JP2009047971A - Projection screen and manufacturing method for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection screen which is highly transparent in a certain range, has high color reproducibility on a screen front face, and is capable of high luminance projection, and to provide a manufacturing method for the projection screen. <P>SOLUTION: The projection screen 11 (recording medium 100) reproduces a video by using, as emission light, video light projected by the video projection device. Also, the projection screen 11 scatters light from front within a set angle but transmits light other than this light. The projection screen 11 is obtained by irradiating the recording medium 100 with exposure light in screen recording via at least a hologram or an optical film 71 which has a louver structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projection screen for projecting using a projector, and a method for manufacturing the same.

There has already been proposed a hologram display device that can simultaneously observe an image projected on a screen by a projector and a background on the back of the screen. (Patent Document 1)
By using such a hologram screen device, it is possible to project an advertisement video or the like on the show windows of various showrooms such as department stores and underground shopping streets. In this case, an image can be presented without obstructing the observation of exhibits in the showroom. Such a hologram screen can also be used as a head-up display for various moving objects such as automobiles.

In order to make it possible to observe the video reproduced while seeing through the background, which is a feature of the display device, it is possible to observe a clear background with excellent transparency and little cloudiness. A method for manufacturing a hologram screen has been proposed. (Patent Document 2)
In this manufacturing method, the haze ratio of the screen can be adjusted by changing the exposure intensity ratio between the object light that is diffused light obtained from the light diffuser and the reference light that is non-diffused light.
JP-A-9-114354 JP 2000-75139 A

  However, since the video reproduced on the hologram screen produced by this method shows through the background, the projected video is inevitably low in contrast and difficult to see. As a countermeasure, when the haze rate is increased, the background cannot be seen.

  In this way, conventional projection screens have been set so that the haze ratio is as high as possible and the contrast is set as high as possible. However, such projection screens are conspicuous in opacity and projected. It is difficult to observe a clear background through the screen, and there is a problem that it makes the viewer feel uncomfortable.

  The present invention according to the present invention is capable of observing a high-contrast image on the projection screen without impairing the transparency of the projection screen, and having transparency, and the projection screen. An object is to provide a manufacturing method.

  In order to solve the above-mentioned problems, the inventors of the present invention have intensively studied. As a result, the projection screen has a function having both transparency and diffusivity, and when viewed from the front, the image is diffused and has high contrast. The present invention has been completed by conceiving that the above problem can be solved by making the background portion transparent and transparent when the angle is slightly changed.

  The projection screen according to claim 1 reproduces an image (a two-dimensional image or a three-dimensional image) by using the image light projected from the image projection device as emitted light, and is within an angle set from the front. It is characterized by scattering light but transmitting other light.

  According to such an invention, when projecting from a (screen) image projection device, it is possible to scatter and diffract light from the front direction and confirm the projected image with good contrast. However, when looking into the projection screen surface from a range that exceeds the set angle, the projection screen is set so that it is transparent and allows the background scene to be observed. In addition, it is possible to obtain a sense of transparency when the sharpness and angle of the image are changed by the projection light from the image projection device and the light from the outside.

In the projection screen according to claim 2, the set angle is within ± 20 degrees from the normal direction of the front surface, and the transmittance at 0 degrees (front normal direction) is 30% or less. It is characterized in that the transmittance when the temperature exceeds 35% is 35% or more.
Since the projection screen of the present invention observes the projected image in the front, the transmittance at the front is as low as 30% or less, especially exceeding the set angle range from the front (± 20 degrees from the normal direction of the front). When viewed, the transmittance is 35% or more and it looks transparent.
According to such a projection screen, an image is confirmed within a limited range, but normally (outside the range) is in a transparent state, and an impression that the image floats in space can be obtained. it can.

Further, as in the projection screen according to claim 3, when the set angle is within ± 15 degrees from the normal direction of the front, and the transmittance at 0 degrees is 30% or less and exceeds 30 degrees The transmittance is preferably 60% or more.
Such a projection screen has a particularly narrow set angle range from the front (± 15 degrees from the normal direction of the front), and the transmittance is 60% or more when viewed beyond the range of ± 30 degrees from the normal. Looks transparent.
According to such a projection screen, an image is confirmed in a more limited range, but normally (outside the range) is more transparent, and the image appears to float in space. You can get strong.

