Image display device and method for manufacturing optical body

Abstract

To provide an image display device and a method for manufacturing an optical body that have a high durability and can suppress reduction of contrast by emission of external light.SOLUTION: In order to achieve the above objective, the image display device according to the present invention includes an optical body 10 with a micro prism structure 11 in one surface of the body, the micro prism structure 11 of the optical body 10 being formed on an image display surface side O of the image display device, the micro prism structure 11 including a plurality of prisms 12 in the shape of triangular waves with a vertex 12C protruding from a formation surface 13 to the image display surface side O, and the prisms 12 in the shape of triangular waves being asymmetrical triangular wave types of prisms in which angles α and β of two inclined surfaces 12A and 12B extending from the formation surface 13 are different.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an image display device and an optical body that are highly durable and capable of suppressing a decrease in contrast caused by exposure to external light. [Background technology]

[0002] Image display devices such as liquid crystal displays and organic light-emitting diode displays, as well as devices equipped with an image display function such as smartphones and game consoles, are sometimes exposed to strong external light, and it is desirable to suppress the loss of contrast and deterioration of image quality (occurrence of color unevenness, ghosting, etc.) caused by light reflection. As a technique for suppressing a decrease in contrast caused by irradiation with external light, for example, a technique of providing an anti-glare film or an anti-reflection film on the image display surface of the device is known.

[0003] For example, Patent Document 1 discloses a technique for suppressing the generation of reflected light by providing an anti-reflection film having a fine uneven structure (moth-eye structure) with an average pitch equal to or smaller than the visible light wavelength band. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-98304 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the conventional technology of providing an anti-glare film or an anti-reflection film on the image display surface, it has not been possible to obtain sufficient image contrast when the image display device is placed in an environment exposed to strong external light. Even when an anti-reflection film with a moth-eye structure as in Patent Document 1 is used, sufficient image contrast cannot be obtained when the film is placed in an environment exposed to strong external light. Furthermore, because the fine concave-convex structure is a delicate structure, it is necessary to improve the durability against external pressure.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide an image display device and an optical body manufacturing method that are highly durable and capable of suppressing a decrease in contrast due to exposure to external light. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the inventors have found that by providing an optical body having a microprism structure formed on its surface and optimizing the shape and arrangement direction of the microprism structure, it is possible to reliably deflect reflected light caused by external light irradiation in an upward or downward direction as viewed by the observer, thereby obtaining good image contrast, and further, because the microrhythm structure is stronger than the fine motheye structure described above, the durability of the optical body can also be improved.

[0008] The present invention has been made based on the above findings, and the gist of the present invention is as follows. (1) An image display device comprising an optical body having a microprism structure formed on one surface thereof, a microprism structure of the optical body is formed on the image display surface side of the image display device, The image display device is characterized in that the microprism structure is formed by forming a plurality of triangular wave prisms having apexes protruding from a forming surface toward the image display surface, and the triangular wave prisms are asymmetric triangular wave prisms in which the inclination angles of the two sloping surfaces extending from the forming surface are different. With the above-described configuration, the durability of the optical body can be increased, and a decrease in contrast caused by irradiation with external light can be suppressed. (2) The image display device described in (1) above, characterized in that the inclined surfaces constituting the triangular wave prism include a first inclined surface having an inclination angle from the forming surface of 10° or more, and a second inclined surface having an inclination angle from the forming surface of 60° or more greater than that of the first inclined surface. (3) The image display device described in (1) or (2) above, characterized in that the triangular wave-shaped prisms in the microprism structure all extend in the horizontal direction of the image display device and the optical body is arranged so that the first inclined surface is located downward. (4) The image display device according to any one of (1) to (3) above, wherein the triangular wave prisms in the microprism structure have an arrangement pitch of 5 to 50 μm. (5) The image display device according to any one of (1) to (4) above, wherein the triangular wave prisms in the microprism structure all extend continuously. (6) A method for producing an optical body provided in the image display device according to any one of (1) to (5) above, comprising the steps of: A step of preparing a mold having a triangular wave-shaped groove formed therein; applying a release coating to the surface of the mold groove; applying a curable resin onto the release coating applied to the mold; a step of disposing a base film on the curable resin and then curing the curable resin; and peeling the laminate of the base film and the curable resin from the mold. A method for manufacturing an optical body, characterized in that the triangular wave groove of the mold comprises a first groove inclined surface having an inclination angle of 10° or more from the horizontal plane, and a second groove inclined surface having an inclination angle of 60° or more greater from the horizontal plane than the first inclined surface. With the above-described configuration, it is possible to obtain an image display device that has high durability and is capable of suppressing a decrease in contrast caused by irradiation with external light. Effect of the Invention

