JP2021099408A - Image display device and method for manufacturing optical body - Google Patents

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

The present invention relates to a method for manufacturing an image display device and an optical body, which has high durability and can suppress a decrease in contrast due to external light irradiation.

Image display devices such as liquid crystal displays and organic light emitting diode displays, and devices equipped with image display functions such as smartphones and game machines may be exposed to strong light from the outside, resulting in a decrease in contrast due to light reflection and deterioration of contrast. It is desired to suppress deterioration of image quality (occurrence of color unevenness, ghost, etc.).
As a technique for suppressing a decrease in contrast due to external light irradiation, for example, a technique for providing an antiglare film or an antireflection film on an image display surface of an apparatus is known.

For example, Patent Document 1 discloses a technique for suppressing the generation of reflected light by providing an antireflection film having a fine concavo-convex structure (moss eye structure) having an average pitch equal to or less than the visible light wavelength band.

Japanese Unexamined Patent Publication No. 2003-98304

However, in the conventional technique of providing an antiglare film or an antireflection film on the image display surface, sufficient image contrast cannot be obtained when the image display device is placed in an environment exposed to strong external light. ..
Further, even when an antireflection film having 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, and further, fine irregularities are not obtained. Since the structure is delicate, it was necessary to improve the durability against external pressure.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing an image display device and an optical body, which has high durability and can suppress a decrease in contrast due to external light irradiation.

As a result of intensive research to solve the above problems, the present inventors provide an optical body having a microprism structure formed on the surface, and optimize the shape and arrangement direction of the microprism structure. As a result, the reflected light caused by the external light irradiation can be reliably deflected upward or downward when viewed from the observer, so that good image contrast can be obtained, and the microrhythm structure is described above. It was found that the durability of the optical body can be improved because the strength is higher than that of the fine moth-eye structure.

The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) An image display device including an optical body having a microprism structure formed on one surface thereof.
The microprism structure of the optical body is formed on the image display surface side of the image display device.
In the microprism structure, a plurality of triangular wave-shaped prisms having vertices protruding from the forming surface toward the image display surface are formed, and the triangular wave-shaped prisms are two slopes extending from the forming surface. An image display device characterized by being an asymmetric triangular wave prism having different inclination angles.
With the above configuration, the durability of the optical body can be enhanced and the decrease in contrast due to external light irradiation can be suppressed.
(2) The slopes constituting the triangular wavy prism include a first slope having an inclination angle of 10 ° or more from the forming surface and an inclination angle of 60 ° from the first forming surface. The image display device according to (1) above, which comprises a second slope having a larger slope.
(3) The optical body is arranged so that the triangular wavy prisms in the microprism structure extend in the lateral direction of the image display device and the first slope is located below. The image display device according to (1) or (2) above, wherein the image display device is characterized by the above.
(4) The image display device according to any one of (1) to (3) above, wherein the arrangement pitch of the triangular wavy prisms in the microprism structure is 5 to 50 μm.
(5) The image display device according to any one of (1) to (4) above, wherein all of the triangular wave-shaped prisms in the microprism structure are continuously extended.
(6) A method for manufacturing an optical body provided in the image display device according to any one of (1) to (5) above.
The process of preparing a mold with a triangular wavy groove and
The process of applying a release coating to the surface of the groove of the mold and
A step of applying a curable resin on the release coating applied to the mold, and
A step of arranging the base film on the curable resin and then curing the curable resin,
A step of peeling the laminate of the base film and the curable resin from the mold is provided.
The triangular wavy groove of the mold has a first groove slope having an inclination angle of 10 ° or more from the horizontal plane and a second groove slope having an inclination angle from the horizontal plane of 60 ° or more larger than the first slope. A method for manufacturing an optical body, which comprises.
With the above configuration, it is possible to obtain an image display device having high durability and capable of suppressing a decrease in contrast due to external light irradiation.

According to the present invention, it is possible to provide a method for manufacturing an image display device and an optical body, which has high durability and can suppress a decrease in contrast due to external light irradiation.