As described in claim 4, the projection screen is preferably prepared by exposing a recording medium obtained by applying a refractive index modulation type photopolymer composition to a substrate. In such a case, if recording is performed using a diffusion plate or the like, the portion becomes cloudy.
By using a photopolymer photosensitive material (a photopolymer composition coated on a substrate, etc.) as a photosensitive material necessary for the production of a projection screen, it is possible to provide a projection screen that is even more transparent, has high brightness, and has no brightness unevenness. It becomes possible.
According to such an invention, since a photopolymer photosensitive material is used as a photosensitive material for dimming the screen, it is possible to obtain a screen that does not contain particulate components and is excellent in transparency and diffraction efficiency. In addition, it is possible to record the light control conditions without the need for wet development processing, and the film shrinkage due to the polymerization shrinkage of the polymer contained in the photopolymer photosensitive material is also constant. As compared with the case of recording using a silver salt photosensitive material, the film thickness distribution becomes uniform, and as a result, the entire screen system has a uniform brightness.

  The projection screen according to claim 5 is manufactured by a manufacturing method in which a photopolymer photosensitive material that generates a refractive index distribution by exposure is exposed through an optical film having a louver structure. . By using an optical film with a louver structure, it is possible to limit the field of view on the screen surface, and by adjusting the exposure conditions, it is possible to arbitrarily set transparency, haze ratio, etc. at the viewing angle It has the advantage of becoming. Compared with the case where an optical film having a louver structure is used directly at the time of projection, the boundary between the transparent part and the opaque part becomes gentle, and a clear image can be presented.

The method for producing a projection screen according to claim 6 includes a step of exposing a photopolymer photosensitive material that generates a refractive index distribution by exposure through at least one of an optical film having a hologram or a louver structure. To do.
As the optical film having a louver structure, a commercially available film used for blindfolding may be used. By exposing such an optical film or hologram on a photopolymer photosensitive material, it is possible to limit the field of view on the screen surface. That is, when viewed from the front, an image with high contrast can be observed by diffusing, but if the angle is changed a little, it is possible to manufacture a projection screen that can be transparent and the background portion can be observed. By adjusting the exposure conditions, it is possible to arbitrarily set transparency, haze ratio, etc. at the viewing angle.

According to a seventh aspect of the present invention, there is provided a method for producing a projection screen, in which interference light exposure is performed on a photosensitive material with object light that is diffused light obtained by a light diffuser and reference light that is non-diffused light. The reference light is irradiated through a combination lens that uniformizes the local distribution of the intensity of the light.
In this way, it is possible to make the exposure intensity of the reference light uniform within the surface of the photosensitive material. As a result, it is possible to produce a uniform projection screen with no luminance unevenness in the screen surface. In addition, unlike a single lens, a combination lens is a combination of a plurality of lenses so as to eliminate the aberration of the lens. Therefore, the reference light at the time of screen production does not include information on the aberration of the lens. Therefore, when the screen is irradiated with projection light from the image projection apparatus, that is, reproduction illumination light, a projection screen free from luminance unevenness and chromatic aberration can be obtained.

According to the present invention, it is possible to obtain a high-brightness projection screen that has arbitrary transparency and has no luminance unevenness.
With the projection screen according to the first aspect, a uniform and clear projected image free from unevenness in brightness and aberration can be obtained in front of the screen surface, and transparency can be obtained by changing the field of view.
The projection screen according to the second aspect of the present invention can further achieve both an image with high light source utilization and good visibility and transparency.
Since the projection screen according to the third aspect is visually recognized in a narrow range, further transparency can be obtained.
The projection screen according to the fourth aspect of the present invention is further excellent in image visibility and light source utilization while having transparency.
In the projection screen according to the fifth aspect, it is possible to limit the field of view on the screen surface, and the transparency, the haze ratio, and the like at the field angle can be arbitrarily set.
The method for manufacturing a projection screen according to claim 6 makes it possible to produce a projection screen with high brightness without any luminance unevenness while having arbitrary transparency. It is also possible to set a field of view restriction on the screen surface, and to arbitrarily set the transparency at the viewing angle, the haze ratio, and the like.
The method for manufacturing a projection screen according to claim 7 makes it possible to manufacture a projection screen free from luminance unevenness and chromatic aberration.

  Hereinafter, an embodiment of a projection screen according to the present invention will be described with reference to the accompanying drawings as appropriate.

