JP2013205696A - Optical sheet and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet with high productivity, capable of controlling a track of transmitted light, and a display device equipped with the optical sheet.SOLUTION: An optical sheet having a plurality of layers is arranged closer to an observer than a light source, controls light emitted from the light source and then emits the light toward the observer. The optical sheet includes: an optical functional layer which has light transmission parts aligned in parallel along a sheet surface and each being light transmissive, and light absorption parts formed between the light transmission parts and each being light absorbable; and an attenuation layer capable of attenuating transmitting light. A ratio (d/w) of a depth (d) in a layer thickness direction of the light absorption parts and a width (w) between the aligned light absorption parts is 3 or smaller. A display device is equipped with the optical sheet.

Description

  The present invention relates to an optical sheet that is disposed closer to an observer than a light source and can appropriately control light from the light source, and a display device including the optical sheet.

  In a display device such as a plasma television, a liquid crystal display device, and a projection television, an optical sheet is disposed closer to the viewer than the light source. This optical sheet has a role of providing a high-quality image to an observer.

  As a technique relating to the optical sheet, for example, in Patent Documents 1 and 2, layers in which light transmitting portions (light transmitting portions) and light absorbing portions (light absorbing portions) are alternately arranged along the sheet surface are disclosed. A viewing angle control sheet (optical sheet) provided with (optical functional layer) is disclosed.

JP 2006-184609 A JP 2006-171700 A

  According to the optical sheet provided with the optical functional layer as disclosed in Patent Documents 1 and 2, the light transmitting portion and the light absorbing portion of the optical functional layer are arranged by being arranged closer to the viewer than the light source of the display device. It is possible to control to reduce the viewing angle of the display device and increase the front luminance by changing the path of light from the light source at the interface. Further, by narrowing the viewing angle of the display device, effects such as peep prevention can be achieved.

  In order to control the viewing angle of the display device using the optical sheet having the optical function layer as described above, the light transmitted through the optical function layer in a direction inclined with respect to the normal to the sheet surface is transmitted to the light transmitting portion and the light. It was preferable to make the total reflection as much as possible by reaching the interface with the absorber. Therefore, in the conventional optical sheet, it was preferable to form the optical function layer by forming the light absorption part long (deeply) in the layer thickness direction or by narrowing the parallel interval of the light absorption part.

  In addition, when forming an optical functional layer in which the light transmitting portion and the light absorbing portion are alternately formed along the sheet surface as described above, a mold having a recess (groove) corresponding to the shape of the light transmitting portion is used. A method of forming a light-absorbing part in a groove formed between the light-transmitting parts after molding the light-transmitting part is preferable from the viewpoint of productivity and the like.

  However, if the light absorbing part is formed deep in the layer thickness direction as described above or the parallel interval between the light absorbing parts is narrowed, it is difficult to produce a mold for molding the light transmitting part. In addition, there is a problem that when the light transmitting portion is molded using a mold, the releasability is deteriorated and the productivity of the optical sheet is deteriorated.

  Therefore, an object of the present invention is to provide an optical sheet that is highly productive and that can control the path of transmitted light, and a display device including the optical sheet.

  The present invention will be described below.

  The invention according to claim 1 is an optical sheet provided with a plurality of layers, arranged on the viewer side from the light source, and controlling the light emitted from the light source to be emitted to the viewer side. A first optical functional layer including a light transmitting portion that can transmit light and a light absorbing portion that is formed between the light transmitting portions and that can absorb light; The ratio (d / w) of the distance (w) between the light absorption parts arranged in parallel with the depth (d) in the layer thickness direction of the light absorption parts is 3 or less. The optical sheet.

  According to a second aspect of the present invention, in the optical sheet according to the first aspect, the light transmitting portions that are arranged in parallel along the sheet surface and are capable of transmitting light, and the light formed between the light transmitting portions. A second optical functional layer comprising a light absorbing portion capable of absorbing, and a parallel direction of the light transmitting portion of the first optical functional layer and a parallel direction of the light transmitting portion of the second optical functional layer. The crossing is seen from the normal direction of the sheet surface.

  The invention according to claim 3 is the optical sheet according to claim 2, wherein the parallel direction of the light transmission parts of the first optical functional layer and the parallel direction of the light transmission parts of the second optical functional layer are the sheet. It is characterized by being orthogonal when viewed from the surface normal direction.

  According to a fourth aspect of the present invention, in the optical sheet according to any one of the first to third aspects, the light reducing layer is provided on the side closer to the viewer side than the first optical functional layer.

  The invention according to claim 5 is a display device comprising: a light source; and an optical sheet that is disposed closer to the viewer than the light source and controls the light emitted from the light source to be emitted toward the viewer. The optical sheet is provided with a light transmitting portion that can transmit light and that is arranged along the sheet surface, and a light absorbing portion that is formed between the light transmitting portions and that can absorb light. A functional layer and a light-reducing layer capable of attenuating transmitted light, and the ratio (d /) of the depth (d) of the light absorption part in the layer thickness direction and the interval (w) between the parallel light absorption parts w) is a display device of 3 or less.

  ADVANTAGE OF THE INVENTION According to this invention, productivity is high and can provide the optical sheet which can control the path | route of the light to permeate | transmit, and a display apparatus provided with this optical sheet.

