JP2518851Y2 - Light guide plate device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight used for a display such as a liquid crystal television and a personal computer, and more particularly to a light guide plate device used as a liquid crystal display panel.

[0002]

2. Description of the Related Art A conventional light guide plate device includes a light guide plate 21 having front and back surfaces and an outer peripheral end surface as shown in FIG.
Of the light source 22 disposed outside the end surface of the light guide plate 21, and both ends 23, 26 of the front and back surfaces of the light guide plate 21 on the side where the light source 22 is disposed.
, The reflective film 28 attached via the adhesive layer 33, 33 '.
And a diffusion plate 24 attached to the front surface of the light guide plate 21 so as not to have a gap with the reflection film 28, and a reflection plate 27 attached to the back surface thereof.

The adhesive layers 33, 33 ′ are formed on the end portion 2 of the light guide plate 21.
An adhesive such as a double-sided tape is adhered to the entire surface of 3,26, and the reflective film 28 provided for light shielding by covering the light source 22 with the adhesive layers 33, 33 'is the conductive layer. It was fixed to the end portions 23 and 26 of the light plate 21.

[0004]

In the above light guide plate device,
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 diffusion plate 24, light is emitted particularly at the end portion 35 of the diffusion plate 24. Abnormal light emission A (see Fig. 5).

Therefore, as shown in FIG.
A position apart from the edge portions 29, 30 of the diffuser plate 24 and the reflector plate 27 by a predetermined distance, that is, by attaching an adhesive only to the end portions 31 and 32 of the front and back double-sided end portions 23 and 26 of the light guide plate 21, Its ends 31,32
Then, a light guide plate device having the reflection film 28 fixed thereto was considered.

However, in the light guide plate device, the diffusion plate 24
Although the abnormal light emission rate at the end portion 35 of the is reduced, diffused reflection light generated by the adhesive material of the adhesive layer 33, 33 'is diffused.
Since the light is emitted from the exposed portion of the light guide plate 21 between the edge portion 29 of 24 and the reflection film 28, unnecessary light emission B (see FIG. 6) increases, causing a decrease in brightness. Oops.

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

[0008]

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 both ends of the front and back surfaces of the light guide plate on the side where the light source is disposed. Portion, a reflection film attached via an adhesive layer, a diffusion plate attached to the front surface of the light guide plate so as not to have a gap with the reflection film, and a reflection plate attached to the back surface thereof. In the light guide plate device having, 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]

In the light guide plate device of the present invention, the reflection film for shielding the light from the light source is bonded to the diffusion plate and the reflection plate so that there is no gap between them. Since at least the adhesive layer on the diffuser plate side is provided at a position separated from the joint between the diffuser plate and the reflection film and is not provided on the entire surface end portion where the light guide plate is exposed, it is shown in FIG. Thus, 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 in the portion where the adhesive layer 13 is not provided,
No abnormal light emission occurs on the light emitting surface of the diffusion plate 4.

[0011]

Embodiments of the present invention will be described in detail below 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 acrylic resin, polycarbonate, AS, P.
A rectangular parallelepiped light guide plate 1 having both front and back surfaces and an outer peripheral end face, which are made of a transparent resin plate having a high light transmittance such as ET or a transparent glass plate, and are arranged apart from each other on one side or one side end face. It is equipped with a light source 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 having a 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 irregularly reflecting and uniformly diffusing light.

On the back side of the light guide plate 1, the light source is further provided.
Except for the end portion 6 on the side where 2 is arranged, for example, white light polyester for preventing light leakage, or a reflector 7 constituted by sticking a silver vapor deposition film on the inner surface of a polyester film is provided.

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

Ends on both the front and back sides of the light source 2 and the light guide plate 1.
3 and 6 are light-shielding reflective films that cover the outer periphery and are made of metal vapor deposition sheets such as silver or gold colored foil, aluminum foil, aluminum-coated silver paper, aluminum-coated film, etc.
8 is provided, and this 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.

The diffusion plate 5 and the reflection plate 7 and the reflection film
8 is a position spaced from the joints 9 and 10 at a predetermined distance, for example, the end portions 11 and 12 of the front and back end portions 3 and 6 of the light guide plate 1 (the light source 2
The adhesive layer 13, 13 ′ is provided only on the side closer to (about 3/5 to 5/8), and the adhesive is applied here, and the reflection film 8 is connected to the light guide plate 1 at its end portions 11 and 12. It is fixed. It is preferable that the adhesive layers 13 and 13 'are non-transmissive (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 '.

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

When the light guide plate device constructed as described above is used, as shown by the arrow in FIG. 3, 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. However, the light is not directly guided into the diffuser plate 4, and is shielded by the reflection film attachment portion C where the adhesive layers 13 and 13 'are not provided, so that the diffuse reflection is extinguished. , No abnormal light emission occurs.

In the light guide plate device and the like provided with the cover 14 as shown in FIG. 2, especially only the adhesive layer 13 on the diffusion plate 4 side is provided 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 a separated position.
May be provided on the entire surface of the exposed end portion of the light guide plate 1.
In short, the diffuse reflection caused by the adhesive in the adhesive layer
It does not have to be directly guided inside.

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 of the embodiment of the present invention and the light guide device of the conventional example are made by comparing the materials of the light guide plate 1 and the type, number, strength and the like 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 x 210 mm Type / number / strength of light source: Both short-side incident 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 above-described light guide plate apparatus of the embodiment and the conventional example, the brightness comparison measurement was performed for each distance from the light source 2, and the brightness was plotted in a graph. FIG. 4 shows the results.

From the above comparative measurement results, it is understood that in the light guide plate device of the embodiment, abnormal light emission which is likely to occur at the joint portion 9 between the diffuser plate 5 and the reflection film 8 hardly occurs.
It can be said that a high degree of uniformity can be achieved without uneven brightness.

[0027]

In the light guide plate device of the present invention, the reflection film for shielding the light from the light source is joined to the diffusion plate and the reflection plate so as not to have a gap and is completely shielded. Of the adhesive layers to be fixed, 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 reflection film, so that even if diffuse reflection occurs in the adhesive layer, The diffusely reflected light is extinguished by the reflection film and is not directly guided into the diffuser plate, so that no abnormal light emission occurs on the light emitting surface.

Therefore, in the light guide plate device of the present invention, the unevenness of the brightness of the light emitting surface due to the abnormal light emission is almost eliminated, and the useless light emission is hardly generated, so that the high brightness and the uniformity can be maintained.

[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 sectional view of a main part showing another embodiment of the present invention.

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

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)

(57) [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)
A reflection film (8) attached via the light guide plate (1) and a diffusion plate (4) attached to the surface of the light guide plate (1) so that there is no gap between the reflection film (8) and the reflection film (8). 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.