JP2005165252A - Optical functionality diffusion board, reflection screen and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical functionality diffusion board capable of improving contrast performance so that an image can be clearly observed, a reflection screen and a method for manufacturing the reflection screen. <P>SOLUTION: The optical functionality diffusion board is provided with a diffusion board 113 having ruggedness on the surface and an optical thin film 114 having a refractive index lower than that of the diffusion board 113 and formed on the surface of the diffusion board 113. The optical thin film 114 is formed so that the rugged shape is reflected to the surface and film thickness is gradually thickened from the projected part to the recessed part on the surface of the diffusion board 113. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical functional diffuser, a reflective screen, and a method for manufacturing the same.

  Front projection systems that project image light emitted from a projector onto a reflective screen are increasing in popularity as a system that realizes a large screen (100 inches or more) at a relatively low cost. Recently, this increase has been accelerated especially by the appearance of high-brightness and low-priced liquid crystal projectors.

  However, the front project system, unlike the rear projection system that projects image light from the back of the transmissive screen, is easily affected by external light, and the rear projection system is clearly improved in contrast performance.

  So far, as a reflection type screen for a front projection system, a white mat screen using a white mat as a reflection layer as a reflection layer, a bead screen using retroreflection (for example, see Patent Document 1), and aluminum. A silver screen or the like using a foil as a reflective layer has been proposed.

JP-A-3-53232

  However, the above screens are all screens for improving the brightness. Although the whole screen is bright, the projector light and the external light are equally reflected. Therefore, the brighter the room, the contrast of the image (the ratio of black and white) Tended to decrease.

  The present invention has been made in view of the above problems in the prior art, and provides an optical functional diffuser plate, a reflective screen, and a method for manufacturing the same, which can enhance contrast performance so that an image can be clearly seen. For the purpose.

  The inventors have intensively studied that even under the influence of external light, high gain and high contrast can be obtained by reducing the surface reflection on the diffuser plate on the reflective screen surface and increasing the transmittance. As a result, the present invention was accomplished.

  That is, the present invention provided to solve the above problems comprises a diffusion plate having irregularities on the surface, and an optical thin film having a refractive index lower than that of the diffusion plate on the surface of the diffusion plate. The optical functional diffusion plate is formed so as to reflect the uneven shape on the surface, and is provided so that the film thickness gradually increases from the convex portion to the concave portion on the surface of the diffusion plate.

Here, the unevenness difference of the diffusion plate is preferably 1 μm or more and 30 μm or less.
The film thickness of the optical thin film is preferably 70 nm or more and 110 nm or less at the convex portion, and 100 nm or more at the concave portion and not more than the unevenness difference of the diffusion plate.

The optical thin film is preferably formed from a paint containing a fluororesin, or the optical thin film is preferably formed from a paint containing SiO ₂ fine particles.

  The present invention provided to solve the above-mentioned problems comprises a reflective layer and a light functional diffuser according to any one of claims 1 to 5 on a support in order. A mold screen.

  Here, the reflection layer is a layer of 2n + 1 (n is an integer of 1 or more) in which a first optical film having a high refractive index and a second optical film having a lower refractive index are alternately stacked. It is preferable that the optical multilayer film has a high reflection characteristic with respect to light in a specific wavelength region and a high transmission property in at least a visible wavelength region other than the specific wavelength region.

  Further, it is preferable that the support is transparent and the optical multilayer film is formed on both sides of the support.

Furthermore, the optical multilayer film preferably has a laminated structure in which the outermost layer is formed of the first optical film.
The specific wavelength region may include red, green, and blue wavelength regions.

The first optical film is a film obtained by applying a paint containing metal oxide fine particles, a dispersant, and a binder, and the second optical film is a paint containing a fluororesin or SiO ₂ fine particles. It is preferable that it is a film | membrane obtained by apply | coating.
The fluororesin preferably has a functional group that absorbs energy and causes a curing reaction.

  Moreover, it is good to provide a black light absorption layer in the back side of the said support body.

  This invention provided in order to solve the said subject is a manufacturing method of the reflection type screen which provides a reflection layer and the optical functional diffusion plate as described in any one of Claims 1-5 in order on a support body. The manufacturing method of the optical functional diffusing plate includes a step of forming an optical thin film on the surface of the diffusing plate by dipping.

  According to the present invention, since surface scattering of incident light on the diffusion plate can be suppressed, a high gain, high contrast image can be displayed even in a bright environment (for example, an office, an exhibition hall, a general house). it can.

Embodiments of the present invention will be described below.
(Optical functional diffuser)
An example of the configuration of the optical functional diffuser according to the present invention is shown in FIG.
The optical functional diffusion plate 11 includes a diffusion plate 113 having an uneven surface, and an optical thin film 114 having a refractive index lower than that of the diffusion plate 113 on the surface of the diffusion plate 113. The optical thin film 114 is formed so as to reflect the uneven shape of the diffusion plate 113 on the surface, and is formed so that the film thickness gradually increases from the convex portion to the concave portion on the surface of the diffusion plate 113.

Here, the diffusion function is controlled by making the surface shape of the diffusion plate 113 a circular shape, a rectangular shape, or a rectangular uneven shape.
FIG. 1 shows an example of a diffusion plate 113, which is a light-transmitting or non-light-transmitting base sheet 111 and a bead layer 112 made of a binder and beads coated on the upper surface of the base sheet 111. It is composed of

Among the base sheet 111, as the light transmissive base sheet, an excellent light such as a transparent, milky white transparent plastic film such as polyethylene terephthalate (PET) or polycarbonate (PC), a cloth made of glass fiber, or synthetic paper is used. What has permeability may be used. Also, the light as the non-permeable substrate sheet, the constituent material of the light-transmitting substrate sheet may be used, for example those imparted inorganics were mixed impermeable such as titanium dioxide (TiO ₂₎ .
Further, the thickness of the base sheet 111 is not particularly limited, but is preferably about 10 to 5000 μm in consideration of the usage form as the screen material.

