JP5266082B2 - Light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate capable of guiding reflection light toward an innermost part of the room in winter time, in case of use as a light shelf. <P>SOLUTION: The light guide plate includes a prism face 3 configured such that triangular unit prisms 3a are continuously arrayed in parallel in their width direction at an underside of a transparent resin plate 2, with a top angle &alpha; of the unit prisms 3a constituting the prism face 3 of 120&deg; or more and less than 170&deg;, and with a difference in two bottom angles &beta;, &gamma;. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a light guide plate that reflects part of incident light from the upper surface side to the upper surface side and transmits the other part to the lower surface side, and in particular, can be suitably used as a material for a light shelf. About.

  In order to brighten the room using daylight, it is generally necessary to increase the opening area of the window. However, a large opening area cannot be easily obtained in terms of a decrease in the seismic strength of the building due to an increase in openings and cost. In addition, the large opening area may cause a rise in indoor temperature in summer and a decrease in heat insulation effect in winter.

Therefore, for example, as shown in FIG. 1, a cocoon (referred to as a “light shelf”) is horizontally installed at the intermediate position in the height direction of the window, and the direct sunlight is shielded from the underside window, Taking light reflected on the roof part from the upper diffusion window and reflecting it on the indoor ceiling part and introducing it into the indoor rules as indirect illumination light is being adopted, for example, around school classroom windows (see Patent Document 1). ).
By using such a light shelf, it is possible to brighten the room with soft indirect illumination light, and to reduce the cooling load due to illumination energy and solar shading.

  However, when a light shelf that reflects sunlight is installed at the intermediate position in the height direction of the window part, the sunlight is blocked by the light shelf, so this part becomes darker on the contrary and the balance of daylighting deteriorates. was there.

  In view of this, it has been proposed to control the amount of sunlight incident on and reflected from the building by attaching a prism face material to the light shelf to control the amount of light heat in the building (Patent Document 2).

JP 2001-3661 A JP 2005-23592 A

However, when a prism surface is provided on the upper surface of the light shelf as in Patent Document 2, dust and raindrops scattered in the atmosphere adhere to the valley portion of the prism surface, so a layer for protecting the prism surface is laminated. There is a need to increase the cost and weight.
Therefore, it is conceivable to provide a prism surface on the lower surface of the light shelf. However, if the prism surface is provided on the lower surface of the light shelf, the reflection angle tends to increase. There was a problem that it was difficult to make the whole bright and warm.

  The present invention is to provide a light guide plate having a prism surface on the lower surface, which can guide reflected light to the interior of a room particularly in winter when used as a light shelf.

  In view of this problem, the present invention includes a prism surface having a configuration in which triangular unit prisms are continuously arranged in the width direction on the lower surface side of a transparent resin plate, and constitutes the prism surface. The light guide plate is characterized in that the top angle of the unit prism is not less than 120 ° and less than 170 °, and there is a difference between the two bottom angles.

With a light guide plate having such a configuration, it is possible not only to reflect more incident light rays from a low angle as in winter, but also to provide a difference between the bottom angles β and γ on both sides of the unit prism 3a. Thereby, the reflection angle of reflected light can be adjusted. Therefore, for example, it is used as a light shelf, that is, the prism surface is positioned on the side opposite to the light incident side, the length direction of the unit prism is parallel to the housing, and the two bottom angles β and γ in the unit prism 3a By using the smaller one of them on the side of the chassis, it is possible not only to increase the amount of reflected light, particularly in winter, but also to guide the reflected light further into the interior. It is possible to increase the illuminance of the whole room by taking in light.
As described above, the light guide plate of the present invention is particularly suitable as a light shelf, but can also be suitably used as a roof material such as a fence or other daylighting materials.

It is sectional drawing which showed an example of the installation state and function of the conventional light shelf. It is the longitudinal cross-sectional view which showed an example of the light-guide plate of this invention. It is the expanded sectional view which showed an example of the unit prism in the light-guide plate of this invention. It is the fragmentary sectional perspective view which showed an example of the light-guide plate of this invention. It is sectional drawing for demonstrating the example of installation of the light-guide plate which concerns on an example of this invention, and the example of a function in that case. It is a figure for demonstrating the input content of the simulation test of an Example, (A) is a cross section for demonstrating the mode and each dimension of the building installed as a light shelf, and reflection angle (theta) and reflection distance X to calculate. It is a figure, (B) is a figure for demonstrating each angle in a unit prism.

