JPH0736039A - L-shaped linear light source type surface light emission device - Google Patents

Abstract

PURPOSE:To obtain an L-shaped linear light source type surface light emission device high in brightness low in power consumption and hardly causing unevenness of brightness. CONSTITUTION:In an edge light system surface light emission device arranged with a linear light source on the side surfaces of a transparent light transmission plate 1 and provided with a light diffusion and transmission part of the rear surface of the plate 1, the linear light source is the L-shaped linear light source 2 extending over two adjacent side surface of the plate 1, and side reflection plates 4 are arranged on two side surfaces of the plate 1 where the light source 2 is not arranged. Besides, the light diffusion and transmission part is provided so that the area ratio thereof becomes the maximum at a point which exists at the corner part of the plate 1 on the reflection plate 4 side or on the more center side of the plate 1 than the corner part and where the brightness of the linear light source is minimized and becomes smaller as it is away from the point. Then, the parts of the light diffusion and transmission part where the area ratio is identical exist in a circumference state or in a circular-arc state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an L-shaped linear light source type surface emitting device which has high brightness, low power consumption, and less uneven brightness.

[0002]

2. Description of the Related Art Conventionally, as a thin edge-light type surface emitting device used for a backlight of a liquid crystal panel, a straight line light source is arranged on one side surface of a light guide plate, and a light diffusion / transmission part is provided on the back surface of the light guide plate. And a side surface reflector is arranged on the other side surface opposite to the side surface on which the straight line light source is arranged. The light diffusion / transmission part has an area ratio increasing with distance from the side surface on which the linear light source is arranged, and portions having the same area ratio are provided so as to be present in a straight line parallel to the side surface on which the linear light source is arranged. By the light diffusion / transmission part, the light entering the light guide plate from the linear light source is uniformly emitted from the surface of the light guide plate.

However, the surface emitting device in which a straight line light source is arranged on one side surface of the light guide plate has low brightness. Therefore, in order to increase the brightness of the surface light emitting device, it is necessary to introduce light from two adjacent side surfaces of the light guide plate. In that case, power consumption can be reduced by using an L-shaped linear light source extending over two adjacent side surfaces of the light guide plate, rather than disposing one linear light source for one side surface.

[0004]

However, when the L-shaped linear light source 2 extending over two adjacent side surfaces of the light guide plate 1 is used in a surface light emitting device, the light diffusion / transmission part on the back surface of the light guide plate 1 is arranged with the linear light source. The area ratio increases as the distance from the side surface increases, and a portion having the same area ratio is provided so as to exist in a straight line parallel to the side surface on which the linear light source 1 is arranged. In FIG. 6 and FIG. 7, the straight lines and the numbers related to the surface of the light guide plate show the change of the area ratio.). In the case of FIG. 6, since the side reflectors 4 are arranged on the two side surfaces of the light guide plate 1 on which the L-shaped linear light source 3 is not arranged,
The brightness of the linear light source is the smallest at the point that is located closer to the center of the light guide plate 1 than the corner of the light guide plate 1 on the side of the side reflector 4, and the area ratio of the light diffusion / transmission part at this point is maximized to compensate for the lack of brightness. It is provided. When the amount of light reflected by the side reflector 4 is small, the area ratio of the light diffusion / transmission part depends on the side reflector 4 of the light guide plate 1.
It becomes maximum at the middle position of the side surface.

Therefore, since the portion having the same area ratio of the light diffusing / transmitting portion exists in a straight line parallel to the side surface on which the linear light source is arranged, light interference occurs where the portions having the same area ratio contact at right angles. There is a problem that the degree is extremely increased and light stripes 7 are generated on the light exit surface of the light guide plate 1 (see FIGS. 8 and 9).

Therefore, an object of the present invention is to solve the above problems and to provide an L-shaped linear light source type surface light emitting device which has high brightness, low power consumption, and less uneven brightness.

