JP2005115243A - Reflection type screen and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection type screen on which an image with high luminance and high contrast is obtained, and to provide its manufacturing method. <P>SOLUTION: On a base 11, a 1st optical film having a high refractive index and a 2nd optical film having a lower refractive index than it are laminated by turns to form an optical multi-layered film 12 which comprises 2n+1 (n: an integer of ≥1) layers and has a high reflection characteristic to light in a specified wavelength range and a high transmission characteristic to light at least in the visible wavelength range other than the specified wavelength range; and a plurality of transparent spheres 141 are arrayed in one layer on the optical multi-layered film 12 across an adhesion layer 13, and the transparent spheres 14 are partially exposed in the adhesion layer 13 and fixed to form a bead layer 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reflective screen capable of viewing an image with high brightness and high contrast under bright light and a method for manufacturing the same.

  In recent years, overhead projectors and data projectors have been widely used as methods for presenting materials by a speaker in a conference or the like. In general households, video projectors and moving picture film projectors using liquid crystals are becoming popular due to their small size, light weight, and low price.

  In these projector projection methods, light output from a light source is modulated by a light valve to form image light, and the image light is emitted through an optical system such as a lens and projected onto a reflective screen. .

  Some projectors of this type can display a color image. As a light source, white light including the three primary colors red (Red = R), green (Green = G), and blue (Blue = B) is used. A light emitting lamp is used, and a transmissive liquid crystal panel is mainly used as a light valve. In this projector, white light emitted from the light source is separated into light beams of each color of red light, green light, and blue light by the illumination optical system, and these light beams are converged on a predetermined optical path. These light beams are spatially modulated by the liquid crystal panel in accordance with the image signal, the modulated light beams are combined as color image light by the light combining unit, and the combined color image light is enlarged and projected onto the screen by the projection lens.

  Some of the reflective screens used in such projectors reflect image light emitted from a projector (front projector) in front of the screen so that the projected image can be viewed with the reflected light. In order to obtain visibility, it is required to display an image with high brightness and high contrast.

  Conventionally, a white screen with an embossed surface has been used as the reflective screen, but the contrast and brightness of the reflected image light are insufficient. Further, as shown in FIG. 14, the projector light incident on the center of the screen is reflected and returns in the direction in which the projector is positioned, but the projector light incident on the corner of the screen is reflected and reflected. Most will return to the outside of the screen. Therefore, as shown in FIG. 15, an observer near the projector position sees an image having a luminance distribution that is bright at the center of the screen and dark at the corner.

  Therefore, in recent years, a reflective screen having a configuration in which transparent beads with light focusing properties are uniformly arranged on a reflective layer on a substrate has been disclosed (for example, see Patent Document 1). Thereby, the brightness | luminance of the image light reflected improved from the conventional one.

  However, in such a reflective screen, although the brightness is improved, an image with a low contrast is produced due to the influence of room disturbance light (fluorescent light, sunlight), so that an appropriate contrast image is obtained. Needed to darken the room.

  For the above problem, the selective reflection layer that selectively reflects light according to the wavelength region is used to mainly reflect the image light projected from the projector, and light from other than the projector such as a fluorescent lamp or the sun That is, a screen that does not reflect external light has been proposed (see, for example, Patent Document 2). In this screen, a selective reflection layer is formed on a support, a diffusion layer that scatters reflected light is provided on the front surface of the selective reflection layer, and an absorption layer that absorbs transmitted light is provided behind the selective reflection layer. The selective reflection layer is an optical multilayer film in which a high refractive index optical film and a low refractive index optical film are alternately stacked, and the wavelength region of projector light, for example, red (R), green (G), Blue (B) has a characteristic of reflecting light in the three primary color wavelength regions and transmitting light in wavelength regions other than the three primary color wavelength regions. In this screen, the influence of outside light can be greatly reduced, so even in a bright room, the black level can be lowered without lowering the screen gain, and a clear image with high contrast can be displayed. It has become.

JP-A-3-53232 JP 2003-270725 A

  However, since the wavelength characteristics of the light of a projector using a high-pressure mercury lamp or the like as light source and outside light, in particular, fluorescent light are very similar, only the projector light can be obtained by the optical multilayer film. It was difficult to selectively reflect.

  In addition, since the high refractive index layer and the low refractive index layer are assumed to be formed by a dry process such as a sputtering method, the size of the processing chamber to be evacuated in the film forming apparatus is restricted and the processing chamber The size of the support that can be inserted into the screen is also limited, and it has been difficult to enlarge the screen. In addition, there is a limit to mass production due to the dry process.