[0009] According to the present invention, it is possible to provide an image display device and an optical body manufacturing method that are highly durable and can suppress a decrease in contrast due to exposure to external light. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing an optical body in an image display device according to an embodiment of the present invention. [Diagram 2] FIG. 1A is an enlarged, schematic cross-sectional view of one embodiment of an optical body in an image display device of the present invention, and FIG. 1B is an enlarged, schematic front view of one embodiment of an optical body in an image display device of the present invention. [Diagram 3] 1 is a cross-sectional view showing a schematic flow of light emitted from an image display element when an optical body in an image display device has a symmetric triangular wave prism structure. FIG. [Figure 4] FIG. 4 is a flow diagram showing an example of a manufacturing process for manufacturing an optical body provided in an image display device according to one embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic perspective view for explaining the configuration of an apparatus used for measuring the regular reflectance of optical body samples of Examples 1 to 3 and Comparative Examples 2 to 5 in the examples. [Figure 6] 1 is a graph showing the reflectance (%) as a function of wavelength for optical body samples of Examples 1 to 3 and Comparative Examples 2 to 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an example of an embodiment of the present invention will be specifically described with reference to the drawings as necessary. FIG. 1 is a perspective view showing one embodiment of an optical body in an image display device of the present invention, FIG. 2(a) is an enlarged schematic cross-sectional view of one embodiment of an optical body in an image display device of the present invention, and FIG. 2(b) is an enlarged front view of one embodiment of an optical body in an image display device of the present invention. In addition, for the convenience of explanation, the components disclosed in the drawings may be shown diagrammatically at a scale and in a shape different from the actual ones.

[0012] <Image display device> First, an embodiment of an image display device of the present invention will be described. As shown in FIG. 1, the image display device of the present invention includes an optical body 10 having a microprism structure 11 formed on one surface. In the image display device of the present invention, as shown in FIG. 1 and FIG. 2(a), the microprism structure 11 of the optical body 10 is formed on the image display surface side O of the image display device, The microprism structure 11 is characterized in that a plurality of triangular wave-shaped prisms 12 having an apex 12C protruding from a forming surface 13 toward the image display surface side O are formed, and the triangular wave-shaped prisms 12 are asymmetric triangular wave-type prisms in which the angles α and β of two inclined surfaces 12A and 12B extending from the forming surface 13 are different.

[0013] In the optical body 10 in the image display device of the present invention, the microprism structure 11 is formed on the image display surface side O (the side of the observer who views the image) and the triangular wave-shaped prisms 12 (hereinafter sometimes simply referred to as "prisms") that constitute the microprism structure 11 are the asymmetric triangular wave-type prisms described above.As a result, as shown in Figure 1, most of the reflected light generated from the irradiated external light can be deflected in a direction that is not directly facing the observer (downward in Figure 1), and as a result, a decrease in the contrast of the image from the image display element can be effectively suppressed. Furthermore, as shown in FIG. 2(b), the microprism structure 11 of the optical body 10 has a shape in which triangular wave-shaped prisms 12 extend in the horizontal direction T, and is stronger than a fine uneven structure such as a moth-eye structure, and can achieve high durability even outdoors or in situations where external pressure is applied.

