JP2008032997A - Transmission type screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission type screen capable of obtaining a wide viewing angle in both horizontal and vertical directions, and also, capable of using a conventional transmission type screen, consequently, capable of reducing the manufacturing cost. <P>SOLUTION: The transmission type screen includes: at least an optical member with a fresnel lens function; and a lenticular lens where a plurality of cylindrical lenses that are vertically long, provided that a vertical direction viewing from an observer's side is regarded as a longitudinal direction, are continuously arrayed in a horizontal direction viewing from an observer's side. An anisotropic light diffusion tacky adhesive layer is provided on the observer's side of the lenticular lens, the tacky adhesive layer is constituted of a tacky adhesive and needle fillers having the refractive index different from that of the tacky adhesive, wherein the needle filler is dispersed in the tacky adhesive while being oriented in nearly the same direction, and the long axis direction of the needle filler is nearly the same as the horizontal direction of the lenticular lens. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmissive screen to which an anisotropic diffusion medium used for rear projection is applied.

  A general rear projection includes a CRT projector or a liquid crystal projector, and a transmissive screen that projects image light emitted from the projector. The transmissive screen includes a Fresnel lens and a lenticular lens. Yes. The Fresnel lens is for deflecting the projected image light parallel to the observer side and allowing the projected image light to enter the lenticular lens perpendicularly. In addition, the lenticular lens has a configuration in which a plurality of vertically long cylindrical lenses having a vertical direction as a longitudinal direction are continuously arranged in the horizontal direction, diffracts the incident video light and diffuses the emitted light, and the horizontal viewing angle of the image It is for widening.

  Furthermore, in such rear projection, a light diffusing agent is mixed into the lenticular lens to increase the diffusion angle of the image light, or black stripes are formed on the exit surface of the lenticular lens other than the lenticular lens. There is also known a mode in which a reduction in contrast due to reflection of external light is provided.

  However, in the rear projection described above, the viewing angle in the horizontal direction is sufficiently obtained practically by the lenticular lens, but in the vertical direction, only the effect of the light diffusing agent can be obtained, so the viewing angle is narrow and the observer's When the position of the viewpoint is shifted in the vertical direction, the screen is dark, and there is a problem that an image cannot be displayed satisfactorily.

  To solve this problem, a transmission screen having a wide viewing angle in both the horizontal and vertical directions is provided by providing a light diffusion substrate in which the dispersion concentration of the light diffusion agent is varied in the thickness direction of the substrate. (For example, refer to Patent Document 1). Further, there has been reported an image display screen that can ensure a wide viewing angle in both the horizontal and vertical directions by superimposing a first lenticular screen with vertical stripes and a second lenticular screen with horizontal stripes (for example, , See Patent Document 2).

  However, these conventional screens have a problem in that the configuration including the special light diffusing plate or the second lenticular screen as described above is manufactured, which complicates the manufacturing process and increases the manufacturing cost. ing.

  In addition, as a diffusing member that diffuses light only in a specific direction, an anisotropic light diffusing adhesive layer has been developed in which acicular fillers and needle-like fillers having different refractive indexes are oriented and dispersed in substantially the same direction. (For example, refer to Patent Document 3). According to this anisotropic light diffusing adhesive layer, there is an effect that light perpendicularly incident on the anisotropic light diffusing adhesive layer is deflected in a direction perpendicular to the major axis direction of the aligned needle-like filler.

JP 2002-236319 A JP-A-2005-18070 JP 2004-221916 A

  Therefore, the present invention can obtain a wide viewing angle both in the horizontal and vertical directions, as well as a conventional transmission screen, and can reduce the manufacturing cost. It is intended to provide.

  In view of the above prior art, the present inventor applied an anisotropic light diffusing adhesive layer in which the acicular filler is oriented in substantially the same direction and dispersed in an adhesive to a conventional transmission screen, The viewing angle in the vertical direction can be enlarged, and the present invention has been completed. Therefore, the transmission type screen of the present invention includes an optical member having a Fresnel lens function and a vertically long cylindrical lens having a vertical direction as a longitudinal direction when viewed from the observer side in a horizontal direction as viewed from the observer side. In a transmission screen including at least a plurality of lenticular lenses arranged, an anisotropic light diffusion adhesive layer is provided on the viewer side of the lenticular lens, and the anisotropic light diffusion adhesive layer includes an adhesive, the adhesive, and a refractive index. The needle-like fillers are oriented in substantially the same direction and dispersed in the adhesive, and the major axis direction of the needle-like filler is substantially the horizontal direction of the lenticular lens. It is characterized by being identical.

