JP2006337906A - Light diffusion film and screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusion film which has the anisotropy in light diffusion characteristic in the longitudinal and lateral directions, prevents dusts from sticking to the light diffusion film and a mold during production and hardly degrades the anisotropy of diffusion angle even in a long-term use in user, and to provide a screen using the light diffusion film. <P>SOLUTION: The light diffusion film comprises a translucent support 11 and a translucent resin layer 12 having a rugged light diffusion surface on a surface disposed on the translucent support 11, and has the anisotropy of diffusion angle, wherein surface resistivity of the light transmissive resin layer 12 is 1×10<SP>11</SP>Ω or less and pencil hardness is H or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light diffusing film used for a front projector screen, a rear projector screen, a liquid crystal display backlight, and the like, and a screen using the light diffusing film.

  In recent years, overhead projectors and slide 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. 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.

  In the projector apparatus described above, a projector screen is used to view a projected image. This projector screen is roughly divided into a front projector screen for irradiating projection light from the front side of the screen and viewing the reflected light on the screen, and a projection light from the back side of the screen for transmission through the screen. There is a rear projector screen for viewing light from the front side of the screen. Any type of screen is required to have a wide viewing angle with good visibility.

  For this reason, a light diffusing sheet that scatters light is generally provided on the screen surface in any of the methods, and image light is diffused and emitted to the entire effective area of the screen by the light diffusing sheet.

  Isotropic light diffusing film and anisotropic light diffusing film are known as light diffusing film roughly, but since the amount of incident light is constant, improving the brightness by diffusing light only in the necessary direction An anisotropic light diffusing film that can be used has attracted attention. In particular, when used as a projection screen, a horizontal visual field is more important than a vertical visual field. Therefore, development of an anisotropic light diffusion film having a strong diffusing ability in the horizontal direction has been underway.

  As a method for producing this anisotropic light diffusing sheet, conventionally, a speckle pattern generated when a rough surface is irradiated with a coherent light beam is formed on a photosensitive resin (for example, see Patent Documents 1 and 2), and a mask. A method of creating and baking onto photosensitive resin, or forming a mold with minute irregularities by cutting the surface of a metal base material such as metal or resin directly by machining, and then using UV curable resin etc. There was a method of transferring.

  Also, a method in which resin particles are dispersed in a resin binder is applied to a transparent substrate, or a mold in which irregularities are formed on the surface of a mold base material by sandblasting, and UV curing is performed from this mold. There has been a method of shape transfer using a resin or the like (see, for example, Patent Document 3).

JP-A-53-51755 Japanese Patent Laid-Open No. 2001-1000062 JP 2000-284106 A

  However, the conventional anisotropic light diffusing film has a problem in that the displayed resin is deteriorated due to damage of the constituent resin. There is also a problem that the anisotropy of the diffusion angle is lost over time.

  The present invention has been made in view of the above-described problems in the prior art, has anisotropy in light diffusion characteristics in the vertical and horizontal directions, and prevents dust from adhering to the light diffusion film and mold during production. An object of the present invention is to provide a light diffusing film with little decrease in the diffusion angle anisotropy even for long-term use by a user, and to provide a screen using the light diffusing film.

  The inventors investigated the above problem and found out that it was caused by the fact that fine dust and dust were likely to adhere to the surface of the light diffusion film. In other words, the resin of the constituent material is damaged by the adhesion of the dust and the like, causing image degradation. In addition, the light diffusion due to the dust and dust is isotropic with almost no anisotropy, and the dust is deposited on the surface of the light diffusion film over time, so that the initial diffusion angle is different. It was also found that the directionality was gradually lost. Further, there is a drawback that the surface of the light diffusion film is easily damaged due to adhesion of the dust and the like. The inventors have intensively studied from the viewpoint of preventing the adhesion of dust and the like, and have come to achieve the present invention.

That is, the present invention provided to solve the above problems includes a translucent support, and a translucent resin layer having an uneven light diffusing surface on the surface provided on the translucent support. A light diffusing film having an anisotropic diffusion angle, wherein the translucent resin layer has a surface resistance of 1 × 10 ¹¹ Ω or less and a pencil hardness of H or more. (Claim 1).

Here, it is preferable that the translucent resin layer contains a surfactant in the resin.
Moreover, it is preferable that the uneven | corrugated shape of the said light-diffusion surface is what the shape of the metal mold | die surface formed by the sandblasting process made so that the spraying angle of an abrasive material was less than 90 degrees was transferred.

  Moreover, this invention provided in order to solve the said subject is the reflection provided in the light-diffusion film as described in any one of Claims 1-3, and the surface opposite to the light-diffusion surface of this light-diffusion film. A screen comprising a layer (claim 4).

  Moreover, this invention provided in order to solve the said subject is provided with the light-diffusion film as described in any one of Claims 1-3, and this light-diffusion film is from the surface opposite to the said light-diffusion surface. The screen is characterized in that the projection light is transmitted and diffused and emitted from the light diffusion surface.

According to the light diffusing film of the present invention, the light diffusing property is anisotropic in the vertical and horizontal directions, and the light diffusing film and the mold can be prevented from being attached during production. For example, when a light diffusion film is manufactured by continuously forming a film using a roll mold, it is possible to suppress the failure with dust.
In addition, according to the screen of the present invention, it is possible to suppress a decrease in the diffusion angle anisotropy even during long-term use by the user.

Below, embodiment of the light-diffusion film which concerns on this invention is described.
FIG. 1 is a cross-sectional view showing a configuration of a light diffusion film according to the present invention.
As shown in FIG. 1, the light diffusing film 10 is composed of a translucent support 11 and a translucent resin layer 12 having irregularities on the surface provided on the translucent support 11, and has a diffusion angle. It is anisotropic. Further, the surface resistance of the light diffusion film 10 is 1 × 10 ¹¹ Ω or less. The surface resistance is more preferably 8 × 10 ¹⁰ Ω or less. In addition, the surface resistance value as used in the field of this invention is a value measured by normal temperature (25 degreeC) and normal humidity (55% RH) using a commercially available surface resistance measuring device. The light diffusion film 10 has a pencil hardness of H or higher.