[0007]

In order to achieve the above object, the present invention provides an edge light system in which a linear light source is arranged on the side surface of a transparent light guide plate and a light diffusion / transmission part is provided on the back surface of the light guide plate. In the surface emitting device, the linear light source is an L-shaped linear light source extending over two adjacent side surfaces of the light guide plate, and the side reflectors are arranged on the two side surfaces of the light guide plate on which the L-shaped linear light source is not arranged. The side diffuser side corner portion or the light diffusing and transmitting portion is provided so that the area ratio becomes smaller as the distance from this point becomes maximum with the point where the brightness of the linear light source existing on the center side of the light guide plate from this position becomes the minimum, L so that the parts of the same area ratio of the light diffusion / transmission part exist in the shape of a circle or arc.
This is a configuration of a linear light source type surface emitting device.

Further, according to the present invention, in a surface emitting device of an edge light system in which a line light source is arranged on a side surface of a transparent light guide plate and a light diffusion / transmission part is provided on a back surface of the light guide plate, the line light source is adjacent to the light guide plate. This L-shaped line light source covers two sides
Two linear light sources are arranged so as to surround the four sides of the light guide plate, and the point where the brightness of the line light source in the center of the light guide plate is the smallest is the maximum, and the area ratio becomes smaller as the distance from this point decreases. An L-shaped linear light source type surface light emitting device is configured such that a diffuse transmission portion is provided and portions of the light diffusion transmission portion having the same area ratio are present in a circumferential shape or an arc shape.

In the above structure, the area ratio of the light diffusing and transmitting portion may be set to be larger in the vicinity of both ends of the L-shaped linear light source than in the vicinity of the bent portion of the L-shaped linear light source.

In the above structure, the back reflector may be arranged on the back surface of the light guide plate on which the light diffusion / transmission part is formed.

Further, in the above structure, a light diffusing plate may be arranged on the surface of the light guide plate.

The present invention will be described in more detail with reference to the drawings. 1 is a plan view showing an embodiment of a change in area ratio of a light diffusion / transmission part according to the present invention, FIG. 2 is a sectional view taken along the line AA of the L-shaped linear light source type surface light emitting device of FIG. 1, and FIG. FIG. 4 and FIG. 5 are BB cross-sectional views of an L-shaped linear light source type surface emitting device, and FIGS. Reference numeral 1 is a light guide plate, 2 is an L-shaped linear light source, 3 is a light diffusion / transmission part, 4 is a side reflector, 5 is a back reflector, and 6 is a light diffuser.

The light guide plate 1 is preferably a transparent rectangular plate material having a thickness of about 1 to 30 mm. Further, it is preferable that the side surface of the light guide plate 1 is polished so as to be a smooth surface. As a material for the light guide plate 1, it is preferable to use a resin such as an acrylic resin, a polycarbonate resin, a polyvinyl chloride resin, or glass.

A cathode ray tube such as a hot cathode ray tube or a cold cathode ray tube is used as one or two L-shaped line light sources 2. Further, a curved reflection plate is arranged so as to cover a portion of the L-shaped linear light source 2 that does not face the light guide plate 1, and the light from the L-shaped linear light source 2 can be efficiently used by the mirror surface inside thereof. May be.

On the back surface of the light guide plate 1, the point where the brightness of the linear light source is the smallest is set as the maximum, and the area ratio becomes smaller as the distance from this point increases, and portions having the same area ratio are present in a circular or arc shape. The light diffusing / transmitting portion 3 is provided at When the amount of reflection by the side reflector 4 is small, the point where the area ratio of the light diffusion / transmission part 3 is maximum exists at the corners of the light guide plate 1 on the side reflector 4 side (see FIG. 4, regarding the surface of the light guide plate). Curves and numbers show changes in area ratio.). Further, when there is a large amount of reflection by the side reflection plate 4, the point where the area ratio of the light diffusion / transmission part 3 becomes maximum exists closer to the center of the light guide plate 1 than the corner of the side reflection plate 4 (see FIG. 1). Curves and numbers related to the surface of the light plate show the change in area ratio. When two L-shaped linear light sources 2 are arranged so as to surround the four side surfaces of the light guide plate 1, the light diffusion plate 3 has the maximum area ratio.
It exists in the center (see FIG. 5, curves and numbers related to the surface of the light guide plate show changes in area ratio). The light reaching the light diffusion / transmission part 3 from the L-shaped linear light source 2 is diffused here and is directed to the front side of the light guide plate 1, or the direction of the light guide plate 1 further away from the L-shaped linear light source 2 is detected. Head in the direction.

