JP2007011255A - Lens array sheet, transmission type screen, and rear projection television - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens array sheet by which white scattering is controlled while reducing the absorption of light and reducing the lowering of a gain, and to provide a transmission type screen used for a rear projection television. <P>SOLUTION: Regarding the lens array sheet, the transmission type screen and the rear projection television, the lens array sheet is equipped with a lens array layer having an integrally formed lens layer where a first lens array and a second lens array each having a plurality of semi-columnar cylindrical lenses arranged in parallel are arranged on the same plane so that the length directions of the cylindrical lenses may cross each other, and the cross section of the second lens array has a combined shape so that an arc as a part of an aspherical surface may be formed to a nearly V-shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens array sheet used for a rear projection display such as a liquid crystal projection television and a display, and a transmissive screen using the same.

  FIG. 4 shows an example of the configuration of a conventional transmissive screen used for a liquid crystal projection television or the like. Reference numeral 1 in the drawing denotes a Fresnel lens, and this Fresnel lens 1 is configured by providing a lens layer 1b having concentric irregularities formed on one surface of a plate-like base material layer 1a. Generally, in a liquid crystal projection television, the projector is disposed on the base material layer 1a side.

  A lenticular sheet 2 is provided in parallel at a predetermined interval on the lens layer 1 b side of the Fresnel lens 1, and a transmission screen composed of the Fresnel lens 1 and the lenticular sheet 2 is configured. This lenticular sheet 2 is roughly composed of a lenticular layer 3, a photosensitive resin layer 5, a light shielding layer 6, an adhesive layer 7, and a diffusion layer 8 that are sequentially laminated, and the lenticular layer 3 is disposed on the Fresnel lens 1 side. Then, the diffusion layer 8 is disposed on the viewer side. A hard coat layer 9 is provided on the viewer-side surface of the diffusion layer 8 as necessary for surface protection.

  The lenticular layer 3 is composed of a plate-like base material layer 3a and a lens layer 3b provided on one side thereof. The lens layer 3b is configured by, for example, arranging a plurality of semi-cylindrical cylindrical lenses 4 so that their length directions are parallel to each other, and the cylindrical surface 4a is disposed on the Fresnel lens 1 side.

  Hereinafter, the configuration of the lenticular sheet 2 will be described following the manufacturing operation. First, the photosensitive resin layer 5 is applied to the surface of the lenticular layer 3 on the base material layer 3a side. The photosensitive resin layer 5 is tacky in an unexposed state, and has a characteristic that it is denatured by exposure and almost loses tackiness. Then, when light is irradiated from the lens layer 3 b side through the Fresnel lens 1 in the same manner as when actually used as a transmission type screen, the stripe-shaped light beam condensed through the lenticular layer 3 is applied to the photosensitive resin layer 5. Irradiated. Then, the exposed portion of the photosensitive resin layer 5 is denatured and the tackiness is lost. Then, when a transfer film having a black transfer layer containing black carbon or the like is pressed against the photosensitive resin layer 5, the transfer layer is selectively transferred to an unexposed portion having adhesiveness, and a plurality of black lines are formed. Parallel stripe-shaped light shielding layers 6 are formed. In other words, the light-shielding layer 6 shields the part that does not transmit light.

  Then, the lenticular sheet 2 is obtained by laminating the film-like pressure-sensitive adhesive layer 7 and further laminating the plate-like diffusion layer 8 and firmly integrating them. The diffusion layer 8 is formed by mixing a diffusion material made of a plurality of glass beads in a matrix made of, for example, an acrylic plastic. Then, if necessary, the hard cord layer 9 is laminated on the surface of the diffusion layer 8 and integrated.