  According to another aspect of the transmissive screen of the present invention, there is provided a transmissive screen including a first optical member having a Fresnel lens function and a second optical member having an anisotropic light diffusing adhesive layer. The two optical members are arranged closer to the observer than the first optical member, and the anisotropic light diffusion adhesive layer is composed of an adhesive and a needle-like filler having a refractive index different from that of the adhesive, and the needle-like filler Are oriented in substantially the same direction and dispersed in the pressure-sensitive adhesive, and the major axis direction of the needle-like filler is a vertical direction when viewed from the observer side.

  Furthermore, as still another aspect of the transmission screen of the present invention, a transmission type including a first optical member having a Fresnel lens function and a second optical member having first and second anisotropic light diffusion adhesive layers. The second optical member is disposed closer to the viewer than the first optical member, and the anisotropic light diffusing adhesive layer includes an adhesive and a needle-like filler having a refractive index different from that of the adhesive. The needle-shaped filler is oriented in substantially the same direction and dispersed in the pressure-sensitive adhesive, and the long axis direction of the needle-shaped filler of the first anisotropic light-diffusing adhesive layer and the second anisotropic light diffusion It is characterized in that the major axis direction of the acicular filler of the adhesive layer is different.

  Note that the vertical direction and the horizontal direction in the present invention indicate directions viewed from the observer side who observes the transmission screen.

  According to the present invention, the anisotropic light-diffusing adhesive layer in which needle-like fillers are oriented in substantially the same direction and dispersed in the adhesive is such that the major axis direction of the needle-like filler is substantially the same as the horizontal direction of the lenticular lens. As described above, by providing on the viewer side of the lenticular lens, the light emitted from the lenticular lens can be diffused in the vertical direction, and a wide viewing angle can be obtained not only in the horizontal direction but also in the vertical direction. it can.

  In addition, since the anisotropic light diffusing adhesive layer in the present invention has a function of diffusing light in a specific direction (range) as compared with a general light diffusing layer, in the configuration of the present invention, a Fresnel lens and a lenticular lens are used. By simply laminating the anisotropic light diffusing adhesive layer in the present invention on a conventional transmissive screen made of lenses in a prescribed arrangement, not only the horizontal direction but also a wide viewing angle can be obtained not only in the vertical direction. In addition, it is possible to configure the transmission screen of the present invention in which the brightness of display is not greatly reduced, and the manufacturing cost can be significantly reduced as compared with the conventional case.

  Furthermore, according to another aspect of the present invention, a second optical member having an anisotropic light diffusing adhesive layer in which needle-like fillers are oriented in substantially the same direction and dispersed in an adhesive is used. By arranging the long axis direction of the needle-like filler so as to be a vertical direction when viewed from the observer side, it is equivalent to a transmission type screen having a conventional lenticular lens, although no lenticular lens is used. The function can be exhibited, and further, with such a configuration, the thinning can be realized at a low cost.

  Further, in still another aspect of the present invention, the major axis direction of the needle-like filler of the first anisotropic light diffusion adhesive layer and the major axis direction of the needle-like filler of the second anisotropic light diffusion adhesive layer are different directions. Thus, the first and second anisotropic light diffusing adhesive layers of the second optical member are laminated. In the present invention, the major axis direction of the needle-like filler of the first anisotropic light-diffusing adhesive layer and the major axis direction of the needle-like filler of the second anisotropic light-diffusing adhesive layer are orthogonal to each other when viewed from the observer side. Preferably, the major axis direction of the needle-like filler of the first anisotropic light-diffusing adhesive layer is a vertical direction when viewed from the observer side, and the major axis of the needle-like filler of the second anisotropic light-diffusing adhesive layer More preferably, the direction is horizontal when viewed from the viewer side.

