JP2014092760A - Optical sheet and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet which is capable of brightening an image emitted to the front by enhancing utilization efficiency of light from a light source when mounted on a viewer side of a display device and which can be manufactured at a low cost, and to provide a display device having the same.SOLUTION: There is provided an optical sheet which is to be mounted on a viewer side of a display device to control image light to be emitted from the display device before emitting to the viewer side, and includes a sheet of light-transmissive base material layer and a first light scattering layer for scattering light formed on one surface of the base material layer. The first light scattering layer comprises a plurality of light transmitting sections which are juxtaposed to each other along the sheet surface to transmit light and light scattering sections which are arranged between each pair of the plurality of light transmitting sections to scatter light. A display device equipped with the optical sheet is also provided.

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 related to the optical sheet, for example, Patent Document 1 includes a light transmission portion and a reflection portion that reflects a part of light incident from the light incident surface of the light transmission portion so as to be emitted from the light emission surface. A light beam direction control sheet (optical sheet) is disclosed, in which the reflecting portion is reflected so that the light incident angle on the light incident surface is smaller than the light incident angle on the light incident surface. Further, Patent Document 2 has a plurality of layers, and at least one of the plurality of layers is arranged in parallel along the sheet surface so as to be able to transmit light, and a prism portion having a trapezoidal cross-sectional shape ( There is disclosed a light control sheet (optical sheet) which is an optical function sheet layer including a light transmitting portion) and a light absorbing portion formed by filling a light-absorbing material between the prism portions. Yes.

JP 2004-12918 A JP 2010-217871 A

  According to the techniques disclosed in Patent Documents 1 and 2, it is considered that the traveling direction of the light from the light source can be controlled while suppressing the loss of light generated when the light from the light source passes through the optical sheet to some extent. However, in the optical sheet disclosed in Patent Document 1, the reflection layer is formed on the interface (slope) between the light transmission part and the reflection part. As described in the example, a process such as vapor deposition is required. Therefore, the optical sheet disclosed in Patent Document 1 is difficult to manufacture at a low cost. Moreover, since the optical sheet disclosed in Patent Document 2 absorbs the light incident on the light absorbing portion, the light from the light source may not be fully utilized.

  Accordingly, the present invention provides an optical sheet that can increase the use efficiency of light from a light source when it is arranged on the viewer side of a display device, brighten an image emitted to the front, and can be manufactured at low cost, and It is an object to provide a display device including an optical sheet.

  The present invention will be described below.

  The invention according to claim 1 is an optical sheet that is arranged on the viewer side of the display device, controls the image light emitted from the display device, and emits the light to the viewer side, and has translucency. And a first light scattering layer formed on one surface of the base material layer for scattering light, the first light scattering layers being arranged in parallel along the sheet surface An optical sheet having a plurality of light transmission portions that transmit light and a light scattering portion that is disposed between the plurality of light transmission portions and scatters light.

  According to a second aspect of the present invention, in the optical sheet of the first aspect, in the first light scattering layer, the refractive index of the light scattering portion is lower than the refractive index of the light transmitting portion.

  According to a third aspect of the present invention, in the optical sheet according to the first or second aspect, the light transmitting portion provided in the first light scattering layer transmits the light without scattering.

  In the present invention, “transmits without scattering light” means that it is formed without intentionally adding a material that scatters light, and inevitably has a slight amount of light when it is transmitted. Scattering is allowed to occur.

  According to a fourth aspect of the present invention, in the optical sheet according to any one of the first to third aspects, a plurality of light transmission parts that transmit light and are arranged in parallel along the sheet surface, and the plurality of light transmission parts A second light scattering layer disposed between and having a light scattering portion that scatters light, wherein the light transmission portion of the first light scattering layer is arranged in parallel with the light transmission portion of the second light scattering layer. The parallel direction of the portions intersects when viewed from the normal direction of the sheet surface.

  The invention according to claim 5 is the optical sheet according to claim 4, wherein the parallel direction of the light transmission part of the first light scattering layer and the parallel direction of the light transmission part of the second light scattering layer are: They are orthogonal when viewed from the normal direction of the sheet surface.