Then, when this transmissive screen is attached to a liquid crystal projector equipped with a projector as shown in FIG. 5 and light is emitted from the projector, this light becomes a substantially parallel light via the Fresnel lens 1. Then, a predetermined light distribution angle is imparted by transmitting the light rays through the lenticular layer 3, and the light is appropriately spread in the left-right direction (horizontal direction) of the screen, and the viewing angle in this direction is controlled. The light beam that has passed through the lenticular layer 3 becomes a striped light beam that is parallel to the length direction of the cylindrical lens, and further passes through the light shielding layer 6 and then in the vertical direction (vertical direction) of the screen by the action of the diffusion layer 8. The light beam diffuses moderately, and the viewing angle in this direction is controlled. The light shielding layer 6 can improve the S / N ratio and provide an image with good contrast.

  Further, all of the transmissive screens proposed in Patent Documents 1 to 4 are common in that a lenticular lens including an aspherical surface is used in a horizontal / vertical lens array structure.

Patent documents are described below.
JP 2002-174703 A JP 2003-167298 A JP 2004-246352 A JP 2005-37761 A

  As described above, the conventional lenticular sheet and transmissive screen use a combination of a lenticular layer and a diffusion layer in order to control the viewing angle in the horizontal and vertical directions of the screen. However, the diffusion layer has a problem that the gain decreases due to light absorption and the S / N ratio decreases due to an increase in white scattering.

  In addition, when two lenticular layers are laminated and used so that the length directions of the respective cylindrical lenses are orthogonal to each other, or when a plurality of cylindrical lenses are arranged on both surfaces of a single base material layer, the respective cylindrical lenses are used. Although the method of controlling the viewing angle in the horizontal direction and the vertical direction by providing the length directions of the lens in a direction orthogonal to each other is also conceivable, the material constituting the cylindrical lens is substantially doubled, and the fine lens Since processing needs to be performed twice, there is a problem that costs for materials, processing, and the like increase.

  Furthermore, a method of densely arranging a plurality of individual independent lenses and prisms capable of providing light distribution angles in both the vertical direction and the horizontal direction on one side of the base material layer, as in a microlens array. Although it can be considered, complicated processing is required, and it is difficult to expand and miniaturize the area, and the productivity is also low, so an increase in cost is unavoidable.

  In addition, the first lens array in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel and the second lens array arranged on the same plane so that the length directions are orthogonal to each other are integrated. In the lens sheet to be manufactured, the productivity of the mold and the productivity of the lens sheet are inferior due to the aspect ratio of the lens and the discontinuous shape. Further, since the lens shape is also matched with respect to the optical characteristics, the determination of the viewing angle characteristics in the vertical direction and the horizontal direction is a great design limitation as well as the above-described moldability.

  Furthermore, the lens / prism pitch of the first lens array and the second lens array is important. That is, when the pitch of the second lens array is different from the pitch of the first lens array, moire in the vertical direction that is not assumed in the conventional lenticular method occurs. These factors are considered separately at the time of design, and it is not desirable because they must be fully studied from the viewpoint of moire in addition to optical characteristics.

The present invention has been made in view of the above problems, and provides a transmissive screen for use in a lens array sheet and a rear projection television that can suppress white light scattering with little light absorption, low gain reduction, and the like. The issue is to provide. Furthermore, it is an object of the present invention to provide a transmission screen with low material costs, processing costs, and the like by improving the processing difficulty.

In order to solve the above problems, the present invention
The invention according to claim 1
A first lens array and a second lens array in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel are arranged on the same plane so that the length directions of the cylindrical lenses are orthogonal to each other. The second lens array has a lens array layer having a segmented lens layer, and the cross-sectional shape of the second lens array is a shape obtained by combining arcs that are part of an aspherical shape so as to be substantially V-shaped. It is a lens array sheet.

The invention according to claim 2
2. The lens array sheet according to claim 1, further comprising a light-shielding layer having an opening through which a light beam refracted / transmitted through the lens array sheet is provided in the vicinity of the imaging surface of the first lens array layer. It is a lens array sheet as described in above.

The invention according to claim 3
3. The lens array sheet according to claim 1, wherein the lens array sheet has a flat portion of 1 μm or less in the vicinity of the vertex of each lens of the second lens array.

