JPH02247687A - Surface illuminator - Google Patents

Abstract

PURPOSE:To attain uniform illumination by alternately laminating plural light transmission plates in such a way that the direction of their incident end surfaces is reversed. CONSTITUTION:A light transmission body 2 is formed in such a way that the direction of the end surfaces of adjacent light transmission plates 4 are alternately reversed and these plural plates 4 are laminated in a thickness direction, and lamps 1 are provided in parallel with incident surfaces 2a. The incident light beams of the lamp 1 are guided to the side of an end surface 4d from the end surfaces 4a of the light transmission plates 4 by the total reflection of the front surface 4c, etc. Direct light beams from the lamp 1 and reflected light beams from the surface 4c are diffused on the rear surface 4b, so that the whole of the plate 4 uniformly emits light. Out of the light beams diffused and reflected by the surface 4d, those below the critical angle of the surface 4c passing through the surface 4c, are diffused by the diffusing plate 3, become uniform light beams, and can uniformly illuminate the surface of a display plate from the back.

Description

[Detailed Description of the Invention] [Industrial Field of Application 1] The present invention relates to a surface illumination device that is used for illuminated signs, guidance indicator lights, etc., and illuminates a translucent display body from the rear side. be.

[Prior Art 1 A conventional surface illumination device is shown in FIG. 6. This surface lighting device is
The light from the lamp 1 is incident on a light guide 2 made of a transparent material, and the entire light guide 2 emits light to produce a display (not shown).
This is the so-called F-4111 type which indirectly illuminates the area. In this surface illumination device, in order to brightly illuminate the display body, half of the display body is illuminated using the light guide 2 and the lamp 1.

Here, the light guides 2 are arranged side by side with their narrow end faces facing rl, and the circle of the lamp l enters from each wide end face. A diffusion plate 3 is disposed above the two light guides 2 so that the light emitted from the light guides 2 is uniformly irradiated onto the display.

E Problem to be Solved by the Invention 1 However, in this surface illumination device, the range in which the display body is illuminated by the respective guides and body 2 is divided at the central part of the diffuser plate 3. If there are variations in the brightness, there is a problem that uneven brightness occurs at the center of the diffuser plate 3.

The present invention has been made in view of the above points, and its f
One object of the present invention is to provide a surface illumination device with less uneven brightness when two lamps are provided.

Means for Solving Problem 1 J In order to achieve the above [Object 1], the present invention diffuses the light incident from one end face while guiding it to the side opposite to this incident end face, so that the entire body emits light uniformly. The light guide is formed by laminating a plurality of thin plate-shaped light guide plates with the directions of the incident end faces alternately opposite to each other, and the incident end faces of the light guide plates are arranged in a row with their longitudinal directions aligned with the stacking direction of the light guide plates. Light sources are arranged in parallel on the surface of the light guide.

[Function] As described above, the present invention crosses the direction of the incident end surface of the light guide plate, which diffuses the light incident from one end surface while guiding it to the side opposite to this incident end surface, so that the entire light emitting surface emits light uniformly. By stacking a plurality of light guide plates in opposite directions to form a light guide, adjacent light guide plates are made to emit light from each type of lamp, so that the light from both lamps is finely mixed. Even if there are variations in the luminous flux or color of the lamp, the uneven brightness of the light guide is reduced.

Example 1 In this example, the light guide 2 is formed by laminating a plurality of thin light guide plates 4, as shown in FIG. 1(a).

As shown in FIG. 2, the light guide plate 4 is formed into a substantially right triangular shape when viewed from the side, and is formed so that it becomes thinner toward the tip when viewed from above. When two light guide plates 4 are combined with their directions reversed, they form a rectangle. Each surface of the light guide plate 4 is formed as a smooth surface except for the lower surface 41z, and the outer surface of the 'F surface 4b is painted white to serve as a diffuse reflection surface. In addition, 1
The surface 4b may be formed into a smooth surface in a portion close to the lamp 1, and the other portions may be subjected to a diffusion treatment, or a reflecting plate may be attached in close contact with the surface 4b. In this light guide plate 4, the wide end surface 4a is used as an incident surface, and the curved upper surface 4c is used as an output surface.

