JP3913870B2 - Optical sheet, optical sheet laminate, surface light source device, and transmissive display device - Google Patents

Optical sheet, optical sheet laminate, surface light source device, and transmissive display device Download PDF

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Publication number
JP3913870B2
JP3913870B2 JP33166697A JP33166697A JP3913870B2 JP 3913870 B2 JP3913870 B2 JP 3913870B2 JP 33166697 A JP33166697 A JP 33166697A JP 33166697 A JP33166697 A JP 33166697A JP 3913870 B2 JP3913870 B2 JP 3913870B2
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Japan
Prior art keywords
light
surface
optical sheet
sheet
light source
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JP33166697A
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JPH11133214A (en
Inventor
啓二 鹿島
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大日本印刷株式会社
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Priority to JP9-229364 priority Critical
Priority to JP22936497 priority
Application filed by 大日本印刷株式会社 filed Critical 大日本印刷株式会社
Priority to JP33166697A priority patent/JP3913870B2/en
Priority claimed from US09/064,059 external-priority patent/US5995288A/en
Publication of JPH11133214A publication Critical patent/JPH11133214A/en
Publication of JP3913870B2 publication Critical patent/JP3913870B2/en
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical sheet composed of a prism sheet or a light diffusing sheet suitable for use as a backlight surface light source used for illuminating a translucent display such as a transmissive liquid crystal display device and an advertising board from the back, and an optical sheet The present invention relates to a laminated body, a surface light source device using the optical sheet or the optical sheet laminated body, and a transmissive display device.
[0002]
[Prior art]
In recent liquid crystal display devices, a surface light source device for illuminating the liquid crystal display device from the back side is naturally required to be thin and light as required for low power consumption, thinness and weight reduction. In order to reduce power consumption, light from the light source is effectively used to reduce power consumption in the light source.
[0003]
Based on such a request, as disclosed in, for example, JP-A-60-70601, JP-A-2-84618, JP-A-3-69184, JP-A-7-191319, etc. There is one in which light from a light source is condensed in a specific direction (in many cases, the normal direction of the light exit surface).
[0004]
As a surface light source device used for a transmissive liquid crystal display device or the like, there are an edge light type and a direct type.
[0005]
As disclosed in Japanese Patent Laid-Open No. 3-5725, an edge light type surface light source device usually receives light source light from one side end face of a plate-shaped light guide such as a transparent acrylic resin. The light from the light exit surface, which is one surface of the body, is guided, and the light is emitted from this to the back surface of the liquid crystal panel or the like.
[0006]
In this case, in order to improve the light utilization efficiency, a light reflecting plate or a light reflecting film is provided on the surface opposite to the light emitting surface of the light guide, and in order to make the emitted light uniform, for example, actual As disclosed in JP-A-5-73602 and the like, a diffusion sheet having a light diffusing action is often provided on the light exit surface side of the light guide.
[0007]
Further, as disclosed in, for example, Japanese Utility Model Laid-Open No. 2-3001, a direct type surface light source device reflects light source light to the back surface of a liquid crystal panel or the like by a reflecting plate, and a diffusion sheet is provided on the light exit surface side. Is arranged to diffuse the emitted light so that the shape of the light source cannot be identified by human eyes.
[0008]
Further, in the edge light type or direct type surface light source device as described above, the light from the surface light source is concentrated on a specific direction and emitted on the surface side of the translucent substrate as described above. Some have a prism sheet (prism film) in which a plurality of unit prisms are arranged.
[0009]
Various types of use of the prism sheet have been proposed, such as a set direction of the unit prism or lens side (prism surface) with respect to the light source side, a combination of a plurality of prism sheets, and the like.
[0010]
In any case, the prism sheet as described above often has a smooth surface on the surface (back surface) opposite to the prism surface.
[0011]
[Problems to be solved by the invention]
When the above prism sheet is combined with a light guide, a diffusion sheet, another prism sheet, etc., a repeated pattern of light and dark due to light from a surface light source is observed, and this is used, for example, in a liquid crystal display device In addition, there is a problem that an image formed from each pixel is disturbed.
[0012]
On the other hand, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-151909, the light-dark repeating pattern is obtained when, for example, two prism sheets are used, the prism surface of one prism sheet and the other prism sheet are used. A method for eliminating the interference fringes generated by an external light source has been proposed.
[0013]
However, as a result of confirmation by the present inventor, a bright and dark repetitive pattern was observed in the surface light source device even in a dark room where light from an external light source did not enter.
[0014]
That is, the present inventor has generated interference fringes by surface light source light, not by external light source light, and the interference fringes are formed on the smooth surface of the prism sheet and the smooth surface of the light guide plate, the smooth surface of the diffusion plate, or other prisms. It was confirmed that it occurred between the smooth surface of the sheet.
[0015]
On the other hand, as disclosed in the above-mentioned JP-A-7-151909, a method of forming minute irregularities satisfying a specific condition on the smooth surface of the prism sheet is also conceivable. In this case, however, the light from the surface light source is used. There is a problem in that the original function of the prism sheet, which improves the brightness by condensing light in a specific direction, for example, the normal direction of the light exit surface, is reduced.
[0016]
On the other hand, the present inventors have disclosed, in Japanese Patent Application No. 9-104554, a prism sheet, a surface light source device, and a transmission type that can suppress the generation of interference fringes without lowering the luminance on the light exit surface side. A display device was proposed.
[0017]
That is, a plurality of unit prisms are arranged on the surface of the translucent substrate, and the prism sheet with the back surface covered with a coating layer made of a translucent material, on the surface opposite to the translucent substrate of the coating layer, By providing a large number of minute hill-shaped protrusions having a protrusion height from the surface of 1 to 7 μm, the generation of interference fringes is suppressed.
[0018]
According to the present invention, it is possible to suppress the occurrence of interference fringes while suppressing a decrease in luminance on the light exit surface side of the prism sheet, but it damages the prism, the light guide plate surface, etc. in other prism sheets that are in contact with the minute hill-shaped projections. As a result, there is a problem that a uniform planar light emitting state as a whole cannot be obtained due to this wrinkle.
[0019]
In particular, when the prism portion of another prism sheet is damaged by the micro hill-like projection, the apex angle of the prism portion is 80 to 100 ° and is sharp, so that it can be removed from the micro hill-like projection during handling. There was a problem that the force was concentrated on the tip and easily damaged.
