JPH08146226A - Surface light source device - Google Patents

Abstract

PURPOSE: To provide a surface light source device in which a reflection sheet is appropriately ranged on the back of the reflection surface of a light transmission plate even when the shape of the reflection surface of the light transmission plate is complicated. CONSTITUTION: A diffusion sheet 5, the light transmission plate 3, the reflection sheet 4, and a compression member 8 are successively superposed and arranged on the main body 1A of a case 1 incorporating a fluorescent tube 2, and finally a base plate 1B is attached to the main body 1A by a screw 9. The reflection surface 3b of the light transmission plate 3 is a curved surface and the compression member 8 is pressed by the base plate 1B and compressed and deformed, so that the reflection sheet 4 is pressed to the reflection surface 3b along the curved surface of the reflection surface 3b by the elastic force of the member 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device suitable for use as a backlight mainly in liquid crystal displays such as office automation equipment, televisions, measuring instruments and watches.

[0002]

2. Description of the Related Art A surface light source device has been known for a long time, and a small one is used as a backlight of a wrist watch for liquid crystal display.
Large ones have been used as backlights for advertisement display boards and lighting devices for product display. As the light sources, LEDs are used for small ones and fluorescent tubes are used for large ones. As the light guide plate, an acrylic plate material is cut into an appropriate size to have a predetermined shape. It was used after being processed.

On the other hand, since the surface light source device has a merit that it can be made thin, it has become common in recent years to arrange the light source at a lateral position of the light guide plate, and the light guide plate has stable quality and can be mass-produced. It has come to be manufactured by molding. In such a surface light source device, the light source light incident from the lateral position is bent in a substantially orthogonal direction, and from the exit surface of a predetermined area, as uniform plane light or with a desired luminance distribution,
Moreover, it is necessary to efficiently emit light, and various measures have been made so far.

In order to make the light emitted from the emission surface uniform and to obtain a desired distribution, the opposite surface of the light guide plate, that is, the reflection surface, is parallel to the emission surface. Instead of forming it on a flat surface, it is formed on a plane or a curved surface that is not parallel, and further, fine irregularities are formed on the reflection surface, or painting or printing is partially applied.

In particular, in the case of a scattering type light guide plate (silicon fine particles mixed in acrylic resin) which has recently been adopted, the reflection surface is often formed as a free curved surface instead of a straight surface or an arc surface. Further, in order to improve the overall reflection efficiency, a reflection sheet is arranged on the back of the reflection surface, and as the reflection sheet, a P of about 0.12 mm is usually used.
A white sheet of ET (polyethylene terephthalate) is often used, but recently, a PET sheet on which silver is vapor-deposited is used.
What is called a silver sheet of 08 to 0.16 mm has come to be used.

An example of a conventional surface light source device is shown in FIG.
Since the above is shown as a cross-sectional view, a conventional method of arranging the reflection sheet will be described with reference to this drawing. First, the structure of this surface light source device will be described. The main body 1A of the case 1 accommodates a fluorescent tube 2 as a light source, and the light guide plate 3 has an incident surface 3a on the fluorescent tube 2. Facing each other,
The reflective surface 3b and the front end surface 3c are mounted in the case 1 so as to be covered by the bottom plate 1B of the case 1 and the side wall 1a of the main body 1A, respectively. Further, the reflection sheet 4 is arranged between the reflection surface 3b and the bottom plate 1B. Therefore, the light source light from the fluorescent tube 2 incident from the incident surface 3a of the light guide plate 3 is reflected generally upward by the reflection sheet 4 as a whole, and is emitted from the emission surface 3d through the diffusion sheet 5 with a predetermined luminance distribution. Is emitted.

In such a structure, as a matter of course, it is preferable that the reflection sheet 4 is arranged so as not to have wrinkles and ideally in contact with the reflection surface 3b. Therefore, conventionally, the reflection sheet 4 is attached to the periphery of the reflection surface 3b with a double-sided tape or the like, or after the reflection sheet 4 is attached to the bottom plate 1b, the reflection sheet 4 is pressed against the reflection surface 3b by the bottom plate 1b. I was like.

