JP2005202029A - Reflection type screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection type screen displaying a picture excellent in color reproducibility with high contrast without being influenced by the brightness of projection environment. <P>SOLUTION: The reflection type screen is equipped with an optical multilayered film 12 constituted by alternately laminating a 1st optical film 12H having a high refractive index and a 2nd optical film 12L having a lower refractive index than the 1st one on a base plate 11. The screen has high reflection characteristics to lights in a plurality of specific wavelength regions, and is provided with high transmission characteristic to at least light in a visible wavelength region other than the specific wavelength regions, and a light absorbing layer 13 having low transmittance to a wavelength region of 525 to 580nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reflection type screen, and more particularly to a projection type projector such as a video projector, a film projector, an overhead projector and the like. The present invention relates to a selective wavelength reflection type screen having a high contrast image and excellent color reproducibility.

  In recent years, overhead projectors and slide projectors have been widely used as methods for presenting materials by speakers in meetings and the like. In general households, video projectors and moving picture film projectors using liquid crystals are becoming popular. In these projector projection methods, light output from a light source is modulated by, for example, a transmissive liquid crystal panel to form image light, and the image light is emitted through an optical system such as a lens and projected onto a screen. Is.

  For example, a front projector capable of forming a color image on a screen separates light rays emitted from a light source into light rays of red (R), green (G), and blue (B) and puts them in a predetermined optical path. An illumination optical system that converges, a liquid crystal panel (light valve) that optically modulates light beams of RGB colors separated by the illumination optical system, and a light combining unit that combines light beams of RGB colors light-modulated by the liquid crystal panel The color image synthesized by the light synthesis unit is enlarged and projected on the screen by the projection lens.

Further, in the projector as described above, a projection screen is used to obtain a projection image. The projection screen is roughly divided into a transmission type in which projection light is irradiated from the back surface of the screen and viewed from the surface of the screen. There is a reflection type that irradiates projection light from the front side of the screen and sees the reflection light of the projection light on the screen.
In any method, in order to realize a screen with good visibility, it is necessary to obtain a bright image and an image with high contrast.

  However, unlike a self-luminous display or a rear projector, the front projector cannot reduce the reflection of outside light using, for example, an ND filter, and can increase the bright place contrast on the reflective screen. There was a problem that it was difficult.

  To solve this problem, the thickness of each optical film of the dielectric multilayer film is designed by simulation based on the matrix method, and has high reflection characteristics with respect to light in a specific wavelength region. A reflection type screen having an optical thin film (optical multilayer film) made of a dielectric multilayer film having high transmission characteristics for light in the visible wavelength range has been proposed (see, for example, Patent Document 1).

  In the above screen, the optical multilayer film serves as a so-called wavelength band filter, and most of light in a specific wavelength region is reflected by the action of the optical multilayer film. For example, when outside light is incident, most of the region other than the specific wavelength region is transmitted through the optical thin film and hardly reflected.

  As described above, the reflection type screen can selectively reflect only light of a specific wavelength, and can suppress reflection of external light relative to a normal screen, and thus is formed on the screen. In addition, a decrease in contrast of the image is suppressed and reflection of external light is effectively reduced, so that a bright image can be obtained. Also, with this reflective screen, a clear image can be obtained even when the projection environment is bright, and a clear image can be obtained without being affected by the brightness of the projection environment.

JP 2003-270725 A

  However, as described above, an optical multilayer film that selectively reflects or transmits light of a certain wavelength by a combination of optical films having a predetermined refractive index can control the film thickness in order to improve color reproducibility and color unevenness. However, there was a problem that it was required very strictly.

  That is, as shown in FIG. 6, for example, light from a high-pressure mercury lamp as a light source of a projector is red (R in the figure), green (G), and blue (B) by a selective wavelength reflecting film (reflected light absorbing film). However, since the light is broad and the peak intensity in the red wavelength region is low, the color balance is poor as it is, and the color reproducibility is lacking.

  When such a light source is used, if the film thickness is designed to selectively reflect in the wavelength region where the intensity of the light source of the projector changes greatly, the color unevenness is within the sun gend (3JND: Just Noticeable Difference, discrimination threshold). Therefore, strict film thickness control was necessary.