In addition, a diffuser plate or a light shielding plate using the angles of incidence on the screens of the projector light and external light has been proposed, but the screen structure becomes complicated, or moire occurs due to the periodic screen structure. There was a problem such as that.
In addition, an ordinary screen requires so-called gain control that effectively directs light reflected from the screen toward the viewer, but its structure is complicated and difficult to make.

  The present invention has been made in view of the above problems in the prior art, and an object of the present invention is to provide a reflective screen capable of obtaining a high-brightness and high-contrast image and a method for manufacturing the same.

  The inventor has paid attention to the retroreflection characteristics of the transparent beads and the selective reflection characteristics of the optical multilayer film, and as a result of intensive studies, has solved the above problems and has achieved the present invention.

  In other words, a reflective screen according to the invention of claim 1 provided to solve the above-mentioned problems is provided on a support with a first optical film having a high refractive index and a second optical film having a lower refractive index. And 2n + 1 (n is an integer greater than or equal to 1) layers, having high reflection characteristics with respect to light in a specific wavelength region, and at least a visible wavelength region other than the specific wavelength region An optical multilayer film having a high transmission characteristic is formed, and a plurality of transparent spheres are arranged on the optical multilayer film through an adhesive layer, and a part of the transparent sphere is exposed from the adhesive layer, A bead layer is formed by being fixed.

  The reflection type screen according to the invention of claim 2 provided to solve the above-mentioned problems is the reflection screen according to the invention of claim 1, wherein the support is transparent and the optical multilayer film is formed on both surfaces of the support. It is characterized by that.

  The reflective screen according to the invention of claim 3 provided to solve the above-mentioned problem is the reflection type screen according to the invention of claim 1, wherein the adhesive layer is formed by laminating a transparent layer and a black layer in order from the optical multilayer film side. It is characterized by a layer structure.

  According to a fourth aspect of the present invention, there is provided a reflective screen according to the fourth aspect of the present invention, wherein the optical multilayer film has a laminated structure in which the outermost layer is formed of the first optical film. It is characterized by that.

According to a fifth aspect of the present invention, there is provided a reflective screen according to the fifth aspect, wherein the first optical film includes metal oxide fine particles, a dispersant, and a binder. It is a film obtained by applying a material, and the second optical film is a film obtained by applying a material containing fluorine-containing resin or SiO ₂ fine particles.

  The reflective screen according to the invention of claim 6 provided to solve the above-mentioned problems is characterized in that, in the invention of claim 1, the specific wavelength region includes each of red, green, and blue wavelength regions. To do.

  The reflective screen according to the invention of claim 7 provided to solve the above-mentioned problems is characterized in that, in the invention of claim 1, a black light absorbing layer is provided on the back side of the support.

  The method for manufacturing a reflective screen according to the invention of claim 8 provided to solve the above-mentioned problems has a high reflection characteristic with respect to light in a specific wavelength region on a support, and the specific wavelength region. 2n + 1 (n is an integer greater than or equal to 1) layer having high transmission characteristics in at least the visible wavelength region, and a plurality of transparent spheres are arranged in one layer on the optical multilayer film A reflective screen manufacturing method comprising a bead layer in which a part of the transparent sphere is exposed and fixed via an adhesive layer, wherein the manufacturing process of the optical multilayer film has a high refractive index first. A first coating step of forming the second optical film by coating, and a second coating step of forming a second optical film having a refractive index lower than that of the first optical film by coating. And the second coating step are alternately performed.

  According to a ninth aspect of the present invention, there is provided a reflective screen manufacturing method according to the ninth aspect of the present invention, wherein the bead layer manufacturing step comprises a coating liquid containing a resin on the optical multilayer film. Forming a coating film by coating, a step of arranging a plurality of transparent spheres in the coating film in one layer, and embedding so that a part of the transparent sphere is exposed from the coating film surface; And a step of curing the film to form an adhesive layer.

  In order to solve the above-mentioned problems, a reflective screen manufacturing method according to the invention of claim 10 is the invention of claim 9, wherein the coating film comprises a transparent coating film and a black coating film from the optical multilayer film side. It is applied in order, and has a two-layer structure in which a transparent layer and a black layer are laminated by curing.

  According to the first aspect of the present invention, since the light reflected by the screen returns to the exit direction of the projector due to the retroreflective property of the transparent sphere (bead), high brightness can be obtained by viewing from the same direction as the projector. You can see the image. In addition, since the light hitting the center or corner of the screen returns to the viewer's direction (projection direction of the projector), the luminance ratio between the center and the corner is difficult to be applied, and a more uniform image can be enjoyed.

