JP2006208874A - Light diffusion sheet, its manufacturing method, and transmission-type screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusion sheet without causing deformations in a stuck member, when a light diffusion sheet having a light diffusing function is manufactured by sticking together a film-shape lenticular lens member etc., and a rigid sheet type base member etc. <P>SOLUTION: The light diffusion sheet 10, which has a couple of plastic members 11 and 12 stuck together across an adhesion layer 13, while at least one of the couple of plastic members 11 and 12 and the adhesion member 13 has light diffusing functions, is characterized with a pair of plastic members 11 and 12 that are both ≥50 μm thick, and the adhesion layer 13 is formed of an acrylic polymer adhesive to a thickness of ≥30 μm, thereby solving aforementioned problem. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light diffusing sheet that is a component of a transmissive screen of a projection television, a manufacturing method thereof, and a transmissive screen.

  A projection television, which is a rear projection display device, includes a transmissive screen that projects image light emitted from a light source. This transmissive screen generally has a Fresnel lens sheet for deflecting image light projected from a light source to substantially parallel light (including parallel light) toward the viewer, and a field of view of the image by diffusing the substantially parallel light. And a lenticular lens sheet for widening the corners. As a light source, a three-tube CRT light source has been generally used, but LCD (Liquid Crystal Display) and DLP (Digital Light Processing) are used in response to recent demands for digitalization, high definition and compactness. Conventional single-tube light sources (hereinafter referred to as “single light sources”) have been used. When this single light source is used, there is an advantage that the still image and the character display become clearer by the pixel display which is the feature.

  By the way, a light diffusion sheet such as a lenticular lens sheet constituting a transmission screen has been conventionally manufactured by extrusion molding, and the lens pitch of the lenticular lens is relatively large. In such a light diffusing sheet, if a conventional three-tube CRT light source is used, the moire problem does not occur. However, when the pixel display type single light source as described above is used, the lens pitch of the lenticular lens sheet constituting the transmissive screen must be set to a fine pitch (0.3 mm or less) between the pixel and the lenticular lens. There is a problem that moire occurs.

  In extrusion molding, which is a conventional manufacturing method, it is difficult to make the lenticular lens sheet thin, so there is a problem that it is difficult to make the lens pitch a fine pitch of 0.3 mm or less, and the above moire problem is sufficiently solved. Was not done. Therefore, in recent years, as a lenticular lens sheet for a single light source, a method of forming a fine pitch lenticular lens with a radiation curable resin on a thin film such as a PET film has become common.

  However, the film-like lenticular lens member manufactured in this way has a small thickness, and when used as a constituent member of a transmission type screen, there is a problem that undulation is generated due to insufficient rigidity.

  For such a problem, a method of manufacturing a rigid lenticular lens sheet by bonding a film-like lenticular lens member and a relatively thick sheet-like support member is employed. Specifically, (1) a method in which an adhesive is applied on a rigid sheet-like support member, and then a film-like lenticular lens member is placed on the support member while being pressed with a nip roll, and then manufactured. (2) For example, as shown in FIG. 7, an adhesive film 73 is bonded to the bonding surface of a film-like lenticular lens member 71, and then the method A method (for example, refer to Patent Document 1) in which the pressure-sensitive adhesive film 73 is bonded to the rigid sheet-like support member 72 while being pressed by nip rolls 75 and 75 is employed.

For such a problem, a method of manufacturing a rigid lenticular lens sheet by bonding a film-like lenticular lens member and a relatively thick sheet-like support member is employed. Specifically, (1) The adhesive surface of the film-like lenticular lens member is directly coated with an adhesive to form an adhesive layer, and then the adhesive layer is placed on a rigid sheet-like support member. (2) As shown in FIG. 7, for example, an adhesive film 73 is bonded to the bonding surface of a film-like lenticular lens member 71, and then the adhesive film 73 is turned down to form a rigid sheet A method (for example, refer to Patent Document 1), which is mounted on the support member 72 and bonded while being pressed with nip rolls 75, 75, is employed.
JP 2001-215622 A (paragraph number 0029)

  However, since the adhesive layer in (1) and the adhesive film in (2) are both solid, for example, as shown in FIG. 7, a film-like lenticular lens member 71 and a rigid sheet-like support member 72, when a foreign substance 74 is mixed between the two, the thin film lenticular lens member 71 is deformed 76 due to the mixed foreign substance 74, resulting in a poor appearance. there were. In addition, when bubbles are mixed between the lenticular lens member and the support member, there is also a problem in that an image defect occurs due to the refraction angle of the image light being disturbed by the mixed bubbles.