[0014] Here, the microprism structure 11 formed on the formation surface 13 of the optical body 10 is made up of a plurality of prisms 12 each having an apex 12C protruding from the formation surface 13 towards the image display surface O. By forming the microprism structure 11 on the image display surface side O (the side of the observer viewing the image), as shown in Figure 1, most of the reflected light generated from the irradiated external light can be deflected in a direction not directly facing the observer (downward in Figure 1). On the other hand, if the microprism structure 11 is formed on the image display element side I, the image display surface side O (the side of the observer viewing the image) becomes flat, and much of the external light is reflected toward the observer side, resulting in a decrease in image contrast and deterioration of image quality.

[0015] As shown in Figure 2(a), the microprism structure 11 is formed with a plurality of triangular wave-shaped prisms 12, and the triangular wave-shaped prisms 12 are asymmetric triangular wave-type prisms in which the inclination angles α and β of the two inclined surfaces (first inclined surface 12A and second inclined surface 12B) extending from the forming surface 13 are different. Because the angles of the first inclined surface 12A and the second inclined surface 12B that constitute the triangular wave-shaped prism 12 are different, most of the reflected light of the irradiated external light can be deflected in a direction that is not directly facing the observer (downward in Figure 1), and the light from the image display element can be transmitted through the microprism structure 11, allowing most of it to reach the observer.

[0016] 3, when the inclination angles α and β of the first inclined surface 120A and the second inclined surface 120B extending from the formation surface 13 are the same (symmetric triangular wave prism), the reflected light of the irradiated external light can be deflected in a direction not directly facing the observer (upward or downward). However, when the light from the image display element passes through, it is totally reflected in the symmetric triangular wave prism, and the desired transparency cannot be obtained, resulting in inferior image contrast compared to the microprism structure 11 of the present invention consisting of the asymmetric triangular wave prism 12.

[0017] As described above, from the viewpoint of obtaining better image contrast while suppressing degradation in image quality, it is preferable that the inclined surfaces constituting the triangular wave-shaped prism 12 consist of a first inclined surface 12A having an inclination angle α from the forming surface 13 of 10° or more, and a second inclined surface 12B having an inclination angle β from the forming surface 13 that is 60° or more greater than the inclination angle α of the first inclined surface 12A, and it is more preferable that the difference between the inclination angle β of the second inclined surface 12B and the inclination angle α of the first inclined surface 12A is 70° or more.

[0018] Furthermore, from the viewpoint of obtaining better image contrast while suppressing degradation in image quality, the inclination angle α of the first inclined surface 12A of the triangular wave prism 12 is preferably 10° or more, more preferably 15° or more, and more preferably 20° or more. Furthermore, the inclination angle β of the second inclined surface 12B of the triangular wave prism 12 is preferably 70° or more, more preferably 80° or more, and even more preferably 85° or more. For such a prism 12, for example, the inclination angle α of the triangular wave-shaped prism 12 can be 20° and the inclination angle β can be 90°, or the inclination angle α of the triangular wave-shaped prism 12 can be 30° and the inclination angle β can be 100°, or the inclination angle α of the triangular wave-shaped prism 12 can be 35° and the inclination angle β can be 105°.

[0019] Incidentally, the inclination angles α and β of the first inclined surface 12A and the second inclined surface 12B of the prisms 12 may be the same for all the prisms 12, or the inclination angles α and β may be different for each prism 12. However, from the viewpoints of ease of manufacture, prevention of unnecessary reflection, and obtaining better image contrast, it is preferable that all the prisms 12 in the microprism structure 11 have the same inclination angles α and β.

[0020] Furthermore, although there is no particular limitation on the extension direction of each prism 12 in the microprism structure 11, it is preferable that the optical body 10 is arranged so that all of the triangular wave-shaped prisms 12 extend in the horizontal direction T of the image display device and the first inclined surface 12A is positioned downward, as shown in Figures 2(a) and (b). By positioning the optical body 10 so that the first inclined surface 12A of the triangular wave prism 12 is positioned below the observer, as shown in FIG. 1, the incident external light is reflected downward, making it less likely for the reflected light to enter the observer's field of vision, resulting in better image contrast.

