JP2000206526A - Light transmission plate and surface light source device and display device using the light transmission plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light transmission plate in which abnormal diffusion of light in a part where a reflection sheet is fixed can be suppressed and uniform luminance can be obtd. without requiring a special double face adhesive tape, and to provide a surface light source device and a display device without irregular luminance by using this light transmission plate. SOLUTION: Plural recesses 14 are formed in a fixing region S where a reflection sheet 3 is to be fixed, and a reflection sheet 3 is fixed in this fixing region S by using a double face tape 4. Thereby, unnecessary diffusion in the surface part of the light transmission plate in contact with the double tape 4 is suppressed, such irregular luminance that a part of the light emitting face 12 is excessively bright can be prevented, and uniform luminance can be obtd. By using this light transmission plate, a surface light source device having good illumination performance or a display device having excellent display performance can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate, a surface light source device and a display device using the light guide plate, and more particularly, to a reflection sheet for reflecting light from a light source and introducing the light into the light guide plate by a double-sided tape. The present invention relates to a device fixed to a light guide plate.

[0002]

2. Description of the Related Art In a non-light-emitting display device represented by a liquid crystal display device, for example, when it is incorporated into a product such as a digital still camera, a video camera, or a liquid crystal television, a surface is provided on the rear surface of the device for illumination. A backlight unit as a light source device is provided. As one structure of the backlight unit, a light source, a light guide plate that receives light from the light source from the side and emits light from the entire surface, and condenses light emitted from the light guide plate surface (emitted light) within a viewing angle. There is known a lens sheet for improving brightness. Then, in order to introduce light from the light source into the light guide plate, a reflection sheet (light source light reflection sheet) is provided around the light source except for an end surface facing the light guide plate. This reflection sheet is usually fixed around the light introduction end face of the light guide plate with a double-sided tape.

When the reflection sheet is fixed with a double-sided tape, it is non-transparent because the double-sided tape is based on a non-woven fabric. Therefore, unnecessary diffusion occurs in a light guide plate portion to which the double-sided tape is adhered. Luminance non-uniformity occurred in which a part of the emission surface glowed abnormally brightly. Therefore, for example, in Japanese Patent Application Laid-Open No. Hei 8-54624, the unevenness in brightness is reduced by using a double-sided tape for fixing the reflection sheet, which is colored so as to absorb light or to which graphite is added.

[0004]

However, if light is absorbed by the double-sided tape in order to suppress luminance unevenness, light from the light source may not be used efficiently. Since such a double-sided tape is required, there is a possibility that the cost of the surface light source device and the display device may be increased. In the market for such an apparatus, demands for cost reduction are severe, and even a small increase in cost may significantly reduce competitiveness.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to suppress abnormal light diffusion at a fixing portion of a reflection sheet and provide uniform luminance without requiring a special double-sided tape. It is an object of the present invention to provide a light guide plate capable of performing the method, and further to provide a surface light source device and a display device using the light guide plate and having no uneven brightness.

[0006]

According to a first aspect of the present invention, there is provided a light guide plate having a side end face on which light from a light source is incident, an exit surface on which the incident light is emitted, and a facing surface facing the exit surface. Wherein a plurality of recesses are formed in a fixing region for fixing a reflecting member for causing light from a light source disposed opposite to the side end face to be incident on the side end face.

According to a second aspect of the present invention, there is provided the light guide plate according to the first aspect, wherein the fixed region is formed near a side end surface side of the light emitting surface and the facing surface.

According to a third aspect of the present invention, in the light guide plate according to the first or second aspect, the plurality of recesses have a bottom surface wider than the opening.

According to a fourth aspect of the present invention, in the light guide plate according to the first to third aspects, the plurality of recesses are a plurality of grooves in a direction perpendicular to the side end surface.

According to a fifth aspect of the present invention, in the light guide plate according to the first to third aspects, the plurality of recesses are arranged and formed in a lattice.

According to a sixth aspect of the present invention, there is provided a surface light source device according to any one of the first to fifth aspects, a light source disposed opposite to a side end face of the light guide plate, and a light source for receiving light from the light source. A reflecting member for making the light incident on the end face, wherein the reflecting member is fixed to the fixing region with a double-sided tape.

