JP2008070441A - Optical sheet and manufacturing method of optical sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet which can take a large diffusion angle in any direction and can be easily reused. <P>SOLUTION: The optical sheet 10 is equipped with a lenticular lens layer 11, and a light shielding layer 15 from a light incident side. The lenticular lens layer has a light incident side lenticular lens part 12 where a plurality of lenticular lenses 12a, 12a are arranged in parallel on one surface of a base sheet 14 and a light emitting side lenticular lens part 13 where a plurality of lenticular lenses 13a, 13a are arranged in parallel on the other surface of the base sheet in a direction perpendicular to the light incident side lenticular lens. The light shielding layer has: light shielding parts 16, 16 on a light emitting side surface of the light emitting side lenticular lens part; and transmission openings 17, 17 provided near a focal position of the lenticular lens of the light incident side lenticular lens part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical sheet having a lenticular lens applied to a transmissive screen such as a rear projection television, and a method for manufacturing the same.

  The rear projection television is a device that provides an appropriate image to an observer by controlling image light from a projector with a screen. FIG. 8 schematically shows the internal configuration of the rear projection television 100. The right side of the page is the observer side. Further, in FIG. 8, the path of the image light from the time when the image light projected from the projector 102 is projected to the viewer side via the screen 104 is illustrated by a one-dot chain line arrow.

  The rear projection television 100 includes a projector 102 that projects image light and a reflecting mirror 103 that reflects the image light from the projector 102 toward the viewer inside the housing 101. It mainly includes a screen 104 that appropriately distributes and transmits light as an image.

  The screen 104 is arranged on the light source side to restrict the image light from the projector 102 to a predetermined range, and the image light arranged on the observer side and transmitted through the Fresnel lens sheet to appropriately control the observer. An optical sheet is provided.

  As described above, the optical sheet controls the image light from the Fresnel lens sheet to provide appropriate image light to the observer, but also has a function of blocking outside light. Therefore, as one example of the optical sheet, a microlens sheet in which a plurality of microlenses (convex three-dimensional lenses) are arranged on the light incident side, and a microlens sheet are stacked on the viewer side of the microlens sheet. Some include a light shielding layer having a transmission opening at a focal position. According to this, the image light entering the microlens is focused in the vicinity of the transmission aperture of the light shielding layer. On the observer side of the focal point, the image light diffuses in any of horizontal, vertical, and diagonal directions therebetween. Therefore, the viewer can appropriately observe the image from any position. Furthermore, since the outside light is absorbed by the portion other than the transmission opening of the light shielding layer and the influence of the outside light on the image light can be suppressed, the contrast can be improved.

  However, with the recent increase in the precision and density of optical sheets, the microlenses have become more difficult to manufacture, and there has been a demand for optical sheets that can be easily manufactured.

  On the other hand, there is an optical sheet using a lenticular lens that is a convex two-dimensional lens. In this method, a plurality of lenticular lenses are arranged in parallel on the light incident side, and a light shielding layer having a transmissive aperture is provided in the vicinity of the focal position. As a result, the manufacture of the optical sheet is easier than that having a microlens. However, since the lenticular lens is a two-dimensional lens, light can be diffused only in one direction such as the horizontal direction or the vertical direction. It was necessary to laminate a layer having a light diffusing agent (light diffusing layer) on the side surface. The light diffusing layer can diffuse light, but stray light is generated at the same time. Therefore, provision of a transient diffusing function sometimes causes a problem in video light. In addition, there was a problem that caused a decrease in contrast.

  In general, a large diffusion angle in the horizontal direction is secured by the lenticular lens, and the vertical direction is diffused by the light diffusion layer. However, since there is a limit to the amount of the light diffusing agent added from the viewpoint of stray light and contrast, there are cases where a sufficient diffusion angle cannot be obtained by vertical light diffusion using the light diffusion layer.

  Therefore, Patent Document 1 discloses an optical sheet provided with a lenticular lens layer having two types of parallel lenticular lenses. This is called a so-called cross lenticular lens, and includes a lenticular lens arranged in parallel on the light incident side with the vertical direction as the longitudinal direction, and a lenticular lens arranged in parallel on the light output side with the horizontal direction in the longitudinal direction. Further, a resin layer laminated on the light exit side thereof, and a light shielding layer laminated on the light exit side of the resin layer and having a transmission aperture at a substantially focal position of the lenticular lens are provided. In addition, a light diffusion layer (front plate) for assisting diffusion of image light is provided on the light output side of the light shielding layer. According to this, although the diffusion layer is still necessary, the amount of the diffusing agent in the diffusion layer can be kept low, the above stray light can be suppressed, the contrast is prevented, and the adverse effect on the image can be reduced. It becomes.

JP 2004-246352 A

  However, in the optical sheet described in Patent Document 1, the vertical viewing angle has been improved, but further improvement has been required. In addition, a thick resin layer is formed between the lens surface on the light exit side and the light shielding layer, and it has been necessary to improve to meet the recent demand for higher density and higher definition.