[0021] 2(a) and (b), it is preferable that the triangular wave prisms 12 in the microprism structure 11 extend continuously. Since there are no breaks in the triangular wave prisms 12, problems such as lines appearing in images can be more reliably prevented, and since the bulk of the triangular wave prisms 12 is increased, the durability of the glossy body 10 can be further improved.

[0022] The number of triangular wave prisms 12 formed in the microprism structure 11 is not particularly limited, and can be adjusted appropriately depending on the required size of the optical body.

[0023] As shown in FIGS. 2(a) and 2(b), the arrangement pitch A of the triangular wave prisms 12 in the microprism structure 11 is preferably 5 to 50 μm. 10~40μm By setting the arrangement pitch A of the triangular wave prisms 12 to 5 μm or more, better manufacturability (ease of manufacturing the prisms 12) can be obtained, and by setting the arrangement pitch A of the triangular wave prisms 12 to 50 μm or less, interference of reflected light can be prevented, and better image contrast can be obtained.

[0024] 2(a), the microprism structure 11 may be provided with a support portion of the microprism structure 11 (hereinafter referred to as a "base portion 14" of the microprism structure 11) where the triangular wave-shaped prisms 12 of the microprism structure 11 are not formed. By providing the base portion 14 to the microprism structure 11, ease of manufacture can be ensured, the strength of the triangular wave-shaped prisms 12 can be increased, and the durability of the optical body 10 can also be improved.

[0025] Furthermore, the thickness of the base portion 14 of the microprism structure is not particularly limited, but is preferably 0.1 μm or more, and more preferably 1 μm, because by making the thickness of the base portion 14 of the microprism structure 1 μm or more, higher durability can be ensured.

[0026] Here, there is no particular limitation on the material constituting the microprism structure 11. For example, from the viewpoint of moldability of the microprism structure 11, a resin composition that is cured by a curing reaction, such as an active energy ray curable resin composition (a photocurable resin composition, an electron beam curable resin composition) or a thermosetting resin composition, and for example, a resin composition containing a polymerizable compound and a polymerization initiator can be used.

[0027] Examples of the polymerizable compound that can be used include (i) an ester obtained by reacting 2 or more moles of (meth)acrylic acid or a derivative thereof with 1 mole of a polyhydric alcohol, and (ii) an ester obtained from a polyhydric alcohol, a polycarboxylic acid or anhydride thereof, and (meth)acrylic acid or a derivative thereof. Examples of the above (i) include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetrahydrofurfuryl acrylate, glycerin tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, acryloyl monophorin, and urethane acrylate. Examples of the above (ii) include esters obtained by reacting a polyhydric alcohol such as trimethylolethane, trimethylolpropane, glycerin, or pentaerythritol with a polycarboxylic acid or anhydride thereof selected from malonic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, fumaric acid, itaconic acid, or maleic anhydride, and (meth)acrylic acid or a derivative thereof. These polymerizable compounds may be used alone or in combination of two or more.

[0028] Furthermore, in the case where the resin composition is photocurable, examples of the photopolymerization initiator include carbonyl compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzil, benzophenone, p-methoxybenzophenone, 2,2-diethoxyacetophenone, α,α-dimethoxy-α-phenylacetophenone, methylphenyl glyoxylate, ethylphenyl glyoxylate, 4,4'-bis(dimethylamino)benzophenone, 1-hydroxycyclohexyl-phenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and benzoyldiethoxyphosphine oxide; and the like, and one or more of these can be used.

[0029] In the case of electron beam curing, examples of the electron beam polymerization initiator include thioxanthones such as benzophenone, 4,4-bis(diethylamino)benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoyl benzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2 acetophenones such as 1-(4-morpholinophenyl)-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; methylbenzoyl formate, 1,7-bisacridinylheptane, and 9-phenylacridine, among which one or more can be used.

