JP6347650B2 - Prism sheet - Google Patents

Prism sheet Download PDF

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JP6347650B2
JP6347650B2 JP2014080644A JP2014080644A JP6347650B2 JP 6347650 B2 JP6347650 B2 JP 6347650B2 JP 2014080644 A JP2014080644 A JP 2014080644A JP 2014080644 A JP2014080644 A JP 2014080644A JP 6347650 B2 JP6347650 B2 JP 6347650B2
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light
prism
surface
prism sheet
plane
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JP2015200836A (en
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一兵 今川
一兵 今川
直樹 武蔵
直樹 武蔵
育夫 三村
育夫 三村
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日本カーバイド工業株式会社
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Description

  The present invention relates to a prism sheet used in a backlight portion of a liquid crystal display device.

  The liquid crystal display device mainly includes a backlight portion and a liquid crystal display element portion. As the backlight unit, an edge light system in which a light source is arranged on the side end face of the light guide is often used from the viewpoint of making the liquid crystal display device compact.

  A general edge light type backlight unit includes a light source, a light source disposed on a side end surface, a light guide that guides and emits light from the light source, and a back surface of the light guide. A reflector that reflects light leaked from the light body, a prism sheet that is disposed on the light exit surface side of the light guide, and that collects light emitted from the light guide, and a prism sheet that is disposed on the light exit surface side of the prism sheet. And a light diffusion sheet for diffusing light emitted from the sheet.

  The prism sheet refracts or reflects the light emitted from the light guide, condenses the light on the liquid crystal panel side of the liquid crystal display element unit, and is perpendicular to the surface of the liquid crystal panel (hereinafter referred to as “front direction”). ")").

As such a prism sheet, Patent Document 1 discloses a prism sheet having a prism array in which a plurality of triangular prism unit prisms are arranged in parallel on a light incident surface. The unit prism of this prism sheet is composed of a first inclined surface on which light is incident and a second inclined surface that is composed of a plurality of planes having different inclination angles and reflects the incident light. The plurality of planes constituting the second inclined surface are formed so that the inclination angle becomes larger toward the bottom surface of the unit prism.
JP 2012-234117 A

  However, since the prism sheet of Patent Document 1 has a reflective surface composed of a plurality of flat surfaces, the luminance in the front direction may be insufficient.

  The condensing performance of the prism sheet is mainly influenced by the dimensional accuracy of the second inclined surface of the unit prism serving as the reflecting surface. Therefore, when the reflecting surface is composed of a plurality of planes, each plane requires a predetermined dimensional accuracy. There is a possibility that the desired light collection performance cannot be obtained and the luminance in the front direction cannot be improved.

  Moreover, in the prism sheet of the above-mentioned patent document 1, since the portion located on the bottom side of the unit prism among the first slope and the second slope does not contribute much to the light collection, there is room for improvement in luminance improvement in the front direction. is there.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a prism sheet capable of improving the luminance in the front direction.

  In order to solve the above problems, the prism sheet of the present invention is a prism sheet having a prism layer in which a plurality of unit prisms each having a substantially triangular prism shape are arranged in parallel on the light incident side, and each unit prism includes the prism sheet. In a cross section cut in parallel with the parallel direction of the unit prism, the unit prism has a first prism surface on which light is incident and a second prism surface that reflects the incident light, and the first prism surface is formed on the unit prism. A tip plane having an apex as an end, an intermediate plane arranged continuously to the tip plane and having a larger inclination angle than the tip plane, and a bottom portion of the unit prism as an end, from the tip plane and the intermediate plane A bottom plane having a small inclination angle, and the second prism surface is a single plane.

In this way, by configuring the second prism surface as a reflection surface with a single plane, a reflection surface with excellent dimensional accuracy can be obtained.
Therefore, the first prism surface as the incident surface is constituted by three or more planes, and the second prism surface is constituted by one plane, whereby incident light is efficiently refracted and condensed by the first prism surface. Since the light is reflected by the highly accurate second prism surface, the luminance in the front direction can be improved.
In addition, by making the inclination angle of the bottom plane smaller than the inclination angle of the tip plane and the intermediate plane, it becomes possible to collect the light incident in the vertical direction on the prism sheet, which has been difficult to collect until now. The brightness in the front direction can be improved.