2 is a diagram showing a cross section of the optical sheet 10 and schematically showing the layer configuration. FIG. FIG. 3 is an enlarged view of a part of the first optical function layer 12. It is the figure which compared the example of the optical path in the cross section of each one part of the conventional optical functional layer 112 and the 1st optical functional layer 12, and the said part. 5 is a diagram illustrating a part of a process of forming a first optical functional layer 12. FIG. It is a figure explaining other part of the process of forming the 1st optical function layer. It is a figure explaining the process of bonding. It is the figure which showed the cross section of the optical sheet 20, and represented the layer structure typically. It is the schematic which looked at the optical sheet 20 from the sheet surface normal direction. It is a figure showing the section of optical sheet 30, and showing the layer composition typically. It is the figure which showed the cross section of the optical sheet 40, and represented the layer structure typically. FIG. 9 is a front view of the optical sheet 50 and corresponds to FIG. 8. 1 is an exploded perspective view schematically showing a plasma television 100. FIG.

  The above-described operation and gain of the present invention will be clarified from embodiments for carrying out the invention described below. Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  First, the configuration of the optical sheet 10 according to the first embodiment will be described. FIG. 1 is a diagram schematically showing a layer configuration of a part of a cross section in the thickness direction of the optical sheet 10. In FIG. 1, for ease of viewing, some of the repeated symbols are omitted (the same applies to the following drawings). The optical sheet 10 is a sheet-like member that is provided closer to the viewer than the light source when disposed in the display device and can appropriately control light from the light source. In FIG. 1, the left side of the paper is the light source side, and the right side of the paper is the viewer side.

  The optical sheet 10 is a laminated sheet having a first base material layer 11, a first optical functional layer 12, a light attenuation layer 17, a second base material layer 18, and an AG layer 19. Each layer will be described below.

  The 1st base material layer 11 is a layer used as the base material for forming the 1st optical function layer 12 demonstrated in detail later. The main component of the material which comprises the 1st base material layer 11 will not be specifically limited if it has translucency. The “main component” means a component that is contained in an amount of 50% by mass or more based on the entire material constituting the layer (the same applies hereinafter). Examples of the main component of the material constituting the first base layer 11 include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, terephthalic acid-isophthalic acid-ethylene glycol copolymer, and terephthalic acid-cyclohexanedi. Polyester resins such as methanol-ethylene glycol copolymer, polyamide resins such as nylon 6, polyolefin resins such as polypropylene and polymethylpentene, acrylic resins such as polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, etc. Styrene resin, cellulose resin such as triacetyl cellulose, imide resin, polycarbonate resin and the like. Among these, PET is preferable from the viewpoints of mass productivity, price, availability, etc. in addition to performance. In addition to the main component, other resins and various additives may be appropriately added to the resin constituting the first base material layer 11. Examples of general additives include phenol-based antioxidants, lactone-based stabilizers, and the like. Moreover, you may add well-known additives, such as a ultraviolet absorber, a filler, a plasticizer, an antistatic agent, in these resins suitably as needed.

  The thickness of the first base material layer 11 is not particularly limited, but when PET is a main component, it is preferably 50 μm or more and 200 μm or less, and more preferably 75 μm or more and 125 μm or less.

  The first optical functional layer 12 is a layer that can control the path of light from the light source side and has a function that can appropriately absorb stray light and external light. The first optical functional layer 12 has a shape having the cross section shown in FIG. 1 and extending to the back / near side of the drawing. That is, in the cross section shown in FIG. 1, the light transmitting portion 13 having a substantially trapezoidal shape, and the light absorbing portion in which the cross section formed between the light transmitting portions 13 is formed in the substantially trapezoidal concave portion 13 a (see FIG. 2). 14. In FIG. 2, the two light absorption parts 14 and the light transmission part 13 adjacent to this are expanded and shown among the optical function layers 12. FIG.

  The light transmitting portion 13 is a portion that transmits light. In the cross section shown in FIGS. 1 and 2, the light transmitting portion 13 has a lower base on the surface on the first base material layer 11 side, and the lower surface on the opposite side. An element with a substantially trapezoidal cross section having an upper base shorter than the bottom. And the light transmissive part 13 is parallelly arranged in the direction along the sheet surface at a predetermined interval. Accordingly, a recess 13a having a substantially trapezoidal cross section is formed therebetween. The concave portion 13a is a groove having a trapezoidal cross section having a lower base on the upper bottom side of the light transmitting portion 13 and an upper base on the lower bottom side of the light transmitting portion 13, and a necessary material described later herein. As a result, the light absorbing portion 14 is formed.

  The period (pitch) p in which the light transmission parts 13 are arranged in parallel can be made wider than the conventional one as will be described in detail later. The ratio (d / p) between the pitch p of the light transmitting portion 13 and the depth d of the light absorbing portion 14 in the layer thickness direction is preferably 2.5 or less, for example, and more preferably 1.5 or less. . Thus, by making the pitch p of the light transmission parts 13 wider than the conventional one, it becomes easy to produce a mold used for molding the light transmission part 13 and the light transmission part 13 is molded using the mold. Therefore, the productivity of the optical sheet 10 can be improved.

The light transmission portion 13 has a refractive index of N _p, having optical transparency. Such a light transmission part 13 can be formed by hardening the light transmission part structure composition mentioned later, for example. Details will be described later. The value of the refractive index N _p is not particularly limited, but is preferably from availability viewpoint, etc. apply material is 1.49 to 1.56.