FIG. 5 is a perspective view schematically showing an embodiment of an optical body in an image display device of the present invention. (A) is an enlarged sectional view schematically showing an embodiment of the optical body in the image display device of the present invention, and (b) is the optical body in the image display device of the present invention. , Is an enlarged front view schematically showing an embodiment. It is sectional drawing which shows typically the flow of the light radiated from the image display element when the optical body in an image display apparatus has a symmetric triangular wave type prism structure. It is a flow chart which shows an example of the manufacturing process for manufacturing the optical body provided in the image display device which concerns on one Embodiment of this invention. It is a schematic perspective view for demonstrating the apparatus structure used for measuring the specular reflectance of the optical body samples of Examples 1 to 3 and Comparative Examples 2 to 5 in an Example. 3 is a graph showing the reflectance (%) according to the wavelength of the optical body samples of Examples 1 to 3 and Comparative Examples 2 to 5.

Hereinafter, an example of the embodiment of the present invention will be specifically described with reference to the drawings as necessary.
FIG. 1 is a perspective view showing an embodiment of an optical body in an image display device of the present invention, and FIG. 2A is an enlarged view of an embodiment of an optical body in an image display device of the present invention. It is a diagram schematically showing a cross section, and FIG. 3B is an enlarged view of an embodiment of an optical body in the image display device of the present invention, showing a state viewed from the front.
For convenience of explanation, some of the members disclosed in each drawing are schematically represented by a scale and shape different from the actual ones.

<Image display device>
First, an embodiment of the 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.
Then, in the image display device of the present invention, as shown in FIGS. 1 and 2A, 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 formed with a plurality of triangular wave-shaped prisms 12 having vertices 12C protruding from the forming surface 13 toward the image display surface side O, and the triangular wave-shaped prism 12 is formed on the forming surface 13. It is characterized in that the angles α and β of the two slopes 12A and 12B extending from are different asymmetric triangular wave prisms.

Regarding 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 observer side for viewing the image), and the triangular wavy prism 12 (hereinafter, hereinafter, the prism 12) constituting the microprism structure 11 is formed. By making the above-mentioned asymmetric triangular wave prism (sometimes simply referred to as a “prism”), as shown in FIG. 1, most of the reflected light generated from the irradiated external light is directly opposed to the observer. As a result of being able to deviate in a direction that does not occur (downward in FIG. 1), it is possible to effectively suppress a decrease in the contrast of the image from the image display element.
Further, as shown in FIG. 2B, the microprism structure 11 of the optical body 10 has a shape in which a triangular wavy prism 12 extends in the lateral direction T, and has fine irregularities like a moth-eye structure. Compared to the structure, it is stronger and can achieve high durability even outdoors or in situations where external pressure is applied.

Here, the microprism structure 11 formed on the forming surface 13 of the optical body 10 is composed of a plurality of prisms 12 having vertices 12C protruding from the forming surface 13 toward the image display surface side O.
By forming the microprism structure 11 on the image display surface side O (observer side viewing the image), as shown in FIG. 1, most of the reflected light generated from the irradiated external light is defined as the observer. It can be deflected in a direction that does not face it (downward in FIG. 1).
On the other hand, when the microprism structure 11 is formed on the image display element side I, the image display surface side O (observer side for viewing the image) is flat, so that most of the external light is reflected to the observer side. However, the contrast of the image is lowered and the image quality is deteriorated.

As shown in FIG. 2A, the microprism structure 11 is formed with a plurality of triangular wave-shaped prisms 12, and the triangular wave-shaped prisms 12 have two slopes (third) extending from the forming surface 13. This is an asymmetric triangular wave prism having different inclination angles α and β on the first slope 12A and the second slope 12B).
Due to the difference in the angles of the first slope 12A and the second slope 12B constituting the triangular wavy prism 12, most of the reflected light of the irradiated external light is not facing the observer (FIG. 1). The light from the image display element can be diverted downward) and can pass through the microprism structure 11 so that most of the light reaches the observer.

On the other hand, as shown in FIG. 3, when the inclination angles α and β of the first slope 120A and the second slope 120B extending from the forming surface 13 are the same (symmetrical triangular wave prism), the irradiated external light is emitted. The reflected light can be deflected in a direction (upward or downward) that does not face the observer. However, when the light from the image display element is transmitted, it is totally reflected in the target triangular wave prism, and the desired transparency cannot be obtained, as compared with the microprism structure 11 of the present invention made of the asymmetric triangular prism 12. Therefore, the contrast of the image is inferior.