[0030] In the case of thermosetting, examples of the thermal polymerization initiator include organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, t-butyl peroxybenzoate, and lauroyl peroxide; azo compounds such as azobisisobutyronitrile; and redox polymerization initiators in which the organic peroxides are combined with amines such as N,N-dimethylaniline and N,N-dimethyl-p-toluidine.

[0031] These photopolymerization initiators, electron beam polymerization initiators and thermal polymerization initiators may be used alone or in any desired combination. The amount of the polymerization initiator is preferably 0.01 to 10 parts by mass per 100 parts by mass of the polymerizable compound. In this range, the curing proceeds sufficiently, the molecular weight of the cured product becomes appropriate, sufficient strength is obtained, and problems such as coloration of the cured product due to the residue of the polymerization initiator do not occur.

[0032] Furthermore, the resin composition may contain, as necessary, a non-reactive polymer or an active energy ray sol-gel reactive component, and may also contain various additives such as a thickener, a leveling agent, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a solvent, and an inorganic filler.

[0033] The optical body 10 may further include a base material 15 bonded to the microprism structure 11 .

[0034] The base material 15 is not particularly limited as long as it has a certain degree of strength and is transparent, and may be made of any conventional material. For example, the material of the base material 15 may be glass, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC), or the like. In this specification, the term "transparent" means that the transmittance of light having a wavelength in the visible light band (approximately 360 nm to 830 nm) is high, and for example, the transmittance of the light is 70% or more. In one embodiment of the present invention, the study was carried out assuming a PET substrate having a thickness of 125 μm.

[0035] Furthermore, the shape of the substrate 15 is not particularly limited except that it is plate-like (film-like), and the thickness of the substrate 15 is also not particularly limited and can be appropriately selected depending on the conditions required for the optical body 10.

[0036] As shown in FIG. 1, the image display device of the present invention includes the optical body 10, but other configurations are not particularly limited and can be appropriately selected depending on the type of image display device. Moreover, the "image" displayed by the image display device of the present invention includes both still images and moving images.

[0037] For example, when the image display device of the present invention is a liquid crystal display device, an image display element having a light source, a liquid crystal panel, a driving circuit, etc. is provided on the image display element side I of the optical body 10. Also, when the image display device of the present invention is an organic EL display device, an image display element having a power source, electrodes, light emitting elements, etc. is provided on the image display element side I of the optical body 10.

[0038] In the image display device of the present invention, the image display surface side O of the optical body 10 may further be provided with a member such as a protective film or a cover.

[0039] Examples of the image display device of the present invention include liquid crystal display devices, organic EL display devices, as well as in-vehicle display devices such as car navigation systems and speedometers, display devices used outdoors, game consoles, smartphones, and watches.

[0040] <Method of manufacturing an optical body> The method for manufacturing the optical body provided in the image display device of the present invention described above is not particularly limited. For example, as shown in FIG. A step of preparing a mold 20 having a triangular wave-shaped groove 23 formed therein (FIG. 4(a)); A step of applying a release coating 21 to the surface of the groove 23 of the mold 20 (FIG. 4(b)); A step of applying a hardening resin 22 onto the release coating 21 applied to the mold 20 (FIG. 4(c)); A step of disposing a base film 15 on the curable resin 22 and then curing the curable resin 22 (FIG. 4(d)); and a step of peeling off the laminate 10' of the base film 15 and the microprism structure 11 made of the cured resin from the mold 20 (FIG. 4(e)).

[0041] The triangular wave-shaped groove 23 of the mold 20 is characterized by comprising a first groove inclined surface 26A having an inclination angle α' from the horizontal plane of 10° or more, and a second groove inclined surface 26B having an inclination angle β' from the horizontal plane of 60° or more larger than that of the first inclined surface 26A. This ensures that a plurality of triangular wave-shaped prisms 12 are formed, each having an apex 12C protruding from the forming surface 13 toward the image display surface side O, as described above, and that the triangular wave-shaped prisms 12 form a microprism structure 11 having an asymmetric triangular wave-type prism in which the angles α, β of the two inclined surfaces 12A, 12B extending from the forming surface 13 are different.

