JP2008015352A - Optical sheet and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet having excellent light diffusing function or both functions of excellent light collecting function and excellent light diffusing function by providing a nonconventional structure. <P>SOLUTION: A light diffusible prism sheet 30 is structured by filling light diffusible particles 14 into transparent vessel 12 formed thin and having a sheet like outside shape and forming a prism shaped part 16A at least on one of the front and the rear surface of the transparent vessel 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical sheet and a method for manufacturing the optical sheet, and more particularly to an optical sheet used for a mobile phone, a digital camera, a television (TV), a liquid crystal display such as a projector, an illumination device, and the like, and a method for manufacturing the optical sheet.

  In recent years, for use in liquid crystal displays such as mobile phones, digital cameras, televisions (TVs), projectors, etc., a light diffusion sheet that diffuses light from a light source such as a light guide plate, and front brightness by condensing light in the front direction An optical sheet such as a condensing sheet (prism sheet) is used to improve the brightness. In this case, there are many examples in which various optical sheets are laminated and used. For example, in Patent Document 1, a reflective polarizing sheet, a retardation sheet, and a semi-transmissive semi-reflective layer are laminated in an arbitrary order, and further, an absorptive polarizing sheet is laminated outside these three layers. A semi-reflective polarizing film is provided. And as many as five layers of sheets are interposed between the light source device and the liquid crystal cell. With this configuration, it is said that screen luminance is increased or power consumption is suppressed. Patent Document 2 discloses a light control sheet in which a light diffusing sheet and a light collecting sheet are laminated to have both a light diffusing function and a light collecting function.

Furthermore, as disclosed in Patent Documents 3 to 6, a light diffusing sheet and a light condensing function are integrated by providing the light diffusing sheet with a light condensing function. And in these patent documents 3-6, as a method for exhibiting a light-diffusion function, the method of adhering a fine particle to a sheet | seat surface with a binder, the method of containing a light-diffusion agent in resin, the foamability in resin There has been proposed a method of foaming the composition to contain fine bubbles in the resin. For example, Patent Document 3 discloses a light diffusion sheet obtained by laminating a light diffusion layer containing a binder resin and resin particles and having an uneven surface on a transparent support, and has a total light transmittance of 70.0% or more and a haze. Is 80.0% or more, and the image clarity of transmission is 21.0% or more and less than 25.0%, so that light diffusion is achieved with high diffusibility and high brightness in the front direction. A sheet is disclosed. In Patent Document 4, a plurality of ridges made of prisms are formed on at least one surface of a light diffusion sheet having a thickness of 0.5 to 3 mm made of a transparent resin containing a light diffusing agent and a total light transmittance of 60 to 95%. A prism-integrated light diffusing plate having a portion is disclosed. Cited Document 5 proposes a light reflector having a high reflectance and a thin film, in which fine bubbles foamed by a foamable composition are contained in a resin sheet. Cited Document 6 discloses a light path control diffusion sheet in which a light diffusing agent is kneaded into a resin fabric to have a light diffusing function, and a prism portion is formed on the surface of the kneaded resin.
JP 2004-184575 A JP-A-5-173134 JP 2003-107214 A JP-A-2005-321681 Japanese Patent Application Laid-Open No. 2005-055883 JP 2000-206318 A

  Thus, optical sheets having various configurations in which the light diffusing function and the light collecting function are integrated and optical sheets having various configurations for providing the light diffusing function have been proposed. It has various drawbacks in obtaining processability and highly functional light diffusibility. For example, when the light diffusing agent (particles) is kneaded into the resin dough and has a light diffusing function as in the cited document 6, the particles are uniformly distributed in the dispersion (resin dough) in order to ensure the dispersibility of the particles. Difficult to disperse. For this reason, there is a problem that, starting from the selection of the dispersion liquid, it is necessary to make trial and error until finding the appropriate processing conditions for forming the optical sheet. If it is unavoidable, the selection of the dispersion and the conditions must be repeated. Similarly, as in Patent Document 5, it is difficult to uniformly foam a resin sheet containing a fine bubble foamed by a foamable composition (by trial and error such as conditions). Workability problems).