  The present invention has been made to solve the above-described problems, and has an object of, for example, bonding a film-like lenticular lens member and a rigid sheet-like support member to have a light diffusion function. In the case of manufacturing a light diffusion sheet, even if bubbles or foreign matter are mixed between the bonding members, the light diffusion sheet that does not cause appearance defects or image defects on the bonding member and the transmission having the light diffusion sheet To provide a mold screen.

  The light diffusing sheet of the present invention that achieves the above object has a pair of plastic members bonded via an adhesive layer, and at least one of the pair of plastic members and the adhesive layer has a light diffusing function. The pair of plastic members are both 50 μm or more in thickness, and the adhesive layer is a layer made of an acrylic polymer pressure-sensitive adhesive having a thickness of 30 μm or more.

  According to the present invention, the adhesive layer is a layer made of an acrylic polymer pressure-sensitive adhesive having a thickness of 30 μm or more, and any of the pair of plastic members bonded together by the adhesive layer has a thickness of 50 μm or more. Even when foreign matter or bubbles are mixed between a pair of plastic members (for example, a lenticular lens member and a supporting member), deformation based on the foreign matter and the like is absorbed by the adhesive layer having a thickness of 30 μm or more. It is difficult for deformation and defects based on the above.

  In the light diffusing sheet of the present invention, the adhesive layer preferably contains light diffusing fine particles, and the light diffusing fine particles are contained in the adhesive layer in an amount of 1 to 50% by weight. Is preferred. According to this invention, since the adhesive layer includes the light diffusing fine particles, the adhesive layer has a light diffusing function. As a result, as in the case of a light diffusion sheet corresponding to a single light source, even if it is difficult to contain a sufficient amount of light diffusing fine particles in the member because the thickness of the plastic member bonded with the adhesive layer is thin, A desired light diffusion function can be exhibited as the entire light diffusion sheet.

  In the light diffusion sheet of the present invention, (1) a Fresnel lens portion is formed on one of the pair of plastic members, and (2) a lenticular lens portion is formed on either one of the pair of plastic members. Or (3) any one of the pair of plastic members is a front plate located on the foreground on the viewer side of the projection television. According to these inventions, various light diffusion sheets applicable as a transmissive screen can be configured.

  In order to achieve the above object, a transmission screen of the present invention has the light diffusion sheet of the present invention. According to this invention, it becomes a transmission type screen without an appearance defect and an image defect.

  The method for producing a light diffusing sheet of the present invention for achieving the above object is a method for producing a light diffusing sheet in which the thickness of each of a pair of plastic members bonded via an adhesive layer is 50 μm or more, An adhesive layer made of an acrylic polymer adhesive with a thickness of 30 μm or more is formed on one plastic member of a pair of plastic members, the other plastic member is bonded via the adhesive layer, and then pressed It is characterized by defoaming. According to the present invention, since a pair of plastic members are bonded together via an adhesive layer made of an acrylic polymer pressure-sensitive adhesive having a thickness of 30 μm or more, defoaming is performed between the adhesive layer and the plastic member. Even when bubbles are mixed, deformation based on the mixed foreign matter or the like is absorbed by the adhesive layer having a thickness of 30 μm or more, and the plastic member is unlikely to be deformed or defective based on the foreign matter or the like.

  As described above, according to the light diffusion sheet of the present invention, the lens pitch formed on the light diffusion sheet is set to a fine pitch of, for example, 0.3 mm or less, as in the case of using a pixel display type single light source as a light source. In the case of manufacturing a light diffusion sheet without moire by laminating thin members, the manufactured light diffusion sheet is image defect because it is difficult to cause defects or deformations due to bubbles or foreign matters that may be mixed at the time of bonding. And a light diffusing sheet without appearance defects.

  Such a light diffusing sheet of the present invention uses the light diffusing sheet of the present invention as a constituent member of a transmissive screen of, for example, a projection television, so that a clear image without image defects and appearance defects is projected on the transmissive screen. be able to.

  Hereinafter, the light diffusion sheet, the manufacturing method thereof, and the transmission screen of the present invention will be described in detail with reference to the drawings.

