JPH08110413A - Surface light emitting device - Google Patents

Abstract

PURPOSE: To provide a surface light emitting device having high uniformity and high luminance by approximating the outside dimensions of a light transmission plate to the sizes of an effective display region as far as possible. CONSTITUTION: A linear light source 2 is arranged on the side face of the transparent light transmission plate 1 having the outside dimensions larger than the outside dimensions of the effective display region and the rear surface of the light transmission plate is provided with a light scattering reflection part 3. A rear surface reflection plate 7 is arranged on the surface provided with the light scattering reflection part 3 of the light transmission plat 1. The light transmission plate 1 and the rear surface reflection plate 7 are directly adhered by a transparent adhesive layer 8 nearer the linear light source 2 side than the effective display region 9. Moreover, the linear light source 2 side boundary of the light scattering reflection part forming region 4 of the surface light emitting source in which the linear light source 2 side bound of the effective display region 9 is near the side face arranged with the linear light source 2 of the light transmission plate 1 exists nearer the central side of the light transmission plate 1 than the linear light source 2 side boundary of the effective display region 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge-light type surface emitting device used for thin and lightweight laptop personal computers, word processors, liquid crystal TV backlights and the like.

[0002]

2. Description of the Related Art Conventionally, a line light source is arranged on a side surface of a transparent light guide plate, and a light scattering reflection portion for evenly distributing light from the line light source is provided on a back surface of the light guide plate in a gradation pattern. A light type surface emitting device is used as a backlight of a liquid crystal display device. In the edge-light type surface emitting device, in order to use the light more efficiently, a back reflector is arranged on the surface of the light guide plate on which the light scattering reflection part is provided, or a surface opposite to the light guide plate of the linear light source. A light source reflector is arranged so as to cover the. Further, in order to make the brightness distribution on the surface of the light guide plate more uniform, a light diffusion plate is also arranged on the surface of the light guide plate.

By the way, since the surface emitting device is used for surely illuminating the effective display area 9 of the liquid crystal display module arranged on the front surface from the back, the light scattering reflection portion forming area 4 is equivalent to the effective display area 9. It is considered that the light-scattering is required to be formed in the above size, and usually, the light scattering is performed so that sufficient brightness can be obtained even when the display screen is viewed obliquely or the misregistration with the effective display area 9 is taken into consideration. The reflection portion forming area 4 is larger than the effective display area 9 by about several mm.
That is, first, the minimum range of the light-scattering / reflecting portion forming region 4 is determined, and the gradation pattern of the light-scattering / reflecting portion 3 is determined so that light emission is as uniform as possible on the premise.

However, in the surface emitting device in which the light-scattering / reflecting portion forming region 4 is formed to have a size equal to or larger than the effective display region 9, the light source reflecting plate 5, the back reflecting plate 7, and the light diffusing plate 6 are included in the effective displaying region. 9 has been bonded to the light guide plate 1 by the transparent adhesive layer 8 such as a double-sided tape on the side of the linear light source 2 with respect to 9, and thus has the following problems. That is, when the light emitted from the linear light source 2 strikes the transparent adhesive layer 8 adhered to the light guide plate 1, the light is scattered and reflected, and a part of the light is scattered from the transparent adhesive layer 8 on the surface of the light guide plate 1. The light came out to the center. Moreover, a word processor,
With the miniaturization of personal computers and the like, it has been necessary to satisfy the technical requirement that the outer dimensions of the light guide plate 1 be close to the dimensions of the effective display area 9. As a result, on the side of the linear light source 2 in the effective display area 9 of the surface emitting device, the light-scattering / reflecting portion 3 is provided.
Further, the transparent adhesive layer 8 for the light emitted directly or by
The extraordinarily high brightness was obtained by the addition of the light emitted (see FIG. 5), and linear brightness unevenness 10 was formed along the tube axis direction of the linear light source 2 (see FIG. 6).