The invention according to claim 4
4. The lens array sheet according to claim 1, wherein a cross-section of the cylindrical lens constituting the first lens array is an aspherical shape. 5.

The invention according to claim 5
The lens array sheet according to any one of claims 1 to 4, wherein the lens array layer comprises a base material layer and a lens layer provided on one surface thereof, and the lens layer comprises a radiation curable resin. It is a lens array sheet characterized by these.

The invention according to claim 6
The lens array sheet according to any one of claims 1 to 5, wherein the lens array layer includes at least a base material layer, a lens layer provided on one surface thereof, and a light shielding layer, The lens array sheet is characterized in that the pattern is a combination of linear pattern openings arranged in a row and a ladder-like short linear pattern opening therebetween.

The invention according to claim 7 provides:
A transmissive screen comprising the lens array sheet according to any one of claims 1 to 6 and a Fresnel lens.

The invention according to claim 8 provides:
The transmissive screen according to claim 7, wherein the Fresnel lens includes a base material layer and a lens layer provided on one surface thereof, and the lens layer includes a radiation curable resin.

The invention according to claim 9 is:
A rear projection television using the transmission screen according to claim 7 or 8.

  As described above, in the invention according to the first aspect of the present invention, it is possible to control the light distribution characteristics (viewing angles) in both the vertical direction and the horizontal direction with respect to the light rays transmitted through the lens array layer. Therefore, material costs and processing costs can be reduced compared to the case of using two lens array layers or forming lens layers on both sides of the base material layer. Further, the diffusion layer can be omitted or simplified to reduce light absorption and gain reduction in the diffusion layer. As a result, the white scattering phenomenon caused by the diffusion layer can be suppressed and a high S / N ratio can be realized. Also, by combining the arcs that are part of the aspherical shape so as to be substantially V-shaped, it is possible to achieve both light condensing on the light shielding layer and appropriate light distribution characteristics, and a screen with excellent contrast and light distribution characteristics. In addition, the cross-sectional shape can be changed gradually, and the workability can be improved.

  In the invention which concerns on Claim 2, by providing a light shielding layer, S / N ratio can be improved further and an image with favorable contrast can be provided.

  In the invention according to claim 3, by having a flat portion of 1 μm or less near the apex of the individual element prisms of the second lens array, the mold and the lens sheet can be economically maintained while maintaining the performance of the screen. Can be produced economically.

  In the invention according to claim 4, since the cross-sectional shape of the cylindrical lens is an aspherical shape, the aberration at the time of image formation can be reduced, and the light incident on the light shielding layer opening can be refined.

  In the invention which concerns on Claim 5, since the lens layer of a lens array layer consists of radiation curable resin, a fine pitch process can be given.

  In the invention which concerns on Claim 6, the largest S / N improvement effect can be acquired by adapting the pattern of a light shielding layer to a lens shape.

  In the invention which concerns on Claim 7, the transmission type screen provided with the above-mentioned effect can be provided combining the lens array sheet and Fresnel lens as described in any one of Claims 1-4.

  In the invention according to claim 8, since the lens layer of the Fresnel lens is made of radiation curable resin, fine pitch processing can be performed.

  FIG. 1 is a view showing a lens array layer constituting an example of a lens array sheet of the present invention. The main feature of this lens array sheet is the shape of the lens array layer. This lens array layer is constituted by a lens layer provided on one surface of a plate-like base material layer.

  The lens layer is a first lens array in which cylindrical surfaces are arranged in parallel in the length direction, and a V having a flat portion of 1 μm arranged in the length direction in parallel. The second lens array includes a prism array having a cross-sectional shape.

  The first lens array has a function of diffusing light rays in the horizontal direction and has a shape corresponding to the H-direction cross section 13. The second lens array has a function of diffusing light rays in the vertical direction and has a shape corresponding to the V-direction cross section 12. Since the light distribution characteristic of the rear projection screen is generally set such that the horizontal light distribution characteristic is wider than the vertical light distribution characteristic, the V-side cross section has a shallower shape than the H-side cross section due to the difference in lens shape. Become.