  Examples of beads that can be used for the bead layer 112 include plastic beads (eg, acrylic milky white beads) and colored beads (eg, white plastic beads, white glass beads). Further, the particle size of the beads is not particularly limited, but considering the light reflection efficiency and the like, those having a particle size of about 1 to 100 μm are preferable, and it is preferable to use beads having different particle sizes in a mixed manner.

  The color to be imparted to the beads is preferably white from the viewpoint of reflection efficiency, and as the colorant in this case, a white inorganic pigment such as titanium oxide, talc, zinc oxide or the like can be used. In view of the reflection efficiency of the preparation, titanium dioxide is particularly preferable. Moreover, when mixing and using a transparent bead and a colored bead, the mixture ratio of both considers the reflective effect of a light ray, and the range of 1:99 weight%-99: 1 weight% is preferable.

  As the binder, a synthetic resin (for example, an acrylic copolymer resin or a urethane resin) can be used. The mixing ratio of the beads and the binder is preferably in the range of 5 to 95 parts by weight with respect to 100 parts by weight of the binder in consideration of the light reflection effect and the like.

  The thickness of the bead layer 112 is not particularly limited, but considering the difficulty of coating on the base sheet 111 by a well-known roll coating method, the strength, the light shielding effect, etc., about 10 to 500 μm. Is preferred.

  Furthermore, as an arrangement mode of the beads in the bead layer 112, in consideration of a light diffusion effect or the like, a bead embedded in the binder and a partially embedded bead in the binder are used, and It is preferable that the beads are dispersed on the surface of the base material sheet 111 so that the beads are separated from each other or distributed so as to substantially cover the surface of the base material sheet 111.

  Furthermore, for the purpose of supplementing the reflection efficiency of the reflection type screen of the present invention, a reflection layer can be formed on the other surface of the substrate sheet 111, that is, the surface opposite to the surface on which the bead layer 112 is provided. As the reflective layer, any substance that improves the light reflection efficiency is basically applicable. For example, a reflective layer formed by vapor-depositing a metal such as aluminum or silver, or the metal-deposited reflective layer. In addition, it is possible to apply those in which colored beads are further blended to increase the reflection efficiency.

  In addition, a flame retardant, for example, triphenyl phosphate, polycresyl phosphate, or the like can be further blended for the purpose of imparting flame retardancy to the base sheet, binder and beads constituting the diffusion plate. .

  In addition, the diffusion plate 113 usable in the present invention is a fine plate formed by exposing light scattered in various directions by a diffusing device or a homogenizing device to a photosensitive medium as a speckle pattern and developing it. It may be produced using a simple sculptured surface structure.

  In the diffusion plate shown above, it is preferable that the surface unevenness difference is 1 μm or more and 30 μm or less in order to ensure the light diffusion function as the diffusion plate. The reason why the upper limit is 30 μm is that the viewing angle becomes too narrow when it exceeds this range.

The optical thin film 114 constituting the optical functional diffusion plate 11 is formed so as to reflect the uneven shape of the diffusion plate 113 on the surface, and is provided so that the film thickness gradually increases from the convex portion to the concave portion on the surface of the diffusion plate 113. It is what has been.
Examples of the material constituting the optical thin film 114 include fluorine resin, fine particles such as silica (SiO ₂ ), hollow fine particles, and the like, and a film having a refractive index of 1.45 or less formed by them is particularly preferable.

The optical thin film 114 is for suppressing the surface scattering of the incident light on the optical functional diffuser plate 11, and from an oblique direction in which external light enters along with the projector light incident from the front of the screen. Reduces surface scattering of light.
On the other hand, the optical functional diffusion plate 11 also needs a function of diffusing emitted image light.

Therefore, the optical thin film 114 needs to cover the unevenness of the surface of the diffusion plate 113 and reflect the uneven shape on the surface. The film thickness of the optical thin film 114 for realizing this is 70 nm or more and 110 nm or less at the convex portion. In the recess, it is preferably 100 nm or more and not more than the unevenness difference of the diffusion plate.
More specifically, in FIG. 1, the film thickness d1 in the concave portion of the diffusion plate 113 of the optical thin film 114 (the thickness direction of the base sheet 111, that is, the vertical direction in the figure), the film thickness d2 in the middle region of the irregularities (on the bead layer surface) In contrast, by optimizing the film thickness d3 (the thickness direction of the base sheet 111, that is, the vertical direction in the figure) at the convex portion, the surface reflection by the projector light from the front direction and the external light from the oblique direction is achieved. Is reduced. In particular, for external light from an oblique direction, it is effective to optimize the film thickness d2 in the intermediate region of the unevenness. Here, when an optical thin film is formed by a thin film forming method such as a vapor deposition method, the film thickness can be controlled, but it is difficult to control the film thickness d2 in the intermediate region of the unevenness, and the film thickness is smaller than that of the concave and convex portions. The problem arises that the film thickness is reduced and the film thickness cannot be sufficiently reduced to reduce the surface reflection due to external light. In addition, a recessed part is the most recessed part of the uneven | corrugated surface of the diffusion plate 113, a convex part is the top part, and an intermediate | middle area | region means a part other than that.

  Here, as an appropriate film thickness of the optical thin film 114, when the unevenness | corrugation difference of the surface of the diffusion plate 113 is 1 micrometer, the film thickness d1 in a recessed part has preferable 100 nm-1 micrometer, More preferably, it is 100-150 nm. . Further, the film thickness 3 at the convex portion is preferably 70 to 110 nm, and the film thickness d2 in the intermediate region from the convex portion to the concave portion is preferably 100 to 150 nm. In addition, when the film thickness is smaller than the above film thickness, it is not suitable because surface scattering cannot be sufficiently suppressed.

  In addition, when the film thickness d1 in the concave portion is larger than the uneven height difference on the surface of the diffusion plate 113, that is, when the film thickness is such that the unevenness on the surface of the diffusion plate 113 is buried, the diffusion characteristics are affected. Not suitable for. On the other hand, if the film thickness d3 at the convex portion is larger than the film thickness d1 at the concave portion, this case is also unsuitable because it affects the diffusion characteristics.

(Method for producing optical functional diffuser)
The manufacture of the optical functional diffusion plate includes a manufacturing process of the diffusion plate 113 and a formation process of the optical thin film 114.