[0020]
Further, on the light emission side, the conventional prism sheet as described above is configured such that a light diffusion sheet is laminated on the prism surface side which is a light emission surface so as to hide defects (scratches, dirt, etc.) of the prism sheet. In addition, there were many cases where the directional light emission characteristics were slightly calmed.
[0021]
In the prism sheet laminated with the light diffusion sheet as described above, the prism (or lens) portion in contact with the light diffusion sheet is damaged by the irregularities on the surface of the light diffusion sheet. There is a problem that the state of light emission cannot be obtained.
[0022]
On the other hand, like the light incident surface in the above-described prism sheet, it can be considered that the prism sheet side of the light diffusion sheet is a smooth surface. For example, JP-A-7-333409 and JP-A-7- As disclosed in Japanese Patent No. 151909, etc., there is a problem that interference fringes and moire patterns occur between the smooth surface of the light diffusion sheet and the smooth surface of the light guide plate and the prism sheet. It hasn't arrived.
[0023]
The present invention has been made in view of the above-described conventional problems, and is an optical sheet that suppresses the decrease in luminance on the light-emitting surface side and the generation of interference fringes and prevents damage to other prism sheets that come into contact therewith. An object of the present invention is to provide an optical sheet laminate, a surface light source device and a transmissive display device using the same.
[0024]
[Means for Solving the Problems]
In this invention, the interference fringes generated when the surface opposite to the prism surface of the optical sheet having the prism surface is arranged adjacent to the smooth surface of the light guide plate, etc. are caused by the light from the internal light source (surface light source). In addition, in order to suppress the interference fringes, when the hill-like projections are formed on the back surface of the optical sheet, the prisms of other optical sheets are easily damaged by the tip of the hill-like projections that protrude greatly. A coating comprising a plurality of unit prisms or unit lenses arranged on the surface of the light-transmitting base material on the surface of the light-transmitting base material and having a back surface made of a light-transmitting material. In the optical sheet covered with a layer, the above-mentioned object is achieved by configuring the coating layer to include spherical beads having a half-value width of particle size distribution of 1 μm or less.
[0025]
In another invention, when the light diffusion sheet is laminated on the prism sheet, the prism (or lens) portion that is in contact with the convex and concave portions on the surface of the light diffusion sheet is damaged. In an optical sheet having a light diffusing layer on the surface of a light-transmitting substrate and covering the back surface with a coating layer made of a light-transmitting material as described in claim 1, the coating layer comprises: The object is achieved by including spherical beads having a half-value width of 1 μm or less in the particle size distribution.
[0026]
The light diffusion layer is configured to include a light transmitting spherical bead as in claim 3, and the average particle diameter of the light transmitting spherical bead in the light diffusion layer is an average of the spherical beads included in the coating layer. You may make it make it larger than a particle size.
[0027]
According to a fourth aspect of the present invention, the spherical beads contained in the coating layer may be composed of translucent beads having a particle diameter of 1 to 10 μm.
[0028]
According to the present invention, as in claim 5, a plurality of optical sheets including the unit prism or unit lens of claim 1 or 4 are laminated, and the coating layers in the laminated optical sheets are laminated adjacently. The object is achieved by an optical sheet laminate that is in contact with a unit prism or unit lens in the optical sheet.
[0029]
According to the present invention, as in claim 6, an optical sheet including the light diffusing layer according to any one of claims 2 to 4 and a plurality of prism sheets in which a plurality of unit prisms or unit lenses are arranged on the surface of the translucent substrate are laminated. Thus, the object is achieved by the optical sheet laminate, wherein the coating layer in the laminated optical sheet is in contact with a unit prism or unit lens in the prism sheet laminated adjacently. Is.
[0030]
Further, the invention according to the surface light source device is a plate-like body made of a translucent material as in claim 7, and at least light introduced from the one side end surface is transmitted from a light emission surface which is one surface. A light guide adapted to emit, a light source for allowing light to enter from at least one side surface of the light guide, provided on the light emission surface side of the light guide, and emitted from the light emission surface The above object is achieved by a surface light source device comprising: the optical sheet according to claim 1, wherein light is incident from the coating layer side.
[0031]
According to another aspect of the present invention, a light diffusing sheet, a light source for irradiating light to the light diffusing sheet, a light source disposed on the opposite side of the light diffusing sheet, and a light source A reflector that reflects light from the light diffusion sheet toward the light diffusion sheet, and an optical sheet according to any one of claims 1 to 4 disposed so that light emitted from the light diffusion sheet is incident from the coating layer The above object is achieved by a surface light source device having the above.
[0032]
Furthermore, this invention is arrange | positioned on the opposite side to the said light diffusion sheet of this light source, and the light source which irradiates light to this light diffusion sheet, and reflects the light from a light source toward the said light diffusion sheet. The surface light source device comprising a reflector and the optical sheet laminate according to claim 6 disposed so that light emitted from the light diffusion sheet is incident from the coating layer achieves the above object. To do.
[0033]
Further, the present invention, as in claim 10, is disposed on the back surface of the planar light-transmitting display body and the light-transmitting display body, and the light-transmitting display body is irradiated from the back surface from the emitted light. The above object is achieved by a transmissive display body comprising the surface light source device according to claim 7, 8 or 9.
[0034]
According to the present invention, spherical beads are included in the back surface opposite to the prism surface of the optical sheet including the prism, or the coating layer covering the back surface of the optical sheet having the light diffusion layer on the surface. And a smooth surface of the light guide plate adjacent thereto, a smooth surface of the diffusion plate, a smooth surface of another prism sheet, etc. The distance between the straight line and the reflected light is prevented from causing interference, and interference fringes or Newton rings are prevented from occurring. In addition, since the spherical beads contained in the coating layer have a half-value width of 1 μm or less in the particle size distribution, there is little variation in the amount of protrusion from the back surface of the optical sheet, and it is uniform with respect to other optical sheets such as prism sheets. Therefore, it is possible to prevent the prisms and the like of other optical sheets from being damaged by the concentrated load generated by the spherical beads protruding greatly.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0036]
As shown in FIGS. 1 and 2, the optical sheet 10 according to the present invention includes a triangular prism unit prism 14 on one surface (upper surface in FIGS. 1 and 2) of a transparent base sheet 12 and a ridge line 14 </ b> A. Are arranged in parallel in a one-dimensional direction so as to be parallel to each other to form a prism surface 16, and a coating layer 18 is provided on the back side opposite to the prism surface 16. Includes spherical beads having a particle size of 1 to 10 μm and a half-value width of particle size distribution of 1 μm or less.