  The translucent support 11 is not particularly limited, and for example, a polyester resin such as polyethylene terephthalate, a polyolefin resin such as triacetyl cellulose or polypropylene, a polycarbonate resin, or a vinyl chloride resin sheet or film is preferable. The thickness of the translucent support 11 is preferably 20 μm to 300 μm. If it is thinner than this, the strength is insufficient, and if it is thicker than this, the production handleability deteriorates. In order to improve the adhesiveness with the translucent resin layer 12, the translucent support 11 may be provided with an easy adhesion layer on the surface, or may be subjected to corona discharge treatment or plasma treatment.

The translucent resin layer 12 is an optical film whose surface shape is controlled by an uneven state such as a circle, a rectangle, or a polygon so as to exhibit anisotropy in the diffusion angle. Further, the surface irregularities may be formed by transferring the fine irregularities formed on the mold onto the surface of the optical material. For example, such a mold is pressed into a thermoformed plastic film by pressing. Or the like.
Alternatively, a translucent resin layer having desired irregularities can be obtained by applying and curing a radiation curable resin to the mold and removing the mold.

  The resin material used here is not particularly limited as long as it is translucent and has a predetermined dynamic viscoelasticity, but it is not preferable that the hue of transmitted light and the amount of transmitted light change due to coloring and haze. From the viewpoint of ease of production, resins that can be cured by ultraviolet rays, electron beams, and heat are preferred, and most preferably those that can be cured by ultraviolet rays. For example, acrylate resins such as urethane acrylate, epoxy acrylate, polyester acrylate, polyol acrylate, polyether acrylate, and melamine acrylate can be used.

  Further, the translucent resin layer 12 preferably contains an anion, a cation, or a nonionic surfactant in the resin constituting the translucent resin layer 12. For example, sodium alkylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium alkylsulfonate, bisalkylsulfonimide, sodium dialkylsulfosuccinate, glycerin fatty acid ester, sorbitan monofatty acid ester, polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, methoxy Examples include polyethylene glycol, polyethylene glycol monolaurate, and polyethylene glycol monostearate.

In the case of an anionic or cationic surfactant, the addition amount of the surfactant is preferably 0.1 wt% or more and 10 wt% or less. More preferably, it is 0.2 wt% or more and 5 wt% or less. Moreover, in the case of a nonionic surfactant, 1 wt% or more and 20 wt% or less are preferable. More preferably, it is 5 wt% or more and 20 wt%. Moreover, even when mixing and using various surfactant, 1 wt% or more and 20 wt% or less are preferable. When the addition amount of the surfactant is less than the lower limit, no improvement in dust adhesion is observed. When the addition amount is more than the upper limit, the strength of the translucent resin layer 12 is reduced and the adhesiveness of the surface is increased. Is unsuitable because it tends to adhere.
In addition, as a method for adding the surfactant, it is preferable to add and mix in the stage of the resin composition before forming the translucent resin layer 12.

  In addition, a light stabilizer, an ultraviolet absorber, an antistatic agent, a flame retardant, an antioxidant, and the like can be appropriately used for the translucent resin layer 12 as necessary.

Although there is no limitation in particular as the thickness of the translucent resin layer 12, 20 micrometers or more and 200 micrometers or less are preferable. If it is thinner than this, the surface shape is likely to be lost, and if it is thicker than this, cracking of the film is likely to occur and the handleability is lowered.
Further, examples of the curing energy source for forming the translucent resin layer 12 include an electron beam, ultraviolet rays, visible rays, and gamma rays, and ultraviolet rays are preferable from the viewpoint of production equipment. Further, the ultraviolet ray source is not particularly limited, and a high-pressure mercury lamp, a metal halide lamp, or the like is appropriately used. The integrated irradiation dose is appropriately selected so that the resin used is sufficiently cured and the resin and the transparent support 11 are sufficiently adhered, and the resin and the transparent support 11 are not yellowed. it can. The irradiation atmosphere can be appropriately selected according to the degree of resin curing, and can be performed in air or in an inert atmosphere such as nitrogen or argon.

  Moreover, since the light-diffusion film 10 is used as an optical element, it is necessary to use the light from a light source efficiently, it is preferable to have a high transmittance, and the total light transmittance is preferably 80% or more.

  With the above configuration, the light diffusing film 10 has anisotropy in light diffusing characteristics in the vertical and horizontal directions, prevents dust from adhering to the light diffusing film and the mold at the time of manufacture, and diffuses even for long-term use by users. It is possible to suppress a decrease in angular anisotropy.

Below, the manufacturing method of the light-diffusion film of this invention is demonstrated.
The method for producing a light diffusing film according to the present invention uses a translucent resin layer replication mold in which a fine engraving surface having a predetermined concavo-convex shape is formed on a translucent support 11. The light diffusing film 10 is formed by transferring the concavo-convex shape on the surface of the mold to form a translucent resin layer having concavo-convex on the surface.

Here, the present invention can be applied to any manufacturing method as long as it is a method for manufacturing a translucent resin layer from the fine engraving surface of the mold. Here, the mold to be used may be a roll mold having a cylindrical shape and a fine engraving surface formed on a cylindrical surface, or a flat plate mold having a fine engraving surface formed on a flat surface. .
For example, the light-transmitting resin layer may be formed by pressing the mold onto a thermoformed plastic film by pressing.
Alternatively, a desired light-transmitting resin layer can be obtained by applying and curing an ultraviolet curable resin to the mold and removing the mold.