  Also, due to the recursive characteristics of the transparent sphere, the disturbance light is recursed in the direction in which the disturbance light has come, so the influence of the disturbance light on the image on the screen is greatly reduced, resulting in a high-contrast image. Furthermore, since the light transmitted through the transparent sphere is selectively reflected by the optical multilayer film, an image with higher contrast is obtained. Accordingly, it is possible to enjoy high brightness and high contrast images even in a bright environment.

  Further, since the dispersed transparent sphere itself also serves as an imaging layer, the diffusion plate that has been conventionally provided as the imaging layer can be omitted. As a result, it is possible to reduce surface reflection that occurs when the diffusion plate is used, and to reduce light loss in the diffusion plate or its adhesive layer.

  According to the second aspect of the invention, even if the number of laminated layers per side is the same, the number of laminated layers is twice that of a conventional screen in which an optical multilayer film is provided only on one side, so that a high reflectance can be obtained. Is possible. Further, if the optical multilayer film is formed by coating, the screen can be easily enlarged and the cost can be reduced.

  According to the third aspect of the present invention, it becomes possible to absorb the disturbance light incident by the black layer provided on the adhesive layer, and to further reduce the influence of the disturbance light, a higher contrast image can be obtained. . Further, by controlling the thickness of the black layer, the angle dependency of the ambient light to be absorbed can be controlled.

  According to the fourth and fifth aspects of the invention, the outermost layer on the projector light incident side and on the opposite side has an odd-numbered layer structure serving as a first optical film having a high refractive index, and has an excellent function as a selective reflection layer. It becomes. Moreover, since the optical film thickness of each of the first optical film and the second optical film can be arbitrarily set, it has a characteristic of reflecting light in a desired wavelength region and transmitting light in a wavelength region other than the wavelength region. An optical multilayer film can be formed, and a screen with high brightness, high contrast, and high reflectance corresponding to the projector light source can be realized.

  According to the sixth aspect of the present invention, it is possible to obtain a screen on which a good image with high contrast with respect to the RGB light source can be viewed.

  According to the seventh aspect of the present invention, since the light transmitted through the optical multilayer film is absorbed, a good image with higher contrast can be viewed.

  According to the invention described in claims 8 to 10, since the optical multilayer film can be more easily formed on a support having a larger size than in the case of the dry process, mass production of a large screen with high brightness and high contrast is possible. Become.

The first embodiment of the reflective screen according to the present invention will be described below.
FIG. 1 is a cross-sectional view showing the configuration of a reflective screen according to the present invention.
As shown in FIG. 1, the screen 10 is provided with an optical multilayer film 12 on both surfaces of a support 11, and a bead layer 14 is provided on the optical multilayer film 12 on the front surface side via an adhesive layer 13, The black light absorption layer 15 is provided on the optical multilayer film 12 on the back side.

  The support 11 is transparent and may satisfy any desired optical characteristics 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 11 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 11 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.

  Further, an undercoat layer may be provided on the support 11 as an optical functional thin film or a transparent support surface treatment. Examples of the undercoat layer include organoalkoxy metal compounds, polyesters, acrylic-modified polyesters, and polyurethanes. Moreover, it is preferable to perform corona discharge and UV irradiation treatment.

  The optical multilayer film 12 forms the basis of the present invention, and 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 laminated. It is a configuration. Specifically, from the support 11, an optical film 12H having a high refractive index is first provided, then an optical film 12L having a low refractive index is provided, and thereafter the optical film 12H and the optical film 12L are provided alternately. The optical film 12H is provided, and is a laminated film composed of 2n + 1 layers (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 11 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. It should be noted that by adjusting the refractive index and thickness of each of the optical films 12H and 13L, 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 13L 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.

  In the bead layer 14, as shown in FIG. 2, a plurality of transparent spheres 141 are arranged in one layer on the surface of the optical multilayer film 12 via a transparent adhesive layer 13, and a part of the transparent sphere 141 is exposed from the adhesive layer 13. It is a fixed layer. Here, the transparent spheres 141 are arranged so as to cover the surface of the optical multilayer film 12, but the arrangement may be random, and there may be a gap in the horizontal direction with respect to the surface of the optical multilayer film 12. Further, it is most preferable that the transparent sphere 141 has an area of about ½ of its diameter exposed from the adhesive layer 13.