(1) Manufacturing Process of Diffusion Plate A diffusion plate 113 having the configuration shown in FIG. 1 is formed by applying a bead coating obtained by mixing the above beads and a binder to the base sheet 111 by a known roll coating method or the like. What is necessary is just to produce by forming.

Further, a diffusion plate manufactured by exposing a speckle pattern to a photosensitive medium may be manufactured by the following process.
(S1) A photosensitive substrate provided with a photosensitive medium on a substrate is prepared, and the photosensitive medium is exposed to laser light (interference light) modulated into a speckle pattern by a diffusing device or the like, and then developed and fixed. Since the area of one exposure area is 1 to several tens of cm ² , in the exposure step, the entire surface of the photosensitive medium is repeatedly exposed while shifting the exposure target portion of the photosensitive medium. When a positive photoresist is used, the exposed area is removed when developed, and the non-exposed area remains as it is. As a result, a photosensitive substrate having a concavo-convex fine engraving surface corresponding to the speckle pattern formed on the surface is obtained.
(S2) For example, an ultraviolet curable epoxy resin is applied to the surface of the photosensitive substrate produced in step s1, and cured to produce a resin mold in which the unevenness of the photosensitive substrate surface is copied.
(S3) Next, a conductive layer is formed on the surface of the resin mold to form a conductive layer, and electroforming is performed using the conductive layer as a cathode to produce a metal master. At this time, a conductive layer made of metal or the like is formed by silver mirror treatment, electroless plating treatment, vacuum deposition treatment, sputtering treatment or the like as the conductive treatment. Moreover, as electroforming, for example, nickel is electrodeposited to a predetermined thickness, and a resin mold is removed from the electrodeposited nickel layer to obtain a metal master for metal electroforming.
(S4) Based on the metal master produced in step s3, a diffusion plate is manufactured by, for example, embossing on a thermoformed plastic film.

As the diffusion device, for example, frosted glass, milk white glass, opaque plastic, chemical etching plastic, lens-like or surface machined plastic, or the like may be used, and cloth and nylon diffuser may be used. Among them, in the case of lens-shaped or surface-machined plastics, the angle of diffused light as a diffuser can be partially controlled by changing the characteristics of the surface texture of the diffuser, so its application compared to other diffusers Wide range.
As the photosensitive medium, for example, dichromated gelatin, photoresist, silver halide or photopolymer may be used.

  Although the example in the case of mass-producing a diffusion plate was shown above, you may use the resin-made type | mold obtained at step s2 as a diffusion plate as it is. Further, the mold may be coated with a reflective material for reflection.

(2) Optical Thin Film Formation Step The optical thin film 114 is formed by applying the following optical thin film paint to the surface of the diffusion plate 113.

  The coating material for optical thin films contains an organic solvent and a binder. The binder is dissolved in an organic solvent, and if necessary, fine particles may be added and dispersed therein.

  The binder is a resin having a functional group that causes a curing reaction in the molecule by radiation such as ultraviolet rays or energy from heat, and a fluorine resin or the like is preferable. It is also preferable to use a polymer whose main chain is fluorine-modified, a polymer whose side chain is fluorine-modified, a monomer containing fluorine, and the like.

Examples of the polymer whose main chain is fluorine-modified include perfluoro main chain perfluoropolyether, perfluoro side chain perfluoropolyether, alcohol-modified perfluoropolyether, and isocyanate-modified perfluoropolyether. In addition, examples of the monomer having fluorine include CF ₂ ═CF ₂ , CH ₂ ═CF ₂ , and CF ₂ ═CHF. Those obtained by polymerizing these monomers and those obtained by converting these monomers into block polymers can also be used.

  Examples of the polymer whose side chain is modified with fluorine include those obtained by graft polymerization with a solvent-soluble main chain, and in particular, polyvinylidene fluoride is a resin that can be used as a solvent because it is easy to handle. Examples of preferred low refractive index thermoplastic polymers. When this polyvinylidene fluoride is used as the low refractive index thermoplastic polymer, the refractive index of the low refractive index layer is about 1.4. To lower the refractive index of the low refractive index layer further, trifluoroethyl acrylate Such a low refractive index acrylate may be added in an amount of 10 to 300 parts by weight, preferably 100 to 200 parts by weight, based on 100 parts by weight of the ionizing radiation curable resin.

The fine particles used in the optical thin film 114 are fine particles of a low refractive index material added as necessary to adjust the refractive index of the optical film after film formation, and LiF (refractive index 1.4). MgF ₂ (refractive index 1.4), 3NaF · AlF ₃ (refractive index 1.4), AlF ₃ (refractive index 1.4), SiOx (1.5 ≦ x ≦ 2.0) (refractive index 1. Ultrafine particles made of materials such as 35 to 1.48) are preferred. Alternatively, hollow fine particles may be included.

Organic solvents include, for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, alcohol solvents such as methanol, ethanol, propanol, butanol, isobutyl alcohol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, lactic acid Examples of ester solvents such as ethyl and ethylene glycol acetate, and fluorine-containing solvents include perfluorobenzene, pentafluorobenzene, 1,3-bis (trifluoromethyl) benzene, and 1,4-bis (trifluoromethyl) benzene. Fluorinated aromatic hydrocarbons, fluorinated alkylamines such as perfluorotributylamine, perfluorotripropylamine, perfluorohexane, perfluorooctane, perfluorodecane, perfluoride Can, perfluoro-2,7-dimethyloctane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1H-1,1-dichloroperfluoropropane, 1H-1,3-dichloro Perfluoropropane, 1H-perfluorobutane, 2H, 3H-perfluoropentane, 3H, 4H-perfluoro-2-methylpentane, 2H, 3H-perfluoro-2-methylpentane, perfluoro-1,2-dimethyl Hexane, perfluoro-1,3-dimethylhexane, 1H-perfluorohexane, 1H, 1H, 1H, 2H, 2H-perfluorohexane, 1H, 1H, 1H, 2H, 2H-perfluorooctane, 1H-perfluoro Octane, 1H-perfluorodecane, 1H, 1H, 1H, 2H, 2H-perfluorodecane Fluorine-containing aliphatic hydrocarbons, perfluorodecalin, perfluorocyclohexane, perfluoro-1,3,5-trimethylcyclohexane and other fluorine-containing alicyclic hydrocarbons, perfluoro-2-butyltetrahydrofuran, fluorine-containing low Fluorine-containing ethers such as molecular weight polyether can be used alone or in combination. For example, the organic solvent used for the optical film material A is methyl isobutyl ketone, and the organic solvent used for the optical film material B is a mixture of fluorine-containing alcohol (C ₆ F ₁₃ C ₂ H ₄ OH) and perfluorobutylamine. Solvent (95: 5). These organic solvents do not necessarily need to be 100% pure, and may contain impurities such as isomers, unreacted materials, decomposed products, oxides, and moisture as long as they are 20% or less.

