JP2005250097A - Optical member and its manufacturing method, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member capable of suppressing shrinkage stress of a polarizing plate in heating and humidifying environment even when the member is made large-sized to be adapted to a large-sized flat panel which is applied to the flat panel of a liquid crystal cell or the like and formed by sticking the polarizing plate on a light-transmissive supporting substrate. <P>SOLUTION: The optical member 1 is formed by sticking at least the polarizing plate 11 on the light-transmissive supporting substrate 12 and applied to the flat panel, and the optical member is curved in one direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical member applied to a flat panel, in which at least a polarizing plate is bonded to a light-transmitting support substrate, and a method for manufacturing the same. The present invention also relates to a liquid crystal display device using an optical member, an organic EL display device, an image display device such as a PDP.

  Conventionally, polarizing plates have been used in image display devices such as liquid crystal display devices. In the liquid crystal display device, the polarizing plates are disposed on both sides of the liquid crystal cell. The polarizing plate easily shrinks and deforms in a humidified / heated environment, and when a retardation plate or a liquid crystal cell is in close contact with the polarizing plate, it is difficult to maintain a good display quality by applying a large stress to the polarizing plate. . In particular, a stretched polyvinyl alcohol film dyed with iodine, which is used for award, tends to shrink and deform. The polarizing plate can be bonded to the liquid crystal cell with an adhesive or the like, or can be disposed separately.

  When the polarizing plate is bonded to a liquid crystal cell, a retardation plate or the like with an adhesive, an adhesive force to the liquid crystal cell or the like is required. Since the polarizing plate is more rigid than other optical films, the adhesive force is good. This characteristic is effective as a protective function for liquid crystal display measures. In addition, the polarizing plate is required to have removability when the bonding fails. However, the polarizing plate has a good adhesive force but is difficult to peel and remove. In particular, with the increase in screen size, the probability of bonding failure has also increased, and the load on the liquid crystal cell substrate at the time of peeling removal from the increase in the adhesion area due to the increase in size has increased at an accelerated rate. Since the thinning of the substrate glass of the liquid crystal cell is also progressing and the resistance to stress is reduced, the peelability cannot be satisfied. In addition, when a polarizing plate is bonded to a liquid crystal cell, a phase difference plate, or the like with an adhesive, there is an attempt to use a flexible material that does not easily transmit stress as an adhesive to relieve stress due to shrinkage deformation. However, such an adhesive is liable to cause another problem such as poor adhesion and easy peeling.

  On the other hand, the following examples are known as a liquid crystal display device in which a liquid crystal cell and a polarizing plate are separately arranged. For example, in a projection type liquid crystal display device, it is known that a polarizing plate is bonded to a light-transmitting support substrate in order to suppress the visibility of foreign matter adhering to the surface of the polarizing plate, and this is separated from the liquid crystal cell via an air gap. (See Patent Document 1). Moreover, in a projection type liquid crystal display device, in order not to directly transmit the heat of the polarizing plate that absorbs irradiation heat from a powerful light source to the liquid crystal cell, the polarizing plate is bonded to a light-transmitting support substrate, and this is a liquid crystal cell. Those separately placed via an air gap are known (see Patent Document 2, Patent Document 3, Patent Document 4, etc.). Furthermore, biting foreign matter when the polarizing plate is bonded to the liquid crystal cell is removed, or deterioration of the display quality due to abnormal cell gap of the liquid crystal cell due to stress when peeling and re-bonding the polarizing plate is suppressed. In order to do this, a polarizing plate is bonded to a light-transmitting support substrate, and this is separated from the liquid crystal cell via an air gap (see Patent Document 5).

  The technique described in the patent document is effective in a projection type liquid crystal display device using a relatively small liquid crystal cell. However, when the configuration in which the polarizing plates are separated and applied is applied to a large-sized liquid crystal display device, trouble occurs in details. For example, in Patent Document 5, since the polarizing plate and the retardation plate are bonded to the support substrate, the stress of the polarizing plate is transmitted to the retardation plate. Such a defect is not particularly problematic when the polarizing plates are bonded together, but it becomes a problem when the polarizing plates contract in a heated / humidified environment. Further, such a defect is not considered as a problem in a small display device, but cannot be ignored in a large liquid crystal display device. That is, even when a polarizing plate having the same level of contraction rate is used, the absolute amount of contraction increases in proportion to the screen size, and the shear stress applied to the peripheral edge increases. In particular, in recent years, it has been a serious problem until a large screen TV using a liquid crystal display device is commercialized. Further, as in Patent Document 2, a method of holding a polarizing plate alone in a suspended state without bonding to a support substrate is possible with a small liquid crystal display device, but difficult with a large screen.