[0042] Regarding the step of preparing the mold 20, as shown in Fig. 4(a), the groove 23 can be formed by cutting the mold material with a cutting tool 24 or the like to create the mold 20, but it is not always necessary to create a mold, and if a mold 20 already exists, it can be used. Furthermore, the cutting of the mold material can also be performed by a method other than the cutting tool 24 to create the mold.

[0043] In addition, the triangular wave groove 23 of the mold 20 is composed of a first groove inclined surface 26A having an inclination angle α' from the horizontal plane of 10° or more, and a second groove inclined surface 26B having an inclination angle β' from the horizontal plane that is 60° or more greater than that of the first inclined surface 26A, and the inclination angle of the groove can be changed as appropriate depending on the required angles α and β of the inclined surfaces 12A and 12B of the triangular wave prism 12 described above.

[0044] The step of applying the release coating 21 is a step of applying the release coating 21 to the entire surface of the groove 23, as shown in Fig. 4(b). This step has the advantage that it becomes easier to release the laminate 10' from the mold 20, which will be described later. The type of the release coating 21 is not particularly limited, and any conventional release coating can be used as appropriate, such as a fluorine coating.

[0045] The step of applying the hardening resin 22 is a step of applying the hardening resin 22, which is to be the material of the microprism structures 11, to the grooves 23 of the mold 20, as shown in FIG. 4(c). The type of the hardening resin is the same as that described above in the description of the material of the microprism structure 11.

[0046] Regarding the process of hardening the curable resin 22, as shown in FIG. 4(d), a base film 15 is placed on the curable resin 22, and then the curable resin 22 is hardened to form a laminate of the base film 15 and the hardened product of the curable resin 22 (later microprism structure 11). When the base film 15 is placed on the curable resin 22, the curable resin 22 is pressed until it fills all of the grooves 23, as shown in Fig. 4(d), and then cured. The curing conditions, such as ultraviolet light, heat, and moisture, can be appropriately set depending on the type of resin.

[0047] The step of peeling the laminate 10' from the mold 20 is a step of peeling the laminate 10' of the base film 15 and the microprism structure 11 made of a cured resin, as shown in Fig. 4(e). The peeled laminate 10' becomes the above-mentioned optical body 10 as it is or after processing. EXAMPLES

[0048] The present invention will now be described in detail with reference to examples, although the present invention is not limited to the following examples in any way.

[0049] <Examples 1 to 3 and Comparative Examples 1 to 5> As described below, optical bodies were prepared under various conditions, and their optical properties were evaluated. Comparative Example 1 A glass having a thickness of 1 mm was used as a sample of Comparative Example 1.

[0050] Comparative Example 2 A sample of Comparative Example 2 was prepared by providing an AG film (manufactured by Keiwa Co., Ltd.) having an uneven surface on a glass plate having a thickness of 1 mm.

[0051] Comparative Example 3 A sample of Comparative Example 3 was prepared by attaching a multilayer AR film (SiO2 / Nb2O5 / SiO2 / Nb2O5 / PET film, thickness 100 μm) onto a glass substrate using an adhesive film ("PDS1" manufactured by PANAC Corporation).

[0052] Comparative Example 4 The sample for Comparative Example 4 was prepared by attaching a film having a fine uneven structure (moth-eye structure) made of UV-curable acrylic resin (average pitch of unevenness: 200 nm, average height of protrusions: 200 nm) onto a glass substrate via an adhesive layer ("PDS1" manufactured by PANAC Corporation).

[0053] Comparative Example 5 As shown in Figure 3, a symmetrical triangular wave type microprism structure 110 having triangular wave prisms 120 made of UV-cured acrylic resin, all of the inclined surfaces constituting the prisms 120 being at 45° and the average arrangement pitch being approximately 20 μm, was formed on a glass substrate and used as a sample for Comparative Example 5.

