JPS60129779A - Photoconductive lighting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a light guiding type illumination device that efficiently transmits light from a light source.

(Prior Art) A light guide type illumination device includes a light source and a light guide made of a transparent or anti-transparent member that transmits light from the light source by transmission and reflection. This light-guiding lighting device is applied, for example, to motorcycles, as nighttime lighting for liquid crystal display devices that display running speed and time, or as surface display devices for warning displays that notify of abnormalities occurring in various parts of hydraulic circuits, etc. Ru. For example, in a liquid crystal display device, as disclosed in Japanese Unexamined Patent Publication No. 57-78081, a light guide is disposed between a liquid crystal display unit and a printed circuit board provided with a display circuit of the liquid crystal display unit. A light source is disposed at the end of the light guide, and light from the light source is introduced into the light guide and guided to the back surface of the liquid crystal display unit to display a predetermined display.

This light guide l is formed into a plate or rod shape as shown in FIG. located close together. The light from this light source 3 enters the light guide portion l in a radial manner and travels straight as it is. Some of this light is projected at an angle of projection to the interface 4 between the light guide l and air that is less than the critical angle for total reflection, and this light is refracted without being totally reflected at the interface 4, and the light guide 1 will leak into the air.

For this reason, Publication of Utility Model Publication No. 43-11410 and Publication of Utility Model Publication No. 44
As shown in Publication No. 29830, a reflective plate made of aluminum or the like is provided from the outside to sandwich the light guide in the area where the light inside the light guide is not totally reflected at the interface with the air. It's reflecting. By the way, it takes time and effort to attach this reflector, and the manufacturing cost is high. Furthermore, since the light propagates by being reflected within the light guide, the distance between the illumination unit and the light source becomes long, which increases the attenuation of the light and causes problems such as poor lighting effects.

(Object of the Invention) This invention was made against the background of the above circumstances, and has a simple structure in which light from a light source is refracted by the curved surface of the light receiving part at the end of the light guide, thereby directing the light to the light guide. It is an object of the present invention to provide a light guiding type illumination device that converges light in the longitudinal direction and guides it into a light guiding body to improve irradiation efficiency.

(Structure of the Invention) In order to achieve the above object, the present invention makes the end of the light guide facing the light source a light receiving part having a convex curved surface,
It is characterized in that the light from the light source is refracted by this curved surface and converged in the longitudinal direction of the light guide.

(Example) Hereinafter, an example in which the present invention is applied to a motorcycle will be described in detail based on male drawings.

2 and 4 are applied to a liquid crystal display device, in which a substantially square window 12 is opened in the center of a synthetic resin meter case 11, and rectangular windows 13 on the left and right sides of the meter case 11 are shown.
14 is open.

A liquid crystal display device A is built into the meter case 11, and the liquid crystal display device A displays a speed display 15 on a window portion 12, and a time display 16 and a fuel display 17 from a window portion 14.

A speed warning light 18, a high beam indicator light 19, an oil warning light 20, and a starting lamp 21 are provided within the right window portion 13.

As shown in FIG. 3, the liquid crystal display device A is composed of a liquid crystal display unit B, a light guiding type illumination device C, and a printed circuit board.

The liquid crystal display unit) B is composed of a display plate 22 containing a liquid crystal and a semi-transmissive reflecting plate 23 provided on the back surface of the display plate 22. The display board 22 is used for bar display of the running speed display 15 and time display 16, and for analog display of fuel table>1<17. The liquid crystal display unit (B) is held in the meter case 11 via a spacer holder 24.

A reflecting plate 24 arranged on the back surface of the display board 22 reflects light hitting the front surface and transmits light from the back surface.

The light guiding type illumination device C guides the light and displays the liquid crystal display)
B is illuminated from the back side, and the light guide 25 and light source 26
It is composed of. The light guide 25 is formed into a plate shape from transparent or semi-transparent synthetic resin through which light can pass. A large number of small recesses 27 are engraved on the back surface of the light guide 25, corresponding to the portions of the liquid crystal display unit B to which letters, numbers, etc. are attached. As shown in FIG. 3, this small recess 27 reflects the light dispersed over the entire area of the light guide 25 and changes its direction toward the liquid crystal display unit (H), thereby uniformly illuminating the liquid crystal display unit B.