  According to a sixth aspect of the invention, in the optical sheet of the fourth or fifth aspect, in the second light scattering layer, the refractive index of the light scattering portion is lower than the refractive index of the light transmitting portion.

  According to the seventh aspect of the present invention, the light transmitting portion provided in the second light scattering layer transmits light without scattering.

  The invention according to claim 8 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 image light emitted from the light source to be emitted toward the viewer. An optical sheet includes a sheet-like base material layer having translucency, and a first light scattering layer that is formed on one surface of the base material layer and scatters light. A display device, wherein the light scattering layer includes a plurality of light transmission portions that transmit light and are arranged along the sheet surface, and a light scattering portion that is disposed between the plurality of light transmission portions and scatters light. It is.

  The optical sheet of the present invention can suppress the viewing angle of the display device to some extent when it is arranged on the viewer side of the display device, or an image emitted to the front with increased light use efficiency from the light source Can brighten. Further, the optical sheet of the present invention can be manufactured at a low cost.

It is thickness direction sectional drawing which showed the layer structure of the optical sheet 10a roughly. It is thickness direction sectional drawing which showed the layer structure of the optical sheet 10b roughly. 2 is a cross-sectional view in the thickness direction schematically showing the layer configuration of the optical sheet 20. FIG. It is the schematic which looked at the optical sheet 20 from the observer's side front (sheet surface normal line direction). 3 is an exploded perspective view schematically showing the display device 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.

  FIG. 1 is a cross-sectional view in the thickness direction schematically showing the layer structure of an optical sheet 10a which is an embodiment of the optical sheet of the present invention. In FIG. 1, for ease of viewing, some of the repeated symbols are omitted (the same applies to the following drawings).

  The optical sheet 10a is a sheet-like member that appropriately controls image light emitted from the display device and emits the image light to the viewer side when placed on the viewer side of the display device. 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 10a is a laminated sheet having the light scattering layer 12a, the base material layer 11, and the AG layer 15 from the light source side. Each layer will be described below.

  The base material layer 11 is a layer serving as a base material for forming a light scattering layer 12a described in detail later. The main component of the material which comprises the 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 base material layer 11 include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, terephthalic acid-isophthalic acid-ethylene glycol copolymer, terephthalic acid-cyclohexanedimethanol-ethylene. Polyester resins such as glycol copolymers, polyamide resins such as nylon 6, polyolefin resins such as polypropylene and polymethylpentene, acrylic resins such as polymethyl methacrylate, styrene resins such as polystyrene and styrene-acrylonitrile copolymers Examples thereof include a resin, a cellulose resin such as triacetyl cellulose, an imide resin, and a polycarbonate resin. Among these, PET is preferable from the viewpoints of mass productivity, price, availability, etc. in addition to performance. In addition to the main components, other resins and various additives may be appropriately added to the resin constituting the 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 base material layer 11 is not particularly limited, but when PET is the 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 light scattering layer 12a has a light transmission part 13 and a light scattering part 14a. The light scattering layer 12a has the cross section shown in FIG. 1 and extends to the back / near side of the drawing. That is, the light transmitting portion 13 and the light scattering portion 14a have a cross section shown in FIG. 1 and are arranged so as to extend in one direction along the sheet surface, and along the sheet surface in a direction different from the one direction. A plurality of light transmission portions 13 are arranged. The light scattering portion 14 a is disposed between the light transmission portions 13.

  The light transmitting portion 13 is a portion that transmits light, and the light transmitting portion 13 is preferably a portion that transmits light without scattering. Here, “transmits without scattering light” means a part formed without intentionally adding a material that scatters light, and is unavoidable when light passes through the material. Some scattering is allowed. Further, the surface of the light transmission part 13 on the base material layer 11 side and the opposite side surface (surface on the light source side) are formed in parallel.

  The material constituting the light transmission part 13 may be the same as or different from that of the base material layer 11. However, if there is a difference in refractive index between the two, the possibility of light being deflected at the interface increases, so even if they are the same material or different materials, the refractive index difference is small or there is no refractive index difference. It is preferable.