FIG. 3 schematically shows the retroreflection characteristics of the bead layer 14.
The light incident on the transparent sphere 141 is narrowed by the lens effect of the transparent sphere 141, is reflected by the optical multilayer film 12 below the bead layer 14, and the reflected light returns in the incident direction (retroreflective characteristics). ). Therefore, as shown in FIG. 4, since the reflected light at the center and corner of the screen returns to the direction in which the projector is located, the observer near the projector position has a difference in brightness between the center and corner of the screen. You can see images with little.

  The transparent sphere 141 is a transparent sphere that transmits light as much as possible, and its refractive index is preferably 1.4 or more. When the refractive index of the transparent sphere 141 changes, the lens effect of the transparent sphere 141 changes, and the light condensing property and the focal length change. In the present invention, by setting the refractive index to 1.4 or more, the light incident on the transparent sphere 141 is sufficiently condensed and the lens effect is effectively utilized. Regarding the focal length, the light use efficiency can be achieved by designing the diameter of the transparent sphere 141 and the distance between the transparent sphere 141 and the optical multilayer film 12 so that the position of the reflective surface (the surface of the optical multilayer film 12) is as focal as possible. Will improve. The transparent sphere 141 may be glass beads, for example.

  Further, the smaller the diameter of the transparent sphere 141, the smaller the gap between the transparent spheres 141 when the transparent spheres 141 are densely arranged, so that the light utilization efficiency is improved, the high-resolution image expression power is excellent, and the transparent sphere 141 is transparent. There is an advantage that a moire pattern hardly occurs even when some periodicity occurs in the arrangement of the spheres 141, which is preferable.

  It is generally known that when there are two or more periodic patterns, the patterns interfere with each other and moire occurs. In the combination of the projector and the reflective screen, the pixel pattern and the screen pattern interfere with each other, and moire occurs. As this moire reduction method, it is known that the pitch difference between the two should be 4.5 times or more (Japanese Patent Laid-Open No. 3-168630).

Here, for example, when a full HD (1920 × 920) image is projected onto an 80 inch screen with a 9:16 aspect ratio, the pixel pitch is 922 μm. Considering the case of using beads having a diameter of 200 μm, the pitch difference is 922/200 = 4.61 (≈4.5), and when the diameter exceeds 200 μm, a moire problem newly arises.
Therefore, in the present invention, in consideration of other factors (filling rate, light utilization efficiency, etc.), the transparent sphere 141 preferably has a diameter of 100 μm or less.

  The adhesive layer 13 is a transparent resin layer for fixing the transparent sphere 141 on the optical multilayer film 12. Although the adhesive is formed by curing, any transparent adhesive such as a hot melt type, an ultraviolet curing type, or a thermosetting type may be used, and it may be appropriately selected according to the method of forming the bead layer 14. . Further, if necessary, a diffusing agent may be dispersed.

  The black light absorption layer 15 is for absorbing the light transmitted through the optical multilayer film 12, and for example, FIG. 1 shows an embodiment in which a black resin film is attached to the outermost surface of the optical multilayer film 12. . Alternatively, it may be formed by applying a black paint.

  The screen 10 allows selective reflection to reflect light of a specific wavelength from the projector while transmitting and absorbing incident light in other wavelength regions such as external light while eliminating external light incident on the screen. A high contrast is achieved by lowering the black level of the image on the screen 10, and it is possible to display an image with high brightness and high contrast even in a bright room with ambient light as shown in FIG. . For example, when light from an RGB light source such as a diffraction grating type projector using a grating light valve (GLV) is projected, a good image with high contrast and no reflection of external light is appreciated on the screen 10 become able to.

  That is, the light incident on the screen 10 is collected in the bead layer 14 and reaches the optical multilayer film 12. Most of the external light component contained in the incident light is transmitted by the optical multilayer film 12 and absorbed by the black light absorption layer 15, and only light in a specific wavelength region related to the image is selectively reflected. Here, although the light in the specific wavelength region includes an external light component, since the incident angles of the projector light and the external light on the screen 10 are different, the external light among the reflected light of the optical multilayer film 12 is different. The component is returned to the ambient light source direction different from the projector position direction in the bead layer 14, and the projector light component is returned to the projector position direction (viewer). Therefore, it is possible to eliminate the influence of external light on the image light at a high level, and it is possible to achieve high brightness and high contrast that have not been possible in the past.

  As the reflective screen according to the present invention, an optical multilayer film having the same configuration as described above is formed on one surface (front surface) of a support, and an adhesive layer having the same configuration as described above is formed on the outermost surface of the optical multilayer film. It is good also as a structure by which the bead layer via was formed and the black light absorption layer was formed in the back surface of a support body. Even with this screen, the influence of external light on image light can be eliminated at a high level, and high brightness and high contrast can be achieved.