  Next, the light absorption unit 14 will be described. The light absorption unit 14 is configured to be able to absorb light as a whole. Moreover, the light absorption part 14 is formed in the recessed part 13a between the above-mentioned light transmission parts 13, and has a shape which follows the recessed part 13a in general. Therefore, in the present embodiment, in the cross section (sheet thickness direction cross section) shown in FIGS. 1 and 2, the cross-sectional shape of the light absorbing portion 14 is a trapezoid whose width becomes narrower from the light source side toward the observer side. It is. The angle θ formed by the hypotenuse of the trapezoid and the normal to the sheet surface is preferably 3 ° or more and 15 ° or less, for example. In this way, by setting the hypotenuse to a predetermined angle, the light that has entered the first optical functional layer 12 at a large angle with respect to the normal to the sheet surface can be converted into a light transmitting portion 13 and a light absorbing portion as will be described later. 14 is totally reflected at the interface with the surface 14, and the angle with respect to the normal to the sheet surface is reduced to facilitate light emission. Therefore, the viewing angle of the display device provided with the optical sheet 10 is narrowed, and it is easy to achieve effects such as peeping prevention. In addition, the front luminance of the display device can be improved by emitting light incident on the first optical functional layer 12 at a large angle with respect to the sheet surface normal while reducing the angle with respect to the sheet surface normal. it can.

The light absorbing portion 14 is the same as the refractive index N _p of the light transmitting portion 13, or composed of a predetermined material having smaller refractive index N _b which. When the refractive index N _b of the refractive index N _p and the light absorbing portion 14 of the light transmitting portion 13 was set to N _p> N _b is the interface between the light absorbing portion 14 and the light transmission section 13, the refractive index difference and the interface Based on the relationship with the light incident angle, a part of the light can be appropriately reflected at this interface and emitted to the observer. Thereby, in addition to the light transmitted through the light transmission part 13 without being reflected at the interface, the light reflected at the interface is provided to the observer in this way, so that the front luminance of the display device including the optical sheet 10 is improved. It becomes easy to let you. In addition, the light incident on the first optical functional layer 12 at a large angle with respect to the sheet surface normal can be reflected at the interface and emitted at a small angle with respect to the sheet surface normal. Narrowing the viewing angle of a display device provided with an effect such as peeping prevention can be achieved. Furthermore, since part of outside light and stray light is incident on the light absorbing portion 14 without being reflected at the interface, the contrast of the display device including the optical sheet 10 is improved. The difference in refractive index between N _p and N _b is not particularly limited, but is preferably 0 or more and 0.06 or less. The larger the refractive index difference, the more light is reflected at the interface.

In the present embodiment, the light absorbing portion 14 has light absorbing performance by containing the light absorbing particles 16. Such a light absorption part 14 can be formed by filling the concave part 13a with a binder (light absorption part constituting composition) in which the light absorption particles 16 are dispersed. In this case, the refractive index of the binder is N _b. The material and method for forming the light absorbing portion 14 will be described in detail later.

  The means for absorbing light is not limited to the method using light absorbing particles as in this embodiment. In addition, for example, the entire light absorbing portion can be colored with a pigment or a dye.

  The depth d of the light absorbing portion 14 in the layer thickness direction can be made shallower than the conventional one as will be described in detail later. In the cross section shown in FIG. 2, the ratio (d / w) to the distance between the light absorbing portions 14 in parallel with the depth d of the light absorbing portion 14 (the width of the light transmitting portion 13 (the length of the upper base)) w is For example, it is preferably 3 or less, and more preferably 1.5 or less. Thus, by making the depth d of the light absorbing portion 14 (recessed portion 13a) shallower than the conventional one, it becomes easy to manufacture a mold used for molding the light transmitting portion 13, and light is transmitted using the mold. Since the releasability when molding the portion 13 can be improved, the productivity of the optical sheet 10 can be improved.

  Further, the thickness of the first optical functional layer 12 is not particularly limited, but can be made thinner than the conventional one by forming the light absorbing portion 14 shallow as described above. The thickness t of the optical function layer 12 is preferably set to, for example, the depth d + 50 μm or less of the light absorbing portion 14. By forming the first optical functional layer 12 thin, material costs can be saved, and the production cost of the optical sheet 10 can be reduced.

  Returning to FIG. 1, the light reduction layer 17 will be described. The light attenuation layer 17 is a layer having a function of attenuating transmitted light. In the present embodiment, the light attenuation layer 17 is provided on the side closer to the viewer side than the first optical functional layer 12. In the present embodiment, the light reducing layer 17 also has a function as an adhesive layer for bonding the first base material layer 11 and the second base material layer 18 together. Such a light reduction layer 17 can be comprised by the adhesive composition containing an adhesive and a toning pigment | dye, for example. For example, the pressure-sensitive adhesive composition can be formed into a film, or can be formed on a transparent substrate or other functional filter, and dried or cured as necessary.

  As the toning dye used for the light reducing layer 17, a known dye having a maximum absorption wavelength in the visible region of 380 nm to 780 nm can be used in any combination depending on the purpose. Known dyes that can be used as toning dyes include the dyes described in JP 2000-275432 A, JP 2001-188121 A, JP 2001-350013 A, JP 2002-131530 A, and the like. Can be suitably used. In addition, other dyes such as anthraquinone, naphthalene, azo, phthalocyanine, pyromethene, tetraazaporphyrin, squarylium, and cyanine that absorb visible light such as yellow light, red light, and blue light. Can be used.