Further, by making the area ratio of the light diffusing and transmitting portion 3 larger in the vicinity of both ends of the L-shaped linear light source 2 than in the vicinity of the bent portion of the L-shaped linear light source 2, The low brightness can be compensated.

The gradation pattern of the light diffusion / transmission part 3 can be formed by a large number of fine dots.
The dots forming the light diffusing and transmitting portion 3 are, for example, circular, and the area ratio can be changed by changing the diameter dimension of the dots so as to change the density of printing dots. The light diffusion / transmission part 3 is not limited to a circular dot, and may be formed of a dot of any shape. Further, not only dots but also stripes or the like may be used. Light diffusion transmission part 3
Is an ink containing a particulate transparent substance having a refractive index substantially equal to or lower than that of the light guide plate 1 such as calcium carbonate or silica, and is used in a printing method such as gravure printing, offset printing, screen printing, or a transfer method. It may be formed by means.

When there is one L-shaped linear light source 2, a side reflector 4 may be formed on the side surface of the light guide plate 1 where the L-shaped linear light source 2 is not arranged. As the side reflector 4, (1)
White polyethylene terephthalate film, (2) white painted or white printed aluminum plate, (3) metal plate or metal foil with mirror surface, metal evaporated film or plate,
(4) white ink coating or printing layer, (5) vapor deposition layer,
(6) A white resin layer or the like can be used.

Further, as shown in FIG. 3, a back reflector 5 may be arranged on the back surface of the light guide plate 1. As the back reflector 5, (1) white polyethylene terephthalate film, (2)
A white painted or white printed aluminum plate or the like can be used.

The side reflector 4 or the rear reflector 5
Can be replaced with a surface light source device case (not shown) whose inner surface is coated with white paint.

The light diffusion plate 6 may be arranged on the front side of the light guide plate 1 so as not to be in close contact with it. As the light diffusing plate 6, it is possible to use (1) a light diffusing film in which a light diffusing substance is applied, (2) a film having diffusivity itself, (3) a milky white resin plate, or the like.

[0022]

The L-shaped linear light source type surface emitting device of the present invention has the following actions since it is constructed as described above.

That is, a part of the light entering the transparent light guide plate from the L-shaped linear light source has the same incident angle and reflection angle at a portion where the light diffusion / transmission part is not provided and repeats total reflection. Guided to the back of the light board. On the other hand, the remaining light is scattered at a place where the diffusion / transmission part is provided, and is directly guided to the front surface side of the light guide plate, or is indirectly reflected after being reflected by the back reflector on the back surface of the light guide plate.

At this time, since the area ratio of the light diffusing and transmitting portion is small in the portion away from the point where the brightness of the linear light source is the smallest, little light is guided to the surface side of the light guide plate, and most of the light is in the light guide plate. Be guided deep inside.

In the vicinity of the point where the brightness of the linear light source is the smallest, since the area ratio of the light diffusing and transmitting portion is large, most of the light is guided to the surface side of the light guide plate and is guided to the back of the light guide plate. Is few.

[0026]

EXAMPLE An example of an L-shaped linear light source type surface emitting device according to the present invention will be described below. A transparent acrylic plate with a long side of 90 mm, a short side of 70 mm, and a thickness of 4 mm is used as a light guide plate, and an L-shaped long side of 90 mm, an L-shaped short side of 70 mm, and a diameter of 3 mm of a hot cathode ray tube are L-shaped across two adjacent sides. One linear light source is arranged.

A white reflector (E60L manufactured by Toray Industries, Inc.) was disposed as a side reflector on two sides of the light guide plate on which the L-shaped linear light source was not disposed.

The back side of the light guide plate has a long side of 80 mm and a short side of 60 mm.
The maximum area is the point where the brightness of the linear light source existing on the side reflector side corner of the light guide plate is the maximum, and the area ratio becomes smaller as the distance from this point increases, and the area with the same area ratio is circled. It was provided by screen printing using a light-scattering ink so as to exist in a circular shape or an arc shape. The area ratio of the light diffusion / transmission part is 80% at the maximum point, 50% near the bent part of the L-shaped line light source, and 60% at the area ratio near the end on the short side of the L-shaped line light source. , 70% in the area ratio near the end on the long side of the L-shaped linear light source.