Further, the light guide plate 4 is made of a transparent material such as plastic or plastic with a refractive index of 1.4 to 1.6.
The light entering from the end face 4a is totally reflected by the smooth surface. Note that the upper surface 4c is formed into a curved surface with a curvature that uniformly reflects incident light from the end surface 4a to the lower surface 4b.
It also functions as a reflecting surface that guides the incident light from the end surface 4a toward the end surface 4d.

Further, in this embodiment, an end surface 4d is provided on the opposite side to the end surface 4a, which is the incident surface, but the end surface 4d may have a pointed r-shape without this end surface 4d.

As shown in FIG. 1(a), the light guide 2 is formed by stacking a plurality of light guide plates 4 in the thickness direction, with the end faces 4a of adjacent light guide plates 4 alternately facing in opposite directions. It is. Then, lamps 1 are arranged in parallel along both end surfaces where the end surfaces 4a of each light guide @ 4 are arranged, that is, along the incident surface 2 of the light guide 2, and above the light guide plate 2, as shown in FIG. As shown in (1)), a diffusion plate 3 is provided. t3, diffusion Jfi, 3 may be formed of, for example, a milky white resin, or may be made of suriplus.

In this embodiment, as shown in FIG.
The light from the lamp 1 entering from a is guided to the end surface 4dllll by total reflection on the top surface 40, etc., and the direct light from the lamp 1 and the reflected light from the top surface 4c49 are diffused and guided by the bottom surface 4b, which is a diffuse reflection surface. The entire light plate 4 emits light uniformly. Of the light diffusely reflected by the lower surface 4b, light below the critical angle of the upper surface 4C passes through the upper surface 4c and is transmitted through the diffuser plate 3.
Then, the light from the upper surface 4c is diffused by the diffuser plate 3 to obtain uniform light, and the display panel can be uniformly illuminated from the back side. The display body can be brightly illuminated by illuminating half the area of the display body with the four groups of light plates.In addition, one light guide plate 4 is thin, and the adjacent light guide plates 4 each use the light of the lamp 1. Since the light from both lamps 1 is fine (mixed), even if there are variations in the luminous flux or color of the lamps 1, the uneven brightness of the light guide 2 is reduced, and the display can be illuminated uniformly. If the light guide 2 is formed by laminating a plurality of light guide plates 4, even if the display body has various shapes with different lengths in the longitudinal direction of the pump 1, it can be changed by changing the number of layers to be laminated. The light guide 2 that corresponds to the above-mentioned length of the display body can be easily formed.

By the way, in place of the light guide 411f4 used in each of the above embodiments, one shown in FIGS. 4(a) to 4(c) may be used.

The light guide plate 5 in Figure H4 (a) is the upper surface 4 of the light guide plate 4 in Figure 2.
It has a shape in which b and 1 side 4c are upside down, and the top surface 5c is a smooth surface except for the top surface 5c, and the top surface 5c is a diffusing and transmitting surface. Similar to the top surfaces 4b and 111 of the light guide plate 4, the dot surface 51) is formed into a curved surface with a curvature that uniformly reflects incident light from the end surface 5a onto the top surface 5c, so that the end surface 5a reflects all of the incident light. It is designed to be reflective. Further, the upper surface 5c is, for example, a diffuser-transmitting surface with a diameter of 70 mm. Note that the lower surface 5b may be made into a complete total reflection surface by attaching a reflecting plate ff1ffi to the lower surface 5b or by vapor depositing aluminum.

In this light guide plate 5, the circle of the lamp 1 incident from the i-plane 5g is guided to the end surface 5d side by reflection from the lower surface 5b, etc., and the direct light from the lamp 1 and Reflected light from the lower surface 5b and the like is diffused and transmitted, and uniform light is obtained from the upper surface 5c.

The light guide plate 6 shown in FIG. 4(b) is made of a transparent material and formed into a rectangular parallelepiped-shaped thin plate, and each surface is formed to be a smooth surface. In this light guide plate 6, an opacifying agent 7 as a diffusing agent for diffusing the light of the lamp 1 is mixed inside, and this opacifying agent 7 is applied to an end surface 6d opposite from the end surface 6a where the light of the lamp 1 is incident. The light guide plate 6 also uses the upper surface 6c as the output surface.The lower surface 6b is coated with aluminum evaporation or the like. Reflection treatment may be applied.This light guide plate 6 also guides the light incident from the end surface 6a to the end i[6d side by reflection from each surface, and diffuses the light by the opacifier 7. The light guide plate 6 is made to emit light uniformly, and uniform light can be obtained from the upper surface 6c.