Therefore, in order to eliminate the uneven brightness 10, it has been considered to form a black adhesive layer 11 instead of the transparent adhesive layer 8 directly provided on the light guide plate 1. Black adhesive layer 11
Does not scatter and reflect the light emitted from the linear light source 2 and emit the light from the surface of the light guide plate 1. Therefore, even if the outer dimensions of the light guide plate 1 are brought closer to the dimensions of the effective display area 9, only the light emitted by the light scattering reflection part 3 or directly on the side of the linear light source 2 in the effective display area 9 of the surface emitting device. Exists, and the uneven brightness 10 does not occur (see FIG. 7).

[0006]

However, the black adhesive layer 1
In the surface emitting device having the light emitting device 1 formed therein, part of the light emitted from the linear light source 2 to the light transparent adhesive layer 8 is guided to the back of the light guide plate 1, whereas the light emitted to the black adhesive layer 11 is Almost absorbed. Therefore, the surface emitting device using the black adhesive layer 11 has a drawback that the brightness is lowered as a whole.

That is, if the transparent adhesive layer 8 is used to bond the light source reflector 5, the back reflector 7, and the light diffuser 6, the brightness of the entire surface emitting device is sufficient, but uneven brightness occurs, and the black adhesive layer is used. When 11 was used, uniform light emission was obtained, but the brightness of the entire surface emitting device was lowered.

Therefore, an object of the present invention is to make the outer dimensions of the light guide plate 1 as close as possible to the dimensions of the effective display area 9.
Another object of the present invention is to provide a uniform and high-luminance surface emitting device.

[0009]

In order to achieve the above object, in a surface emitting device of the present invention, a line light source is arranged on a side surface of a transparent light guide plate having an outer dimension larger than an effective display area, and a light guide plate of the light guide plate is provided. A light scattering reflector is provided on the back surface, and a back reflector is disposed on the surface of the light guide plate on which the light scattering reflector is provided,
The light guide plate and the back reflector are directly adhered to each other by a transparent adhesive layer on the line light source side of the effective display area, and the line light source side boundary of the effective display area is close to the side surface of the light guide plate on which the line light source is arranged. In the above, the boundary of the light-scattering / reflecting portion forming area on the line light source side is located closer to the center of the light guide plate than the boundary of the effective display area on the linear light source side.

Further, in the surface emitting device of the present invention, the linear light source is disposed on the side surface of the transparent light guide plate having the outer dimensions larger than the effective display area, and the light scattering reflection portion is provided on the back surface of the light guide plate. A light diffusing plate is disposed on the surface of the light guide plate, the light guide plate and the light diffusing plate are directly bonded to each other by a transparent adhesive layer on the line light source side of the effective display area, and the line light source side boundary of the effective display area is the line of the light guide plate. In the surface emitting device near the side surface where the light source is arranged, the boundary of the light-scattering / reflecting portion forming area on the line light source side is located closer to the center of the light guide plate than the boundary of the effective display area on the line light source side.

Further, in the surface emitting device of the present invention, the linear light source is disposed on the side surface of the transparent light guide plate having an outer size larger than the effective display area, and the light scattering reflection portion is provided on the back surface of the light guide plate. The light source reflector is arranged so as to cover the surface on the side opposite to the light guide plate, and the light guide plate and the light source reflector are directly adhered to each other by the transparent adhesive layer on the line light source side from the effective display area,
Further, in the surface emitting device in which the line light source side boundary of the effective display area is closer to the side surface where the line light source of the light guide plate is arranged, the line light source side boundary of the light scattering reflection forming area is closer to the center of the light guide plate than the line light source side boundary of the effective display area. Configured to be on the side.

Further, in the above-mentioned respective structures, in the surface emitting device of the present invention, the distance between the line light source side boundary of the light scattering reflection portion forming region and the line light source side boundary of the effective display region is on the line light source side of the light guide plate. It was configured to be 10 to 100% of the plate thickness.

Embodiments of the surface emitting device of the present invention will be described below in detail with reference to the drawings.