As described above, from the viewpoint of obtaining better image contrast while suppressing deterioration of image quality, the slope forming the triangular wavy prism 12 has an inclination angle α of 10 ° from the forming surface 13. It is preferable that the first slope 12A and the second slope 12B having an inclination angle β from the forming surface 13 larger than the inclination angle α of the first slope 12A by 60 ° or more are preferable. It is more preferable that the difference between the inclination angle β of the second slope 12B and the inclination angle α of the first slope 12A is 70 ° or more.

Further, from the viewpoint that better image contrast can be obtained while suppressing deterioration of image quality, the inclination angle α of the first slope 12A of the triangular wavy prism 12 is preferably 10 ° or more. It is preferably 15 ° or more, and more preferably 20 ° or more.
Further, the inclination angle β of the second slope 12B of the triangular wavy prism 12 is preferably 70 ° or more, preferably 80 ° or more, and more preferably 85 ° or more.
As such a prism 12, for example, the inclination angle α of the triangular wave-shaped prism 12 may be 20 ° and the inclination angle β may be 90 °, or the inclination angle α of the triangular wave-shaped prism 12 may be 30 °. The inclination angle β can be 100 °, the inclination angle α of the triangular wavy prism 12 can be 35 °, and the inclination angle β can be 105 °.

The inclination angles α and β of the first slope 12A and the second slope 12B of the prism 12 may be the same inclination angle for each prism 12, and the inclination angles α and β for each prism 12. You can also change β. However, from the viewpoint of ease of production, prevention of unnecessary reflection, and better image contrast, it is preferable that all prisms 12 in the microprism structure 11 have the same inclination angles α and β.

Further, the extending direction of each prism 12 in the micro prism structure 11 is not particularly limited, but as shown in FIGS. 2 (a) and 2 (b), the triangular wavy prism 12 is an image. It is preferable that the optical body 10 is arranged so as to extend in the lateral direction T of the display device and so that the first slope 12A is located below.
By providing the optical body 10 so that the first slope 12A of the triangular wavy prism 12 is located below when viewed from the observer, the incident external light is reflected downward as shown in FIG. Therefore, it becomes difficult for the reflected light to enter the field of view of the observer, and a better image contrast can be obtained.

Further, as shown in FIGS. 2A and 2B, it is preferable that the triangular wave-shaped prisms 12 in the microprism structure 11 are continuously extended. Since there are no breaks in the triangular wavy prism 12, problems such as lines appearing in the image can be more reliably prevented, and further, since the bulk of the triangular wavy prism 12 becomes large, the durability of the glossy body 10 is increased. Can also be improved.

The number of triangular wavy prisms 12 formed in the microprism structure 11 is not particularly limited, and can be appropriately adjusted according to the required size of the optical body.

Further, as shown in FIGS. 2A and 2B, the arrangement pitch A of the triangular wavy prism 12 in the microprism structure 11 is preferably 5 to 50 μm, preferably 10 to 40 μm. Is more preferable. By setting the arrangement pitch A of the triangular wavy prism 12 to 5 μm or more, more excellent manufacturability (easiness of manufacturing the prism 12) can be obtained, and the arrangement pitch of the triangular wavy prism 12 can be obtained. By setting A to 50 μm or less, interference of reflected light can be prevented, and better image contrast can be obtained.

As shown in FIG. 2A, the microprism structure 11 is a support portion of the microprism structure 11 in which the triangular wavy prism 12 of the microprism structure 11 is not formed (hereinafter, the microprism structure 11). A “base portion 14”) may also be provided. By providing the base portion 14 in the micro prism structure 11, the ease of manufacturing can be ensured, the strength of the triangular wavy prism 12 can be increased, and the durability of the optical body 10 can also be improved.

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. This is because higher durability can be ensured when the thickness of the base portion 14 of the microprism structure is 1 μm or more.

Here, the material constituting the microprism structure 11 is not particularly limited. For example, from the viewpoint of moldability of the microprism structure 11, a curing reaction of an active energy ray-curable resin composition (photocurable resin composition, electron beam-curable resin composition), a thermosetting resin composition, or the like. A resin composition that is cured by the above method and contains, for example, a polymerizable compound and a polymerization initiator can be used.