According to a seventh aspect of the present invention, there is provided a display device comprising the surface light source device according to the sixth aspect and non-light emitting display means provided on an emission surface side of the light guide plate.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a light guide plate, a surface light source device,
FIG. 1 is a schematic configuration diagram of an embodiment of a display device.

Reference numeral 1 denotes a light guide plate made of a light-transmitting material, which is an incident surface 11 which is a side end surface on which light is incident, an output surface 12 for emitting light incident from the incident surface 11 to the outside of the light guide plate, and an output surface 1.
2 is provided with a back surface 13 which is a facing surface opposed to the second surface 2. The other three surfaces are reflection surfaces so that light incident in a mirror state does not leak, and a reflection material is provided as necessary.

The back surface 13 is provided with a diffusion layer 13a for diffusing the incident light in the direction of the light exit surface 12. The diffusion layer 13a is formed, for example, by an appropriate diffusion pattern made of irregularities on the light guide plate 1. Some of them are integrally formed, and others have a diffusion pattern printed on the back surface 13 with ink to which a light diffusing agent is added.

Reference numeral 2 denotes a linear light source such as a cold-cathode fluorescent lamp which is disposed on the side of the incident surface 11, and 3 denotes a reflecting sheet as a reflecting member provided in a region other than a region facing the incident surface 11 of the light source 2. Reference numeral 4 denotes a double-sided tape for fixing the reflection sheet 3 to the fixing area S of the light guide plate 1.

Reference numeral 5 denotes a diffusion plate provided to face the emission surface 12 for uniformly distributing the emitted light, and 6 denotes a non-light emitting display means provided on the emission surface 12 side with the diffusion plate 5 interposed therebetween. It is a panel. Reference numeral 7 denotes a reflector for returning light leaked from the back surface 13 into the light guide plate 1 again.

FIG. 2 is an explanatory perspective view of the light guide plate 1.

On the exit surface 12 and the back surface 13, there is a fixing area S for fixing the reflection sheet 3 by adhering the double-sided tape 4 near the edge of the incident surface 11, and the fixing area S has a plurality of concave portions. 14 are formed. The concave portion 14 is a groove extending in a direction orthogonal to the incident surface 11 in FIG.
For example, the grooves (recesses 14) are formed at a pitch of 0.5 to 1 / mm and at a depth (for example, 0.1 mm) at which the adhesive surface of the double-sided tape does not contact the bottom surface. In addition, the groove (recess 1)
4) The occupation area ratio in the fixed region S is 1/2.
The above is desirable. For example, if the grooves are provided at a pitch of 1 / mm, the width of the groove (recess 14) is preferably 0.5 mm or more and the distance between the grooves is preferably 0.5 mm or less. The larger the proportion of the occupied area, the better. However, in order to secure the adhesive force between the double-sided tape 4 and the light guide plate 1 (fixed area S), about 9/10 (for example, at a pitch of 1 groove / mm). If provided, the width of the groove (recess 14) is 0.9 mm and the distance between the grooves is 0.1 m.
m, but the depth need not be limited to 0.1 mm).

Incidentally, such a light guide plate is usually formed by injection molding using a thermoplastic resin. The light guide plate provided with the fixing region having the concave portion can be integrally and simply formed by a simple molding process.

As described above, the fixing of the reflection sheet 3 to the light guide plate 1 is performed by adhering the double-sided tape 4 to the fixing area S, and further adhering the end of the reflection sheet 3 to the double-sided tape 4. You. At this time, the light guide plate 1 and the double-sided tape 4 are fixed to the surface (the emission surface 1) other than the groove (recess 14) in the fixed region S.
2 or the surface at the same height as the back surface 13).

When used as a surface light source device or a display device, the light from the light source 2 is directly or reflected by the reflection sheet 3 and enters the light guide plate 1 from the entrance surface 11. The incident light propagates through the light guide plate, some are reflected directly or on another surface, some are diffused by the diffusion layer 13a on the back surface, and some are reflected from the back surface 13 once. The light is reflected by the plate 7 and enters the light guide plate 1 again.
After passing through 3a, the light is emitted from the emission surface 12. At this time, a part of the light propagates to the vicinity of the fixing region S, and some light is diffused at the surface of the light guide plate in contact with the double-sided tape 4, but most of the light is reflected at the bottom surface of the concave portion 14 without being diffused. Then, the light is advanced into the light guide plate 1. As a result, unnecessary diffusion by the double-sided tape 4 is minimized, and uniform luminance can be exhibited without causing luminance unevenness such that a part of the emission surface becomes abnormally bright. That is, a surface light source device having good illumination performance can be provided, and further, a display device having excellent display performance can be provided.