  In addition, as the pressure-sensitive adhesive used for the light reducing layer 17, a publicly known one capable of obtaining necessary light transmittance, adhesiveness, and weather resistance can be used. Furthermore, the pressure-sensitive adhesive composition constituting the light reducing layer 17 can appropriately include known additives such as a UV absorber, a near infrared absorber, and a neon ray absorber.

The thickness of the light reduction layer 17 is preferably 20 μm or more and 50 μm or less, for example. By setting the thickness of the light-reducing layer 17 to 20 μm or more, it is possible to improve the followability to the layer in contact with the light-reducing layer 17 and to suppress the occurrence of defects involving bubbles. Moreover, it becomes easy to apply | coat the adhesive composition which comprises the light attenuation layer 17 to uniform thickness because the thickness of the light attenuation layer 17 shall be 50 micrometers or less.
Furthermore, it is desirable that the storage elastic modulus of the pressure-sensitive adhesive composition constituting the light reducing layer 17 is 0.1 MPa or more and 0.8 MPa or less. By setting the storage elastic modulus of the pressure-sensitive adhesive composition to 0.8 MPa or less, it is possible to improve followability to the layer in contact with the light-reducing layer 17 and to suppress the occurrence of defects involving air bubbles. Further, by setting the storage elastic modulus of the pressure-sensitive adhesive composition to 0.1 MPa or more, the pressure-sensitive adhesive composition does not become too soft, and it is possible to suppress the occurrence of defects such as dirt due to protrusion of the pressure-sensitive adhesive composition. It becomes easy to handle the composition. In the present embodiment, as described above, the first optical functional layer 12 can be formed thinner than the conventional optical functional layer. When the first optical functional layer 12 is formed thin, it is preferable to select an adhesive composition that can increase the rigidity of the optical sheet 10 for the light reducing layer 17.

  The transmittance of the light reducing layer 17 can be adjusted as appropriate by adjusting the type and blending amount of the toning pigment. The total light transmittance in the visible light region of the light reducing layer 17 is preferably 40% or more. If it is 40% or more, although depending on the form of other layers (especially the first optical functional layer 12), etc., it is appropriate to reduce the viewing angle of the display device including the optical sheet 10 as described later. It becomes easy to display the luminance.

  The light that passes through the light reducing layer 17 is easily attenuated as the light path in the light reducing layer 17 is longer, that is, the light path has a larger inclination with respect to the normal to the sheet surface. Accordingly, the light emitted through the light reducing layer 17 has a relatively small amount of light with a small inclination with respect to the sheet surface normal, and a relatively small amount of light with a large inclination with respect to the sheet surface normal. Therefore, according to the optical sheet 10 provided with the dimming layer 17, the viewing angle can be narrowed when provided in the display device. By narrowing the viewing angle in this way, effects such as peep prevention can be achieved.

  Conventionally, a viewing angle of a display device is narrowed by using an optical sheet having an optical functional layer in which light transmitting portions and light absorbing portions such as the first optical functional layer 12 are alternately arranged along the sheet surface. For this reason, it was preferable to make the light absorption part deeper in the layer thickness direction and to narrow the pitch of the light absorption part. By deepening the light absorption part in the layer thickness direction and / or narrowing the pitch of the light absorption part, the light having a large inclination of the path with respect to the normal to the sheet surface is reflected at the interface between the light transmission part and the light absorption part. This is because such light is reflected at the interface and the optical path is easily changed to a direction in which the inclination with respect to the normal to the sheet surface is small. FIG. 3 shows a cross-section of a part of each of the conventional optical functional layer 112 and the first optical functional layer 12 and a comparison of optical path examples in the part. In FIG. 3, arrows L1 to L6 indicate examples of optical paths, but these are conceptually shown and do not accurately indicate the reflection angle or the like. The light absorbing portion 114 of the conventional optical functional layer 112 is formed deeper in the layer thickness direction than the light absorbing portion 14 of the first optical functional layer 12, and the pitch is narrow. As shown in FIG. 3, the first optical functional layer 12 and the conventional optical functional layer 112 both have the light L1, L4, L5 that has reached the interface between the light transmitting portions 13, 113 and the light absorbing portions 14, 114. , L6 can be reflected toward a direction close to the front direction (the normal direction of the sheet surface). However, the conventional optical functional layer 112 in which the light absorption part is deep in the layer thickness direction and the pitch of the light absorption part is narrower reaches the interface between the light transmission part and the light absorption part than the first optical functional layer 12. There is a lot of reflected light.

  However, when the light absorption part is deepened in the layer thickness direction or the pitch of the light absorption part is narrowed, when the light transmission part is molded using a mold as described later, it is used for molding the light transmission part. In some cases, it becomes difficult to produce a mold, and when the light transmitting portion is molded using the mold, the releasability may be deteriorated.

  According to the optical sheet 10, even if it is light that has passed through the light transmission part 13 without reaching the interface between the light transmission part 13 and the light absorption part 14, light having a large path inclination with respect to the normal to the sheet surface (For example, L2 and L3 shown in FIG. 3) are likely to be attenuated in the light reducing layer 17 because they pass through the light reducing layer 17 through a long path. Therefore, according to the optical sheet 10, even if the light absorbing portion 13 is shallow in the layer thickness direction and / or the pitch of the light absorbing portion 13 is increased, the viewing angle of the display device including the optical sheet 10 is narrowed. Can do.

