Illumination – Revolving
Patent
1995-04-27
1998-07-07
Cariaso, Alan
Illumination
Revolving
362 26, 362327, 362330, F21V 800
Patent
active
057757917
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a surface emission apparatus used for illuminating, from the back, a liquid crystal display panel or the like serving as a body to be illuminated in, e.g., a liquid crystal television, a potable personal computer, or a wordprocessor.
BACKGROUND ART
Conventionally, in a surface emission apparatus, in order to guide light emitted from a light source to a light-emitting surface, light from the light source is made to be incident on a light-guide plate and emerges toward the light-emitting surface. As the technique to form such a light-guide plate by subjecting a surface of the light-guide plate opposing the light-emitting surface to hairline formation so as to randomly reflect light incident on this surface, thereby efficiently guiding light from the light source to the light-emitting surface, one disclosed in, e.g., Japanese Patent Publication No. 58-17957 is known.
In recent years, however, the size of, e.g., the liquid crystal panel, is increasing, and the area of the light-emitting surface of a surface emission apparatus which serves as the back light of the liquid crystal panel is also increasing. On the other hand, a low-profile surface emission apparatus is demanded to obtain a compact, lightweight system in which a liquid crystal panel or the like is incorporated. When the surface emission apparatus is increased in size at a low profile, in a surface emission apparatus using a conventional light-guide plate, a portion of the light-emitting surface closer to the light source is bright while a portion thereof farther from the light source is dark since light does not easily reach there, leading to a non-uniformity in brightness of the light-emitting surface. Thus, it is difficult to obtain light emission with entirely uniform brightness.
As an improvement over this drawback in the surface emission apparatus, a technique disclosed in, e.g., Japanese Patent Laid-Open No. 2-126501 is known, which uniforms the brightness of the light-emitting surface by printing an ink dot pattern on a surface of the light-guide plate opposing the light-emitting surface such that the farther from the light source, the higher the dot density.
When an ink or the like is printed in this manner, however, it is difficult to completely eliminate absorption of light by the ink itself, leading to a decrease in emission efficiency. Also, since a step of printing the ink is needed, the manufacturing process is complicated, leading to an increase in cost.
The present invention has been made in view of the above conventional techniques, and has as its object to provide a surface emission apparatus capable of uniformly emitting light of the light source by uniformly emitting light toward the entire light-emitting surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a surface emission apparatus according to an embodiment of the present invention;
FIG. 2 is a plan view of the surface emission apparatus;
FIG. 3 is an enlarged view of the bottom surface of a light-guide plate;
FIG. 4 is a sectional view showing a projecting portion formed on the bottom surface of the light-guide plate shown in FIG. 3;
FIG. 5 is a sectional view showing a light-guide plate according to another embodiment of the present invention; and
FIGS. 6(A) and 6(B) are sectional views showing projecting portions formed on the bottom surfaces of light-guide plates according to other embodiments.
DISCLOSURE OF INVENTION
In order to achieve the above object, according to the present invention, there is provided a surface emission apparatus for causing light, emitted from a light source arranged on a side of a light-emitting surface thereof, to emerge from the light-emitting surface, comprising a transparent light-guide plate in which reflecting shape portions formed with small projecting portions are arranged on a bottom surface portion thereof opposing the light-emitting surface such that a density of the projecting portions is gradually increased in accordance with a distance from the light so
REFERENCES:
patent: 4890201 (1989-12-01), Toft
patent: 4985809 (1991-01-01), Matsui et al.
patent: 5070431 (1991-12-01), Kitazawa et al.
patent: 5377084 (1994-12-01), Kojima et al.
International Search Report for International Application No. PCT/JP93/01238.
Nakamura Shigekazu
Yoshikawa Yukio
Cariaso Alan
Copal Company Limited
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