Hereinafter, the procedure for manufacturing the light diffusing film 10 shown in FIG. 1 will be described by taking as an example the case where an ultraviolet curable resin is used as the optical film material constituting the translucent resin layer.
(S11) A translucent resin material is poured into the fine engraving surface of the translucent resin layer replication mold having a fine engraving surface having a predetermined uneven shape on the surface. Note that a sealing material is attached to the four sides of the mold so that the translucent resin material does not leak.
(S12) The translucent support 11 is placed in the form of a film on the coating film of the translucent resin material of the mold.
(S13) Ultraviolet rays are irradiated from the translucent support 11 side, the translucent resin material is cured, and the translucent resin layer 12 is formed.
(S14) The mold is removed from the translucent resin layer 12, and the light diffusion film 10 composed of the translucent resin layer 12 / the translucent support 11 is obtained.

  The translucent resin material is appropriately selected from the translucent resin materials shown above so that the surface resistance of the produced light diffusion film 10 becomes a target value, and a surfactant is appropriately added. That's fine.

  Here, in order to set the diffusion angle of the light diffusing film 10, the uneven shape and size of the fine engraving surface of the translucent resin layer replication mold or the refractive index of the translucent resin layer 12 can be adjusted. Good.

What is necessary is just to manufacture the translucent resin layer replication metal mold | die used here by the method by sandblasting as shown, for example.
FIG. 2 shows a state where a mold used for replicating a light diffusion film is manufactured. The surface of the mold base material 1 is processed by sandblasting to manufacture a translucent resin layer replication mold. To do. At this time, the shape of the mold base material is not limited to a lithographic plate, but may be a shape suitable for continuous film formation such as a roll shape or a conveyor shape.

  Sand blasting is performed by injecting abrasive 3 from a blast gun 2 of a sand blasting device (not shown) with pressurized air and spraying it onto the surface of the mold base 1. This is a process in which irregularities are formed on the surface of the mold base material 1 by collision.

  As the abrasive 3, a polygonal ceramic having a particle size of 1 μm to 50 μm is used. However, the present invention is not limited to this, and a spherical or polygonal shape made of resin, glass, metal, ceramics, etc. Are preferred. Examples thereof include glass beads, zirconia particles, steel grids, alumina particles, silica particles, and the like.

  The mold base material 1 is a sheet made of a material suitable for sandblasting. This material is preferably a resin or metal, such as aluminum, copper, or steel, and aluminum is particularly preferable. In addition, the mold base material 1 may be a size that can correspond to the size of the light diffusing film applied to the screen in batch production, and corresponds to the width of the light diffusing film in continuous production. Any size can be used.

  Moreover, it is preferable that the spraying angle (the depression angle) of the grinding material 3 is less than 90 ° with respect to the main surface of the mold base material 1, and in the present invention, the spraying direction and the direction thereof are controlled by spraying at 10 °. It is possible to change the pitch of the grooves in the direction perpendicular to the direction. This is because the abrasive 3 collides with the mold base 1 at an angle, and the deformed shape caused by the collision differs between the horizontal direction (X-axis direction) and the vertical direction (Y-axis direction). The surface roughness parameters such as the pitch can be adjusted by changing the sandblasting conditions. When using a grinding material with a large grain size, a large pitch roughness can be realized in both the X and Y axis directions, resulting in higher density. If a large abrasive is used, a deep groove shape can be realized.

By using the translucent resin layer replication mold manufactured under the above spraying conditions, the translucent resin layer 12 has different diffusion angles in the vertical and horizontal directions, or is anisotropic in diffusion characteristics in the vertical and horizontal directions. There can be. For example, under the spraying condition of the abrasive 3 in FIG. 2, the diffusion angle of reflected light or transmitted light is narrow in the X direction and wide in the Y direction.
Further, as the blast gun 2 is laid on the mold base material 1, that is, as the angle θ is reduced, the aspect ratio of the diffusion angle of the light diffusion film described later can be increased, and the anisotropy of the diffusion characteristics can be increased. Great effect.

The abrasive 3 is injected from the blast gun 2 with an angle width α about the angle θ with respect to the mold base 1. In other words, the abrasive material 3 enters and collides with the mold base material within the range of angles β ₁ to β ₂ . The angular width α is usually about 10 °.

  When processing a smaller region of the mold base material 1, the angle width α may be made smaller, or the distance L between the blast gun 2 and the mold base material 1 may be made smaller. In order to process a wider area, sandblasting may be performed while moving the blast gun 2 or the mold base material 1 smoothly. In the present invention, the blast gun 2 is scanned vertically and horizontally on the mold base material 1. It is preferable to perform sandblasting on the entire main surface of the mold base 1.

  A scan example of the blast gun 2 is shown in FIG. While the abrasive 3 is emitted from the blast gun 2, the blast gun 2 is moved at a constant speed in one direction of the Y axis on the mold base 1, and the collision area of the abrasive 3 is near the end face of the mold base 1. Is reached, the X-axis direction is moved at a constant pitch, and the blast gun 2 is moved at a constant speed in the opposite direction to the Y-axis. Thereafter, whenever the collision area of the abrasive 3 reaches the vicinity of the end face of the mold base 1, the blast gun 2 is moved in the X-axis direction at a constant pitch, and then the movement in the Y-axis direction is reversed to perform sand blasting. Continuously, desired irregularities are formed on the entire surface of the mold base material 1.

  The movement pitch in the X-axis direction is preferably adjusted so that the collision areas of adjacent abrasives 3 overlap to some extent, and the entire surface of the mold base 1 has a uniform uneven shape. Further, a mask may be applied to the collision area of the abrasive 3 so that only the center area of the collision area collides with the mold base material 1.