  In addition, due to the trend of social resource reuse in recent years, there has been a demand to peel off the lenticular lens layer and the diffusion layer in the optical sheet for reuse. However, as described as one aspect of the optical sheet described in Patent Document 1, conventionally, the lenticular lens layer and the diffusion layer are bonded by an ultraviolet curable resin or the like, and it has been difficult to be reused. . Moreover, once bonded, it could not be peeled off and the bonding error could not be corrected.

  On the other hand, Patent Document 1 also discloses that the diffusion layer is provided independently. However, there is a risk of contamination due to foreign matters such as dust or position shift due to changes over time, which is more reliable. Adhesion was required to provide the optical sheet.

  Accordingly, an object of the present invention is to provide an optical sheet that can have a large diffusion angle in any direction and an optical sheet that can be easily reused.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The invention according to claim 1 is an optical sheet (10) including a lenticular lens layer (11) and a light shielding layer (15) from the light incident side, wherein the lenticular lens layer is a single base sheet (14). ) On the other side of the base sheet in a direction orthogonal to the incident side lenticular lens. The incident side lenticular lens portion (12) has a plurality of lenticular lenses 12a, 12a,. A plurality of lenticular lenses (13a, 13a,...) Arranged in parallel, and a light-shielding layer on the light-exiting side surface of the light-emitting side lenticular lens part. ...), and an optical sheet having transmission apertures (17, 17, ...) provided close to the focal position of the lenticular lens of the light incident side lenticular lens portion To solve the above problems by providing.

  According to a second aspect of the present invention, at least one of the light incident side lenticular lens portion (12) and the light outgoing side lenticular lens portion (13) of the optical sheet (10) according to the first aspect is made of an ultraviolet curable resin. It is characterized by.

  According to a third aspect of the invention, at least one of the light incident side lenticular lens portion (12) and the light outgoing side lenticular lens portion (13) of the optical sheet (10) according to the first aspect is made of a thermoplastic resin. It is characterized by.

  The invention according to claim 4 includes an adhesive layer (20) and a light diffusion further on the light exit surface side of the light shielding layer (15) of the optical sheet (10) according to any one of claims 1 to 3. Layer (25), and the adhesive layer is a hot-melt adhesive layer disposed between the light-shielding layer and the light diffusion layer along the outer peripheral edge of the light diffusion layer. And

  Here, the “outer peripheral end portion” means an end portion that does not contribute to providing an image, such as an attachment portion of an optical sheet to a television.

  According to a fifth aspect of the present invention, the part surrounded by the light shielding layer (15), the light diffusion layer (25), and the hot melt adhesive layer (20) of the optical sheet (10) according to the fourth aspect is negative. It is characterized by being pressured.

  Invention of Claim 6 is a method of manufacturing the optical sheet (10) as described in any one of Claims 1-5, Comprising: On the front and back of a base sheet (14), the incident side lenticular lens part ( 12) and a method of manufacturing an optical sheet including a step of molding the light-emitting side lenticular lens portion (13) and a step of forming a light shielding layer (15) on the surface of the light-emitting side lenticular lens portion. Resolve.

  Invention of Claim 7 is a method of manufacturing the optical sheet of Claim 4 or 5, Comprising: The incident side lenticular lens part (12) and the light emission side lenticular lens part on the front and back of a base sheet (14) A step of molding (13), a step of forming a light shielding layer (15) on the surface of the light exit side lenticular lens portion, a step of providing a hot melt adhesive layer (20) along the outer peripheral edge of the light shielding layer, Provided is a method for producing an optical sheet, comprising: a step of laminating a light diffusion layer (25) on the opposite side of the hot melt adhesive layer from the light shielding layer; and a step of applying a high frequency alternating magnetic field to the hot melt adhesive. This solves the problem.

  According to an eighth aspect of the present invention, the step of forming the light shielding layer (15) on the surface of the light output side lenticular lens portion (13) of the method for producing an optical sheet according to the sixth aspect or the seventh aspect comprises the light output side lenticular lens portion. Including a step of supplying a material for forming a light-shielding portion (16, 16,...) Over the entire surface and a step of irradiating light from the light incident side lenticular lens portion (12) side, and transmitting by the ablation action of the irradiation. It is characterized in that a transmissive opening is formed by removing a material for forming a light shielding portion in a portion corresponding to the opening (17, 17,...).

  By the optical sheet of the present invention and the method for manufacturing the optical sheet, the light incident side lenticular lens and the transmission opening of the light shielding layer are arranged close to each other. Thus, when the focal point of the lens is formed at a position close to the transmission aperture, it can be condensed with a large angle. That is, it is possible to increase the diffusion angle while maintaining a high contrast ratio and a high contrast ratio. In addition, since the lens surface of the light exit side lenticular lens is in contact with the transmission aperture and is a layer in which air or negative pressure is applied, the difference in refractive index can be increased, and the diffusion angle can be increased here. As described above, it is possible to provide an optical sheet that can take a large diffusion angle in any of horizontal, vertical, and oblique directions therebetween.