  An example is shown in FIG. FIG. 7 is a relationship diagram between the reflection characteristic (A) of the optical multilayer film and the light source spectrum (B) of the high-pressure mercury lamp. Here, the optical multilayer film has the same conditions as in the examples in the examples described later, except that the film thicknesses of the optical film (I) and the optical film (II) constituting the optical multilayer film are 660 and 940 nm, respectively. Formed.

  In FIG. 7, since the optical multilayer film has a selective wavelength transmission region in a region where the spectral intensity change of the light source is large (region C in the figure), the variation in the film thickness has a great influence on the color variation. In order to be within (3JND), the film thickness variation had to be strictly suppressed to ± 0.25%.

  Therefore, in order to moderate film thickness control, it is necessary to set the wavelength range of selective reflection to a region where the intensity change of the projector light source is small. Since the intensity of the area is weak, there is a problem in that when the image is projected on the screen, the green color becomes strong and the color reproducibility deteriorates.

  The present invention has been made in view of the above problems in the prior art, and provides a reflective screen capable of displaying an image with high contrast and excellent color reproducibility without being affected by the brightness of the projection environment. The purpose is to do.

The inventors tried to solve the above problem by providing a light absorption layer corresponding to the characteristics of each wavelength region of RGB of the light source.
As a related technique, Japanese Patent Application Laid-Open No. 5-216123 discloses a reflective screen that has a selective wavelength absorbing dye and selectively absorbs light in at least one wavelength region of wavelengths of 400 nm, 500 nm, 600 nm, and 700 nm. Is disclosed. As described above, a dye having a dye absorption half width within 20 nm has a certain kind of aggregate (for example, J aggregate) and lacks storage stability. Therefore, it is difficult to provide the light absorption film in each wavelength region of RGB. Met. In JP-A-6-82915, a light absorbing layer made of light absorbing ink is provided on the uppermost layer of the reflective screen, and the human eye has the highest specific visual sensitivity in the range of 575 nm within a range that does not destroy the gray balance. Although a technique for selectively absorbing light and improving the contrast of a projected image is disclosed, sufficient contrast and color reproducibility cannot be ensured only in the environment of bright outside light with the related technique alone. It was.
Therefore, as a result of intensive studies to optimize the light absorption characteristics of the light absorption layer in combination with the optical multilayer film, the present invention has been made.

  That is, the present invention provided to solve the above-described problems is a reflection type screen that reflects light from a light source to display an image. On the substrate, the first optical film having a high refractive index and a lower refractive index are provided. The second optical film having a refractive index is alternately laminated, has a high reflection characteristic for light in a plurality of specific wavelength regions, and has a high transmission characteristic for at least a visible wavelength region other than the specific wavelength region And a light absorbing layer having a low transmittance in the wavelength region of 525 to 580 nm.

  Here, the transmittance is preferably 35 to 65% at a wavelength of 540 nm.

  Moreover, it is preferable that the said light absorption layer contains either a pigment pigment | dye, a dye pigment | dye, a metal microparticle, and a metal covering fine particle.

  The light source is preferably any one of a high-pressure mercury lamp, a halogen lamp, and a xenon lamp.

  Each of the specific wavelength regions preferably includes one of red, green, and blue wavelength regions, and a light diffusion layer may be provided on the light absorption layer.

  According to the present invention, reflection of external light can be greatly suppressed as compared with a normal screen. As a result, it is possible to effectively reduce the contrast of an image formed on a projection screen and the reflection of external light. A bright image that can be reduced and has excellent color reproducibility can be obtained.

  Hereinafter, embodiments of the reflective screen according to the present invention will be described. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

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 reflective screen 10 has a configuration in which an optical multilayer film 12 that is a reflective layer, a light absorbing layer 13, a diffusion layer 14, and a protective layer 15 are provided on a substrate 11 in order. is there.

  The substrate 11 serves as a support for the reflective screen 10 and is made of a colorless polymer such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyolefin (PO), or the like. be able to.

