JPH09198908A - Surface luminescence lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve luminous efficacy by arranging light sources along the edge sections of a specific surface region on the upper face of a light guide plate made of a transparent or semitransparent resin, and forming slits along the edge sections. SOLUTION: Light source devices 30, 30 are arranged on the outside along two short sides Sa, Sa of the display region S of a light guide plate 20, and through hole-like slits 22, 22 are formed along two long sides Sb, Sb of the display region S. When the light source devices 30 are lighted, the light emitted from LEDs is radiated toward the inside of the display region S in the light guide plate 20, the total reflection of the light is repeated at the boundary between the surface and the back face of the light guide plate 20, and the surface of the light guide plate 20 luminesces. A part of the light proceeding in the light guide plate 20 is reflected at the inner wall boundaries of the slits 22, and the luminous efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention illuminates a planar display device which does not emit light by itself, such as a liquid crystal panel display device, by illuminating the planar display device from behind so-called backlight. Called a surface emitting lighting device.

[0002]

2. Description of the Related Art As an example of this type of surface emitting lighting device,
For example, there is one disclosed in Japanese Utility Model Publication No. 4-14943. The surface emitting lighting device disclosed in the publication is formed by forming a recess on the upper surface of the peripheral edge of a transparent or semi-transparent light guide plate having a certain thickness, and fitting the light source device into the recess. In the light source device, an LED chip is arranged on the bottom of a bottomed box-shaped reflection case having an opening on the front surface, and the inside of the case is filled with a transparent resin to form a light emitting portion, and a lead terminal is extended from this light emitting portion. It is a thing. The light emitted by the light source device is reflected by the inner surface of the reflection case and is irradiated to the inside of the light guide plate, and the light thus irradiated is repeatedly totally reflected at the boundary between the front surface and the back surface of the light guide plate and is distributed over the entire area of the light guide plate. And, at some point, the light is emitted from the surface of the light guide plate to the outside. As a result, even though the light guide plate has a certain area and the light source device is partially arranged at the edge of the light guide plate, the entire surface of the light guide plate seems to be shining.

[0003]

In the surface emitting illuminating device disclosed in the above publication, the light guide plate has a planar shape of a size substantially corresponding to the display area of the display device to be illuminated, and the light guide plate is almost vertically and horizontally. It has a symmetrical shape. Therefore, it is relatively easy to make the entire surface of the light guide plate illuminate equally.

By the way, there is a case where the light guide plate of this type of surface emitting illuminating device is constructed so that the planar display device to be illuminated can be placed in a positioning manner. In this case, the external shape of the planar display device is usually larger than its display area,
Moreover, the drive circuit may be attached integrally. When the light guide plate is formed so that such a planar display device can be held on the upper surface, its outer shape must be larger than the display area of the display device.

When such a light guide plate is integrally formed of transparent or translucent resin, light emitted from the light source is spread to the entire light guide plate other than the display area of the display device without any care. If the planar shape of this light guide plate has to be asymmetrical vertically and horizontally because it is necessary to mount the planar display device, the light from the light source will reach the entire area of the light guide plate as described above. As a result of the surface emitting light over time, there is a problem that the amount of light in a region corresponding to the display portion of the planar display device, which originally requires illumination, is reduced, or the brightness is uneven in the region.

As a method for making the brightness on the front surface of this type of light guide plate uniform, the reflection film formed on the back surface of the light guide plate is formed into, for example, dots having different densities to reflect light on the back surface of the light guide plate. There is a method in which the amount is made different at each part of the planar area of the light guide plate. However, as described above, in the case where the light guide plate is irregularly enlarged beyond the display area, it is practically appropriate to take the above-mentioned method so as to make the light amount in a predetermined area constant. It's extremely difficult.

The invention of the present application was conceived under such circumstances, and it seems that the planar shape of the light guide plate is enlarged to a strange shape beyond the display area of the display device to be illuminated. Even in such a case, a surface-emitting lighting device is provided which ensures a sufficient amount of light emission in a limited area corresponding to the display section and can easily achieve uniform light emission in such an area. The task is to do.