(Light diffusion sheet)
FIG. 1 is a schematic cross-sectional view showing an example of the light diffusion sheet of the present invention. As shown in FIG. 1, the light diffusion sheet 10 of the present invention has a pair of plastic members 11 and 12 bonded together via an adhesive layer 13, and at least of the pair of plastic members 11 and 12 and the adhesive layer 13. One has a light diffusion function. The characteristic features are that the pair of plastic members 11 and 12 each have a thickness T ₁₁ and T ₁₂ of 50 μm or more, and the adhesive layer 13 has a thickness T _{13 of} 30 μm or more made of an acrylic polymer adhesive. It is in having.

  Examples of specific embodiments of the light diffusion sheet of the present invention include lenticular lens sheets 20 and 30 (see FIGS. 2 and 3) in which a lenticular lens portion is formed on one of a pair of plastic members. A light diffusion sheet 51b (see FIG. 5B) in which a Fresnel lens portion is formed on one of a pair of plastic members can be given.

(Adhesive layer)
First, the adhesive layer which is one of the features of the present invention will be described in detail.

  The adhesive layer 13 is formed of an acrylic polymer pressure-sensitive adhesive and acts to bond a pair of opposed plastic members 11 and 12 as shown in FIG. The acrylic polymer adhesive is made by copolymerizing acrylic monomers, and the polymerization method may be an organic solvent type that polymerizes in an organic solvent, or an emulsion that polymerizes in water using a surfactant. Although the type may be used, an organic solvent type is preferably used.

  Since the acrylic polymer which is the base of the acrylic polymer pressure-sensitive adhesive exhibits tackiness by itself, a so-called tackifier is not required. A monomer constituting such an acrylic polymer is usually composed of three components including an adhesive component, an aggregating component, and a modifying component. As the adhesive component, C2 or higher alkyl esters such as ethyl acrylate, butyl acrylate, octyl acrylate and the like can be used, but C4 to C10 alkyl acrylates are suitable. As the aggregating component, copolymerizable monomers such as lower alkyl alkyl acrylates, methacrylic acid alkyl esters, and vinyl acetate are used. As the modifying component, one having a copolymerizable functional group such as acrylic acid or acrylamide is used.

  The adhesive layer 13 is formed by adhering an adhesive sheet made of an acrylic polymer adhesive to one surface of one plastic member of the pair of plastic members 11 and 12. The light diffusing sheet of the present invention is formed by pressing and adhering with a nip roll while placing another plastic member on the formed adhesive layer 13, and then pressurizing and defoaming. At this time, the nip roll pressurization condition, the pressure defoaming condition, and the like are arbitrarily set depending on the adhesion state and the state of the foam or foreign matter.

  As a method of providing the adhesive layer 13 on the plastic member, for example, it is convenient to use an adhesive sheet with a release sheet. By using such a pressure-sensitive adhesive sheet, an adhesive layer made of an acrylic polymer pressure-sensitive adhesive can be easily transferred and formed on one plastic member.

The thickness _{T 13} of the adhesive layer 13 is 30μm or more. Adhesive layer 13 made of 30μm or more thick T ₁₃ has the advantage that hardly deformed by foreign matter mixed into the bonding step occurs. The upper limit of the thickness _{T 13} of the adhesive layer 13, from the viewpoint of cost, is about 100 [mu] m.

  The adhesive layer 13 made of an acrylic polymer pressure-sensitive adhesive usually has a hardness measured by a Fisher ultra-micro hardness meter within a range of 0.1 GPa or more and 1 GPa or less. The adhesive layer 13 showing a value within such a range is soft, and even when bubbles and foreign matter are mixed, the adhesive layer itself can absorb the bubbles and foreign matter. As a result, it is possible to prevent the plastic member from being deformed based on the bubbles and foreign matters.

  The adhesive layer 13 may contain a light diffusing material such as light diffusing fine particles. Since the adhesive layer 13 containing the light diffusing material has a light diffusing function, the light diffusing property can be controlled without including the light diffusing material in the plastic members 11 and 12 to be bonded. As a result, on the condition that the thickness of 50 μm or more that achieves the effects of the present invention is satisfied, the thickness of the plastic member can be made thinner than before, and a thin light diffusion sheet can be easily produced. This is a case where the plastic member bonded with the adhesive layer is thin, such as a light diffusion sheet corresponding to a single light source, and it is difficult to contain a sufficient amount of light diffusing fine particles in the plastic member. Also, there is an advantage that a desired light diffusion function can be imparted to the entire light diffusion sheet.