<Optical system for projection screen photography>
FIG. 1 is a diagram showing an outline of an optical system for hologram screen photography according to an embodiment of the present invention (hereinafter referred to as “projection screen photography optical system” as appropriate). The projection screen photographing optical system 1 will be described with reference to FIG. First, the photosensitive material (photopolymer photosensitive material in this example) oscillates a wavelength having sensitivity, and a beam is oscillated from the laser 10 having sufficient coherence. This is guided to the beam splitter 30 by the mirror 20. By dividing the light by the beam splitter, the object light LO and the reference light LR can be obtained with an arbitrary intensity ratio.

  In FIG. 1, light LO that goes straight to the mirror 21 is incident on the objective lens 41 and is subjected to spatial filtering using the pinhole 51 to cut unnecessary stray light and scattered light. The objective lens 41 preferably has a large magnification (about 20 times) in order to allow diffused light having a uniform intensity as much as possible within the surface of the photosensitive material, but is 5 times when the laser output is insufficient. It is preferable to use a lens of about 10 times. The spatially filtered light is incident on the light diffuser 70. The light diffuser 70 can be a diffuser plate such as ground glass. The area of the light diffuser 70 used at this time is preferably about 1/4 to 2 times that of the photosensitive material (approximately the same area as the recording medium 100 in FIG. 1, see FIG. 3), and if it is too small, the viewing angle becomes too narrow. Or inconsistent object light intensity. On the other hand, if it is too large, it will lead to an increase in interference between unnecessary diffused lights. The aperture 61 is used in order to prevent unnecessary light that is magnified by the objective lens 41 and not incident on the light diffuser 70 from entering the photosensitive material (recording medium 100) other than the originally intended light path. It is preferable to cut them.

  In FIG. 1, light LR traveling straight from the beam splitter 30 to the mirror 22 is incident on the objective lens 42 and is subjected to spatial filtering in the same manner as the object light LO using the pinhole 52 to cut unnecessary stray light and scattered light. . The objective lens 42 preferably has a high magnification (about 20 times) in order to make the light having a uniform intensity as much as possible within the surface of the photosensitive material. It is preferable to use a lens of about 10 times. The spatially filtered light is incident on the collimator lens 80 to obtain parallel light. Subsequently, the collimated light is incident on the zoom lens (combination lens) 90, whereby reference light having uniform intensity and no aberration is obtained. At this time, unnecessary light that does not enter the zoom lens 90 among the parallel light may be cut using the aperture 62 in order to prevent the light from entering the photosensitive material (recording medium 100) other than the original light path. preferable.

  A zoom lens 90 used to obtain reference light with uniform intensity and no aberration will be described. FIG. 2 shows an example of the configuration of the zoom lens 90, which is the same combination lens used in a video projector. In FIG. 2, the parallel light L <b> 1 enters the biconcave lens 110. As a result, the aberration is corrected and then incident on the achromat lens 210, so that the light can be expanded without generating an aberration. An achromatic lens is a lens in which a convex lens and a concave lens having different refractive indexes and dispersion rates are bonded together. Instead of an achromat lens, a magnifying lens in which aberration is suppressed, such as a two-group three-lens in which a convex lens is further combined with a convex lens, or an apochromatic lens, may be used. This series of aberration correction and enlargement processes is performed through another pair of biconcave lens 120 and achromatic lens 220 with the diaphragm 300 interposed therebetween. Finally, by passing through the concave lens 400, it is possible to obtain enlarged light L2 having a short focus. In this example, in order to increase the light source utilization rate, the same combination of zoom lenses as those used during reproduction are used when producing the hologram screen. However, the zoom lenses are of course not limited to the above combinations. Any other lens may be used as long as the light can be enlarged without generating aberration.

In FIG. 1, when the object light LO and the reference light LR are incident on the photosensitive material (recording medium 100), assuming that the angle formed by their optical axes is θ, a preferable range of θ is generally 20 ° to 70. °. The exposure light intensity ratio between the object light LO and the reference light LR is preferably a reference light intensity of 2 to 10 when the object light intensity is 1. More preferably, the reference light intensity is in the range of 4 to 8 with respect to the object light intensity 1. Incidentally, the light amount of the laser beam, if indicated by the product of the light intensity and the irradiation time, preferably 0.1~1,000mJ / cm ^2, more preferably 1 to 100 mJ / cm ^2.