Moreover, it is good also as a black board | substrate by making the board | substrate 11 contain a black coating material. Thereby, the substrate 11 itself functions as a black light absorption layer, and can absorb the light transmitted through the optical multilayer film 12 and prevent the reflected light from being reflected back.
In the screen of the present invention, this effect makes it possible to reliably obtain only the light of the three primary color wavelength bands as reflected light, thereby increasing the black level and improving the contrast. For the same purpose, a black layer may be provided on the back side of the substrate 11.

  Further, if a flexible material is used for the substrate 11, the reflective screen 10 having flexibility can be obtained.

  The optical multilayer film 12 is formed by alternately stacking a first optical film 12H having a high refractive index and a second optical film 12L having a refractive index lower than the first optical film 12H. An optical thin film having reflection characteristics and high transmission characteristics in at least a visible wavelength region other than the specific wavelength region.

  The optical multilayer film 12 includes, for example, a high refractive index optical film 12H that is a dielectric thin film formed of a high refractive index material by a dry method and a low refractive index that is a dielectric thin film formed of a low refractive index material. The dielectric thin film is formed by alternately overlapping the optical film 12L, and the structure of each layer of the dielectric multilayer film exhibits high reflection characteristics with respect to light in a specific wavelength region by simulation based on the matrix method. The film thickness may be designed so as to have high transmission characteristics for light in the visible wavelength region other than light in the wavelength region.

  Further, in the reflection type screen of the present invention, a red wavelength, a green wavelength and a blue wavelength are selected as specific wavelengths, and have high reflection characteristics for light in these wavelength regions by simulation based on a matrix method, It is designed to have high transmission characteristics for light in the visible wavelength region other than light in the wavelength region. For this, for example, an optical multilayer film proposed by the same applicant as the present applicant (JP-A-2003-270725, etc.) may be used.

The optical film 12H in this case can be made of a high refractive index material such as niobium pentoxide (Nb ₂ O ₅ ), titanium dioxide (TiO ₂ ), or tantalum pentoxide (Ta ₂ O ₅ ). The optical film 12L can be made of a low refractive index material such as silicon dioxide (SiO ₂ ) or magnesium fluoride (MgF ₂ ).

In the present invention, the constituent material of the optical film 12H is not limited to that described above, and various materials can be used as long as the refractive index is about 2.0 to 2.6. Similarly, the constituent material of the optical film 12L is not limited to that described above, and various materials having a refractive index of about 1.3 to 1.5 can be used.
The film thicknesses of the optical films 12H and 12L may be determined by calculation based on an optical simulation.

  Other embodiments of the optical multilayer film 12 include, for example, a first optical film 12H having a high refractive index formed by a wet method and a second refractive index having a lower refractive index formed by the wet method. It is good also as an optical thin film by which the optical film 12L is laminated | stacked alternately. In this case, in particular, the optical film 12H having a high refractive index is first provided on the substrate 11, followed by the optical film 12L having a low refractive index, and thereafter the optical film 12H and the optical film 12L are provided alternately. The optical film 12H is provided, and is preferably a laminated film composed of 2n + 1 layers (number of double-sided layers 2 (2n + 1)) (n is an integer of 1 or more) per side.

In this case, the optical film 12H is an optical film formed by a curing reaction after applying an optical film material A described later on the substrate 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 regions of red, green, and blue, and at least for light in the visible wavelength region other than these wavelength regions. It has transmission 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 an odd number layer of about 50 to 100 layers in the configuration by the dry method and an odd number layer of 3 to 7 in the configuration by the wet method. In any case, when the number of layers is less than the lower limit, the function as a reflective layer is not sufficient. On the other hand, the reflectance increases as the number of layers increases. However, when the number of layers exceeds the upper limit, the increase rate of the reflectance decreases, and the effect of improving the reflectance is obtained as the time required for forming the optical multilayer film 12 is increased. It is because it becomes impossible.

  The light absorption layer 13 is a film having a low transmittance in the wavelength region of 525 to 580 nm. This is to suppress an unbalance of the light emission intensity of the light source, for example, an excess of the light emission intensity in the green wavelength region in a high-pressure mercury lamp or the like.

  The transmittance is preferably 35 to 65% at a wavelength of 540 nm.