  Next, this invention is demonstrated based on embodiment. However, the embodiment described below is an example of the embodiment of the present invention, and the scope of the present invention is not limited to the following embodiment.

<Configuration of the light guide plate>
The light guide plate (referred to as “the present light guide plate”) 1 of the present embodiment includes a prism surface 3 on the lower surface side of the transparent resin plate 2 and a light beam on the upper surface side of the transparent resin plate 2 as shown in FIGS. A plate body or a sheet body provided with the absorption layer 4. However, the light absorption layer 4 is not necessarily provided.

(Transparent resin plate 2)
There are no particular restrictions on the material of the transparent resin plate 2. A transparent resin generally used as an exterior building material can be used. For example, transparent resin materials such as polycarbonate resin, polyester resin, methacrylic resin, styrene resin, polyvinyl chloride resin, polyolefin resin, and polyamide resin can be used. One or two or more of these may be mixed. Among these resins, polycarbonate resins are preferable in terms of transparency, heat resistance, impact resistance, and the like.

The polycarbonate-based resin is a linear polymer containing a carbonate ester bond in the main chain. For example, various dihydroxy diaryl compounds and phosgene are reacted by a phosgene method, or a dihydroxy diaryl compound and a carbonate ester such as diphenyl carbonate Is a polymer that can be obtained by reacting with a transesterification method. Specific examples include polycarbonate resins produced from 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), but are not limited thereto.
The molecular weight of the polycarbonate resin is not particularly limited. Those having a viscosity average molecular weight of about 15,000 to 30,000 that can be formed into a sheet by ordinary extrusion are preferred.

  Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyacrylate, polyether ether ketone, and the like.

  Examples of the methacrylic resin include polymers composed of various esters of methacrylic acid or copolymers with other monomers. For example, homopolymers of various methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and copolymers of these methacrylates with various acrylic esters, acrylic acid, styrene, α-methylstyrene, etc. Etc.

  Examples of the styrene resin include a polymer made of a styrene monomer or a copolymer using a monomer copolymerizable with the styrene monomer. Examples of the styrenic monomer include styrene, α-methylstyrene, styrene derivatives in which a hydrogen atom of a benzene nucleus is substituted with a halogen atom or an alkyl group having 1 to 2 carbon atoms, specifically, styrene, o -Chlorstyrene, p-chlorostyrene, 2,4-dimethylstyrene, t-butylstyrene and the like. Examples of the copolymerizable monomer include acrylonitrile monomers such as (meth) acrylonitrile, α-chloroacrylonitrile, vinylidene cyanide, (meth) acrylic acid, methyl (meth) acrylate, (meth) (Meth) acrylic acid such as ethyl acrylate, butyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylic acid-2-ethylhexylbutyl, (meth) acrylic acid-β-hydroxyethyl, and these Various esters or vinyl acetate, vinyl chloride, vinylidene chloride, vinyl pyrrolidone, (meth) acrylamide, maleic anhydride, itaconic anhydride, maleimide and the like can be mentioned.

  Examples of the polyvinyl chloride resin include a vinyl chloride homopolymer, a vinyl chloride copolymer obtained by copolymerizing a small amount of a comonomer, a graft copolymer, and the like. Polymer blends of these with vinylidene chloride resin, ethylene / vinyl acetate copolymer, chlorinated polyethylene and the like may be used.

  Examples of the polyolefin resin include a homopolymer of α-olefin or a copolymer of α-olefin and another copolymerizable monomer. For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, etc. It is done. Among these, low density polyethylene having a density of 0.910 to 0.935, ethylene-α-olefin copolymer, and ethylene-vinyl acetate copolymer having a vinyl acetate content of 30% by weight or less are excellent in transparency and weather resistance. ing. Among them, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 wt% to 30 wt% is particularly excellent in transparency, flexibility and weather resistance.

  Examples of the polyamide-based resin include nylon-6, nylon-66, nylon-12, nylon-46, and the like.

