JPH1054902A - Flat light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat light guide plate capable of uniformely illuminating an instrument dial plate without performing dimmer printing and suitable for making the instrument thin. SOLUTION: In a flat light guide plate 13, a hole part 14 for providing an illuminating light beam in the direction of its thickness, an incident plane 19 for converting a radial illuminating light beam P4 transmitted from an illuminating light source 12 provided in the hole part 14 to a parallel light beam Q1 and for making it propagate is formed on the peripheral wall of the hole part 14. An annular reflection surface 22 for reflecting the parallel light beam Q1 to the front surface side 13a is formed on the back surface side 13b in the direction of the thickness, in a step-like manner referring to the direction of thickness and in a concentric manner referring to the hole part 14 and a Fresnel lens 23 is formed concentrically about the hole part 14 for deflecting the reflected light beam Q2 reflected by the annular reflection surface 22 on the front surface side 3a so as to transmit the beam normal to the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indicator with an illuminating device, and more particularly to a flat light guide panel suitable for thinning an indicator with an illuminating device for an automobile.

[0002]

2. Description of the Related Art Conventionally, there has been known an indicating instrument for a vehicle, such as a speedometer, a tachometer, a fuel gauge, a water temperature gauge, which illuminates an instrument dial from the back of the instrument dial and illuminates a pointer. ing. FIG. 1 is a schematic view of an indicating instrument with a lighting device. In FIG. 1, 1 is a housing, 2 is a movement, 3 is an instrument dial, 4 is a pointer, 5 and 6 are bulbs as illumination light sources, 7 Reference numeral 8 denotes a light guide member, and reference numeral 9 denotes a rotation support shaft for indicating a pointer. Part of the illumination light emitted from the bulbs 5 and 6 propagates through the light guide members 7 and 8 as shown by the arrow P1, is guided to the pointer 4, and illuminates the pointer 4. The remaining illumination light emitted from the bulbs 5 and 6 directly illuminates the instrument dial 3 from the back as shown by the arrow P2 and is irregularly reflected on the inner wall surface of the housing 1 as shown by the arrow P3. To illuminate the instrument dial 3 indirectly.

[0003] In this conventional indicator with an illuminating device, the instrument dial 3 is directly illuminated by illumination light from the bulbs 5 and 6.
Alternatively, since the light is indirectly illuminated, the light guide path of the illumination light to the instrument dial 3 is complicated, and it is difficult to uniformly illuminate the instrument dial 3. There is a disadvantage that the instrument dial 3 cannot be seen with uniform brightness.

Therefore, in this type of indicating instrument with an illuminating device, the meter has uniform brightness at a place where the amount of illumination light reaching the back of the instrument dial 3 is large and at a place where the quantity of illumination light reaching the back is small. Dimming printing is performed by a method such as a mesh screen so that the dial 3 can be seen (for example,
JP-B-53-2065).

[0005]

However, in this conventional indicating instrument with an illuminating device, the specifications such as the size of the instrument dial 3 and the arrangement positions of the valves 5 and 6 are different for each type of car. Each time, there is a problem that light control printing by a method such as a mesh screen must be performed by trial and error, and it is difficult to share the light guide members 7 and 8 for each vehicle type. Also, today, with the advance of computerization, various electronic devices such as monitors for navigators are mounted on the instrument panel of vehicles, and the installation space for indicator instruments with lighting devices is limited. There is also a demand for a reduction in thickness.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to uniformly illuminate an instrument dial without performing dimming printing and to reduce the thickness. It is another object of the present invention to provide a flat light guide board suitable for the above.

[0007]

According to the first aspect of the present invention, there is provided a flat light guide panel, wherein a hole for installing an illumination light source is formed in a thickness direction, and light is emitted from the illumination light source installed in the hole. An incident surface for converting the radial luminous flux into a parallel luminous flux and transmitting the parallel luminous flux is formed on the peripheral wall of the hole, and an annular reflecting surface for reflecting the parallel luminous flux toward the front surface side has a step in the thickness direction on the rear surface side in the thickness direction. And concentrically formed with respect to the hole,
A Fresnel lens that deflects the reflected light beam so as to emit the reflected light beam reflected by the reflecting surface perpendicular to the surface is formed concentrically around the hole in the thickness direction surface side. The Fresnel lens preferably comprises a ring-shaped Fresnel lens body group having a positive angle and a ring-shaped Fresnel lens body group having a negative angle with the center of the hole as the coordinate origin. The thickness in the thickness direction of the annular reflecting surface formed in a step shape becomes larger as the distance from the illumination light source increases in order to equalize the amount of illumination light on the side closer to the illumination light source and on the side farther from the illumination light source. It is characterized by being.