  Furthermore, since the adhesive of the diffusion layer is made of a hot-melt adhesive that can be remelted, the optical sheet can be easily peeled off and reused. In addition, since it can be easily peeled off, it can be reattached, and the manufacturing yield can be improved. The adhesive is disposed only in a portion that does not contribute to providing the image of the optical sheet. Therefore, even if adhesion and peeling are repeated, damage to the optical function is not caused to each layer, so that quality can be maintained and reliability can be improved even after repeated use. is there.

  Such an operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  1 is an exploded perspective view showing a part of an optical sheet 10 according to an embodiment of the present invention, FIG. 2 is a horizontal sectional view, and FIG. 3 is a vertical sectional view. In FIGS. 1 to 3, the layer structure is shown by paying particular attention to the end portion of the optical sheet 10. In FIG. 1, a Fresnel lens sheet is arranged on the light source side in the upper left of the drawing. The lower right side of the page is the observer side. 2 and 3, the left side of the drawing is the light source side, and the right side of the drawing is the viewer side. In FIG. 3, the cross section of a site | part which is different above and below the dashed-dotted line is shown. Specifically, as described later, the upper side of the alternate long and short dash line is a cross section including the light shielding portion 16, and the lower side of the alternate long and short dash line is a cross section including the transmission opening 17. In addition, in FIGS. 1 to 3, some of the repetitive symbols are omitted for easy viewing. The configuration of the optical sheet 10 will be described with reference to FIGS.

  The optical sheet 10 includes a lenticular lens layer 11, a light shielding layer 15, a hot melt adhesive layer 20, and a light diffusion layer 25 in this order from the light source side. Each will be described below.

  The lenticular lens layer 11 includes a base sheet 14, a light incident side lenticular lens portion 12 disposed on the light source side of the base sheet 14, and a light exit side lenticular lens portion 13 disposed on the observer side of the base sheet 14. Have.

  The base sheet 14 is a sheet serving as a basis for the light incident side and light output side lenticular lens portions 12 and 13 and is formed of a material that transmits light. Although it will not specifically limit if it is such a material, For example, this includes, for example, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, Ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer elastomer, acid-modified polyolefin, styrene-butadiene-acrylonitrile copolymer, polyamide, polycarbonate, polysulfone, polyacetal, poly Methyl methacrylate, polyphenylene oxide, polyurethane, polyethylene terephthalate (may be abbreviated as “PET”), polybutadiene terephthalate, simple substance such as nylon, or mixture (coextruded film, etc.) , And it can be exemplified a laminate Hinto.

  The thickness of the base sheet 14 is usually determined by the focal length of the lenticular lenses 12a, 12a,. This is because the focal point is preferably provided at a position close to the transmission opening 17 of the light shielding layer 15 as described later. Accordingly, the thickness of the base sheet 14 is not particularly limited, but is usually 30 to 200 μm, and about 30 μm is preferable for a high-definition optical sheet.

  In addition, the base sheet 14 has a different form depending on the material to be used and is not particularly limited. However, it is preferable to use PET, and its refractive index is about 1.60.

  The light incident side lenticular lens unit 12 is disposed on the light source side of the base sheet 14. A plurality of lenticular lenses 12a, 12a,... With the light source side convex and the vertical direction being the longitudinal direction are arranged in parallel in the horizontal direction. A normal lenticular lens can be used as the lenticular lenses 12a, 12a,..., For example, by arranging the lenticular lenses 12a, 12a,... Having a height of 20 to 100 μm at a pitch of 50 to 250 μm. The portion 12 can be formed.

  A material capable of transmitting light is applied to the lenticular lenses 12a, 12a,. For example, thermoplastic resins such as polyvinyl chloride, acrylic resins (PMMA, etc.), polystyrene, polycarbonate, unsaturated polyester, melamine, epoxy, polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate And thermosetting resins such as polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and triazine acrylate. Moreover, each can be used individually or in mixture of the said thermoplastic resin and thermosetting resin.

  In addition, these thermoplastic resins and / or thermosetting resins include thermoforming substances having radically polymerizable unsaturated groups, or radically polymerizable unsaturated monomers added thereto, and ionizing radiation and non-ionizing radiation curing. May be improved. Further, a so-called ultraviolet curable resin in which an ultraviolet absorber or a photoinitiator is further blended to improve the ultraviolet curable property can be used. Thus, for example, the lenticular lenses 12a, 12a,... Can be formed on the base sheet 14 by forming a shape with the above-mentioned semi-melted resin, and curing the lenticular lenses 12a, 12a,.

  The refractive index of the lenticular lenses 12a, 12a,... Formed of such a material is preferably about 1.4 to 1.6. A specific value is determined so that the focal point of the lenticular lenses 12 a, 12 a,... Is formed close to the transmission opening 17 of the light shielding layer 15 according to the relationship between the refractive index and the thickness of the base sheet 14. .

