JPH0979872A - Light guide plate for transmission lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a dial easily visible by unifying the intensity of the illumination on the dial of an operation recorder. SOLUTION: This transmission lighting system is provided with a light guide plate 6 capable of guiding part of the light emitted from a light source 7 for display at a prescribed opening section, a translucent display means 5 arranged on one side face of the light guide plate 6, and a reflecting structure reflecting the light from the light source 7 to the display means 5 side. The reflecting structure is a recess 8 having an inner wall face curved toward the display means 5 at part of the light guide plate 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a light guide plate for guiding light from a light source to display in a predetermined opening, and a transmission structure having a reflecting structure for reflecting light from the light source in the thickness direction of the light guide plate. The present invention relates to a light guide plate of a lighting device,
The present invention relates to a light guide plate of a transillumination device which is improved so that a display on an instrument can be performed well.

[0002]

2. Description of the Related Art Conventionally, there are various types of devices that perform various displays by illumination. As this type of display device, there are instrumentation of mechanical devices and instruments such as vehicles. The instruments have various types and forms depending on the purpose of use, place of use, conditions of use, etc. One example will be described with reference to the drawings.

In FIG. 3, for example, light emitted from a light source (not shown) 12 in a direction orthogonal to the thickness of the plate-shaped light guide 9 is shown.
(A light beam is schematically shown in the figure) is guided, but as shown in FIG. 3, in the light guide type instruments utilizing the total reflection of light, as shown in FIG. Parallel plane 1
1 has a configuration in which a concave portion 30 is formed, and the inclined surface 10 is used to reflect light to the display portion 13 side. In the light guide 9 configured as described above, the light 12 emitted from the light guide 9 is formed at the position where the inclined surface 10 is formed.
Was obtained and a bright portion was formed, and the emitted light 12 was not obtained at a portion where a surface parallel to the parallel rays was formed, and a dark portion was generated.

FIG. 4 shows the state of light reflection in another conventional example in which a triangular recess 40 is formed in the light guide 9. In the drawing, when light rays are incident on the triangular recess 40 from the left and right directions of the light guide 9, the top portion 10a, which is the approaching area of the left and right light rays reaching the inclined surface 10, is an unnecessary line as the strongest portion. Is easy to appear. Especially,
This phenomenon becomes more prominent as the gap S between the top 10a of the triangular recess 40 and the dial 5 is shorter.

[0005]

SUMMARY OF THE INVENTION The present invention has a problem that it is difficult to display a uniform image due to the occurrence of a bright portion and a dark portion as in the above-mentioned conventional example, and further, as shown in FIG. In view of the problem that unnecessary lines appear, in the light guide plate of the transillumination device, the light guide plate of the transillumination device that enables uniform and uniform brightness by eliminating variations in the brightness level of a desired region where light is desired to be reflected. The purpose is to provide.

[0006]

The above object of the present invention is to provide a light guide plate capable of guiding a part of the light emitted from the light source for displaying at a predetermined opening, and the light guide plate is provided on one side surface of the light guide plate. In a light guide plate of a transillumination device having a light-transmissive display means and a reflection structure for reflecting light from the light source on the display means side, the reflection structure displays on a part of the light guide plate. This can be solved by the light guide plate of the transillumination device, which is a recess having an inner wall surface that curves toward the means side.

As a preferred embodiment, the shape of the inner wall surface of the recess may be a spherical recess having a shape of a part of a spherical surface.

According to the above-mentioned light guide plate of the present invention, since it is provided with the concave portion of the inner wall surface formed in a spherical shape,
When the light coming from the direction orthogonal to the thickness direction of the light guide plate hits the inner wall surface and is reflected in the thickness direction, the traveling direction of the light after reflection is along the wall surface depending on the position of the inner wall surface. It can be gradually changed, the dispersion of the reflected light can be appropriately adjusted, and the intensity of the brightness can avoid the generation of an unnecessary pattern.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a light guide plate of a transillumination device according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an instrument equipped with a light guide plate according to the present invention. For example, an operation recorder 1 such as a vehicle speedometer.
FIG. In FIG. 1, an operation recorder 1 includes, for example, a front glass (not shown), a case body 2, a pointer 3, and a dial 5 which is a display unit for displaying character symbols, and the pointer on the back side of the dial 5. An internal unit 4 for rotating 3 and a light source 7 (actually, a plurality are provided) for illuminating the dial 5, and a reflection for reflecting the light from the light source 7 on the dial 5 side. It has a concave portion 8 which is a structure.