  The intersecting portion where the first lens array and the second lens array intersect with each other has a shape in which the first lens array and the second lens array intersect with each other. However, since the second lens array has a low aspect ratio, the occlusion is shallow. Although the fitting part 19 in FIG. 4 corresponds, the light diffusion effect in the horizontal direction of the first lens array is reduced by the fitting of this part. Therefore, it is desirable to determine the lens shape in consideration of that amount. Of course, it has an integral structure, and the lens array layer is composed of one member.

  FIG. 2 shows a cross-sectional view in the V direction. The first lens array and the second lens array are arranged and integrated on the same plane (one surface of the base material layer) so that the length directions are orthogonal to each other, thereby constituting one lens layer. The shape of the lens formed by the lens array layer 14 is the second lens array shape, which is a substantially V shape obtained by superimposing two aspherical arcs, with an emphasis on light distribution in the vertical direction from the front. With structure. The light refracted by the lens array layer 14 passes through the base material layer 15, passes through the photosensitive resin layer 16, passes through the opening of the light shielding layer provided on the exit side of the tourism resin layer 16, and emits light on the vertical side. 17 is emitted to the observer side.

  FIG. 3 shows a cross-sectional view in the H direction. In the H direction, the lens array layer 14 has a first lens array shape and a cylindrical cross section. The cross-sectional shape is not a perfect semicircular shape (spherical lens), but a known so-called non-circular shape (so-called secondary aspherical shape) such as a semi-elliptical shape (elliptical lens) or a parabolic shape (parabolic lens). Further, a high-order aspherical shape having a second-order term and the like can be used. When an aspherical lens is used in this way, aberration during image formation can be reduced, and incident light can be refined.

  The light rays further spread by the diffusion layer provided thereafter reach the observer as image light, and the image can be viewed.

  The material of the lens array layer 14 is a transparent material such as glass or plastic, and any material used for an optical member can be used without particular limitation. In view of production efficiency, it is preferable to use plastic. Examples of plastics include acrylic resins such as polymethyl methacrylate, polycarbonates, acrylic-styrene copolymers, styrene resins, and polyvinyl chloride. In addition, since fine fine pitch processing can be performed, it is preferable to use a radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin as a material for the lens layer.

  As the radiation curable resin, for example, a composition in which a reaction diluent, a photopolymerization initiator, a photosensitizer, or the like is added to urethane (meth) acrylate and / or epoxy (meth) acrylate oligomer can be used. The urethane (meth) acrylate oligomer is not particularly limited, and examples thereof include polyols such as ethylene glycol, 1,4 butanediol, neopentyl glycol, polycaprolactone polyol, polyester polyol, polycarbonate diol, and polytetramethylene glycol. , Hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylene isocyanate, and other polyisocyanates. The epoxy (meth) acrylate oligomer is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, terminal glycidyl ether of bisphenol A type propylene oxide adduct, fluorene epoxy It can be obtained by reacting an epoxy resin such as a resin with (meth) acrylic acid.

The lens array layer can be manufactured, for example, as follows. That is, preferably, a radiation curable resin is applied in an uncured state on a base material layer made of a plastic such as polyethylene terephthalate, polycarbonate, or polyvinyl chloride, and a molding stamper is pressed onto the surface of the base layer to be embossed. The lens layer is formed by irradiating with predetermined radiation and curing.

  The molding stamper can be manufactured, for example, as follows. That is, in the manufacture of a conventional molding stamper for a lenticular, for example, a cutting tool having a circular cutting edge is used on the surface of a cylindrical cylinder made of copper or the like. Make cuts along the direction. When a plurality of the cuts are formed in parallel, a lenticular stamper can be obtained. Furthermore, if a plurality of cuts are formed in parallel in the direction orthogonal to the circumferential cut, a molding stamper used for manufacturing the lens array layer of the present invention can be obtained. Therefore, the molding stamper for manufacturing the lens array layer of the present invention can be easily manufactured using conventional techniques, and the productivity is good. As described above, the lens array layer can be manufactured by a method similar to a method conventionally used for manufacturing a lenticular.