  As described above, according to the present invention, a prism sheet capable of improving the luminance in the front direction is provided.

The fragmentary sectional view showing one embodiment of the prism sheet of the present invention. Sectional drawing which shows one Embodiment of the surface light source device of this invention.

Hereinafter, embodiments according to the prism sheet and the surface light source device of the present invention will be described with reference to the drawings. FIG. 1 is a partial sectional view showing an embodiment of the prism sheet of the present invention, and FIG. 2 is a sectional view showing an embodiment of the surface light source device of the present invention.
In addition, this invention is not limited to these, In the range of the objective of this invention, it can implement by adding a change suitably.

(Surface light source device 5)
As shown in FIG. 2, the surface light source device 5 of the present invention includes a light guide 3 having at least one side end surface as a light incident surface 3a and a light exit surface 3b at one surface substantially orthogonal to the light incident surface 3a. The light source 2 disposed opposite to the light incident surface 3a of the light body 3 and the reflector 4 disposed opposite to the back surface of the light exit surface 3b of the light guide 3 (surface opposite to the light exit surface 3b). And the prism sheet 1 disposed to face the light exit surface 3b of the light guide 3.

(Light source 2)
The light source 2 is a linear light source, and for example, a fluorescent lamp or LED illumination can be used.

(Light guide 3)
The light guide 3 is plate-shaped and has four side end surfaces. Of the four side end surfaces, at least one side end surface is defined as a light incident surface 3a. The light incident surface 3 a is arranged to face the light source 2, and light emitted from the light source 2 enters the light guide 3 from the light incident surface 3 a. The two main surfaces substantially orthogonal to the light incident surface 3a of the light guide 3 are opposed to each other, and one of the surfaces is the light exit surface 3b. Then, on at least one of the light exit surface 3b and the back surface, a lens array extending in a direction parallel to the light entrance surface 3a of the light guide 3 is formed in parallel, or these surfaces are roughened to provide a light exit surface. Directive light is emitted from 3b.

  The light guide 3 is not limited to a plate shape as shown in FIG. 2, but can have various shapes such as a wedge shape and a hull shape.

  The light guide 3 can be made of a translucent resin having a high light transmittance. Examples of such translucent resins include methacrylic resins, acrylic resins, polycarbonate resins, polyester resins, vinyl chloride resins, and the like.

(Reflector 4)
The reflector 4 reflects the light leaked from the light guide 3 without being reflected by the back surface of the light guide 3, and again enters the light guide 3 from the back surface, and faces the back surface of the light guide plate 3. Are arranged as follows. As the reflector 4, a plastic sheet having a metal-deposited reflective layer on the surface, a diffusing material-containing plastic sheet, or the like can be used.
Further, as the reflector 4, instead of the reflection sheet as shown in FIG. 2, a reflection layer may be formed on the back surface of the light guide 3 by metal vapor deposition or the like.

(Prism sheet 1)
The prism sheet 1 concentrates the light emitted from the light exit surface 3b of the light guide plate 3 toward the liquid crystal panel and increases the luminance in the front direction, and is disposed so as to face the light exit surface 3b of the light guide plate 3. Is done. The prism sheet 1 includes a prism layer 11 disposed on the light output surface 3 b side of the light guide plate 3 and a light diffusion layer 12 laminated on the light output side interface of the prism layer 11.

(Prism layer 11)
As shown in FIG. 1, the prism layer 11 is a layer disposed on the light incident side of the prism sheet 1, and is a layer in which a plurality of unit prisms 20 each having a substantially triangular prism shape are arranged in parallel. Each unit prism 20 includes a first prism surface 30 on which light is incident and a second prism surface 40 that reflects incident light in a cross section obtained by cutting the prism sheet 1 in parallel with the parallel direction of the unit prisms 20. Is done.
The first prism surface 30 includes a tip plane 31 having the apex 21 of the unit prism 20 as an end, an intermediate plane 32 that is arranged continuously with the tip plane 31 and has a larger inclination angle θ2 than the tip plane 31, and the unit prism 20. The bottom portion 22 is an end portion, and a tip plane 31 and a bottom plane 33 having an inclination angle θ3 smaller than the intermediate plane 32 are configured.
The second prism surface is composed of one plane.
The inclination angle is an angle between each plane and the bottom surface of the unit prism 20 or a surface parallel to the bottom surface.