  The light diffusing material that can be contained may be a light diffusing material such as light diffusing fine particles generally used for optical sheets. Styrene resin fine particles, silicone resin fine particles, acrylic resin fine particles, MS resin (methacrylic- Styrene copolymer resin) Organic fine particles such as fine particles, barium sulfate fine particles, glass fine particles, aluminum hydroxide fine particles, calcium carbonate fine particles, silica (silicon dioxide) fine particles, titanium oxide fine particles, glass beads, and other inorganic fine particles. These 1 type (s) or 2 or more types can be contained in the resin.

  When light diffusing fine particles are used as the light diffusing material, the maximum particle size of the light diffusing fine particles is preferably not more than one third of the thickness of the adhesive layer. The light diffusing fine particles having such a particle size do not cause a problem such as unevenness even if contained in the adhesive layer, and there is no adverse effect such as a foreign matter in the present application. Note that the maximum particle size of the light diffusing fine particles varies depending on the thickness of the adhesive layer. Increasing the thickness of the light diffusing fine particles allows the inclusion of the light diffusing fine particles having a larger particle size.

  The concentration of the light diffusing fine particles contained in the adhesive layer is adjusted according to the light diffusing performance imparted to the adhesive layer, and can usually be adjusted within a range of 1 wt% to 50 wt%. If the concentration of the light diffusing fine particles is less than 1% by weight, the light diffusing performance may not be exhibited. If the concentration exceeds 50% by weight, the light diffusing fine particles in the acrylic polymer pressure-sensitive adhesive forming the adhesive layer may be used. Dispersibility of the resin becomes poor, and problems such as precipitation may occur in a solvent (for example, a solvent such as toluene, ethyl acetate, or alcohol) when coating a polymer such as acrylic or urethane. The preferable concentration of the light diffusing fine particles is 30% by weight or more and 50% by weight or less, although it varies depending on the degree of the light diffusing performance carried on the adhesive layer.

(Element)
Next, the pair of plastic members 11 and 12 bonded together through the adhesive layer 13 will be described. Examples of the pair of plastic members 11 and 12 include various members that can be bonded to each other by the adhesive layer 13 to form the light diffusion sheet 10, and may be thermoplastic plastic or thermosetting plastic. There may be. The present invention is characterized in that each of the pair of plastic members 11 and 12 has a thickness T ₁₁ and T ₁₂ of 50 μm or more. If the thickness of any one of the plastic members 11 and 12 is less than 50 μm, the rigidity (for example, rigidity evaluated by the elastic modulus) for achieving the object of the present invention is not sufficient, and the adhesion having a thickness of 30 μm or more is not sufficient. When bonding is performed via the layer 13, there is a risk of deformation due to foreign matter mixed during the bonding.

  FIG. 2 is a schematic cross-sectional view showing an example of an embodiment of the light diffusion sheet of the present invention. This light diffusion sheet is a lenticular lens sheet 20 in which a lenticular lens portion is formed on one of a pair of plastic members, and the lenticular lens member 21 having a thickness of 50 μm or more and the support member 22 are bonded as described above. The layer 23 is bonded together. Since the adhesive layer 23 has already been described in detail, only the characteristic part will be described here.

  As shown in FIG. 2, the lenticular lens member 21 includes a cylindrical lenticular lens portion 24 that extends in the vertical direction on the light source side surface, and a light absorbing portion that includes a black stripe layer 27 that also extends in the vertical direction on the opposite surface. And a BS pattern composed of a light transmission portion located between the black stripe layers 27. The base film 25, the photosensitive adhesive layer 26, and the black stripe layer 27 are provided in this order from the lenticular lens portion 24 side.

  The lens shape of the lenticular lens portion 24 is designed so that parallel light incident perpendicularly to the lenticular lens member surface is condensed on the surface of the light transmission portion or in the vicinity thereof. The lenticular lens portion 24 is formed with a fine pitch corresponding to a recent single light source. As a material for forming the lenticular lens portion 24, a radiation curable resin, specifically, an acrylate resin such as urethane, polyester or epoxy is used. Material is used. The lenticular lens part 24 is formed by applying the radiation curable resin to the shaping mold of the lenticular lens part 24 and irradiating the substrate film 25 placed thereon with radiation (for example, ultraviolet rays or electron beams). It can be carried out by a method of curing the radiation curable resin. The base film 25 at this time is, for example, a PET film having a thickness of 50 μm or more and 250 μm or less. Thereafter, the sheet is peeled from the shaping mold to produce a lenticular lens member intermediate body in which the lenticular lens portion 24 is formed.