  Thus, as the screen size of the liquid crystal display device increases, the polarizing plate also increases, and the problem of shrinkage stress under the humidification / heating environment is inevitable. Due to this shrinkage stress, a phase difference is generated and non-uniform display unevenness occurs in the screen. This problem becomes more serious as the screen size increases, which has been an obstacle to maintaining good display quality.

In addition, when the polarizing plate is bonded to the supporting substrate, it is necessary to suppress the deformation of the supporting substrate against the contraction stress of the polarizing plate. Since the polarizing plate has different axial directions depending on the design of the liquid crystal cell, the contraction direction of the polarizing plate cut out in a rectangular shape is not necessarily parallel to the long side / short side, and twisting may occur in an oblique direction. The bending and twisting of the support substrate must be sufficiently suppressed.
JP-A-6-258637 Japanese Utility Model Publication No. 1-140516 Japanese Patent Laid-Open No. 3-51881 Japanese Patent Application Laid-Open No. 9-189962 JP-A-11-52355

  The present invention is an optical member applied to a flat panel such as a liquid crystal cell, and the optical member is obtained by bonding a polarizing plate to a light-transmitting support substrate, and is sized to accommodate a large flat panel. An object of the present invention is to provide an optical member capable of suppressing the shrinkage stress of a polarizing plate in a heating / humidification environment even when the size of the polarizing plate is increased. Moreover, it aims at providing the manufacturing method of the said optical member.

  Another object of the present invention is to provide an image display device using the optical member.

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the optical member shown below, and have completed the present invention.

That is, the present invention is an optical member applied to a flat panel in which at least a polarizing plate is bonded to a light-transmitting support substrate,
The optical member relates to an optical member that is curved in one direction.

  In the optical member of the present invention, a polarizing plate is bonded to a light-transmitting support substrate. However, since the support substrate is already curved in one direction, the shrinkage stress of the polarizing plate in a heating / humidifying environment. Can be suppressed. Further, even when shrinkage stress is generated in the polarizing plate, since the support substrate is curved in advance, further deformation can be suppressed. The optical member can provide a panel structure that does not affect the image quality even when applied to a flat panel. Moreover, since the said optical member can suppress a shrinkage stress also when the size of a polarizing plate becomes large, it can fully respond also to a large-sized flat panel.

  Moreover, since the optical member of the present invention has a curved structure, it has excellent impact resistance. In order to ensure impact resistance with a polarizing plate bonded to a flat base material as in the past, the flat base material requires a considerable thickness and weight, but according to the optical member of the present invention, a curved structure Thus, impact resistance is obtained by a relatively thin structure. In a liquid crystal display device, the liquid crystal cell needs to maintain a cell gap in units of μm, and if an abnormality occurs in the cell gap, the display quality may be deteriorated, but the optical member of the present invention is excellent in impact resistance. Therefore, display quality deterioration due to impact can be prevented. As described above, since the optical member of the present invention is excellent in impact resistance, such a large screen can be protected from an unexpected impact even when applied to a liquid crystal display device such as a large home screen TV. Moreover, since the optical member of this invention has impact resistance, it can suppress a crack and scattering.

  Furthermore, the optical member of the present invention is arranged separately on a flat panel such as a liquid crystal cell, and the material can be easily separated and collected. In particular, when large-screen TVs are distributed in large quantities, it is advantageous in terms of high maintainability such as separation at the time of disposal and easy replacement of damaged parts due to impact or the like.

  As the optical member, a material in which an optical layer other than the polarizing plate is further laminated can be used. Examples of the other optical layer include a retardation plate, a reflective polarizer, and an antireflection layer. These optical layers can be provided on the surface of the light transmissive support substrate or the polarizing plate constituting the optical member, or can be provided between the light transmissive support substrate and the polarizing plate. In the present invention, even when these optical layers are provided, since the stress shrinkage of the optical member (polarizing plate) is small, the display quality of the liquid crystal display device and the like can be maintained well.