The transparent resin plate 2 may contain a material that absorbs near infrared rays, for example, one or more of sulfur, sulfur compounds, copper compounds, and other near infrared absorbing materials. However, it does not need to be contained.
At this time, as the sulfur, a commercially available sulfur powder or the like can be used. For example, sulfur powder made by Tsurumi Chemical Co., Ltd. (JIS grade 2 equivalent) can be used.
Examples of sulfur compounds include lead sulfide and thiourea derivatives.
Examples of the copper compound include copper stearate, copper sulfide, and phthalocyanyl copper.
Examples of other near infrared ray absorbing substances include tungsten hexachloride, tin chloride, chromium, cobalt complex salts, anthraquinone derivatives, and the like.
The content of such a near-infrared absorbing material is not particularly limited, but it is preferable to contain 0.01 to 6 parts by weight in 100 parts by weight of the transparent resin. When the content is 0.01 to 6 parts by weight, preferably 0.01 to 2 parts by weight, particularly preferably 0.01 to 1 part by weight, the light absorption performance in the near infrared region is excellent, and the visible light transmittance is high. Is expensive.

  In addition, the transparent resin plate 2 has a heat stabilizer, an ultraviolet absorber, a colorant, a fluorescent brightener, a release agent, an antiblocking agent (silica, crosslinked polystyrene beads, etc.), as long as the effects of the present invention are not impaired. You may contain additives, such as a softening material and an antistatic agent.

(Prism surface 3)
As shown in FIGS. 2 to 4, the prism surface 3 is provided on the lower surface side of the transparent resin plate 2, that is, on the side opposite to the light incident side of the light guide plate 1, and has a long triangular prism shape with a triangular cross section. The unit prisms 3a are arranged in parallel in the width direction.

The unit prism 3a preferably has a non-isosceles triangular shape in a cross section orthogonal to the length direction, and it is important that the apex angle α of the unit prism 3a is 120 ° or more and less than 170 °.
When the light guide plate 1 is installed as a light shelf so that the prism surface 3 is located on the side opposite to the light incident side and the length direction of the unit prism 3a is parallel to the housing as shown in FIG. If the apex angle α of the unit prism 3a is not less than 120 ° and less than 170 °, when the sun angle gradually decreases from the summer solstice, the amount of light reflected to the upper side of the light guide plate 1 increases, and in winter and the sun angle When it becomes the lowest (winter solstice), the amount of sunlight reflected on the upper side of the light guide plate can be sufficiently increased, and the illuminance in the room can be increased by taking light into the room. More specifically, the light angle of 20 to 40% can be reflected to the upper side of the light guide plate in the winter solstice when the angle of the sun is the lowest.
From this viewpoint, the apex angle α of the unit prism 3a is more preferably 120 to 140 °, and particularly preferably 120 to 130 °.

  As shown in FIG. 3, the top of the unit prism 3a may be rounded. From the viewpoint of the light guide property that bends the angle of the light beam incident on the light guide plate 1, it is preferable that the radius of curvature of the top is as small as possible.

It is also important that there is an angle difference between one bottom angle β and the other bottom angle γ in the unit prism 3a. By providing a difference between the bottom angles β and γ on both sides of the unit prism 3a, the reflection angle of the reflected light can be adjusted. Thus, for example, as a light shelf, the prism surface is positioned on the side opposite to the light incident side, the length direction of the unit prism is parallel to the casing, and a smaller bottom angle γ of the unit prism 3a is positioned on the casing side. By installing in such a manner, the reflected light can be guided deeper into the room, particularly in winter, and the illuminance of the entire room can be increased by taking the light deep into the room.
From this point of view, in the unit prism 3a, the indoor side bottom angle γ is preferably smaller than the outdoor side bottom angle β, and the angle difference at that time is 1 ° or more, particularly 2 ° or more, and particularly 3 ° or more. On the other hand, it is more preferably 10 ° or less, particularly 7 ° or less.

  Also, from the viewpoint that the reflected light can be guided to the interior of the room in winter, the size of the indoor side bottom angle γ of each unit prism 3a is particularly important, and is preferably 10 ° or more and less than 60 °. In particular, it is more preferably 20 to 50 °, particularly 20 to 30 °.

  Note that, between the different unit prisms 3a, the top angle α, the indoor side bottom angle γ, and the outdoor side bottom angle β may be the same or different. For example, the indoor unit bottom prism γ can be formed to have a smaller indoor side bottom angle γ.