  Thereafter, a radical-polymerizable photosensitive adhesive layer 26 is laminated on the lenticular lens non-formation surface, which is the flat surface side of the produced lenticular lens member intermediate, and irradiated with ultraviolet rays of parallel light from the lenticular lens part formation surface side. Then, the photosensitive adhesive layer 26 is exposed, and the condensing portion of the photosensitive adhesive layer 26 is cured by a so-called self-alignment method using the function of the lenticular lens itself. At this time, the part cured by exposure loses the adhesiveness, and the non-light-collecting part that is not exposed maintains the adhesiveness. Next, carbon transfer paper is laminated on the photosensitive adhesive layer 26, and then the transfer release layer of the carbon transfer paper is peeled off, and the black stripe layer 27 is transferred to the non-light-condensing portion to form a BS pattern. Thus, the film-like lenticular lens member 21 can be produced. In this embodiment, the thickness of the lenticular lens member 21 of 50 μm or more means that at least the thickness of the base film 25 is 50 μm or more.

  The support member 22, which is another plastic member, is not particularly limited as long as the support member 22 has rigidity enough to support the lenticular lens member 21. However, the thickness is at least 50 μm or more, and usually a thickness of 1 A resin plate within a range of ˜3 mm is preferably used. Examples of the material of the resin plate include transparent resins made of acrylic resin, styrene resin, polyester resin, polycarbonate resin, acrylic-styrene copolymer resin, and the like. The support member 22 is manufactured by performing press molding, injection molding, casting molding, or the like on these resins.

  The lenticular lens member 21 and the support member 22 which are a pair of plastic members obtained as described above are bonded together via the adhesive layer 23 transferred from the adhesive sheet. Specifically, on the BS pattern forming surface of the lenticular lens member 21 or on the support member 22, a layer made of an acrylic polymer pressure-sensitive adhesive formed on the pressure-sensitive adhesive sheet is transferred, and another layer is provided thereon. The plastic member is pressed and bonded with a nip roll, and then defoamed under pressure. Thus, the lenticular lens sheet 20 shown in FIG. 2 is formed.

  FIG. 3 is a schematic cross-sectional view showing another example of the embodiment of the light diffusion sheet of the present invention. This light diffusing sheet is a lenticular lens sheet 30 in which a lenticular lens portion is formed, and a lenticular lens member 31 having a thickness of 50 μm or more and a support member 32 are bonded together via the adhesive layer 33 described above. It will be. Since the adhesive layer 23 has already been described in detail like the one shown in FIG. 2, only the characteristic part will be described here.

  As shown in FIG. 3, the lenticular lens member 31 has a light absorbing portion 36. The light absorbing portion 36 extends in the vertical direction on the surface on the viewer side serving as the light exit surface, and has a constant pitch in the horizontal direction. It is formed with. The light absorbing portion 36 is formed by filling a large number of substantially V-shaped grooves 36 with a low refractive index resin containing light absorbing particles, and constitutes a low refractive index portion 35.

  In the lenticular lens member 31, the portion other than the groove 36 constitutes the high refractive index portion 34, and the inclined surface forming the groove 36 serves as an interface between the low refractive index portion 35 and the high refractive index portion 34. The inclined surface is constituted by a first inclined surface 37 and a second inclined surface 38, and these inclined surfaces 37, 38 function as a light guide that totally reflects substantially parallel light deflected by the Fresnel lens sheet. Further, the low refractive index portion 35 containing the light absorbing resin acts to improve the contrast by absorbing stray light in the transmissive screen and absorbing outside light.

  The lenticular lens member 31 is also formed at a fine pitch corresponding to a recent single light source, as with the lenticular lens member 21 described above. Acrylic resin materials such as epoxy and epoxy are used. The lenticular lens member 31 is formed by applying the above-mentioned radiation curable resin on a mold roll in which the inverted shape of the groove 36 is formed, and bonding a base film thereon, and then applying radiation (for example, ultraviolet rays) from the base film side. Or an electron beam) and the radiation curable resin is cured. The base film at this time is, for example, a PET film having a thickness of 50 μm or more and 250 μm or less. Thereafter, the sheet is peeled from the mold roll to produce the lenticular lens member 31.

  The support member 32, which is another plastic member, is not particularly limited as long as the support member 32 is rigid enough to support the lenticular lens member 31, as in the case of the support member 22. A resin plate having a thickness of 50 μm or more and usually having a thickness of 1 to 3 mm is preferably used. The material and manufacturing method are the same as in the case of the support member 22 described above.