  When the light transmission part 13 and the base material layer 11 are comprised with the same material, the base material layer 11 and the light transmission part 13 can also be formed integrally. Further, even when the light transmission part 13 and the base material layer 11 are made of different materials, and even when the light transmission part 13 and the base material layer 11 are made of the same material, the base material layer 11 and the light transmission part 13 are separately formed, May be laminated. A specific example of a method for forming the light transmission portion 13 will be described later.

The light transmission portion 13 has a refractive index of N _p, having optical transparency. Examples of the material constituting the light transmitting portion 13 include a transparent resin mainly composed of one or more of acrylic, styrene, polycarbonate, polyethylene terephthalate, acrylonitrile, and an epoxy acrylate or urethane acrylate reactive resin. (Ionizing radiation curable resin and the like). 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.

  The light scattering portion 14a is configured to be able to scatter the reached light. Details are as follows.

  As described above, the light transmission portions 13 are arranged in parallel in the direction along the sheet surface at a predetermined interval, and a concave portion having a trapezoidal cross section is formed between the light transmission portions 13. The concave portion in the present embodiment is a groove having a trapezoidal cross section whose width becomes narrower from the light source side to the observer side in the cross section (sheet thickness direction cross section) shown in FIG. The light scattering portion 14a is formed by filling the material constituting the light scattering portion 14a. Therefore, the light scattering portion 14a also has a trapezoidal cross section along the recess.

Of the trapezoidal cross section of the light scattering portion 14a, the angle θ ₁ (see FIG. 1) of the hypotenuse constituting the leg portion with respect to the sheet surface normal is preferably 0 ° or more and 20 ° or less. The angle θ ₁ with respect to the sheet surface normal is less than 0 ° (in this embodiment, θ ₁ is negative means that in the cross section shown in FIG. 1, the light scattering side 14a has a light source side with respect to the width of the bottom on the base material layer 11 side. If the light scattering portion 14a is formed so that the bottom width of the light scattering layer 12a is formed, it becomes difficult to produce a mold used for forming the light scattering layer 12a. However, the mold release property of the molded material is deteriorated. On the other hand, if θ ₁ is too large, it is difficult to increase the aspect ratio of the depth of the recess to the opening width of the recess formed between the light transmission portions 13, and a desired effect described later by the light scattering layer 12a is reduced. There is a fear.

However, in the present invention, the shapes of the light transmitting part and the light scattering part are not limited to the form illustrated in FIG. The light transmission part should just be formed in parallel with the surface at the side of a base material layer, and the surface on the opposite side. Accordingly, in the cross section corresponding to the cross section shown in FIG. 1, the light transmitting portion and the light scattering portion may be rectangular (when θ ₁ = 0 °), and the portion corresponding to the trapezoidal leg of the light scattering portion. Is curved (the tangent of the curve is preferably 0 ° or more and 20 ° or less similarly to θ _{1 in} each part) or broken line (each line constituting the broken line is 0 ° or more and 20 similarly to θ ₁ described above) It is preferable that the angle is less than or equal to °.

  From the viewpoint of facilitating light scattering at the interface between the light scattering portion 14a and the light transmission portion 13, the surface between the light scattering portion 14a and the light transmission portion 13 is formed with an infinite number of minute irregularities. It is good also as a mat surface.

  The pitch at which the light scattering portions 14a are arranged in parallel is not particularly limited, but is preferably 10 μm or more and 200 μm or less. If the pitch of the light scattering portions 14a is too narrow, the effects described later by the light scattering layer 12a may be reduced, and processing becomes difficult because the shape becomes fine. On the other hand, if the pitch of the light scattering portions 14a is too wide, the releasability of the material tends to decrease when molding with a mold.

  Of the trapezoidal cross section of the light scattering portion 14a, the width on the light source side is not particularly limited, but is preferably 5 μm or more and 150 μm or less. If this width is too narrow, the effects described later by the light scattering layer 12a may be reduced, and processing becomes difficult because the shape becomes fine. On the other hand, if this width is too wide, the releasability of the material tends to decrease when molding with a mold.