[0008]

However, when a reflection sheet is attached to the peripheral portion of the reflection surface of the light guide plate with a double-sided tape as described above, abnormal light emission or light loss occurs at the place where the tape is attached. However, there is a problem in that it is difficult to obtain a highly accurate surface light source device, and in the case of a thin silver sheet, wrinkles easily occur in a region where the tape does not exist.
Furthermore, when the shape of the reflecting surface of the light guide plate is a free-form surface, the reflecting sheet cannot be brought into uniform contact with the reflecting surface, and a gap is partially formed to obtain a predetermined reflecting effect. There was a problem that it did not exist.

After attaching the reflection sheet to the bottom plate,
When the reflection sheet is pressed against the reflection surface by the bottom plate, it is difficult to fabricate the shape of the bottom plate according to the shape of the reflection surface unless the reflection surface is a straight surface. If the shape is a free-form surface, it is extremely difficult to manufacture the bottom plate.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a light guide plate having a reflection surface of any complicated shape. An object of the present invention is to provide a surface light source device capable of appropriately disposing a reflection sheet on the back part of the reflection surface.

[0011]

In order to achieve the above object, the surface light source device of the present invention has a light source light incident surface on the side, an emission surface on the front side, and a reflection surface on the rear side. A light guide plate, a reflection sheet arranged on the back of the reflection surface, a pressing member provided on the back of the reflection sheet, the light guide plate provided between the reflection sheet and the pressing member, and And a compression member that can be compressed and deformed by the pressing member. Further, preferably, in the surface light source device of the present invention, the compression member is provided over substantially the entire area of the reflection surface, and the pressing member is disposed between the compression member and the case.

[0012]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of an embodiment of the present invention, and FIG. 2 is a sectional view of the embodiment of the present invention in an assembled state.
FIG. 3 is a perspective view showing a modified example of the compression member applied to the embodiment of the present invention. It should be noted that, of the reference numerals shown in FIGS. 1 to 3, the same reference numerals as those of the prior art parts and portions shown in FIG. 4 are used even if the shapes are changed. .

1 and 2, the body 1 of the case 1
In A, side walls 1b and 1c are formed in addition to the side wall 1a, and holes 1d and 1e are provided. Sockets 6 and 7 for connecting the fluorescent tube 2 are attached to the holes 1d and 1e.
The bottom plate 1B of the case 1 has six holes 1f (only five are shown in FIG. 1), and the diffusion sheet 5, the light guide plate 3, the reflection sheet 4, and the compression member 8 are arranged in this order in the main body 1A. After being housed, it is attached to the body 1A as shown in FIG. 2 with six (only two shown in FIG. 2) screws 9.

In the above structure, the reflecting surface 3 of the light guide plate 3
Unlike the conventional example shown in FIG. 4, b has a curved surface instead of a straight surface. Further, the compression member 8 is normally shown in FIG.
Although it has a predetermined uniform thickness as shown in FIG. 3, it is made to be compressed and deformed when pressed by a member that is stiffer than itself. Therefore, as shown in FIG. 2, when the bottom plate 1B is attached to the main body 1A by the screws 9, the compression member 8 is pushed by the bottom plate 1B and compressed, and the elastic force generated thereby causes the extremely thin flexible member as described above. The reflective sheet 3 having the property of reflecting the reflective surface 3b of the light guide plate 3
Press it so that it fits into the curved surface of.

A thermoplastic elastomer such as styrene / butadiene type, polyolefin type or polyester type is suitable as a material for imparting such characteristics to the compression member 8. In addition to this, a porous material having compressive elasticity, such as chlorinated polyethylene, ethylene vinyl acetate, polybutadiene, or polyurethane, can be applied, and silicone rubber can also be used.