Here, the optical film materials A and B, which are paints for forming the first optical film 12H and the second optical film 12L, 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 composed of a lipophilic group and a hydrophilic group.
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 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 dispersant is composed of a lipophilic group and a hydrophilic group, and improves the dispersibility of the fine particles. The weight average molecular weight of the lipophilic group of the dispersant is 110 to 3000. If the molecular weight is lower than 110, there are problems such as insufficient dissolution in the organic solvent, and if the molecular weight exceeds 3000, sufficient dispersibility of the fine particles in the optical film cannot be obtained. The dispersant may have a functional group for causing a curing reaction with the binder.

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. The following functional groups as the polar functional group are useful because they do not aggregate. -SO ₃ M, -OSO ₃ M, -COOM, P = O (OM) ₂ (wherein M is a hydrogen atom or an alkali metal such as lithium, potassium or sodium), tertiary amine And quaternary ammonium salts. R ₁ (R ₂ ) (R ₃ ) NHX (wherein R ₁ , R ₂ and R ₃ are hydrogen atoms or hydrocarbon groups, X ⁻ is a halogen element ion such as chlorine, bromine and iodine or Inorganic and organic ions.) There are also 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 20 to 60 parts by weight, preferably 38 to 55 parts by weight with respect to 100 parts by weight of the fine particles.

  After the optical film material A is formed into a coating film by coating, the curing reaction is accelerated by radiation or heat, and the high refractive index type first optical film 12H is formed.

(2) Optical film material B
The optical film material B 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.
The fine particles are fine particles of a low refractive index material that is added as necessary to adjust the refractive index of the optical film after film formation, and are composed of SiO ₂ , MgF ₂ , hollow fine particles, or a fluorine-based resin. Fine particles are mentioned. Further, oxides such as Ti, Zr, Al, Ce, Sn, La, In, Y, and Sb, or alloy oxides such as In—Sn may be added. 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.

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 optical film material B is formed into a coating film by coating, the second optical film 12L having a lower refractive index than the first optical film is formed by a curing reaction.

  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.

Below, the manufacturing method of the reflective screen 10 which concerns on this invention is demonstrated below.
(S11) A polyethylene terephthalate (PET) film is prepared as the support 11, and the support 11 is dipped in a tank filled with the optical film material A, and a predetermined amount of optical material is applied to both surfaces of the support 11 by a dipping method. Film material A is applied.
(S12) The coating film of the optical film material A is dried to form an optical film 12H having a predetermined thickness.
(S13) Next, the support 11 on which the optical film 12H is formed is dipped in a tank filled with the optical film material B, and a predetermined amount of optical material is applied onto the optical film 12H on both surfaces of the support 11 by a dipping method. The film material B is applied.
(S14) 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.
(S15) Next, the support body 11 in which the optical films 12H and 12L are laminated is immersed 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 body 11 A predetermined amount of the optical film material A is applied.
(S16) 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 s13 to s16 are performed a predetermined number of times to form the optical multilayer film 12 on both surfaces of the support 11.

Hereinafter, the manufacturing process of the bead layer 14 will be described with reference to FIG.
(S17) A transparent adhesive is applied to the front surface of the optical multilayer film 12 to form a coating film 131 (FIG. 6A).
(S18) Next, a plurality of transparent spheres 141 are arranged on the coating film 131 so as to form one layer (FIG. 6B).
(S19) The transparent sphere 141 is pushed into the coating 131 by pressing (FIG. 6C).
(S1a) The coating film 131 is cured to form the transparent adhesive layer 13, and the bead layer 14 fixed by the adhesive layer 13 is formed on the optical multilayer film 12 (FIG. 6D).
(S1b) Next, a resin containing a black light absorbing agent is applied to the back surface of the optical multilayer film 12 to form a black light absorbing layer 15 to obtain 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.

The method for curing the coating 131 may be selected according to the type of adhesive used, such as heating or ultraviolet irradiation.
Alternatively, the bead layer 14 may be formed by spray coating a solution in which glass beads are dispersed in polyvinyl alcohol (PVA) on the optical multilayer film 12.

Next, a second embodiment of the reflective screen according to the present invention will be described.
The reflective screen 20 according to the present invention is the same as the first embodiment except that only the configuration of the adhesive layer is different from the reflective screen in the first embodiment. Hereinafter, the description will focus on the adhesive layer, which is a different part from the first embodiment.