Examples of the polymerizable compound include (i) an esterified product obtained by reacting 1 mol of polyhydric alcohol with 2 mol or more of (meth) acrylic acid or a derivative thereof, and (ii) polyhydric alcohol. And an esterified product obtained from a polyvalent carboxylic acid or an anhydride thereof and (meth) acrylic acid or a derivative thereof, and the like can be used.
Examples of (i) include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, and trimethyl propantri (meth). Acrylate, trimethylol ethanetri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, tetrahydrofurfuryl acrylate, glycerintri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipenta Examples thereof include erythritol hexa (meth) acrylate, tripenta erythritol hexa (meth) acrylate, tripenta erythritol hepta (meth) acrylate, acryloy monophorin, urethane acrylate, and the like.
Examples of (ii) include polyvalent alcohols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol, and malonic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, fumaric acid, itaconic acid, and maleic anhydride. Examples thereof include an esterified product obtained by reacting a polyvalent carboxylic acid or an anhydride thereof selected from the above with (meth) acrylic acid or a derivative thereof.
These polymerizable compounds may be used alone or in combination of two or more.

Further, when the resin composition is photocurable, examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl, benzophenone and p-methoxybenzophenone. , 2,2-Diethoxyacetophenone, α, α-dimethoxy-α-phenylacetophenone, methylphenylglycolate, ethylphenylglycolate, 4,4'-bis (dimethylamino) benzophenone, 1-hydroxy-cyclohexyl- Carbonyl compounds such as phenyl-ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthium monosulfide and tetramethylthiuram disulfide; 2,4,6-trimethylbenzoyluji Phenyl-phosphine oxide, benzoyldiethoxyphosphine oxide; and the like can be mentioned, and one or more of these can be used.

In the case of electron beam curability, examples of the electron beam polymerization initiator include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 4-phenylbenzophenone, and the like. Thioxanthons such as t-butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one , Benzyldimethylketal, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -Acetophenone such as butanone; benzoin ether such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2, Acylphosphine oxides such as 4,4-trimethylpentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; methylbenzoylformates, 1,7-bisacrydinylheptane, 9-phenylaclydin and the like. , And one or more of these can be used.

In the case of thermocurability, examples of the thermal polymerization initiator include methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctate, and t. -Organic peroxides such as butylperoxybenzoate and lauroyl peroxide; azo compounds such as azobisisobutyronitrile; N, N-dimethylaniline and N, N-dimethyl-p-toluidine in the organic peroxides. Examples thereof include a redox polymerization initiator in which an amine such as the above is combined.

These photopolymerization initiators, electron beam polymerization initiators, and thermal polymerization initiators may be used alone or in a desired combination.
The amount of the polymerization initiator is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable compound. Within such a range, the curing proceeds sufficiently, the molecular weight of the cured product becomes appropriate, and sufficient strength is obtained, and the cured product is colored due to the residue of the polymerization initiator and the like. The problem does not occur.

Further, the resin composition may contain a non-reactive polymer or an active energy ray sol-gel reactive component, if necessary, and may contain a thickener, a leveling agent, an ultraviolet absorber, a light stabilizer, and a heat stabilizer. It can also contain various additives such as agents, solvents and inorganic fillers.

The optical body 10 can further form a base material 15 adhered to the microprism structure 11.

The base material 15 may have a certain level of strength and may be transparent, and other configurations are not particularly limited and may be composed of conventionally used materials.
For example, examples of the material of the base material 15 include glass, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC) and the like.
In the present specification, "transparent" means that the transmittance of light having a wavelength belonging to the visible light band (approximately 360 nm to 830 nm) is high, and for example, the transmittance of the light is 70% or more. Means.
In one embodiment of the present invention, a study was conducted assuming a base material having a thickness of 125 μm as a PET base material.

Further, the shape of the base material 15 is not particularly limited except that it has a plate shape (film shape), and the thickness of the base material 15 is also not particularly limited, and is required for the optical body 10. It can be appropriately selected according to the conditions.

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 the image display device.
Further, the "image" displayed by the image display device of the present invention includes both still images and moving images.

