheet having a small birefringence and a small internal distortion will be described below with reference to FIGS. The lenticular lens sheet of the present invention is manufactured in principle by a melt extrusion technique. In FIG. 1, 1 is an extruder, 2 is a nozzle holder provided with a nozzle, and 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 9, for example, one having orifices 10 and 11 arranged in a substantially horseshoe shape as shown in FIGS. 2 and 3 (a partially enlarged view of FIG. 2) is used. The orifice 10 discharges a thermoplastic resin for forming a light-transmitting strand, and the orifice 11 discharges a thermoplastic resin containing a light absorbing agent for a light absorbing portion. The discharge temperature of the nozzle 9 is 220
It is preferable to be in the range of -270 ° C.

The discharged translucent strands are fused and integrated with the adjacent translucent strands by a bales effect in which the melted thermoplastic resin expands in the radial direction immediately after being spun from the orifice 10, An annular sheet 3 in which a light absorbing portion is formed between the translucent strands on one surface.
Becomes The annular sheet 3 is pulled up along the inner wall of the annular guide 4, and the annular sheet is spread by the iron-shaped guide 5 and the bar-shaped straight guide 6 into a flat sheet.
At the same time, the traveling direction of the sheet is changed by a rod-shaped straight guide, the sheet is taken up by a nip roller 7, and is wound up on a reel 8. If necessary, the sheet may be slightly stretched by heating. During the period from discharge to winding, the temperature of the sheet is controlled so that the sheet is not rapidly cooled, and the sheet is gradually cooled to prevent internal distortion.

In the lenticular lens sheet manufactured as described above, as shown in FIG. 4, a number of light-transmitting strands 12 are arranged in parallel, and adjacent light-transmitting strands 12 are joined at their side portions. And a light absorbing portion 13 is formed between the light transmitting strands 12 so as to protrude from the surface of the light transmitting strand 12 along the longitudinal direction of the light transmitting strand 12. It becomes a lenticular lens sheet. As described above, by forming the light absorbing portions 13 so as to protrude from the surface (the lenticular lens surface) of the translucent strand 12, the contrast of an image can be significantly increased. As a material constituting the translucent strand 12, for example, a thermoplastic resin such as polymethyl methacrylate, polycarbonate, polyvinyl chloride, polystyrene or the like, which has good transparency and excellent workability, or a copolymer resin thereof, or a cross-linkable resin A cross-linkable resin such as a silicone resin, a cross-linkable acrylic resin, or an ion cross-linkable resin is used. Among them, polymethyl methacrylate is preferred from the viewpoint of transparency and processability,
From the viewpoint of mechanical properties such as impact resistance, heat resistance, water resistance and dimensional stability, polycarbonate resins are preferred.
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 light-transmitting strand 12 can be appropriately selected from various shapes such as a substantially oval shape, a circular shape, and a ball shape depending on the shape of the opening of the orifice of the nozzle used and the spinning conditions. Further, the size of the translucent strand 12 varies depending on the use and purpose of the screen, but is generally about 0.1 to 1.5 mm, which can sufficiently cope with a fine pitch of the screen, and has a high resolution. Can be provided.

The light-absorbing portion 13 is made of, for example, a thermoplastic resin such as an acrylic resin, a polycarbonate resin, polyvinyl chloride, or polystyrene as a base material, and a light-shielding agent of 0.1 to 5 weight%. % Is used. As the light-shielding agent, pigment-based, dye-based, carbon black-based ones, or a mixture thereof can be used. In addition to these materials flame retardant,
Additives such as matting agents may be added as necessary. Acrylic resin is preferable as the base resin of the light absorbing section 2, and as the acrylic resin, a homopolymer of methyl acrylate or methyl methacrylate, a copolymer of methyl methacrylate and styrene, and a copolymer of methyl acrylate and methyl methacrylate And a copolymer of methyl acrylate or methyl methacrylate with ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, and the like. Among them, a homopolymer of methyl methacrylate and a copolymer of methyl methacrylate and styrene are particularly preferable.

The lenticular lens sheet obtained as described above has a small birefringence and a small internal distortion. However, when used in combination with a Fresnel lens sheet or a front plate as a three-dimensional image screen. It is preferable to use a Fresnel lens sheet or front plate having a small birefringence and a small internal strain.
Examples of such a Fresnel lens sheet and the front plate include those manufactured by a casting method.

[0019]

The present invention will be specifically described below with reference to examples. Example 1 Using the nozzle 9 shown in FIG. 2, a lenticular lens sheet was manufactured using the apparatus shown in FIG. The nozzle 9 is provided with an orifice 10 having a hole diameter of 1 mm for a light-transmitting strand at 1.25.
1,000 orifices are arranged annularly at a pitch of mm and the same number of orifices 11 having a hole diameter of 0.5 mm for the light absorbing portion are arranged between the orifices 10.