FIG. 7 shows the configuration of the adhesive layer and the bead layer in the present embodiment.
The adhesive layer 23 has a two-layer structure in which a transparent layer 231 and a black layer 232 are laminated in order from the support 11 side. That is, in the bead layer 14, a plurality of transparent spheres 141 are arranged in one layer on the surface of the optical multilayer film 12, and a part of the transparent sphere 141 is formed through the transparent layer 231 and the black layer 232. 232 is a structure that is fixed in an exposed state from H.232. The transparent sphere 141 and the transparent layer 231 may be the same as those applied in the first embodiment.

  The black layer 232 is a black resin layer in which carbon black or a black pigment is dispersed, and the resin component may be the same as the resin component of the transparent layer 231.

FIG. 8 is a diagram illustrating the function of the black layer 232.
Of the light incident on the bead layer 14, the light incident from the front is narrowed by the lens effect of the transparent sphere 141 and hits the optical multilayer film 12 below the bead layer 14 as in the first embodiment. It is reflected, and the reflected light returns in the incident direction (FIG. 8A). On the other hand, the light incident obliquely on the bead layer 14 passes through the transparent sphere 141, is absorbed by the black layer 232, and is not emitted from the screen (FIG. 8B). As a result, light (ambient light) incident on the screen from other than the projector position can be absorbed, and the influence of the projector light on the reflected light (image light) can be eliminated.

  Further, as shown in FIG. 9, by adjusting the thickness of the black layer 232, it is possible to control the ratio of eliminating the influence of ambient light that becomes a disturbance of the projector light. That is, as the black layer 232 is thickened from FIG. 9A to FIG. 9C, light having a shallower incident angle is absorbed.

The reflection screen 20 of the present invention provides the following effects.
That is, the light incident on the screen is collected in the bead layer 14, and incident light (ambient light) from other than the projector position hits the black layer 232 and is absorbed. Further, incident light from the projector position reaches the optical multilayer film 12. Most of the external light component contained in the incident light is transmitted by the optical multilayer film 12 and absorbed by the black light absorption layer 15, and only light in a specific wavelength region related to the image is selectively reflected. Here, the light in the specific wavelength region may include an external light component, but since the incident angles of the projector light and the external light on the screen 20 are different, The external light component is returned to the ambient light source direction different from the projector position direction in the bead layer 14, and the projector light component is returned to the projector position direction (viewer). Therefore, it is possible to eliminate the influence of external light on the image light at a high level, and it is possible to achieve high brightness and high contrast that have not been possible in the past.

  Next, a method for manufacturing the reflective screen 20 according to the present invention will be described below. Here, the manufacturing process after the manufacturing process of the bead layer 14 which is different from the reflective screen 10 of the first embodiment will be described with reference to FIG.

(S27) A transparent adhesive is applied to the front surface of the optical multilayer film 12 to form a coating film 233 (FIG. 10A).
(S28) Next, a black adhesive is applied on the coating film 233 to form a coating film 234 (FIG. 10B).
(S29) Next, a plurality of transparent spheres 141 are arranged on the coating films 233 and 234 so as to form one layer (FIG. 10C).
(S2a) The transparent sphere 141 is pushed into the coating films 233 and 234 by pressing (FIG. 10D).
(S2b) The coating films 233 and 234 are cured to form the adhesive layer 23 of the transparent layer 231 and the black layer 232, and the bead layer 23 is fixed on the optical multilayer film 12 by the adhesive layer 23 (FIG. 10E).
(S2c) Next, a resin containing a black light absorbing agent is applied to the back surface of the optical multilayer film 12 to form a black light absorbing layer 15 to obtain a reflective screen 20 according to the present invention.

  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 composition and manufacturing method of the coating material (I), which is the optical film material A in Example 1, and the coating material (II), which is the optical film material B, and the screen manufacturing method are shown below.
(1) Paint (I)
Fine particles: TiO ₂ fine particles (Ishihara Sangyo Co., Ltd., average particle size of about 20 nm, refractive index 2.48) 100 parts by weight Dispersant: Silane coupling agent (Nihon Unicar Co., Ltd., A-174) 20 parts by weight Organic Solvent: 4800 parts by weight of methyl ethyl ketone First, a predetermined amount of the above-mentioned fine particles, a dispersant, and an organic solvent were mixed and subjected to dispersion treatment with a paint shaker to obtain a fine particle dispersion. As a binder for this fine particle dispersion, a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (trade name DPHA, manufactured by Nippon Kayaku Co., Ltd.), which is a UV curable resin, is added to 100 parts by weight of TiO ₂ fine particles. 33 parts by weight was added, and 3 parts by weight of Darocur 1173 as a polymerization initiator was added to the binder, followed by stirring with a stirrer to obtain paint (I). The paint had a viscosity of 2.3 cps and a specific gravity of 0.9 g / cm ³ .