  According to such a configuration, in spite of not using a lenticular lens, as in the first aspect, the brightness of the display is not greatly reduced, and not only in the horizontal direction but also in the vertical direction. In addition, a wide viewing angle can be obtained, and further, the manufacturing cost can be reduced and the thickness can be reduced.

Next, the first aspect of the transmission screen of the present invention will be described in more detail with reference to the drawings.
As shown in FIG. 1, the transmission screen of the present invention has a configuration in which a Fresnel lens 1, a lenticular lens 2, and an anisotropic light diffusing adhesive layer 3 are provided in the order in which image light is incident. In the transmissive screen of the present invention having such a configuration, first, image light is projected onto the Fresnel lens 1 from a projector (not shown, but arranged on the right side of the drawing). The image light incident on the Fresnel lens 1 is deflected in parallel to the lenticular lens 2 disposed on the viewer side and emitted perpendicularly to the lenticular lens 2. Then, the image light incident on the lenticular lens 2 is refracted and diffused by a vertically long cylindrical lens whose longitudinal direction is the vertical direction arranged in a row in the horizontal direction, and the horizontal viewing angle of the image is enlarged. Is done.

  Next, when the image light emitted from the lenticular lens 2 is incident on the anisotropic light-diffusing adhesive layer 3, the major axis direction of the needle-like filler that is oriented and dispersed in the adhesive in substantially the same direction is the direction of the lenticular lens. Since they are arranged so as to be substantially the same as the horizontal direction, the incident video light is diffused in the vertical direction of the lenticular lens 2 and the vertical viewing angle of the image is expanded. Therefore, according to the transmissive screen of the present invention, a wide viewing angle can be obtained not only in the horizontal direction but also in the vertical direction.

  In the embodiment of the present invention shown in FIG. 1, the anisotropic light diffusing pressure-sensitive adhesive layer 3 laminated on the transparent substrate 4 is attached to the lenticular lens 2. What is necessary is just to be arrange | positioned at the observer side of the lens 2, Even if it arrange | positions a transparent base material and another optical element between an anisotropic light-diffusion adhesion layer and a lenticular lens, it replaces with a transparent base material, Other optical elements may be stacked. The other optical elements include, for example, a light reflecting element, a light diffusing element, and the like. In the case where the anisotropic light diffusing adhesive layer is sandwiched between a plurality of other optical elements, these optical elements are of the same type. It may be different or different.

  The transmission screen of the present invention is characterized by having an anisotropic light diffusing adhesive layer, and other Fresnel lenses and lenticular lenses can be made of conventionally known configurations and materials. Therefore, only the anisotropic light diffusion adhesive layer will be described below.

  The anisotropic light diffusing pressure-sensitive adhesive layer in the present invention comprises a pressure-sensitive adhesive and a needle-like filler having a refractive index different from that of the pressure-sensitive adhesive, and the needle-like filler is oriented in substantially the same direction and dispersed in the pressure-sensitive adhesive. It is essential. In the first aspect, the major axis direction of the needle filler is substantially the same as the horizontal direction of the lenticular lens. In the second aspect, the major axis direction of the needle filler is the observer. Further, in the third aspect, the major axis direction of the needle-like filler of the first anisotropic light-diffusing adhesive layer and the needle-like filler of the second anisotropic light-diffusing adhesive layer so as to be in the vertical direction when viewed from the side. It is necessary to be arranged so that the major axis direction is different. In the transmission screen of the present invention, it is sufficient that the needle-like fillers are oriented to such an extent that the anisotropic diffusion function that is the object of the present invention can be expressed, and all the needle-like fillers are not necessarily oriented correctly. You don't have to.

  Next, the anisotropic light diffusion mechanism by the anisotropic light diffusion adhesive layer in the present invention will be described in detail with reference to FIG. FIG. 2 is a diagram schematically showing the anisotropic light diffusion pressure-sensitive adhesive layer in the present invention and the diffusion state of transmitted light when thin linear light is perpendicularly incident on the anisotropic light diffusion adhesive layer. The hatched portion indicates the anisotropic light diffusion in the present invention. It is a figure which shows typically the projection image of the transmitted light of an adhesion layer. In FIG. 2, for the sake of convenience, the major axis direction of the acicular filler is taken as the x axis, the anisotropic light diffusion adhesive layer surface is taken as the xy plane, and the anisotropic light diffusion adhesive layer thickness direction is taken as the z axis.