  In the optical member, a bending length (L1) in a direction in which the optical member is bent, and a space length (L2) between the flat surface and the convex portion when the optical member is arranged in a convex shape on the flat surface. The ratio (L1 / L2) is preferably 10 to 1000. As the ratio increases, the stress resistance and impact resistance increase, but the overall thickness increases and the surrounding reflection increases. On the other hand, when the said ratio becomes small, stress resistance will fall. Therefore, the ratio is selected within a range where the required stress resistance and impact resistance are satisfied and the thickness can be reduced. The ratio (L1 / L2) is more preferably 50-100.

  The ratio (L1 / L2) advantageously has the ratio in the above range when the flat panel has a large screen, for example, a 20-inch screen size or larger or a wide 20-inch screen size or larger. In the optical member, a phase difference is generated due to shrinkage stress, and non-uniform display unevenness occurs in the screen. In particular, display unevenness tends to occur locally in the screen when the screen size is larger than the above. Therefore, the display quality tends to be lowered. Therefore, it is advantageous to have the ratio above the screen size described above.

  It is preferable that a reinforcing member is disposed at the curved end of the optical member. By arranging the reinforcing member at the curved end portion, the strength of the optical member having a curved structure is remarkably improved, and the stress resistance is improved. When such a structure is provided, deformation of the support substrate due to deformation of the polarizing plate can be further suppressed, and stable display quality can be ensured. Such a structure is also suitable from the viewpoint of protecting a flat panel such as a liquid crystal cell from external impact. Further, since the IPS mode screen tends to be weak against stress, it can be suitably applied to the IPS mode screen.

  The optical member is applied to a flat panel, but the flat panel is preferably applied to a liquid crystal cell. The liquid crystal cell is preferably applied to a liquid crystal cell having a retardation plate on its surface. The retardation plate can be directly formed on the surface of the liquid crystal cell as well as being bonded with an adhesive or the like. Since the retardation plate is arranged separately from the optical member (polarizing plate), it does not receive contraction stress, and even in a heating / humidifying environment, the display quality is not affected at all by the optical member. Can be secured.

  The present invention also relates to the method for manufacturing an optical member, comprising the step of fixing the shape by bending the light transmissive support substrate after the polarizing plate is bonded to the light transmissive support substrate.

  The present invention also relates to a method for producing the optical member, comprising the step of bonding a polarizing plate to a curved and light-transmitting support substrate.

  The present invention also relates to an image display device comprising at least a flat panel and the optical member. Application to a flat panel surface having a retardation plate is preferred. As the image display device, application to a liquid crystal display device using a liquid crystal cell as a flat panel is effective.

  In the image display device or the liquid crystal display device, the optical member is placed on a viewing side surface of the flat panel or the liquid crystal cell so that a direction in which the optical member is curved is a viewing horizontal direction of the flat panel or the liquid crystal cell. It is preferable that they are arranged. The viewing surface side of the screen of the image display device or the liquid crystal display device is preferably arranged in the horizontal direction in which the optical member is curved in order to suppress reflection of indoor lighting.

  The present invention will be described below with reference to the drawings. FIG. 1 is an example of a perspective view of the optical member 1, and a polarizing plate 11 is bonded to a light transmissive support substrate 12. In FIG. 1, the polarizing plate 11 is bonded to the convex side of the light transmissive support substrate 12, but the polarizing plate 11 may be bonded to the concave side of the light transmissive support substrate 12. From the viewpoint of suppressing the deformation and shrinkage of the polarizing plate over time, a structure in which the polarizing plate 11 is bonded to the convex side of the light transmissive support substrate 12 as shown in FIG. 1 is preferable.

  As shown in FIG. 1, the optical member 1 is curved in one direction. In FIG. 1, the curved direction is a horizontal direction on the drawing. The curvature of the optical member 1 has a curvature in a specific uniaxial direction represented by a part of the cylindrical side surface (horizontal direction in FIG. 1). On the other hand, the shape has no curvature in the orthogonal direction (vertical direction in FIG. 1). This is because a flat film such as the polarizing plate 11 is bonded to the surface having curvature in the biaxial direction. The curved surface shape curved in the optical member 1 may be a circular or elliptical part or a higher order aspherical shape.

  In the optical member 1, the curved direction may be either the short side or the long side. The curved direction depends on the contraction direction / axial direction of the polarizing plate, the aspect ratio of the screen of the image display device such as the liquid crystal display device to which the optical member 1 is applied, the allowable overall thickness, and the like. Can be selected in a timely manner.

