JPH0530803U - Light guide plate device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a light guide plate device capable of eliminating unevenness in brightness of a light emitting surface due to abnormal light emission and maintaining high brightness and uniformity. [Structure] The light source 2 is arranged outside the end surface of the light guide plate 1, and the light of the light source 2 is provided on both front and back ends of the light guide plate 1 on the side where the light source 2 is arranged via adhesive layers 13 and 13 '. Is a light guide plate device in which a diffusing plate 4 is attached to the front surface and a diffusing plate 4 is attached to the back surface so that there is no gap with the reflecting film 8 Among the adhesive layers 13 and 13 ', at least the adhesive layer 13 on the diffusion plate 4 side is the diffusion plate
It is provided at a position separated from the joint portion 9 between the reflection film 4 and the reflection film 8.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a backlight used for a display of a liquid crystal television, a personal computer or the like, and more particularly to a light guide plate device used as a liquid crystal display plate.

[0002]

[Prior Art]

 As shown in FIG. 5, a conventional light guide plate device includes a light guide plate 21 having both front and back surfaces and an outer peripheral end face, a light source 22 arranged outside the end face of the light guide plate 21, and the light source 22. On both sides of the light guide plate 21 on the side where the reflection film 28 is provided, the reflection film 28 attached through the adhesive layers 33 and 33 ', and the guide film 28 so that there is no gap between the reflection film 28 and the reflection film 28. It has a diffusion plate 24 attached to the front surface of the optical plate 21 and a reflection plate 27 attached to the back surface thereof.

The adhesive layers 33, 33 ′ are ones in which an adhesive such as a double-sided tape is attached to the entire surfaces of the end portions 23, 26 of the light guide plate 21, and the adhesive layers 33, 33 ′ are The reflection film 28, which covers the light source 22 and is provided for shading, is fixed to the end portions 23 and 26 of the light guide plate 21.

[0004]

[Problems to be solved by the device]

 In the above light guide plate device, the light from the light source 22 entering the adhesive layers 33, 33 'is diffusely reflected by the adhesive material, and when the light is guided to the diffuser plate 24, especially at the end of the diffuser plate 24. The light emission in part 35 becomes abnormal light emission A (see FIG. 5).

Therefore, as shown in FIG. 6, the reflection film 28 is separated from the edge portions 29, 30 of the diffuser plate 24 and the reflector plate 27 by a predetermined distance, that is, the ends of the front and back both end portions 23, 26 of the light guide plate 21. Considering a light guide plate device in which an adhesive is attached only to the parts 31 and 32 and the reflection film 28 is fixed to the end parts 31 and 32 thereof.

However, in the light guide plate device, although the abnormal light emission rate at the end portion 35 of the diffusion plate 24 is reduced, the diffuse reflection light generated by the adhesive material of the adhesive layers 33 and 33 ′ is diffused. The light is emitted from the exposed portion of the light guide plate 21 between the edge portion 29 of the plate 24 and the reflective film 28, which causes unnecessary light emission B (see FIG. 6) and causes a decrease in brightness. I ended up.

Therefore, the light guide plate device of the present invention has been improved so as not to cause the above-mentioned abnormal light emission, and it is possible to eliminate the unevenness of the brightness of the light emitting surface due to the abnormal light emission and to maintain high brightness and uniformity. It is an object of the present invention to provide a light guide plate device having the above structure.

[0008]

[Means for Solving the Problems]

 The present invention takes the following technical means in order to achieve the above object.

That is, a light guide plate having both front and back surfaces and an outer peripheral end surface, a light source arranged outside the end surface of the light guide plate, and a front and back surface of the light guide plate on the side where the light source is disposed A reflection film is attached to the end portion via an adhesive layer, a diffusion plate is attached to the front surface of the light guide plate so as not to have a gap with the reflection film, and is attached to the back surface thereof. In the light guide plate device having a reflection plate, the adhesive layer at least on the diffusion plate side is provided at a position separated from the joint between the diffusion plate and the reflection film.