[0037]
On the surface of the coating layer 18, the spherical beads 20 are arranged in a random two-dimensional distribution state.
[0038]
The optical sheet 10 is disposed with its coating layer 18 side in contact with a smooth surface 22A of another light transmissive material 22, such as a smooth surface of a light guide plate, a smooth surface of a diffusion sheet, or a smooth surface of another prism sheet. Then, conventionally, as described above, interference fringes are generated by the surface light source light from the direction of the light guide plate or the like. However, in the optical sheet 10 of the present invention, as shown in FIG. Since the spherical beads 20 projecting from the surface of the spherical beads 20 are in contact with the smooth surface 22A of the light-transmitting material 22 such as a light guide, the gap between the smooth surface 22A and the surface of the coating layer 18 is always about 1 to 10 μm. The gap 24 is generated.
[0039]
For this reason, even if light enters from the opposite side (lower side in FIG. 2) of the smooth surface 22A of the translucent material 22, interference fringes do not occur in combination with the light diffusing action of the spherical beads.
[0040]
Further, as described above, since the spherical beads 20 have a half-value width of 1 μm or less in the particle size distribution, the variation in the protruding height of the spherical beads 20 from the surface of the coating layer 18 is 1 μm or less. Therefore, even if the spherical beads 20 come into contact with the tip of the prism portion of another prism sheet or the smooth surface of another translucent material, the contact state is uniform. No concentrated load is generated, and damage to the prism portion of the prism sheet is prevented.
[0041]
Here, the protruding height of the spherical beads 20 from the surface of the coating layer 18 is set to 1 μm or more. If the height is less than 1 μm, the distance of the gap 24 is the wavelength of the surface light source light (visible light). If it is less than 1 μm, it is difficult to mass-produce translucent beads (for example, acrylic beads) as the material of the spherical beads 20, and the spherical beads are coated. This is to avoid the problem that it is difficult to disperse in the binder (described later) constituting the layer 18. Furthermore, this is also to avoid the problem that light from the translucent material directly enters the coating layer 18 as an evanescent wave and cannot maintain a uniform luminance in the plane.
[0042]
The spherical beads 20 have a particle size of 10 μm or less. When the gap 24 is larger than 10 μm, the light from the surface light source is condensed in a specific direction, for example, the normal direction of the light exit surface on the prism surface 16 side. This is in order to avoid a significant decrease in the function to be performed.
[0043]
When the spherical beads 20 are provided on the coating layer 18, the light-transmitting beads constituting the spherical beads 20 are mixed with a binder and applied to the back surface of the optical sheet 10 (see later). In this case, Although the protrusion height of the spherical beads 20 varies, this protrusion height refers to the 10-point average roughness Rz according to JISB0601.
[0044]
As described above, the spherical beads 20 are randomly distributed two-dimensionally on the surface of the coating layer 18 and are not periodically arranged.
[0045]
If the spherical beads 20 are periodically arranged in the coating layer 18 and the period overlaps with the arrangement period of the unit prisms 14, moiré fringes are generated.
[0046]
For example, when the optical sheet as described above is provided on the light exit surface side of the backlight of a color liquid crystal display device, if the spherical beads 20 are periodically arranged, similarly, the arrangement of pixels of the liquid crystal display device Moire fringes may occur due to overlapping with the period.
[0047]
In the optical sheet 10 according to the present invention, since the spherical beads 20 are randomly arranged two-dimensionally, the occurrence of moire fringes as described above is prevented.
[0048]
Transparent materials for forming the transparent base sheet 12, the unit prism 14, and the spherical beads 20 constituting the optical sheet 10 include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, acrylic resins such as polymethyl methacrylate, and polycarbonate resins. , Ionizing radiation curable resins made of thermoplastic resins such as polystyrene resin and polymethylpentene resin, oligomers such as polyester acrylate, urethane acrylate, epoxy acrylate and / or acrylate monomers, and electromagnetic radiation such as ultraviolet rays and electron beams A resin having good transparency, such as a resin cured in (1), is used. In the case of such a resin, those having a refractive index of about 1.4 to 1.6 are usually used. In addition, other than resin, glass, ceramics, etc. may be used as long as it is transparent.
[0049]
The coating layer 18 including the spherical beads 20 as described above is formed by applying a paint in which the spherical beads 20 are dispersed in a translucent binder by spray coating, roll coating, or the like to form the coating layer 18. Part or all of the spherical beads 20 are protruded from the coating surface of the coating layer 18.
[0050]
In this case, the coating layer 18 formed by applying a coating material in which the spherical beads 20 are dispersed in the light-transmitting binder is submerged in the light-transmitting binder as shown in FIG. However, part of the spherical beads 20 protrudes from the surface of the coating layer 18 by drying and shrinking the coating film.
[0051]
Here, as the material of the spherical beads 20, polymethyl methacrylate (acrylic) beads having a diameter of 1 to 10 μm, polybutyl methacrylate beads, polycarbonate beads, polyurethane beads, calcium carbonate beads, silica beads, etc. Is used. Further, the diameter of the spherical beads 20 means an average value of diameters of particles of 1 μm or more.
[0052]
As the binder resin for forming the coating layer 18, a transparent material such as acrylic, polystyrene, polyester, vinyl polymer or the like is used, but the refractive index of the material for forming the spherical beads 20 and the refractive index of the binder resin are used. The ratio is preferably in the range of 0.9 to 1.1, and the concentration of the light-transmitting fine particles is preferably 2 to 15% of the binder resin.
[0053]
In the range of the refractive index ratio of 0.9 to 1.1, when the refractive index ratio is out of the above range, the surface light source light incident from the surface of the coating layer 18 is directed in a specific direction, for example, the normal line of the light exit surface. It is determined from the fact that the original action of the optical sheet having a prism surface, which condenses light in the direction to improve luminance, is significantly reduced.
[0054]
Furthermore, the thickness of the coating layer 18 is preferably in the range of 1 to 20 μm, excluding the protruding height of the spherical beads 20.
[0055]
This is because when the thickness of the coating layer 18 is less than 1 μm, it becomes impossible to fix the spherical beads 20 to the back surface of the transparent substrate sheet 12, and when the thickness is 20 μm or more, the light transmittance decreases, as described above. This is because the original luminance improving action of the optical sheet having the prism surface is significantly reduced.