  The optical member 1 preferably has a ratio (L1 / L2) of 10 to 1000. The bending length (L1) in the direction in which the optical member 1 is curved, and the space length (L2) between the flat surface and the convex portion when the optical member 1 is arranged in a convex shape on the flat surface are shown in FIG. As shown in

  FIG. 3 is an example of a perspective view of a structure in which the reinforcing member 2 is disposed at the curved end portion of the optical member 1.

  FIG. 4 is an example of a cross-sectional view of a liquid crystal display device in which the optical member 1 is disposed on both surfaces of the liquid crystal cell LC as viewed from above. In FIG. 4, retardation plates 3 are provided on both side surfaces of the liquid crystal cell. A backlight BL is disposed as a light source. In FIG. 4, it arrange | positions so that the convex surface which the optical member 1 curves may become the outer side with respect to liquid crystal cell LC. The optical member 1 can be disposed on the flat panel so that either the curved convex surface or the concave surface is on the outside, but it is difficult to transmit an impact due to an external force to the flat panel. As shown in FIG. 2, it is preferable to arrange the optical member 1 so that the curved convex surface is on the outside. In particular, when it is arranged on the viewing side of the liquid crystal cell, the optical member 1 is preferably arranged so that the curved convex surface is on the outside. Moreover, in FIG. 4, the optical member 1 is arrange | positioned at the visual recognition side surface so that the direction where the said optical member 1 curves may become the visual recognition horizontal direction of liquid crystal cell LC.

  In addition, as shown in FIG. 4, since a space | gap arises between liquid crystal cell LC and the optical member 1, it is preferable to give an antireflection process to the surface of the optical member 1 of a space | gap side, and the flat panel surface. . By providing an antireflection layer on the surface (air gap side), the effective transmittance is improved, display quality problems such as contrast reduction due to interface reflection can be reduced, and good display quality can be obtained. Further, it is desirable to perform an antistatic treatment on the gap surface, because it can suppress the adsorption of foreign matters during cell assembly and improve the yield.

  The optical member can be combined with other layers (for example, a reflective polarizer). The optical member combined with the reflective polarizer is disposed on the backlight side with respect to the liquid crystal cell. The reflective polarizer may be disposed on either side of the polarizing plate or the support substrate, and can be sandwiched therebetween. However, when the support substrate is sandwiched between the polarizing plate and the reflective polarizer, the contrast is not affected, but the amount of transmitted light is reduced, which is not preferable. In the optical member combined with the reflective polarizer, the polarizing plate is disposed closer to the liquid crystal cell than the reflective polarizer.

  When the optical member is disposed in the liquid crystal cell, the polarizing plate side of the optical member is disposed on the liquid crystal cell side, or in the optical member in which the reflective polarizer is combined, the polarizing plate and the reflective polarizer side are disposed on the liquid crystal cell side. In the case of arrangement, the phase difference value of the support substrate may not be considered. In this case, a function as a diffusion plate or a function as a prism sheet can be incorporated into the support substrate in the optical member combined with the reflective polarizer. Alternatively, a diffusion plate or a prism sheet may be bonded to the side surface of the backlight of the support substrate, and if necessary, an end portion may be spot-bonded or sandwiched between support claws.

  On the other hand, when the support substrate side of the optical member is disposed on the liquid crystal cell side, or when the support substrate is sandwiched between the polarizing plate and the reflective polarizer in an optical member combined with a reflective polarizer, the retardation of the support substrate Value matters. This is because coloring and luminance unevenness are visually recognized by the phase difference. Even if the support substrate has a retardation value, it cannot be visually recognized if its slow axis is arranged perpendicular or parallel to the polarization axis of the polarizing plate, but the versatility is lost because the polarization axis direction changes depending on the design of the liquid crystal cell. Therefore, it is not preferable. From the viewpoint of coloring and luminance unevenness, the support substrate preferably has a front retardation value of preferably 20 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less. With such a phase difference, large coloring and luminance unevenness are not visually recognized. The phase difference value is a value measured by an automatic birefringence meter KOBRA21D manufactured by Oji Scientific Instruments.