  The lenticular lens member 31 and the support member 32, which are a pair of plastic members obtained as described above, are bonded together with an adhesive layer 33 interposed therebetween. Specifically, a layer made of an acrylic polymer pressure-sensitive adhesive formed on the pressure-sensitive adhesive sheet is provided on the groove forming surface of the lenticular lens member 31 or on the support member 32, and another layer placed thereon. Two plastic members are bonded together while being pressed with a nip roll, and then defoamed under pressure. In this way, the lenticular lens sheet 30 shown in FIG. 3 is produced.

  Next, the function of the light diffusion sheet of the present invention will be described.

  In the light diffusion sheet of the present invention, at least one of the pair of plastic members 11 and 12 and the adhesive layer 13 has a light diffusion function. As a light diffusion sheet having a light diffusion function, (1) the viewing angle is expanded in the horizontal direction for substantially parallel light deflected by, for example, a Fresnel lens sheet like the lenticular lens unit 24 shown in FIGS. (2) One or two or more of the pair of plastic members and the adhesive layer may contain the above-described light diffusing fine particles, or (3) An uneven surface may be formed on the light surface or the light exit surface.

  Further, the light exit surface of the light diffusion sheet may have various functional layers. Usually, for example, an antireflection layer, a low reflection layer, a hard coat layer, an antistatic layer, an antiglare layer, or an antifouling layer is formed on the outer surface (the outermost surface on the viewer side) of the support member shown in FIGS. A layer having one or more functions selected from a polarizing filter layer, an electromagnetic wave shielding layer, and the like is provided according to the purpose. The support member provided with such a functional layer functions as a front plate located on the forefront of the projection television viewer side, and also serves as the support members 22 and 32 shown in FIGS. 2 and 3, for example. The front plate may contain a light diffusing material as necessary.

  As described above, in the light diffusion sheet of the present invention, the adhesive layer is a solid layer having a thickness of 30 μm or more made of an acrylic polymer pressure-sensitive adhesive. Even so, deformation due to foreign matter is unlikely to occur. Furthermore, since the thickness of the opposing plastic member is 50 μm or more, the member has a certain value or more of rigidity. As a result, even when a foreign substance is mixed during bonding, deformation due to the mixed foreign substance hardly occurs.

  Such a light diffusing sheet is a light diffusing sheet that does not cause moire by laminating thin members having a fine pitch of 0.3 mm or less, for example, as in the case of using a pixel display type single light source as a light source. In this case, there is an advantage that defects and deformations based on bubbles and foreign matters that may be mixed during bonding are less likely to occur. As a result, the manufactured light diffusing sheet becomes a light diffusing sheet free from image defects and appearance defects.

(Transparent screen)
4 and 5 are schematic perspective views showing examples of the transmission screen of the present invention. The transmission screen of the present invention has the light diffusion sheet of the present invention described above. Specifically, a Fresnel lens part that deflects light from a single light source into substantially parallel light is provided on the image light source side, and a lenticular lens part that adjusts the viewing angle by diffusing the deflected substantially parallel light on the observer side. It is to be prepared.

  More specifically, the transmissive screen 50 shown in FIG. 4 includes a refractive type circular Fresnel lens sheet 40 having a Fresnel center in the sheet surface, and a light diffusion sheet 20 of the present invention having a cylindrical lens on one side (FIG. 2). For example). A transmission screen 51a shown in FIG. 5 (A) has a refractive type circular Fresnel lens sheet 40 having a Fresnel center in the sheet surface, and a large number of substantially V-shaped grooves on one side. The light diffusion sheet 30 (refer FIG. 3) of this invention which has the low-refractive-index part (light absorption part) which consists of resin which contains a light absorptive particle in the inside is provided. Further, the transmission type screen 51b shown in FIG. 5B has a total reflection type circular Fresnel lens sheet 52 that does not have a Fresnel center in the sheet surface, and a large number of substantially V-shaped grooves on one side. Further, the light diffusion sheet 30 (see FIG. 3) of the present invention having a low refractive index portion (light absorption portion) made of a resin containing light absorbing particles in the groove is bonded via an adhesive layer 53. It will be. In the transmission type screen 51b of FIG. 5B, when the Fresnel lens sheet 52 and the light diffusion sheet 30 are viewed as “a pair of plastic members”, when the adhesive layer 53 has the characteristics of the present invention, The entire transmission type screen becomes a light diffusion sheet.