  Conventionally, an optical functional layer such as the first optical functional layer 12 is used as one of the purposes to reduce the viewing angle and increase the front luminance as described above when provided in a display device. The For this reason, it has been considered that it is not desirable to use an optical functional layer in combination with a layer that attenuates transmitted light, such as the light reducing layer 17. However, the present inventor can provide an optical sheet having high productivity and capable of controlling the path of transmitted light by using the first optical functional layer 12 and the light reducing layer 17 in combination as described above. I found it.

  Returning to FIG. 1, the second base material layer 18 will be described. The second base material layer 18 is a layer that becomes a base material for forming the AG layer 19. Since the 2nd base material layer 18 can be set as the structure similar to the 1st base material layer 11, detailed description is abbreviate | omitted.

  Next, the AG layer 19 will be described. AG means anti-glare, and the AG layer 19 is a layer having a function capable of preventing glare when an observer looks at the screen. The AG layer 19 can be constituted by, for example, a normally available antiglare film. In the present embodiment, this is the AG layer, but an AR layer or an HC layer may be arranged instead of the AG layer. The AR layer means an “anti-reflection layer” and is a layer that can prevent reflection. The HC layer means a “hard coat layer” and can protect the surface of the optical sheet.

  Next, a method for manufacturing the optical sheet 10 will be described. Hereinafter, an example of each process for manufacturing the optical sheet 10 will be described. The optical sheet 10 is a sheet coil 153 (see FIG. 6) in which a belt-like sheet 153 ′ (see FIG. 6) is wound in a coil shape, and the belt-like sheet 153 ′ is unwound from the sheet coil 153. It can be produced by cutting out from the belt-like sheet 153 ′ to a predetermined size. Further, the strip-shaped sheet 153 ′ is reduced separately from the step of forming the first laminated sheet 150 ′ (see FIG. 6) including the first optical functional layer 12 and the step of forming the first laminated sheet 150 ′. It can be manufactured through a step of forming a second laminated sheet 151 ′ (see FIG. 6) including the optical layer (adhesive layer) 17 and a step of bonding them together. Hereinafter, the manufacturing method example of the optical sheet 10 will be described in more detail.

  The step of forming the first laminated sheet 150 ′ is a step of manufacturing the first laminated sheet 150 ′ in which the first optical functional layer 12 is formed on the base material 11 ′ to be the first base material layer 11. Can do. 4 and 5 are diagrams for schematically explaining a part of the process.

  First, the light transmission portion 13 is molded on the base material 11 ′ including the layer that becomes the first base material layer 11 to obtain an intermediate sheet 10 ′ that is an intermediate sheet. In order to mold the light transmitting portion 13, a mold roll 120 having a groove having a shape corresponding to the light transmitting portion 13 and the light absorbing portion 14 (concave portion 13a) is prepared at a predetermined pitch. At this time, as described above, according to the optical sheet 10, the light absorbing portion 14 (concave portion 13a) can be shallowed or the pitch can be widened, so that the mold roll 120 can be easily manufactured.

  Next, as shown in FIG. 4, the base material 11 ′ is fed between the mold roll 120 and the nip roll 121. The arrow IV shown in FIG. 4 is the direction in which the substrate 11 'is fed. In accordance with the feeding of the base material 11 ′, the droplets of the light transmission part constituting composition 13 ′ are continuously supplied from the supply device between the mold roll 120 and the base material 11 ′. When supplying the light transmitting portion constituting composition 13 ′ onto the base material 11 ′ from the supply device, a bank 122 in which the light transmitting portion constituting composition 13 ′ is accumulated is formed between the mold roll 120 and the base material 11 ′. To be formed. In the bank 122, the light transmitting portion constituting composition 13 'spreads in the width direction of the base material 11' (back side / front side in FIG. 4).

  As the light transmission part constituting composition 13 ', for example, a photocurable resin composition in which a photocurable prepolymer (P1) and a reactive dilution monomer (M1) are blended is preferably used.

  Examples of the photocurable prepolymer (P1) include epoxy acrylate-based, urethane acrylate-based, polyether acrylate-based, polyester acrylate-based, and polythiol-based prepolymers.

  Examples of the reactive dilution monomer (M1) include vinyl pyrrolidone, 2-ethylhexyl acrylate, β-hydroxy acrylate, and tetrahydrofurfuryl acrylate.

  These photocurable prepolymers (P1) and reactive diluent monomers (M1) can be used alone or in combination of two or more.

  Further, if necessary, a mold release agent and a photopolymerization initiator may be added to the light transmitting part constituting composition, and as various additives for improving the coating film and improving the coating suitability. Silicone additives, rheology control agents, defoaming agents, antistatic agents, ultraviolet absorbers and the like can also be added.

  The light transmitting part constituting composition 13 ′ supplied between the mold roll 120 and the base material 11 ′ as described above is pressed by the pressing force between the mold roll 120 and the nip roll 121. It is filled between the mold rolls 120. Thereafter, the light transmissive part 13 can be formed by irradiating the light transmissive part constituting composition 13 ′ with the light irradiation device 123 and curing the light transmissive part constituting composition 13 ′. The intermediate sheet 10 ′ in which the light transmission part 13 is formed on the first base material layer 11 is pulled off from the mold roll 120 by being pulled through the peeling roll 124. At this time, as described above, according to the optical sheet 10, the light transmitting portion 14 can be shallowed or the pitch can be widened, so that the mold releasability of the mold roll 120 is improved.