  The configuration and installation of the recording medium 100 will be described with reference to FIG. The recording medium 100 includes a substrate 1A, a recording layer 1B made of a photosensitive material, and a protective layer 1C. The object light LO and the reference light LR are preferably incident from the substrate 1A made of a material (eg, glass) having no optical anisotropy. Further, as the protective layer 1C of the recording layer 1B, in order to prevent reflected light at the interface between the protective layer 1C and air, it is more preferable to use a layer colored so as to absorb light having a laser oscillation wavelength. .

<Photosensitive material>
The photosensitive material according to this embodiment is not particularly limited as long as it can form an image in response to light stimulation. However, the photosensitive material is mainly composed of a refractive index modulation type photopolymer composition, and has a coherency of 2. Only by a recording process of recording interference fringes by exposing with interference of a light beam, a difference between the refractive index of the exposed part and the refractive index of the unexposed part causes a refractive index change of at least 0.001 or more. It is preferable to use it. Further, it is preferable that a wet development process for amplifying the difference in refractive index is unnecessary. Dry development processing by light, heat, or the like can be used as necessary.

  Furthermore, as a photopolymer composition, (A) a radical polymerizable unsaturated doublet capable of recording the intensity distribution of light and darkness of interference fringes obtained by causing interference of light having excellent coherence as a large change in refractive index. Those containing a radical polymerizable monomer containing at least one bond and (B) a binder polymer and / or (C) a cationic polymerizable monomer are preferably used.

  As a more preferred photopolymer composition, the polymerization of the radical polymerizable compound (A) is initiated by irradiation with interference fringes obtained by interference of coherent first light having a visible light wavelength region (D). When containing a photoradical polymerization initiator, a photosensitizing dye that sensitizes the photoradical polymerization initiator (D), and a cationically polymerizable compound (C), a wavelength region different from that of the first light And (F) a photocationic polymerization initiator that initiates the polymerization of the cationically polymerizable compound (C) by irradiation with a second light having a refractive index of the radically polymerizable compound (A), and the binder polymer (B) And / or a photopolymer composition adjusted to be larger than the weighted average value of the refractive index with the cationically polymerizable compound (C).

  The cationic photopolymerization initiator (F) initiates polymerization of the cationically polymerizable monomer (C) by irradiation with the second light, but is sensitive to irradiation of interference fringes obtained by interference with the first light. Is preferably low and does not substantially initiate the polymerization of the cationically polymerizable monomer (C).

Radical polymerizable monomer (A)
The radical polymerizable monomer (A) used in the present invention has compatibility when the composition according to the present invention is prepared together with the binder polymer (B) and / or (C) cationic polymerizable monomer used in the present invention. A wide range of compounds can be used as long as they are present, but the non-gaseous, ie, liquid or solid radically polymerizable compound (A) having a boiling point of 100 ° C. or higher at normal pressure is preferred.
In particular, (meth) acrylic monomers, vinyl monomers, and (meth) allyl monomers having an ethylenically unsaturated double bond are preferred. These may be used alone or in combination of two or more.

Binder polymer (B)
The binder polymer (B) used in the present invention only needs to be compatible with the radical polymerizable compound (A) and the cationic polymerizable compound (C) and can be completely dissolved in the organic solvent. Typical examples include a homopolymer of a monomer having an ethylenically unsaturated double bond, or a copolymer of the monomer and a copolymerizable monomer copolymerizable therewith, a diphenol compound and a dicarboxylic acid compound. Selected from the group consisting of a condensation polymer, a polymer having a carbonate group in the molecule, a polymer having a -SO2- group in the molecule, a cellulose derivative, and a combination of two or more thereof.

Cationic polymerizable monomer (C)
The cationically polymerizable monomer (C) used in the present invention is preferably compatible with any other components, has a refractive index as low as that of the radically polymerizable monomer (A), and is preferably a liquid at normal temperature and pressure. . By using such a cationically polymerizable monomer, the entire composition is sufficiently compatible before hologram recording, but diffusion transfer of the radically polymerizable monomer (A) is likely to occur as hologram recording is started. . By selecting a low refractive index, a large refractive index can be obtained even if only slight separation occurs between the two in the separation from the cationic polymerizable monomer (C) by diffusion transfer of the radical polymerizable monomer (A). A difference (refractive index modulation) can be obtained. The cationic polymerizable monomer (C) is irradiated with a second light (preferably ultraviolet light) having a wavelength region different from that of the first light (preferably visible light), and polymerized by the reaction of the cationic polymerization initiator (F). It is done.