[0054] Example 1 As shown in Figure 2(a), the sample used in Example 1 was an asymmetric triangular wave type microprism structure 11 formed on a glass substrate, which had triangular wave prisms 12 made of UV-cured acrylic resin, with the inclination angle α of the first inclined surface 12A of the prism 12 being 20°, the inclination angle β of the second inclined surface 12B being 90°, and the average arrangement pitch being 100 μm.

[0055] Example 2 As shown in Figure 2(a), a microprism structure 11 having triangular wave-shaped prisms 12 made of UV-curable acrylic resin, in which the inclination angle α of the first inclined surface 12A of the prism 12 is 25°, the inclination angle β of the second inclined surface 12B is 90°, and the average arrangement pitch is 50 μm, was formed on a glass substrate and used as a sample for Example 2.

[0056] Example 3 As shown in Figure 2(a), a microprism structure 11 having triangular wave-shaped prisms 12 made of UV-curable acrylic resin, in which the inclination angle α of the first inclined surface 12A of the prism 12 is 30°, the inclination angle β of the second inclined surface 12B is 80°, and the average arrangement pitch is 50 μm, was formed on a glass substrate and used as a sample for Example 3.

[0057] <Evaluation> The laminate samples obtained in each of the Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 1.

[0058] (1) Contrast evaluation The optical body of each sample was placed in front of an LED backlight diffuse light source (backlight panel for iPhone 3 LCD). For the samples of Comparative Examples 4 and 5 and Examples 1 to 3, the optical body was placed so that the fine uneven structure or prism structure faced the display surface side (observer side). In addition, for the samples of Examples 1 to 3, the optical body was set so that all of the triangular wave-shaped prisms in the fine uneven structure extended in the horizontal direction and the first inclined surface was positioned downward. First, with the LED backlight diffuse light source turned off, external light from a white LED was irradiated at maximum light intensity, and the characteristics of the reflected light (brightness of external light reflection, color of external light reflection: x, color of external light reflection: y) were measured using a luminance meter (manufactured by Topcon Corporation). Thereafter, the LED backlight diffuse light source was turned on, the panel color was set to white, and the brightness of the light from the panel was measured using a luminance meter (manufactured by Topcon). Then, the contrast ratio (luminance of light from LED backlight diffuse light source / luminance of reflected external light) was calculated from the obtained luminance of reflected external light and the luminance of light from the diffused LED backlight light source. The measurement and calculation results of the optical properties of each sample are shown in Table 1.

[0059] [Table 1]

[0060] The results in Table 1 show that when the samples of the optical bodies of Examples 1 to 3 were used, the contrast was significantly improved compared to when the samples of the comparative examples were used. It can be seen that when the sample of Comparative Example 1 is used, the reflection of external light is large and the contrast ratio is low. Also, when the sample of Comparative Example 2 is used, it can be seen that, although it is better than Comparative Example 1 due to the effect of the AG structure, the reflection of external light cannot be sufficiently suppressed. Furthermore, when the samples of Comparative Examples 3 and 4 are used, although the effect of the anti-reflection treatment can be seen to some extent, when strong external light is irradiated, the brightness of the reflected external light is high and high contrast is not obtained. In addition, when the sample of Comparative Example 5 is used, the apex angle of the triangular wave prism is 90°, so it is possible to deflect the reflection of external light like the samples of Examples 1 to 3, but it is considered that the brightness is deteriorated because the light from the OLED panel is totally reflected inside the prism. In addition, it is found that the reflection of external light is also totally reflected, and sufficient contrast is not obtained. Moreover, it was found from the results in Table 1 that when the samples of the optical bodies of Examples 1 to 3 were used, the reflected chromaticity was also kept neutral, and good image display performance was also maintained.