  Moreover, a light-scattering material can also be used for the support substrate. If diffusibility is imparted to the support substrate, it is not necessary to separately place other diffusion plate materials. However, if the support substrate side of the optical member is disposed on the liquid crystal cell side, or if the support substrate is sandwiched between a polarizing plate and a reflective polarizer in an optical member combined with a reflective polarizer, depolarization due to scattering is eliminated. It becomes a problem. In this case, the decrease in the degree of polarization of transmitted light is 1% or less, desirably 0.5% or less, and more desirably 0.2% or less. The degree of polarization is a value measured by DOT3 manufactured by Murakami Color Research Co., Ltd.

  Hereinafter, constituent members of the optical member and image display devices such as a liquid crystal display device will be described.

  Although the polarizer itself can also be used as the polarizing plate, generally, a polarizing plate having a transparent protective film on one side or both sides of the polarizer is generally used.

  The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymer films such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. Examples thereof include polyene-based oriented films such as those obtained by adsorbing volatile substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride and the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed with dyeing after iodine. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  The transparent protective film can be provided as a coating layer made of a polymer or a laminate layer of the film. As the transparent polymer or film material for forming the transparent protective film, an appropriate transparent material can be used, but a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property and the like is preferably used. Examples of the material for forming the transparent protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as cellulose diacetate and cellulose triacetate, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile, Examples thereof include styrene polymers such as styrene copolymers (AS resins), polycarbonate polymers, and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of polymers that form the transparent protective film. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing an unsubstituted phenyl and a thermoplastic resin having a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.

  Moreover, it is preferable that a protective film has as little color as possible. Therefore, Rth = [(nx + ny) / 2−nz] · d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a retardation value in the film thickness direction of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. On the other hand, a protective film such as triacetylcellulose has a large retardation value Rth in the thickness direction and has a problem of coloring, but contains an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the resin composition to be used, those having a thickness direction retardation value Rth of 30 nm or less can be used, and coloring can be almost eliminated. In addition, when providing a protective film in the both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. As the adhesive, an adhesive made of an aqueous solution is usually used.

  The polarizing plate is produced by bonding the transparent protective film and the polarizer using the adhesive. The adhesive may be applied to either the transparent protective film or the polarizer, or to both. After the bonding, a drying process is performed to form an adhesive layer composed of a coating dry layer. Bonding of a polarizer and a transparent protective film can be performed with a roll laminator or the like. The thickness of the adhesive layer is not particularly limited, but is usually about 0.1 to 5 μm.

  As the material for the light transmissive support substrate, the same material as that used for the transparent protective film can be used. The material is preferably an epoxy polymer, norbornene polymer, cycloolefin polymer, or acrylic polymer because of its low retardation value. The thickness of the light-transmitting support substrate is not particularly limited, but is preferably about 0.5 to 10 mm, and more preferably 1 to 5 mm from the viewpoints of strength, workability, weight, transmittance, and the like.

  The method for producing the optical member of the present invention is not particularly limited. For example, (1) after bonding the polarizing plate and the light transmissive support substrate, the light transmissive support substrate is curved to fix the shape. Can be manufactured. Moreover, (2) It can manufacture by bonding a polarizing plate to the light-transmitting support substrate formed into a curve.

  In the manufacturing method described above, the method of bending the light-transmitting support substrate is, for example, a method in which the light-transmitting support substrate is brought into contact with a mold having a predetermined shape, heated to be bent, and then cooled and fixed. Examples thereof include a method of injection molding a plastic material into a mold having a predetermined shape, a method of polymerizing and curing an ultraviolet ray or a thermosetting material in a predetermined mold, and the like.

  In addition, an adhesive is usually used for bonding the light-transmitting support substrate and the polarizing plate. The pressure-sensitive adhesive is not particularly limited, but for example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, an acrylic pressure-sensitive adhesive or the like that is excellent in optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and is excellent in weather resistance, heat resistance, and the like.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient. If diffusibility is imparted to the adhesive layer material, separate placement of other diffusion plate materials is unnecessary. In this case as well, the decrease in the degree of polarization of transmitted light is 1% or less, desirably 0.5% or less, and more desirably 0.2% or less.

  The pressure-sensitive adhesive may be directly applied to the light-transmitting support substrate and / or the polarizing plate, and can be formed in advance as an adhesive layer on the light-transmitting support substrate and / or the polarizing plate. The attachment of the adhesive layer can be performed by an appropriate method. For example, a pressure-sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a single solvent or a mixture of appropriate solvents such as toluene and ethyl acetate is prepared, and the casting method is used. A method of attaching directly on a polarizing plate or an optical film by an appropriate development method such as coating or coating method, or forming an adhesive layer on a separator according to the above and transferring it to a polarizing plate or a light-transmitting support substrate. The method of wearing is raised.