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 drive circuit, or the like is provided on the image display element side I of the optical body 10. Further, when the image display device of the present invention is an organic EL display device, an image display element having a power supply, an electrode, a light emitting element, or the like is provided on the image display element side I of the optical body 10.

Further, in the image display device of the present invention, a member such as a protective film or a cover may be further provided on the image display surface side O of the optical body 10.

Regarding the image display device of the present invention, for example, in addition to a liquid crystal display device and an organic EL display device, an in-vehicle display device such as a car navigation system or a speed meter, a display device used outdoors, a game machine, a smartphone, a clock, etc. Can be mentioned.

<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, but for example, as shown in FIG.
The step of preparing the mold 20 in which the triangular wavy groove 23 is formed (FIG. 4 (a)) and
A step of applying a release coating 21 to the surface of the groove 23 of the mold 20 (FIG. 4B).
A step of applying the curable resin 22 on the release coating 21 applied to the mold 20 (FIG. 4 (c)) and
A step of arranging the base film 15 on the curable resin 22 and then curing the curable resin 22 (FIG. 4 (d)).
A manufacturing method including a step (FIG. 4 (e)) of peeling the laminate 10'of the base film 15 and the microprism structure 11 made of a cured resin from the mold 20 can be used. ..

The triangular wavy groove 23 of the mold 20 has a first groove slope 26A having an inclination angle α'from the horizontal plane of 10 ° or more and an inclination angle β'from the horizontal plane from the first slope 26A. It is also characterized in that it is composed of a second groove slope larger than 60 ° and 26B.
As a result, a plurality of triangular wave-shaped prisms 12 having vertices 12C protruding from the forming surface 13 to the image display surface side O are formed, and the triangular wave-shaped prisms 12 are formed from the forming surface 13. It is possible to reliably obtain a microprism structure 11 having asymmetric triangular wave prisms having different angles α and β of the two extending slopes 12A and 12B.

Regarding the step of preparing the mold 20, as shown in FIG. 4A, the groove 23 can be formed by cutting the mold material with a cutting tool 24 or the like, and the mold 20 can be created. However, it is not always necessary to create a mold, and if a mold 20 already exists, it may be used. Further, the cutting of the mold material can be made by processing by a method other than the cutting tool 24.

Further, the triangular wavy groove 23 of the mold 20 has a first groove slope 26A having an inclination angle α'from the horizontal plane of 10 ° or more and an inclination angle β'from the horizontal plane from the first slope 26A. It is also composed of a second groove slope and 26B, which are larger than 60 °, and the angle of inclination of the groove is appropriately changed according to the requirements of the angles α and β of the slopes 12A and 12B of the triangular wavy prism 12 described above. Can be done.

As shown in FIG. 4B, 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. This step has an advantage that the laminate 10'described later can be easily peeled off from the mold 20.
The type of the release coating 21 is not particularly limited, and a conventionally used release coating can be appropriately used. For example, fluorine coating treatment and the like can be mentioned.

As shown in FIG. 4C, the step of applying the curable resin 22 is a step of applying the curable resin 22 which is a material of the microprism structure 11 to the groove 23 of the mold 20. ..
The type of the curable resin is the same as that described in the description of the material of the microprism structure 11 described above.

Regarding the step of curing the curable resin 22, as shown in FIG. 4D, the base film 15 is placed on the curable resin 22, and then the curable resin 22 is cured. , A laminate of the base film 15 and the cured product of the curable resin 22 (later the microprism structure 11) can be formed.
When arranging the base film 15 on the curable resin 22, as shown in FIG. 4D, the curable resin 22 was pressed until all the grooves 23 were filled. After that, it is cured. The curing conditions can be appropriately set according to the type of resin such as ultraviolet rays, heat, and humidity.

In the step of peeling the laminated body 10'from the mold 20, as shown in FIG. 4 (e), the laminated body 10'of the base film 15 and the microprism structure 11 made of a cured resin is peeled off. It is a process. The peeled laminated body 10'becomes the above-mentioned optical body 10 as it is or after being processed.

Next, the present invention will be specifically described based on examples. However, the present invention is not limited to the following examples.

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

(Comparative Example 2)
A sample in which an AG film (manufactured by Keiwa Co., Ltd.) having an uneven surface was provided on a glass having a thickness of 1 mm was used as a sample of Comparative Example 2.