[0056]
As a method for manufacturing the optical sheet 10, an optical sheet having a single layer structure (intermediate sheet before coating) may be a thermoplastic resin hot press method disclosed in, for example, Japanese Patent Laid-Open No. 56-157310, or injection. It can be produced by a molding method, cast molding of a curable resin by ultraviolet rays or heat, and the like.
[0057]
Further, as another method for manufacturing the intermediate sheet as described above, for example, as disclosed in Japanese Patent Laid-Open No. 5-1699015, a concave portion having a shape opposite to the shape of a desired lens arrangement (exactly uneven Filling the roll intaglio with a shape) with an ionizing radiation curable resin liquid, overlaying the translucent substrate sheet 12 on this, and irradiating ionizing radiation such as ultraviolet rays and electron beams from the transparent substrate sheet side as it is, By curing the ionizing radiation curable resin liquid and then peeling the transparent base sheet together with the cured resin from the roll intaglio, the cured ionizing radiation curable resin liquid becomes a lens array of a desired shape and becomes a transparent base. Some form on the material sheet. The total thickness of the optical sheet 10 is usually about 20 to 1000 μm.
[0058]
In the optical sheet 10, the prism surface 16 is configured by arranging a plurality of triangular prism unit prisms 14 in parallel. However, the present invention is not limited to this, and FIG. The optical sheet 10A provided with the semi-cylindrical unit prism 15A shown in FIG. 4, the cross section shown in FIG. 4B is the optical sheet 10B provided with the sine curve unit prism 15B, and the cross section shown in FIG. In FIG. 5A, the optical sheet 10E is provided with a unit prism 15E having a sine curve in the upper half (mountain) and a V-shaped unit prism in the lower half (valley), and a unit prism having a trapezoidal cross section shown in FIG. As in the optical sheet 10 </ b> C provided with 15 </ b> C, columnar unit prisms may be arranged adjacent to each other so that the axis thereof is parallel to the one-dimensional direction.
[0059]
Further, the cross section of the unit prism is not limited to a semicircular shape or a sine curve shape, and may be a polygon other than a caroid, a Rankine egg, a cycloid, a limboline, or a triangle.
[0060]
Further, as shown in FIG. 5B, for example, an optical sheet 10D having a so-called fly-eye lens or the like in which unit prisms 15D each having a hemispherical shape independently protruded are arranged in a two-dimensional direction. Also good. The unit prism may be pyramidal.
[0061]
Further, the optical sheet of the present invention may be used as a laminated body in which a plurality of sheets are stacked as shown in FIG.
[0062]
The optical sheet laminate 26 in FIG. 6 is obtained by laminating two optical sheets 10, the coating layer 18 in the upper optical sheet 10 is the lower surface, and the prism surface 16 that is the upper surface in the lower optical sheet 10. It is arranged to touch. That is, the ridge line 14 </ b> A of the unit prism 14 in the lower optical sheet 10 is in contact with the upper coating layer 18.
[0063]
The upper and lower optical sheets 10 are arranged so that the ridge lines 14A of the unit prisms 14 are orthogonal to each other in plan view.
[0064]
The laminated body 28 in FIG. 7 is configured such that the front and back surfaces of the two optical sheets 10 are reversed from those in FIG. 6 so that the prism surfaces 16 are both on the light receiving side.
[0065]
Hereinafter, a second example of the embodiment of the present invention will be described in detail with reference to the drawings. In the second example, the same parts as those in the optical sheet of FIGS.
[0066]
As shown in FIGS. 8 and 9, the optical sheet 70 according to the second example of the embodiment of the present invention has a light diffusion layer on one surface (the upper surface in FIGS. 8 and 9) of the transparent substrate sheet 12. 72, a coating layer 18 is provided on the back side opposite to the light diffusion layer 72. Further, the coating layer 18 has a particle diameter of 1 to 10 μm made of a translucent material, Spherical beads having a half-value distribution of 1 μm or less are included.
[0067]
On the surface of the coating layer 18, the spherical beads 20 are arranged in a random two-dimensional distribution state.
[0068]
When the optical sheet 70 is disposed on the coating layer 18 side in contact with another light-transmitting material, for example, the prism surface of a prism sheet 76 having triangular prism-shaped unit prisms 74 as shown in FIG. Conventionally, as described above, the prism (or lens) portion in contact with the light diffusing sheet is scratched by unevenness on the surface of the light diffusing sheet. However, since the spherical beads 20 have a half-value width of 1 μm or less as described above, the spherical beads 20 can be removed from the surface of the coating layer 18. The protrusion height variation is 1 μm or less. Therefore, even if the spherical beads 20 come into contact with the tip of the prism portion of another prism sheet or the smooth surface of another translucent material, the contact state is uniform. No concentrated load is generated, and damage to the prism portion of the prism sheet is prevented.
[0069]
The light diffusion layer 72 in the optical sheet 70 only needs to have a function of diffusing light, and is composed of a coating layer made of a translucent material, for example, containing translucent spherical beads having a particle diameter of 1 to 30 μm. .
[0070]
In this case, in order to further increase the brightness enhancement effect in the normal direction of the sheet as the light diffusion sheet, the average particle diameter of the light transmitting spherical beads in the light diffusion layer 72 is set so that the light transmission in the coating layer 18 It is necessary to make it larger than the average particle diameter of the spherical beads 20.
[0071]
Here, the full width at half maximum of the particle size distribution of the light-transmitting spherical beads in the light diffusion layer 72 is not particularly limited, but when other optical materials in contact with the light diffusion layer 72 are easily damaged, Like the half width of the particle size distribution of the translucent spherical beads 20 in the coating layer 18, it is preferably 1 μm or less.
[0072]
Since the materials, characteristics, and the like of the transparent base sheet 12, the coating layer 18, and the spherical beads 20 are the same as those in the first example of the embodiment, description thereof is omitted.
[0073]
The optical sheet 70 is laminated with a prism sheet 76 having triangular prism-shaped unit prisms 74 as shown in FIG. 10, but the present invention is not limited to this, and other shapes are possible. For example, a prism sheet having unit prisms as shown in FIGS. 4 to 5 may be used.
[0074]
Further, as shown in FIGS. 6 and 7, the prism sheet may be a laminated body in which a plurality of prism sheets are stacked to enhance the directivity of emitted light. In this case, in the upper and lower prism sheets, the ridgelines of the unit prisms are preferably arranged so as to be orthogonal in a plan view.
[0075]
The optical sheet 70 is naturally applicable not only when it is used by being laminated on a prism sheet, but also when it is used by being laminated with another optical material whose surface is easily damaged.