Moreover, it is preferable that the space | interval (prism pitch) L between the adjacent unit prisms 3a and 3a is 0.5 mm-12 mm. When the prism pitch is less than 0.5 mm, as the pitch of the mold for shaping the prism increases, it becomes difficult to perform the processing because fine processing is required for manufacturing the mold. In addition, when the top is rounded, the ratio of the curved portion (R portion) increases, so that the light guide performance may be reduced. On the other hand, when the prism pitch exceeds 12 mm, the groove between the unit prisms 3a and 3a becomes deep, and the strength of the light guide plate may be reduced.
From this viewpoint, the prism pitch L is particularly preferably 1.0 mm to 10.0 mm, and more preferably 3.0 mm to 8.0 mm.

  The height H of the unit prism 3a is determined by the apex angle α of the unit prism 3a and the prism pitch L, and is preferably 0.2 mm to 3.5 mm, particularly 0.6 mm to 3.0 mm. It is preferable that it is 1.5 mm-3.0 mm especially especially.

(Light Absorbing Layer 4)
The light absorption layer 4 can be formed as an ultraviolet absorption layer, a heat ray absorption layer, or a layer including both of them.

The ultraviolet absorbing layer can be formed by mixing an ultraviolet absorbing material with a transparent resin.
At this time, as the transparent resin, the transparent resin mentioned as the material of the transparent resin plate 2 can be used. Among these, it is preferable to use the same resin as the transparent resin plate 2 in consideration of adhesiveness, light scattering at the interface, and the like.
The ultraviolet absorbing material is not particularly limited as long as it has ultraviolet absorbing performance, and for example, benzotriazole, triazine and the like can be suitably used. However, it is not limited to these.

On the other hand, the heat ray absorbing layer can be formed by mixing a transparent resin with a heat ray absorbing material, that is, a near infrared ray absorbing material or an infrared ray absorbing material.
At this time, as the transparent resin, the transparent resin mentioned as the material of the transparent resin plate 2 can be used. Among these, it is preferable to use the same resin as the transparent resin plate 2 in consideration of adhesiveness, light scattering at the interface, and the like.
The heat ray absorbing material is not particularly limited as long as it has near infrared absorbing performance or infrared absorbing performance, and includes, for example, one or more of sulfur, sulfur compounds, copper compounds and other near infrared absorbing materials. You may do.

At this time, as the sulfur, a commercially available sulfur powder or the like can be used. For example, sulfur powder made by Tsurumi Chemical Co., Ltd. (JIS grade 2 equivalent) can be used.
Examples of sulfur compounds include lead sulfide and thiourea derivatives.
Examples of the copper compound include copper stearate, copper sulfide, and phthalocyanyl copper.
Examples of other near infrared ray absorbing substances include tungsten hexachloride, tin chloride, chromium, cobalt complex salts, anthraquinone derivatives, and the like.
The content of such a near-infrared absorbing material is not particularly limited, but it is preferable to contain 0.01 to 6 parts by weight in 100 parts by weight of the transparent resin. When the content is 0.01 to 6 parts by weight, preferably 0.01 to 2 parts by weight, particularly preferably 0.01 to 1 part by weight, the light absorption performance in the near infrared region is excellent, and the visible light transmittance is high. Is expensive.

(Layer structure)
The thickness of each layer of the transparent resin plate 2 and the light absorbing layer 4 is not limited as long as there is no problem in surface hardness and moldability, and the thickness ratio is also the same. In general, the thickness (h) of the transparent resin plate 2 is 1.8 mm to 30.0 mm, particularly 2.0 mm to 15.0 mm, and particularly preferably 2.4 mm to 10.0 mm. The thickness of 4 is 10 μm to 100 μm, particularly 20 μm to 70 μm, and particularly preferably 20 μm to 40 μm.

As long as the light guide plate 1 includes the transparent resin plate 2 and the light absorption layer 4 as described above, the light guide plate 1 may include other layers.
Alternatively, a prism sheet having the prism surface 3 on one surface side of the sheet body may be formed separately from the transparent resin plate 2, and the prism sheet may be laminated on the transparent resin plate 2.

<Manufacturing method>
As a method for laminating the transparent resin plate 2 and the light absorbing layer 4, a sheet provided with the light absorbing layer 4 may be laminated on the transparent resin plate 2 formed in advance with the prism surface 3, or After the resin constituting the transparent resin plate 2 (referred to as “transparent resin plate constituting resin”) and the resin constituting the light absorbing layer 4 (referred to as “ultraviolet absorbing layer constituting resin”) are coextruded and laminated, the prism surface 3 may be shaped.