Light scattering portion 14a, it is constituted by a predetermined material having a lower refractive index N _b than the refractive index N _p of the light transmitting portion 13 is preferred. The refractive index _{N b} of the refractive index _{N p} and the light scattering portion 14a of the light transmitting portion ₁₃ may be a N p = _{N b,} when the N p> _{N b,} the light transmitting portion 13 and the light-scattering Based on the relationship between the refractive index difference and the incident angle to the interface, the light reaching the interface is totally reflected at the interface with the portion 14a, and the interface is reflected at an angle less than the critical angle. Can reach the light scattering portion 14a and be scattered as will be described later. Thus, by totally reflecting or scattering the light incident on the light scattering layer 12, the amount of light emitted from the optical sheet 10 at an angle close to parallel to the normal direction of the sheet surface can be increased. The difference in refractive index between N _p and N _b is not particularly limited, is preferably 0.06 or less greater than 0.

The scattering reflection part 14a can scatter-reflect light by containing the material which reflects and scatters light. Examples of the material constituting the scattering reflection portion 14a include a curable resin mixed with a white pigment or a silver pigment. In this case, the refractive index of the curable resin is an N _b. Examples of the white pigment used for the scattering reflection portion 14a include metal oxides such as titanium oxide, titanium dioxide, magnesium oxide, and zinc oxide. As a silver pigment, metals, such as aluminum and chromium, are mentioned, for example. Thereby, light can be efficiently scattered and reflected. Moreover, the curable resin can use the same material as that constituting the light transmitting portion 13. The scattering reflection part 14a can be formed by filling the recesses between the light transmission parts 13 with the material as described above.

  Although the thickness of the light-scattering layer 12a is not specifically limited, It is preferable that they are 10 micrometers or more and 200 micrometers or less. If the light scattering layer 12a is too thin, the height (size in the thickness direction) of the light scattering portion 14a is insufficient and the desired optical effect is reduced, or the processing itself of the light scattering portion 14a becomes difficult. There is a risk of doing. On the other hand, if the light-scattering layer 12a is too thick, the light-scattering portion 14a is too high, and the production of the mold and the releasability of the material from the mold are lowered, and the productivity may be deteriorated. .

  Next, the AG layer 15 will be described. AG means anti-glare, and the AG layer 15 is a layer having a function capable of preventing glare when an observer looks at the screen. The AG layer 15 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 10a will be described.

  The light scattering layer 12a is formed by a method using a mold roll. That is, a mold roll is prepared in which irregularities capable of transferring the shape of the light transmitting portion 13 of the light scattering layer 12a are provided on the outer peripheral surface of the cylindrical roll. And the base material used as the base material layer 11 is inserted between a die roll and the nip roll arrange | positioned so as to oppose this. At this time, the AG layer 15 is preferably formed in advance on one surface of the substrate. The mold roll and the nip roll are rotated while supplying the composition constituting the light transmitting portion 13 between the surface of the substrate where the AG layer 15 is not formed and the mold roll. As a result, the concave / convex concave portions formed on the surface of the mold roll are filled with the composition constituting the light transmitting portion 13, and the composition conforms to the concave / convex surface shape of the mold roll.

  Here, as a composition which comprises the light transmissive part 13, although what was mentioned above is preferable, it is as follows more specifically. That is, the photocurable resin composition which mix | blended the reactive dilution monomer (M1) and the photoinitiator (I1) with the photocurable prepolymer (P1) can be 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.

  Examples of the photopolymerization initiator (I1) include hydroxybenzoyl compounds (2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, benzoin alkyl ether, etc.), benzoyl Formate compounds (such as methylbenzoylformate), thioxanthone compounds (such as isopropylthioxanthone), benzophenone compounds (such as benzophenone), phosphate compounds (1,3,5-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6) -Trimethylbenzoyl) -phenylphosphine oxide, etc.), benzyldimethyl ketal and the like. Among these, the irradiation device for curing the photocurable resin composition and the curability of the photocurable resin composition can be arbitrarily selected. From the viewpoint of preventing coloring of the light transmitting portion 116, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone and bis (2,4,6-trimethylbenzoyl) are preferable. ) -Phenylphosphine oxide.

  These photocurable prepolymer (P1), reactive diluent monomer (M1) and photopolymerization initiator (I1) can be used alone or in combination of two or more.

  Light is irradiated from the base material side by a light irradiation device to the composition constituting the light transmission portion 13 sandwiched between the mold roll and the base material and filled therein. Thereby, the composition which comprises the light transmissive part 13 can be hardened, and the shape can be fixed. And the base material layer 11 and the shape | molded light transmission part 13 are released from a metal mold | die roll with a mold release roll.