  Regarding the scanning method, the mold base material 1 may be fixed and the blast gun 2 may be moved, or the stage on which the mold base material 1 is placed is moved in the X-axis direction, and the blast gun 2 is moved to the Y direction. You may make it move to an axial direction.

  By the sand blasting process, a concave and convex fine engraving surface is formed on the surface of the mold base material 1. This uneven shape becomes a prototype of the surface shape of the translucent resin layer 12 which is the final product, and the translucent resin layer 12 may be formed using this fine engraving surface.

  In the present invention, the present invention can be applied to any manufacturing method as long as the translucent resin layer 12 is formed from the fine engraving surface. For example, a method of manufacturing an electroformed mold having the fine engraved surface transferred thereon using a substrate on which the fine engraved surface is formed, and then directly or indirectly forming the translucent resin layer 12 using the electroformed mold It's okay.

  The above is an example of sandblasting as a manufacturing process of a translucent resin layer replication mold, but the manufacturing method is not limited to this, and speckles generated when a rough surface is irradiated with a coherent light beam are used. Forming a pattern by forming a pattern on a photosensitive resin, creating a mask and baking it on the photosensitive resin, or cutting a metal base material such as metal or resin directly by machining to form minute irregularities Any method may be used as long as it can form fine irregularities on the surface.

Next, the configuration of the screen according to the present invention will be described.
FIG. 4 is a sectional view showing the configuration of the screen according to the first embodiment of the present invention.
The screen 100 is a reflective screen having a configuration including the reflective sheet 50 and the light diffusion film 10. The light diffusion film 10 may be formed directly on the reflection sheet 50 or may be bonded to the reflection sheet 50.

  The reflection sheet 50 has reflection characteristics with respect to light in a plurality of specific wavelength regions corresponding to projector light that is image light, and has absorption characteristics with respect to light in the visible wavelength region excluding the plurality of specific wavelength regions. . Here, the specific wavelength region preferably includes a wavelength region of light of each of the three primary colors RGB used as image light by the projector light source.

  FIG. 5 shows an example in which the reflective sheet 50 includes an optical multilayer film 52 composed of a metal oxide film 52D, a light-absorbing thin film 52M having transparency, and a reflective layer 51.

  Here, the reflective layer 51 has a metal film 51M formed on the substrate 51B, and reflects the light transmitted through the optical multilayer film 52.

  The substrate 51B serves as a support for the reflective sheet 50. For example, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyolefin (PO) or the like is acceptable. Examples thereof include a polymer having flexibility.

The metal film 51M may be any metal material that reflects visible light with high reflectivity. For example, it is made of Al, Au, or Ag, and a film thickness of 50 nm or more is preferable. As a method for forming the metal film 51M on the substrate 51B, any method such as vapor deposition, plating, or coating may be used.
As the reflective layer 51, a metal substrate made of the same material as the metal film 51M may be used instead of the metal film 51M formed on the substrate 51B of FIG.

  The optical multilayer film 52 is a film having selective reflection characteristics of at least two layers including a metal oxide film 52D and a light-absorbing thin film 52M having transparency. In this case, the metal oxide film 52D and the light-absorbing thin film 52M having transparency may be alternately stacked, or a structure in which a plurality of types of metal oxide films 52D are continuously stacked may be used.

The metal oxide film 52D is made of a transparent material at least in the visible wavelength region. For example, Nb ₂ O ₅ (niobium pentoxide), TiO ₂ (titanium dioxide), Ta ₂ O ₅ (tantalum pentoxide), Al ₂ O ₃ Transparent dielectric film such as (aluminum oxide) or SiO ₂ (silicon dioxide), or In ₂ O ₃ (indium oxide), SnO ₂ (tin oxide), ZnO (zinc oxide), In ₂ O ₃ —SnO ₂ compound A transparent conductive film made of (ITO) or a material in which any of these is doped with metal (for example, ZnO: Al, ZnO: Ga) is used. In addition, it is necessary because the half-value width of the reflection peak in the wavelength region of each color light in the three primary color wavelength regions increases as the refractive index of the metal oxide film 22D increases, and the half-value width tends to decrease as the refractive index decreases. A metal oxide material may be appropriately selected according to the selective reflection characteristic.

The light-absorbing thin film 52M having transparency is a thin film formed of a material having a refractive index of 1 or more and an absorption coefficient of 0.5 or more, preferably in a thickness of 5 to 20 nm. Examples of such materials include Nb, Nb-based alloys, C, Cr, Fe, Ge, Ni, Pd, Pt, Rh, Ti, TiN, TiN _x W _y , Mn, Ru, and PbTe. Each film of the optical multilayer film 52 may be formed by a dry process such as sputtering.

Each film thickness of the optical multilayer film 52 has, for example, high reflectivity with a reflectance of 50% or more, for example, with respect to light in the three primary color wavelength regions composed of light in the wavelength regions of red, green, and blue. For light in a wavelength region other than the wavelength region, it is designed to have a high absorption characteristic with an absorptivity of 80% or more, for example. Here, each film thickness of the optical multilayer film 52 is such that the thickness of each film is d, the refractive index of each film is n, and the wavelength of light incident on the optical multilayer film is λ. The target thickness nd is preferably designed so as to satisfy the following expression (1) with respect to the wavelength λ of the incident light.
nd = λ (α ± 1/4) (1)
(However, α is a natural number.)

For example, the metal film 51M is an Al film (film thickness 50 nm), and the optical multilayer film 52 is a three-layer film of Nb ₂ O ₅ / Nb / Nb ₂ O ₅ (each film thickness: 560 nm / 19 nm / 550 nm (Al film side)). With the structure, the projector light (light from the projector light source using the laser oscillator) has a high reflectance of 50% or more for the light of the three primary colors, and the wavelength range before and after the three primary colors wavelength range. It can be set as the reflective sheet 50 which has a high absorption factor of 80% or more with respect to light (stray light).