  As shown in FIG. 2, when linear light is vertically incident on the anisotropic light diffusing adhesive layer in the present invention, the incident light is refracted on the surface of a needle-like filler having a refractive index different from that of the adhesive. As a result, the amount of light diffusion to the surface perpendicular to the major axis direction of the needle-like filler and the vicinity thereof increases, and the diffused light exhibits anisotropy. That is, the projected image of the transmitted light has an elliptical shape extending in a direction orthogonal to the major axis direction of the needle-like filler. On the other hand, in the light diffusion adhesive layer using the spherical filler instead of the acicular filler, the incident light is diffused isotropically on the surface of the spherical filler as shown in FIG. Not shown. That is, the projected image of the transmitted light has a circular shape.

  Next, the pressure-sensitive adhesive used for the anisotropic light-diffusing pressure-sensitive adhesive layer in the present invention is not particularly limited, but (a) the optical transparency is high, and (b) the group that forms the anisotropic light-diffusing pressure-sensitive adhesive layer. It has a refractive index close to that of a material (for example, a TAC film that is a protective film for a polarizing plate), (c) has a high reliability and a proven track record as an adhesive for a polarizing element, and (d) is relatively inexpensive. Those satisfying such requirements are preferable. An acrylic pressure-sensitive adhesive or the like can be cited as one that satisfies such requirements.

  The main component of the acrylic adhesive is acrylic acid and its ester, methacrylic acid and its ester, acrylamide, homopolymer of acrylic monomers such as acrylonitrile, or a copolymer thereof, at least one of the acrylic monomers, and acetic acid. Examples thereof include copolymers with vinyl monomers such as vinyl, maleic anhydride, and styrene.

  Among these, the main monomers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and the like that exhibit adhesiveness, and monomers such as vinyl acetate, acrylamide, acrylonitrile, styrene, and methacrylate, which are cohesive components, Copolymerized with functional group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, hydroxylethyl methacrylate, hydroxylpropyl methacrylate, dimethylaminoethyl methacrylate, methylolacrylamide, glycidyl methacrylate, etc. Preferred are coalesces having a glass transition point Tg in the range of −60 to −15 ° C. and a mass average molecular weight in the range of 100,000 to 2,000,000.

  In the present invention, the acrylic pressure-sensitive adhesive may contain one or more kinds of cross-linking agents such as metal chelate type, isocyanate type, and epoxy type, if necessary, in addition to the above main components.

  In addition, as an acrylic pressure-sensitive adhesive, a photopolymerization initiator or the like is blended with an oligomer having an acrylic group at the terminal or side chain and an acrylic monomer, and after coating on a substrate, it is irradiated with ultraviolet rays or the like. It is also possible to use a material in which the coating layer becomes sticky.

  Further, the acrylic pressure-sensitive adhesive is preferably free from fogging and coloring and highly transparent, and its refractive index is preferably 1.45 to 1.55. In addition, in this specification, the refractive index of the adhesion layer shall be measured based on A method as described in JIS K-7142 (1996).

  Moreover, in the anisotropic light-diffusion adhesive layer in this invention, adhesive force is adjusted so that the 180 degree peeling strength based on JIS-Z-0237 (1980) may be in the range of 100-2000g / 25mm. Is practically preferable. If the 180 ° peel strength is less than 100 g / 25 mm, the environmental resistance is insufficient, and peeling may occur particularly at high temperatures and high humidity. On the other hand, if it exceeds 2000 g / 25 mm, it is difficult to reattach and can be reattached. Is also not preferable because an adhesive may remain in the peeled portion.

  The needle-like filler used in the present invention is not particularly limited as long as it is a high aspect ratio filler that has a refractive index different from that of the pressure-sensitive adhesive and exhibits a needle shape (including a fiber shape). A colorless or white one is preferred. Specifically, metal oxides such as titanium oxide, zirconium oxide and zinc oxide, boehmite, aluminum borate, calcium silicate, basic magnesium sulfate, calcium carbonate, potassium titanate and other metal compounds, glass, synthetic resin, etc. A needle-like or fibrous material made of is preferably used.