A white reflector (E6 manufactured by Toray Industries, Inc.) is also used as a back reflector on the back surface of the light guide plate on which the light diffusion / transmission part is formed.
0L) and a light diffusion film (100SH manufactured by Kimoto Co., Ltd.) as a light diffusion plate on the surface of the light guide plate.

The L-shaped linear light source type surface emitting device having such a structure has a high brightness of 4500 cd / m ² and a low power consumption of 2.4 w, and has a uniformity of brightness of 90% and uneven brightness. there were.

[0031]

The L-shaped linear light source type surface light emitting device of the present invention comprises:
With the above configuration and operation, the following effects can be obtained.

That is, since the portions of the same area ratio of the light diffusion / transmission portion exist in the circumferential shape or the arc shape, the portions of the same area ratio do not contact each other at a right angle, and the degree of light interference increases extremely. No light streaks are generated on the light exit surface of the light plate. Therefore, it is possible to obtain surface light emission with uniform brightness without uneven brightness, and to have high brightness and low power consumption.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a change in area ratio of a light diffusion / transmission part according to the present invention.

2 is a cross-sectional view taken along the line AA of the L-shaped linear light source type surface emitting device of FIG.

FIG. 3 is a BB cross-sectional view of the L-shaped linear light source type surface emitting device of FIG.

FIG. 4 is a plan view showing another embodiment of the area ratio change of the light diffusion / transmission part according to the present invention.

FIG. 5 is a plan view showing another embodiment of the area ratio change of the light diffusion / transmission part according to the present invention.

FIG. 6 is a plan view showing an area ratio change of a conventional light diffusing and transmitting portion applied to one L-shaped linear light source.

FIG. 7 is a plan view showing an area ratio change of a conventional light diffusion / transmission part applied to two L-shaped linear light sources.

FIG. 8 is a plan view showing uneven brightness generated by the light diffusion / transmission part of FIG. 6;

9 is a plan view showing uneven brightness generated by the light diffusion / transmission part of FIG. 7. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 2 L-shaped linear light source 3 Light diffusion / transmission part 4 Side reflector 5 Back reflector 6 Light diffuser 7 Light streaks

Claims (5)

[Claims] 1. A linear light source is arranged on a side surface of a transparent light guide plate,
In an edge-light type surface emitting device in which a light diffusion / transmission part is provided on the back surface of a light guide plate, the line light source is an L-shaped line light source extending over two adjacent side surfaces of the light guide plate, and no L-shaped line light source is arranged. Side reflectors are arranged on two sides of the light guide plate, and the point where the brightness of the line light source existing on the side reflector side corner of the light guide plate or on the center side of the light guide plate from this position is the smallest is the maximum, and as the distance from this point increases. An L-shaped linear light source type surface light-emitting device characterized in that a light diffusion / transmission part is provided so that the area ratio becomes small, and portions of the light diffusion / transmission part having the same area ratio exist in a circumferential shape or an arc shape. 2. A linear light source is arranged on a side surface of a transparent light guide plate,
In an edge-light type surface emitting device in which a light diffusion / transmission part is provided on the back surface of a light guide plate, the line light source is an L-shaped line light source extending over two adjacent side surfaces of the light guide plate, and the L-shaped line light source is the light guide plate. Two pieces are arranged so as to surround the four side surfaces, and the light diffusion and transmission part is provided so that the area ratio becomes smaller as the distance from this point becomes the maximum, with the point where the brightness of the linear light source existing in the center of the light guide plate is the maximum. L having the same area ratio portion of the diffuse transmission portion in a circular shape or an arc shape.
A linear light source type surface emitting device. 3. The L-shape of claim 1 or 2, wherein the area ratio of the light diffusion / transmission part is larger in the vicinity of both ends of the L-shaped linear light source than in the vicinity of the bent part of the L-shaped linear light source. Linear light source type surface emitting device. 4. The L-shaped linear light source type surface emitting device according to claim 1, wherein a back reflector is arranged on the back surface of the light guide plate on which the light diffusion / transmission part is formed. 5. The L-shaped linear light source type surface emitting device according to claim 1, wherein a light diffusing plate is arranged on the surface of the light guide plate.