  Specific examples of the cationically polymerizable monomer (B) include compounds having at least one oxirane structure or oxetane structure in one molecule, or both.

Photopolymerization initiator (D)
As the photopolymerization initiator (D), by using the photopolymerization initiator (D) alone or in combination with the photosensitizing dye (E), He—Ne (wavelength 633 nm), YAG (wavelength 532 nm), Ar ( Those capable of generating radicals by absorbing light emitted from a laser light source such as wavelengths 515 and 488 nm and He—Cd (wavelength 442 nm) can be suitably used. Examples of such photopolymerization initiators include carbonyl compounds, amine compounds, arylaminoacetic acid compounds, organic tin compounds, alkylaryl boron salts, onium salts, iron arene complexes, trihalogenomethyl-substituted triazine compounds, organic peroxides. , Bisimidazole derivatives, titanocene compounds, and combinations of these photopolymerization initiators and photosensitizing dyes.

Photosensitizing dye (E)
As the photosensitizing dye (E), mihiraketone, acridine yellow, merocyanine, methylene blue, camphorquinone, eosin, decarboxylated rose bengal and the like can be suitably used. As the photosensitizing dye, any substance that absorbs light in the visible region may be used. Besides the above, for example, cyanine derivatives, merocyanine derivatives, phthalocyanine derivatives, xanthene derivatives, thioxanthene derivatives, acridine derivatives, porphyrin derivatives, Coumarin derivatives, base styryl derivatives, ketocoumarin derivatives, quinolone derivatives, stilbene derivatives, oxazine derivatives, thiazine dyes, and the like can also be used. These photosensitizing dyes may be used alone or in combination of two or more.

Organic solvent The organic solvent is effective for improving the film formability and the like in addition to adjusting the viscosity and compatibility of the photopolymer photosensitive material. For example, acetone, xylene, toluene, methyl ethyl ketone, tetrahydrofuran, benzene, methylene chloride, Dichloromethane, chloroform, methanol and the like can be used.

<Preparation of photopolymer composition>
To prepare the photopolymer composition according to this embodiment described above, a radically polymerizable compound (A), a binder polymer (B) soluble in an organic solvent and / or a cationically polymerizable compound (C), What is necessary is just to put a photoinitiator (D and / or F) etc. in organic-resistant solvent containers, such as a glass beaker, and to stir the whole. In this case, in order to promote the dissolution of the solid component, it may be heated as long as the composition is not denatured.

<Method for producing photopolymer photosensitive material>
In the photosensitive material (before recording) using the photopolymer composition according to the present embodiment, the photopolymer composition is applied to one surface of the substrate, and the recording of a two-layer structure including the resulting coating film (recording layer) and the substrate is recorded. It is obtained by making a medium (not shown). Alternatively, as shown in FIG. 3, as a preferred embodiment, a recording medium 100 having a three-layer structure may be manufactured by covering a recording layer 1B on a substrate 1A with a film-like, sheet-like or plate-like protective material 1C. good.

  When an organic solvent is used in the preparation process of the photopolymer composition, the radical polymerizable compound (A), the binder polymer (B) and / or the cationic polymerizable compound (C) soluble in the organic solvent, and a photopolymerization initiator ( If the above optional additional components including D and / or F) are dissolved in an organic solvent (solvent), the resulting solution is applied onto a substrate, and then the solvent is stripped to form a recording layer. good. When the recording layer is covered with a protective material (see FIG. 3), it is preferable to remove the organic solvent by air drying or evaporation under reduced pressure before coating the protective material.

  As a substrate on which the photopolymer composition is applied, an optically transparent material such as glass or quartz, or a transparent resin such as polyethylene terephthalate (PET), acrylic resin, polycarbonate, polyolefin, or alicyclic polyolefin is used. Can do. Preferably, glass having no optical anisotropy or alicyclic polyolefin is used. The thickness of the substrate is preferably 0.02 to 10 mm. The substrate is not necessarily flat, and may be bent, curved, or have a concavo-convex structure on the surface. The protective material can also be formed from the same optically transparent material as the substrate. When the protective material is peeled off after screen recording, it is preferable to use a material colored so as to absorb light having the oscillation wavelength of the laser used. The thickness of the protective material is preferably 0.02 to 10 mm.