The normal shape of the compression member 8 need not be limited to the rectangular parallelepiped as shown in FIG. For example, in FIG. 2, the portion closer to the fluorescent tube 2 may be thicker and the closer it is to the side wall 1a, the thinner it may be, or vice versa. Also, the surface does not have to be flat,
It may be an arc surface or an uneven surface. The point is that, as shown in FIG. 2, a shape that allows the reflection sheet 4 to be evenly pressed against the reflection surface 3b of the light guide plate 3 is sufficient.

Although the compression member 8 is in contact with the entire surface of the reflection sheet 4 in FIG. 2, it is not always necessary to do so. A modification of the compression member 8 is shown in FIG. The compression member 8 has a plurality of ribs 8b in the longitudinal direction on the base 8a and a plurality of ribs 8c in the lateral direction. The height of the rib 8b in the longitudinal direction increases from the base portion 8a in the upper right direction. Of course, the material is the same as the above case. The number of ribs 8b and 8c may be increased or decreased depending on the material and thickness of the reflection sheet 4, or depending on the case, only one of the ribs 8b and 8c may be used. Further, in FIG. 3, although the shape is such that it is surrounded by the ribs 8b and 8c to form a square hole, the hole may be a circular hole.
The base portion 8a may be omitted.

In the embodiment shown in FIGS. 1 and 2, the pressing member for pressing the compression member 8 toward the light guide plate 3 is the bottom plate 1.
Although it is B, a separate pressing member having an appropriate shape may be arranged between the compression member 8 and the bottom plate 1B. In some cases, the compression member 8 and the bottom plate 1B may be integrally formed, or the compression member 8 and the separate pressing member may be integrally formed. When they are integrally formed, they may be produced separately, and may be integrated by adhesion, welding or the like, or they may be produced at once by a molding technique.

Although the diffusion sheet 5 is arranged in the embodiment shown in FIGS. 1 and 2, a prism sheet or the like may be arranged instead of the diffusion sheet 5 in the present invention. Good, or it is not necessary to arrange sheets such as those. Furthermore, as a surface light source device,
The surface light source device according to the present invention includes a light source unit separately, although the light source unit may be separately traded.

[0020]

As described above, the surface light source device of the present invention is
Since a compression member is interposed at the back of the reflection sheet and the compression sheet is pressed against the reflection surface of the light guide plate by the compression member, whether the reflection surface is a straight plane surface or a free-form surface, and the reflection sheet is extremely Even with a thin sheet, the reflection sheet can be appropriately arranged on the reflection surface of the light guide plate.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an assembled state of the embodiment of the present invention.

FIG. 3 is a perspective view showing a modified example of the compression member applied to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Case 1A Main Body 1B Bottom Plate 1a, 1b, 1c Side Wall 1d, 1e, 1f Hole 2 Fluorescent Tube 3 Light Guide Plate 3a Incident Surface 3b Reflection Surface 3c Tip Surface 3d Emission Surface 4 Reflection Sheet 5 Diffusion Sheet 6,7 Socket 8 Compression Member 8a Base 8b, 8c Rib 9 Screw

Claims (5)

[Claims] 1. A light guide plate having a light source light incident surface on its side, a light emitting surface on the front, and a reflective surface on the rear, a reflective sheet disposed on the back of the reflective surface, and a reflective sheet of the reflective sheet. A surface light source, comprising: a pressing member provided on a back portion; and a compression member provided between the reflection sheet and the pressing member and compressible and deformable by the light guide plate and the pressing member. apparatus. 2. The surface light source device, wherein the compression member is provided over substantially the entire area of the reflection surface. 3. The pressing member is arranged between the compression member and the case.
The surface light source device according to. 4. The surface light source device according to claim 1, wherein the pressing member is a part of a case. 5. The surface light source device according to claim 1, wherein the pressing member and the compression member are integrally formed.