[0010]

[Action]

 In the light guide plate device of the present invention, the reflective film that shields the light from the light source is bonded to the diffuser plate and the reflective plate so that there is no gap between them, and at least the diffuser plate is an adhesive layer that fixes the reflective film. The adhesive layer on the side is provided at a position separated from the joint between the diffusion plate and the reflection film, and is not provided on the entire surface end portion where the light guide plate is exposed, so as shown in FIG. Even if diffuse reflection occurs in the adhesive material of the adhesive layer 13, this diffuse reflection is extinguished in the reflection film attachment portion C where the adhesive layer 13 is not provided, and abnormal light emission occurs on the light emitting surface of the diffusion plate 4. There is nothing to do.

[0011]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the light guide plate device according to the present invention is made of a transparent resin plate having a high light transmittance such as acrylic resin, polycarbonate, AS, and PET, or a front and back surface made of a transparent glass plate. The light guide plate 1 has a rectangular parallelepiped shape having both surfaces and an outer peripheral end surface, and a light source 2 arranged on both sides of the light guide plate 1 or outside one end surface of the light source plate 2.

Except for the end 3 on the side where the light source 2 is arranged, the surface of the light guide plate 1 is a single or a plurality of superposed diffuser plates 4 made of translucent polycarbonate or the like with high transmittance. Is provided as a light emitting surface.

Further, the back surface of the light guide plate 1 is subjected to a dot-like processing 5 such as scratches and screen printing for diffusely reflecting and uniformly diffusing light.

On the back surface side of the light guide plate 1, except for the end portion 6 on the side where the light source 2 is arranged, for example, white polyester for preventing light leakage, or silver on the inner surface of the polyester film is used. A reflector 7 is provided which is formed by attaching a vapor deposition film.

On the other hand, as the light source 2, a high-luminance one such as a hot cathode discharge lamp is used, but the light source 2 is also a small cold cathode discharge lamp in response to the recent thin and light guide body. Are often used, for example, those with a diameter of about 3 mm to 6 mm may be used.

The light sources 2 and the light guide plate 1 are covered at their ends 3 and 6 on both the front and back sides with their outer peripheries, for example, silver or gold colored foil, aluminum foil, aluminum coated silver paper, aluminum coated film A light-shielding reflection film 8 made of a sheet is provided, and the reflection film 8 is joined to the diffusion plate 4 and the reflection plate 7 so as not to have a gap so that the light of the light source 2 does not leak.

A position at a certain distance from the joints 9 and 10 of the diffusion plate 5 and the reflection plate 7 and the reflection film 8, for example, the end portions 11 and 12 of the front and back end portions 3 and 6 of the light guide plate 1 (light source). Adhesive layers 13 and 13 'are provided only on the side closer to 2 (about 3/5 to 5/8), and the adhesive is applied here, and the reflection film 8 is attached to the light guide plate at its end portions 11 and 12. It is stuck to 1. It is preferable that the adhesive layers 13 and 13 'are non-transparent (for example, painted black) because they can also serve as a light shield. Also, an adhesive such as a double-sided tape may be attached to the adhesive layers 13 and 13 '.

Further, in order to further strengthen the light guide plate device, as shown in FIG. 2, a cover which covers the reflection film 8 and is made of an aluminum plate, a polyester film, a vinyl chloride film or the like, which also serves as a light shield and a reflection. It is also possible that 14 is provided.

When the light guide plate device configured as described above is used, diffuse reflection occurs at the end portions 11 and 12 of the light guide plate 1 where the adhesive layers 13 and 13 ′ are provided, as shown by the arrows in FIG. However, the light does not directly enter the diffuser plate 4, and is blocked by the reflection film attachment part C where the adhesive layers 13 and 13 'are not provided, and the diffuse reflection is extinguished. , No abnormal light emission occurs.