  Moreover, after the coating material for optical thin films is formed into a coating film by coating, it becomes an optical thin film having a refractive index lower than that of the diffusion plate by a curing reaction. As a coating method at this time, various known methods such as dipping coating, gravure coating, roll coating, blade coating, and die coating may be used.

  In the case of the dipping coating method, by adjusting the viscosity of the paint and the pulling speed of the diffusion plate 113, the film thickness and the film thickness distribution of the optical thin film 114 are optimized, and the surface unevenness shape of the diffusion plate 113 is formed on the optical thin film 114. However, for example, it is preferable that the viscosity of the paint is 10 to 20 cps and the lifting speed is 84 to 430 cm / min. The reason why the pulling speed is set to 430 cm / min or less is that if the pulling speed is increased faster than 430 cm / min, the film thickness becomes too thick to achieve a desired appropriate film thickness.

(Reflective screen)
A configuration example of a reflective screen according to the present invention is shown in FIG. The reflective screen 10 has a configuration in which an optical multilayer film 12 that is a reflective layer and the above-described optical functional diffuser plate 11 are provided in order on a support 13, and further the optical screen on the back side of the support 13. A black light absorption layer is provided on the multilayer film 12.

  The support 13 is transparent and may satisfy any desired optical properties such as a transparent film, a glass plate, an acrylic plate, a methacrylstyrene plate, a polycarbonate plate, and a lens. As optical characteristics, the material constituting the support 13 preferably has a refractive index of 1.3 to 1.7, a haze of 8% or less, and a transmittance of 80% or more. Further, the support 13 may have an antiglare function.

The transparent film is preferably a plastic film, and examples of the material forming the film include cellulose derivatives (eg, diacetylcellulose, triacetylcellulose (TAC), propionylcellulose, butyrylcellulose, acetylpropionylcellulose and nitrocellulose), polymethyl (Meth) acrylic resins such as methacrylates and copolymers of vinyl monomers such as methyl methacrylate and other alkyl (meth) acrylates, styrene, etc .; polycarbonate resins such as polycarbonate, diethylene glycol bisallyl carbonate (CR-39); (Brominated) bisphenol A type di (meth) acrylate homopolymer or copolymer, (brominated) bisphenol A mono (meth) acrylate Thermosetting (meth) acrylic resins such as polymers and copolymers of tan-modified monomers; polyesters, especially polyethylene terephthalate, polyethylene naphthalate and unsaturated polyesters; acrylonitrile-styrene copolymers, polyvinyl chloride, polyurethane, epoxy Resins are preferred. In addition, an aramid resin considering heat resistance can be used. In this case, the upper limit of the heating temperature is 200 ° C. or higher, and the temperature range is expected to be widened.
The plastic film can be obtained by a method such as stretching these resins, diluting them in a solvent, forming a film and drying them. The thickness is preferably thick from the viewpoint of rigidity, but is preferably thin from the haze side, and is usually about 25 to 500 μm.

  In addition, the surface of the plastic film may be coated with a coating material such as a hard coat, and the presence of this coating material in the lower layer of an optical multilayer film composed of an inorganic substance and an organic substance allows adhesion, hardness, Various physical properties such as chemical resistance, durability, and dyeability can also be improved.

  The optical multilayer film 12 has a configuration in which a high refractive index optical film 12H as a first optical film and a low refractive index optical film 12L as a second optical film are alternately stacked. In FIG. 2, the optical film 12H having a high refractive index is first provided on each of both surfaces of the support 13, followed by the optical film 12L having a low refractive index, and thereafter the optical film 12H and the optical film 12L are alternately provided. Finally, the optical film 12H is provided, which is a laminated film composed of 2n + 1 layers per side (number of double-sided layers 2 (2n + 1)) (n is an integer of 1 or more).

The optical film 12H is an optical film formed by a curing reaction after applying an optical film material A described later on the support 13 or the optical film 12L. The optical film 12H contains fine particles for adjusting the refractive index. The film thickness of the optical film 12H is 80 nm to 15 μm, more preferably 600 to 1000 nm. This is because if the thickness is greater than 15 μm, the haze component due to fine particles that cannot be dispersed increases and the function as an optical film cannot be obtained.
The refractive index of the optical film 12H is preferably 1.70 to 2.10. When the refractive index is higher than 2.10, the dispersibility of the fine particles is insufficient and the function as an optical film is impaired. On the other hand, if the refractive index is lower than 1.70, the reflection characteristics when the optical film 12L is laminated are not sufficient, and the characteristics as a screen are insufficient.

  The optical film 12L is an optical film having a refractive index of 1.30 to 1.69, which is formed by a curing reaction after applying an optical film material B described later on the optical film 12H. The refractive index of the optical film 12L is determined by the type of resin contained in the optical film material B, and in some cases, the type and amount of fine particles added. If the refractive index is higher than 1.69, a difference in refractive index from the optical film 12H cannot be secured, and the reflection characteristics when laminated on the optical film 12H are not sufficient, and the characteristics as a screen are insufficient. . Moreover, it is difficult to form a film having a refractive index lower than 1.3, and the refractive index 1.3 is the lower limit in production.

  The film thickness of the optical film 12L is 80 nm to 15 μm, more preferably 600 to 1000 nm.