[0076]
Next, a surface light source device 30 according to an example of an embodiment of the present invention will be described with reference to FIG.
[0077]
This surface light source device 30 is provided with the optical sheet 10 shown in FIG. 1 on the light emission surface side, and is a plate-like body made of a translucent material, and from the left side end surface 32A in FIG. The introduced light is disposed along and parallel to the light guide 32 configured to emit light from the upper light emitting surface 32B, and the side end surface 32A of the light guide 32, and the side end surface 32A. A linear light source 34 for allowing light to enter the light guide 32, a surface of the light guide 32 opposite to the light emission surface 32B, and a side end surface other than the left side end surface 32A. And a light reflecting plate 36 for reflecting the light emitted from these surfaces and returning it into the light guide 32.
[0078]
The coating layer 18 of the optical sheet 10 is disposed in contact with the light emitting surface 32 </ b> B of the light guide 32. In general, the light guide 32 is housed in a housing (not shown) having the light emitting surface 32B as a window.
[0079]
The light guide 32 is selected from the same translucent material as the material of the optical sheet 10 as its material, but usually acrylic or polycarbonate resin is used. Further, the thickness of the light guide 32 is usually about 1 to 10 mm, and is the thickest at the position of the side end surface 32A on the linear light source 34 side, and has a tapered shape that gradually decreases in the opposite direction. .
[0080]
In order to emit light from a wide surface (light emission surface 32B), the light guide 32 has a light scattering function added to the inside or the surface thereof. The linear light source 34 is preferably a fluorescent lamp in order to obtain uniform brightness on the light emission surface 32B.
[0081]
Further, in the surface light source device 30, the light source for entering the light into the light guide 32 is not limited to a linear light source, but a point light source such as an incandescent light bulb or LED (light emitting diode) is formed in a line shape. You may arrange. A plurality of small flat fluorescent lamps may be arranged along the side end face 32A.
[0082]
In the surface light source device 30 shown in FIG. 11, since the optical sheet 10 contacts the light emitting surface 32B of the light guide 32 via the spherical beads 20 protruding from the coating layer 18, as described above, the coating layer Interference fringes are prevented from occurring at a position between the 18 surface and the light emitting surface 32B. Therefore, a good light emitting surface can be formed as a surface light source for a transmissive liquid crystal display device or the like. In addition, the spherical beads 20 rarely damage the light emitting surface 32B of the light guide 32.
[0083]
For example, the light guide 32 may be formed in a plate shape having a uniform thickness, and a linear light source may be provided on the side end surface opposite to the side end surface 32A to guide light from here. In this way, the prism surface 16 can have higher luminance, and the uniformity of the luminance distribution on the prism surface 16 can be improved.
[0084]
Next, the direct type surface light source device 40 will be described with reference to FIG.
[0085]
In the surface light source device 40, a light diffusion sheet 42 is disposed along the coating layer 18 on the back surface side of the optical sheet 10 shown in FIG. 1, and light from the light source 34 is transmitted to the light reflecting plate 44 on the concave surface. And light is directly emitted from the light diffusion sheet 42 to the optical sheet 10.
[0086]
Also in this surface light source device 40, the distance between the surface of the coating layer 18 of the optical sheet 10 and the light diffusion sheet 42 is 1 to 4 by the spherical beads 20, as in the above-described surface light source device 30. 10 Since it is regulated to μm, no interference fringes occur between the two. Further, the spherical beads 20 are very unlikely to damage the light diffusion sheet 42.
[0087]
As the light reflecting plates 36 and 44, a thin metal plate deposited with aluminum or the like, or white foamed PET (polyethylene terephthalate) is used.
[0088]
In addition, the shape of the light reflection plate 44 in the direct type surface light source device 40 may be any shape as long as the light from the linear light source 34 can be reflected uniformly as a parallel light beam. A shape such as a columnar shape or an elliptical columnar shape is selected.
[0089]
In the surface light source device 30, the coating layer 18 of the optical sheet 10 is directly disposed on the light emitting surface 32B of the light guide 32. However, the present invention is not limited to this, and for example, shown in FIG. As in the surface light source device 30A, the light diffusion sheet 46 may be disposed between the optical sheet 10 and the light emission surface 32B.
[0090]
Further, in each of the optical sheets 10, the coating layer 18 is arranged toward the light incident side. This is because, for example, the surface light source devices 30B and 40A shown in FIGS. The 14 side may be arranged toward the light emitting surface 32B of the light guide 32 or the light reflecting plate 44 side.
[0091]
Further, each of the surface light source devices 30, 30A, 30B, 40, and 40A uses one optical sheet 10, but the present invention is not limited to this, and FIGS. As shown, two or three or more optical sheets may be used in an overlapping manner. In this way, even when a plurality of optical sheets are used in an overlapping manner, as described above, the variation in the protruding height of the spherical beads 20 from the rear surface of the optical sheet is small. Will not be damaged.
[0092]
A surface light source device 50A in FIG. 16 is obtained by disposing the second optical sheet 52 between the light emitting surface 32B of the light guide 32 and the optical sheet 10 in the surface light source device 30 shown in FIG. It is.
[0093]
The second optical sheet 52 basically has the same configuration as that of the optical sheet 10, but has no spherical beads on the coating layer side and has a smooth surface similar to the conventional one.
[0094]
Further, the ridge line 54 </ b> A of the unit prism 54 in the second optical sheet 52 is arranged in a direction orthogonal to the ridge line 14 </ b> A of the unit prism 14 in the optical sheet 10.
[0095]
In the case of this surface light source device 50A, an interference fringe is generated between the light emitting surface 32B of the light guide 32 at a smooth surface position opposite to the prism surface of the second optical sheet 52. By covering the upper side with the optical sheet 10, interference fringes could not be observed from the outside.
[0096]
A surface light source device 50B shown in FIG. 17 is a direct type of the configuration shown in FIG. 16, and the same parts as those in FIGS.
[0097]
Further, in the surface light source devices 50A and 50B in which two prism sheets as described above are stacked, the second prism sheet 52 is disposed with the unit prism 54 facing the light exit surface side. However, the unit prism 54 of the second optical sheet 52 is arranged on the light guide 32 or the light diffusion sheet 46 side as in, for example, the surface light source devices 50C and 50D shown in FIGS. You may make it arrange | position toward.
[0098]
In FIG. 18 and FIG. 19, the same parts as those in FIG. 16 and FIG.