  Furthermore, in the case of a type in which the particles are not completely buried in the resin dough, but just half are buried, trial and error are repeated. If the particles are not half buried and the height of the particles protruding from the resin dough is random, scattering will increase due to interface reflection, resulting in reduced light collection efficiency (collection due to uneven particle height). Light problems).

  In addition, the type in which particles are contained in the surface portion of the binder layer as in Patent Document 3, the powder is likely to be generated during the processing of the liquid crystal panel, and there is only a risk of making the liquid crystal panel itself defective. In addition, it is difficult to bond with other optical sheets such as prism sheets (problems when processing liquid crystal panels).

  The present invention has been made in view of such circumstances, and has been a conventional defect, a problem of workability due to trial and error such as conditioning, a problem of light condensing due to uneven particle height, a liquid crystal panel An object of the present invention is to provide an optical sheet that can improve all of the problems during processing and that is excellent in the light diffusing function or both the light collecting function and the light diffusing function.

  According to a first aspect of the present invention, in order to achieve the above object, light diffusion into the gas phase in the thin layer cavity of a transparent container having a thin outer shape formed in a sheet shape and a thin layer cavity formed therein is achieved. Provided is an optical sheet filled with a conductive fine particle.

  In the optical sheet according to claim 1 of the present invention, the light diffusing fine particles are filled in the gas phase in the thin layer cavity of the transparent container whose outer shape is thinly formed into a sheet shape. Thereby, since it has a high-performance light scattering property due to the difference in refractive index between the gas and the light diffusing fine particles, a light diffusing sheet that exhibits a high light diffusing function can be provided.

  Moreover, in the case of the present invention, since light diffusing fine particles are filled in the gas phase in the thin layer cavity of the transparent container, there is a problem of workability due to trial and error such as conditions that was a conventional defect. In addition, it is possible to improve all of the light-collecting problems due to the unevenness of the particle height and the problems in processing the liquid crystal panel. In addition, as the light diffusing particles, a resin, a metal, or the like can be suitably used.

  A second aspect of the present invention is characterized in that, in the first aspect, a prism-shaped portion is formed on at least one of the front and back surfaces of the transparent container.

  As described in claim 1, the optical sheet according to claim 2 has high light by being filled with light diffusing fine particles in a gas phase in a thin layer cavity of a transparent container whose outer shape is thinly formed into a sheet shape. A diffusion function can be obtained, and furthermore, since a prism-shaped portion is formed on at least one of the front and back surfaces of the transparent container, a high light collecting function can also be obtained. Thereby, it is possible to provide an optical sheet (light diffusive prism sheet) having a light collecting function improvement (light luminance improvement) and a high diffusion function.

  A third aspect of the present invention is the method according to the first or second aspect, wherein the light diffusing fine particles filled in the transparent container are mixed with spacer particles having the same diameter as the thickness of the thin layer cavity. And

  In the optical sheet according to the third aspect, spacer particles having the same diameter as the thickness of the thin layer cavity are mixed as the light diffusing particles filled in the thin layer cavity of the transparent container. The role of. Thereby, while being able to form the thickness of a thin layer cavity part appropriately, the rigidity of an optical sheet can be raised.

  A fourth aspect of the present invention is the method according to the second or third aspect, wherein the concave / convex pattern of the prism-shaped portion is a convex quadrangular pyramid.

  The optical sheet according to claim 4 has a convex-concave pattern of the prism-shaped portion as a convex quadrangular pyramid, and as the concave-convex pattern, for example, a lens sheet in which convex lenses are arranged adjacently in one axial direction can also be used. . However, the occurrence of interference fringes can be reduced by making the concavo-convex pattern a convex quadrangular pyramid.

  According to a fifth aspect of the present invention, in order to achieve the above object, a tray forming step of forming a thin tray having an open upper surface using a transparent resin, and a prism-shaped portion is formed using the transparent resin. A lid forming step for forming a lid member, a filling step for filling the tray with light diffusing particles, a joining step for closing the upper surface of the tray with the lid member and joining the tray and the lid member; An optical sheet manufacturing method is provided.