  With the above configuration, the optical multilayer film 12 has high reflection characteristics with respect to light in the three wavelength bands of red, green, and blue, and at least transmits light in the visible wavelength region other than these wavelength regions. It has characteristics. In addition, by adjusting the refractive index and thickness of each of the optical films 12H and 12L, it is possible to shift and adjust the wavelength position of the three wavelength bands reflected as the optical multilayer film 12, thereby projecting from the projector. The optical multilayer film 12 can be made to correspond to the wavelength of the light to be transmitted.

  The number of layers of the optical films 12H and 12L constituting the optical multilayer film 12 is not particularly limited, and can be set to a desired number of layers. The optical multilayer film 12 is preferably composed of an odd number layer in which the outermost layer on the projector light incident side and the opposite side is the optical film 12H. By making the optical multilayer film 12 an odd-numbered layer, the function as a three-primary-color wavelength band filter is superior to the case of an even-numbered layer.

  The specific number of layers of the optical multilayer film 12 is preferably 3 to 7 odd layers. This is because when the number of layers is 2 or less, the function as a reflective layer is not sufficient. On the other hand, the reflectivity increases as the number of layers increases, but the increase rate of reflectivity decreases when the number of layers is 8 or more, and the effect of improving reflectivity cannot be obtained as the time required for forming the optical multilayer film 12 is increased. is there.

  The light absorption layer 14 is for absorbing the light transmitted through the optical multilayer film 12 and the support 13. For example, in FIG. 2, the light absorption layer 14 is on the back side of the support 13 (the surface opposite to the optical functional diffusion plate 11). The aspect which stuck the black resin film on the outermost layer surface of the optical multilayer film 12 is shown.

Alternatively, the light absorption layer 14 may be a layer obtained by application using a black paint.
Examples of the black paint include fine particles in which carbon black is deposited on the surface, such as carbon black fine particles and silica fine particles. These fine particles may be conductive.
As a method for producing carbon black fine particles, an oil furnace method, a channel method, a lamp method, a thermal method and the like are known.

  For the purpose of sinking the black color, the primary particle size and dispersibility of the fine particles are the major factors determining the black color as the coating film, and the jet blackness is improved as the primary particle size is smaller and the surface area is larger. In addition, carbon black with many surface functional groups has high affinity with vehicles having polar functional groups such as OH groups and carboxyl groups like alkyd resins. Improved, gloss and jetness increase. Moreover, it is good to add the hardening | curing agent which has the isocyanate group and carboxyl group which are reactive with the functional group which the said resin has, and to harden a coating film.

  Generally, the amount of surface functional groups is larger in channel carbon than in furnace carbon. However, the amount of functional groups can be increased by performing oxidation treatment even in the furnace method. The primary particle diameter of carbon black is preferably 30 nm or less, and more preferably 20 nm or less. As the particle size increases, the jetness decreases and the performance as a light absorbing layer decreases.

  The coating method may be a conventionally known method such as screen coating, blade coating or spray coating.

  Moreover, about 10-50 micrometers is preferable and, as for a film thickness, More preferably, it is 15-25 micrometers. When the film thickness is smaller than 10 μm, the jetness is lowered particularly in the case of spray coating. On the other hand, when the film thickness is larger than 50 μm, the coating film becomes brittle and cracks are likely to occur.

  The screen 10 can selectively reflect the surface of the screen by suppressing the surface scattering of light, reflecting light of a specific wavelength from the projector, and transmitting / absorbing light of other wavelengths such as external light. Thus, a high contrast is achieved by lowering the black level of the image on the screen 10, and an image with a high contrast can be displayed even in a bright room. For example, when light from an RGB light source such as a diffraction grating projector using a grating light valve (GLV) is projected, the screen 10 has a wide viewing angle, high contrast, and reflection of external light. There will be no good video.

  That is, the light incident on the screen 10 passes through the optical functional diffuser plate 11 without being scattered on the surface, reaches the optical multilayer film 12, and the external light component included in the incident light is transmitted through the optical multilayer film 12. Then, the light is absorbed by the light absorption layer 14 and only light in a specific wavelength region related to the image is selectively reflected, and the reflected light is diffused on the surface of the optical functional diffuser plate 11 as image light having a wide viewing angle. To be served. Therefore, the influence of external light on the image light that is the reflected light can be eliminated at a high level, and an unprecedented high contrast can be achieved.

  As the screen according to the present invention, an optical multilayer film having the same structure as described above is formed on the front surface of the support, and an optical functional diffusion plate is formed on the outermost surface of the optical multilayer film. It is good also as a structure by which the light absorption layer was formed in the back surface. Even with this screen, it is possible to reduce the black level on the screen and achieve high contrast by reflecting light of a specific wavelength from the projector and transmitting and absorbing incident light in other wavelength regions such as outside light. It is.

  Here, the optical film materials A and B, which are paints for forming the first optical film and the second optical film, will be described.

(1) Optical film material A
The optical film material A contains fine particles, an organic solvent, a binder that absorbs energy to cause a curing reaction, and a dispersant.

  Fine particles are fine particles of a high refractive index material added to adjust the refractive index of the optical film after film formation, such as Ti, Zr, Al, Ce, Sn, La, In, Y, Sb, etc. Or alloy oxides such as In-Sn. In addition, even if an appropriate amount of oxide such as Al or Zr is contained in the Ti oxide for the purpose of suppressing the photocatalyst, the effect of the present invention is not hindered.

The specific surface area of the fine particles is preferably from 55 to 85 m ² / g, it is more preferably 75~85 m ² / g. When the specific surface area is in this range, it is possible to suppress the particle size of the fine particles in the optical film material to 100 nm or less by the dispersion treatment of the fine particles, and an optical film having a very small haze can be obtained.

  Organic solvents include, for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, alcohol solvents such as methanol, ethanol, propanol, butanol, isobutyl alcohol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate An ester solvent such as ethylene glycol acetate is used. These organic solvents do not necessarily need to be 100% pure, and may contain impurities such as isomers, unreacted products, decomposed products, oxides, and moisture if they are 20% or less. Further, in order to apply on a support or optical film having a low surface energy, it is desirable to select a solvent having a lower surface tension, and examples thereof include methyl isobutyl ketone, methanol, ethanol and the like.