  The adhesive layer can also be provided as an overlapping layer of different compositions or types. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

  Note that, when the light-transmitting support substrate and the polarizing plate are bonded to each other, the surface of the light-transmitting support substrate can be appropriately subjected to an easy adhesion process such as a saponification process, a corona process, or an anchor process.

  As the reinforcing member disposed at the curved end of the optical member, a plate-shaped member is usually used. The thickness is not particularly limited, but is preferably about 0.2 to 10 mm, and more preferably 0.5 to 7 mm. Examples of the material of the reinforcing member include metals such as iron, aluminum, and stainless steel, epoxy resins, acrylic resins, and ABS resins. The shape of the reinforcing member is not particularly limited, but is appropriately determined in consideration of stability when placed on a flat panel.

  The reinforcing member is arranged at the curved end so that the curved shape of the optical member can be fixed. As a fixing method, a method of adhering with an adhesive such as an epoxy resin or an isocyanate resin, or a difference between the curved end of the reinforcing member. Examples of the method include a method of inserting a reinforcing member into the insertion portion, and a method of using both of them. Further, when the curved end portion of the optical member is inserted into the insertion portion of the reinforcing member, the inserted curved end portion is arranged to be a non-display area when the optical member is applied to a flat panel. Is preferred.

  In the optical member, another optical layer can be laminated on the polarizing plate in practical use. The other optical layer may be laminated on either the polarizing plate side or the light transmissive support substrate. Moreover, although lamination | stacking may only be arrange | positioned, it can also bond together by the adhesion layer. These layers can be formed individually or can be laminated together as a layer having a composite function.

  Other optical layers are not particularly limited. For example, liquid crystal display devices such as a reflection plate, a semi-transmission plate, a phase difference plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film are formed. One optical layer or two or more optical layers may be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. It is preferable to use a wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film (reflection polarizer) on the polarizing plate.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one side of the polarizing plate via a transparent protective film or the like, if necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. Moreover, the transparent protective film contains fine particles so as to have a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. The transparent protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it, and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by transparent the metal by an appropriate method such as a vacuum evaporation method, an ion plating method, a sputtering method, or a deposition method It can be performed by a method of attaching directly to the surface of the protective film.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  Specific examples of the retardation plate include a birefringent film obtained by stretching a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, and polyamide. And an alignment film of a liquid crystal polymer, and a liquid crystal polymer alignment layer supported by a film. The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of the liquid crystal layer, viewing angle, and the like. What laminated | stacked the phase difference plate and controlled optical characteristics, such as phase difference, etc. may be used.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. As such a viewing angle compensation phase difference plate, for example, a retardation film, an alignment film such as a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate is used. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetylcellulose film. A plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. As shown (3M, DBEF, etc.), cholesteric liquid crystal polymer alignment film or alignment liquid crystal layer supported on a film substrate (Nitto Denko, PCF350, Merck, Transmax, etc.) Alternatively, any suitable one may be used, such as one that reflects either one of the clockwise circularly polarized light and transmits other light.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that emits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer. However, from the viewpoint of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation plate that functions as a quarter-wave plate for monochromatic light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation plate, for example, a retardation plate functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation plates.

  In addition, a cholesteric liquid crystal layer having a structure in which two layers or three or more layers are superposed with a combination of those having different reflection wavelengths can obtain a layer that reflects circularly polarized light in a wide wavelength range such as a visible light region. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

An example of the anisotropic reflective polarizer used as the brightness enhancement film is a reflective grid polarizer. As a reflective grid polarizer, a metal grid reflective polarizer (see US Pat. No. 6,288,840, etc.) that finely processes metal to produce reflected polarized light even in the visible light region, and metal fine particles in a polymer matrix. And a stretched one (see JP-A-8-184701, etc.). An example of the brightness enhancement film is an anisotropic scattering polarizer. An example of the anisotropic scattering polarizer is DRP made by 3M (see US Pat. No. 5,825,543). Examples of the brightness enhancement film include a polarizing element that can perform polarization conversion in one pass. For example, the one using smectic C ^* is mentioned (see JP 2001-201635 A). An anisotropic diffraction grating can be used as the brightness enhancement film.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of the liquid crystal display device and the like can be improved. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  When the other optical layers described above are bonded together with an adhesive layer, the same adhesive as exemplified in the bonding of the light-transmitting support substrate and the polarizing plate can be used. The thickness of the adhesive layer is the same as described above.