[0008]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

That is, the surface emitting lighting device of the present invention is
In a surface emitting lighting device comprising a light guide plate formed of a transparent or translucent resin, and a light source arranged along an edge of a predetermined planar area set on the upper surface of the light guide plate, the light guide plate comprises: Are characterized in that a slit is formed which extends along a selected range of the edge of the region and reflects the light from the light source into the region.

The predetermined planar area is an area corresponding to a display area of a liquid crystal panel display device or the like which is an illumination target of the surface emitting illumination device. For example, when the display area is an oblong area, the light source is arranged along the short side of the area, and the slit is formed along the long side of the area. The light emitted from the light source reaches the entire area of the light guide plate by repeating total reflection at the boundary between the front surface and the back surface of the light guide plate, but since the light is reflected by the inner wall of the slit, the light is emitted from the slit. Is not diffused into the remaining area of the light guide plate.

Therefore, even if the surface-emitting lighting device of the present invention is enlarged to have an outer shape larger than the size of the display unit to be illuminated, the light emitted from the light source is to be illuminated. The light emitted from the light source can be emitted only within a limited area within the light guide plate without being unnecessarily diffused beyond a certain display area, so that the luminous efficiency can be improved and the above area can be improved. It becomes easy to make the light uniformly emitted.

Further, since the slits can be formed at the same time when the light guide plate is resin-molded, the number of steps for manufacturing the light guide plate does not increase, and the cost increases in implementing the present invention. No more.

In a preferred embodiment, the light source is arranged inside the outer edge of the light guide plate and within the thickness range of the light guide plate. As a result of such a configuration, it becomes possible to freely select the area of the light guide plate and to make it efficiently emit light.

In a preferred embodiment, the light guide plate is integrally formed with a holding means for positioning and holding the panel type display device on the upper surface thereof.

With this configuration, the mutual relationship between the panel-type display device to be illuminated and the surface-emitting lighting device of the present invention can be regulated to a constant level, and the display quality of the panel-type display device can be improved. Further, since another member for supporting the panel type display device is unnecessary, it is possible to reduce the number of parts of an electronic device in which the panel type display device with the surface emitting lighting device of this type is incorporated.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the drawings.

[0017]

1 is a plan view of an embodiment of a surface emitting lighting device 10 according to the present invention, and FIG. 2 is a line II- of FIG.
A sectional view taken along line II and FIG. 3 are sectional views taken along line III-III in FIG.

As shown in FIG. 1, the surface emitting lighting device 10 is constructed so that a planar display device D (FIG. 2) such as a liquid crystal panel display device, which is a display object, can be held on the upper surface in a positioned state. It was done. The light guide plate 20 having a predetermined thickness formed of a transparent or translucent resin has an oblong rectangular planar shape having a size corresponding to the outer shape of the display device D, and the display device has four corners on its upper surface. L-shaped holding protrusions 21 for restraining and holding the four corners of D are formed. In this type of display device D, an area smaller than its outer shape is a display area, and the display area S is shown by a virtual line in FIG. That is, the display area S is an area having a rectangular shape smaller than the outer shape of the light guide plate 20.

The light guide plate 20 in this embodiment is arranged along the two short sides Sa, Sa of the display area S,
The light source devices 30 and 30 are arranged on the outer side thereof, while through-hole slits 22 and 22 are formed along the two long sides Sb and Sb of the display region S.

As the light source device 30, in the present embodiment, as shown in FIGS. 4 and 5, an LED chip 32 as a light source is arranged on the inner bottom surface of a box-shaped reflection case 31 having an opening on the front side, and the case 31 is arranged. The inside of the is filled with the transparent resin 33 to form the light emitting portion 34, and
The lead terminal 35 is extended from below the light emitting portion 34. Correspondingly, a concave portion 23 is formed in the light guide plate 20 so that the box-shaped reflection case 31 is fitted from above, and each lead terminal 35 is provided on the bottom wall of the concave portion 23. A through hole 24 is formed so as to extend downward.

In the present embodiment, the light source device 30 has a vertical height slightly smaller than the thickness dimension of the light guide plate 20 as shown in FIG. A reflection case 31 having a length corresponding to the length of the short side Sa is used. This reflective case 3
At the bottom of 1, there are three conductor plates 36a,
36b and 36c are arranged, and the LED chip 3 is provided at the edge of two adjacent conductor plates 36b and 36c.
2,32 are bonded and these LE
The D chips 32, 32 and the adjacent conductor plates are connected by wire bonding. That is, in this embodiment, the two LED chips 32 are arranged in series inside the reflection case 31. Of the three conductor plates 36a, 36b, 36c, the lead terminals 35 are integrally extended from the conductors 36a, 36c arranged at both ends.

As is clear from the above, the light guide plate 20 is
Is a recessed portion 23 for fitting the light emitting portion 34 of the light source device into a plate-shaped portion having a predetermined thickness, and a penetrating slit 22.
And the display device holding projection 21 are formed, and can be easily obtained by resin integral molding using a transparent or translucent resin. As a material of the light guide plate 20,
For example, acrylic resin, epoxy resin, or polycarbonate is preferably used.

In the above structure, when the light source device 30 is turned on, the light emitted from the LED chip 32 is reflected by the reflective case 3.
The light is emitted from the first opening toward the inside of the display area S inside the light guide plate 20. The light thus radiated repeats total reflection at the boundary between the front surface and the back surface of the light guide plate 20, and causes the surface of the light guide plate 20 to emit light over the entire display area. Then, as shown in FIG.
Since a part of the light traveling in the inside of the slit is reflected by the inner wall boundary of the slit 22, the light emitted from the light source is prevented from being unnecessarily diffused to the remaining portion of the light guide plate other than the display area S. In this way, the light emitted from the light source device 30 arranged along the short side of the display area conducts through the light guide plate 20 within a limited range, that is, within the area S, and causes the surface thereof to emit light. .

As shown in FIG. 3, the light guide plate 2
In some cases, a suitable reflection sheet 25 is provided on the lower surface of 0 to prevent the light emitted from the light source device 30 from unnecessarily leaking from the bottom surface of the light guide plate 20 to the outside, thereby improving the luminous efficiency. Further, the reflective sheet 25 is formed of opaque dots, and the dot density is varied depending on each part of the planar area of the light guide plate, whereby the display area S of the light guide plate 20 is formed.
May be made to emit light evenly.

Of course, the scope of the present invention is not limited to the above embodiment. The planar shape of the light guide plate is variously changed according to the outer shape of the display device to be held thereon. Further, the form of the light source to be arranged inside the light guide plate is not limited to the one having the elongated reflection case as in the embodiment shown in the figure, and may be a point light source.
In this case, it is desirable that slits be formed between the point light sources.

Further, in the embodiment shown in the drawings, the slit 22 is a long slit corresponding to the long side length of the display area, but slits of shorter length are arranged in parallel. Good. If you do this,
It is possible to prevent the surface rigidity of the light guide plate from being lowered by the slit. Further, although the slit 22 is formed in a penetrating shape in the embodiment shown in the drawings, it may be formed in a concave groove shape with the bottom wall left. In this case, it is possible to suppress a decrease in surface rigidity of the light guide plate.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a surface emitting lighting device of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a cross-sectional view of a light emitting unit.

FIG. 5 is a front view of a light emitting device.

[Explanation of symbols]

 10 Surface-Emitting Illumination Device 20 Light Guide Plate 21 Holding Protrusion 22 Slit 30 Light Source Device 31 Box-shaped Reflecting Case 32 LED Chip

Claims (3)

[Claims] 1. A surface emitting lighting device comprising a light guide plate formed of a transparent or translucent resin and a light source arranged along an edge of a predetermined planar area set on the upper surface of the light guide plate. The surface of the surface of the light guide plate is characterized in that a slit is formed in the light guide plate to extend along a selected range of an edge portion of the area to reflect light from the light source into the area. Lighting equipment. 2. The surface-emitting lighting device according to claim 1, wherein the light source is arranged inside the outer edge of the light guide plate and within the thickness range of the light guide plate. 3. The surface emitting lighting device according to claim 1, wherein a holding means for positioning and holding the panel type display device is integrally formed on the upper surface of the light guide plate.