[0099]
Next, a liquid crystal display device 60 according to an example of the embodiment of the present invention shown in FIG. 20 will be described.
[0100]
In the liquid crystal display device 60, a liquid crystal panel 62 is disposed on the light exit surface side of the surface light source device 50 as shown in FIG. 11, FIG. 13, FIG. 14, FIG.
[0101]
This liquid crystal display device is a transmissive type, and each pixel forming a liquid crystal screen is illuminated from the back side by light emitted from the surface light source device 50.
[0102]
In the liquid crystal display device 60, as described above, since there is no interference fringe in the illumination light from the surface light source device 50, a good image can be formed. Further, the distance between the surface of the coating layer 18 of the optical sheet 10 and the smooth surface of the light guide 32, the light diffusing sheet, and the other optical sheet opposed thereto is as described above. 10 Since it is μm or less, the light collecting performance of the optical sheet 10 in the normal direction, for example, is not deteriorated, and good luminance can be obtained.
[0103]
Next, a surface light source device 80 according to an example of an embodiment of the present invention will be described with reference to FIG.
[0104]
In this surface light source device 80, the optical sheet 70 shown in FIG. 8 is provided on the light emission surface side with the coating layer 18 side in contact with the prism surface of the prism sheet 76. FIG. The plate-like body made of a light-transmitting material similar to that of the surface light source device 30 of FIG. 21, wherein the light introduced from the left side end surface 32A in FIG. 21 is guided from the upper light emitting surface 32B. A light source 32, a linear light source 34 that is disposed along and parallel to the side end surface 32 </ b> A of the light guide 32, and allows light to enter the light guide 32 from the side end surface 32 </ b>A; The light guide 32 is arranged so as to cover the surface opposite to the light emission surface 32B and the side end surfaces other than the left side end surface 32A, and reflects light emitted from these surfaces to make it inside the light guide 32. And a light reflecting plate 36 for returning to To have. Note that the light guide 32 is usually housed in a housing (not shown) having the light emitting surface 32B as a window.
[0105]
In the surface light source device 80, as described above, since the spherical beads 20 of the coating layer 18 have a half-value width of 1 μm or less in the particle size distribution, the spherical beads 20 protrude from the surface of the coating layer 18. The variation in height is 1 μm or less. Therefore, even when the spherical beads 20 come into contact with the prism portion tips of the prism sheet 76, the contact state is uniform, so that no concentrated load is generated due to contact with the large protruding spherical beads. Damage to the parts is prevented.
[0106]
In FIG. 21, the light guide is similarly applied when the prism sheet 76 is not present, that is, when the coating layer 18 of the optical sheet 70 is disposed in contact with the light emitting surface 32 </ b> B of the light guide 32. Damage to the body 32 is prevented.
[0107]
The material, shape, light scattering function, and light source of the light guide 32 are the same as those in FIG.
[0108]
Next, the direct type surface light source device 82 will be described with reference to FIG.
[0109]
In this surface light source device 82, a prism sheet 76 is disposed along the coating layer 18 on the back surface side of the optical sheet 70 shown in FIG. 8, and light from the light source 34 is transmitted by the light reflecting plate 44 on the concave surface. The light is reflected and directly emitted from the other light diffusion sheet 42 to the prism sheet 76.
[0110]
Also in the surface light source device 82, the prism surface is very rarely damaged by the spherical beads 20 of the coating layer 18 of the optical sheet 70.
[0111]
In addition, the prism sheet 76 is arranged with the prism surface facing the light emitting side. This is because the unit prism 74 is a surface light source device 80A, 82A shown in FIGS. 23 and 24, for example. You may make it arrange | position toward the light emission surface 32B of the light guide 32, or the light reflection board 44 side.
[0112]
Further, each of the surface light source devices 80, 80A, 82, 82A uses a single prism sheet, but the present invention is not limited to this, as shown in FIGS. In addition, two or three or more prism sheets may be used in an overlapping manner. In this way, even when a plurality of prism sheets are used in an overlapping manner, as described above, the variation in the protruding height of the spherical beads 20 from the back surface of the prism sheet is small. Will not be damaged.
[0113]
A surface light source device 84A in FIG. 25 is obtained by disposing the second optical sheet 86 between the light emitting surface 32B of the light guide 32 and the optical sheet 70 in the surface light source device 80 shown in FIG. It is.
[0114]
The second optical sheet 86 has basically the same configuration as the optical sheet 70, but may have various unit prisms as shown in FIGS.
[0115]
Further, the ridge line 88A of the unit prism 88 in the second optical sheet 86 is arranged in a direction orthogonal to the ridge line 74A of the unit prism 74 in the optical sheet 70.
[0116]
The surface light source device 84B shown in FIG. 26 is a direct type of the configuration of FIG. 25, and the same parts as those in FIGS. .
[0117]
Further, in the surface light source devices 84A and 84B in which two optical sheets as described above are stacked, the second optical sheet 86 is disposed with the unit prism 88 facing the light exit surface side. However, the unit prism 88 of the second optical sheet 86 is arranged on the light guide 32 or the light diffusion sheet side as in the surface light source devices 84C and 84D shown in FIGS. 27 and 28, for example. You may make it arrange | position toward.
[0118]
27 and 28, the same parts as those in FIGS. 25 and 26 are denoted by the same reference numerals, and the description thereof will be omitted.
[0119]
Next, a liquid crystal display device 90 according to an example of the embodiment of the present invention shown in FIG. 29 will be described.
[0120]
In this liquid crystal display device 90, a liquid crystal panel 92 is disposed on the light exit surface side of the surface light source device 84 as shown in FIG. 21, FIG. 23, FIG. 25 or FIG.
[0121]
This liquid crystal display device is a transmissive type, and each pixel forming the liquid crystal screen is illuminated from the back side by the light emitted from the surface light source device 84.
[0122]
In the liquid crystal display device 90, as described above, since there is no interference fringe in the illumination light from the surface light source device 84, a good image can be formed.
[0123]
【Example】
Next, examples of the present invention will be described.
[0124]
The optical sheet 10 is formed by applying a prepolymer of epoxy acrylate to form a unit prism pattern on a transparent biaxially stretched PET film (film thickness 125 μm) by applying a transparent adhesive layer to about 1 μm. By applying an ultraviolet curable resin as a main component and releasing the mold after curing (solidifying) the resin coating film, the unit prism shape cross section is an isosceles triangle having an apex angle of 85 ° and a ridge line 14A. Are arranged adjacent to each other so that they are parallel to each other. The spherical beads 20 were disposed on the side surface (back surface) opposite to the prism surface 16 of the transparent base sheet 12 on which the unit prisms 14 were formed in the following manner.