In this way, by configuring the second prism surface 40 serving as a reflection surface with a single plane, it is possible to obtain a reflection surface with excellent dimensional accuracy.
Accordingly, the first prism surface 30 serving as the incident surface is configured by three or more planes, and the second prism surface 40 is configured by one plane, whereby the incident light is efficiently refracted and reflected by the first prism surface 30. Since the light is condensed and reflected by the highly accurate second prism surface 40, the luminance in the front direction can be improved.
Further, by making the inclination angle θ3 of the bottom plane 33 smaller than the inclination angle θ1 of the front end plane 31 and the inclination angle θ2 of the intermediate plane 32, it is perpendicular to the prism sheet 1 (thickness) that has been difficult to collect light until now. Direction), it is possible to collect light incident in the direction), so that the luminance in the front direction can be improved.

The first prism surface may be constituted by four or more planes as necessary. In that case, another new plane can be provided between the intermediate plane 32 and the bottom plane 33.
It is also possible between the bottom 2 2 of the adjacent unit prism 20, to provide a new planar surface.

The prism layer 11 can be made of a light transmissive resin having a high light transmittance. Examples of such translucent resins include methacrylic resins, acrylic resins, polycarbonate resins, polyester resins, vinyl chloride resins, and the like.

(Light diffusion layer 12)
The light diffusion layer 12 is a layer for diffusing light, and is disposed on the light output side of the prism sheet 1. The light diffusion layer 12 is laminated on the prism layer 11 in a state where the light-transmitting fine particles are dispersed in the light-transmitting resin.

Examples of the translucent resin constituting the light diffusion layer 12 include the same resins as those used for the prism layer 11.
As the light-transmitting fine particles, light-transmitting fine particles generally used for light diffusion sheets are used. For example, methacrylic resin beads, acrylic resin beads, polycarbonate beads, polyurethane beads, polystyrene beads, amino-based particles Resin beads, calcium carbonate beads, silica beads and the like can be mentioned.

  The formation method of the light-diffusion layer 12 is not specifically limited, A conventionally well-known method can be used. For example, a method of forming the light diffusion layer 12 by applying a resin liquid in which translucent fine particles are dispersed to the prism layer 11 and drying it, and then thermally curing a layer made of the resin liquid can be mentioned.

  The light diffusion layer 12 may not be integrated with the prism sheet but may be a light diffusion sheet that is a separate member from the prism sheet.

(Method for manufacturing prism sheet 1)
The manufacturing method of the prism sheet of this invention is not specifically limited, A conventionally well-known method can be used.
For example, by pressing a mold having a shape obtained by inverting the unit prism shape against a resin sheet for forming a prism sheet and heat-pressing, the shape pattern is transferred and cooled, and then the mold is peeled off. And a method of obtaining a prism sheet.
In addition, a unit prism forming resin material such as an ultraviolet curable resin is placed in a mold having a shape obtained by inverting the unit prism shape, and a light transmissive base sheet is stacked on the mold, and light transmissive properties are obtained using a laminator or the like. There is a method of obtaining a prism sheet by pressing the base sheet to the unit prism forming resin material, curing the unit prism forming resin material with ultraviolet rays or the like, and peeling the mold.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

― Production of prism sheet ―
The prism sheet of the example was produced by the following procedure.
(1) With respect to 100 parts by weight of a solid content of an acrylic resin having a refractive index of 1.49 (manufactured by Mitsubishi Rayon Co., Ltd .: Dianar LR275), the average particle diameter is 1.78 μm as a translucent fine particle, and the refractive index is 1.66 30 parts by weight of an amino resin particle (Epester MS benzoguanamine / formaldehyde condensate manufactured by Nippon Shokubai Co., Ltd.) is diluted with a mixed solvent in which methyl ethyl ketone and isopropyl alcohol have the same weight so that the solid content is 20% by weight. Then, it was dispersed with a high speed mixer for 60 minutes to prepare a coating solution.
(2) Next, this coating solution was applied to a polycarbonate film (manufactured by Mitsubishi Engineering Plastics, trade name: Iupilon FE-2000B, thickness: 75 μm) using a 2 mil applicator and dried at 100 ° C. for 5 minutes. Thus, a two-layer film composed of a light diffusion layer having a thickness of 10 μm and a polycarbonate layer was obtained.
(3) Further, the above two-layer film is compression molded using a molding die under the conditions of a molding temperature of 170 ° C. and a molding pressure of 9.8 MPa, and the film is cooled to 70 ° C. under pressure and taken out. Thus, a prism sheet having a structure shown in FIG. 2 composed of a light diffusion layer and a prism layer was obtained.