  In the method for producing an optical sheet according to claim 5, a thin tray (a shallow container) and a lid member formed with a prism-shaped portion are formed of a transparent resin, and the lid is filled with light diffusing particles. The tray and the lid member are joined in a state where the lid is covered with the member. As a result, an optical device in which light diffusing particles are filled in a gas phase in a thin layer cavity of a transparent container (tray and lid member) whose outer shape is thinly formed into a sheet shape and in which a thin layer cavity is formed. Sheets can be manufactured.

  The tray formation method is not particularly limited. For example, a compression molding method in which a molten thermosetting resin is pressed into a tray shape by pressing with a male die and a female die is preferably used. can do. Further, the method of forming the lid member on which the prism-shaped portion is formed is not particularly limited. For example, an uneven roller in which an inverted type of the prism-shaped portion is formed on the roller surface on the coating layer surface of the ultraviolet curable resin coated on the transparent support. The method of transferring with can be suitably used.

  A sixth aspect of the present invention according to the fifth aspect is characterized in that a charging step for charging the tray with static electricity is performed before the filling step.

  According to the manufacturing method of claim 6, since the static electricity is charged in the tray so that the light diffusing particles are easily adhered to the tray by the static electricity, the light diffusing particles can be easily placed in the tray even in a thin tray. Can be filled.

  According to a seventh aspect of the present invention, in order to achieve the above object, a sheet forming step of forming at least two sheets formed with a prism-shaped portion using a transparent resin, and a filling port for filling the two sheets are provided. A bonding step of forming a bag-like body by bonding the periphery, a filling step of filling the bag-like body with light diffusing particles from the filling port, and a closing step of closing the filling port. An optical sheet manufacturing method is provided.

  In the manufacturing method according to claim 7, two sheets having prism-shaped portions formed of a transparent resin are formed, and light diffusing particles are filled from a filling port into a bag-like body in which the two sheets are joined in a bag shape. I did it. As a result, the light diffusing particles in the gas phase in the thin layer cavity of the transparent container (the bag-shaped container made of two sheets) having the outer shape formed into a thin sheet shape and the thin layer cavity formed inside. Can be produced. In the manufacturing method according to the seventh aspect, since the light diffusing particles are filled in the bag-like container, the light diffusing particles are hardly scattered to the outside.

  An eighth aspect of the present invention is characterized in that in any one of the fifth to seventh aspects, the transparent resin is any one of a thermoplastic resin, an ultraviolet curable resin, and a thermosetting resin.

  Claim 8 is because a thermoplastic resin, an ultraviolet curable resin, and a thermosetting resin are suitable as a resin for forming a transparent container or a prism-shaped portion by processing.

  As described above, according to the optical sheet and the manufacturing method thereof of the present invention, it is possible to provide an optical sheet excellent in the light diffusing function or both the light collecting function and the light diffusing function. It is possible to improve all the problems of the workability due to trial and error such as condition setting, the light condensing problem due to the unevenness of the particle height, and the problem at the time of processing the liquid crystal panel.

  Hereinafter, preferred embodiments of the optical sheet and the method for producing the same according to the present invention will be described in detail with reference to the accompanying drawings.

  First, some embodiments of the optical sheet manufactured by the method for manufacturing an optical sheet according to the present invention will be described, and then a method for manufacturing these optical sheets will be described.

[First Embodiment]
FIG. 1 is a configuration of a light diffusion sheet in the first embodiment of the optical sheet of the present invention, FIG. 1 is an external view, and FIG. 2 is a cross-sectional view taken along the line AA of FIG.

  As shown in FIGS. 1 and 2, the light diffusion sheet 10 is configured by filling a large number of light diffusing particles 14, 14... In a transparent container 12 whose outer shape is thinly formed into a sheet shape. The The transparent container 12 has a thin-layer cavity formed therein by joining the periphery of a shallow resin tray 18 having an open top surface and a resin lid plate 16 that closes the top surface of the tray 18 with a joint portion 20. A portion 22 is formed, and the light diffusing particles 14 are filled in the gas phase of the thin layer cavity portion 22.