  As the size of the acicular filler, the major axis is preferably 2 to 5000 μm and the minor axis is preferably 0.1 to 20 μm, and the major axis is particularly preferably 10 to 300 μm and the minor axis is 0.3 to 5 μm. If the major axis is less than 2 μm or more than 5000 μm, it is difficult to satisfactorily disperse and orient the needle filler in the adhesive layer, and the anisotropic light diffusion function may not be stably exhibited. On the other hand, if the minor axis is less than 0.1 μm, it is difficult to disperse and orient the needle-shaped filler well, and the light diffusing function may be deteriorated. If the minor axis exceeds 20 μm, the diffused light is glaring. Since it becomes strong, it is not preferable.

  In the present invention, it is essential that there is a difference in refractive index between the pressure-sensitive adhesive and the needle-like filler, but in order to develop a good light diffusion function, the difference in refractive index may be 0.01 or more. Preferably, it is 0.05 or more. In addition, the refractive index of the acicular filler in this specification shall be measured based on the B method as described in JIS K-7142 (1996).

  The content of the acicular filler in the anisotropic light diffusing adhesive layer in the present invention is not particularly limited, but the desired optical characteristics, the size and specific gravity of the acicular filler, the refractive index of the adhesive and the acicular filler It is suitably designed according to a difference etc., it is preferable that it is 0.1-50.0 mass%, and it is especially preferable that it is 5-45 mass%. If the content of the acicular filler is less than 0.1% by mass, the light diffusibility may be insufficient, and if it exceeds 50.0% by mass, the adhesive force may be reduced to cause peeling, which is not preferable.

  Although the thickness of the anisotropic light-diffusion adhesive layer in this invention is not specifically limited, It is preferable that it is 1-50 micrometers, and it is especially preferable that it is 10-30 micrometers. If the thickness of the anisotropic light diffusing adhesive layer is less than 1 μm, there is a possibility that sufficient adhesive force and anisotropic light diffusing function cannot be expressed. If the thickness exceeds 50 μm, further improvement in optical properties cannot be obtained, and the production efficiency also deteriorates. Therefore, it is not preferable.

Subsequently, the manufacturing method of the anisotropic light-diffusion adhesive layer in this invention is demonstrated.
The anisotropic light diffusing pressure-sensitive adhesive layer in the present invention is prepared, for example, by preparing a filler-containing pressure-sensitive adhesive composition in which needle-like fillers are dispersed in a pressure-sensitive adhesive, and coating this on a substrate such as a release sheet or various optical elements. After that, the solvent is removed by drying, and a release sheet and various optical elements are laminated thereon, and if necessary, in order to cure or stabilize the adhesive component, at room temperature or in a temperature environment of about 30 to 60 ° C. And can be easily manufactured by curing for about 1 day to 2 weeks.

  In general, an adhesive such as an acrylic adhesive is commercially available in a state containing a solvent such as ethyl acetate, acetone, methyl ethyl ketone, and toluene, but in preparing a filler-containing adhesive composition, wettability, leveling property, In order to improve coating suitability such as drying property, a solvent such as butyl acetate, methyl isobutyl ketone, and cyclohexanone may be added as necessary in addition to the above solvent.

  In addition, in order to improve the dispersibility of the acicular filler in the adhesive, the filler surface is modified by previously acting a dispersibility improver such as fats and oils, surfactants, and silane coupling agents on the filler surface. You may keep it. In addition, this dispersibility improvement agent can also be mix | blended with a filler containing adhesive composition instead of making it adhere to the surface of an acicular filler. The dispersion of the needle-like filler into the adhesive can be performed using various mixing / stirring devices such as a disperser, an agitator, a ball mill, and an attritor, and a dispersing device. Moreover, a coloring dye, fluorescent dye, a thickener, surfactant, a leveling agent, etc. can also be added to a filler containing adhesive composition as needed.

