JP2772306B2 - Light guide plate for instrument pointer illumination - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate for illuminating a pointer of an instrument such as a speedometer or a tachometer, which guides light from a light source to the pointer.

[0002]

2. Description of the Related Art Conventionally, as a method of illuminating a pointer or a dial in a dark place of an analog type among instruments such as a speedometer and a tachometer, a pointer and a dial are illuminated by irradiating light from a light source disposed in front of the dial. How to make the dial shine,
Alternatively, there is a method in which light from a light source disposed behind a dial is guided to a pointer or the like by a light guide plate so that the pointer or the like shines.

FIG. 2 shows an example of a light guide plate used in the latter case. The light guide plate 11 is made of a transparent plastic such as an acrylic resin, and has a substantially disk-shaped central portion 12 having a predetermined thickness and a peripheral portion of the central portion 12 protruding substantially perpendicularly to the central portion 12. Light introducing unit 13 (13a, 13b, 13c) for guiding the light from the light source
Etc.). Further, grooves 14 (14a, 14b, 14c) and the like having a predetermined curve are engraved in the central portion 12, and light introduced from central points 13aa, 13bb of the light sources of the light introducing portions 13a, 13b. Is the central part 1
2 when passing through the grooves 14a, 1
The light is reflected by 4b and 14c and concentrated on a conical notch 15 provided substantially at the center of the central portion 12.

FIG. 3 is a sectional view showing a state in which the light guide plate 11 is attached to the back of the dial 8. That is, the light guide plate 11 is attached in close contact with the back surface of the dial 8,
A light source 20 is arranged near the light introducing portion 13a of the light guide plate 11, and the light of the light source 20 is introduced from the light introducing portion 13a and at the interface between the inside and the outside of the central portion 12 of the light guide plate 11. The light advances while repeating the reflection, is reflected on the end face of the notch 15, and is introduced into the base 9 a of the hands 9 from the opening 8 a through which the hands 9 c of the dial 8 pass. The light introduced into the base 9a is reflected at a substantially right angle here, is incident on the indicator of the pointer 9, repeats reflection at the interface between the inside and the outside, and the hot stamp provided on the back surface of the indicator of the pointer 9 Light is emitted when the light enters the surface 9b, and the pointer 9 shines and is visually recognized.

FIG. 4 shows another example of a light guide plate for illuminating a pointer of an instrument. 4A is a bottom view of the light guide plate 21, FIG. 4B is a side view, FIG.
(D) is a sectional view. The light guide plate 21 also has a substantially disk-shaped central portion 22 having a predetermined thickness similarly to the above-described conventional one, and a light for introducing light from a light source to a symmetrical position of a peripheral portion of the central portion 22. Introducing portions 23a and 23b are provided. The notch 2 at the center of the central portion 22 of the light guide plate 21
5 are three pairs of notches 2 having an inclination angle of about 45 ° from the front surface to the back surface with the center hole 25a symmetrical as shown in FIG.
5b, 25c, and 25d are used to efficiently use the introduced light so as to reflect light at various incident angles. 5A is a plan view of the vicinity of the notch 25, FIG. 5B is an end view of the line CC in FIG.
(C) is an end view of the DD line of (a).

[0006]

However, in the former case, in the repetition of the reflection of light at the central portion 12 of the light guide plate 11, an optical path as shown by the symbol B in FIG. The opening 8 is not reflected by the notch 15 forming the reflection surface, and a part thereof forms the emission surface.
a, and is not introduced into the pointer 9. For this reason, the introduced light introduced into the light guide plate 11 cannot be used efficiently, and there is a problem that the brightness of the pointer 9 is not bright enough. In the latter case, there is another problem that the brightness of the hands may be uneven due to the rotational position of the hands.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light guide plate for illuminating a pointer of an instrument which can efficiently guide light from a light source to the pointer and hardly cause luminance unevenness due to the rotational position of the pointer.

In order to solve the above-mentioned problems, the present invention relates to a light guide plate for illuminating a pointer of an instrument, which comprises: a light introducing portion disposed opposite to a light source; A central portion that is arranged along the back surface of the dial, continuous with the introduction portion, and is formed on the surface of the central portion that propagates the inside while reflecting light introduced from the light introduction portion at the interface, and the surface of the central portion. An emission surface, formed at the central portion,
A reflecting surface that guides the light to the pointer through the emitting surface by reflecting the light propagating in the central portion toward the emitting surface, and the central portion is not reflected by the reflecting surface. And a back surface formed of a concave surface having a substantially constant cross-sectional radius for converging an optical path of the light when guiding the light to the reflection surface while reducing the light emitted from the emission surface. It is characterized by that.