  The transparent container 12 filled with the light diffusing particles 14 has a shape matched to the liquid crystal display element in which the optical sheet is incorporated, but is usually formed into a thin quadrilateral (regular quadrangle, rectangular). The transparent container 12 preferably has such a rigidity that the lid plate 16 and the bottom surface of the tray 18 do not come into contact with each other in a state before being filled with the light diffusing particles 14.

  The light diffusing particles 14 filled in the transparent container 12 are preferably those capable of diffusing and erasing the light diffusion pattern of the light guide plate and transmitting the incident light in the front direction. Such light diffusing particles 14 are preferably substantially spherical in shape.

  The light diffusing sheet 10 of the present invention utilizes the difference in refractive index between the gas in the transparent container 12 and the light diffusing particles 14, and the gas forming the gas phase in the thin layer cavity 22 is Air is common, but is not limited to air. For example, there may be a mode in which a gas other than air such as nitrogen or carbon dioxide gas is intentionally filled. Thus, by changing the type of gas, it is possible to use a subtle difference in refractive index depending on the type of gas.

  The color of the light diffusing particles 14 is preferably white or transparent, but may be colored such as red or black. A light diffusing particle 14 having a refractive index in the range of 1.4 to 1.6 can be preferably used.

  As a material of the light diffusing particles 14, a resin or a metal can be preferably used. The refractive index range of the light diffusing particles 14 is preferably in the range of 1.3 to 2.5, and more preferably in the range of 1.49 to 1.8.

  Such resin particles include acrylic resin particles (including thermoplastic and crosslinkable), silicon resin particles, nylon resin particles, styrene resin particles, polyethylene resin particles, benzoguanamine resin particles, and urethane resin particles. Various resin particles such as can be used. The difference in refractive index from the substrate (transparent container) is preferably 0.05 or less, and more preferably 0.02 or less. In particular, when the substrate is PET (polyethylene terephthalate), MBS (methyl methacrylate / butadiene / styrene) resin particles or PMMA (polymethyl methacrylate) resin particles close to a refractive index of 1.53 of PET are preferable.

  As such metal particles, silica, quartz, titanium oxide, zinc oxide and the like can be preferably used.

  As the light diffusing particles 14 to be filled in the transparent container 12, single-diameter light diffusing particles 14 can be used as shown in FIG. 1, but at least two kinds of large particles and small particles can be mixed. preferable. This is because, if there are many gaps between the light diffusing particles 14 filled in the thin layer cavity portion 22 in the transparent container 12, the reflection increases and the luminance decreases. This is because the closest packing (filling at a high density) can be performed by filling with. Specifically, the radius of the large particles is preferably 250 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm or less. As shown in FIG. 3, the radius of the small particle 14A in this case is preferably smaller than 2√2R-2R (about 0.828R), where R is the radius of the large particle 14B. As the small particles, for example, nano-sized nanoparticles pulverized by a bead mill can be preferably used.

  Further, as shown in FIG. 4A, in order to prevent dissipation of the light diffusion sheet 10 in the transparent container 12, when the diameter of the large particles 14B is L, the thickness T of the thin layer cavity portion 22 is: It is preferable to satisfy the relationship of T <2L. Therefore, as shown in FIG. 4B, it is preferable to interpose the spacer 19 having a height satisfying the relationship of T <2L in the thin layer cavity portion 22. As the material of the spacer 19, a resin material can be preferably used. The spacer 19 may have any shape. For example, as shown in FIG. 4C, the thin layer cavity 22 is separate from the large particles 14B and small particles 14A of the light diffusing particles 14 described above. It is also possible to mix spacer particles 19 ′ having a particle diameter equivalent to the thickness of the spacer. The spacer particles 19 ′ not only serve to satisfy the above-described relationship of T <2L, but also serve as a column that supports the cover plate 16 to increase the rigidity of the optical sheet.