  The Fresnel lens sheet used in the transmissive screen of the present invention is formed with a fine pitch corresponding to a recent single light source, and the formation material thereof is the same radiation as described in the above lenticular lens member. A curable resin, specifically, an acrylate resin material such as urethane, polyester, or epoxy is used. Such a Fresnel lens sheet is formed by applying the radiation curable resin to the shaping mold of the Fresnel lens and further irradiating the substrate film placed thereon with radiation (for example, ultraviolet rays or electron beams) to cure the radiation. This can be done by curing the mold resin. Thereafter, the sheet is peeled from the shaping mold to produce a Fresnel lens sheet.

(Rear projection display)
FIG. 6 is a configuration diagram showing an example of a rear projection display device equipped with a transmission screen having the light diffusion sheet of the present invention as a constituent member. FIG. 6A is an example of a rear projection display device equipped with a transmissive screen having a circular Fresnel lens with the Fresnel center in the sheet plane, and FIG. 6B shows the Fresnel center outside the sheet surface. 2 is an example of a rear projection display device equipped with a transmissive screen having a total reflection type circular Fresnel lens.

  The rear projection display devices 60a and 60b are provided with transmissive screens 51a and 51b having the light diffusing sheet of the present invention as constituent members on the front side windows, and are relatively thin housings 61a and 61b. A light source 62 is disposed at the bottom, and mirrors 63a and 63b for reflecting light from the light source 62 toward the transmissive screens 51a and 51b are disposed on the inner surfaces of the rear walls of the casings 61a and 61b. The light source 62 at this time is a single tube type single light source using LCD (Liquid Crystal Display) or DLP (Digital Light Processing).

  Since the light diffusing sheet of the present invention is used as a constituent member for the transmissive screens 51a and 51b, a clear image having no appearance defect can be projected on the transmissive screen.

  Next, a more detailed description will be given with specific examples.

Example 1
As a light diffusion sheet, a lenticular lens sheet with a support member having a lenticular lens portion on one side was prepared.

First, a urethane acrylate resin, which is an ultraviolet curable resin, is applied on a shaping mold of a lenticular lens portion that has been processed so that the lens pitch is 0.05 mm and the lens thickness is 25 μm, and the thickness is applied to the mold. A 50 μm PET film (Toyobo Co., Ltd., A-4100, tensile elastic modulus: 400 kg / mm ² ) was placed, and after the UV curable resin was stretched with a rubber nip roll, UV curing was performed by irradiating UV from above. The mold resin was cured. Thereafter, the sheet was peeled off from the shaping mold to produce a lenticular lens member intermediate in which a lenticular lens portion was formed. The tensile elastic modulus is a value measured according to JIS K7113.

  Thereafter, a radical polymerizable photosensitive adhesive layer is formed on the lenticular lens part non-formation surface, which is the flat surface side of the produced lenticular lens member intermediate, and irradiated with ultraviolet rays of parallel light from the lenticular lens part formation surface side. Then, the photosensitive adhesive layer was exposed, and the condensing portion of the photosensitive adhesive layer was cured by a so-called self-alignment method using the function of the lenticular lens itself. At this time, the adhesiveness was lost in the portion cured by exposure, and the non-light-condensing portion not exposed was maintained in adhesiveness. Next, carbon transfer paper was laminated on the photosensitive adhesive layer, and then the transfer release layer of the carbon transfer paper was peeled off, and the black stripe layer was transferred to the non-light-collecting portion to form a BS pattern. Thus, a film-like lenticular lens member was produced.

Next, an acrylic plate having a thickness of 2 mm (tensile elastic modulus: 300 kg / mm ^{2, the} measurement method is the same as described above) is prepared as a rigid sheet-like support member, and the acrylic plate is placed on the acrylic plate. An acrylic polymer pressure-sensitive adhesive layer is transferred from a pressure-sensitive adhesive sheet formed on a release sheet by a 30 μm-thick polymer adhesive layer (manufactured by Toyo Packing Co., Ltd., trade name: A pressure-sensitive adhesive), Then, the lenticular lens member prepared in advance was placed on the adhesive layer and bonded together while being pressed with a nip roll, to finally produce a 50-inch size (1130 mm × 650 mm) lenticular lens sheet.

  The hardness of the formed adhesive layer was 0.3 GPa as a result of measurement with a Fisher ultra-micro hardness meter (manufactured by Fisher Instrument Co., Ltd., trade name: FISHERSCOPE H100VP-HCU X-Yprog).

  The lenticular lens sheet of Example 1 was not defoamed during pressure bonding between the adhesive layer and the lenticular lens member. However, in Example 4 described later, the lenticular lens sheet was bonded while pressure degassing was performed. went.