[0125]
The light-transmitting beads as the material of the spherical beads 20 are coated with a coating made of a cross-linked acrylic resin (n = 1.49) having an average particle diameter of 5 μm and a polyester resin (n = 1.55) as a binder.
[0126]
Specifically, an ink containing 8% of the binder resin in the translucent beads was diluted with a solvent of MET: toluene = 1: 1, and the viscosity was set to 27 seconds with a Zaan cup viscometer # 3. .
[0127]
This ink was applied to the back surface of the transparent substrate sheet 12 on which the unit prisms 14 were formed by the slit reverse coating method, and then the solvent was dried to solidify the coating film.
[0128]
In this dried coating film, spherical beads 20 having a 10-point average roughness Rz = 3 μm according to JISB0601 were formed in a two-dimensional random array with an average interval d = 30 μm.
[0129]
When the optical sheet 10 thus formed was observed in a dark room, for example, in contact with the light emitting surface of the light guide 32, no interference fringes were observed.
[0130]
The average particle diameter of the translucent beads is variously changed to form an optical sheet 10 similar to the above, and this is incorporated into a surface light source device as shown in FIGS. 11 to 19 and observed in a dark room. The result is as shown in Table 1 below.
[0131]
[Table 1]
[0132]
As a result, interference fringes were observed only in Comparative Examples 1 and 2 in Table 1.
[0133]
Further, when one optical sheet of Example 1 in Table 1 and an optical sheet with an isosceles triangular columnar prism with an apex angle of 90 ° and a smooth back surface were assembled as shown in FIG. The result was as follows.
[0134]
[Table 2]
[0135]
Further, as shown in FIG. 30, an optical sheet coated with the spherical beads 20 having a particle size distribution of the present invention and an optical sheet coated with the spherical beads 20A having a large variation in the particle size distribution are used. As a result of an experiment in which the side was brought into contact with, for example, a prism surface and dragged with a 10 g cylinder, the larger the variation in particle size distribution, the more scratches were generated. In particular, when the half width of the particle size distribution was 1 μm or less, the scratches on the prism surface were very small.
[0136]
The light diffusing layer 72 of the optical sheet 70 which is a light diffusing sheet is composed of a transparent bead as a spherical bead material, a cross-linked acrylic resin (n = 1.49) having an average particle diameter of 5 μm, and a polyester resin (n = 1.55).
[0137]
The coating layer 18 containing the spherical beads 20 was disposed on the side surface (rear surface) opposite to the light diffusion layer 72 of the transparent base sheet 12 in the following manner as in the above-described example.
[0138]
When the optical sheet 70 thus formed was observed in a dark room, for example, in contact with the light emitting surface of the light guide 32, no interference fringes were observed.
[0139]
The prism sheet 76 is formed by coating a transparent biaxially stretched PET film (film thickness 125 μm) with a transparent adhesive layer so as to have a thickness of about 1 μm, and an epoxy acrylate prepolymer that forms a unit prism pattern thereon. By applying an ultraviolet curable resin as a main component and releasing the mold after curing (solidifying) the resin coating film, the unit prism shape cross section is an isosceles triangle having an apex angle of 85 ° and a ridge line 14A. Are arranged adjacent to each other so that they are parallel to each other.
[0140]
Variously changing the average particle diameter of the translucent beads to form an optical sheet which is a light diffusion sheet similar to the above, and incorporating this into a surface light source device as shown in FIGS. When observed in a dark room, the same results as in Table 1 were obtained.
[0141]
Further, as shown in FIG. 21, one optical sheet, which is a light diffusion sheet corresponding to Example 1 in Table 1, and a prism sheet of an isosceles triangular columnar prism having a vertex angle of 90 ° on the surface side are incorporated. However, defects such as scratches on the optical sheet were concealed, and the light output distribution became smoother.
[0142]
Further, as shown in FIG. 30, an optical sheet which is a light diffusion sheet coated with spherical beads 20 having a particle size distribution according to the present invention, and an optical sheet coated with spherical beads 20A having a large variation in particle size distribution. In the experimental results in which the spherical bead 20 side was brought into contact with, for example, the prism surface and dragged with a 10 g cylinder, the larger the variation in particle size distribution, the more flaws were generated. In particular, when the half width of the particle size distribution was 1 μm or less, the scratches on the prism surface were very small. In particular, when the prism apex angle of the optical sheet is sharp at 100 ° or less, the influence due to the above-described variation in the particle size of the beads was large.
[0143]
【The invention's effect】
Since the present invention is configured as described above, it is possible to eliminate interference fringes that do not depend on external light generated in the optical sheet, and in the surface light source device and transmissive display body using the optical sheet, interference fringes can be obtained. A high-quality image can be obtained in which the optical sheet is not observed, and the optical sheet has an excellent effect of significantly reducing the scratches on the contacting optical member.
[Brief description of the drawings]
FIG. 1 is an enlarged perspective view showing a part of an optical sheet having a prism surface according to an example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a part of the optical sheet further enlarged.
FIG. 3 is a cross-sectional view showing a coating layer forming process in the optical sheet.
4 is a perspective view showing a second example and a third example of an embodiment of an optical sheet. FIG.
FIG. 5 is a perspective view showing a fourth example and a fifth example of the embodiment;
FIG. 6 is a perspective view showing a first example of an embodiment of an optical sheet laminate.
FIG. 7 is a perspective view showing a second example of the embodiment;
FIG. 8 is an enlarged cross-sectional view showing a part of an optical sheet as a light diffusion sheet according to an example of an embodiment of the present invention.
FIG. 9 is a sectional view showing a coating layer forming process in the optical sheet.
FIG. 10 is a perspective view showing a first example of an embodiment of an optical sheet laminate using the optical sheet.
FIG. 11 is a perspective view showing a main part of a surface light source device using an optical sheet having a prism surface according to an example of an embodiment of the present invention.
FIG. 12 is a perspective view showing a second example of the embodiment of the surface light source device.
FIG. 13 is a schematic cross-sectional view showing a third example of the embodiment of the same surface light source device.
FIG. 14 is a schematic sectional view showing a fourth example of the embodiment;
FIG. 15 is a schematic sectional view showing a fifth example of the embodiment;
FIG. 16 is a perspective view showing the main part of a sixth example of the embodiment;
FIG. 17 is a perspective view showing the main part of a seventh example of the embodiment;
FIG. 18 is a perspective view showing a main part of an eighth example of the embodiment.