[Second Embodiment]
5 and 6 show a second embodiment of the optical sheet of the present invention, which is a configuration of a light diffusing prism sheet 30 having both a light diffusing function and a condensing function. FIG. 5 is an external view, and FIG. 6 is a cross-sectional view taken along line BB in FIG. The same members as those in the first embodiment will be described with the same reference numerals.

  As shown in FIGS. 5 and 6, in the light diffusing prism sheet 30, the light diffusing particles 14 are filled in the transparent container 12 whose outer shape is thinly formed into a sheet shape. However, it is configured by forming a prism-shaped portion 16A on at least one of the front and back surfaces of the transparent container 12 (formed on the surface of the cover plate 16 in FIGS. 5 and 6). The light diffusing particles 14 filled in the transparent container 12 are the same as those in the first embodiment.

  The concavo-convex pattern of the prism shape portion 16A can be, for example, a concavo-convex pattern having a pitch P of 50 μm and a convex portion height of 25 μm. A preferable range of the pitch is 10 to 100 μm, and a preferable range of the convex portion height H is a range of 5 to 95 μm.

  The prism-shaped portion 16A formed in the transparent container 12 is not particularly limited as long as it is a concave-convex pattern that can collect and diffuse incident light from the light guide plate to improve front luminance and reduce luminance unevenness. As shown in FIG. 5, convex lenses formed in one axis direction are formed adjacent to each other, and as shown in FIG. 7, a cone structure (FIG. 7 is a convex quadrangular pyramid) is vertically and horizontally grid-like. The concavo-convex pattern arranged in the can be preferably used. In this case, it is more preferable to use a convex quadrangular pyramid pattern to reduce the occurrence of interference fringes.

  8 to 10 are modified examples of the light diffusing prism sheet 30. FIG.

  The light diffusing prism sheet of FIG. 8 is obtained by hollowing out the inside of the prism shape portion 16A of FIG. Further, the light diffusive prism sheet 30 of FIG. 9 has a light diffusibility in the gas phase in the enlarged cavity portion 22A as an enlarged cavity portion 22A in which the thin layer cavity portion 22 is expanded to the hollowed portion of the prism shape portion. The particles 14 are filled.

  Further, the light diffusing prism sheet 30 in FIG. 10 is formed by forming prism-shaped portions 16 </ b> A on both the front and back surfaces of the transparent container 12. In FIG. 10, the transparent container 12 is configured by joining the two sheets 32, 32 on which the prism-shaped portion 16 </ b> A is formed by joining the joint portion 20, but the surface of the bottom plate of the tray 18 in FIG. 9. A prism-shaped portion 16A may be provided on the side.

  6 to 10 do not show the spacers 19 (or spacer particles 19 '), but it is preferable to use them.

[Optical sheet manufacturing method]
Next, a method for manufacturing the light diffusing prism sheet 30 will be described. In addition, although the manufacturing method of the light diffusable sheet 10 is not described, only the prism-shaped portion 16A of the light diffusing prism sheet 30 is not provided, and the basic manufacturing method is the same.

(First example)
The first example is a case where the transparent container 12 includes the tray 18 and the lid plate 16 having the prism-shaped portion 16A formed on the surface thereof as described with reference to FIGS. Note that an example of the outer shape of the light diffusing prism sheet 30 is a square sheet.

  The main steps for manufacturing the light diffusing prism sheet 30 of the first example are a tray forming step for forming a thin tray 18 whose upper surface is opened using a transparent resin, and a prism shape portion 16A using a transparent resin. A lid forming step for forming the lid plate 16 formed with a lid, a filling step for filling the tray 18 with the light diffusing particles 14, and a joining step for closing and joining the upper surface of the tray 18 with the lid plate 16. Is done.

  The tray forming step is not particularly limited as long as the above-described size and shape of the tray (a container having a shallow bottom) can be formed, but the compression forming method shown in FIG. 11 can be suitably employed.