  The light exit side lenticular lens unit 13 is disposed on the viewer side of the base sheet 14. A plurality of lenticular lenses 13a, 13a,... With the observer side convex and the horizontal direction as the longitudinal direction are juxtaposed in the vertical direction. A normal lenticular lens can be used as the lenticular lenses 13a, 13a,..., For example, by arranging the lenticular lenses 13a, 13a,... Having a height of 5 to 40 μm at a pitch of 20 to 100 μm. 13 can be formed.

  A material capable of transmitting light is applied to the lenticular lenses 13a, 13a,. For example, thermoplastic resins such as polyvinyl chloride, acrylic resins (PMMA, etc.), polystyrene, polycarbonate, unsaturated polyester, melamine, epoxy, polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate And thermosetting resins such as polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and triazine acrylate. Moreover, each can be used individually or in mixture of the said thermoplastic resin and thermosetting resin.

  In addition, these thermoplastic resins and / or thermosetting resins include thermoforming materials having radically polymerizable unsaturated groups, or radically polymerizable unsaturated monomers added thereto, and ionizing radiation and non-ionizing radiation curing. May be improved. Further, a so-called ultraviolet curable resin in which an ultraviolet absorber or a photoinitiator is further blended to improve the ultraviolet curable property can be used. Thus, for example, the lenticular lenses 13a, 13a,... Can be formed with the resin half-melted, cured by irradiating with ultraviolet rays, and the lenticular lenses 13a, 13a,.

  The material used for the lenticular lenses 13a, 13a,... May be different from the material used for the lenticular lenses 12a, 12a,. However, the same is preferable from the viewpoints of handling, cost, and the like.

  The refractive index of the lenticular lenses 13a, 13a,... Formed of such a material is preferably about 1.4 to 1.6 μm. As a result, a difference in refractive index from the air or negative pressure air layer existing in the transmission opening 17 described later can be increased, and the diffusion angle can be increased accordingly.

  As described later, the lenticular lens layer 11 having the above-described configuration can diffuse not only the horizontal direction and the vertical direction but also an oblique direction between them. The sheet 10 can be provided.

  Next, the configuration of the optical sheet 10 will be described. The light shielding layer 15 is directly formed on the light output side lenticular lens portion 13 of the lenticular lens layer 11. The light shielding layer 15 has a light shielding function and is allowed to transmit light in a predetermined portion. Specifically, the light shielding layer 15 has transmission openings 17, 17,... At portions corresponding to the focal positions of the light incident side lenticular lenses 12 a, 12 a,. The light shielding portions 16, 16,... Since the focal points of the lenticular lenses 12a, 12a,... Are formed in parallel to the longitudinal direction of the lenticular lenses 12a, 12a,..., In this embodiment, the light shielding layer 15 includes the light shielding portions 16, 16,. 17 and so on become vertical stripes. Here, the ratio between the light shielding portions 16, 16,... And the transmission openings 17, 17,... Is a front view from the observer side of the optical sheet 10, and the light transmission portions 17, 17,. It is preferable that it is 30% or less with respect to the area.

  The light shielding layer 15 formed in this manner appropriately projects image light from the projector to the viewer side, and suppresses external light from entering the lenticular lens layer 11 to provide an image with good contrast. An optical sheet 10 that can be used.

  Further, in the lenticular lens layer 11 and the light shielding layer 15, in the optical sheet 10 of the present invention, other layers such as a resin layer or the like are provided between the light exit side lenticular lens portion 13 and the light shielding layer 15 as in the related art. Is not inserted. Thereby, the material for forming the other layer and the manufacturing process can be eliminated, and the configuration of the optical sheet 10 can be simplified and the cost can be reduced.

  Further, the light incident side lenticular lenses 12a, 12a and the transmission openings 17, 17,... Of the light shielding layer 15 are arranged close to each other. Thus, when the focal point of the lens is formed at a position close to the transmission openings 17, 17,..., It can be condensed with a large angle and then diffused. That is, it is possible to increase the diffusion angle while maintaining a high contrast ratio and a high contrast ratio. In addition, since the lens surfaces of the light exit side lenticular lenses 13a, 13a,... Are in contact with the transmission apertures 17, 17,..., This is a layer made of air or negative pressure. It can be taken big. Originally, when the light emission side is convex, it is difficult to increase the diffusion angle, but this is possible with the above configuration. As described above, it is possible to provide an optical sheet that can take a large diffusion angle in any of horizontal, vertical, and oblique directions therebetween. Specifically, the optical path will be described later.

  The light shielding portion 16 of the light shielding layer 15 is formed by mixing a light-shielding substance and / or a light-absorbing substance in the binder. Examples of binders include vinyl acetate, vinyl alcohol, styrene, α-methylstyrene, (meth) acrylic acid, (meth) acrylic acid esters (such as methyl methacrylate), fluorine-containing (meth) acrylic acid derivatives, and acrylonitrile as monomers. And a polymer obtained by polymerizing at least one monomer selected from olefins such as ethylene, propylene, butene and butadiene.