  Further, as shown in FIG. 1, a photosensitive resin layer is provided on the other surface (image forming surface side) of the base material layer, and a light shielding layer is further provided. The photosensitive resin layer 15 and the light shielding layer are manufactured as follows. As an example of the pattern exposure process, as shown in FIG. 4, the Fresnel lens 1 is arranged in parallel in the same manner as in a state where it is actually used as a transmissive screen, and the lens layer 13 b side through this Fresnel lens 1. When the light beam is irradiated, the photosensitive resin layer in the portion exposed through the lens array layer is denatured as shown in FIG. 1, and the tackiness is lost. Then, by pressing a transfer film provided with a black transfer layer containing black carbon or the like on this photosensitive resin layer, the transfer layer is selectively transferred to an unexposed portion having adhesiveness, and a light shielding layer is formed. The

  In this case, the first image pattern in the form of stripes formed by condensing the light beam by the first lens array (cylindrical lens) and the first image pattern formed by substantially condensing the light beam by the second lens array. A grid-like imaging pattern is formed from the stripe-shaped second substantially imaging pattern orthogonal to the imaging pattern. In other words, both the vertical and horizontal viewing angles of the light beam irradiated from the lens layer side are controlled by the first and second lens arrays at a time. The light shielding layer is provided to shield a portion through which light does not transmit. Therefore, according to this imaging pattern, a plurality of substantially square light-shielding portions are arranged at predetermined intervals in the vertical and horizontal directions, respectively.

  A lens array sheet can be obtained by providing an adhesive layer, a diffusion layer, a hard code layer, and the like on the light shielding layer as necessary. As described above, in this lens array sheet, the light distribution characteristics (viewing angles) in both the vertical direction and the horizontal direction are controlled by the first lens array and the second lens array with respect to the light rays transmitted through the lens array layer. be able to. Therefore, material costs and processing costs can be reduced compared to the case of using two lens array layers or forming lens layers on both sides of the base material layer. Further, the diffusion layer can be omitted or simplified to reduce light absorption and gain reduction in the diffusion layer. As a result, the white scattering phenomenon caused by the diffusion layer can be suppressed and a high S / N ratio can be realized. In addition, when it is set as the structure which does not provide a diffusion layer, it is preferable to provide a hard-code layer directly on a light shielding layer and to make a lens array sheet. In addition, the thickness of each layer of the lens array sheet of the present invention, the pitch of the lens layers, and the like are not particularly limited, and can be appropriately changed according to the application.

As shown in FIG. 5, the transmissive screen can be configured by arranging the lens array sheet of the present invention instead of the lenticular sheet and further arranging the Fresnel lens in parallel. The configuration of the Fresnel lens is not particularly limited, and known ones can be used, but since fine processing is possible and fine pitch ones can be obtained, plastics such as polyethylene terephthalate, polycarbonate, polyvinyl chloride, etc. A radiation curable resin is applied in an uncured state on a base material layer made of the above, and a molding stamper is pressed onto the base material layer to be embossed, and is cured by irradiating with predetermined radiation. Those formed are preferred.

  Hereinafter, an example is shown and the effect of the present invention is explained.

The lens array sheet shown in FIGS. 1 to 3 is a shape diagram created based on the lens shape design. In this example, design parameters were determined as follows.
(Design parameters)
(1) In the base material layer of the lens array layer, the material was polyethylene terephthalate, and the thickness was 75 μm.
(2) In the lens layer of the lens array layer, the material is UV photosensitive resin, and the lens shape is an aspherical shape with a pitch of 98 μm, an elliptical surface as a reference surface, and correction by higher order terms.
(3) For the photosensitive resin layer, a 20 μm thick chromin film (trade name: manufactured by DuPont) was used.