<Dimensions of prism sheet>
-Prism sheet thickness: 80.70 μm
-Light diffusion layer thickness: 8.00 μm
-Height H of unit prism 20: 11.40 μm
・ Pitch P of unit prism 20: 15.52 μm
-Height h1 of the tip flat surface 31: 2.0 μm
-Height h2 of the intermediate plane 32: 6.4 μm
-Height h3 of the bottom flat surface 33: 3.0 μm
-Angle β1 of the tip plane surface 31: 33.25 °
The angle β2 of the intermediate plane 32: 30.25 °
-Angle β3 of bottom plane 33: 45.00 °
The angle α of the second prism surface 40: 33.25 °

  The prism sheet of the example was measured and evaluated for the front brightness and the difficulty of seeing scratches (optical defects). As a result, the brightness in the front direction could be improved and the scratches could not be seen easily.

DESCRIPTION OF SYMBOLS 1 ... Prism sheet 2 ... Light source 3 ... Light guide 4 ... Reflector 5 ... Surface light source device 11 ... Prism layer 12 ... Diffusion layer 20 ... Unit prism 30 ... first prism surface 31 ... tip plane 32 ... intermediate plane 33 ... bottom plane 40 ... second prism surface

Claims (4)

  1. A prism sheet having a prism layer in which a plurality of substantially prismatic unit prisms are arranged in parallel on the light incident side,
    Each of the unit prisms has a first prism surface on which light is incident and a second prism surface that reflects the incident light in a cross section obtained by cutting the prism sheet in parallel with the parallel direction of the unit prisms.
    The first prism surface is
    A tip plane with the apex of the unit prism as an end; and
    An intermediate plane that is arranged continuously with the tip plane and has a larger inclination angle than the tip plane;
    The bottom of the unit prism is an end, and the bottom plane has a smaller inclination angle (except for the case of 0 °) than the tip plane and the intermediate plane,
    The prism sheet, wherein the second prism surface is a flat surface.
  2. The prism sheet according to claim 1, wherein the prism layer has a flat surface between the bottoms of the unit prisms adjacent to each other.
  3. The prism sheet according to claim 1 or 2 , wherein a light diffusion layer in which translucent fine particles are dispersed in a translucent resin is laminated on the light output side of the prism layer.
  4. A light guide having a light source, a light incident surface on which light emitted from the light source is incident, and a light output surface that guides and emits the incident light, and disposed on the opposite side of the light output surface of the light guide a reflector that is, the surface light source device and a prism sheet according to claim 1 to 3 which is disposed opposite the light exit surface of the light guide.
JP2014080644A 2014-04-10 2014-04-10 Prism sheet Active JP6347650B2 (en)

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Application Number Priority Date Filing Date Title
JP2014080644A JP6347650B2 (en) 2014-04-10 2014-04-10 Prism sheet

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Application Number Priority Date Filing Date Title
JP2014080644A JP6347650B2 (en) 2014-04-10 2014-04-10 Prism sheet

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JP6347650B2 true JP6347650B2 (en) 2018-06-27

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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997017631A1 (en) * 1995-11-06 1997-05-15 Seiko Epson Corporation Illuminator, liquid crystal display using the illuminator and electronic device
JPH11345513A (en) * 1998-06-03 1999-12-14 Shimada & Co Ltd Backlight device
JP2000231103A (en) * 1999-02-09 2000-08-22 Mitsubishi Rayon Co Ltd Lens sheet and back light and liquid crystal display device using the same
TW200606523A (en) * 2004-05-18 2006-02-16 Samsung Electronics Co Ltd Liquid crystal display and reflecting member for the same
JP2008134631A (en) * 2006-11-01 2008-06-12 Mitsubishi Rayon Co Ltd Lens sheet, surface light source device and liquid crystal display device

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