  In addition, cellulose derivatives such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, ethyl cellulose and nitrocellulose, polyesters such as polyamide, polyimide and polyethylene terephthalate, polycarbonate, polyarylate and polysulfone List transparent resins selected from polymers such as polyacetal, polyphenylene oxide, polyurethane, epoxy resin, phenolic resin, petroleum resin, natural rubber, synthetic rubber (butadiene rubber, etc.), silicon resin, fluororesin, etc. Can do.

  Furthermore, waxes may be used as the binder. These include natural waxes such as whale wax, beeswax, carnauba wax, candelilla wax, wood wax, montan wax, lanolin wax, paraffin wax, microcrystalline wax, ester wax, oxide wax, low molecular weight polyethylene wax, montan wax, chloride. Synthetic waxes such as paraffin, and also higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, furomenic acid, behenic acid, esters (fatty acid esters of sucrose, fatty acid esters of sulbitane, etc.), amides ( Stearamide, oleinamide, etc.).

  The substances that can be used as the binder described above can be used either alone or in combination of two or more.

  In addition, ammonium nitrate, potassium nitrate, or potassium perchlorate may be added to the binder as an oxidizing agent. Thereby, the combustibility at the time of laser irradiation can be improved.

  Examples of the light-shielding substance include carbon black, dark pigments, and dyes. This has a great effect of blocking light and preferably has a hue that does not hinder image display. Examples of this include black, gray, and white, but black is more preferable without external reflection.

  As the light-absorbing substance, a substance that can efficiently convert the energy of laser light into heat energy in the laser irradiation step can be used. This is because the transmission openings 17, 17,... Can be formed by ablation. Specifically, for example, for laser light in the range of near-infrared light (wavelength 700 to 2000 nm), fine powders and complexes of compounds containing copper or iron, carbon black, anthraquinone compounds, cyanine compounds, phthalocyanine compounds , Chromium, cobalt metal complex compound, tungsten hexachloride and tin chloride dissolved in methyl methacrylate (MMA) syrup, polymerized, dithiol metal complex (mainly nickel complex), squarylium compound, acetylene polymer and oxidizing agent There can be mentioned many inorganic complexes and organic compounds such as a substance obtained by doping the thiourea in the gas phase or liquid phase, a substance obtained by allowing cupric sulfide to act on thiourea, and an imonium material.

  As for laser light in the range of visible light (wavelength 400 to 700 nm), carbon black, nitroso dyes, nitro dyes, azo dyes, stilbene azo dyes, ketoimine dyes, triphenylmethane dyes, xanthene dyes, acridine dyes , Quinoline dyes, methine, polymethine dyes, thiazole dyes, indamine, indophenol dyes, azine dyes, oxazine dyes, thiazine dyes, sulfur dyes, amino ketones, oxyketone dyes, anthraquinone dyes, indigoid dyes, or phthalocyanine dyes, and more Zn, Cu, Al, Pb, Cr, Cd, Fe, Co, K, Na, Ti, Hg, Sr, Ca, Ba, Si, S, or the like, alloy, oxide, hydroxide, or these Inorganic compounds such as composites, etc. It can be.

  The light-shielding substance and light-absorbing substance described above are contained in the light-shielding layer in a total amount of about 1 to 70% by mass. If the content is less than 1% by mass, the formation accuracy of the transmission opening of the light shielding layer may be lowered. Moreover, when content exceeds 70 mass%, the effect of a mixing | blending will be saturated.

  Further, the configuration of the optical sheet 10 will be described. The hot melt adhesive layer 20 is a layer provided on the viewer side of the light shielding layer 15 at the outer peripheral end of the light shielding layer 15 and in a frame shape at a portion that does not contribute to the provision of images. The light shielding layer 15 and the light diffusion layer 25 are bonded by the adhesive of the hot melt adhesive layer 20. Here, the space formed between the lenticular lens layer 11 and the light diffusing layer 25 and inside the frame shape of the hot melt adhesive layer 20 was a negative pressure even in the air layer. It may be a layer. Actually, the lenticular lens layer 11 and the light diffusion layer 25 have predetermined elasticity. Therefore, even if the hot melt adhesive layer 20 exists with a certain thickness, the light shielding portions 16, 16,... Are observed in portions other than the hot melt adhesive layer 20, as shown in FIGS. The person side and the light source side of the light diffusion layer 25 are in close contact. As a result, most of the air or the layer corresponding to the negative pressure is the transmission openings 17, 17,.

  As described above, since the optical sheet 10 of the present invention is formed of a hot melt adhesive containing a thermoplastic resin, the adhesive can be remelted and peeled off by heating again. Thereby, the light-diffusion layer 25 and other layers can be peeled off, and both can be reused. Further, not only reuse but also re-sticking can be performed in the manufacturing process, and a sticking error can be corrected. As a result, the yield can be improved.