  As shown in FIG. 11 (A), a female die 34 having a shallow concave shape with a square bottom, and a convex male die that is slightly smaller than the concave shape and fits into the female die 34. 36 is prepared, and a transparent thermosetting resin 38 is poured into the female mold 34. Next, as shown in FIG. 11 (B), by fitting the convex male mold 36 to the concave female mold 34 to close the molds 34 and 36, and heating while pressing, The thermosetting resin 38 ′ molded in the tray shape is cured. Next, as shown in FIG. 11C, the male mold 36 is separated from the female mold 34, the molds 34 and 36 are opened, and the molded product is taken out. Thereby, the thin and rigid tray 18 for filling the light diffusing particles 14 can be formed.

  On the other hand, the lid forming step is not particularly limited as long as the lid plate 16 having the prism-shaped portion 16A formed on the surface can be formed, but the uneven pattern transfer method shown in FIG. 12 can be suitably used.

  As shown in FIG. 12, a web-like transparent film 42 (support) wound around a delivery roll 40 is sent to the production line, and a coating solution of UV curable resin is first applied onto the transparent film 42 by a coating device 44. Is done. As the transparent film 42, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyolefin, acrylic, polystyrene, polycarbonate, polyamide, PET (polyethylene terephthalate), biaxially stretched polyethylene terephthalate, polyethylene Known materials such as naphthalate, polyamideimide, polyimide, aromatic polyamide, cellulose acylate, cellulose triacetate, cellulose acetate propionate, and cellulose diacetate can be used. Of these, polyester, cellulose acylate, acrylic, polycarbonate, and polyolefin can be preferably used. Moreover, it is preferable to increase the thickness of the transparent film 42 to such an extent that rigidity can be secured for the lid plate 16 to be formed.

  In FIG. 12, a die coater using an extrusion type coating head is used as the coating device 44, but another coating method may be used. Further, the supply amount of the supply pump 46 may be controlled so that the wet thickness of the coating liquid applied on the transparent film 42 is, for example, about 20 μm in the film thickness after solvent drying.

  Next, the transparent film 42 is conveyed to a drying device 48 where the organic solvent in the coating solution is volatilized and the coating layer is dried. Although it does not specifically limit as the drying apparatus 48, For example, the drying apparatus of a hot air circulation type can be used, and it is preferable that the temperature of hot air shall be about 100 degreeC.

  Next, the transparent film 42 is conveyed to the curing device 50. In the curing device 50, the concavo-convex pattern of the concavo-convex roller 50A is sandwiched between the concavo-convex roller 50A and the nip roller 50B on the surface of which the inverted pattern of the concavo-convex pattern of the prism-shaped portion 16A is formed. Transcript to. As the concavo-convex roller 50A, for example, a roller made of S45C having a length (a width direction of the transparent film) of 700 mm and a diameter of 300 mm and having a surface material of nickel can be used. A concavo-convex pattern can be formed on the entire circumference of the surface of the roller with a width of about 500 mm by cutting using a diamond tool (single point). As the nip roller 50B, for example, a roller having a diameter of about 200 mm and a silicon rubber layer having a rubber hardness of 90 on the surface can be preferably used. The nip pressure (effective nip pressure) for pressing the transparent film 42 by the uneven roller 50A and the nip roller 50B is preferably about 0.5 MPa.

  Then, in a state where the transparent film 42 is wound around the uneven roller 50A, the UV layer (irradiation) is irradiated to the coating layer surface by a UV irradiation device (not shown), and the uneven pattern transferred to the coating layer surface is cured. As a result, a belt-like sheet 42 ′ having a concavo-convex pattern of the prism-shaped portion 16 </ b> A formed on the surface is formed. The formed belt-like sheet 42 ′ is peeled off by the peeling roller 52 and taken up by the winding roller 54. The band-like sheet 42 ′ thus formed is cut into a desired size to form the cover plate 16 having the prism-shaped portion 16 </ b> A on the surface.