  As a coating method of the photopolymer composition, gravure coating, roll coating coating, bar coating coating, spin coating coating or the like can be used. Then, coating is performed so that the thickness of the recording layer after removal of the solvent is 1 to 500 μm, preferably 5 to 50 μm.

<Light source for recording>
As a light source for recording according to this embodiment, light emitted from a light source was irradiated to a photopolymerization initiator contained in a photopolymer photosensitive material or a photopolymerization initiator system composed of a combination of a photopolymerization initiator and a photosensitizing dye. In this case, any material may be used as long as it induces polymerization of the polymerizable compound with electron transfer.

  As described above, the laser light source 10 can be used as a recording light source according to the present embodiment. Laser light emitted from the laser light source has a single wavelength and has coherence (coherence), and therefore can be suitably used for hologram recording (interference fringe recording). As a more preferable light source, a light source that is more excellent in coherence, for example, an optical element such as an etalon mounted on the laser light source and the frequency of the single wavelength is made a single frequency can be exemplified.

  As a typical laser light source, a laser light source having an oscillation wavelength of 200 to 800 nm, specifically, Kr (wavelength 647 nm), He—Ne (wavelength 633 nm), Ar (wavelength 514.5 nm, 488 nm), YAG (wavelength 532 nm) And a laser light source such as He-Cd (wavelength 442 nm). These laser light sources may be used alone or in combination of two or more. The laser light source may be a type that oscillates continuous light or a type that pulsates at a constant or arbitrary interval.

  Hereinafter, the features of the present invention will be further clarified by showing examples.

<Preparation of screen recording medium>
1.08 g of 9,9-bis [4- (3-acryloyloxy-2-hydroxy) propoxyphenyl] fluorene (single refractive index: 1.63) (weight percentage based on the total composition: 28.1 wt%), Ethylene glycol diglycidyl ether (refractive index of simple substance: 1.46) 1.05 g (27.4% by weight), polymethylmethyl methacrylate (refractive index of simple substance: 1.49) 1.25 g (32.6% by weight) 3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl) benzophenone 0.25 g (6.5 wt%), cyanine dye (2,5-bis [(4-diethylamino) -2- Methylbenzylidene] cyclopentanone) 0.0082 g (0.2 wt%), triarylsulfonium compound (Asahi Denka Kogyo Co., Ltd., “SP-170”, salt hexa Le Oro antimonate) 0.2 g (5.2 wt%), and acetone 5g mixed at room temperature as a solvent, to prepare a photopolymer composition.

  The adjusted photopolymer composition is applied on one side of a 200 mm × 250 mm glass substrate 1A (MATSUNAMI MICRO SLIDE GLASS) by spin coating so that the thickness after drying is 20 to 25 μm, and then heat-treated. Then, the solvent was removed from the coating layer to prepare a recording medium having a two-layer structure composed of the substrate 1A and the recording layer 1B.

  Further, a three-layer photopolymer recording medium (photopolymer photosensitive material) 100 (see FIG. 3) was produced by coating a PET film having a thickness of 50 μm as the protective material 1C on the recording layer 1B.

<Preparation of Projection Master Hologram 101 (First Step)>
A laser beam oscillated from a YAG (wavelength 532 nm) laser light source 10 is split by a beam splitter 30, and one of the lights is spatially filtered using an objective lens 41 (20 times) and a pinhole 51 (20 μm). Was made incident on a light diffuser 70 in which three sheets of double-sided ground glass (# 1000) were stacked, and the emitted light (diffused light) therefrom was used as object light LO (see FIG. 1). The intensity of the object light LO was 20 μW / cm ² . The other light split by the beam splitter 30 is spatially filtered using the objective lens 42 (10 ×) and the pinhole 52 (20 μm), converted into parallel light through the collimator lens 80, and the zoom lens 90 (see FIG. 2). ), And the light emitted therefrom was used as reference light LR. The reference light intensity was almost constant (60 to 80 μW / cm ² ) regardless of the location of the photosensitive material. Incidentally, the angle θ formed by the optical axis of the reference light LR and the object light LO is set to 135 degrees, and the optical axis of the reference light LR is set to an incident angle of 45 degrees with respect to the photosensitive material surface (FIGS. 1 and 4). (See (a)). The exposure energy was 8 J / cm ² and the exposure time was 80 seconds.