When coextruding the transparent resin plate constituent resin and the ultraviolet absorbing layer constituent resin, for example, a main extruder for extruding the transparent resin plate constituent resin and a sub-extruder for extruding the ultraviolet absorbing layer constituent resin (usually the main extruder) Preferably smaller than the machine).
At this time, if a polycarbonate resin is used as the main component resin of the transparent resin plate constituting resin and the ultraviolet absorbing layer constituting resin, the temperature condition of the main extruder is usually 250 to 290 ° C., particularly 260 to 280 ° C. The temperature condition of the sub-extruder is usually 250 to 290 ° C, particularly preferably 260 to 280 ° C.
In order to remove foreign substances in the resin, it is preferable to install a polymer filter upstream of the T-die of the extruder.

In addition, as a method of laminating two types of molten resins by coextrusion, known methods such as a feed block method and a multi-manifold method can be used.
In the case of the feed block method, the molten resin laminated in the feed block is guided to a sheet forming die such as a T die, formed into a sheet shape, and then flowed into a forming roll (polishing roll) whose surface is mirror-finished. And a mirror finish and cooling while passing through the forming roll, thereby forming a laminate.
On the other hand, in the case of the multi-manifold system, the molten resin laminated in the multi-manifold die is formed into a sheet shape inside the die in the same manner as described above, followed by surface finishing and cooling with a forming roll to form a laminated body. can do.
The temperature of the die is usually 230 to 290 ° C., preferably 250 to 280 ° C., if the polycarbonate resin is used as the main component resin of the transparent resin plate constituting resin and the ultraviolet absorbing layer constituting resin, and the molding roll temperature As, it is 100-190 degreeC normally, Preferably it is 110-180 degreeC. As the roll, a vertical roll or a horizontal roll can be appropriately used.

  As a method for shaping the prism surface 3, for example, when the transparent resin plate 2 is extruded or when a laminated sheet of the transparent resin plate 2 and the light absorbing layer 4 is co-extruded, a predetermined prism surface is used. The prism surface 3 can be shaped by pressing and cooling the metal roll engraved so that 3 can be imprinted against the extruded transparent resin plate 2.

<Application>
The light guide plate 1 is particularly suitable for use as a light shelf. In the light guide plate 1, when the prism surface is positioned on the side opposite to the light incident side and the length direction of the unit prism is arranged parallel to the housing, in summer, the temperature rise in the room is suppressed by sunlight. Conversely, in winter, the emission angle of sunlight reflected from the light guide plate can be controlled so that light can be taken into the room and the illuminance in the room can be increased. Particularly in winter, when the angle of the sun is reduced (winter solstice), as shown in FIG. 5, the amount of sunlight reflected on the upper side of the light guide plate increases, and light can be taken into the room to increase the illuminance in the room.
Further, by disposing the smaller one of the two bottom angles β and γ of the unit prism 3a on the housing side, not only the amount of reflected light can be increased, but also in the winter, Can be guided to the interior of the room, and light can be taken into the interior of the room to increase the illuminance of the entire room.
Therefore, since the light guide plate 1 can change the angle of sunlight as described above, it can be suitably used as a light shelf. However, in addition, it can be suitably used, for example, as a roofing material for roofs or other daylighting materials.

<Explanation of terms>
In this specification, “X to Y” (X and Y are arbitrary numbers) means “X or more and Y or less” unless otherwise specified, and “preferably larger than X” or “preferably "Is smaller than Y".
In addition, when “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.

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

<Example 1>
An ultraviolet absorber-containing polycarbonate resin (“Panlite 5250ZS” manufactured by Teijin Chemicals Ltd.) as an ultraviolet absorbing layer constituting resin and a polycarbonate resin (“Novalex 7027U” produced by Mitsubishi Engineering Plastics) as a transparent resin plate constituting resin, Each was put into a separate hopper of an extruder, both were melted at a temperature of 280 ° C., and then co-extruded using a multi-manifold die. Then, the polycarbonate resin side of the ultraviolet absorbing layer 4 was set as the mirror metal roll side, and the opposite The surface was brought into contact with a metal roll engraved in a prism shape with a non-isosceles triangle and a height of 508 μm, and a prism surface 3 was provided on the opposite surface to cool and solidify to obtain a transparent sheet with a prism surface.