  Examples of the binder that undergoes a curing reaction with the dispersant include a thermosetting resin, an ultraviolet (UV) curable resin, and an electron beam (EB) curable resin. Examples of thermosetting resin, UV curable resin, EB curable resin are polystyrene resin, styrene copolymer, polycarbonate, phenol resin, epoxy resin, polyester resin, polyurethane resin, urea resin, melamine resin, polyamine resin, urea Examples include formaldehyde resin. Polymers having other cyclic (aromatic, heterocyclic, alicyclic, etc.) groups may also be used. Further, a resin containing fluorine or silanol group in the carbon chain may be used.

  The method for curing the resin may be either radiation or heat. However, when the resin curing reaction is performed by ultraviolet irradiation, it is preferably performed in the presence of a polymerization initiator. Examples of radical polymerization initiators include azo initiators such as 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile); benzoyl peroxide, lauryl peroxide And peroxide initiators such as t-butyl peroctoate. The amount of these initiators used is 0.2 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the total polymerizable monomers.

The content of the dispersant for dispersing the fine particles is 3.2 to 9.6 × 10 ¹¹ mol / m ² with respect to the fine particles, but if the content is less than this, sufficient dispersibility cannot be obtained in the optical film. On the other hand, if the content is large, the volume ratio of the dispersant in the coating film increases, so that the film refractive index decreases and the refractive index adjustment range becomes narrow, making it difficult to design an optical film stack.

The amount of the polar functional group of the hydrophilic group contained in the dispersant is 10 ⁻³ to 10 ⁻¹ mol / g. When the functional group is smaller or larger than this, the effect on the dispersion of the fine particles is not exhibited, leading to a decrease in dispersibility.

As the polar functional group, the following functional groups are useful because they are not in an aggregated state.
-SO ₃ M, -OSO ₃ M, -COOM, P = O (OM) ₂ (where M is a hydrogen atom or an alkali metal such as lithium, potassium, sodium, etc.), tertiary Amine, quaternary ammonium salt R1 (R2) (R3) NHX (wherein R ₁ , R ₂ , R ₃ are hydrogen atoms or hydrocarbon groups, X ⁻ is chlorine, bromine, iodine, etc.) Halogen element ion or inorganic / organic ion.)
-There are no particular restrictions on the introduction site of polar functional groups such as -OH, -SH, -CN, and epoxy groups. These dispersants can be used alone or in combination of two or more.

  The total amount of the dispersant of the present invention in the coating film is preferably 20 to 60 parts by weight, more preferably 38 to 55 parts by weight with respect to 100 parts by weight of the ferromagnetic powder.

  Further, the weight average molecular weight of the dispersant lipophilic group is preferably 110 to 3000. When the molecular weight is lower than this range, there are problems such as insufficient dissolution in organic solvents. Conversely, when it is too high, sufficient dispersibility cannot be obtained in the optical film. The molecular weight of the dispersant may be measured by a gel permeation chromatograph (GPC) method.

  The dispersant may have a functional group for causing a curing reaction with the binder. In addition, when a binder other than the dispersant of the present invention is included, a polyfunctional polymer or monomer having many linking groups is preferable.

  After the optical film material A is formed into a coating film by coating, the curing reaction is promoted by radiation or heat to become a high refractive index type first optical film.

(2) Optical film material B
The optical film material B may be the same as the coating material for the optical thin film. The optical film material B is formed into a coating film by coating, and then has a lower refractive index than the first optical film by a curing reaction. 2 optical film.

  The optical film materials A and B are produced by a kneading step, a dispersing step, and a mixing step provided as necessary before and after these steps. All raw materials such as fine particles, resin, and solvent used in the present invention may be added at the beginning or during any step. In addition, individual raw materials may be added in two or more steps. For dispersion and kneading, a conventionally known apparatus such as an agitator or a paint shaker may be used.

(Reflective screen manufacturing method)
A method for manufacturing the reflective screen 10 according to the present invention will be described below.
(S1) A polyethylene terephthalate (PET) film is prepared as the support 13, and the support 13 is immersed in a tank filled with the optical film material A, and a predetermined amount of optical material is applied to both sides of the support 13 by a dipping method. Film material A is applied.
(S2) The coating film of the optical film material A is dried to form the optical film 12H having a predetermined thickness.
(S3) Next, a predetermined amount of optical material is applied onto the optical film 12H on both surfaces of the support 13 by dipping in which the support 13 on which the optical film 12H is formed is dipped in a tank filled with the optical film material B and pulled up. The film material B is applied.
(S4) The coating film of the optical film material B is dried to form an optical film 12L having a predetermined thickness. Thereby, it becomes a laminated structure of the optical film 12H and the optical film 12L.
(S5) Next, the support 13 in which the optical films 12H and 12L are laminated is dipped in a tank filled with the optical film material A and pulled up to be placed on the optical film 12L on the outermost layer on both sides of the support 13 A predetermined amount of the optical film material A is applied.
(S6) After drying the coating film of the optical film material A, the optical film material A is cured by irradiating with ultraviolet rays to form an optical film 12H having a predetermined film thickness. Thereafter, the processes from steps s3 to s6 are performed a predetermined number of times, and the optical multilayer film 12 is formed on both surfaces of the support 13.

(S7) The optical functional diffusion plate 11 is attached to the front surface of the optical multilayer film 12 via an adhesive layer.

(S8) A resin containing a black light absorber is applied to the back surface of the optical multilayer film 12 on the back surface side of the support 13 to form the light absorption layer 14, thereby obtaining the reflective screen 10 according to the present invention.

  In addition, although the case where the optical film materials A and B are applied by the dipping method is shown here, the optical film materials A and B are applied by a conventionally known application method such as gravure coating, roll coating, blade coating, and die coating. Each of B may be applied.

  As another embodiment of the screen according to the present invention, an optical multilayer film 12 having the same configuration as described above is formed on the front surface of the support 13, and optical functionality is provided on the outermost layer surface of the optical multilayer film 12. The diffusion plate 11 may be formed, and the light absorption layer 14 may be formed on the back surface of the support 13. Even with this screen, it is possible to reduce the black level on the screen and achieve high contrast by reflecting light of a specific wavelength from the projector and transmitting and absorbing incident light in other wavelength regions such as outside light. It is.