  Next, as shown in FIG. 5, the light absorbing portion 14 is formed between the light transmitting portions 13 of the intermediate sheet 10 ′ to obtain the first optical functional layer 12. Specifically, the light absorbing portion constituting composition 125 is supplied onto the light transmitting portion 13, and the light absorbing portion constituting composition 125 is filled in the groove 13 a between the light transmitting portions 13 by the doctor blade 126. Thereafter, the surplus light absorbing portion constituting composition 125 is scraped off, and the light absorbing portion constituting composition 125 remaining in the groove 13a between the light transmitting portions 13 is irradiated with light and cured. Thereby, the light absorption part 14 can be formed. Note that the arrow V shown in FIG. 5 is the feeding direction of the intermediate sheet 10 '.

  The light absorbing portion constituting composition is obtained by dispersing light absorbing particles in a binder constituting composition. Although what is used as the said binder constituent composition is not specifically limited, For example, the photocurable resin composition which mix | blended the photocurable prepolymer (P2) and the reactive dilution monomer (M2) is used preferably.

  Examples of the photocurable prepolymer (P2) include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate.

  Moreover, as said reactive dilution monomer (M2), a vinyl monomer, a (meth) acrylic acid ester monomer, and a (meth) acrylamide derivative are mentioned as a monofunctional monomer, for example. Moreover, (meth) acrylate type thing is mentioned as a polyfunctional monomer.

  These photocurable prepolymers (P2) and reactive dilution monomers (M2) can be used alone or in combination of two or more.

  In addition, you may further add a photoinitiator, silicone, an antifoamer, a leveling agent, a solvent, etc. as an additive.

  As the light absorbing particles, light absorbing colored particles such as carbon black are preferably used. However, the light absorbing particles are not limited to these, and colored particles that selectively absorb a specific wavelength in accordance with the characteristics of the image light may be used as the light absorbing particles. Specific examples include organic fine particles colored with metal salts such as carbon black, graphite, and black iron oxide, dyes, pigments, colored glass beads, and the like. In particular, colored organic fine particles are preferably used from the viewpoints of cost, quality, availability, and the like. More specifically, acrylic cross-linked fine particles containing carbon black, urethane cross-linked fine particles containing carbon black, and the like are preferably used. Such colored particles are usually contained in the binder in the range of 3% by mass to 30% by mass. The average particle diameter of the colored particles is preferably 1.0 μm or more and 20 μm or less. Here, the “average particle diameter” means that obtained by particle size measurement by a mass distribution method.

  The means for absorbing light is not limited to the method using light absorbing particles as in this embodiment. Other examples include, for example, coloring the entire composition of the light absorbing portion constituting the light absorbing portion with a pigment or dye to form a light absorbing portion colored entirely.

  From the method described above, a first laminated sheet 150 ′ (see FIG. 6) having the first base material layer 11 and the first optical functional layer 12 laminated thereon can be obtained. The first laminated sheet 150 ′ thus formed is wound into a coil shape to form a first laminated sheet coil 150 (see FIG. 6).

  Next, a process of forming the second laminated sheet 151 ′ (see FIG. 6) including the light reducing layer 17 will be described. The second laminated sheet 151 ′ is a sheet manufactured separately from the first laminated sheet 150 ′ described above, and is a sheet including the light reducing layer 17, the second base material layer 18 and the AG layer 19 of the optical sheet 10. .

  In the step of forming the second laminated sheet 151 ′, the pressure-sensitive adhesive composition that becomes the light reducing layer 17 is applied on the second base material layer 18 having the AG layer 19 formed on one surface. Next, a release sheet is laminated on the side of the pressure-sensitive adhesive composition where the second base material layer 18 is not disposed. As a result, a second laminated sheet 151 ′ in which the light reducing layer 17 (adhesive) is sandwiched between the release sheet and the second base material layer 18 is obtained. Furthermore, this is wound up and aged to stabilize the adhesive, thereby obtaining a second laminated sheet coil 151 (see FIG. 6).

  In this way, the second laminated sheet 151 ′ is formed, and this is wound into a coil shape to obtain the second laminated sheet coil 151.

  Next, the process of bonding the first laminated sheet 150 'and the second laminated sheet 151' will be described. FIG. 6 schematically shows the bonding apparatus 30.

  The laminating apparatus 30 is provided with unwinders 131 and 132. The unwinding machine 131 is provided with the first laminated sheet coil 150 described above, and the unwinding machine 132 is provided with the second laminated sheet coil 151.

  The first laminated sheet 150 ′ and the second laminated sheet 151 ′ are unwound from the unwinding machines 131 and 132 and proceed in the direction of the straight arrow shown in FIG. 6. Then, the first laminated sheet 150 ′ and the second laminated sheet 151 ′ are bonded together by advancing them so as to be sandwiched between the pair of bonding rolls 133 and 134.

  However, since the release sheet is laminated on the light reducing layer 17 (adhesive), the second laminated sheet 151 ′ cannot be bonded to the first laminated sheet 150 ′ as it is. Therefore, the release sheet is peeled off by the release roll 135 before the second laminated sheet 151 ′ reaches the bonding rolls 133 and 134. As a result, the light reducing layer 17 is exposed, and the first laminated sheet 150 ′ and the light reducing layer 17 are appropriately bonded together. The peeled release sheet is taken up by a winder 136 to form a release sheet coil 152.

  Here, a tension adjusting roll 137 is provided between the unwinding machine 131 and the bonding rolls 133 and 134. Similarly, a tension adjusting roll 138 is also disposed between the unwinder 132 and the bonding rolls 133 and 134. By moving these tension adjusting rolls 137 and 138, the tension of the first laminated sheet 150 'and the second laminated sheet 151' in contact can be changed and adjusted.