Further, the reflection sheet 3 can be fixed by using an ordinary double-sided tape, and the light guide plate can be formed by a usual method, so that there is no possibility that the cost is increased, and therefore, a product having high market competitiveness is provided. Can be.

FIG. 3 shows another embodiment according to the present invention, and explains another pattern shape of the concave portion formed in the fixed region S. In FIGS. 1 and 2, the plurality of recesses 14 are grooves. However, each of the plurality of recesses 15 has a circular opening in FIGS. 3A and a square in FIGS. 3B and C. 3B is obliquely arranged. Although not limited to these,
In any case, the adhesive surface of the double-sided tape (fixed area S)
On the other hand, since the surface where the light guide plate and the double-sided tape are bonded is reduced, unnecessary diffusion on the bonded surface can be suppressed.
Further, since the concave portions 15 are arranged in a dispersed manner, the adhesion by the double-sided tape is uniform without unevenness, and the reflection sheet is properly fixed to the light guide plate.

Each of the plurality of recesses may have the same size as the opening and the bottom as shown in FIG. 2, but the bottom 16b is wider than the opening 16a as shown in FIG. The recess 16 may be formed. In this case, for example, if the concave portion is a groove, the width of the bottom portion is configured to be wider than the width of the opening portion, and if the concave portion is circular or square, the area of the bottom portion is configured to be wider than the area of the opening portion. You. This makes it possible to further increase the adhesive strength of the double-sided tape while suppressing unnecessary diffusion on the bonding surface between the double-sided tape and the light guide plate.

[0027]

According to the present invention, as is apparent from the above description, a plurality of recesses arranged in a groove or a lattice are formed in a fixing area for fixing a reflection sheet, and a double-sided tape is used in this fixing area. Since the reflection sheet is fixed in this way, unnecessary diffusion by the double-sided tape can be minimized without using a special double-sided tape. This makes it possible to exhibit uniform luminance without causing luminance unevenness such that a part of the emission surface becomes abnormally bright.

Further, by making the opening of the concave portion wider than the bottom portion, the adhesive strength by the double-sided tape can be sufficiently secured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment according to the present invention.

FIG. 2 is a perspective explanatory view of one embodiment according to the light guide plate of the present invention.

FIG. 3 is an explanatory view of a concave portion of another embodiment according to the light guide plate of the present invention.

FIG. 4 is an explanatory cross-sectional view of a concave portion according to another embodiment of the light guide plate of the present invention.

[Explanation of symbols]

 Reference Signs List 1 light guide plate 11 incident surface (side end surface) 12 emission surface 13 back surface (opposing surface) S fixed region 14, 15, 16 recess 16a opening 16b bottom surface 2 light source 3 reflection sheet (reflection member) 4 double-sided tape 6 liquid crystal display panel (Non-light emitting display means)

Claims (7)

[Claims] 1. A light guide plate having a side end surface on which light from a light source is incident, an exit surface from which the incident light is emitted, and a facing surface facing the emission surface, wherein the light of the light source is disposed opposite to the side end surface. A light guide plate, wherein a plurality of concave portions are formed in a fixing region for fixing a reflecting member for making the light incident on the side end surface. 2. The light guide plate according to claim 1, wherein the fixed region is formed near a side end surface side of the light emitting surface and the facing surface. 3. The light guide plate according to claim 1, wherein a bottom surface of each of the plurality of recesses is wider than an opening. 4. The light guide plate according to claim 1, wherein the plurality of recesses are a plurality of grooves in a direction orthogonal to the side end surface. 5. The light guide plate according to claim 1, wherein the plurality of recesses are arranged and formed in a grid. 6. A light guide plate according to claim 1, further comprising: a light source disposed to face the side end surface of the light guide plate; and a reflecting member for causing light from the light source to enter the side end surface. ,
The surface light source device, wherein the reflection member is fixed to the fixing region with a double-sided tape. 7. A display device comprising: the surface light source device according to claim 6; and a non-light-emitting display unit provided on an emission surface side of the light guide plate.