In a light guide plate device or the like provided with a cover 14 as shown in FIG. 2, especially only the adhesive layer 13 on the diffusion plate 4 side is removed from the joint 9 between the diffusion plate 4 and the reflection film 8. The adhesive layer 13 ′ on the side of the reflection plate 7 may be provided at positions separated from each other, and may be provided on the entire surface edge of the surface where the light guide plate 1 is exposed. The point is that diffuse reflection caused by the adhesive in the adhesive layer need not be directly guided into the diffusion plate 4.

Next, the results of measuring the luminance of the embodiment of the present invention shown in FIG. 1 and the conventional example shown in FIG. 5 will be described.

The light guide device according to the embodiment of the present invention and the light guide device according to the conventional example are provided by comparing the materials of the light guide plate 1 and the type, number, strength, etc. of the light sources 2 with each other. The light guide plate device used is as described below.

<Conditions Common to Examples and Conventional Examples> Thickness of light guide plate: 5.0 mm Overall size: 280 mm × 210 mm Type / number / strength of light source: Both short-side incident light Cold cathode discharge lamp ( φ4.8 mm) Adhesive used: Double-sided tape (non-transparent) The adhesive layer in the example is the end of the front and back surfaces where the light guide plate is exposed, which is closer to the light source, about 3/5. Use the one provided in the section.

Using the light guide plate devices of the example and the conventional example as described above, the brightness comparison measurement was performed for each distance from the light source 2, and the brightness was graphed. The result is shown in FIG.

From the above comparative measurement results, in the light guide plate device of the embodiment, it is found that abnormal light emission that is likely to occur at the joint 9 between the diffuser plate 5 and the reflective film 8 hardly occurs, and there is no uneven brightness and high uniformity. It can be said that it is now possible to have.

[0027]

[Effect of the device]

 In the light guide plate device of the present invention, the reflection film that shields the light from the light source is bonded to the diffusion plate and the reflection plate so that there is no space between them, and the light is completely shielded. Of the layers, at least the adhesive layer on the diffuser plate side is provided at a position apart from the joint between the diffuser plate and the reflective film, so that even if diffused reflection occurs in the adhesive layer, the diffused reflected light It is extinguished by the reflection film and is not directly guided into the diffuser plate, so there is no abnormal light emission on the light emitting surface.

Therefore, in the light guide plate device of the present invention, there is almost no unevenness in the brightness of the light emitting surface due to abnormal light emission, and there is almost no wasteful light emission, so that it is possible to maintain high brightness and uniformity.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing another embodiment of the present invention.

FIG. 3 is a cross-sectional explanatory view showing how to guide the same light.

FIG. 4 is a graph showing a comparison between an example of the present invention and a conventional example.

FIG. 5 is a cross-sectional view of a main part showing a conventional example.

FIG. 6 is a sectional view of an essential part showing another conventional example.

[Explanation of symbols]

 1 Light guide plate 2 Light source 3 Front end 4 of light guide plate 4 Diffusion plate 6 Back end of light guide plate 7 Reflector 8 Reflective film 9 Bonding part 10 Bonding part 13 Adhesive layer 13 'Adhesive layer 13 A Abnormal light emission

Claims (1)

[Scope of utility model registration request] 1. A light guide plate having both front and back surfaces and an outer peripheral end surface.
(1) and a light source arranged outside the end face of the light guide plate (1)
(2) and the light guide plate on the side where the light source (2) is disposed
Adhesive layers (13), (13 ') on both sides (3), (6) of (1)
And a diffuser plate (4) attached to the surface of the light guide plate (1) so as not to have a gap with the reflective film (8), and a reflective film (8) attached to Attached reflector
In the light guide plate device having (7), at least the adhesive layer (13) on the diffusion plate (4) side is separated from the joint portion (9) between the diffusion plate (4) and the reflection film (8). A light guide plate device, which is provided at a position.