(2) Paint (II)
The final composition of the coating material (II) for the low refractive index film is shown below.
Binder: Fluorinated ethylene copolymer resin (manufactured by Daikin Industries, Ltd., tetrafluoroethylene copolymer, solvent butyl acetate, solid content 50 wt%, refractive index 1.42) 20 parts by weight Organic solvent: methyl isobutyl ketone 100 parts by weight The viscosity of the coating material was 4.0 cps and the specific gravity was 0.84 g / cm ³ .

(3) Screen production method (s31) Paint (I) was applied by dipping on both sides of a transparent PET film (thickness: 188 μm, manufactured by Toray Industries, Inc., trade name: U426).
(S32) The coating film of paint (I) is dried at room temperature and then cured by ultraviolet (UV) (500 mJ / cm ² ) to form an optical film having a high refractive index of 850 nm per side.
(S33) Next, paint (II) was applied by dipping on the high refractive index optical film.
(S34) The coating film of paint (II) is dried at room temperature to form a low refractive index optical film having a thickness of 1020 nm.
(S35) The paint (I) is applied on the optical film (II) under the same conditions as in step s11.
(S36) The coating film of the paint (I) is dried at room temperature and then cured by ultraviolet (UV) (500 mJ / cm ² ) to form an optical film having a high refractive index of 850 nm per side. Thus, a three-layer optical multilayer film of optical film (I) / optical film (II) / optical film (I) was obtained on the PET film. The configuration is shown in FIG. Further, the reflection wavelength characteristic of the optical multilayer film is shown in FIG.

(S37) Next, as a hot melt adhesive layer on the front surface of the optical multilayer film, a polyester resin (Byron 200 manufactured by Toyobo Co., Ltd.) is controlled so that the thickness after drying is 30 μm by a blade coating method. Apply.
(S38) Glass beads having an average particle diameter of 50 μm (refractive index 2.25, density 4.6) are densely arranged on the coating film.
(S39) The one produced in step s38 is pressurized with a hot press machine at a temperature of 120 ° C. and a pressure of 3 kgf / cm ² , held for several minutes, and then cooled to room temperature.
By controlling the above conditions, a structure close to the optical design value (half the average particle size of 25 μm was embedded in the adhesive layer and the distance between the beads and the optical multilayer film was 5 μm) as shown in FIG. 13 was achieved.
(S3a) Next, a resin containing a black light absorbing agent was applied to the back surface of the optical multilayer film to form a black light absorbing layer, whereby the reflective screen of Example 1 was obtained.

  When light from an RGB light source of a projector using a high-pressure mercury lamp is projected onto the screen of Example 1 and the screen is viewed at the projector position, the luminance distribution is uniform, high luminance and high contrast, and external light It was confirmed that good images without reflection could be appreciated.

(Example 2)
An adhesive layer, a bead layer, and a black light absorbing layer were formed on the optical multilayer film of Example 1 by the following procedure to obtain a reflective screen of Example 2.
(S47) As a hot-melt adhesive layer on the front surface of the optical multilayer film, a polyester-based resin (Byron 200 manufactured by Toyobo Co., Ltd.) is applied so as to have a predetermined thickness after drying, and is applied by a blade coating method.
(S48) After drying the transparent coating film, as a black hot melt adhesive layer, a coating material in which carbon black is dispersed in the polyester resin is controlled to a predetermined thickness after drying and applied by a blade coating method. The coating film has a two-layer structure. The thicknesses of the first transparent coating film and the second black coating film were determined by optical design from the allowable angle of incidence of the external light on the screen.
(S49) Glass beads having an average particle diameter of 50 μm (refractive index 2.25, density 4.6) are densely arranged on the two-layered coating film prepared in step s48.
(S4a) The one produced in step s49 is pressurized with a hot press machine at a temperature of 120 ° C. and a pressure of 3 kgf / cm ² , held for several minutes, and then cooled to room temperature.
By controlling the above conditions, a structure close to the optical design value (half the average particle size of 25 μm was embedded in the adhesive layer and the distance between the bead and the reflective layer was 5 μm) was achieved.
(S4b) Next, a resin containing a black light absorbing agent was applied to the back surface of the optical multilayer film to form a black light absorbing layer, whereby a reflective screen of Example 2 was obtained.

  When light from an RGB light source of a projector using a high-pressure mercury lamp is projected onto the screen of Example 2 and the screen is viewed at the projector position, the brightness distribution is uniform, high brightness and high contrast, It was confirmed that good images without reflection could be appreciated.