(Examples 2 to 4 and Comparative Examples 1 and 2)
In Example 1, (a) the thickness of the PET film used when producing the lenticular lens member intermediate, and (b) pressure defoaming treatment conditions (50 ° C., 0.4 MPa for 1 hour) (C) Examples 2 to 4 and Comparative Examples 1 and 2 according to the light diffusion sheet of the present invention were the same as Example 1 except that the thickness of the adhesive layer was changed as shown in Table 1. A lenticular lens sheet was prepared.

(Appearance evaluation)
Each of the lenticular lens sheets of Examples 1 to 4 and Comparative Examples 1 and 2 and the Fresnel lens sheet obtained as follows are arranged in the manner shown in FIG. -It was set on the screen fixing frame of a 50-inch projection television equipped with a DLP light source (HLM 5065W, manufactured by Samsung Electronics Co., Ltd.). The appearance at that time was visually observed, and the appearance defect due to the inclusion of foreign matter was evaluated. Moreover, the image defect based on bubble mixing observed the screen surface in TV ON state visually, and evaluated the image defect by bubble mixing. The results are shown in Table 1. From the results shown in Table 1, a lenticular lens sheet having a good appearance could be obtained within the scope of the present invention.

  The Fresnel lens sheet constituting the transmissive screen used for the evaluation was coated with a urethane acrylate curable resin similar to the above on a shaping mold for forming the Fresnel lens portion, and a thickness of 2 mm was formed thereon. An acrylic sheet was placed, pressed with a rubber nip roll, cured by irradiation with ultraviolet rays, and then peeled off from the mold.

It is a schematic cross section which shows an example of the light-diffusion sheet of this invention. It is a schematic cross section which shows an example of embodiment of the light-diffusion sheet of this invention. It is a schematic cross section which shows another example of embodiment of the light-diffusion sheet of this invention. It is a model perspective view which shows an example of the transmission type screen provided with the light-diffusion sheet of this invention. It is a model perspective view which shows the other example of the transmission type screen provided with the light-diffusion sheet of the other form of this invention. It is a block diagram which shows the example of the rear projection type display apparatus with which a transmissive screen is mounted | worn. It is explanatory drawing of the conventional manufacturing method of a light-diffusion sheet.

Explanation of symbols

10, 20, 30 Light diffusing sheet 11, 12 member 13, 23, 33 Adhesive layer 21, 31 Lenticular lens member 22, 32 Support member 24 Lenticular lens part 25 Base film 26 Photosensitive adhesive layer 27 Black stripe layer 34 Light transmission Part 36 Light absorption part 37, 38 Total reflection surface 40 Fresnel lens sheet 50, 51a Transmission type screen 51b Transmission type screen (light diffusion sheet)
52 Fresnel lens sheet (Fresnel lens sheet member)
53 The thickness of the adhesive layer 60a, 60b rear projection display device 61a, 61b housing 62 single light source 63a, 63b mirror 64 image light 65 emitted light _{T 11, T 12, T 21} , T 21, T 31, T 32 member T ₁₃ , T ₂₃ , T ₃₃ Adhesive layer thickness

Claims (8)

  A light diffusing sheet having a pair of plastic members bonded via an adhesive layer, wherein at least one of the pair of plastic members and the adhesive layer has a light diffusing function, wherein each of the pair of plastic members is 50 μm or more A light diffusing sheet having a thickness, wherein the adhesive layer is a layer made of an acrylic polymer pressure-sensitive adhesive and having a thickness of 30 μm or more.   The light diffusion sheet according to claim 1, wherein the adhesive layer includes light diffusing fine particles.   The light diffusion sheet according to claim 2, wherein the light diffusing fine particles are contained in the adhesive layer in an amount of 1 to 50% by weight.   The light diffusion sheet according to claim 1, wherein a Fresnel lens portion is formed on one of the pair of plastic members.   The light diffusion sheet according to any one of claims 1 to 3, wherein a lenticular lens portion is formed on one of the pair of plastic members.   4. The light diffusing sheet according to claim 1, wherein one of the pair of plastic members is a front plate positioned on a foreground on the viewer side of the projection television.   A transmissive screen comprising the light diffusion sheet according to claim 1.   A method of manufacturing a light diffusing sheet in which a thickness of each of a pair of plastic members bonded via an adhesive layer is 50 μm or more, wherein an acrylic polymer adhesive is applied to any one of the pair of plastic members. A method for producing a light diffusing sheet, comprising: forming an adhesive layer having a thickness of 30 μm or more, bonding another plastic member through the adhesive layer, and then depressurizing and depressurizing.

Images