  In the present invention, each layer such as the optical member and the adhesive layer is treated with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. It may also be one having an ultraviolet absorbing ability by a method such as

  The optical member (polarizing plate) of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, the optical member, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point used, and it can apply according to the past. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which the optical member is arranged on one side or both sides of the liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the said optical member can be installed in the one side or both sides of a liquid crystal cell. When the optical members are provided on both sides, they may be the same or different. Moreover, it is preferable to provide a phase difference plate on one side or both sides of the liquid crystal cell. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. The optical member (polarizing plate) of the present invention can also be applied to an organic EL display device. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light-emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Optical member)
The surface of a 3 mm thick acrylic substrate (Sumipex manufactured by Sumitomo Chemical Co., Ltd., front phase difference of about 3 nm) was subjected to easy adhesion treatment (saponification treatment). This was used as a support substrate. A polarizing plate with a pressure-sensitive adhesive (TEG1465DUHCARC2 manufactured by Nitto Denko) was bonded to the surface of the acrylic substrate subjected to easy adhesion treatment to obtain an optical member (supporting substrate integrated polarizing plate). The processed substrate size was 1000 mm × 1000 mm, the size was 37 inches diagonal, and the aspect ratio was 16: 9, and a product corresponding to a diagonal 39 inches size was cut out from the optical member with a carbon dioxide laser. The size after cutting is 860 mm × 480 mm. The obtained optical member was curved in the major axis direction with the polarizing plate surface as a convex surface. The bending length (L1) is 860 mm.

  Next, as shown in FIG. 3, the curved end of the optical member was fixed with a reinforcing member. As the reinforcing member, an acrylic resin having a thickness of 5 mm was used. The reinforcing member is provided with an insertion portion of the curved end portion of the optical member. The curved end portion is inserted into the insertion portion and fixed with an epoxy adhesive. The optical member thus obtained was strong and strong against twisting and bending, and was difficult to deform even when stress was applied to the central convex portion. The curvature radius of the obtained curved surface was about 1300 mm, and the space length (L2) between the flat surface and the central convex portion was about 10 mm. The ratio (L1 / L2) was about 86.

(Liquid crystal display device)
As the liquid crystal cell, a liquid crystal cell taken out from a commercially available liquid crystal television (37-inch wide screen) was used. A negative phase difference plate (viewing angle correction phase difference plate) produced under the following conditions was bonded to both surfaces of the liquid crystal cell.

  The retardation plate is as follows. Liquid weight monomer (BASF, LC242) 88 parts by weight, chiral agent (BASF, LC756) 12 parts by weight and photoreaction initiator (Ciba Specialty Chemicals, Irgacure 907) 2 parts by weight with methyl ethyl ketone A solution was prepared so that This solution was applied onto a 75 μm thick polyethylene terephthalate film so that the thickness when dried was about 4 μm, and the liquid crystal was oriented at 130 ° C. after air drying. Further, ultraviolet irradiation (10 mW / square cm × 1 minute) was performed to obtain a retardation plate. For attaching the phase difference plate to the liquid crystal cell, the adhesive material NO. 7 (thickness 25 μm) was used for bonding.

  The optical member obtained above was arranged on both sides (viewing side and backlight side) of the liquid crystal cell as shown in FIG. The bending direction of the optical member was set to be the visual horizontal direction of the liquid crystal cell. The obtained liquid crystal display device was rigid and easy to handle on either side. The liquid crystal display device is a large panel with a diagonal of about 1 m, but it was easy to disassemble, remove foreign matter, and separate.

(Performance evaluation)
The liquid crystal display device was allowed to stand at a temperature of 80 ° C. for 250 hours, and then the display quality was confirmed. There was no phase difference fluctuation of the retardation plate due to the concentration of shrinkage stress in the peripheral part of the polarizing plate, and no polarization loss was observed. According to JIS R 3206-1979, a 227 g steel ball was dropped from a height of 1 m on the viewing side optical member, but the liquid crystal cell was not broken.