[0061] (2) Spectral reflectance measurement The optical bodies of the samples of Examples 1 to 3 and Comparative Examples 2 to 5 were irradiated with light from a high-intensity LED lamp under the conditions shown in FIG. 5, and the regular reflectance (%) according to the wavelength (nm) of the external light was measured. For the samples of Comparative Examples 4 and 5 and Examples 1 to 3, the optical body was installed so that the fine uneven structure or prism structure faced the display surface side (brightness measurement camera side). In addition, for the samples of Examples 1 to 3, the optical body was set so that the triangular wave-shaped prisms in the fine uneven structure all extended in the horizontal direction and the first inclined surface was positioned downward, as shown in Fig. 5. The measurement results are shown in Fig. 6.

[0062] From the results in FIG. 6, it can be seen that when the samples of the optical bodies of Examples 1 to 3 are used, reflected light due to external light can be deflected, and so regular reflection can be reduced to nearly zero. On the other hand, it is understood that when the samples of the optical bodies of the respective comparative examples were used, the regular reflectance was higher than in Examples 1 to 3. Furthermore, although not shown, when a fingerprint was left on the optical body of each sample of Examples 1 to 3 and Comparative Examples 2 to 5, the scattering effect due to the AG structure decreased in the optical body of the sample of Comparative Example 2, and the optical bodies of the samples of Comparative Examples 3 and 4 changed the light interference conditions, resulting in an increase in reflectance. On the other hand, in the case of the optical body samples of Examples 1 to 3, the reflectance did not increase significantly even after the fingerprint was left on them. [Industrial Applicability]

[0063] According to the present invention, it is possible to provide an image display device and an optical body manufacturing method that are highly durable and can suppress a decrease in contrast due to exposure to external light. [Explanation of symbols]

[0064] 10 Optical body 10' Laminate 11 Microprism structure 12 Triangular prism 12A first slope, 12B second slope 13 Formation surface 14 Base section 15 Substrates, substrate films 20 Mold 21 Anti-reflection structure 22 Curing resin 23 Mold groove 23A first groove slope, 23B first groove slope 24 bytes 100 optical body 110 Microprism structure 120 Triangular prism α is the inclination angle of the first slope, β is the inclination angle of the second slope α': inclination angle of the first groove slope, β': inclination angle of the second groove slope

Claims

1. An image display device comprising an optical body having a microprism structure formed on one surface thereof, a microprism structure of the optical body is formed on the image display surface side of the image display device, The image display device is characterized in that the microprism structure is formed by forming a plurality of triangular wave-shaped prisms having apexes protruding from a forming surface toward the image display surface, and the triangular wave-shaped prisms are asymmetric triangular wave-type prisms in which the inclination angles of the two sloping surfaces extending from the forming surface are different.

2. 2. The image display device according to claim 1, wherein the inclined surfaces constituting the triangular wave prism include a first inclined surface having an inclination angle from the forming surface of 10° or more, and a second inclined surface having an inclination angle from the forming surface of 60° or more larger than that of the first inclined surface.

3. 3. The image display device according to claim 1, wherein the optical body is arranged so that all of the triangular wave-shaped prisms in the microprism structure extend in the lateral direction of the image display device and the first inclined surface is positioned downward.

4. 4. The image display device according to claim 1, wherein the arrangement pitch of the triangular wave prisms in the microprism structure is 5 to 50 μm.

5. 5. The image display device according to claim 1, wherein the triangular wave prisms in the microprism structure all extend continuously.

6. A method for manufacturing an optical body provided in the image display device according to any one of claims 1 to 5, comprising the steps of: A step of preparing a mold having a triangular wave-shaped groove formed therein; applying a release coating to the surface of the mold groove; applying a curable resin onto the release coating applied to the mold; a step of disposing a base film on the curable resin and then curing the curable resin; and peeling the laminate of the base film and the cured resin from the mold. A method for manufacturing an optical body, characterized in that the triangular wave groove of the mold comprises a first groove inclined surface having an inclination angle of 10° or more from the horizontal plane, and a second groove inclined surface having an inclination angle of 60° or more larger from the horizontal plane than the first inclined surface.

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