1 to 4 are sectional views showing an embodiment of the surface emitting device according to the present invention. 1 is a light guide plate, 2 is a linear light source,
Reference numeral 3 is a light scattering reflection portion, 4 is a light scattering reflection portion formation region, 5 is a light source reflection plate, 6 is a light diffusion plate, 7 is a back reflection plate, 8 is a transparent adhesive layer, and 9 is an effective display region.

In the surface emitting device shown in FIG. 1, a linear light source 2 is arranged on the side surface of a transparent light guide plate 1 having an outer size larger than the effective display area 9.

The light guide plate 1 is preferably a rectangular plate material having a thickness of about 1.5 to 30 mm. The thickness of the light guide plate 1 is equal to that of the linear light source 2.
You may make it thin as it moves away from it. The material of the light guide plate 1 is not particularly limited as long as it is a substance that allows light to pass efficiently, and for example, a resin such as acrylic, polycarbonate, polystyrene, acrylic styrene, polyvinyl chloride, or glass can be used. . Moreover, it is preferable that all the side surfaces of the light guide plate 1 are finished to be smooth. Further, the boundary of the effective display area 9 on the side of the linear light source 2 exists near the side surface of the light guide plate 1 on which the linear light source 2 is arranged. Specifically, the distance from the side surface is a distance of 1 to 8 mm from the side surface of the light guide plate 1 on which the linear light source 2 is arranged. If this distance exceeds 8 mm, the amount of light emitted from the linear light source 2 will be greatly attenuated and the brightness will decrease, and the size of a word processor, a personal computer, etc. will not be reduced, and if it is less than 1 mm, the light source reflector 5 and the back reflector 7, There is no space for adhering the light diffusion plate 6 to the light guide plate 1.

The linear light source 2 is arranged on at least one side surface of the light guide plate 1. As the line light source 2, a cathode ray tube such as a hot cathode ray tube or a cold cathode ray tube having a diameter of 2 to 3 mm is used. The linear light source 2 may have a straight shape, an L-shape extending over two adjacent side surfaces, or a U-shape extending over three adjacent side surfaces.

A light scattering / reflecting portion 3 is formed on the back surface of the light guide plate 1. The light-scattering / reflecting portion 3 scatters and reflects the light guided from the linear light source 2 into the light guide plate 1 and directs a part of the light toward the front surface side of the light guide plate 1. The light is evenly distributed by enlarging it at a position away from the linear light source 2. In order to change the area ratio of the light-scattering / reflecting portion 3, the light-scattering / reflecting portion 3 is formed of dots having an arbitrary shape,
This is done by changing the dot size or the number of dots depending on the position. The shape of the dot is not particularly limited, and may be any shape such as round dot, square dot, chain dot. Further, instead of dots, it may be formed in a stripe shape. As a method of forming the light scattering / reflecting portion 3, there are a printing method such as screen printing using a matte ink, a transfer method, and a method in which unevenness is provided on the back surface of the light guide plate 1. As the matte ink, if an ink containing a particulate transparent substance such as calcium carbonate or silica having a refractive index substantially equal to or lower than that of the light guide plate 1 is used, the light diffusion property can be further improved.

Further, in the present invention, the light scattering / reflecting portion 3
Is formed so that the boundary of the light-scattering / reflecting portion forming area 4 on the line light source 2 side is closer to the center of the light guide plate 1 than the boundary of the effective display area 9 on the line light source 2 side. That is, the linear light source 2 in the effective display area 9
Between the side boundary and the boundary of the light-scattering / reflecting portion forming area 4 on the side of the linear light source 2, almost no light is emitted to the surface of the light guide plate 1 due to the scattering and reflection in the light-scattering / reflecting portion 3. The distance between the line light source 2 side boundary of the light-scattering / reflecting portion forming region 4 and the line light source 2 side boundary of the effective display region 9 is the effective display region 9
And the light guide plate 1 may be appropriately determined within a range of 10 to 100% of the plate thickness of the light guide plate 1 on the side of the linear light source 2, depending on conditions such as a positional relationship between the light guide plate 1 and the width of the transparent adhesive layer 8 described later. ,
When the material thickness of the light guide plate 1 on the side of the linear light source 2 is 4 mm, 0.4 to 4 mm is preferable.