The transparent sheet with a prism surface had a two-type two-layer configuration in which the total thickness was 2.5 mm and the thickness ratio of the UV absorbing layer / transparent resin layer was 40/2460.
The formed prism surface 3 has triangular prism unit prisms 3a each having a non-isosceles triangle cross section arranged in parallel in the width direction, and each unit prism 3a has a round top. The top angle α was 122.5 °, the outdoor side bottom angle β30 °, the indoor side bottom angle γ27.5 °, the prism pitch L6 mm, and the unit prism 3a height H1.64 mm.

<Example 2>
In the same manner as in Example 1, triangular prism unit prisms 3a each having a non-isosceles triangle cross section are continuously arranged in the width direction, and each unit prism 3a is rounded at the top. An angle α: 125 °, an outdoor-side bottom angle β30 °, an indoor-side bottom angle γ25 °, a prism pitch L6 mm, and a unit prism 3a height H1.55 mm were obtained.

<Comparative Example 1>
In the same manner as in Example 1, triangular prism unit prisms 3a each having an isosceles triangle cross section are continuously arranged in the width direction, and each unit prism 3a has a top angle α of 120 ° and an outdoor side bottom portion. A transparent sheet with a prism surface having an angle β30 °, an indoor side bottom angle γ30 °, a prism pitch L6 mm, and a height H1.73 mm of the unit prism 3a was obtained.

<Simulation test>
Using the simulation software, the following simulation was performed assuming that the sheets obtained in the examples and comparative examples were used as a light shelf.

FIG. 6 shows a light guide plate (0.5 m in length and 2 m in width) obtained by cutting the sheets obtained in the above examples and comparative examples using illumination design analysis software (product name “Light Tools”). Each numerical value was entered assuming that it would be installed as a light shelf in a building with the structure and dimensions shown in.
Assuming that sunlight at the south-middle altitude at the winter solstice in Tokyo (31 °, installation direction: unit prism length direction is 3 o'clock) is incident on the entire surface of the sample (light shelf) Enter a numerical value, and simulate the distance X and the reflection angle θ from the light shelf indoor side edge of the reflected light that is reflected to the innermost part of the reflected light that is reflected to the ceiling side. The distance X was calculated.

  Considering the above simulation results and the simulation results not shown here in total, a prism having a configuration in which triangular unit prisms are continuously arranged in the width direction on the lower surface side of the transparent resin plate. When a light guide plate having a surface is used as a light shelf, if the apex angle α of the unit prism 3a constituting the prism surface 3 is 120 ° or more and less than 170 °, the amount of sunlight reflected to the upper side of the light guide plate in winter It has been found that the amount of light increases sufficiently, and the illuminance in the room can be increased by taking light into the room.

  Further, in the winter season, from the viewpoint of allowing the reflected light reflected on the ceiling side to be reflected further into the interior of the room, the indoor side bottom angle γ of the unit prism 3a constituting the prism surface 3 is lower than the outdoor side bottom angle β. It has been found that the angle is important, and it is particularly preferable that the indoor side bottom angle γ is 1 to 10 ° lower than the outdoor side bottom angle β.

DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Transparent resin plate 3 Prism surface 3a Unit prism 4 Ultraviolet absorption layer

Claims (3)

A light guide plate used as a material for building fences or light shelves,
A unit constituting the prism surface 3 is provided with a prism surface 3 having a configuration in which triangular unit prisms 3 a are continuously arranged in the width direction on the opposite side of the light incident side of the transparent resin plate 2. The top angle α of the prism 3a is not less than 120 ° and less than 170 °, and there is a difference between one bottom angle β and the other bottom angle γ in the unit prism 3a, and the length direction of the unit prism is A light guide plate that is parallel to the housing and has a smaller one of the two bottom angles β and γ of the unit prism 3a positioned on the housing side .   The light guide plate according to claim 1, wherein an angle difference between the bottom angle β and the bottom angle γ in the unit prism 3a is 1 to 30 °.   The light-guide plate of Claim 1 or 2 provided with the ultraviolet absorption layer, the heat ray absorption layer, or both of these on the upper surface of the transparent resin plate.

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