  The tray 18 formed as described above is charged with static electricity by an electrostatic charging device (not shown), and then the light diffusing particles 14 are sprayed and adhered to the tray 18. Thereby, the light diffusing particles 14 are filled in the tray 18. In this case, first, the large particles 14B diffused in the gas are sprayed and adhered in the tray 18, and then the static electricity is further charged on both the tray 18 and the large particles 14B, and then the small particles 14A diffused in the gas are added. It is preferable to deposit in the tray 18. As a result, the small particles 14A enter the gaps between the large particles 14B, so that the light diffusing particles 14 can be packed most closely, and a reduction in luminance can be prevented. The electrostatic charging may be performed not on the tray 18 but only on the light diffusing particles 14 or on both. Furthermore, it is better to fill the light diffusing particles 14 while applying ultrasonic vibration to the tray 18.

  Further, as a method for packing the light diffusing particles 14 into the tray 18 in a close-packed manner, a dispersion in which large and small light diffusing particles 14 are mixed and dispersed in a volatile dispersion such as an organic solvent is prepared. A method of evaporating only the dispersion after filling the tray 18 can also be preferably employed.

  Further, as another method for closely packing the light diffusing particles 14 into the tray 18, a self-organization accumulation method, which is one of the methods for aligning and accumulating various molecules on the solid surface, can be preferably employed. As for self-organization, as disclosed in Japanese Patent Application Laid-Open No. 2003-330119, accumulation is performed by a natural sedimentation method or the like. Also, the large particles 14B shown in FIG. 4 can be closely packed by first adhering to the tray 18 serving as a substrate and then later self-organizing small particles 14A having a diameter of 1 μm or more by coating or the like. In this case, if the diameter of the small particle 14A is less than 1 μm, light reflection occurs. In addition, it is preferable to use a polymer binder for the self-organization of the microparticles, whereby the cohesive force can be further increased.

  When the light diffusing particles 14 are filled in the tray 18, the open upper surface of the tray 18 is closed with the cover plate 16, and the periphery of the cover plate 16 and the tray 18 is joined. As a joining method, an adhesive can be used. As the adhesive, an adhesive that is bonded by heat or a catalyst is preferable. For example, a silicon-based adhesive, a polyurethane-based adhesive, a polyester-based adhesive, an epoxy-based adhesive, a cyanoacrylate-based adhesive, an acrylic-based adhesive, or the like. It can be used suitably. As other bonding methods, an ultrasonic welding apparatus or a laser welding apparatus can be used. As the laser welding apparatus, a YAG laser having a wavelength of 355 to 1064 nm, a semiconductor laser, a carbon dioxide gas laser having a wavelength of 9 to 11 μm, or the like can be used. Although it varies depending on the scanning speed of the laser beam and the thickness of the material, in general, good welding results can be obtained under the conditions of an output of 2 to 50 W and a frequency of 100 kHz.

  Thereby, the light diffusing particles 14 are filled in the transparent container 12 whose outer shape is thinly formed into a sheet shape, and the prism-shaped portion 16A is formed on at least one of the front and back surfaces of the transparent container 12. The light diffusing prism sheet 30 can be manufactured.

(Second Embodiment)
In the second example, as described with reference to FIG. 10, the transparent container 12 includes two sheets 32 having a prism-shaped portion 16 </ b> A formed on the surface.

  The main processes for manufacturing the light diffusing prism sheet 30 of the second example are a sheet forming process for forming two sheets 32, 32 having at least the prism-shaped portion 16A formed using a transparent resin, and two sheets A joining step of joining the periphery of the sheets 32 and 32 leaving the filling port to form a bag-like body, a filling step of filling the light-diffusing particles 14 from the filling port into the bag-like body, and closing the filling port Process.

  In the sheet forming process, as a method of forming the prism-shaped portion 16A, the compression forming method in the tray forming method described in the first example can be adopted. However, in this case, a prism-shaped concavo-convex pattern is formed on the convex surface of the convex male die 36 and the concave surface of the concave female die 34 so that the male die 36 and the female die 34 It is preferable that the concave and convex patterns are engaged with each other. For example, in the case of the prism-shaped portion 16A in which convex lenses formed in the uniaxial direction are formed adjacent to each other, an image in which the corrugated shape is continuous in the uniaxial direction is obtained. Further, in the case of the prism-shaped portion 16A in which convex quadrangular pyramids are formed in a grid pattern in the vertical and horizontal directions, an image in which convex quadrangular pyramid hats are continuously arranged in the vertical and horizontal directions is obtained. The sheet 32 to be formed is preferably thick enough to ensure rigidity.