A back reflector 7 is arranged on the surface of the light guide plate 1 on which the light scattering reflector 3 is provided, and the light guide plate 1 and the back reflector 7 are arranged.
And are directly bonded by the transparent adhesive layer 8 on the line light source 2 side from the effective display area 9.

The back reflector 7 reflects the light that could not be returned into the light guide plate 1 in the light scattering reflector 3 to the light guide plate 1 side so that the light can be used efficiently. As the material of the back reflector 7, for example, the following materials are preferable. (1) A film or plate in which a white pigment is mixed in a resin. (2) White painted or white printed aluminum plate. (3) A metal plate having a mirror surface, a metal foil such as aluminum, or a film or plate obtained by vapor deposition of a metal such as aluminum or silver.

As the transparent adhesive layer 8, a double-sided tape, a screen-printed adhesive, an adhesive, a fixing agent, or the like is used. Adhesives include urethane-based and epoxy-based resins. Examples of the adhesive include resins such as rubber-based, acrylic-based, and silicon-based resins. An ultraviolet curable resin is used as the fixing agent. Further, by setting the width of the transparent adhesive layer 8 to a narrow range of 2 mm or less, the outer dimensions of the light guide plate 1 can be brought close to the dimensions of the effective display area 9.

Although the surface emitting device shown in FIG. 1 has been described above, the present invention is not limited to this. For example, instead of directly bonding the back reflector 7 to the light guide plate 1, the light guide plate 1
The light diffusing plate 6 may be arranged on the surface of and the light guide plate 1 and the light diffusing plate 6 may be bonded to each other by the transparent adhesive layer 8 on the line light source 2 side of the effective display region 9 (see FIG. 2).

The light diffusing plate 6 is for diffusing the light emitted from the surface of the light guide plate 1 and smoothing the luminance distribution. For example, the following materials are preferable as the material of the light diffusion plate 6. (1) A film or plate coated with a light diffusing substance. (2) A film or plate having a light diffusing property by itself. (3) A milky white resin film or plate. The light diffusing plate 6 is arranged closer to the light guiding plate 1 than the light diffusing plate 6 is in close contact with the light guiding plate 1, so that total reflection is secured inside the light guiding plate 1. Light guide plate 1
There is little loss inside and light can be reflected sufficiently. The light diffusion plate 6 may be formed in a plurality of layers.

Further, instead of directly bonding the back surface reflection plate 7 to the light guide plate 1, the light source reflection plate 5 is arranged so as to cover the surface of the linear light source 2 opposite to the light guide plate 1, and one end of the light source reflection plate 5 is arranged. Is directly bonded to the surface of the light guide plate 1 by the transparent adhesive layer 8 on the line light source 2 side of the effective display area 9, and the other end is bonded to the back surface of the light guide plate 1 by the transparent adhesive layer 8 on the line light source 2 side of the effective display area 9. (See FIG. 3).

The light source reflection plate 5 reflects the light from the surface of the linear light source 2 opposite to the light guide plate 1 to the light guide plate 1 side so that the light can be used efficiently. As the material of the light source reflector 5, it is preferable to use the same material as the back reflector 7.
The distance between the linear light source 2 and the light source reflector 5 may be kept uniform by interposing a spacer between them.

Further, the surface emitting device of the present invention may be used by selecting two or more from the light source reflector 5, the light diffuser 6 and the back reflector 7. For example, in the surface emitting device shown in FIG. 4, the back reflector 7 is provided on the surface of the light guide plate 1 on which the light scattering reflector 3 is provided.
Are arranged, and the light guide plate 1 and the back reflector 7 are arranged in the effective display area 9
The linear light source 2 side is directly bonded by the transparent adhesive layer 8. Then, the light source reflection plate 5 is arranged so as to cover the surface of the linear light source 2 on the side opposite to the light guide plate 1, and one end of the light source reflection plate 5 is arranged on the line light source 2 side of the effective display area 9 by the transparent adhesive layer 8 to form the light guide plate. 1 is directly bonded to the front surface of the light guide plate 1, and the other end is bonded to the back surface of the light guide plate 1 via the back reflection plate 5 by the transparent bonding layer 8 on the line light source 2 side from the effective display area 9. Further, a light diffusion plate 6 is arranged on the surface of the light guide plate 1, and the light guide plate 1 and the light diffusion plate 6 are arranged.
Are bonded to the linear light source 2 side of the effective display area 9 by the transparent adhesive layer 8 via the light source reflection plate 5.