The flat light guide panel is provided with an instrument display panel illuminated by a reflected light beam on the surface side in the thickness direction, and the hole is located at a position eccentric from an insertion hole through which the pivot shaft of the pointer passes. It may be formed. A reflection surface that reflects a part of the parallel light beam toward the pointer is formed near the insertion hole.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 2, reference numeral 10 denotes a housing of an indicating instrument with a lighting device. In the housing 10, a movement member 11, a bulb 12 as an illumination light source, and a flat light guide board 13 are provided. Symbol 12 '
Indicates a mounting portion for mounting the valve 12. As shown in FIGS. 2 and 3, the flat light guide panel 13 has a valve mounting hole 14 and an insertion hole 15 that extend through the thickness direction. The hole 14 is the insertion hole 1
5 is provided at a position eccentric with respect to 5. The movement member 11 is provided with a rotation support shaft 16, which penetrates the insertion hole 15 and protrudes upward, and a pointer 17 is provided at an upper end of the rotation support shaft 16. .

An instrument dial 18 is provided on the surface 13a in the thickness direction of the flat light guide panel 13. The instrument dial 18 is, for example, a speedometer, and has a surface
Characters and the like indicating the scale and speed are printed. The peripheral wall of the hole 14 is an annular incident surface 19 on which the illumination light P4 from the bulb 12 is incident. Reference numeral 20 denotes a light emission center of the bulb 12. Here, the cross section in the thickness direction of the annular incident surface 19 is a hyperboloid, but the present invention is not limited to this. The annular incident surface 19 plays a role of converting a radial illumination light beam P4 into a parallel light beam Q1 with respect to a cross section in a thickness direction emitted from the bulb 12, and propagating the light beam through the flat light guide board 13.

On the rear side 13b in the thickness direction of the flat light guide panel 13, an annular step portion 2 is formed stepwise in the thickness direction and concentric with the hole 14 as shown in an enlarged view in FIG.
1 is formed. This annular staircase 21 has a parallel light flux Q
1 has an annular reflection curved surface 22 that totally reflects the light toward the surface side 13a in the thickness direction. On the surface 13a in the thickness direction of the flat light guide panel 13, a Fresnel lens 23 (see FIG. 5) that deflects the reflected light Q2 so that the reflected light Q2 reflected by the annular reflecting curved surface 22 is emitted perpendicular to the surface. )
Are formed concentrically with the hole 14 as a center. As shown in FIG. 5, the Fresnel lens 23 has a positive refraction angle α with the light emission center 20 of the hole 14 as the coordinate origin.
It is desirable to include the annular Fresnel lens element group 23a having the following formula and the annular Fresnel lens element group 23b having the negative refraction angle β in order to emit the reflected light Q2 perpendicular to the surface 13a.

For example, ten Fresnel lenses 23 are formed for each one annular step portion 21. Illumination ranges Xi-1, Xi, Xi + 1 (integers from i = 1 to n) of a unit area illuminated by the reflected light flux Q2 reflected by each annular reflection curved surface 22 are made substantially equal as shown in FIG. Lens 2 corresponding to each annular reflection curved surface 22
The focus of 3 is, as shown in FIG.
2 reflected light beam Q2 of the parallel light beam Q1 incident on the lower end 22a
Of the parallel light beam Q1 incident on the upper end 22b of the annular reflection curved surface 22 and the virtual line q1 extending the reflection direction to the opposite side.
A virtual line q2 extending the reflection direction of the light beam 2 to the opposite side and the lower end 2
An imaginary line q3, which extends the reflection direction of the reflected light beam Q2 of the parallel light beam Q1 incident on the point 22c between the upper end 22a and the upper end 22b, is present in the most integrated region. The illumination light beam P4 emitted from the bulb 12 is converted into a parallel light beam Q1 in the cross section in the thickness direction, but the illumination light beam P4 is still radial in a plane orthogonal to the cross section in the thickness direction, as shown in FIG. The illumination light beam P4 is propagated inside the flat light guide panel 13 and reaches the respective annular reflection curved surfaces 22. Since the radial illumination light beam P4 diffuses in proportion to the square of the distance,
Compared to the amount of illumination light on the side closer to the bulb 12, the bulb 12
The amount of illumination light on the side farther from the camera is greatly attenuated. Therefore, the flat light guide panel 13 is designed such that the thickness H of the annular reflection curved surface 22 increases as the distance from the bulb 12 increases, so that the amount of illumination light per unit area is substantially the same. (See FIG. 6). Thereby, the reflection area increases as the annular reflection curved surface 22 moves away from the bulb 12, so that the light quantity of the illumination light near the bulb 12 and the light quantity of the illumination light far from the bulb 12 are made substantially the same. be able to.

FIG. 2 shows the flat light guide panel 13.
As shown in FIG. 3, a reflection groove 24 having a total reflection surface is formed near the insertion hole 16 so as to totally reflect a part of the parallel light beam Q <b> 1 in the vertical direction toward the pointer 17. In FIG. 2, the code Q2 is propagated through the pointer 17 to
Shows light rays emitted to the outside after illuminating. Therefore, the bulb 12 serves to illuminate the hands 17 and the instrument dial 18, and the bulb 12 is used for both illumination of the hands 17 and illumination of the instrument dial 18.