  An example in which the present invention is actually implemented will be described below. This example is illustrative, and the present invention is not limited to this example.

(Example 1)
The diffusion plate in Example 1, the composition of the coating for optical thin film, the method for producing the optical functional diffusion plate, and the following are shown.
(1) Diffusion plate The diffusion plate was prepared by providing an epoxy resin on a PET substrate and copying it to the epoxy resin layer using a master mold having a surface structure prepared in advance.
・ Unevenness level difference: 3 to 10 μm
・ Viewing angle: 60 ° in the horizontal direction, 10 ° in the vertical direction
(2) Coating for optical thin film / polymer of perfluorobutenyl vinyl ether having terminal carboxyl group (product name: Cytop, manufactured by Asahi Glass Co., Ltd.)
(3) Manufacturing method of optical functional diffusion plate The optical thin film coating material was applied on the diffusion plate by a dipping method and dried at 90 ° C. to obtain an optical functional diffusion plate. In addition, as a coating condition, the viscosity of the coating material for optical thin films was fixed to 10 cps, and the lifting speed of the diffusion plate was set to 170 mm / min.
In addition, about the obtained optical functional diffusion plate, the film thickness of each optical thin film of the convex part of a diffusion plate surface, an intermediate | middle area | region (intermediate), and a recessed part was measured by cross-sectional TEM.

Next, the composition, production method and screen production method of the coating material (I) which is the optical film material A and the coating material (II) which is the optical film material B are shown below.
(3) Optical film material A (paint (I))
Fine particles: TiO ₂ fine particles (Ishihara Sangyo Co., Ltd., average particle diameter of about 20 nm, refractive index 2.48) 100 parts by weight Dispersant: SO ₃ Na group-containing molecule (weight average molecular weight: 1000, SO ₃ Na group concentration: 2 × 10 ⁻³ mol / g)
20 parts by weight-Binder: Mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (Nippon Kayaku UV curable resin, trade name DPHA) 30 parts by weight-Organic solvent: methyl isobutyl ketone (MIBK) 4800 Part by weight First, a predetermined amount of fine particles, a dispersant, and an organic solvent were mixed and dispersed with a paint shaker to obtain a TiO ₂ fine particle dispersion. Next, a binder was added to the dispersion, and the mixture was stirred with a stirrer to obtain paint (I).
(4) Optical film material B (paint (II))
・ Polyfluorobutenyl vinyl ether polymer with terminal carboxyl group (product name: Cytop, manufactured by Asahi Glass Co., Ltd.)

(5) Screen manufacturing method (s11) The paint (I) is applied to both surfaces of the transparent support by a dipping method.
(S12) The coating film of paint (I) is dried at 80 ° C. and then cured by ultraviolet (UV) (1000 mJ / cm ² ) to form an optical film (I) having a film thickness of 780 nm per side and a refractive index of 1.94. .
(S13) Next, the coating material (II) is applied by dipping on the high refractive index optical film.
(S14) The coating film of paint (II) is dried at 90 ° C. to form an optical film (II) having a thickness of 1240 nm and a refractive index of 1.34.
(S15) The paint (I) is applied on the optical film (II) under the same conditions as in step s11.
(S16) A coating film of paint (I) is formed under the same conditions as in step s12 to form an optical film (I) having a film thickness of 780 nm per side and a refractive index of 1.94. As a result, a total of six optical multilayer films (three layers of optical film (I) / optical film (II) / optical film (I) per side) were obtained on the transparent support.
(S17) The optical functional diffusion plate is bonded to one surface of the optical multilayer film through an adhesive layer.
(S18) A black paint shown below is applied to the other surface of the optical multilayer film by a spray method, dried and cured to form a black light absorbing layer, and a reflective screen is obtained.
[Black paint]
Black fine particles: Dispersion in which carbon black of 2 to 3 nm is coated on silica fine particles having an average particle diameter of 15 nm Solvent: Propyl glycol methyl acetate (PGMA)

  In the evaluation of the formed optical multilayer film, the refractive indexes of the optical film (I) and the optical film (II) were measured by Philmetrics (manufactured by Matsushita Intertechno Co., Ltd.). Further, the haze of the optical multilayer film was measured with a haze meter (JASCO V-560 type). Further, the reflection characteristics of the obtained optical multilayer film were measured by Filmetrics (manufactured by Matsushita Intertechno Co., Ltd.). As the reflection characteristics, the respective reflectances in the three primary color wavelength regions of a blue region having a wavelength of 465 nm, a green region having a wavelength of 545 nm, and a red region having a wavelength of 665 nm were measured.

Further, in evaluating the obtained reflective screen, the gain of the screen was measured with a spectral radiance meter (CS-1000, manufactured by Minolta). The gain is the maximum value of the ratio when the luminance (cd / m ² ) of the white plate when the white plate is irradiated with light is 1.
Further, the luminance of this screen was measured with the above luminance meter, and the contrast was determined. That is, measure the brightness when the screen is irradiated with white light from the projector, then measure the brightness when the black light is irradiated from the projector, and from the ratio of the brightness when this white and black light is irradiated Contrast was measured.

(Examples 2 and 3)
In the manufacturing process of the optical functional diffuser, the film thickness of the optical thin film is changed by setting the dipping pulling speeds at the time of forming the optical thin film to 260 and 430 mm / min, respectively. A mold screen was obtained.

(Examples 4 and 5)
In the manufacturing process of the optical functional diffusion plate, the viscosity of the optical thin film coating was changed to 15 and 20 cps, respectively, and the film thickness of the optical thin film was changed. .

(Example 6)
In the manufacturing process of the optical functional diffusion plate, the refractive index of the optical thin film is changed as a fluorine-based resin having a trade name of LC930, manufactured by Daikin Co., Ltd. A mold screen was obtained.

(Example 7)
In the optical functional diffusion plate manufacturing process, the optical thin film paint is mixed with 100 parts by weight of silica fine particles (catalyst chemicals, trade name OSCAL) and 14 parts by weight of fluororesin (trade name GK500, trade name: Daikin). The reflection type screen was obtained under the same conditions as in Example 1 except that the paint was obtained.