When two or more of the light source reflection plate 5, the light diffusion plate 6 and the back surface reflection plate 7 are selected for use in the surface emitting device, at least one of the selected ones is the light guide plate 1.
It need only be directly bonded to. Further, of the two or more selected from the light source reflection plate 5, the light diffusion plate 6 and the back surface reflection plate 7 and used in the surface light emitting device, those not directly bonded to the light guide plate 1 need only be arranged and not bonded. Good.

[0029]

The surface emitting device of the present invention, having the above structure, has the following effects.

That is, the light emitted from the linear light source to the transparent adhesive layer is scattered and reflected by the transparent adhesive layer, and a part thereof is emitted from the transparent adhesive layer on the surface of the light guide plate from the center side of the light guide plate. However, in the surface emitting device of the present invention, the line light source side boundary of the light scattering reflection portion forming region is closer to the center of the light guide plate than the line light source side boundary of the effective display region. Almost no light is emitted to the surface of the light guide plate due to the scattering reflection at the light scattering reflection portion between the boundary of the scattering reflection portion formation region and the linear light source side.

The light scattered and reflected by the transparent adhesive layer is not only emitted to the surface of the light guide plate, but also part of it is guided to the back of the light guide plate.

[0032]

[Example] A transparent acrylic resin plate having a length of 200 mm, a width of 140 mm, and a thickness of 4 mm is used as a light guide plate, and a tube length 21 is provided on one side of the light guide plate.
A cold cathode ray tube having a diameter of 0 mm and a diameter of 3 mm was arranged as a line light source.

A large number of dots are screen-printed on the back surface of the light guide plate using a matte ink containing silica in an acrylic resin to form a gradation pattern having a large area ratio at a position away from the line light source from the line light source side. The light-scattering / reflecting portion having the above is provided. At this time, the boundary of the light-scattering / reflecting portion forming area on the side of the linear light source was further 2 mm closer to the center side of the light guide plate than the boundary of the effective display area on the side of the linear light source, which was 4 mm away from the side surface on which the linear light source was arranged.

A white polyethylene terephthalate film (Toray E6
0L) is arranged as a back reflector, and the light guide plate and the back reflector are directly bonded on the line light source side from the effective display area by a transparent adhesive layer made of a double-sided tape.

Further, a light source reflection plate made of a silver vapor deposition film (GR38W manufactured by Kimoto Co.) is arranged so as to cover the surface of the line light source opposite to the light guide plate, and one end of the light source reflection plate is closer to the line light source than the effective display area. With the transparent adhesive layer consisting of double-sided tape, it is directly adhered to the light guide plate surface. Glued to.

Further, on the surface of the light guide plate, a resin film (100S manufactured by Kimoto Co., Ltd.) coated with a light diffuser is arranged as a light diffuser plate, and the light guide plate and the light diffuser plate are located closer to the linear light source than the effective display area. A transparent adhesive layer composed of a double-sided tape was adhered via the light source reflection plate to obtain a surface emitting device.

The surface emitting device obtained as described above is
The outer dimensions of the light guide plate are as close as possible to the dimensions of the effective display area, and uniform and high-luminance light emission can be obtained.

[0038]

Since the surface emitting device of the present invention has the above-described structure and operation, the following effects can be obtained.