  After the first laminated sheet 150 ′ and the second laminated sheet 151 ′ are bonded in this way, the belt-like sheet 153 ′ having the layer configuration shown in FIG. 1 is maintained at a predetermined tension. On the other hand, the sheet coil 153 is wound by the winder 138.

  FIG. 7 is a view schematically showing the layer structure of the optical sheet 20 according to the second embodiment. The optical sheet 20 includes a second optical functional layer 22 and a third base serving as a base material for the second optical functional layer 22 between the optical functional layer 12 and the light reducing layer 17 of the optical sheet 10 described above. The material layer 21 and the adhesive layer 25 that bonds the first base material layer 11 and the second optical functional layer 22 are laminated.

  The third base layer 21 has the same configuration as the first base layer 11 and the second optical functional layer 22 has the same configuration as the first optical functional layer 12, but the second optical functional layer 22 has the same configuration as the first optical functional layer 12. The light absorbing portion 24 of the optical functional layer 22 (only the light transmitting portion 23 appears in FIG. 7 but not the light absorbing portion 24) is orthogonal to the light absorbing portion 14 of the first optical functional layer 12. It is arranged in the direction. FIG. 8 shows the relationship between the light absorbing portion 14 of the first optical functional layer 12 and the light absorbing portion 24 of the second optical functional layer 22. FIG. 8 is a schematic view of the optical sheet 20 as seen from the front (sheet surface normal direction).

  The pressure-sensitive adhesive layer 25 is a layer composed of a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive. As the pressure-sensitive adhesive, known ones that can obtain necessary light transmittance, pressure-sensitive adhesiveness, and weather resistance can be used. The pressure-sensitive adhesive composition may contain a UV absorber, a near-infrared absorber, a neon ray absorber, a toning pigment, and the like.

  According to the optical sheet 20, as with the optical sheet 10, the first optical functional layer 12 has an effect of narrowing the viewing angle and improving the front luminance in a plane parallel to a predetermined direction (parallel direction of the light transmitting portion 13). In addition, the second optical functional layer 22 can narrow the viewing angle and improve the front luminance even in a plane parallel to the orthogonal direction (the parallel direction of the light transmission portions 23). Further, the light attenuation layer 17 is disposed closer to the viewer than the first optical functional layer 12 and the second optical functional layer 22, so that the light absorption of the first optical functional layer 12 is similar to the optical sheet 10. The pitch can be increased by making the portion 14 shallow, and the pitch of the second optical functional layer 22 can also be increased by making the light absorbing portion 14 shallow. Therefore, the optical sheet 20 can be an optical sheet excellent in productivity.

  FIG. 9 is a diagram schematically showing the layer structure of the optical sheet 30 according to the third embodiment. The optical sheet 30 includes a second optical functional layer 22 and a third base material serving as a base material for the second optical functional layer 22 between the light reducing layer 17 and the AG layer 19 of the optical sheet 10 described above. Layer 21 is laminated. The third base material layer 21 also serves as a base material for the AG layer 19.

  The optical sheet 30 is excellent in productivity like the optical sheet 10, and the first optical functional layer 12 narrows the viewing angle in a plane parallel to a predetermined direction (parallel direction of the light transmitting portion 13) and the front luminance. In addition to the effect of improving the viewing angle, the second optical functional layer 22 can narrow the viewing angle and improve the front luminance even in a plane parallel to the orthogonal direction (the parallel direction of the light transmission portions 23).

  FIG. 10 is a view schematically showing the layer structure of the optical sheet 40 according to the fourth embodiment. The optical sheet 40 replaces the light reducing layer 17 of the optical sheet 30 with the pressure-sensitive adhesive layer 25, and the base material layer 27 serving as the base material of the second optical functional layer 22 also functions as a light reducing layer. . The base material layer 27 can be formed, for example, by mixing a toning pigment that can be used for the above-described light reducing layer 17 with a material that can constitute the above-described first base material layer 11.

  The optical sheet 40 is excellent in productivity, like the optical sheet 20, and the first optical functional layer 12 narrows the viewing angle in a plane parallel to a predetermined direction (parallel direction of the light transmission portion 13) and the front surface. In addition to the effect of improving the luminance, the second optical functional layer 22 can narrow the viewing angle and improve the front luminance even in a plane parallel to the orthogonal direction (parallel direction of the light transmission portion 23). .

  In the description so far, as shown in FIG. 8, in the front view of the optical sheet, the light absorbing portion 14 of the first optical functional layer 12 and the light absorbing portion 24 of the second optical functional layer 22 are respectively The embodiment in which the optical sheet is arranged in parallel with any one of the four sides has been described as an example. However, the light absorption part of the first optical functional layer and the light absorption part of the second optical functional layer may be juxtaposed in directions inclined with respect to the four sides of the optical sheet in a front view of the optical sheet. . FIG. 11 is a front view of an optical sheet 50 according to another embodiment, and corresponds to FIG. As shown in FIG. 11, when viewed from the normal direction of the sheet surface, the parallel direction of the light absorbing portion 114 of the first optical functional layer and the parallel direction of the light absorbing portion 124 of the second optical functional layer are respectively The direction may be inclined with respect to the four sides of the optical sheet 50 and may intersect with each other. At this time, the crossing angle α between the light absorbing portion 114 and the light absorbing portion 124 is not particularly limited, but is preferably 45 ° or more and 90 ° or less, for example, 90 ° from the viewpoint of peep prevention. More preferred.

