JPH11224510A - Surface light source device - Google Patents

Abstract

(57) Abstract: In a surface light source device, instead of providing a diffusion pattern on a light guide plate itself, a diffusion pattern is formed on a thin light guide plate, and the light guide plate is attached to a light guide plate without a pattern. A large-sized light guide plate with a diffusion pattern can be easily and inexpensively manufactured, which is suitable for a lighting device. SOLUTION: A light guide plate 2 and a thin transparent medium 8 with a pattern are provided.
Are bonded with a transparent resin 9. As the thin transparent medium 8, a sheet-like material having a thickness smaller than that of the light guide plate 2 can be used, and a large-sized light guide plate with a diffusion pattern can be easily and inexpensively manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device which spreads and emits light from a point or linear light source in a planar manner, and more particularly to a technique applicable to indoor lighting.

[0002]

2. Description of the Related Art Conventionally, as a light source of this type of surface light source device, an LED which is a solid-state light emitting device using a semiconductor has been widely used. It has the feature that it has a long life, and is used for electronic bulletin boards and liquid crystal (LCD) backlights of various devices. Originally, a surface light source device using an LED, which is a point light source, as a light source is converted into a surface light source by using a light guide plate.

A conventional surface light source device used for a backlight or the like of an LCD is shown in a perspective view of FIG. 10 and a sectional view of FIG. The surface light source device 100 includes a light guide plate 2 for confining light, a light emitting unit 3, and a reflection plate 4. The light guide plate 2 is formed of a transparent resin having a large refractive index such as a polycarbonate resin or a methacryl resin, and a diffusion pattern P is formed on the lower surface of the light guide plate 2 by uneven processing or dot printing of a diffuse reflection ink. I have.
The light emitting section 3 is a circuit board 3a on which a plurality of so-called point light sources 3b such as light emitting diodes (LEDs) are mounted, and faces a side surface (light incident surface 7) of the light guide plate 2.
The reflection plate 4 is formed of, for example, a white resin sheet having a high reflectance, and has both sides adhered to the lower surface of the light guide plate 2 by a double-sided tape 12.

[0004] As shown in FIG.
The light f emitted from the light guide surface 2 from the light incident surface 7 to the inside of the light guide plate 2 is confined inside the light guide plate 2 by being totally reflected inside the light guide plate 2. When the light f inside the light guide plate 2 enters the diffusion pattern P, the light f is diffused and reflected, and the light exit surface 6
The light f reflected toward the light at an angle smaller than the critical angle of total reflection is extracted from the light exit surface 6 to the outside. Further, the light f transmitted through a portion of the lower surface of the light guide plate 2 where the diffusion pattern P does not exist is reflected by the reflection plate 4 and again.
Since the light returns to the inside, loss of light quantity from the lower surface of the light guide plate 2 is prevented.

[0005]

By the way, at present, there is a demand for the development of a new type of indoor lighting device (future light) which is energy-efficient and durable and durable. There is a plan to reduce power consumption to approximately 1/8 of incandescent lamps and approximately 1/2 of fluorescent lamps by using them as appliances, and to increase the service life.

Therefore, in order to realize such a concept, the use of the above-described surface light source device using LEDs in the field of lighting such as indoors was examined. However, a surface light source device used for an LCD backlight or the like has a size of at most about 6 inches (15.2 cm). In contrast, with general indoor lighting fixtures,
The surface light source must be capable of uniformly illuminating a wide range, and a size of several meters (m) is required. That is, in the case of illumination, the size of the light guide plate is ten times or more the size of the conventional backlight.

[0007] The above-mentioned conventional light guide plate with a diffusion pattern is prepared by raising a metal mold based on an original master on which a pattern is formed by etching or the like, and then manufacturing it by injection molding, or printing diffuse reflection ink dots on the light guide plate. Since it can be manufactured by a mold,
The emission pattern is integrated with the light guide plate. On the other hand, when the light guide plate has a large area of several meters in size,
A large mold is required, and it is difficult to manufacture such a mold and to print a pattern on the large light guide plate itself with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. Instead of providing a diffusion pattern on the light guide plate itself, the present invention provides a method for producing a diffusion pattern on a thin light guide plate.
By attaching the light guide plate to a light guide plate without a pattern, a large size light guide plate with a diffusion pattern can be easily and inexpensively manufactured without the need for an expensive and large mold. An object is to provide a suitable surface light source device.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a surface light source device for spreading and emitting light from a point or linear light source in a planar manner, wherein the light guide plate and an end face of the light guide plate are provided. A light source installed so that light is incident from the light source, and a thin plate-shaped transparent medium formed with a pattern having a light diffusion action, wherein the light guide plate and the thin plate-shaped transparent medium are bonded with a transparent resin. . In this configuration, a light guide plate with a diffusion pattern can be manufactured by attaching a thin plate-like transparent medium to the light guide plate with a transparent resin. As this thin plate-shaped transparent medium, it is possible to use a thinner medium than the light guide plate, so that a large-sized light guide plate with a diffusion pattern can be easily and inexpensively manufactured as compared with the conventional configuration and manufacturing method. can do.