  The light absorption layer 13 is preferably a film having a high transmittance in the red wavelength region. This is because, for example, the light absorption layer 13 compensates for an imbalance between the excessive spectral intensity in the green wavelength region and the insufficient spectral intensity in the red wavelength region in a light source such as a high-pressure mercury lamp.

The red wavelength region is preferably a visible region of 600 nm or more, and the transmittance in that region is preferably 80% or more.
The maximum transmittance should be adjusted in relation to other spectra.

  In order to realize the above characteristics, the light absorption layer 13 preferably includes any one of a pigment coloring matter, a dye coloring matter, metal fine particles, and metal-coated fine particles, and all are preferably magenta materials.

The pigment dye is preferably a pigment red (PR) dye, for example, dichloroquinacridone (PR209) represented by the following structural formula. This dye has a minimum transmittance of 540 nm in the wavelength range of 525 to 580 nm (minimum transmission wavelength), and the transmittance is smaller than the minimum transmittance values in the blue and red wavelength regions.
Examples of the dye having similar characteristics include diketopyrrolopyrrole (PR254) having a minimum transmission wavelength of 544 nm and dimethylquinacridone (PR122) having a wavelength of 510 nm.
A dye pigment may be used, but a pigment pigment is preferable from the viewpoint of weather resistance.
Examples of the metal fine particles and metal-coated fine particles include gold colloid having a minimum transmission wavelength of 529 nm.

The light absorption layer 13 may be designed with the composition addition amount, film thickness, etc. in consideration of the transmittance in the target wavelength region.
FIG. 2 shows the light transmission characteristics of the light absorption layer containing the PR209 dye. Here, the film thickness is constant at 5 μm, the dye concentration of sample (1) is not added, and the dye concentration is increased in the order of samples (2) to (7). Specifically, in Samples (1) to (7), the dye was dispersed in an acrylic resin, but (1) to (7) were prepared by changing the pigment dye concentration at that time.
In FIG. 2, the transmittance at a wavelength of 540 nm tends to decrease as the dye concentration increases. When the concentration of the sample (7) is exceeded, the transmitted light is slightly reddish, and in the samples (2), (3), and (4), the transmitted light is greenish. In the case of this test, the transmitted light was able to obtain an appropriate white balance in the samples (5), (6), and (7).
In this case, the transmittance is related regardless of the film thickness. Therefore, when it is desired to reduce the film thickness, the dye concentration may be increased.

  The light source of the projector may be assumed to be any one of a high pressure mercury lamp, a halogen lamp, and a xenon lamp.

  The diffusion layer 14 is formed on the light absorption layer 13 and scatters the light reflected by the optical multilayer film 12 to obtain scattered light.

  Since the reflection type screen includes the optical multilayer film 12 and reflects light in the three primary color wavelength ranges, the observer views the reflection image of the image projected on the screen, that is, the reflection type screen. Only the reflected light of the image projected on is seen. However, when the reflected light on the screen is only the reflective specular component, it is difficult to visually recognize a good image, which is disadvantageous for an observer such as a limited field of view, and a natural image cannot be visually recognized.

  Therefore, the reflection type screen 10 of the present invention is configured so that the scattered reflected light from the screen 10 can be viewed by providing the diffusion layer 14. That is, with the configuration in which the diffusion layer 14 is provided on the optical multilayer film 12, the light incident through the diffusion layer 14 is selectively reflected by the optical multilayer film 12 in a specific wavelength region. However, at this time, the reflected light is diffused when passing through the light diffusion layer 14, and scattered reflected light other than the reflected specular component can be obtained. Since the reflected specular component and the scattered reflected light exist as the reflected light from the reflective screen 10, the observer can observe the scattered reflected light in addition to the reflected specular component. The characteristics are greatly improved. As a result, the observer can visually recognize a natural image.

  The diffusion layer 14 is not particularly limited, and a conventionally known one can be used. For example, the diffusion layer 14 can be constituted by a layer in which beads are arranged. The light diffusion layer constructed by arranging beads in this way has excellent light scattering characteristics for light in a specific range of wavelengths, depending on the conditions such as the type and size of the beads used. It is also possible to design. In addition, as the light diffusion layer, a film on which a microlens array (MLA) is formed can be used.