Next, the light scattering portion 14 a can be formed by filling the concave portions formed between the light transmission portions 13 with the composition constituting the light scattering portion 14 a and curing it. Specifically, an ionizing radiation curable resin or other known curable resin is excessively supplied with a composition in which a material that reflects and scatters the above-described light is dispersed, and the squeegee is squeezed with a blade to remove excess. The composition is removed by scraping, and the recess is filled with the composition. An appropriate curing method is applied to the composition thus filled to cure the curable resin.
Thus, the light scattering portion 14a is formed.

  As described above, the optical sheet 10a can be easily and inexpensively manufactured without requiring a process such as vapor deposition.

  Next, an operation when the optical sheet 10a is arranged on the viewer side of the display device will be described. FIG. 1 shows a schematic optical path example. Note that the optical path example is conceptually shown, and does not strictly represent the degree of refraction or reflection. The same applies hereinafter.

  The video light L11 emitted from the light source and incident on the light transmission part 13 at a small angle with respect to the normal to the sheet surface is transmitted through the light transmission part 13, the base material layer 11 and the AG layer 15 and emitted from the optical sheet 10a. , Provided as an image to the observer. On the other hand, the image light L12 emitted from the light source and incident on the light scattering portion 14a is scattered and reflected by the light scattering portion 14a. Then, the scattered and reflected image light L12 is transmitted through the base material layer 11 and the AG layer 15 and emitted from the optical sheet 10a, and is provided as an image to the observer. According to the optical sheet 10a, the image light reaching the light scattering portion 14a is scattered and reflected without being absorbed and emitted to the viewer side, so that bright image light can be provided. That is, the image light from the light source can be efficiently emitted to the observer side. Further, the amount of light emitted from the optical sheet 10a at a small angle with respect to the sheet surface normal can be increased by scattering and reflecting the light incident on the light scattering portion 14a at a large angle with respect to the sheet surface normal. it can. That is, when the optical sheet 10a is arranged on the viewer side of the display device, the viewing angle of the display device is suppressed to some extent, and the use efficiency of light from the light source provided in the display device is enhanced to increase the front (sheet surface method). The image emitted in the vicinity of the line direction can be brightened.

  When light is totally reflected as in the technique disclosed in Patent Document 1, light emitted from the front surface of the optical sheet may appear bluish due to light wavelength dispersion. Such a change in the color of light can be suppressed by scattering and reflecting in this manner.

  Next, another embodiment of the optical sheet of the present invention will be described. FIG. 2 is a diagram illustrating the optical sheet 10b according to the second embodiment, and is a diagram corresponding to FIG. 1 of the optical sheet 10b. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

  The optical sheet 10b includes a light scattering layer 12b, a base material layer 11, and an AG layer 15. The optical sheet 10b differs from the optical sheet 10a in that a light scattering layer 12b is applied instead of the light scattering layer 12a of the optical sheet 10a. About the other point, the optical sheet 10b and the optical sheet 10a are the same.

  The light scattering portion 14a of the light scattering layer 12a provided in the optical sheet 10a scatters and reflects light, whereas the light scattering portion 14b of the light scattering layer 12b provided in the optical sheet 10b scatters while transmitting light. Therefore, the optical sheet 10b is different from the optical sheet 10a. The light scattering portion 14b is formed in the concave portion between the light transmission portions 13 in the same manner as the light scattering portion 14a. As a material constituting the light scattering portion 14b that scatters while transmitting the transmitted light, a material obtained by mixing a transparent curable resin and a transparent scattering agent having a refractive index different from that of the curable resin is preferable. Examples of the scattering agent include crosslinked particles obtained by polymerizing monomers mainly composed of (meth) acrylic acid ester and styrene. Specific examples of the cross-linked particles include Gantz Pearl manufactured by Gantz Kasei Co., Ltd. The cross-linked particles can be controlled in refractive index by changing the mixing ratio of acrylic acid ester and styrene. For example, the refractive index can be made about 1.49 by increasing the acrylic ratio, and the refractive index can be made about 1.59 by increasing the styrene ratio. Further, urethane cross-linked particles can be used as the scattering agent. Specific examples of the urethane crosslinked particles include Art Pearl manufactured by Negami Kogyo Co., Ltd. The scattering agent can also be hollow particles.

