Illumination – Revolving
Reexamination Certificate
1998-03-17
2001-09-04
Quach, Y. (Department: 2875)
Illumination
Revolving
C362S026000, C362S027000
Reexamination Certificate
active
06283602
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a lighting device using a light guide. The invention is also concerned with a liquid crystal display unit using the above type of lighting device. The invention further pertains to electronic equipment using the above type of liquid crystal display unit.
2. Discussion
Liquid crystal display units are being widely used as visible information displays for various types of electronic equipment, such as mobile cellular telephones, video cameras, etc. In this type of liquid crystal display unit, the orientations of liquid crystals are controlled to modulate light, thereby displaying characters, numbers, and other visible information. The liquid crystal display unit is generally formed in the following manner. A driver IC is attached to a liquid crystal panel so as to form a liquid crystal module. Further, a lighting device and a reflector are fixed to the liquid crystal module.
Hitherto, as the foregoing lighting device, the lighting device shown in
FIG. 10
is known which has a planar light guide
101
and point-source lights
102
which are positioned to face a light incident surface
101
a
of the light guide
101
. In this conventional device, the light emitted from the point-source lights
102
is diverged by lenses
103
, respectively, and the diverged light then radiates in a planar form from a light emitting surface
101
b
of the light guide
101
.
In the above known type of lighting device, however, the area in which the light emitted from the point-source lights
102
can be guided is restricted to predetermined angular areas A. A sufficient luminance level of light can be obtained in the areas A, but not in the portions outside the areas A. As a result, the overall light emitting surface
101
b
cannot emit light with a uniform luminance level.
In view of the above problem, it is an object of the present invention to provide a lighting device in which the light having a uniform luminance level can emit from the overall planar light emitting surface of a light guide when the light is applied to the light guide from point-source lights.
SUMMARY OF THE INVENTION
In order to achieve the above object, according to one aspect of the present invention, there is provided a lighting device comprising a point-source light for emitting light in a point-like form, and a planar light guide for guiding the light from the point-source light and radiating the guided light from a planar light emitting surface in a planar form, the lighting device being characterized in that a linear light guide is disposed between the point-source light and the planar light guide so as to convert the light from the point-source light into linear light and radiate the linear light to the planar light guide. According to this lighting device, since the linear light rather than the point-like light is incident on the light incident surface of the planar light guide, the light having a uniform luminance level can be obtained on the overall planar light emitting surface of the planar light guide.
With the above configuration, the linear light guide and the planar light guide may be separately formed, and then, the light emitting surface of the linear light guide and the light incident surface of the planar light guide may be brought into contact with each other. Alternatively, the linear light guide and the planar light guide may be integrally formed of the same member. In this case, one cross-sectional surface of the same member may potentially be used as both the light emitting surface of the linear light guide and the light incident surface of the planar light guide.
In the foregoing configuration, the linear light guide may be formed in a rod-like shape provided with a light emitting surface in a position opposedly facing a light incident surface of the planar light guide. At this time, the point-source light may be positioned to opposedly face at least one of the lateral surfaces adjacent to the light emitting surface of the linear light guide. Moreover, a light reflecting member for guiding the light from the point-source light to the light emitting surface of the linear light guide may be provided on a surface other than the light emitting surface of the linear light guide. The light reflecting member may be formed of any one of, for example, a prism, a dot pattern having a light reflecting color, and a light reflecting sheet. The light reflecting color is generally white, but may be another color as long as it can reflect the light.
If the light reflecting member is provided for the linear light guide, the surface on which the light reflecting member is disposed may be preferably inclined in a direction toward the point-source light. It is thus possible to efficiently guide the light radiated from the point-source light to the planar light guide.
According to another aspect of the present invention, there is provided a liquid crystal display unit comprising a liquid crystal panel and a lighting device attached to the liquid crystal panel. The lighting device has a point-source light for emitting light in a point-like form, and a planar light guide for guiding the light from the point-source light and radiating the guided light from a planar light emitting surface in a planar form. A linear light guide is disposed between the point-source light and the planar light guide so as to convert the light from the point-source light into linear light and radiate the linear light to the planar light guide. In the liquid crystal display unit, as well as the foregoing lighting device, the linear light rather than the point-like light is incident on the light incident surface of the planar light guide, thereby making it possible to obtain the light having a uniform luminance level on the overall planar light emitting surface of the planar light guide.
According to a further aspect of the present invention, there is provided electronic equipment comprising the foregoing liquid crystal display unit. The electronic equipment includes at least the above liquid crystal display unit, a power supply unit for supplying power to the liquid crystal display unit, and a controller for controlling the operation of the liquid crystal display unit. Various types of electronic equipment, for example, mobile cellular telephones and video cameras, may be considered.
REFERENCES:
patent: 3740540 (1973-06-01), Takeichi et al.
patent: 5375043 (1994-12-01), Tokunaga
patent: 5506929 (1996-04-01), Tai et al.
patent: 5915855 (1999-06-01), Murase et al.
patent: 4329914 A1 (1995-03-01), None
patent: 0560605 A1 (1993-09-01), None
patent: 0751340 A3 (1997-01-01), None
patent: 0800036 A1 (1997-10-01), None
patent: WO 96/17207 (1996-06-01), None
Kawaguchi Yoshito
Kobayashi Shigeo
Harness & Dickey & Pierce P.L.C.
Quach Y.
Seiko Epson Corporation
LandOfFree
Lighting device, liquid crystal display unit, and electronic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lighting device, liquid crystal display unit, and electronic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lighting device, liquid crystal display unit, and electronic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2530000