  The protective layer 15 is provided on the uppermost layer of the screen 10 and protects the optical multilayer film 12, the light absorption film 13, and the diffusion layer 14 from the external environment. For example, when the material constituting each of the optical multilayer film 12, the light absorption layer 13, and the diffusion layer 14 is weak against moisture and the reflective screen 10 is used in a high humidity environment, or when it is splashed with water, The multilayer film 12, the light absorbing layer 13, and the diffusion layer 14 may be deteriorated, and the durability and quality may be deteriorated. In addition, durability and quality may be deteriorated when an abrasion or scratch is caused by an external factor. The protective film 15 prevents the occurrence of defects and realizes the reflective screen 10 having excellent durability and quality.

  The reflection type screen 10 enables selective reflection by reflecting light of a specific wavelength from the projector and transmitting / absorbing incident light in other wavelength regions such as external light, and at the same time for each RGB wavelength region of the reflected light. It is possible to balance the emission intensity of the light. As a result, the black level of the image on the reflective screen 10 is lowered to achieve high contrast, and an image with high contrast and excellent color reproducibility 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. This makes it possible to view good images with excellent color reproducibility.

  That is, the light incident on the screen 10 reaches the optical multilayer film 12, and the external light component included in the incident light is transmitted through the optical multilayer film 12, and only light in a specific wavelength region related to the image is selectively selected. Reflected. Next, when the light source is, for example, a high-pressure mercury lamp, the reflected light is absorbed to some extent in the green wavelength region, and the light in the red wavelength region is transmitted with high transmittance. Are balanced, and are diffused on the surface of the diffusion layer 14 and provided to the viewer as image light having a wide viewing angle. Therefore, the influence of external light on the image light that is the reflected light can be eliminated at a high level, an unprecedented high contrast can be achieved, and an image excellent in color reproducibility can be provided.

  As the reflective screen according to the present invention, the optical multilayer film 12 having the same configuration as described above is formed on both surfaces of the substrate 11, and the light absorption layer 13, the diffusion layer 14, and the protective layer are formed on the optical multilayer film on one surface. 15 may be configured. This screen also reflects light of a specific wavelength from the projector and transmits and absorbs incident light in other wavelength regions such as outside light, thereby reducing the black level on the screen and providing excellent color reproduction with high contrast It is possible to achieve sex.

Here, the optical film materials A and B, which are paints for forming the first optical film 12H and the second optical film 12L by a wet method, 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.

Next, a method for manufacturing the reflective screen 10 will be described.
(S11) A polyethylene terephthalate (PET) film is prepared as the substrate 11, and the optical multilayer film 12 is formed on the substrate 11.

Here, in the case of the dry method, for example, a high refractive index material such as TiO ₂ , Nb ₂ O ₅ , Ta ₂ O _{5 and the} like as a high refractive index layer by an AC sputtering method, and SiO ₂ as a low refractive index layer, for example. The optical films 12H and 12L are formed by alternately stacking low refractive index materials such as MgF ₂ . At this time, the thickness of each layer is designed according to the wavelength range of the light used.

  Further, when the wet method is used, the optical films 12H and 12L are laminated and formed by alternately applying and curing the optical film materials A and B on the substrate 11 by dipping. At this time, it is not easy to apply the optical film material A onto the optical film 12L, but it can be applied by optimizing its viscosity, solid content, solvent and the like to increase dispersibility.

(S12) The light absorption layer 13 is formed on the optical multilayer film 12 by applying and curing a paint in which a predetermined pigment and a polymer material such as an acrylic resin are mixed.

(S13) A transparent adhesive having a low refractive index (EPOTEK396 manufactured by EPOXY TECHNOLOGY) is applied on the light absorption layer 13, and the opposite surface of the plate-shaped diffusion layer 14 is mounted as a contact surface. After that, the adhesive is cured to form an adhesive layer that bonds the light absorption layer 13 and the diffusion layer 14 together.

(S14) A protective layer is formed on the diffusion layer 14 to obtain the reflective screen 10.