Further, as described above, in the conventional lenticular sheet, the viewing angle only in the horizontal direction can be given by the lenticular lens, and the viewing angle in the vertical direction cannot be given. In this embodiment, since the viewing angle can be given by the lens in the vertical direction as well, it is easy to obtain the same effect as the conventional one even if the amount of the diffusing material used in the diffusion layer is reduced as compared with the conventional one.
Even when the lens sheet is molded, the second lenticular lens portion of the mold may be open at an obtuse angle, and a moldability equivalent to that of a conventional lenticular lens can be obtained. In addition, by attaching a flat surface (thread surface) of about 1μ to the prism-shaped top portion of the second lens array portion, the durability and cutting performance of the die cutting tool are improved, and a stable die is obtained. In addition, even when the lens sheet is molded, it is possible to prevent the “plate removal phenomenon” in which the resin remains on the lens plate.

  Further, when the thickness of the substrate layer of the lens array layer is 188 μm, the thickness of the substrate layer is 200 to 180 μm, and when the thickness of the substrate layer is 100 μm, the lens pitch is 160 to 140 μm. When the thickness is 75 μm, good results can be obtained with a lens pitch of 115 to 75 μm, and when the thickness of the base layer is 50 μm, a lens pitch of 100 to 60 μm. It was confirmed that there was a range of selection.

It is the figure which showed the lens array layer which comprises an example of the lens array sheet of this invention. It is a V direction sectional view in an example of a lens array sheet of the present invention. It is a H direction sectional view in an example of a lens array sheet of the present invention. It is the schematic block diagram which showed an example of the conventional transmissive screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fresnel lens 1a ... Base material layer 1b ... Lens layer 2 ... Lenticular sheet 3 ... Lenticular layer 3a ... Base material layer 3b ... Lens layer 4 ... Cylindrical lens 4a ... Cylindrical surface 5 ... Photosensitive resin layer 6 ... Light shielding layer 7 ... Adhesive layer 8 Diffusion layer 9 Hard coat layer 11 Top view of the lens sheet of the present invention 12 V direction cross section 13 H direction cross section 14 Lens array layer 15 Base material layer 16 Photosensitive resin layer 17 Vertical emission light 18 ... Horizontal emission light 19 ... Fitting part

Claims (9)

  A first lens array and a second lens array in which a plurality of semi-cylindrical cylindrical lenses are arranged in parallel are arranged on the same plane so that the length directions of the cylindrical lenses are orthogonal to each other, and are integrated. The second lens array has a lens array layer having a structured lens layer, and a cross-sectional shape of the second lens array is a combination of arcs that are part of an aspherical shape so as to be substantially V-shaped. Lens array sheet.   2. The lens array sheet according to claim 1, further comprising a light-shielding layer having an opening through which a light beam refracted / transmitted through the lens array sheet is provided in the vicinity of the imaging surface of the first lens array layer. The lens array sheet according to 1.   3. The lens array sheet according to claim 1, wherein the lens array sheet has a flat portion of 1 μm or less in the vicinity of the vertex of each lens of the second lens array.   The lens array sheet according to any one of claims 1 to 3, wherein a cross-section of the cylindrical lens constituting the first lens array is an aspherical shape.   The lens array sheet according to any one of claims 1 to 4, wherein the lens array layer includes at least a base material layer and a lens layer provided on one surface thereof, and the lens layer is made of a radiation curable resin. A lens array sheet.   The lens array sheet according to any one of claims 1 to 5, wherein the lens array layer includes at least a base material layer, a lens layer provided on one surface thereof, and a light shielding layer, A lens array sheet characterized in that the pattern is a combination of linear pattern openings arranged in a row and a short ladder-shaped linear pattern opening between them.   A transmissive screen comprising the lens array sheet according to any one of claims 1 to 6 and a Fresnel lens.   The transmissive screen according to claim 7, wherein the Fresnel lens includes a base material layer and a lens layer provided on one surface thereof, and the lens layer includes a radiation curable resin.   A rear projection television using the transmission screen according to claim 7 or 8.