Further, as the thin plate-shaped transparent medium, a sheet-shaped transparent medium can be used. In this configuration, a large-sized light guide plate with a diffusion pattern can be easily manufactured.

Further, as the thin plate-shaped transparent medium, a medium divided into two or more sheets can be used. In this configuration, a large-sized light guide plate with a diffusion pattern can be easily manufactured.

Further, it is assumed that the pattern having the light diffusing action is formed of a dot-like pattern, and a plurality of through holes smaller than the one dot are provided in the thin plate-like transparent medium. In this configuration, when the thin plate-shaped transparent medium is attached to the light guide plate, the removal of bubbles is facilitated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic external view of a light guide type lighting device according to an embodiment of the surface light source device of the present invention,
FIG. 2 is an enlarged view of a portion A in FIG. Light-guided lighting device 1
Is a light guide plate 2 made of a transparent acrylic resin or the like; a point or linear light source 3 installed so that light is incident from an end face (light incident surface) of the light guide plate 2; Surface (Fig. 1
The light guide plate 2 includes a thin transparent medium 8 having a light diffusion pattern 5 formed on the lower surface of the light guide plate 2 and a thin plate-like reflector 4 disposed on the non-emission side surface of the light guide plate 2. And the thin transparent medium 8 are adhered with a transparent resin 9. The light guide plate 2 is provided with no pattern, whereas the thin transparent medium 8 is provided with a dot pattern 5 made of an epoxy resin or the like having a light diffusion effect. The dot pattern 5 is distributed over the entire surface of the thin transparent medium 8,
It has the function of emitting light uniformly from the light emitting surface. As the light source 3, an LED module that mixes white or three colors of R, G, and B may be used. The size of the light guide plate 2 is, for example, 1 m.
X 1 m is used.

FIG. 3 is an end view of the light guide type illumination device 1, and FIG.
(A), (b), and (c) are enlarged views of a portion B in FIG. 3, showing three examples of patterns formed on the thin transparent medium 8. FIG. 4 (a) shows a dot-shaped concave pattern 5a formed on the non-adhesive side of the thin transparent medium 8, and FIG. 4 (b) shows a dot-shaped convex pattern 5b formed on the non-adhesive side of the thin transparent medium 8. ,
(C) shows a pattern in which a dot-shaped diffusion ink is formed on the adhesive side of the thin transparent medium 8. The pattern is provided with a coarse and dense distribution so that light can be emitted uniformly, as described later. The patterns 5a and 5b can form irregularities on the sheet-shaped thin transparent medium 8 by mechanical or chemical treatment, and the pattern 5c can be formed by printing, and both can facilitate the production of a large area pattern. The thin transparent medium 8 may be a combination of a plurality of thin transparent media. In the case of the pattern 5c using the diffusion ink, it is easy to manufacture, and by using an ink having a refractive index different from that of the transparent resin 9, there may be a pattern on the bonding side of the thin transparent medium 8; Also.

The mechanism for extracting light from the light exit surface of the light guide type illumination device 1 is basically the same as that described in the above-mentioned prior art, and the light introduced into the light guide plate 2 from the light incident surface. Are totally reflected in the light guide plate 2 and the diffusion pattern 5 (5a, 5
b, 5c), the light is diffusely reflected, and the light reflected by the reflector 4 toward the light emitting surface at an angle smaller than the critical angle of total reflection is emitted to the outside. Refractive index n1 of light guide plate 2
The relationship between the refractive index n2 of the transparent resin 9 and the refractive index n3 of the patterned thin transparent medium 8 preferably satisfies n1 ≦ n2 ≦ n3 in order to improve the emission efficiency.

FIG. 5 is a plan view showing another embodiment of the thin transparent medium with a pattern in the light guide type illumination device.
The thin transparent medium 8 has an air hole 10 smaller than one dot forming the pattern 5. With this configuration, it is possible to prevent bubbles from being generated between the thin transparent medium 8 and the light guide plate 2 when the thin transparent medium 8 is adhered to the light guide plate 2 with the transparent resin 9. Since the air holes 10 also have a light diffusion effect, they are sufficiently smaller than one dot of the pattern 5 (several tens to 100 μm). Other configurations are the same as the basic configuration of the first embodiment.