  Further, since the hot melt adhesive layer 15 is provided only at the outer peripheral end as described above, the thermal load is not exerted on the main parts of the lenticular lens layer 11 and the light shielding layer 15 at all during bonding and peeling. As a result, the lenticular lens layer 11 and the light shielding layer 15 can be maintained in quality without being damaged by adhesion and peeling. A specific bonding procedure will be described later. The adhesive layer does not exist at the site where the image light is transmitted, and the deterioration of the image due to the adhesive layer can be prevented. In addition, by adhering the light shielding layer 15 and the diffusion layer 25 with the adhesive layer 15 in this way, the air or the negative pressure portion can be stably maintained.

  The hot melt adhesive used for the hot melt adhesive layer 20 is a thermoplastic resin containing conductive particles. Although the kind of thermoplastic resin is not limited, For example, a polyvinyl chloride, an acrylic resin (PMMA etc.), polyethylene, a polypropylene, a polystyrene, a polycarbonate etc. can be mentioned. The conductive powder is not particularly limited as long as it is a substance that generates heat by an alternating magnetic field, and examples thereof include iron powder, carbon powder, and conductive resin.

  The light diffusion layer 25 is a layer containing a diffusing agent. Specifically, the light diffusion layer 25 is a layer in which light diffusion particles having a refractive index different from that of the base material are mixed. The base material is not limited as long as it is a material that can transmit light, and examples thereof include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and ethylene-acrylic acid copolymer. Polymer, ethylene-methacrylic acid copolymer, ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer elastomer, acid-modified polyolefin, styrene-butadiene-acrylonitrile copolymer , Polyamide, polycarbonate, polysulfone, polyacetal, polymethyl methacrylate, polyphenylene oxide, polyurethane, polyethylene terephthalate (may be abbreviated as “PET”), polybutadiene terephthalate, nylon, etc. Or mixture (coextruded film, etc.), and can be exemplified a laminate Hinto.

  The light diffusing particles are light transmissive particles having a refractive index different from that of the base material as described above. The material is not particularly limited as long as it has such properties, but inorganic fine particles (glass beads, silica, aluminum hydroxide, etc.), organic polymer fine particles (methyl methacrylate-based crosslinked polymer fine particles, etc.), etc. Can be mentioned. Among them, organic polymer fine particles are preferable because the refractive index can be set to a predetermined value by appropriately selecting a copolymer composition, and those having good transparency can be easily obtained. The average particle size is preferably in the range of 5 to 30 μm, and more preferably 10 to 20 μm.

  The light diffusion layer 25 can be easily peeled off by the optical sheet 10 having the above configuration. In addition, since no thermal load is applied to the lenticular lens layer 11 and the light shielding layer 15 during the bonding and peeling, the respective layers are not damaged. Therefore, it is possible to obtain an optical sheet that does not cause product deterioration due to adhesion / peeling for reuse.

  A functional sheet may be further laminated on the observer side on the optical sheet. Examples thereof include various layers having AR, AS, and AG functions. Here, “AR” is an abbreviation for “anti-reflection” and a function for suppressing light reflectance, and “AS” is an abbreviation for “anti-static” and means an antistatic function. “AG” is an abbreviation for “anti-glare” and is a function capable of preventing surface glare.

  Next, the optical path will be described with reference to FIGS. FIG. 4 is a diagram showing an example of an optical path in a horizontal section by a dashed-dotted arrow, and FIG. 5 is a diagram showing an example of an optical path in a vertical section by a dashed-dotted arrow. 4 and 5, the left side of the drawing is the light source side, and the right side of the drawing is the observer side. As shown in FIG. 4, the image light is condensed by the lenticular lenses 12 a, 12 a,... Of the light incident side lenticular lens unit 12. At this time, the focal point is formed at a position close to the transmission openings 17, 17,. The light is diffused on the observer side of the focal point. Therefore, main image light from the projector side can be transmitted through the light shielding layer 15 while maintaining its intensity generally. Thereby, a bright image can be provided to the observer. Further, in the optical sheet 10 of the present invention, there is no other layer other than the base sheet 14 between the light shielding layer 15 and the lenticular lenses 12a, 12a,. Therefore, even if the lenticular lenses 12a, 12a,... Have a short focal point, the light shielding portions 16, 16,... Are large and the transmission openings 17, 17,. It can be focused with an angle. Thereby, it is possible to obtain a large contrast while obtaining a large diffusion angle of the image light.

  On the other hand, as shown in FIG. 5, the image light from the lenticular lenses 12a, 12a,... Is condensed on the viewer side by the lenticular lenses 13a, 13a,. .. Is focused on the viewer side of the lenticular lenses 13a, 13a,..., And image light is diffused on the viewer side of the focus. At this time, since the lens surface is in contact with the air layer or an air layer having a negative pressure, the difference in refractive index is large, and a large refraction angle can be obtained. Therefore, since all of the image light transmitted through the lenticular lenses 13a, 13a,... Is projected while being diffused largely to the viewer side, it is possible to provide a bright image with a large diffusion angle. At this time, the image light entering the lenticular lenses 13a, 13a,... Is image light that already contains elements that are diffused in the horizontal direction by the lenticular lenses 12a, 12a,. Therefore, the image light projected from the lenticular lenses 13a, 13a,... Becomes image light having a diffusion component not only in the vertical and horizontal directions but also in any direction.