That is, between the boundary of the effective display area on the line light source side and the boundary of the area on which the light scattering reflection portion is formed on the line light source side, almost no light is emitted to the surface of the light guide plate due to scattering reflection at the light scattering reflection portion. Therefore, even if the outer dimensions of the light guide plate are made as close as possible to the dimensions of the effective display area, the light-scattering / reflecting portion forming area is more uniform in light emission than the conventional surface emitting device in which the area is formed at least as large as the effective display area. Obtainable.

Further, the light scattered and reflected by the transparent adhesive layer is guided to the back of the light guide plate in addition to being emitted to the surface of the light guide plate, so that compared to the conventional surface emitting device using the black adhesive layer. Thus, high-luminance light emission can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a surface emitting device according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 4 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional surface emitting device.

5 is a diagram showing a luminance unevenness state of the surface emitting device of FIG.

FIG. 7 is a cross-sectional view showing a conventional surface emitting device.

[Explanation of symbols]

 1 Light Guide Plate 2 Line Light Source 3 Light Scattering Reflector 4 Light Scattering Reflector Forming Area 5 Light Source Reflecting Plate 6 Light Diffusing Plate 7 Back Reflecting Plate 8 Transparent Adhesive Layer 9 Effective Display Area 10 Brightness Uneven 11 Black Adhesive Layer

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[Procedure amendment]

[Submission date] February 13, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a surface emitting device according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 4 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional surface emitting device.

FIG. 6 is a diagram showing a luminance unevenness state of the surface emitting device of FIG. 2;

FIG. 7 is a cross-sectional view showing a conventional surface emitting device.

[Explanation of reference numerals] 1 light guide plate 2 line light source 3 light scattering reflection part 4 light scattering reflection part formation region 5 light source reflection plate 6 light diffusion plate 7 back reflection plate 8 transparent adhesive layer 9 effective display area 10 brightness unevenness 11 black adhesive layer

Claims (4)

[Claims] 1. A linear light source is disposed on a side surface of a transparent light guide plate having an outer size larger than an effective display area, a light scattering reflection portion is provided on a back surface of the light guide plate, and a light scattering reflection portion of the light guide plate is provided. The back light reflector is placed on the surface of the light guide plate, the light guide plate and the back light reflector are directly adhered to each other by the transparent adhesive layer on the line light source side of the effective display area, and the boundary of the line light source side of the effective display area is the line of the light guide plate. In the surface light emitting device near the side surface where the light source is arranged, the surface light emitting device is characterized in that the boundary of the light scattering reflection portion forming region on the line light source side is closer to the center of the light guide plate than the boundary of the effective display region on the line light source side. 2. A linear light source is arranged on a side surface of a transparent light guide plate having an outer size larger than an effective display area, a light scattering reflection section is provided on a back surface of the light guide plate, and a light diffusion plate is arranged on a surface of the light guide plate. The light guide plate and the light diffusion plate are directly adhered to each other by the transparent adhesive layer on the line light source side of the effective display area, and the line light source side boundary of the effective display area is close to the side surface where the line light source of the light guide plate is arranged. In the light-emitting device, a surface light-emitting device characterized in that a boundary of the light-scattering / reflecting portion forming area on the line light source side is closer to a center of the light guide plate than a boundary of the effective display area on the line light source side. 3. A linear light source is disposed on a side surface of a transparent light guide plate having an outer size larger than an effective display area, a light scattering reflection section is provided on a back surface of the light guide plate, and a surface of the linear light source opposite to the light guide plate. The light source reflection plate is arranged so as to cover the light guide plate and the light source reflection plate are directly adhered to each other by the transparent adhesive layer on the line light source side of the effective display area, and the boundary of the line light source side of the effective display area is the light guide plate. A surface light emitting device in which a line light source is arranged closer to the side surface, wherein a boundary of the light scattering reflection portion forming region on the line light source side is closer to the center of the light guide plate than a boundary of the effective display region on the line light source side. 4. The distance between the line light source side boundary of the light scattering reflection portion forming region and the line light source side boundary of the effective display region is 10 to 100% of the plate thickness of the light guide plate on the line light source side. 3. The surface emitting device according to any one of 3 above.