FIG. 6 is a plan view showing still another embodiment of the thin transparent medium with a pattern in the light guide type illumination device. In this thin transparent medium 8, a hole 5d for venting air is provided.
To form a diffusion pattern. This hole 5d can be used for both air release and diffusion. In order to enhance the efficiency of extracting light from the light guide plate 2, it is desirable to arrange the diffusion patterns formed of the holes 5d at a high density.

FIG. 7 is an end view showing another embodiment of a method of bonding a thin transparent medium with a pattern to the light guide plate 2. In this example, instead of the transparent resin 9 of the above embodiment,
The thin transparent medium 8 is attached to the light guide plate 2 using a double-sided adhesive tape 9. The double-sided adhesive tape 9 is previously attached to the thin transparent medium 8
By attaching to the side, assembly becomes easy.

FIG. 8 is a schematic diagram showing an embodiment of a diffusion pattern when the light source 3 is linear. An LED module is used as the light source 3, and the diffusion pattern 5 is formed by printing in a linear shape. In order to improve the uniformity of the emitted light,
The closer to the LED module, the coarser, and the farther it is, the denser. Both pattern width and shortest pattern pitch are 3
It is about 00 μm.

FIG. 9 is a schematic diagram showing an embodiment of a diffusion pattern when the light source 3 is a point light source (including a case where the light source 3 can be almost regarded as a point light source). In order to improve the uniformity of the emitted light, the diffusion pattern 5 is made concentric with the light source 3 as a center. The diffusion pattern 5 is rougher as it is closer to the light source 3 and denser as it is farther from the light source 3. Each of the minimum pattern size and the minimum inter-pattern distance is about 300 μm. By adopting a configuration in which the pattern 5 is provided on the thin transparent medium 8 as described above, a pattern can be formed on a sheet, and thus a large-area pattern can be easily formed.

The present invention is not limited to the configuration of the above-described embodiment, but can be variously modified. In short, a diffusion pattern is prepared in advance on the thin transparent medium 8 side, and these are pasted on the light guide plate 2 having no pattern. The above-described effects can be obtained by manufacturing the lighting device with the lighting device. Although not shown above, the thin transparent medium 8 may be divided into a plurality of pieces. Further, the reflector 4 in the above embodiment may not be provided, and in that case, light is emitted to both surfaces. Further, a display plate for displaying a static image can be formed by using the surface light source device.

[0022]

As described above, according to the present invention, a light guide plate and a plate-shaped transparent medium having a pattern having a light diffusion action are bonded with a transparent resin to produce a light guide plate with a diffusion pattern. Therefore, the diffusion pattern can be formed on a sheet-like member or the like separate from the light guide plate. A light plate can be manufactured, and a surface light source device suitable for a lighting device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic external view of a light guide lighting device according to an embodiment of a surface light source device of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is an end view of the light guide illumination device.

FIGS. 4 (a), (b) and (c) are enlarged views of a portion B in FIG. 3;

FIG. 5 is a plan view showing another embodiment of a thin transparent medium with a pattern in the light guide type illumination device.

FIG. 6 is a plan view showing still another embodiment of the thin transparent medium with a pattern in the light guide type illumination device.

FIG. 7 is an end view showing another embodiment of a method of bonding a thin transparent medium with a pattern to a light guide plate.

FIG. 8 is a schematic diagram according to an embodiment of a diffusion pattern when the light source is linear.

FIG. 9 is a schematic diagram according to an embodiment of a diffusion pattern when the light source is a point light source.

FIG. 10 is a perspective view of a conventional surface light source device.

FIG. 11 is a cross-sectional view of a conventional surface light source device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-guide type illuminating device 2 Light guide plate 3 Light source 5, 5a, 5b, 5c Pattern for light diffusion 5d hole 8 Thin transparent medium (thin-plate transparent medium) 9 Transparent resin 10 Air hole (through hole)

Claims (4)

[Claims] 1. A surface light source device which spreads and emits light from a point or linear light source in a planar manner, comprising: a light guide plate; a light source installed so that light is incident from an end face of the light guide plate; A surface light source device, comprising: a thin plate-shaped transparent medium having a pattern having an effect, wherein the light guide plate and the thin plate-shaped transparent medium are bonded with a transparent resin. 2. The surface light source device according to claim 1, wherein the thin plate-shaped transparent medium has a sheet shape. 3. The surface light source device according to claim 1, wherein the thin plate-shaped transparent medium is divided into two or more sheets. 4. The method according to claim 1, wherein the pattern having the light diffusing action is formed of a dot-like pattern, and
4. The surface light source device according to claim 1, wherein a plurality of through holes smaller than one dot are provided.