As shown in FIG. 3, a liquid crystal display panel LCD is provided in an unused area of the instrument dial 18 on the side opposite to the hole 14 of the flat light guide panel 13 with the insertion hole 15 interposed therebetween. A notch 25 is provided. As shown in FIG. 7, the inclined peripheral wall 26 forming the notch 25 is a reflecting surface that totally reflects the reflected light beam P5 ′ propagating inside the flat guide light board 13 downward in the thickness direction. . The flat light guide plate 13 has a V-shaped reflection surface portion 27 formed on the periphery thereof, and the V-shaped reflection surface portion 27 reflects a parallel light beam P5 propagating inside the flat guide plate 13 toward the inclined peripheral wall 26. Play a role.

As shown in FIG. 7, an inclined peripheral wall 28 is provided below the inclined peripheral wall 26 so as to face the reflecting surface 30 formed on the liquid crystal holder 29 so that the reflected light beam P5 'is directed toward the reflecting surface 30 formed on the liquid crystal holder 29. The liquid crystal display panel LCD plays a role of reflecting light, and the reflected light beam P5 reflected by the reflection surface 30 of the liquid crystal display panel LCD.
'Illuminated. The liquid crystal display panel LCD is used, for example, as an odd trip meter.

Since the amount of illumination light emitted from the bulb 12 and going upward is generally different from the amount of illumination light emitted from the bulb 12 and going downward, illumination unevenness of the illumination light based on this is reduced. This may occur, but this can be solved by appropriately devising the reflection area of the annular reflection curved surface 22 and the interval between the annular steps.

[0017]

According to the present invention, as described above, the illumination light source is arranged in the hole of the flat light guide panel. Therefore, when this flat light guide panel is applied to an indicator with a lighting device, The indicator instrument with the lighting device can be made thinner.

Further, since the instrument dial can be uniformly illuminated vertically by the flat light guide panel, the instrument dial can be viewed with uniform brightness without performing dimming printing on the instrument dial. This has the effect.

Further, since the arrangement of the illumination light source is fixed with respect to the flat light guide panel, it is easy to share the indicating instrument with the illumination device for each vehicle type.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a conventional indicator with a lighting device provided with a light guide member.

FIG. 2 is a cross-sectional view schematically showing an example of an indicator with a lighting device to which the flat light guide panel according to the present invention is applied.

FIG. 3 is a plan view of a flat light guide panel according to the present invention.

FIG. 4 is a partial cross-sectional view showing a part of a flat light guide panel according to the present invention in an enlarged manner.

5A and 5B are explanatory views of a flat light guide panel according to the present invention, wherein FIG. 5A is a partially enlarged view showing a part of a circular frame indicated by a broken line in FIG. It is a schematic diagram for demonstrating the effect | action of the flat light guide board concerned.

FIG. 6 is a partially enlarged cross-sectional view showing the annular step portion shown in FIG. 4 in a further enlarged manner.

FIG. 7 is a partial cross-sectional view for explaining light guide of an illumination light beam to a liquid crystal display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Illumination light source 13 ... Flat light guide board 14 ... Hole 19 ... Incident surface 13a ... Front side 13b ... Back side 22 ... Annular reflection surface 23 ... Fresnel lens P4 ... Illumination light beam Q1 ... Parallel light beam Q2 ... Reflected light beam

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kazuo Arai 2-1910 Nisshincho, Omiya City, Saitama Prefecture Kansei Corporation (72) Inventor Tetsuhide Takeyama 5-9-11, Minami-Nagasaki, Toshima-ku, Tokyo (72) Inventor Toshihisa Higuchi 5-9-1, Minami-Nagasaki, Toshima-ku, Tokyo Inside Fujii Kogaku

Claims (6)

[Claims] 1. An illumination light source installation hole is formed in a thickness direction, and an incident surface for converting a radial light beam emitted from an illumination light source installed in the hole light beam into a parallel light beam and transmitting the parallel light beam is formed in the hole portion. An annular reflecting surface formed on the peripheral wall and reflecting the parallel light beam toward the front surface side is formed stepwise in the thickness direction on the rear side in the thickness direction and concentrically about the hole, and on the thickness direction front surface side. A flat light guide plate, wherein a Fresnel lens for deflecting the reflected light beam so as to emit the reflected light beam reflected by the reflecting surface perpendicular to the surface is formed concentrically with the hole as a center. 2. In order to equalize the amount of illumination light on the side closer to the illumination light source and on the side farther from the illumination light source, the width in the thickness direction of the annular reflection surface formed in a step shape is equal to the illumination light source. 2. The flat light guide board according to claim 1, wherein the size of the flat light guide board increases as the distance from the light source increases. 3. The flat light guide panel according to claim 1, wherein an instrument display panel illuminated by the reflected light beam is provided on the surface side in the thickness direction. 4. The flat light guide panel according to claim 3, wherein said hole is formed at a position eccentric with respect to an insertion hole through which a rotation support shaft of the pointer penetrates. 5. The Fresnel lens element group according to claim 1, wherein the Fresnel lens element includes a ring-shaped Fresnel lens element group having a positive angle and a ring-shaped annular Fresnel lens element group having the center of the hole as a coordinate origin. The described flat light guide panel. 6. The flat light guide panel according to claim 4, wherein a reflection surface for reflecting a part of the parallel light beam toward the pointer is formed near the insertion hole.