  In the above description, the front and back of the first optical functional layer 12 and the second optical functional layer 22 are in the same direction, that is, the side where the cross-sectional shape of the light absorbing portion is the light source side in both optical functional layers. In the above description, the trapezoidal shape whose width becomes narrower toward the viewer side has been described as an example, but the two may be arranged in different directions. However, if the front and back of the first optical functional layer 12 are reversed, the light from the light source side is diffused. Therefore, from the viewpoint of narrowing the viewing angle in a predetermined direction, at least one optical functional layer is disposed in the same direction as the first optical functional layer 12 on the light source side from the light reducing layer. Further, the optical functional layer disposed on the light source side with respect to the light reducing layer has the same orientation as that of the first optical functional layer 12, and the first optical functional layer 12 is opposite to the first optical functional layer 12, and the parallel direction of the light transmitting portions is different. Is arranged closer to the observer than the light reducing layer, the viewing angle is narrowed in the plane parallel to the parallel direction of the light transmitting portion of the optical functional layer on the light source side from the light reducing layer, and the observer side is closer to the light reducing layer. In the plane parallel to the parallel direction of the light transmission portions of the optical function layer, the viewing angle can be widened. Therefore, for example, it is possible to narrow the viewing angle in the vertical direction of the display device and widen the viewing angle in the horizontal direction.

  In the above description, the cross-sectional shapes of the light transmission part and the light absorption part have been described by illustrating a trapezoidal shape. However, the cross-sectional shape may be a triangle or a rectangle. These trapezoids, triangles, The rectangle may be a strict trapezoid, a triangle, a shape with rounded corners instead of a rectangle, or a shape in which each side is a polygonal line or a curve.

  Next, the display device will be described. The optical sheet described above can be applied to a display device. The display device exemplified below includes a light source and the optical sheet described above. A PDP etc. can be illustrated as a light source. A display device can be configured by bonding the above-described optical sheet to the image light emitting side of the light source via an adhesive layer or the like.

  FIG. 12 is an exploded perspective view schematically showing a plasma television 100 which is a display device according to one embodiment. In FIG. 12, the upper right side of the drawing shows the observer side, and the lower left side of the drawing shows the back side. As can be seen from FIG. 12, the plasma television 100 includes a PDP unit 101 that is a video source unit inside a casing formed by a front casing 103 and a rear casing 102. The PDP unit 101 includes a PDP and an optical sheet from the back side of the plasma television 100 toward the viewer side, and the optical sheet is bonded to the PDP with an adhesive layer. The optical sheet is the optical sheet described above. The PDP is a plasma display panel, which is a flat image light source, and the one used for a normal plasma television can be applied as it is. Accordingly, like a normal PDP, pixels each having three primary color phosphors as one unit are arranged in parallel vertically and horizontally, and an electrode for causing gas discharge to emit light is provided.

  In addition to the PDP unit 101, the plasma television 100 is provided with usual devices included in the plasma television. Examples thereof include various electric circuits and cooling means.

  Here, a plasma television is exemplified as the display device. For example, a liquid crystal display (LCD), an electroluminescence display (FED), a surface conduction electron-emitting device display (SED), an organic EL, etc., which are generally known as light sources. It is also possible to use.

  The above-described optical sheet has high productivity and can control the path of transmitted light. Therefore, the display device provided with the optical sheet has high productivity, and the display device can provide controlled light to the observer.

10, 20, 30, 40, 50 Optical sheet 11 First base layer 12 First optical functional layer 13, 23 Light transmitting portion 14, 24 Light absorbing portion 17 Light reducing layer 18 Second base layer 19 AG Layer 22 Second optical functional layer

Claims (5)

An optical sheet provided with a plurality of layers, arranged on the observer side from the light source, and controlling the light emitted from the light source to emit to the observer side,
A first optical functional layer provided with a light transmission part that can transmit light, and a light absorption part that is formed between the light transmission parts and that can absorb light, arranged in parallel along the sheet surface; and A light reducing layer capable of attenuating transmitted light,
An optical sheet in which a ratio (d / w) between a depth (d) in the layer thickness direction of the light absorbing portion and an interval (w) between the light absorbing portions arranged in parallel is 3 or less. A second optical functional layer further comprising: a light transmissive portion that can transmit light; and a light absorbing portion that is formed between the light transmissive portions and that can absorb light; Prepared,
The parallel direction of the light transmission part of the first optical functional layer and the parallel direction of the light transmission part of the second optical functional layer intersect as viewed from the normal direction of the sheet surface. The optical sheet according to 1.   The parallel direction of the light transmission part of the first optical function layer and the parallel direction of the light transmission part of the second optical function layer are orthogonal to each other as viewed from the normal direction of the sheet surface. 2. The optical sheet according to 2.   The optical sheet according to claim 1, wherein the dimming layer is provided on a side closer to the observer than the first optical functional layer. A display device comprising: a light source; and an optical sheet that is disposed closer to the viewer than the light source and controls the light emitted from the light source to be emitted toward the viewer.
An optical functional layer, wherein the optical sheet includes a light transmissive portion that transmits light and is arranged along the sheet surface, and a light absorbing portion that is formed between the light transmissive portions and can absorb light. And a light reducing layer capable of attenuating transmitted light,
The display device, wherein a ratio (d / w) between a depth (d) in the layer thickness direction of the light absorbing portion and an interval (w) between the light absorbing portions arranged in parallel is 3 or less.

Images