  Next, an example of the manufacturing method of the optical sheet 10 will be described. In the method of manufacturing the optical sheet 10, a step of molding the light incident side lenticular lens portion 12 and the light emitting side lenticular lens portion 13 on the front and back of the base sheet 14, and the light shielding layer 15 is formed on the surface of the light emitting side lenticular lens portion 13. Process. Furthermore, the manufacturing method includes a step of providing a hot melt adhesive along the outer peripheral end of the light shielding layer 15 on the viewer side, and a light diffusion layer 25 is laminated on the opposite side of the hot melt adhesive from the light shielding layer 15. Process. The method further includes a step of applying a high-frequency alternating magnetic field so that the hot melt adhesive layer 20 is contained in the magnetic field from either side of the laminated lenticular lens layer 11 or the light diffusion layer 25. Each step will be described below.

  The step of molding the light incident side lenticular lens portion 12 and the light outgoing side lenticular lens portion 13 on the front and back of the base sheet 14 is performed by, for example, a molding apparatus 30 schematically shown in FIG. The molding apparatus 30 includes a first molding roll 31 on which molds corresponding to the light incident side lenticular lenses 12a, 12a,... And a second mold on which molds corresponding to the light exit side lenticular lenses 13a, 13a,. The molding roll 32 and the ultraviolet irradiation apparatuses 33 and 34 provided so that irradiation of each surface of the 1st molding roll 31 and the 2nd molding roll 32 is possible. A nip roll 35 is provided with a predetermined gap from the first molding roll 31.

  First, the base sheet 14 is supplied from the previous process side of the molding apparatus 30 (the left side in FIG. 6). The base sheet 14 supplied to the molding manufacture 30 proceeds in the direction indicated by the arrow A, and is sandwiched between the nip roll 35 and the first molding roll 31 and is in close contact with the first molding roll 31.

  On the other hand, an ultraviolet curable resin is supplied to the surface of the first molding roll 31 before the base sheet 14 comes into close contact therewith. The ultraviolet curable resin is in close contact with the base sheet 14 and the lens shape of the first molding roll 31 is transferred to one surface of the base sheet 14. In this state, the first molding roll 31 rotates in the direction indicated by the arrow C and enters the ultraviolet irradiation range of the ultraviolet irradiation device 33, so that ultraviolet rays are irradiated. As a result, the ultraviolet curable resin is cured, and the lenticular lenses 12 a, 12 a,... Are molded on one surface of the base sheet 14.

  Thereafter, the base film 14 with the lenticular lens molded on one surface is moved between the first molding roll 31 and the second molding roll 32 by the rotation of the first molding roll 31. At this time, the ultraviolet curable resin is supplied to the surface of the second molding roll 32 before the base sheet 14 comes into close contact therewith. The ultraviolet curable resin is supplied from a resin pool provided between the first molding roll 31 and the second molding roll 32.

  Then, the base sheet 14 and the ultraviolet curable resin are in close contact with each other, and the lenticular lens in a direction orthogonal to the lenticular lenses 12a, 12a,... Already molded as described above is transferred to the other surface of the base sheet 14. In this state, the second molding roll 32 rotates in the direction indicated by the arrow D and enters the ultraviolet irradiation range of the ultraviolet irradiation device 34, so that ultraviolet rays are irradiated. Thereby, the ultraviolet curable resin is cured and the lenticular lenses 13a, 13a,... Are molded on the other surface of the base sheet 14. Thus, the lenticular lens layer 11 is molded and sent to the subsequent process according to the arrow B.

  Examples of the step of forming the light shielding layer 15 on the surface of the light exit side lenticular lens portion 13 include the following. An ultraviolet curable resin containing a light absorbent is applied to the entire side surface of the light-emitting side lenticular lens portion 13 of the lenticular lens layer 11 molded by the above method. Next, the coated part is cured by irradiating with ultraviolet rays. Thereafter, as shown in FIG. 7, the laser is irradiated from the light incident side lenticular lens portion 12 side. As a result, the laser beam transmitted through the light incident side lenticular lens portion 12 and condensed is irradiated onto the cured coating layer at the position indicated by E, and this is removed by the action of ablation. Therefore, the transmissive openings 17, 17,... Of the light shielding layer 15 are formed by the removal. On the other hand, the portions that have not been removed remain as the light shielding portions 16, 16,. Here, laser irradiation is performed after curing, but the present invention is not necessarily limited thereto. Specifically, the transmission opening can be formed even by laser irradiation before curing.

  The step of providing the hot melt adhesive along the outer peripheral edge of the light shielding layer 15 includes disposing the hot melt adhesive at the outer peripheral edge of the optical sheet 10 that does not contribute to providing an image, such as the attachment edge. It is a process. As the hot melt adhesive, those that are normally distributed can be used. Therefore, it may be a tape or a liquid. The arrangement method is appropriately selected according to the selected type.