[0008]

According to the present invention, the light introduced from the light source into the light introducing portion is propagated through the inside while being reflected at the interface at the central portion, and guided to the reflecting surface. The light that has propagated in the central portion is reflected by the reflection surface toward the emission surface, and the light is guided to the hands via the emission surface to shine the hands. At that time, the central rear portion reduces the light emitted from the exit surface without being reflected by the reflection surface, and has a substantially constant cross section for converging the optical path of the light when guiding the light to the reflection surface. Since it is formed with a concave surface having a radius of, by improving the use efficiency and transmission efficiency of light introduced into the light guide plate for pointer illumination, the light is guided to the notch without waste and efficiently introduced into the pointer. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those described in the description of the related art are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a sectional view showing a state in which a light guide plate 1 for illuminating a pointer of a meter according to the present invention is arranged in close contact with the back surface of a dial 8. The light guide plate 1 has a substantially disk-shaped central portion 2 having a predetermined thickness, a light introducing portion 3 protruding downward from the central portion 2 at a peripheral edge of the central portion 2, and a central portion 12. And a conical notch 5 provided substantially at the center. The rear surface of the central portion 2 is a concave surface 2 having a substantially constant radius R in cross section.
a. The difference from the conventional light guide plate 11 shown in FIG. 3 is that the rear surface of the central portion 2 of the light guide plate 1 is formed by a concave surface 2a having a substantially constant radius R in cross section.

In this state, light from the light source 20 is
a, the light propagates while being repeatedly reflected at the interface between the inside and the outside of the central portion 2 of the light guide plate 1, and passes through the optical path B generated in the case of the conventional example shown in FIG. Is a notch portion which is reflected by a concave surface (convex surface when viewed from inside the light guide plate) 2a of the central portion 2 and becomes like an optical path B 'and functions as a reflecting surface provided substantially at the center of the central portion 2. It is led to 5. As described above, the light is converged by the shape of the concave surface 2a of the central portion 2 while being repeatedly reflected at the interface between the inside and the outside of the central portion 2 of the light guide plate 1, and is guided to the notch portion 5 with the transmission efficiency improved. I will be. The light guided to the notch 5 is
The pointer shaft 9 c of the dial 8 is reflected by the end face of the notch 5.
The needle 9 is introduced into the base 9a of the pointer 9 through an opening 8a (a part of the opening 8a forms an emission surface) through which the light passes. The light introduced into the base 9a is reflected at a substantially right angle at this point, and is guided to the pointing portion of the pointer 9, and further the reflection is repeated at the interface between the inside and the outside of the pointing portion of the pointer 9 to make the pointer 9 shine.

In the conventional light guide plate 11, the light introducing section 1
A part of the light (for example, the light having the optical path B) reflected by the back surface of the central portion 12 out of the light introduced from 3 is directly reflected from the opening 8 a without being reflected by the cutout 5. At the same time, some of the pointers 9 were not introduced into the base 9a. However, according to the light guide plate 1 of the embodiment of the present invention, the light path changes due to reflection at the portion formed on the concave surface 2a (for example, the optical path B ′).
) Is converged and guided to the notch 5. For this reason, the light introduced into the light guide plate 1 can be efficiently guided to the pointer 9, and the pointer 9 can have high brightness without increasing the light amount of the light source.

[0013]

As described above, according to the present invention,
By changing the shape of the back surface of the light guide plate, light introduced from the light source can be efficiently guided to the pointer, and the pointer can be brightened.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a light guide plate for illuminating a pointer of an instrument according to an embodiment of the present invention is attached to the back of a dial.

FIG. 2 is a plan view of a light guide plate for illuminating a pointer of a conventional instrument.

FIG. 3 is a cross-sectional view of a conventional instrument in which a light guide plate for illuminating a pointer is attached to the back of a dial.

4A and 4B are diagrams illustrating a light guide plate for illuminating a pointer of another conventional instrument, wherein FIG. 4A is a bottom view of the light guide plate 31, FIG.
(C) is a plan view, and (d) is a cross-sectional view.

5 is a partially enlarged view of a light guide plate for illuminating a pointer of the instrument shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-guide plate 2 Central part 2a Concave surface 3 Light introduction part 5 Notch

Claims (1)

(57) [Claims] 1. A light guide plate for illuminating a pointer of an instrument, which illuminates a pointer of the instrument, comprising: a light introducing portion disposed to face a light source; A central portion that reflects light introduced from the light introducing portion at the interface while propagating through the central portion; an emission surface formed on the surface of the central portion; and an emission surface formed at the central portion, the inside of the central portion. A reflection surface for guiding the light to the pointer via the emission surface by reflecting the propagated light toward the emission surface, wherein the emission surface is not reflected by the reflection surface. with reducing the light emitted from, comprising a rear portion formed a concave having <br/> cross section constant radius for converging the optical path of the light when guiding the light to the reflecting surface Light guide plate for indicator light of meter