It is sectional drawing which shows the structure of the reflection type screen which concerns on this invention. It is sectional drawing which shows the structure of the contact bonding layer and bead layer in 1st Embodiment of the reflection type screen which concerns on this invention. It is explanatory drawing of the retroreflection characteristic of a bead layer. It is a schematic diagram which shows the luminance distribution at the time of seeing the reflected light from the reflective screen which concerns on this invention from a projector position. It is a figure which shows the usage example of the reflection type screen which concerns on this invention. It is a manufacturing-process figure of the bead layer in 1st Embodiment of the reflection type screen which concerns on this invention. It is sectional drawing which shows the structure of the contact bonding layer and bead layer in 2nd Embodiment of the reflection type screen which concerns on this invention. It is explanatory drawing of the function of a black layer. It is a figure which shows the relationship between the thickness of the black layer in 2nd Embodiment, and the incident angle of the light absorbed. It is a manufacturing-process figure of the bead layer in 2nd Embodiment of the reflection type screen which concerns on this invention. It is sectional drawing which shows the structure of the optical multilayer film in an Example. It is a figure which shows the reflective wavelength characteristic of the optical multilayer film in an Example. It is sectional drawing which shows the structure of the contact bonding layer and bead layer in an Example. It is explanatory drawing of the reflective characteristic of the conventional reflective screen. It is a schematic diagram which shows the luminance distribution at the time of seeing the reflected light from the conventional reflective screen from a projector position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Reflective type screen, 11 ... Support body, 12 ... Optical multilayer film, 12H ... High refractive index optical film, 12L ... Low refractive index optical film, 13, 23 ... Adhesive layer, 14 ... Bead layer, 15 ... Black light absorption Layer, 141 ... transparent sphere, 231 ... transparent adhesive layer, 232 ... black layer, 131, 233, 234 ... coating film.

Claims (10)

On the support, a first optical film having a high refractive index and a second optical film having a lower refractive index are alternately laminated to form 2n + 1 (n is an integer of 1 or more) layers. An optical multilayer film having high reflection characteristics with respect to light in a specific wavelength region and having high transmission characteristics with respect to at least a visible wavelength region other than the specific wavelength region is formed,
A plurality of transparent spheres are arranged on one layer via an adhesive layer on the optical multilayer film, and a part of the transparent sphere is exposed from the adhesive layer and fixed to form a bead layer. Reflective screen.   The reflective screen according to claim 1, wherein the support is transparent, and the optical multilayer film is formed on both surfaces of the support.   The reflective screen according to claim 1, wherein the adhesive layer has a two-layer structure in which a transparent layer and a black layer are laminated in order from the optical multilayer film side.   The reflective screen according to claim 1, wherein the optical multilayer film has a laminated structure in which an outermost layer is formed of a first optical film. The first optical film is a film obtained by applying a material containing metal oxide fine particles, a dispersant and a binder, and the second optical film is a material containing fluorine-containing resin or SiO ₂ fine particles. The reflective screen according to claim 1, wherein the reflective screen is a film obtained by coating the film.   The reflective screen according to claim 1, wherein the specific wavelength region includes red, green, and blue wavelength regions.   The reflective screen according to claim 1, further comprising a black light absorbing layer on a back side of the support. 2n + 1 (n is an integer of 1 or more) having a high reflection characteristic for light in a specific wavelength region and a high transmission characteristic for at least a visible wavelength region other than the specific wavelength region on the support. .) Layered optical multilayer film, and a bead layer in which a plurality of transparent spheres are arranged in one layer on the optical multilayer film, and a part of the transparent spheres are exposed and fixed via an adhesive layer. A reflective screen manufacturing method,
The manufacturing process of the optical multilayer film includes:
A first coating step of forming a high refractive index first optical film by coating;
A second coating step of forming a second optical film having a refractive index lower than that of the first optical film by coating,
A method of manufacturing a reflective screen, comprising performing the first coating step and the second coating step alternately. The manufacturing process of the bead layer includes:
Applying a coating liquid containing a resin on the optical multilayer film to form a coating film;
Arranging a plurality of transparent spheres in one layer in the coating film and embedding so that a part of the transparent sphere is exposed from the coating film surface;
The method for manufacturing a reflective screen according to claim 8, further comprising a step of curing the coating film to form an adhesive layer.   The transparent coating film and the black coating film are applied in order from the optical multilayer film side, and the coating film has a two-layer structure in which a transparent layer and a black layer are laminated by curing. Method for manufacturing a reflective screen.

Images