  The step of laminating the light diffusion layer 25 on the opposite side of the light-shielding layer 15 of the hot melt adhesive may be performed by bringing the hot melt adhesive layer 20 and the light diffusion layer 25 into contact with each other. At this time, you may perform the said lamination | stacking in the atmosphere made into the negative pressure. As a result, the light shielding portions 16, 16,... Of the light shielding layer 15 and the light diffusion layer 25 can be brought into close contact with each other, and foreign matter such as dust can be prevented from being mixed and uneven contact can be prevented.

  The step of applying a high frequency alternating magnetic field is a step of applying a high frequency alternating magnetic field to the hot melt adhesive layer by a high frequency transmitter. As a result, the conductive material contained in the hot melt adhesive layer is heated, and the surrounding adhesive melts to develop an adhesive force. Accordingly, since only the adhesive layer is heated, the other layers can be bonded without applying a large thermal load. Further, due to the above-described properties of the hot melt adhesive, it can be melted again by adding a high frequency alternating magnetic field again. Thereby, it can peel and can use for reuse or re-stick. A commercially available high frequency transmitter can be applied. The type is not particularly limited, and may be a stationary type or a portable type.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the invention is limited to the embodiments disclosed herein. However, the invention can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an optical sheet accompanying such a change, and a manufacturing method thereof are also included in the technical scope of the present invention. Must be understood as being.

It is a disassembled perspective view of the optical sheet concerning one Embodiment of this invention. It is a horizontal sectional view in the edge part of the optical sheet concerning one Embodiment of this invention. It is a vertical sectional view in the edge part of the optical sheet concerning one embodiment of the present invention. It is a figure for demonstrating the example of an optical path in the horizontal cross section of an optical sheet. It is a figure for demonstrating the example of an optical path in the vertical cross section of an optical sheet. It is a schematic diagram of the shaping | molding apparatus which shape | molds a lenticular lens layer. It is a figure for demonstrating the formation method of the permeation | transmission opening using an ablation effect. It is the figure which showed the structure of the projection television typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical sheet 11 Lenticular lens layer 12 Light-incidence side lenticular lens part 13 Light emission side lenticular lens part 14 Base sheet 15 Light-shielding layer 16 Light-shielding part 17 Transmission opening 20 Hot melt adhesive layer 25 Light diffusion layer 30 Molding apparatus 31 1st molding roll 32 Second molding roll 33 UV irradiation device 34 UV irradiation device 35 Nip roll

Claims (8)

An optical sheet comprising a lenticular lens layer and a light shielding layer from the light incident side,
The lenticular lens layer is
A light incident side lenticular lens portion in which a plurality of lenticular lenses are arranged in parallel on one surface of one base sheet;
On the other surface of the base sheet, there is a light exit side lenticular lens portion in which a plurality of lenticular lenses are arranged in a direction orthogonal to the light entrance side lenticular lens,
The light shielding layer is
An optical sheet having a light-transmitting opening provided on a light-exiting side surface of the light-exiting-side lenticular lens unit and a light-transmitting opening provided close to a focal position of the lenticular lens of the light-incident-side lenticular lens unit.   The optical sheet according to claim 1, wherein at least one of the light incident side lenticular lens portion and the light outgoing side lenticular lens portion is made of an ultraviolet curable resin.   2. The optical sheet according to claim 1, wherein at least one of the light incident side lenticular lens portion and the light outgoing side lenticular lens portion is made of a thermoplastic resin. Further provided on the light exit surface side of the light shielding layer, an adhesive layer and a light diffusion layer,
The adhesive layer is
It is a hot-melt-adhesive agent layer arrange | positioned along the outer peripheral edge part of this light-diffusion layer between the said light shielding layer and the said light-diffusion layer, The any one of Claims 1-3 characterized by the above-mentioned. The optical sheet according to 1.   The optical sheet according to claim 4, wherein a portion surrounded by the light shielding layer, the light diffusing layer, and the hot melt adhesive layer has a negative pressure. A method for producing the optical sheet according to any one of claims 1 to 5,
Molding the light incident side lenticular lens part and the light exiting side lenticular lens part on the front and back of the base sheet;
Forming the light shielding layer on the surface of the light exit side lenticular lens part. A method for producing the optical sheet according to claim 4 or 5,
Molding the light incident side lenticular lens part and the light exiting side lenticular lens part on the front and back of the base sheet;
Forming the light shielding layer on the surface of the light exit side lenticular lens portion;
Providing the hot melt adhesive layer along the outer peripheral edge of the light shielding layer;
Laminating the light diffusion layer on the opposite side of the hot melt adhesive layer from the light shielding layer;
Applying a high-frequency alternating magnetic field to the hot-melt adhesive. The step of forming the light shielding layer on the surface of the light exit side lenticular lens portion,
Supplying a material for forming the light-shielding portion over the entire surface of the light-emitting side lenticular lens portion;
Irradiating light from the light incident side lenticular lens part side, and
8. The optical sheet according to claim 6, wherein the transmission aperture is formed by removing a material forming the light shielding portion in a portion corresponding to the transmission aperture by an ablation action of the irradiation. Method.

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