  Similarly to the optical sheet 10a, the optical sheet 10b can be easily and inexpensively manufactured without requiring a process such as vapor deposition.

  Next, an operation when the optical sheet 10b is arranged on the viewer side of the display device will be described. FIG. 2 shows a schematic optical path example.

  The video light L21 emitted from the light source and incident on the light transmission part 13 at a small angle with respect to the normal to the sheet surface is transmitted through the light transmission part 13, the base material layer 11 and the AG layer 15 and is emitted from the optical sheet 10b. , Provided as an image to the observer. Therefore, when the optical sheet 10b is arranged on the viewer side of the display device, a clear image can be seen from the front (sheet surface normal direction) of the display device. On the other hand, the image light L22 emitted from the light source and incident on the light scattering layer 12b at a large angle with respect to the normal to the sheet surface enters the light scattering portion 14b and is scattered and transmitted. According to the optical sheet 10b, when the optical sheet 10b is disposed on the viewer side of the display device by scattering light having a large angle with respect to the normal to the sheet surface as described above, the viewing angle of the display device is increased. It can be suppressed to some extent. That is, according to the optical sheet 10b, an effect of preventing so-called peeping can be exhibited.

  Next, another embodiment of the optical sheet of the present invention will be described. FIG. 3 shows a cross section of the optical sheet 20 according to the third embodiment, and is a diagram schematically showing the layer configuration.

  The optical sheet 20 is referred to as a light scattering layer 22 (hereinafter sometimes referred to as “second light scattering layer 22”) and a base material layer 21 (hereinafter referred to as “second base material layer 21”) from the light source side. ), Pressure-sensitive adhesive layer 25, light scattering layer 12a (hereinafter sometimes referred to as "first light scattering layer 12a"), substrate layer 11 (hereinafter referred to as "first substrate layer 11"). And an AG layer 15. Since the 1st light-scattering layer 12a, the 1st base material layer 11, and AG layer 15 are the same as that of the optical sheet 10 mentioned above, description is abbreviate | omitted.

  The second base layer 21 has the same configuration as the first base layer 11, and the second light scattering layer 22 has the same configuration as the first light scattering layer 12a. The light scattering part 24 of the light scattering layer 22 (only the light transmission part 23 appears in FIG. 3 but not the light scattering part 24) is orthogonal to the light scattering part 14 of the first light scattering layer 12a. It is arranged in the direction. FIG. 4 shows the relationship between the light scattering portion 14 a of the first light scattering layer 12 a and the light scattering portion 24 of the second light scattering layer 22. FIG. 4 is a schematic view of the optical sheet 20 as viewed from the front (sheet surface normal direction) on the viewer side.

  The pressure-sensitive adhesive layer 25 is a layer for bonding the second base material layer 21 and the first light scattering layer 12a. The material constituting the pressure-sensitive adhesive layer 25 is not particularly limited as long as it can adhere the second base material layer 21 and the first light scattering layer 12a, and is well-known pressure-sensitive adhesive, adhesive, photocurable. A resin, a thermosetting resin, or the like can be used. As a material constituting the pressure-sensitive adhesive layer 25, for example, an acrylic pressure-sensitive adhesive can be used, and more specifically, a pressure-sensitive adhesive combining an acrylic copolymer and an isocyanate compound can be used. However, the material constituting the pressure-sensitive adhesive layer 25 is preferably excellent in translucency and weather resistance due to the properties of the optical sheet 20.

  Although the thickness of the adhesive layer 25 is not specifically limited, It is preferable that they are 10 micrometers or more and 100 micrometers or less. By making the thickness of the pressure-sensitive adhesive layer 25 in the above range, it is easy to ensure the adhesion between the second base material layer 21 and the first light scattering layer 12a while making the thickness of the pressure-sensitive adhesive layer 25 uniform. Become.

  According to the optical sheet 20, as in the optical sheet 10, the first light scattering layer 12a reduces the viewing angle and improves the front luminance in a plane parallel to a predetermined direction (parallel direction of the light transmitting portion 13). In addition, the second light scattering 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 portions 23).