  The prepared filler-containing pressure-sensitive adhesive composition is preferably defoamed in advance before being applied to the substrate. The filler-containing adhesive composition can be applied using a coater such as a reverse coater, a dam coater, a comma coater, a die coater, a doctor bar coater, a gravure coater, a micro gravure coater, or a roll coater.

  When applying the filler-containing pressure-sensitive adhesive composition, each needle-like filler is oriented so that its major axis is substantially along the coating direction due to the shearing force applied to the filler-containing pressure-sensitive adhesive composition. The anisotropic light-diffusing adhesive layer in the present invention that is oriented and dispersed in the same direction can be produced relatively easily. The degree of orientation of the needle filler can be adjusted by the size of the needle filler, the viscosity of the filler-containing adhesive composition, the coating method, the coating speed, and the like. Moreover, the thickness of the anisotropic light-diffusion adhesive layer to form can be easily adjusted with the coating thickness of a filler containing adhesive composition, the amount of solvents in a filler containing adhesive composition, etc.

It is a figure which shows typically the transmissive screen of this invention. It is a figure which shows typically the diffused state of the transmitted light when thin linear light makes normal incidence on the anisotropic light-diffusion adhesive layer in this invention. It is a figure which shows typically the diffused state of the transmitted light when thin linear light makes perpendicular incidence to the light-diffusion adhesive layer using a spherical filler.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fresnel lens, 2 ... Lenticular lens, 3 ... An anisotropic light-diffusion adhesive layer,
4 ... Transparent substrate.

Claims (7)

An optical member having a Fresnel lens function and at least a lenticular lens in which a plurality of vertically long cylindrical lenses whose longitudinal direction is the vertical direction when viewed from the observer side are continuously arranged in the horizontal direction when viewed from the observer side are provided. In transmissive screens,
On the viewer side of the lenticular lens, an anisotropic light diffusion adhesive layer is provided,
The anisotropic light diffusing pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive and a needle-like filler having a refractive index different from that of the pressure-sensitive adhesive,
The needle-like filler is oriented in substantially the same direction and dispersed in the pressure-sensitive adhesive,
The transmission type screen, wherein a major axis direction of the needle filler is substantially the same as a horizontal direction of the lenticular lens. A transmissive screen comprising a first optical member having a Fresnel lens function and a second optical member having an anisotropic light-diffusing adhesive layer,
The second optical member is disposed closer to the observer than the first optical member,
The anisotropic light diffusing pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive and a needle-like filler having a refractive index different from that of the pressure-sensitive adhesive,
The needle-like filler is oriented in substantially the same direction and dispersed in the pressure-sensitive adhesive,
A transmission type screen, wherein a major axis direction of the needle-like filler is a vertical direction when viewed from the observer side. A transmissive screen comprising a first optical member having a Fresnel lens function and a second optical member having first and second anisotropic light diffusing adhesive layers,
The second optical member is disposed closer to the observer than the first optical member,
The anisotropic light diffusing pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive and a needle-like filler having a refractive index different from that of the pressure-sensitive adhesive,
The needle-like filler is oriented in substantially the same direction and dispersed in the pressure-sensitive adhesive,
A transmission type screen, wherein the major axis direction of the needle-like filler of the first anisotropic light-diffusing adhesive layer is different from the major axis direction of the needle-like filler of the second anisotropic light-diffusing adhesive layer.   The major axis direction of the needle-like filler of the first anisotropic light-diffusing adhesive layer and the major axis direction of the needle-like filler of the second anisotropic light-diffusing adhesive layer are perpendicular to each other when viewed from the observer side. The transmissive screen according to claim 3.   The major axis direction of the needle-shaped filler of the first anisotropic light-diffusing adhesive layer is a vertical direction when viewed from the observer side, and the major axis direction of the needle-shaped filler of the second anisotropic light-diffusing adhesive layer is the observer side The transmissive screen according to claim 3, wherein the transmissive screen is in a horizontal direction when viewed from above.   The transmission type screen according to any one of claims 1 to 5, wherein the needle-like filler has a major axis of 2 to 5000 µm and a minor axis of 0.1 to 20 µm.   The transmission type screen according to any one of claims 1 to 5, wherein a difference in refractive index between the pressure-sensitive adhesive and the needle-like filler is 0.01 or more.

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