<Production of Projection Screen 11 (Example 1) (Second Step)>
Using the master hologram 101 manufactured as described above, the object light (LO) and the reference light (LR) are transmitted through the master hologram 101 as shown in FIG. Photosensitive material) was exposed.
At this time, when the object light (LO) is incident on the master hologram, it is exposed to the recording medium (100) as the reproduction illumination light LI. Therefore, the recording medium (100) is recorded as interference light between the reference light and the reproduction light (LI) of the master hologram. The exposure was performed so that the optical axis of the reference beam (LI) was perpendicular to the master hologram surface and the photopolymer photosensitive material surface. Further, exposure was performed so that the angle formed by the object light (LO) and the master hologram (101) was 45 degrees.
The exposure energy was 8 J / cm ² and the exposure time was 80 seconds.
As shown in FIG. 4C, the projection screen 11 thus produced scatters only light that enters vertically (with an incident angle of 0 degrees), so that the viewer can visually recognize the light (image). When the angle is set, it becomes transparent and you see the background instead of the video.

<Production of Projection Screen 12 (Example 2)>
For the projection screen 11 except that the recording medium 100 was exposed through a light control film (trade name, manufactured by Sumitomo 3M) having a visible angle of 60 degrees behind the master hologram 101 during the production of the projection screen 11. A projection screen 12 was produced in the same manner as the screen 11.

<Production of Projection Screen 13 (Example 3)>
The projection screen 11 is projected in the same manner as the projection screen 11 except that the optical axis of the recording light at the time of recording the master hologram 101 and the screen is set so that the incident angle is 20 degrees with respect to the photosensitive material surface. A screen 13 was prepared.

<Production of Projection Screen 14 (Example 4)>
A projection screen photographing optical system 2 as shown in FIG. 5 is used, and laser light oscillated from a YAG (wavelength 532 nm) laser light source 10 is spatially transmitted using an objective lens 41 (20 times) and a pinhole 51 (20 μm). The filtered light is converted into parallel light through the collimator lens 80 and is incident on the zoom lens 90 (see FIG. 2), and the light emitted therefrom is used as recording light. The recording light was exposed to the screen recording medium 100 (photopolymer photosensitive material) through a louver-shaped optical film 71 (“Lumisty” manufactured by Sumitomo Chemical Co., Ltd.) having an opaque range of ± 15 degrees in the vertical direction. At this time, exposure was performed so that the optical axis of the recording light was perpendicular to the optical film surface and the photopolymer photosensitive material surface. The exposure energy was 8 J / cm ² and the exposure time was 80 seconds.
Note that the optical film 71 is separated from the recording medium 100 in FIG.

<Production of Projection Screen 15 (Example 5)>
In the production of the projection screen 14, a louver-shaped light control film (not shown) having a visible angle of 60 degrees is applied to the louver-shaped optical film 71 (lumisty) whose upper and lower ranges of ± 15 degrees are opaque. A projection screen 15 was produced in the same manner as the projection screen 14 except that the exposure was performed so as to be aligned.

Comparative example

<Production of hologram recording medium>
The method for producing the hologram recording medium 100 was the same as that in the example.

<Production of Projection Screen 16 (Comparative Example 1)>
FIG. 6 is a diagram showing an outline of a projection screen photographing optical system 1 ′ for photographing the projection screen 16 according to a comparative example of the present invention. The same elements as those in the projection screen photographing optical system 1 are denoted by the same reference numerals.
A laser beam oscillated from a YAG (wavelength 532 nm) laser light source 10 is split by a beam splitter 30, and one of the lights is spatially filtered using an objective lens 41 (20 times) and a pinhole 51 (20 μm). Was incident on a light diffuser 70 in which three sheets of double-sided ground glass (# 1000) were stacked, and the diffused light (emitted light) therefrom was used as object light LO. The intensity of the object light LO was 20 μW / cm ² . The other light split by the beam splitter 30 was spatially filtered using the objective lens 42 (40 ×) and the pinhole 52 (20 μm), and the emitted light was used as the reference light LR ′. Incidentally, the angle θ formed by the optical axis of the reference beam LR ′ and the object beam LO is set to 45 degrees, and the optical axis of the reference beam LR ′ is set to an incident angle of 45 degrees with respect to the photosensitive material surface (see FIG. 6). ). The exposure energy was 8 J / cm ² and the exposure time was 80 seconds.