  In addition, in the joining process for forming the bag-like body and the closing process for closing the filling port, the joining method using the adhesive, the joining method using ultrasonic welding, and the joining method using laser welding described in the joining process of the first example are applied. can do.

1 is an external view of a light diffusion sheet that is an embodiment of an optical sheet according to the present invention. Sectional drawing along the AA line of FIG. Explanatory drawing explaining the relationship between large particles and small particles of light diffusing particles Explanatory drawing explaining the relationship between the thickness of the thin layer cavity part of a transparent container, and the diameter of a large particle FIG. 3 is an external view of a light diffusing prism sheet which is another embodiment of the optical sheet according to the present invention. Sectional drawing along the BB line of FIG. External view showing another aspect of the prism-shaped portion formed on the light-diffusing prism sheet Sectional view when prism shape part of light diffusing prism sheet is hollow Sectional view when the light-diffusing particles are also filled in the prism-shaped portion of the light-diffusing prism sheet Sectional drawing explaining another aspect of a light-diffusion prism sheet Explanatory drawing of the tray formation process in the manufacturing method of a light diffusive prism sheet Explanatory drawing of the lid | cover formation process in the manufacturing method of a light diffusive prism sheet

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light-diffusion sheet (optical sheet of 1st Embodiment), 12 ... Transparent container, 14 ... Light-diffusible particle, 14A ... Small particle, 14B ... Large particle, 16 ... Cover plate, 16A ... Prism-shaped part, DESCRIPTION OF SYMBOLS 18 ... Tray, 19 ... Spacer, 19 '... Spacer particle, 20 ... Joint part, 22 ... Thin layer cavity part, 30 ... Light diffusing prism sheet, 32 ... Sheet, 34 ... Female metal mold, 36 ... Male metal mold , 38 ... thermosetting resin, 40 ... delivery roll, 42 ... transparent film, 42 '... belt-like sheet, 44 ... coating device, 46 ... supply pump, 48 ... drying device, 50 ... curing device, 50A ... uneven roller, 50B ... Nip roller, 52 ... Peeling roller, 54 ... Take-up roller

Claims (8)

  An optical sheet characterized in that light diffusing particles are filled in a gas phase in the thin layer cavity of a transparent container having an outer shape formed into a thin sheet and having a thin layer cavity formed therein.   The optical sheet according to claim 1, wherein a prism-shaped portion is formed on at least one of the front and back surfaces of the transparent container.   The optical sheet according to claim 1 or 2, wherein the light diffusing particles filled in the transparent container are mixed with spacer particles having the same diameter as the thickness of the thin layer cavity.   4. The optical sheet according to claim 2, wherein the concave / convex pattern of the prism-shaped portion is a convex quadrangular pyramid. A tray forming process for forming a thin tray with an open top using a transparent resin,
A lid forming step of forming a lid member having a prism-shaped portion formed using a transparent resin;
A filling step of filling the tray with light diffusing particles;
An optical sheet manufacturing method comprising: a joining step of closing the upper surface of the tray with the lid member and joining the tray and the lid member.   6. The method of manufacturing an optical sheet according to claim 5, wherein a charging step of charging the tray with static electricity is performed before the filling step. A sheet forming step of forming at least two sheets formed with a prism-shaped portion using a transparent resin;
A joining step of joining the periphery of the two sheets leaving a filling port to form a bag-like body;
A filling step of filling the bag-like body with light diffusing particles from the filling port;
And a closing step for closing the filling port.   The method for producing an optical sheet according to any one of claims 5 to 7, wherein the transparent resin is any one of a thermoplastic resin, an ultraviolet curable resin, and a thermosetting resin.

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