(Comparative Example 3)
A multilayer AR film (SiO ₂ / Nb ₂ O ₅ / SiO ₂ / Nb ₂ O ₅ / PET film, thickness 100 μm) was attached on a glass substrate with an adhesive film (“PDS1” manufactured by Panac Co., Ltd.). This was used as a sample of Comparative Example 3.

(Comparative Example 4)
A film (average pitch of unevenness 200 nm, average height of convexity 200 nm) in which a fine uneven structure (moss eye structure) made of UV curable acrylic resin is formed on a glass substrate is applied to an adhesive layer (Panac Co., Ltd. "PDS1". ) Was used as a sample of Comparative Example 4.

(Comparative Example 5)
As shown in FIG. 3, a symmetrical triangular wave type having a triangular wave-shaped prism 120 made of a UV-curable acrylic resin, the slopes constituting the prism 120 are all 45 °, and the average arrangement pitch is about 20 μm. The microprism structure 110 formed on the glass substrate was used as a sample of Comparative Example 5.

(Example 1)
As shown in FIG. 2A, it has a triangular wave-shaped prism 12 made of a UV-curable acrylic resin, the inclination angle α of the first slope 12A of the prism 12 is 20 °, and the inclination of the second slope 12B is 20 °. An asymmetric triangular wave type microprism structure 11 having an angle β of 90 ° and an average arrangement pitch of 100 μm formed on a glass substrate was used as a sample of Example 1.

(Example 2)
As shown in FIG. 2A, it has a triangular wavy prism 12 made of a UV curable acrylic resin, the inclination angle α of the first slope 12A of the prism 12 is 25 °, and the inclination of the second slope 12B is 25 °. A microprism structure 11 having an angle β of 90 ° and an average arrangement pitch of 50 μm formed on a glass substrate was used as a sample of Example 2.

(Example 3)
As shown in FIG. 2A, it has a triangular wavy prism 12 made of a UV curable acrylic resin, the inclination angle α of the first slope 12A of the prism 12 is 30 °, and the inclination of the second slope 12B is A microprism structure 11 having an angle β of 80 ° and an average arrangement pitch of 50 μm formed on a glass substrate was used as a sample of Example 3.

<Evaluation>
The following evaluations were performed on each sample of the laminate obtained in each Example and each Comparative Example. The evaluation results are shown in Table 1.

(1) Contrast evaluation The optical body of each sample was installed in front of the LED backlight diffused 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 installed so that the fine concavo-convex structure or the 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 the triangular wavy prisms in the fine concavo-convex structure all extend in the lateral direction and the first slope is located below.
First, with the LED backlight diffused light source turned off, the external light from the white LED is irradiated in the state of the maximum amount of light, and the characteristics of the reflected light (luminance of external light reflection, color of external light reflection: x, external light). The reflection color: y) was measured using a luminance meter (manufactured by Topcon Co., Ltd.).
Then, with the LED backlight diffused light source turned on and the panel color set to white, a luminance meter (manufactured by Topcon) was used to measure the brightness of the light from the panel.
Then, the contrast ratio (luminance of light from the LED backlight diffused light source / brightness of external light reflection) was calculated from the obtained brightness of the external light reflection and the brightness of the light from the LED backlight diffused light source.
Table 1 shows the measurement results and calculation results of the optical characteristics of each sample.

From the results in Table 1, it was found that when the samples of the optical bodies of Examples 1 to 3 were used, the contrast was significantly improved as compared with the case where the samples of each Comparative Example were used.
When the sample of Comparative Example 1 is used, it can be seen that the reflection of external light is large and the contrast ratio is low. Further, when the sample of Comparative Example 2 is used, it can be seen that the reflection of external light cannot be sufficiently suppressed although it is better than that of Comparative Example 1 due to the effect of the AG structure. Further, when the samples of Comparative Examples 3 and 4 are used, the effect of the antireflection treatment is somewhat observed, but when the sample is irradiated with strong external light, the brightness of the external light reflection is high and high. It can be seen that the contrast is not obtained.
When the sample of Comparative Example 5 is used, since the apex angle of the triangular wavy prism is 90 °, the reflection of external light can be deflected as in the samples of Examples 1 to 3, but the OLED is used. It is considered that the brightness is deteriorated because the light from the panel is totally reflected in the prism. In addition, it can be seen that the reflection of external light is also the most reflected, and sufficient contrast is not obtained.
In addition, from the results in Table 1, it was found that when the samples of the optical bodies of Examples 1 to 3 were used, the reflected chromaticity was also maintained in neutral, and the image display performance was also maintained in good condition. It was.