  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)
The composition and manufacturing 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 and the manufacturing method of the optical multilayer film are shown below.
(1) 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).
(2) Optical film material B (paint (II))
・ Polyfluorobutenyl vinyl ether polymer with terminal carboxyl group (product name: Cytop, manufactured by Asahi Glass Co., Ltd.)

(3) Optical multilayer film manufacturing method (s11) The coating material (I) is apply | coated by the dipping system on both surfaces of a transparent substrate (refractive index 1.59).
(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 with a film thickness of 780 nm and a refractive index of 1.94 (wavelength 550 nm) ).
(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 film thickness of 1120 nm and a refractive index of 1.35 (wavelength 550 nm).
(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.

FIG. 3 shows the relationship between the reflection characteristics of the optical multilayer film and the light source spectrum of a projector using a high-pressure mercury lamp. In FIG. 3, A is the reflection characteristic of the optical multilayer film, R is the light source spectrum in the red region, G is the light source spectrum in the green region, and B is the light source spectrum in the blue region.
With this configuration of the optical multilayer film, the variation in film thickness is allowed to be within ± 1.5% in order to keep the color unevenness within the sun gend (3JND), so that the manufacturing yield can be improved. It becomes possible.

  Next, a coating material in which PR209 dye and acrylic resin were mixed was applied and cured on the optical multilayer film to form a 5 μm-thick light absorption layer having the light absorption characteristics of the sample (7) in FIG. In addition, a diffusion film was bonded to the surface of the light absorption layer via an adhesive layer, and a protective layer was formed to obtain a reflective screen.

When image light was projected onto the obtained reflective screen from a projector using a high-pressure mercury lamp, it was confirmed that an image with high contrast and excellent color reproducibility was displayed. Further, white light was projected from the projector, and the spectrum of the reflected light was measured. The result is shown in FIG. Moreover, the result of having produced the reflection type screen of the structure which abbreviate | omitted the light absorption layer in the structure of an Example and measuring the reflected light spectrum similarly is shown in FIG. 5 as a comparative example.
It was confirmed that the reflected light spectra of the examples were more balanced in the spectral intensities in the red, green, and blue wavelength regions than the comparative examples.

It is sectional drawing which shows the structure of the reflection type screen which concerns on this invention. It is a figure which shows the light absorption characteristic of a light absorption film. It is a figure which shows the relationship between the reflective characteristic in the reflective screen of an Example, and the light source spectrum of the projector using a high pressure mercury lamp. It is a figure which shows the reflected light spectrum in the reflection type screen of an Example. It is a figure which shows the reflected light spectrum in the reflection type screen of a comparative example. It is a figure which shows the light source spectrum of a high pressure mercury lamp. It is a figure which shows the relationship between the reflective characteristic in the optical multilayer film which has a selective wavelength transmission area | region in the area | region where the spectrum intensity change of a light source is large, and the light source spectrum of the projector using a high pressure mercury lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Reflective type screen, 11 ... Substrate, 12 ... Optical multilayer film, 12H ... High refractive index optical film, 12L ... Low refractive index optical film, 13 ... Light absorption layer, 14 ... Diffusion layer, 15 ... Protective layer

Claims (6)

In a reflective screen that reflects light from a light source and displays an image,
A first optical film having a high refractive index and a second optical film having a lower refractive index are alternately laminated on the substrate, and has high reflection characteristics for light in a plurality of specific wavelength regions. And a reflective screen comprising: an optical multilayer film having a high transmission characteristic for at least a visible wavelength region other than the specific wavelength region; and a light absorption layer having a low transmittance in a wavelength region of 525 to 580 nm. .   The reflection type screen according to claim 1, wherein the transmittance is 35 to 65% at a wavelength of 540 nm.   The reflective screen according to claim 1, wherein the light absorption layer includes any one of a pigment pigment, a dye pigment, metal fine particles, and metal-coated fine particles.   The reflective screen according to claim 1, wherein the light source is any one of a high-pressure mercury lamp, a halogen lamp, and a xenon lamp.   The reflective screen according to claim 1, wherein each of the specific wavelength regions includes any one of red, green, and blue wavelength regions. The reflective screen according to claim 1, further comprising a light diffusion layer on the light absorption layer.

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