In the orifice 10, 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 11 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 being extruded, the annular sheet 5 formed by fusing the adjacent translucent strands is pulled up along the inner wall of the annular guide 4 and developed into a flat sheet by the iron-shaped guide 5 and the rod-shaped straight guide 6. And wound up on a reel 8. The cooling of the sheet was performed by passing warm water of 50 ° C. into each guide, and the temperature was controlled while controlling the ambient temperature so that the discharged sheet would not be cooled rapidly.

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. It was a double-sided lenticular lens sheet. The obtained double-sided lenticular lens sheet was arranged on the observation side, and the Fresnel lens sheet manufactured by the casting method was arranged on the light source side to obtain a three-dimensional image screen. When the extinction degree of the obtained screen was measured in accordance with the method described above, the extinction degree when the polarization axis of the first polarizing film on the light source side was perpendicular was 20.9 dB,
The extinction degree when the polarization axis of the first polarizing film was 45 degrees was 17.4 dB. When a stereoscopic image was observed using this screen, a stereoscopic image with a sense of realism without discomfort was observed, and an image with high contrast was obtained.

Example 2 Methyl methacrylate resin (Acrypet VH manufactured by Mitsubishi Rayon Co., Ltd.) was added as a material for the light-transmitting strand, and 2% by weight of carbon black was added to methyl methacrylate resin (MF manufactured by Mitsubishi Rayon Co., Ltd.) as a material for the light absorbing portion. A double-sided lenticular lens sheet was obtained in the same manner as in Example 1 except that the mixed melt thus obtained was used. The obtained double-sided lenticular lens sheet was arranged on the observation side, and the Fresnel lens sheet manufactured by the casting method was arranged on the light source side to obtain a three-dimensional image screen. When the extinction degree of the obtained screen was measured in accordance with the above-described method, the extinction degree when the polarization axis of the first polarizing film on the light source side was perpendicular was 21.
3 dB, and the extinction degree when the polarization axis of the first polarizing film was 45 degrees was 18.9 dB. When a stereoscopic image was observed using this screen, a stereoscopic image with a sense of realism without discomfort was observed, and an image with high contrast was obtained.

Example 3 On the front surface of the screen obtained in Example 1, a front plate having a polarizing film having a polarization degree of 90 attached to a transparent acrylic plate so as to match the polarization axis of the projected light was installed. When a stereoscopic image was observed using this screen, a stereoscopic image with a sense of realism without discomfort was observed, and an image with extremely high contrast was obtained.

Comparative Example 1 A lenticular lens sheet was produced by hot press molding at a temperature of 110 ° C. using a 3 mm thick acrylic sheet extruded from a methyl methacrylate resin (Acrypet MD manufactured by Mitsubishi Rayon Co., Ltd.) using an extruder. did. A black ink was applied to the obtained lenticular lens sheet by screen printing to form a light absorbing portion.

The obtained lenticular lens sheet was placed on the observation side, and the Fresnel lens sheet produced by the casting method was placed on the light source side to obtain a three-dimensional image screen. When the extinction degree of this screen was measured according to the method described above, the extinction degree when the polarization axis of the first polarizing film on the light source side was perpendicular was 12.4 dB, and the polarization axis of the first polarizing film was The extinction degree when set to 45 degrees is 6.0d
B. When using this screen to observe a stereoscopic image, the image partially changed to rainbow color,
The stereoscopic images also felt quite strange.

Comparative Example 2 A front plate in which a polarizing film having a polarization degree of 90 was attached to a transparent acrylic plate so as to match the polarization axis of the projected light was installed on the front surface of the screen obtained in Comparative Example 1. When a stereoscopic image was observed using this screen, a rainbow pattern was generated on the entire screen and it was very difficult to see, and the image was very poor in color uniformity.

[0027]

The three-dimensional image screen of the present invention provides an excellent three-dimensional image having a high contrast and a sense of realism without a sense of incongruity by setting the extinction degree in the linearly polarized light state within a specific range. You can do it.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus used for manufacturing a projection screen of the present invention.

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

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

FIG. 4 is a sectional view showing a part of the double-sided lenticular lens sheet of the present invention.

[Explanation of symbols]

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

Claims (3)

[Claims] 1. A screen comprising a lenticular lens sheet having a lenticular lens formed on at least one surface, wherein a parallel luminance in a linearly polarized light state is represented by Lh, and a vertical luminance is represented by Lv.
A three-dimensional image screen, wherein the degree of extinction represented by the formula is 15 dB or more. Extinction degree (dB) = 10 × log ₁₀ (Lh / Lv) (1) 2. The three-dimensional image screen according to claim 1, wherein the lenticular lens sheet is a double-sided lenticular lens sheet having lenticular lenses formed on both a light incident surface and a light exit surface. 3. The lenticular lens sheet according to claim 1, wherein a light absorbing portion is formed in a non-light-collecting area of the lenticular lens formed on a light exit surface side of the lenticular lens sheet so as to protrude from the lenticular lens surface. Alternatively, the stereoscopic image screen according to 2.