The light guide plate 8 in FIG. 4(c) has a shape aligned with the light guide plate 5 in FIG. 4(a), and the lower surface 8b of the light guide plate 8 in FIG.
It differs from the light guide plate 5 in that it is processed into a lenel shape. In addition,
The lower surface 8b is subjected to a reflective treatment such as aluminum vapor deposition to increase light diffusivity.

Furthermore, although not shown, the shape of the light guide plate 4 seen from above shown in FIG. 2 is not made into a shape that tapers toward the tip.
The light guide plate may have a uniform lv angle of 4°.

By the way, if the light guide plate 4 in Fig. 2 is formed so that it becomes thinner toward the tip when viewed from above, and the two light guide plates 4 are combined with the directions of the tapered ends reversed, a rectangular shape is formed. The reason for the formation is as follows. In other words, if the light guide plate 2 is formed by stacking light guide plates 4 degrees with a uniform thickness when viewed from above at C7, the incident surface 2g' of this light guide 2 is as shown in Fig. 5 (1)). As shown in Figure 5 (
This is because when the light guide plate 2 is formed by laminating the light guide plates 4 as shown in a), the incident IM product of the incident surface 2a of the light guide plate 2 can be widened. That is, the light guide plate 2 shown in FIG. [4] The luminous efficiency of the light guide plate 2 can be increased. Note that even if the light guide plates 5, 6, and 8 in FIG. 4 are formed to have the same upper surface shape as in FIG. , the luminous efficiency of the light guide 2 can be increased.

1 Effects of the Invention 1 As described above, the present invention provides a plurality of thin plate-shaped light guide plates that diffuse light incident from one end face while guiding it to the incident end face and the other side, thereby uniformly emitting light as a whole. , forming the above-mentioned light guide by forming H4 layers with the directions of the incident end faces alternately opposite;
Since the light sources are arranged in parallel on the surface of the light guide body on which the incident end surfaces of the light guide plates are arranged in parallel with the stacking direction of the light guide plates, each light guide plate in contact with H4 can be used as a light source such as a different lamp. The light from both light sources can be mixed finely, so even if there are variations in the luminous flux or color of the light source, uneven brightness of the light guide is reduced, and the display can be illuminated uniformly. effective. Moreover, since the light guide is formed by laminating multiple light guide plates, even if the display body has various shapes with different lengths in the direction of the light source, just change the number of light guide plates to be laminated. This also has the effect of easily forming a light guide according to the length of the display body.

[Brief explanation of drawings]

FIG. 1 (LL) is a plan view of an embodiment of the present invention with the diffuser plate removed, FIG. 1 (b) is a cross-sectional view showing the overall configuration, and FIG. 4(a) to 4(e) are explanatory diagrams of a light guide plate of a different shape. FIG. 11115(a) is a partial perspective view of the same light guide, and FIG. 6B is a partial perspective view of a light guide formed by a light guide plate of a different shape, and FIG. 6 is a perspective view of a conventional example. 1 lamp, 2 light guide, 4 light guide plate, 4al end face,
4c is the top surface. Representing Patent Attorney I1 [fl 托上Figure 3 (b) (C) 2 Figure 5

Claims (2)

[Claims] (1) In a surface illumination device in which linear light sources are arranged in parallel on each of both end faces of a light guide, and light from the light guide emitted by the light source illuminates a translucent display, the light enters from one end face. The above-mentioned light guide is made by stacking a plurality of thin plate-like light guide plates, which emit light uniformly throughout the whole while guiding the light to the opposite side of the incident end face, with the direction of the incident end face being alternately reversed. A surface illuminating device in which light sources are arranged in parallel on a surface of a light guide body in which the incident end faces of the light guide plates are arranged in a row with the longitudinal direction thereof aligned with the stacking direction of the light guide plates. (2) The shape of the output surface of the light guide plate is formed to become thinner toward the side opposite to the incident end surface, and the shape is formed so that when two light guide plates are stacked with the directions of the incident end surfaces opposite to each other, it becomes a rectangle. A surface illumination device according to claim 1, comprising: