JP2010044900A - Backlight device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a backlight device to be bright with a light volume further increased than before, and to be applied to a large advertizing or a signboard. <P>SOLUTION: The backlight device 1 using light guide plates 11, 12 as transparent or semi-transparent optical media with irregular reflection parts 21a, b formed on the surface, respectively, is so structured that the plurality of light guide plates 11, 12, superposed on each other, irradiate illuminating light from the surface through their respective light source devices 13a, b arranged at their end faces, and illuminating light irradiated from the surface of each light guide plate is added. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a backlight device used as a backlight for advertisements, signboards, display devices, and the like.

  Conventionally, a backlight device is used for a liquid crystal panel or the like used as a display device of a personal computer or a television receiver.

  As a backlight device, a backlight device using a light guide plate which is a transparent or semi-transparent optical medium and has an irregular reflection portion formed on the surface thereof is often used (Patent Document 1). A backlight device using a light guide plate greatly contributes to a reduction in thickness or size of a product.

In addition, a backlight device using an LED (light emitting diode) as a light source of the light guide plate has low power consumption, has a long life, has durability, and is now widely used as a stable backlight device.
JP-A-6-118247

  However, in the backlight device using the conventional light guide plate, it is excellent for small devices such as mobile phones, personal computers, small liquid crystal televisions, etc., but for large items such as advertisements and billboards, The amount of light was sometimes insufficient.

  For example, in a rectangular advertising tower having a side of about 1 meter to several meters, a sufficient brightness may not be obtained with a conventional backlight device due to insufficient light quantity. This is because the amount of light per unit decreases as the area of the light guide plate increases because the light source is disposed on the end face of the light guide plate.

  The present invention has been made in view of the above-described problems, and provides a backlight device that can be brightened by increasing the amount of light compared to the conventional art and can be applied to large advertisements and billboards. With the goal.

  An apparatus according to an embodiment of the present invention is a backlight device using a light guide plate that is a transparent or translucent optical medium and has a diffused reflection portion formed on the surface thereof, and a plurality of the light guide plates are arranged to overlap each other. Each of the light guide plates emits illumination light from the surface by the light sources arranged on the end surfaces of the plurality of light guide plates, and the illumination light emitted from the surface of each light guide plate is added Has been.

  Preferably, each of the plurality of light guide plates has the irregular reflection portion formed on the back surface thereof, and the irregular reflection portion is formed on the back surface of the lowermost light guide plate of the stacked plurality of light guide plates. A white reflective layer is formed to cover the surface.

  The light source is disposed so that light is incident on each end face of the plurality of light guide plates stacked.

  Preferably, the irregular reflection portions are formed at positions shifted from each other in the plurality of the light guide plates that are overlaid.

  According to the present invention, the amount of light can be increased and brightened compared to the prior art, and the present invention can be applied to large advertisements and billboards.

  1 is a front view showing the overall appearance of a backlight device 1 according to an embodiment of the present invention, FIG. 2 is a plan view of the backlight device 1, and FIG. 3 is an enlarged view of a part of the backlight device 1 shown in FIG. 4 is a plan view of the backlight device 1 shown in FIG. 3, and FIG. 5 is a diagram showing an example of a light source.

  1 to 4, the backlight device 1 includes a first light guide plate 11, a second light guide plate 12, light source devices 13a and 13b, and the like.

  The first light guide plate 11 is a transparent or translucent optical medium KB, and has an irregular reflection portion 21a formed on the back surface thereof. The second light guide plate 12 is a transparent or translucent optical medium KB, and has an irregular reflection portion 21b formed on the back surface thereof.

  As the optical medium KB for the first light guide plate 11 and the second light guide plate 12, a synthetic resin material having good translucency such as acrylic resin is used. When light is incident from the end face of the optical medium KB, reflection is repeated inside and reaches the other end face. In the middle, incident light is irregularly reflected by the irregular reflection portions 21a and 21b, and is emitted from the respective surfaces of the first light guide plate 11 and the second light guide plate 12. As a result, the surface SF of the first light guide plate 11 is exposed to the outside. Eject.

  As described above, the backlight device 1 includes a plurality of light guide plates, in the present embodiment, the two first light guide plates 11 and the second light guide plate 12 that are stacked, and is disposed on the end surfaces of the plurality of light guide plates. The light source devices 13a and 13b are configured such that each light guide plate emits illumination light from the surface, and illumination light emitted from the surface of each light guide plate is added.

  As shown in FIG. 3 and FIG. 4, as the irregular reflection portions 21 a and b, a grid pattern (vertical grid) composed of vertical lines and horizontal lines is drawn. Each line is formed by making a cut on the surface on the back side of each optical medium KB using an appropriate blade or tool.

  The distance between the cells is rough on the side close to the end face where the light source devices 13a and 13b are located, and becomes finer as the distance increases. That is, since the intensity of light from the light source devices 13a and 13b is large at a position close to the light source devices 13a and 13b, the amount of irregular reflection is reduced, and at a distant position, the intensity of light is small and the amount of irregular reflection is increased. A uniform amount of light can be obtained over the entire surface of 1.