(2) Specular reflection measurement The optical bodies of the samples of Examples 1 to 3 and Comparative Examples 2 to 5 are irradiated with the light of a high-intensity LED lamp under the conditions shown in FIG. The specular reflectance (%) was measured according to (nm).
For the samples of Comparative Examples 4 and 5 and Examples 1 to 3, the optical body was installed so that the fine concavo-convex structure or the prism structure faces the display surface side (luminance measurement camera side). In addition, for the samples of Examples 1 to 3, as shown in FIG. 5, all the triangular wavy prisms in the fine concavo-convex structure extend in the lateral direction and the first slope is located below. The optical body was set. The measurement results are shown in FIG.

From the results of FIG. 6, it can be seen that when the samples of the optical bodies of Examples 1 to 3 are used, the reflected light due to the external light can be deflected, so that the specular reflection can be reduced to almost 0.
On the other hand, when the sample of the optical body of each comparative example is used, it can be seen that the specular reflectance is higher than that of Examples 1 to 3.
Further, although not shown, when fingerprints were attached to the optical bodies of the samples of Examples 1 to 3 and Comparative Examples 2 to 5, the optical bodies of the samples of Comparative Example 2 had a scattering effect due to the AG structure. In addition, the optical bodies of the samples of Comparative Examples 3 and 4 had different light interference conditions, resulting in higher 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 attached.

According to the present invention, it is possible to provide a method for manufacturing an image display device and an optical body, which has high durability and can suppress a decrease in contrast due to external light irradiation.

10 Optical body 10'Laminated body 11 Micro prism structure 12 Triangular wave prism 12A 1st slope, 12B 2nd slope 13 Forming surface 14 Base part 15 Base material, base material film 20 Mold 21 Anti-reflection structure 22 Curing Resin 23 Mold groove 23A 1st groove slope, 23B 1st groove slope 24 bytes 100 Optical body 110 Micro prism structure 120 Triangular wave prism α 1st slope slope angle, β 2nd slope slope Angle α'Inclination angle of the first groove slope, β'Inclination angle of the second groove slope

Claims (6)

An image display device including an optical body having a microprism structure formed on one surface.
The microprism structure of the optical body is formed on the image display surface side of the image display device.
In the microprism structure, a plurality of triangular wave-shaped prisms having vertices protruding from the forming surface toward the image display surface are formed, and the triangular wave-shaped prisms are two slopes extending from the forming surface. An image display device characterized by being an asymmetric triangular wave prism having different inclination angles. The slopes constituting the triangular wavy prism include a first slope having an inclination angle of 10 ° or more from the forming surface and a first slope having an inclination angle from the forming surface of 60 ° or more larger than the first slope. The image display device according to claim 1, wherein the image display device comprises two slopes. The optical body is arranged so that the triangular wavy prisms in the microprism structure extend in the lateral direction of the image display device and the first slope is located below. The image display device according to claim 1 or 2, wherein the image display device is characterized by the above. The image display device according to any one of claims 1 to 3, wherein the arrangement pitch of the triangular wavy prisms in the microprism structure is 5 to 50 μm. The image display device according to claim 1, wherein all of the triangular wave-shaped prisms in the microprism structure are continuously extended. A method for manufacturing an optical body provided in the image display device according to any one of claims 1 to 5.
The process of preparing a mold with a triangular wavy groove and
The process of applying a release coating to the surface of the groove of the mold and
A step of applying a curable resin on the release coating applied to the mold, and
A step of arranging the base film on the curable resin and then curing the curable resin,
A step of peeling the laminate of the base film and the cured resin from the mold is provided.
The triangular wavy groove of the mold has a first groove slope having an inclination angle of 10 ° or more from the horizontal plane and a second groove slope having an inclination angle from the horizontal plane of 60 ° or more larger than the first slope. A method for manufacturing an optical body, which comprises.

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