The end of the light guide 25 serves as a light receiving section 25a. The light receiving portion 25a has a convex shape toward the light source 16, and its end surface is entirely curved into a curved surface 15b. Hikari KA26
The light enters the curved surface 25b at a deep angle and easily exceeds the critical angle at which the light is totally reflected. Therefore, the light is refracted and converged by the curved surface 25b as a reaction, and the light introduced into the light guide 25 travels straight in the longitudinal direction and is transmitted.

This light source 26 has a curved surface 25b of the light guide 25 as a spherical surface, and when placed near its focal point, the light beam that is refracted and converged becomes approximately parallel within the light guide 25 and is transmitted most efficiently.

The printed circuit board includes a display circuit of the liquid crystal display unit B, and is provided below the light guide 25 with a predetermined gap 28 in between. A lead wire is passed through this gap 28. The printed circuit board is fixed to the meter case l, and holds the light guide 25 between it and the liquid crystal display unit l-B. The display circuit on the printed circuit board connects connector 2 to LCD display unit B.
9 is connected.

Next, the operation of this embodiment will be explained. When the liquid crystal display device A is bright during the daytime, the sunlight that has passed through the display plate 22 of the liquid crystal display unit H is reflected on the reflector plate 24.
The reflected light illuminates the liquid crystal in the display panel 22 to display a predetermined display.

On the other hand, at night, when the light source 26 is turned on, the light hits the back surface of the liquid crystal display unit B through the light guide 25.
A predetermined display is made by illuminating the liquid crystal in the display board 22.

At this time, the light receiving portion 25a of the light guide 25 is formed in a convex shape toward the light source 26, and furthermore, the end portion is formed into a curved surface 25b over the entire surface up to both sides. Therefore, the light source 26
The direct light reaches both ends of this end, and the closer it goes to both sides, the more it enters the curved surface 25b at a deeper angle and becomes more likely to exceed the critical angle. As a result, the curved surface 25b functions as a convex lens, and the light is refracted and converged, and transmitted in the longitudinal direction within the light guide 25. Since this light ray travels straight through the light guide 25 without being directed toward both sides of the light guide 25, the distance from the light source 26 can be minimized and illumination efficiency can be improved.

FIG. 5 shows another embodiment, in which a convex curved surface 25b is partially formed on a light receiving section 25a provided at the end of the light guide 25. FIG. The light from the light source 26 illuminates each curved surface 2.
5b and is converged in the longitudinal direction and transmitted in the longitudinal direction of the light guide 25. This achieves the same effect as a convex lens by partially combining convex surfaces.

Although the above embodiment was applied to a liquid crystal display device, small recesses are engraved on the back surface of the light guide to display letters, numbers, etc. The present invention can also be applied to a planar display device with stipple display that reflects this light in small recesses and displays predetermined characters, numbers, etc.

(Effects of the Invention) As described above, the present invention uses the end of the light guide facing the light source as a light receiving part, and the convex curved surface of this light receiving part refracts the light from the light source. Since the light guide is converged in the same direction, the light introduced into the light guide does not need to be attached to the side of the light guide as in the conventional case, and the structure is simple, allowing the light to exit from the light guide. This can be prevented. The light roughly introduced into the light guide is less likely to be reflected and travel inside the light guide, which shortens the distance between the illumination section and the light source, allowing effective use of the light from the light source and improving lighting efficiency. It is possible to suppress heat generation by reducing the value of I'T.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional light guiding type illumination device, and FIGS. 2 to 5 show an embodiment in which the present invention is applied to a liquid crystal display device. FIG. 2 is a plan view, and FIG. Figure 2 c7) m-m
4(a) and 4(b) are enlarged views of essential parts of the present invention, FIG. 4(a) is a plan view, and FIG. 4(b) is a sectional view.
FIG. 5 is a plan view showing another embodiment. A...Liquid crystal display device B...Liquid crystal display unit C.
...Light guiding type lighting device D...Printed circuit board 15...
Light guide 15a...End portion 15b...Curved surface 16...Light source 17...Small recess Fig. 1 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] In a four-light illumination device comprising a light source and a plate-shaped or rod-shaped light guide that transmits light from the light source by transmission and reflection, the end of the light guide facing the light source is formed into a convex shape. A light guide type illumination device having a light receiving part having a curved surface, and the light from the light source is refracted by the curved surface and converged in the longitudinal direction of the light guide.