  As well shown in FIG. 3, the irregular reflection portions 21 a and 21 b are formed at positions shifted from each other in the two overlapped first light guide plate 11 and second light guide plate 12. That is, the grids formed on the first light guide plate 11 and the grids formed on the second light guide plate 12 are formed so as to be shifted from each other, that is, so that the line is located at an intermediate position of the partner. . However, these cells may not all pass each other, and some of them may overlap.

  Thereby, the light emitted from the second light guide plate 12 which is the lower layer can be emitted to the outside through the surface SF without being disturbed by the irregular reflection portion 21a of the first light guide plate 11 as much as possible.

  In addition, the cross-sectional shape of the line which forms the irregular reflection parts 21a and 21b can be various. Moreover, it is good also as another pattern instead of a square. Further, the irregular reflection portions 21a and 21b may be formed not by lines but by a large number of dots (dot-like concave portions). Further, the irregular reflection portions 21a and 21b may not be formed by cutting the surface of the optical medium KB, but the irregular reflection portions may be formed by other methods. For example, it is possible to use those described in Patent Document 1 described above and others.

  Further, a white reflective layer 22 that covers the irregularly reflected portion 21b is formed on the surface HF on the back surface side of the second light guide plate 12 that is the lowermost layer. The reflective layer 22 may affix a reflective sheet-like film on the surface HF. A white paint or pigment may be applied to the surface HF.

  The light source devices 13a and 13b are obtained by arranging a large number of light-emitting diodes 15, 15, 15... On a long printed circuit board 14 at appropriate intervals and mounting a drive circuit for the light-emitting diodes 15 between them. is there. Each light-emitting diode 15 is arranged so that light is incident on the respective end faces of the two stacked first light guide plates 11 and 12.

  The light emitting diode 15 is arranged so that light is incident on each end face of the light guide plate, so that the light use efficiency is good. However, a large light emitting diode is used, and the light of one light emitting diode is a plurality of light guide plates. You may arrange | position so that it may inject with respect to the end surface.

  Various types of light emitting diodes 15 can be used. For example, as shown in FIG. 5A, a light emitting diode 15a in which four light sources KG are arranged in one square package may be used. Further, as shown in FIG. 5B, a light emitting diode 15b in which six light sources KG are arranged in a row in one long package may be used.

  According to the backlight device 1 described above, since the first light guide plate 11 and the second light guide plate 12 are overlapped, the amount of light emitted from the surface SF of the backlight device 1 to the outside is one first light guide plate. Compared with the case of the one light guide plate 11, the light quantity is almost doubled, and the amount of light can be greatly increased to make it brighter. Therefore, it can be applied to large advertisements and signboards.

  Further, as the optical medium KB of the first light guide plate 11 or the second light guide plate 12, for example, a thin acrylic resin, for example, a plate having a thickness of about 5 mm can be used. The weight of the lighter. Therefore, the light guide plate can be easily manufactured, and when the backlight device 1 is transported, the plurality of light guide plates are disassembled so that the weight is light, the transport is easy, and the assembly and installation at the site is also easy.

  Also, even when a large amount of light is required, it can be adapted by increasing the number of light guide plates to be stacked, so the same standard product or general-purpose product can be used as the optical medium KB, and the manufacturing cost can be reduced. Can be achieved.

  Thus, by increasing the number of light guide plates to be overlapped by a factor of two to three, the amount of light can be increased by a factor of two to three. By forming the light guide plate in multiple layers, the incident surface of the light guide plate can be increased within a limited area and depth, and a necessary amount of light can be obtained.

  In the above-described embodiment, a fluorescent lamp, a cold cathode discharge tube, or the like can be used as the light source devices 13a and 13b. The light source devices 13a and 13b may be arranged on all end faces around the optical medium KB. The backlight device 1 may be housed in a suitable housing. The backlight device 1 can be mounted in an appropriate display device, advertising tower, signboard, or the like.

  In the embodiment described above, the structure, shape, dimensions, number, material, composition, etc. of the whole or each part can be appropriately changed in accordance with the spirit of the present invention.

It is a front view which shows the external appearance of the whole backlight apparatus of one Embodiment of this invention. It is a top view of a backlight apparatus. It is a figure which expands and shows a part of backlight apparatus shown in FIG. FIG. 4 is a plan view of the backlight device shown in FIG. 3. It is a figure which shows the example of a light source.

Explanation of symbols

1 Backlight Device 11 First Light Guide Plate (Light Guide Plate)
12 Second light guide plate (light guide plate)
13a, b Light source device (light source)
21a, b Diffuse reflection portion 22 Reflective layer SF Surface HF Rear surface

Claims (4)

A backlight device using a light guide plate that is a transparent or translucent optical medium and has a diffusely reflected portion formed on the surface thereof,
A plurality of the light guide plates are arranged to overlap,
Each light guide plate emits illumination light from the surface by a light source disposed on an end surface of the plurality of light guide plates, and illumination light emitted from the surface of each light guide plate is added,
A backlight device characterized by that. Each of the plurality of light guide plates has the irregular reflection portion formed on the back surface.
A white reflective layer that covers the irregularly reflected portion is formed on the back surface of the lowermost light guide plate of the plurality of light guide plates stacked,
The backlight device according to claim 1. The light source is arranged so that light is incident on each end face of the plurality of the light guide plates stacked,
The backlight device according to claim 2. The irregular reflection portion is formed at a position shifted from each other in the plurality of the light guide plates stacked,
The backlight device according to claim 2 or 3.

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