The reflecting structure has a part of the light guide plate 6 having an inner wall surface that curves toward the display means 5. The shape such as the curvature of the inner wall surface is not particularly limited as long as the light incident along the dial plate 5 is reflected in the thickness direction of the light guide plate 6. As shown in the figure, in the present embodiment, the shape of the inner wall surface of the recess 8 is a spherical recess made up of a part of the spherical surface.

FIG. 2 shows an enlarged vertical section of the recess 8. In FIG. 2, the light rays reaching the spherical concave portion 8 are directly transmitted through the light guide plate 6 from a plurality of light sources 7 arranged as shown in FIG. 1 (schematically shown by a straight line). Light) and indirect rays that the light of the light source 7 reaches by being appropriately reflected by the outer circumference of the light guide plate 6 in the thickness direction and the like, but here, for the sake of easy understanding, they are formed on the light guide plate 6. Light reflected by the spherical recess 8 (emitted light)
3A and 3B schematically show the states of the light rays in the light guide plate 6 in the vicinity of the spherical concave portion 8 and the spherical concave portion 8. As shown in the figure, the spherical concave portion 8 reflects the light rays inside the light guide plate 6 to form outgoing light 12 and guide it toward the dial plate 5.

As described above, since the concave portion 8 is provided with the inner wall surface 20 formed in a spherical shape, for example, the light coming from the direction orthogonal to the thickness direction of the light guide plate is formed on the inner wall surface 2.
When the light strikes 0 and is reflected in the thickness direction, the traveling direction of the reflected light is gradually changed along the wall by the position of the inner wall, and the light is dispersed as illustrated. And
Since the central portion of the display unit 13 is illuminated by light coming from the left and right in the figure (actually coming from the entire circumferential direction), the density of light rays does not decrease even when compared with the outer portion of the display unit 13, As a result, it is possible to provide uniform light. Therefore, it is possible to appropriately disperse the reflected light by the concave portion 8 and to avoid the generation of an unnecessary pattern depending on the intensity of the brightness.

Although the above-described embodiments have been described with respect to the case where the present invention is applied to an instrument such as a speedometer, the present invention utilizes not only the operation recorder but also various instruments and this kind of light guide plate. Of course, it can be applied to various equipment.

[0015]

As described above, since the light guide plate of the present invention has the inner wall surface having the curved concave portion, the light traveling in the thickness direction of the light guide plate is applied to the inner wall surface. When the light is reflected in the thickness direction, the traveling direction of the reflected light can be gradually changed along the wall surface depending on the position of the light hitting the inner wall surface, and the outer portion and the central portion of the display section can be changed. Even when compared with, it is possible to reduce the difference in the density of the light rays, and it is possible to provide uniform light as a whole, and it is possible to avoid the intensity of brightness and the generation of unnecessary patterns that have conventionally occurred.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an operation recorder to which a light guide plate according to the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG. 1 and is a view showing a state of light rays in a recess.

FIG. 3 is a schematic cross-sectional view showing a state of light rays in a conventional light guide plate.

FIG. 4 is a schematic cross-sectional view showing a state of light rays in a conventional light guide plate.

[Explanation of symbols]

 1 Operation Recorder 2 Case Body 3 Pointer 5 Dial 6 Light Guide 7 Light Source 8 Recess 20 Inner Wall

Claims (2)

[Claims] 1. A light guide plate capable of guiding a part of light emitted from a light source for displaying on a predetermined opening, and a translucent display means is provided on one side surface of the light guide plate. A light guide plate of a transillumination device comprising a reflective structure for reflecting light from the light source on the display means side, wherein the reflective structure is part of the light guide plate and is curved toward the display means side. A light guide plate for a transillumination device, which is a recess having a wall surface. 2. The light guide plate of the transillumination device according to claim 1, wherein the shape of the inner wall surface of the concave portion is a spherical concave portion formed of a part of a spherical surface.