  Alternatively, in the case where the external light is light of a halogen lamp, the wavelength region having an absorption characteristic is set between the wavelength of the bright line peak of the red component and the wavelength of the green line of the planned light source, and the wavelength of the green component. It is preferable to design the optical multilayer film 22 so as to be disposed between the wavelength of the emission line peak and the wavelength of the emission line peak of the blue component.

For example, the metal film 51M is an Al film (film thickness 100 nm), and the optical multilayer film 52 is an Nb ₂ O ₅ / Nb / Nb ₂ O ₅ (each film thickness: 330 nm / 3 nm / 450 nm (Al film side)) three layers With the structure, in the emission line spectrum of the light source (for example, UHP lamp), between the emission line peak at a wavelength of 440 nm and the emission line peak at 550 nm, and between the emission line peak at 550 nm and the emission line peak at 610 nm. The wavelength region (absorption peak) having the absorption characteristics of the reflection sheet 50 can be between the wavelengths 570 nm and 600 nm and between 500 nm and 530 nm.

  In FIG. 6, as another configuration of the reflection sheet 50, the reflection sheet 50 has reflection characteristics with respect to light in the wavelength regions of light of the three primary colors of RGB among the wavelength regions of the projector light on the substrate 51 </ b> B. An example in which an optical multilayer film 53 having transmission characteristics for light and a light absorption layer 54 on the back surface of the substrate 51B is shown. Here, the substrate 51B may be the same as the substrate shown in FIG.

  The optical multilayer film 53 is formed by stacking a plurality of types of optical films having different refractive indexes. For example, the high refractive index film 53H and the low refractive index film 53L having a lower refractive index than the high refractive index film 53H are alternately arranged. It is a film having selective reflection characteristics laminated on.

  The high refractive index film 53H and the low refractive index film 53L can be formed by any of a dry process such as a sputtering method or a wet process such as spin coating or dip coating.

In the case of forming by a dry process, various materials can be used as the constituent material of the high refractive index film 53H as long as the refractive index is about 2.0 to 2.6. Similarly, the constituent material of the low refractive index film 53L has a refractive index of about 1.3 to 1.5, and various materials can be used. For example, the high refractive index film 53H may be made of TiO ₂ , Nb ₂ O ₅ or Ta ₂ O ₅ , and the low refractive index film 53L may be made of SiO ₂ or MgF ₂ .

When formed by a dry process, the thickness of each optical multilayer film 53 is such that the optical thin film has a high reflection characteristic with respect to light in a specific wavelength band by simulation based on the matrix method, and at least visible light other than the wavelength band light is visible. The film thickness may be designed so as to have high transmission characteristics for light in the wavelength band. The simulation based on the matrix method here is a method disclosed in Japanese Patent Application Laid-Open No. 2003-270725, and an angle θ is applied to a multilayer optical thin film system that is composed of a plurality of different materials and causes multiple reflection at the boundary of each layer. _When light is incident at ₀ , the phase is aligned depending on the type and wavelength of the light source to be used and the optical film thickness (product of refractive index and geometric film thickness) of each layer, and the reflected light velocity shows coherence. A simulation is performed using an equation based on a principle that causes cases to interfere with each other, and a film thickness of an optical film having desired characteristics is designed.

  In the present invention, as the specific wavelength region, the wavelength region of each of the RGB three primary colors used as image light by the projector light source is selected, and only light in these wavelength regions is reflected by a simulation based on the matrix method. The film thickness may be designed so as to transmit light in a wavelength region other than these wavelength regions. By superposing the high-refractive index film 53H and the low-refractive index film 53L having such a thickness, the optical multilayer film 53 that functions well as a three primary color wavelength band filter can be reliably realized.

  Further, the number of layers of the optical film constituting the optical multilayer film 53 formed by the dry process is not particularly limited and can be set to a desired number of layers. It is preferable that the outer layer is composed of an odd-numbered layer that is a high refractive index film 53H.

  When the optical multilayer film 53 is formed by a wet process, a high refractive index film 53H obtained by applying and curing a solvent-based paint for a high refractive index film, and an optical having a lower refractive index than the high refractive index film 53H. It is preferable to use an odd layer in which low-refractive-index films 53L obtained by applying and curing a low-refractive-index film solvent-based paint as a film are alternately laminated. Each optical film may be formed by applying a paint containing a resin that absorbs energy applied by heating, ultraviolet irradiation, or the like and causes a curing reaction. For example, the high refractive index film 53H is formed of a thermosetting resin JSR OPSTAR (JN7102, refractive index 1.68), and the low refractive index film 53L is a thermosetting resin JSR OPSTAR (JN7215, refractive index 1.41). ). Thereby, the optical multilayer film 53 has flexibility.

  Here, the high refractive index film 53H is not limited to the thermosetting resin, but is a solvent-based paint capable of ensuring a refractive index of about 1.6 to 2.1, such as the high light diffusion film. Any optical film material having a refractive index may be used. The low refractive index film 13L is not limited to the thermosetting resin, but a solvent-based paint capable of ensuring a refractive index of about 1.3 to 1.59, such as the low light diffusion film shown above. Any optical film material having a refractive index may be used. Note that the greater the difference in refractive index between the high refractive index film 53H and the low refractive index film 53L, the smaller the number of stacked layers.

  When formed by a wet process, each film thickness of the optical multilayer film 53 is, for example, highly reflective with, for example, a reflectance of 50% or more with respect to light in the three primary color wavelength regions composed of light in the wavelength regions of red, green, and blue. In addition to having the characteristics, it is designed to have a high transmission characteristic of, for example, a transmittance of 80% or more with respect to light in a wavelength band other than the three primary color wavelength band lights. Here, each film thickness of the optical multilayer film 53 is preferably designed so as to satisfy the above formula (1).

  For example, the film thickness of the high refractive index film 53H (refractive index 1.68) is 1023 nm, the film thickness of the low refractive index film 53L (refractive index 1.41) is 780 nm, the high refractive index film 53H, and the low refractive index film 53L. Nine layers are alternately stacked, and an optical multilayer film 53 having a 19-layer structure in which a high-refractive index film 53H is stacked on the stacked layers is used as a projector light (from a projector light source using the laser oscillator described above). The light has a high reflectance of 80% or more for the light of the three primary colors, and has a high transmittance of 20% or less for the wavelength light (stray light) before and after the three primary wavelengths. It can be set as the film | membrane which has.

  The absorption layer 54 is formed by applying a black paint film or a black film formed by applying a black paint to the back surface of the substrate 51B, and has a function of absorbing light. As a result, the light that has passed through the optical multilayer layer 53 is absorbed by the absorption layer 54 and reflection of the transmitted light can be prevented, and the reflection sheet 50 can more reliably obtain only light in the three primary color wavelength regions as reflected light. It becomes. Alternatively, the substrate 51B itself may function as an absorption layer by adding black paint or the like to the substrate 51B to make the color of the substrate 51B black.

  As another configuration of the reflective sheet 50, an optical multilayer film 53 having the same configuration as described above is formed on both surfaces of the substrate 51B, and an absorption layer 54 is formed on the outermost surface of one of the optical multilayer films 53. It is good.

  In the reflection sheet 50 having any configuration described above, light in a specific wavelength region (three primary color wavelength regions) corresponding to light projected from the projector light source is reflected by the light reflectance, and light other than the specific wavelength region ( External light) can be absorbed.

  Since the screen 100 includes the reflection sheet 50 to reflect light in the three primary color wavelength ranges, the observer views the reflected image of the image projected on the screen, that is, projects on the reflective screen. Only the reflected light of the recorded image 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 screen 100 is provided with the light diffusing film 10 so that the scattered reflected light from the screen 100 can be viewed. That is, with the configuration in which the light diffusion film 10 is provided on the reflection sheet 50, the light incident through the light diffusion film 10 is selectively reflected by the reflection sheet 50 in a specific wavelength region. However, at this time, the reflected light is diffused when passing through the light diffusion film 10, and scattered reflected light other than the reflective specular component can be obtained. Since the reflected specular component and the scattered reflected light exist as the reflected light from the reflective screen 100, 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.

  Further, since the screen 100 uses the light diffusing film 10 of the present invention as a light diffusing film, the surface is prevented from being damaged during peeling from the mold, during storage, and during handling. Can see the reflection image. Furthermore, when projecting image light and observing it from the front of the screen, it is possible to see a uniform, high-brightness image at a specific location, and control the reflected image light to be directed within a specific field of view. Can be confirmed. In addition, it is possible to suppress a decrease in the diffusion angle anisotropy even during long-term use by the user.

  Here, the reflection sheet 50 having a wavelength-selective reflection layer is shown, but the present invention is not limited to this, and for example, the reflectance is high over a wide wavelength range of visible light such as aluminum and silver. A reflective layer using a material may be used as long as it can reflect image light.

Next, FIG. 7 is a cross-sectional view showing the configuration of the second embodiment of the screen of the present invention.
As shown in FIG. 7, the screen 200 is a transmissive screen having a configuration in which the light diffusion film 10 is provided on the support 60.

  The support 60 is a support for the screen 200, and may be composed of a polymer such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyolefin (PO), or the like. it can.

  The screen 200 receives projection light from the surface of the support 60 opposite to the surface on which the light diffusion film 10 is provided, transmits the support 60, and scatters and radiates from the light diffusion film 10. The viewer can visually recognize a natural image by observing the scattered reflected light.

  Here, since the screen 200 uses the light diffusing film 10 of the present invention as a light diffusing film, the surface is prevented from being damaged at the time of peeling from the mold, during storage, and handling, A normal transmission image can be seen. In addition, it is possible to suppress a decrease in the diffusion angle anisotropy even during long-term use by the user.

  The screen 200 according to the present invention is produced, for example, by pasting the light diffusion film 10 on one surface of a support 60 made of a PET film.

  In addition, as a variation of the screen 200, a configuration in which the translucent resin layer 12 is formed on the support 60 may be used.

  Moreover, in any of the screens 100 and 200, it is preferable to adjust the diffusion shape by adjusting the surface shape of the light diffusion film 10 for each position of the screen, and to make the luminance distribution of the entire screen viewed from the viewer uniform. . For this purpose, for example, the axis deviation of the luminance peak may be in the direction of the center of the screen. In other words, when the diffusion characteristics of the entire screen are viewed, the brightness peak of the transmitted light is inclined toward the center of the screen as the diffusion characteristics in all the upper, lower, left and right peripheral portions of the screen. The inclination may continuously change and become larger as the position shifts from the center to the periphery.

  In addition, the application range of the light diffusion film of the present invention is not limited to the projection display device described above, and a display device and an illumination device that need to control the viewing angle, such as a backlight for a liquid crystal display. It can be applied to various fields.

  Examples of the present invention will be described below. In addition, what is shown below is an illustration and this invention is not limited to this.

Example 1
A light diffusion sheet was produced under the following conditions.
(1) Translucent resin layer replication mold:
A mold for translucent resin layer replication was produced by the sandblast method under the following conditions.
(A) Mold base material: Aluminum plate (b) Sand blasting conditions and sand blasting equipment (Fuji Seisakusho)
・ Grinding material: Alumina (count # 180, average particle size: 76 μm)
・ Distance between blast gun and mold base: 50mm
・ Angle between blast gun and mold base: 9 °
・ Compressed air pressure: 0.6 MPa
-State of spraying abrasive on the mold base surface: State of Fig. 2-Blast gun scanning condition: Scanning was performed at a pitch of 5 mm in the X direction and Y direction in the state of Fig. 3.
In addition, the uneven | corrugated shape of the surface differed in the vertical direction and the horizontal direction on the surface of the obtained mold. As a surface shape parameter, Sm (average unevenness interval) was measured using a stylus shape measuring machine ET4000A (manufactured by Kosaka Laboratory), and as an average unevenness interval Sm, S = 0.13 in the X-axis direction, S = 0.07 in the Y-axis direction.
(2) Translucent support: polyethylene terephthalate (PET) film (Nippon Magfan A4300, thickness 100 μm)
(3) Resin composition A for translucent resin layer: Mixture of ultraviolet curable acrylic resin A + sodium lauryl sulfonate 1 wt%

(Light diffusion film production procedure)
(S21) The resin composition A is applied to the fine engraving surface of the translucent resin layer replication mold.
(S22) A PET film was coated on the resin composition A coating film of the mold so that air bubbles would not enter. At this time, pressure was applied while adjusting the pressure with a rubber roller so that the thickness of the resin coating film was 50 μm.
(S23) The resin material A was cured by irradiating a cumulative irradiation amount of 1000 mJ / cm ² from the PET film side as a sufficient amount of ultraviolet light for polymerizing and curing the resin.
(S24) The mold was removed from the translucent resin layer at room temperature to obtain a light diffusion film composed of translucent resin layer / PET film.

(Examples 2 to 4)
In Example 1, the addition amount of sodium lauryl sulfonate in the resin composition A of the translucent resin layer was 3 wt% (Example 2), 4 wt% (Example 3), and 20 wt% (Example 4), respectively. A light diffusing film was produced under the same conditions as in Example 1 except for the above.

(Examples 5 and 6)
In Example 1, the surfactants in the resin composition A of the translucent resin layer were respectively sodium dodecylbenzenesulfonate 2 wt% + polyoxyethylene lauryl ether 8 wt% (Example 5), sodium dodecylbenzenesulfonate 1 wt%. % + Polyoxyethylene oleyl ether 8 wt% (Example 6), and a light diffusion film was produced under the same conditions as in Example 1 except that.

(Comparative Example 1)
In Example 1, a light diffusing film was produced under the same conditions as in Example 1 except that the surfactant in the resin composition A of the translucent resin layer was omitted (no surfactant).

(Comparative Examples 2 and 3)
In Example 1, the addition amount of sodium lauryl sulfonate in the resin composition A of the translucent resin layer was changed to 0.5 wt% (Comparative Example 2) and 30 wt% (Comparative Example 3), respectively. A light diffusion film was produced under the same conditions as in Example 1.

(Comparative Example 4)
A translucent resin layer was formed under the following conditions. The same translucent support as in Example 1 was used.
(1) Resin material I: obtained by mixing the following compositions.
・ Styrene beads (made by Sekisui Plastics, Styrene beads SBX6, particle size 6 μm) 7 wt%
UV curable acrylic resin B (resin material having a glass transition temperature different from that used in Example 1) 93 wt%

(Light diffusion film production procedure)
(S31) The resin material I is uniformly applied on the translucent support.
(S32) The resin material I was cured by irradiating ultraviolet rays with an integrated irradiation amount of 1500 mJ / cm ² without using a mold to obtain a light diffusion film composed of a translucent resin layer (bead layer) / PET film.

The following evaluation was performed about the light-diffusion film produced in this way.
(I) Measurement of surface resistance The surface resistance value was measured at 25 ° C. and 55% RH in an environmental condition using a Megaresta surface resistance meter (manufactured by SHISIDO ELECTRIC CO., LTD.).

(Ii) Pencil Hardness As an evaluation of scratch resistance, pencil hardness measurement on the light transmissive resin layer side of the light diffusion film was performed at room temperature by the method described in JIS 5600-5-4.

The evaluation results are shown in Table 1.
As a result, regarding the surface resistance values, Examples 1 to 6 and Comparative Example 3 were 1 × 10 ¹¹ Ω or less, and Comparative Examples 1, 2, and 4 were larger than 1 × 10 ¹² Ω. Moreover, regarding pencil hardness, the things other than the comparative example 3 were H or more.

(Examples A to F, Comparative examples a to d)
Next, a reflective screen was manufactured using the following optical film paint H and optical film paint L.
(1) Optical film paint H
Fine particles: TiO ₂ fine particles (Ishihara Sangyo Co., Ltd., average particle size of about 20 nm, refractive index of 2.48) 100 parts by weight (2.02 wt%)
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 (0.40 wt%)
-Binder: Mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (Nippon Kayaku Co., Ltd., UV curable resin, trade name DPHA) 30 parts by weight (0.61 wt%)
Organic solvent: methyl isobutyl ketone (MIBK) 4800 parts by weight (96.97 wt%)
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 H.
(2) Optical film paint L
・ Polyfluorobutenyl vinyl ether polymer with terminal carboxyl group (product name: Cytop, manufactured by Asahi Glass Co., Ltd.)

(3) Manufacturing method of reflection type screen (S31) The coating material H is apply | coated by the dipping method on both surfaces of a transparent support body.
(S32) The coating film of paint H is dried at 80 ° C. and then cured by ultraviolet (UV) (1000 mJ / cm ² ) to form an optical film H having a film thickness of 780 nm and a refractive index of 1.94 per side.
(S33) Next, the coating material L is applied on the optical film H having a high refractive index by a dipping method.
(S34) The coating film of the paint L is dried at 90 ° C. to form an optical film L having a thickness of 1240 nm and a refractive index of 1.34.
(S35) The coating material H is applied on the optical film L under the same conditions as in step S31.
(S36) A coating film of paint H is formed under the same conditions as in step S32, and an optical film H having a film thickness of 780 nm and a refractive index of 1.94 per side is formed. As a result, a total of six optical multilayer films were obtained on the transparent support, with three layers of optical film H / optical film L / optical film H per side.
(S37) The light diffusion sheets of Examples 1 to 6 and Comparative Examples 1 to 4 are bonded to one surface of the optical multilayer film via an adhesive layer.
(S38) A black paint was applied to the other surface of the optical multilayer film by a spray method to form a black light absorbing layer, thereby obtaining a reflective screen. Here, what used the light-diffusion film of Examples 1-6 was made into Example AF respectively, and what used the light-diffusion film of Comparative Examples 1-4 was made into Comparative Example ad, respectively.

The following evaluation was performed about the screen produced in this way.
(B) Screen gain / screen luminance distribution A white screen is projected by placing a liquid crystal projector with a light output of 2000 ANSI lumen (SONY VPL-CX5) facing from the front at a position 2 m away from the surface where the screen is pasted. The luminance S at the center of the screen was measured with a luminance meter (BM-9 manufactured by Topcon Corporation). Further, the luminance W was measured when the standard white plate was placed at the same position, and the ratio (S / W) between the luminance S and the luminance W was obtained and used as the screen gain. Further, the in-plane screen luminance distribution was visually evaluated.

(B) Diffusion angle at the time of screen production It was obtained from the state of the luminance distribution of reflected light on each screen. That is, in the measurement, a liquid crystal projector having a light output of 2000 ANSI lumen (VPL-CX5 manufactured by SONY) is placed opposite to a position 2 m away from the screen to project a white screen, and the projection lens position of the projector is set to 0 degree. Luminance measurement was performed by scanning a luminance meter (BM-9 manufactured by Topcon Corporation) on a circular arc with a radius of 2 m centering on the diffusion film. Here, the diffusion angle in the vertical direction and the horizontal direction of the screen was obtained with the angle when the luminance was half of the maximum luminance (half-value width) as the diffusion angle.

(C) Diffusion angle after standing test After the produced screen was left in a room at 25 ° C. and 50% RH for 2 weeks, the diffusion angle was determined in the same manner as in (b) above.

(D) Evaluation of dust adhesion After the produced screen was left in a room at 25 ° C. and 50% RH for 2 months, a paper wiper (size 5 cm × 5 cm) in which the screen surface (light diffusion film surface) was impregnated with 2 cc of ethanol. Wiped with. Subsequently, the wiper surface was visually observed, and those in which dust adhesion was not confirmed were evaluated as good (symbol ○), and those in which dust adhesion was confirmed were rated poor (symbol x).

The evaluation results are shown in Table 2.
For Examples A to F and Comparative Examples a to c, it was confirmed that anisotropy of the diffusion angle was imparted at the time of production. In addition, it was confirmed that the diffusion angle anisotropy was maintained in Examples A to F after the two-week standing test. On the other hand, in all of Comparative Examples a to c, the diffusion angle anisotropy was degraded.
Moreover, in Examples A to F, no dust adhesion was observed even after the two-month standing test, but in Comparative Examples a to d, dust adhesion was observed. Among these, it is thought that the comparative example c originates in the surface of a light-diffusion film being soft and sticky.
Further, in Examples A to F, it was found that a screen having a high screen gain, that is, bright and having a good in-plane luminance distribution can be obtained by appropriately controlling the horizontal / vertical diffusion angles. Furthermore, it was found that this characteristic was maintained even after a 2-week standing test.
Furthermore, in Example F, it was found that a screen having a high screen gain and a high directivity in the horizontal direction of the reflected light can be obtained.

It is sectional drawing which shows the structure of the light-diffusion film which concerns on this invention. It is the schematic which shows the state of the sandblasting with respect to the metal mold | die base material in the manufacturing method of the translucent resin layer replication metal mold | die used by this invention. It is the schematic which shows the scanning state of the blast gun in the manufacturing method of the metal mold | die for translucent resin layer trial used by this invention. It is sectional drawing which shows the structure in 1st Embodiment of the screen which concerns on this invention. It is sectional drawing which shows the optical film structure (1) of the reflective sheet. It is sectional drawing which shows the optical film structure (2) of the reflective sheet. It is sectional drawing which shows the structure in 2nd Embodiment of the screen which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mold base material, 2 ... Blast gun, 3 ... Grinding material, 10 ... Light diffusion film, 11 ... Translucent support body, 12 ... Translucent resin layer, 50 ... Reflective sheet, 51B ... Substrate, 51M ... Metal film, 52, 53 ... Optical multilayer film, 52D ... Metal oxide film, 52M ... Light absorbing thin film, 53H ... High refractive index film, 53L ... Low refractive index film, 54 ... Absorbing layer, 100, 200 ... Screen

Claims (5)

In a light diffusing film having a translucent support and a translucent resin layer having an uneven light diffusing surface on the surface provided on the translucent support, and having an anisotropic diffusion angle,
The light diffusing film, wherein the translucent resin layer has a surface resistance of 1 × 10 ¹¹ Ω or less and a pencil hardness of H or more.   The light diffusing film according to claim 1, wherein the translucent resin layer contains a surfactant in the resin.   2. The uneven shape of the light diffusing surface is obtained by transferring the shape of a mold surface formed by sandblasting so that the abrasive spraying angle is less than 90 degrees. The light diffusing film described in 1.   A screen comprising the light diffusing film according to any one of claims 1 to 3 and a reflective layer provided on a surface opposite to the light diffusing surface of the light diffusing film.   A light diffusing film according to any one of claims 1 to 3, wherein the light diffusing film transmits projection light from a surface opposite to the light diffusing surface and diffuses and radiates from the light diffusing surface. A screen characterized by that.

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