<Evaluation of projection screen>
Using the projection screens 11 to 16 produced as described above in Examples and Comparative Examples, the illumination light is irradiated as shown in FIG. 7, and an optical power meter 500 (OPTICAL POWER / ENERGY METER, manufactured by PHOTODYNE) is used. , MODEL 66XLA) was used to measure the transmitted light intensity (transmittance: T%) at an angle to the incident light.

The results are shown in Table 1. Examples 1 to 5 refer to the projection screens 11 to 15 described above, and Comparative Example 1 refers to the projection screen 16.

  As can be seen from Table 1, the projection screen of the example has a low transmittance in the vicinity of the front surface (less than 30% at 0 degrees), and the transmittance is increased by changing the angle slightly (35% or more at 20 degrees, 30 degrees). In the normal state, it looks transparent, but only the point on the front looks beautiful. Further, since the transmittance at the front is low, the contrast of the video is very high. Further, since a projection lens is used at the time of recording, a good image can be obtained with very little color unevenness and light amount unevenness.

  When the images were actually projected on the projection screens obtained in the examples and comparative examples, the projection screens obtained in the examples provided clear images with clear, high-resolution images. In the projection screen obtained in the example, the contrast was low and a clear image could not be obtained.

  The projection screen of the present invention can be used for reproducing a two-dimensional image, and also for reproducing a three-dimensional image by combining with a lens.

FIG. 1 is a top view of a projection screen photographing optical system 1 for producing a projection screen 11 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of the lens configuration of the zoom lens 90 used in the production of the projection screen 11 according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing the configuration and installation of the photosensitive material (recording medium 100) in the production of the projection screen 11 according to an embodiment of the present invention. FIG. 4A is a diagram showing a first step of a production method for producing a projection screen 11 according to an embodiment of the present invention, and FIG. 4B shows a second step of the production method. FIG. 4C is an explanatory diagram of the function of the projection screen 11. FIG. 5 is a top view of the optical system 2 for producing the projection screens 14 and 15 according to another embodiment of the present invention. FIG. 6 is a top view of a projection screen photographing optical system 1 ′ for producing a projection screen 16 as a comparative example. FIG. 7 is a diagram showing a method of measuring the transmitted light intensity of the projection screens 11 to 16.

Explanation of symbols

1 ・ 2 ・ 1 ′ Projection Screen Imaging Optical System 11 to 16 Projection Screen 70 Diffuser Plate 71 Louver-shaped Optical Film 90 Zoom Lens (Combination Lens)
100 Recording medium 101 Master hologram 1A Substrate 1B Recording layer (photopolymer photosensitive material)
1C Protective material LO Object light LR Reference light LI Reproduction illumination light

Claims (7)

While reproducing the image by using the image light projected from the image projection device as the emitted light,
A projection screen characterized by scattering light within an angle set from the front but transmitting other light.   The set angle is within ± 20 degrees from the normal direction of the front, the transmittance at 0 degrees is 30% or less, and the transmittance when it exceeds 20 degrees is 35% or more. The projection screen according to claim 1.   The set angle is within ± 15 degrees from the normal direction of the front, the transmittance at 0 degrees is 30% or less, and the transmittance when it exceeds 30 degrees is 60% or more. The projection screen according to claim 1 or 2.   The projection screen according to claim 1, wherein the projection screen is produced by exposing a recording medium obtained by applying a refractive index modulation type photopolymer composition to a substrate.   The projection screen according to claim 1, wherein the projection screen is manufactured by exposing a photopolymer photosensitive material that generates a refractive index distribution by exposure through an optical film having a louver structure. Regarding the manufacture of a projection screen for reproducing an image by using the image light projected from the image projection device as emitted light,
A method for producing a projection screen, comprising a step of exposing a photopolymer photosensitive material that generates a refractive index distribution upon exposure through at least one of an optical film having a hologram or a louver structure.   When the object light, which is diffused light obtained by the light diffuser, and the reference light, which is non-diffused light, are subjected to interference exposure on the photosensitive material, they are referenced through a combination lens that uniformizes the local distribution of light intensity. The method for manufacturing a projection screen according to claim 6, wherein light is irradiated.

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