  The optical sheet 20 is a laminated sheet including the first light scattering layer 12a, the first base material layer 11 and the AG layer 15 manufactured by the same method as the optical sheet 10 described above, and then the adhesive sheet 25 is interposed therebetween. It can manufacture by bonding the lamination sheet in which the 2nd light-scattering layer 22 was formed in the one surface side of the 2nd base material layer 21. FIG. The second light scattering layer 22 can be formed in the same manner as the first light scattering layer 12a. The pressure-sensitive adhesive layer 25 is formed on the other surface side of the second base material layer 21 before forming the second light scattering layer 22 on the one surface side of the second base material layer 21. It may be formed on the surface of the first light scattering layer 12a or the second base material layer 21 when the first light scattering layer 12a and the second base material layer 21 are bonded together. When the pressure-sensitive adhesive layer 25 is made of an ultraviolet curable resin or the like, the first light scattering layer 12a and the second base material layer 21 are laminated via the pressure-sensitive adhesive layer 25 and then cured by irradiation with ultraviolet light or the like. You can do it.

  In the description of the optical sheet 20 so far, as illustrated in FIG. 4, in the front view of the optical sheet, the light scattering portion of the first light scattering layer and the light scattering portion of the second light scattering layer 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, this invention is not limited to the form which concerns, The light-scattering part of a 1st light-scattering layer and the light-scattering part of a 2nd light-scattering layer are respectively with respect to four sides of an optical sheet in the front view of an optical sheet. It may be arranged in parallel in an inclined direction. At this time, the crossing angle between the light absorbing portion of the first light scattering layer and the light absorbing portion of the second light scattering layer when the optical sheet is viewed from the front is not particularly limited. Or less, more preferably 90 °.

  In the description of the optical sheet 20 thus far, the first light scattering layer and the second light scattering layer are arranged in the same direction, that is, the base material layer is on the viewer side in both cases. Although the embodiment has been described by way of example, the present invention is not limited to such a form, and either or both of the first light scattering layer and the second light scattering layer are in the opposite form to the illustrated form. Also good.

  Further, in the description of the optical sheet 20 thus far, the embodiment including the first light scattering layer 12a and the second light scattering layer 22 has been described as an example, but the present invention is not limited to such a configuration, One or both of the first light scattering layer and the second light scattering layer may be a layer that transmits and scatters light like the light scattering layer 12b.

  In the description of the optical sheet of the present invention so far, the embodiment including the light scattering layer, the base material layer, the AG layer, and the like has been described as an example. However, the optical sheet of the present invention is not limited to such a form. As long as the effects of the optical sheet of the present invention described above are not impaired, the optical sheet of the present invention may further include other layers provided in a conventionally known optical sheet.

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

  FIG. 5 is an exploded perspective view schematically showing a plasma television 100 which is a display device according to one embodiment. In FIG. 5, 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. 5, 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 the PDP and the optical sheet of the present invention from the back side of the plasma television 100 toward the viewer side, and the optical sheet is bonded to the PDP via an adhesive layer. 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.

  The plasma television 100 includes not only the PDP unit 101 but also usual devices included in the plasma television in the casing. 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 optical sheet of the present invention described above can be manufactured at a low cost, and the path of the image light transmitted therethrough can be controlled as described above. Therefore, the display device of the present invention provided with the optical sheet can reduce the production cost, and according to the display device, it is possible to provide the observer with image light whose path is controlled.