Example 2
An antireflection film (an ARC2-HC-TAC film made by Nitto Denko) was bonded to the liquid crystal cell surface side (support substrate side) of the optical member used on the viewing side in Example 1. On the other hand, a similar antireflection film was also bonded to the liquid crystal cell surface side (support substrate side) of the optical member used on the backlight side. Further, a reflective polarizer (manufactured by 3M, DBEF) was bonded to the polarizing plate side of the optical member used on the backlight side so that the polarization transmission axis was the same as the transmission axis of the polarizing plate. The brightness of the obtained liquid crystal display device was improved by about 40%. The performance evaluation was performed in the same manner as in Example 1, and similar results were obtained.

Comparative Example 1
A commercially available liquid crystal television (37-inch wide screen) was used as the liquid crystal display device. In this liquid crystal display device, a polarizing plate and a retardation plate are bonded to a liquid crystal cell. The liquid crystal display device was evaluated for performance in the same manner as in Example 1. When the display quality was confirmed after being allowed to stand at a temperature of 80 ° C. for 250 hours, the polarization loss due to the fluctuation of the retardation value of the retardation plate was slightly observed due to the contraction stress concentration in the peripheral part of the polarizing plate. In addition, when a 227 g steel ball is dropped from a height of 1 m according to JIS R 3206-1979 with respect to the optical member on the viewing side, a failure such as a cell gap abnormality of the liquid crystal cell occurs and the display quality is maintained. I could not do it.

Comparative Example 2
In Example 1, when producing the optical member used on the viewing side, the curvature direction (viewing horizontal direction) of the optical member was also given a curvature on the short axis side (which is the screen vertical direction in the liquid crystal display device). The optical member on the viewing side was prepared in the same manner as Example 1 except for the above. In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that the optical member on the viewing side was used. The liquid crystal display device has a wide vertical reflection range, and the reflection of the light source located on the ceiling hinders visibility.

It is an example of the perspective view of the optical member of this invention. It is an example of sectional drawing at the time of arranging the optical member of the present invention in the plane. It is an example of the optical member which has arrange | positioned the reinforcement member of this invention. It is an example of sectional drawing which looked at the liquid crystal display device of the present invention from the upper part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical member 11 Polarizing plate 12 Light transmissive support substrate 2 Reinforcing member 3 Phase difference plate LC Liquid crystal cell BL Backlight

Claims (15)

An optical member applied to a flat panel, at least a polarizing plate is bonded to a light transmissive support substrate,
The optical member is curved in one direction.   The optical member according to claim 1, wherein an optical layer other than the polarizing plate is further laminated on the optical member.   The optical member according to claim 2, wherein the other optical layer is a retardation plate.   4. The optical member according to claim 2, wherein the other optical layer is a reflective polarizer.   5. The optical member according to claim 2, wherein the other optical layer is an antireflection layer.   The ratio (L1 / L2) between the bending length (L1) in the direction in which the optical member is bent and the space length (L2) between the flat surface and the convex portion when the optical member is arranged in a convex shape on the flat surface. ) Is 10 to 1000, The optical member according to any one of claims 1 to 5.   The optical member according to claim 1, wherein a reinforcing member is disposed at a curved end portion of the optical member.   The optical member according to any one of claims 1 to 7, wherein the flat panel to which the optical member is applied is a liquid crystal cell.   9. The optical member according to claim 8, further comprising a retardation plate on the surface of the liquid crystal cell.   It is a manufacturing method of the optical member in any one of Claims 1-6, Comprising: After bonding a polarizing plate to a light transmissive support substrate, the process of curving a light transmissive support substrate and fixing a shape. A method for manufacturing an optical member, comprising:   The method for manufacturing an optical member according to claim 1, further comprising a step of bonding a polarizing plate to the light-transmitting support substrate that is curved and formed.   An image display device comprising at least a flat panel and the optical member according to claim 1.   The image display device according to claim 12, further comprising a retardation plate on a surface of the flat panel.   14. The liquid crystal display device according to claim 12, wherein the flat panel is a liquid crystal cell. The said optical member is arrange | positioned on the visual recognition side surface of a flat panel or a liquid crystal cell so that the direction in which the said optical member is curving becomes the visual recognition horizontal direction of a flat panel or a liquid crystal cell. The image display device according to claim 12 or 13, or the liquid crystal display device according to claim 14.

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