FIG. 19 is a perspective view showing a main part of a ninth example of the embodiment.
FIG. 20 is a schematic side view showing a liquid crystal display device according to an example of an embodiment of the present invention.
FIG. 21 is a perspective view showing a main part of a surface light source device according to an example of an embodiment using an optical sheet which is a light diffusion sheet of the present invention.
FIG. 22 is a perspective view showing a second example of the embodiment of the surface light source device.
FIG. 23 is a schematic sectional view showing a third example of the embodiment of the same surface light source device.
FIG. 24 is a schematic sectional view showing a fourth example of the embodiment;
25 is a perspective view showing the main part of a fifth example of the embodiment; FIG.
FIG. 26 is a perspective view showing the main part of a sixth example of the embodiment;
FIG. 27 is a perspective view showing the main part of a seventh example of the embodiment;
28 is a perspective view showing the main part of an eighth example of the embodiment. FIG.
FIG. 29 is a schematic side view showing a liquid crystal display device according to an example of an embodiment of the present invention.
FIG. 30 is an enlarged cross-sectional view showing a comparison between an optical sheet coated with the spherical beads of the present invention and an optical sheet coated with spherical beads having a large variation in particle size distribution.
[Explanation of symbols]
10, 10A, 10B, 10C, 10D, 70 ... Optical sheet
12 ... Transparent base sheet
14, 15A, 15B, 15C, 15D ... Unit prism
14A, 54A, 74A ... Aya Line
16 ... Prism surface
18 ... coating layer
20 ... spherical beads
22 ... Translucent material
22A ... Smooth surface
24 ... Gap
26, 28 ... Optical sheet laminate
30, 30A, 30B, 40, 40A,
50, 50A, 50B, 50C, 50D, 80, 80A, 82,
82A, 84A, 84B, 84C ... surface light source device
32. Light guide
32A ... Side end face
32B ... light emission surface
34 ... Linear light source
36, 44 ... Light reflector
42, 46 ... Light diffusion sheet
52. Second optical sheet
54, 74 ... Unit prism
60, 90 ... Liquid crystal display device
72. Light diffusion layer
76 ... Prism sheet
86: Second optical sheet

Claims (10)

  1. In an optical sheet in which a plurality of unit prisms or unit lenses are arranged on the surface of a translucent substrate and the back surface is covered with a coating layer made of a translucent material, the coating layer has a half-value width of particle size distribution of 1 μm or less. An optical sheet comprising spherical beads.
  2. In an optical sheet having a light diffusing layer on the surface of a light-transmitting substrate and having the back surface covered with a coating layer made of a light-transmitting material, the coating layer is made of spherical beads having a half-value width of 1 μm or less. An optical sheet characterized by comprising.
  3. 3. The light diffusing layer according to claim 2, wherein the light diffusing layer includes a light transmitting spherical bead, and the average particle diameter of the light transmitting spherical bead in the light diffusing layer is defined as the average particle diameter of the spherical bead included in the coating layer. An optical sheet characterized by being larger than the above.
  4. 4. The optical sheet according to claim 1, wherein the spherical beads contained in the coating layer are composed of translucent beads having a particle diameter of 1 to 10 [mu] m.
  5. A plurality of optical sheets including the unit prism or unit lens according to claim 1 or 4 are laminated, and the coating layer in the laminated optical sheet is in contact with the unit prism or unit lens in the optical sheet laminated adjacently. An optical sheet laminate characterized by comprising:
  6. An optical sheet comprising the light diffusing layer according to any one of claims 2 to 4 and a plurality of prism sheets each having a plurality of unit prisms or unit lenses arranged on the surface of the light-transmitting substrate. The optical sheet laminate, wherein the coating layer is in contact with a unit prism or a unit lens in a prism sheet laminated adjacently.
  7. A light guide made of a light-transmitting material, the light guide being configured to emit light introduced from at least one side end face from a light emission surface which is one surface, and at least the light guide of the light guide The light source which makes light enter into the inside from one side end surface, The light emitted from the light emission surface provided in the light emission surface side in the light guide, and incident from the coating layer side A surface light source device comprising any one of the optical sheets according to claim 6.
  8. A light diffusing sheet; a light source that irradiates light to the light diffusing sheet; a reflector that is disposed on the opposite side of the light diffusing sheet from the light source and reflects light from the light source toward the light diffusing sheet; A surface light source device comprising: the optical sheet according to any one of claims 1 to 4 disposed so that light emitted from the diffusion sheet is incident from the coating layer.
  9. A light diffusing sheet; a light source that irradiates light to the light diffusing sheet; a reflector that is disposed on the opposite side of the light diffusing sheet from the light source and reflects light from the light source toward the light diffusing sheet; A surface light source device comprising: the optical sheet laminate according to claim 5 or 6 arranged so that light emitted from the diffusion sheet is incident from the coating layer.
  10. A planar light-transmitting display body, and a surface of the light-transmitting display body, which is disposed on the back surface of the light-transmitting display body, wherein the light-transmitting display body is irradiated from the back surface by emitted light. And a light source device.
JP33166697A 1997-08-26 1997-12-02 Optical sheet, optical sheet laminate, surface light source device, and transmissive display device Expired - Lifetime JP3913870B2 (en)

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JP9-229364 1997-08-26
JP22936497 1997-08-26
JP33166697A JP3913870B2 (en) 1997-08-26 1997-12-02 Optical sheet, optical sheet laminate, surface light source device, and transmissive display device

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JP33166697A JP3913870B2 (en) 1997-08-26 1997-12-02 Optical sheet, optical sheet laminate, surface light source device, and transmissive display device
US09/064,059 US5995288A (en) 1997-04-22 1998-04-22 Optical sheet optical sheet lamination light source device, and light-transmissive type display apparatus
US09/358,697 US6147804A (en) 1997-04-22 1999-07-21 Optical sheet lamination
US09/664,057 US6333817B1 (en) 1997-04-22 2000-09-18 Optical lamination sheet
US09/956,071 US6560023B2 (en) 1997-04-22 2001-09-20 Optical lamination sheet
US10/334,977 US6700707B2 (en) 1997-04-22 2003-01-02 Optical sheet lamination
US10/673,410 US6825984B2 (en) 1997-04-22 2003-09-30 Optical sheet lamination

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