(Example 8)
In the production process of the reflective screen, the number of repetitions of the optical film forming step is increased, the number of laminated optical multilayer films is 7 layers on one side of the support, a total of 14 layers, and other conditions are the same as the conditions in Example 1. A reflective screen was obtained.

Example 9
In the manufacturing process of the optical functional diffuser, the viewing angle of the diffuser was set to 10 ° in the horizontal direction and 10 ° in the vertical direction, and the other conditions were the same as those in Example 1, and a reflective screen was obtained.

(Example 10)
In the manufacturing process of the optical functional diffuser, the viewing angle of the diffuser was set to 20 ° in the horizontal direction and 20 ° in the vertical direction, and the other conditions were the same as those in Example 1, and a reflective screen was obtained.

(Example 11)
In the manufacturing process of the optical functional diffuser, the viewing angle of the diffuser was set to 30 ° in the horizontal direction and 30 ° in the vertical direction, and the other conditions were the same as those in Example 1, and a reflective screen was obtained.

(Example 12)
In the manufacturing process of the optical functional diffuser plate, the dipping pulling speed at the time of forming the optical thin film is set to 84 mm / min, and the film thickness of the optical thin film is changed. Obtained.

(Examples 13 to 24)
Instead of the black light-absorbing layers of Examples 1 to 12, the following black paint is applied to the back side of the PET film (one outermost layer surface of the optical multilayer film) by spray coating, and 75 as a drying and curing process. A screen was obtained by keeping the temperature for 30 minutes at 30 ° C., forming a black light absorbing layer, and other conditions being the same as those of Examples 1-12.
[Black paint] A composition obtained by adding a solvent to the following composition was used.
・ Carbon black fine particle: Origin Electric Co., Ltd.
(Primary particle size: 15 nm)
Resin: Alkyd resin having a hydroxyl group In addition, as a curing agent, product name Polyhard MH (isocyanate type) manufactured by Origin Electric Co., Ltd. was used.

(Comparative Examples 1 and 2)
In the manufacturing process of the optical functional diffuser plate, the film thickness of the optical thin film is changed by setting the dipping pulling speed at the time of forming the optical thin film to 30 and 50 mm / min, respectively. A mold screen was obtained.

(Comparative Example 3)
In the manufacturing process of the optical functional diffuser, the refractive index of the optical thin film is changed as an acrylic resin of the trade name DPHA made by Nippon Kayaku Co., Ltd., and the other conditions are the same as those in Example 1 A reflective screen was obtained.

(Comparative Example 4)
In the manufacturing process of the optical functional diffuser, the dipping pulling speed at the time of forming the optical thin film is changed to 75 mm / min to change the film thickness of the optical thin film. Obtained.

The results of Examples 1-12 are shown in Table 1, the results of Examples 13-24 are shown in Table 2, and the results of Comparative Examples are shown in Table 3.
In any of the examples, a reflection screen with high gain and high contrast was obtained. On the other hand, the improvement effect was not recognized in any of Comparative Examples 1-4. The gain is obtained by changing the black fine particles contained in the black light absorbing layer from fine particles (Examples 1 to 12) obtained by depositing carbon black on the surface of silica fine particles to pure carbon black fine particles (Examples 13 to 24). In addition, the contrast was improved.

It is sectional drawing which shows the structure of embodiment of the optical functional diffuser plate which concerns on this invention. It is sectional drawing which shows the structure of embodiment of the reflection type screen which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Reflective type screen, 11 ... Optical functional diffuser plate, 12 ... Optical multilayer film, 12H, 12L ...
Optical film, 13 ... support, 14 ... black light absorbing layer, 111 ... base sheet, 112 ... bead layer,
113 ... diffusion plate, 114 ... optical thin film

Claims (14)

A diffusion plate having irregularities on the surface, and an optical thin film having a refractive index lower than that of the diffusion plate on the diffusion plate surface,
The optical thin film is characterized in that the optical thin film is formed so as to reflect the uneven shape on the surface, and is provided so that the film thickness gradually increases from a convex part to a concave part on the surface of the diffusion plate. Board.   2. The optical functional diffusion plate according to claim 1, wherein the unevenness difference of the diffusion plate is 1 μm or more and 30 μm or less.   2. The optical functional diffusion plate according to claim 1, wherein the thickness of the optical thin film is 70 nm or more and 110 nm or less at the convex portion, and is 100 nm or more at the concave portion and not more than the unevenness difference of the diffusion plate.   2. The optical functional diffuser plate according to claim 1, wherein the optical thin film is formed from a paint containing a fluorine resin. _2. The optical functional diffusion plate according to claim 1, wherein the optical thin film is formed from a paint containing SiO2 fine particles.   A reflective screen comprising a reflective layer and the optical functional diffusion plate according to any one of claims 1 to 5 in order on a support.   The reflective layer is composed of 2n + 1 (n is an integer of 1 or more) layers in which a first optical film having a high refractive index and a second optical film having a lower refractive index are alternately stacked. The optical multilayer film having high reflection characteristics with respect to light in a specific wavelength region and high transmission characteristics at least in a visible wavelength region other than the specific wavelength region. Reflective screen.   The reflective screen according to claim 7, wherein the support is transparent, and the optical multilayer film is formed on both sides of the support.   The reflective screen according to claim 7, wherein the optical multilayer film has a laminated structure in which an outermost layer is formed of a first optical film.   The reflective screen according to claim 7, wherein the specific wavelength region includes red, green, and blue wavelength regions. The first optical film is a film obtained by applying a paint containing metal oxide fine particles, a dispersant, and a binder, and the second optical film is a paint containing a fluororesin or SiO ₂ fine particles. The reflective screen according to claim 7, wherein the reflective screen is a film obtained by coating the film.   The reflective screen according to claim 11, wherein the fluororesin has a functional group that absorbs energy to cause a curing reaction.   The reflective screen according to claim 7, further comprising a black light absorption layer on a back side of the support. A method for producing a reflective screen, wherein a reflective layer and the optical functional diffuser plate according to any one of claims 1 to 5 are sequentially provided on a support,
A method for producing a reflective screen, comprising the step of forming an optical thin film on the surface of the diffusion plate by dipping as the production step of the optical functional diffusion plate.

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