Example 1
A polyester film (Cosmo Shine (registered trademark) A4300, thickness 100 μm, manufactured by Toyobo Co., Ltd.) was prepared as a base material layer, and a light transmitting portion was formed on one surface side of the base material layer as described above. . That is, after applying a photocurable resin composition (refractive index 1.55) to a base material layer and shaping with a predetermined mold, the photocurable resin composition is cured by irradiating with ultraviolet rays. The light transmission part was formed by releasing from the mold. Next, a light scattering portion is formed between the light transmitting portions as described above using a composition for forming the light scattering portion (20 parts of titanium oxide is mixed in a binder having a refractive index of 1.55). did. That is, the above composition for constituting the light scattering portion is excessively supplied to the concave portion formed between the light transmitting portions, the squeegee is removed by scraping with a blade, and the composition is removed in the concave portion. The light scattering portion was formed by filling and curing the composition filled in the recesses by irradiating with ultraviolet rays. Thus, an optical sheet having a base material layer and a light scattering layer formed on one surface side of the base material layer was produced. In addition, the pitch of the light transmission part in the optical sheet (see p in FIG. 1) is 105 μm, the width on the light source side of the light transmission part (see w1 in FIG. 1) is 80 μm, and the light source side of the light scattering part. The width on the side (see w2 in FIG. 1) is 25 μm, the width on the side of the light transmitting portion on the viewer side (see w3 in FIG. 1) is 100 μm, and the width on the side of the light scattering portion on the viewer side (see FIG. 1). 1) is 5 μm, the thickness of the light scattering portion (see t in FIG. 1) is 160 μm, and the angle of the hypotenuse that constitutes the leg of the trapezoidal cross section of the light scattering portion with respect to the normal to the sheet surface (θ in FIG. 1) ₁ ) was set to 1.5 degrees.

(Comparative Example 1)
An optical sheet was prepared in the same manner as in Example 1 except that 20 parts of titanium oxide used in the composition for constituting the light scattering part of Example 1 was changed to 5 parts of carbon black.

  The optical sheet of Example 1 and the optical sheet of Comparative Example 1 were each bonded and observed on the viewer side of the display using an acrylic adhesive. When an image was displayed on the display and observed, the optical sheet of Example 1 was brighter than the optical sheet of Comparative Example 1 in the front view. From this result, it is considered that the optical sheet of Example 1 can brighten the image emitted to the front by increasing the use efficiency of light from the light source than the optical sheet of Comparative Example 1.

10a, 10b Optical sheet 11 Base material layer (first base material layer)
12a Light scattering layer (first light scattering layer)
12b Light scattering layer 13 Light transmission part 14a, 14b Light scattering part 15 AG layer 20 Optical sheet 21 Base material layer (second base material layer)
22 Light scattering layer (second light scattering layer)
23 Light Transmitting Section 24 Light Scattering Section 25 Adhesive Layer 100 Plasma Television (Display Device)

Claims (8)

An optical sheet that is arranged on the viewer side of the display device and controls the image light emitted from the display device to be emitted to the viewer side,
A sheet-like base material layer having translucency;
A first light-scattering layer that is formed on one surface of the base material layer and scatters light,
The first light scattering layer is
A plurality of light transmissive portions arranged in parallel along the sheet surface to transmit light;
A light scattering portion that is disposed between the plurality of light transmission portions and scatters light,
Optical sheet.   The optical sheet according to claim 1, wherein in the first light scattering layer, a refractive index of the light scattering portion is lower than a refractive index of the light transmission portion.   The optical sheet according to claim 1, wherein the light transmission part provided in the first light scattering layer transmits without scattering light. A second light scattering layer further comprising: a plurality of light transmission parts that transmit light, and a light scattering part that is disposed between the plurality of light transmission parts and that scatters the light; Have
The parallel direction of the light transmission part of the first light scattering layer and the parallel direction of the light transmission part of the second light scattering layer intersect each other when viewed from the normal direction of the sheet surface. The optical sheet in any one of thru | or 3.   The parallel direction of the light transmission part of the first light scattering layer and the parallel direction of the light transmission part of the second light scattering layer are orthogonal to each other when viewed from the normal direction of the sheet surface. 5. The optical sheet according to 4.   The optical sheet according to claim 4 or 5, wherein in the second light scattering layer, a refractive index of the light scattering portion is lower than a refractive index of the light transmission portion.   The optical sheet according to claim 4, wherein the light transmission part provided in the second light scattering layer transmits light without scattering. 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 image light emitted from the light source to be emitted to the viewer.
The optical sheet comprises a sheet-like base material layer having translucency, and a first light scattering layer that is formed on one surface of the base material layer and scatters light,
A plurality of light transmitting parts that transmit light, the first light scattering layer being arranged in parallel along the sheet surface, and a light scattering part that is disposed between the plurality of light transmitting parts and that scatters light. A display device.

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