Illumination – Revolving
Reexamination Certificate
1999-08-26
2001-10-30
Quach, Y. (Department: 2875)
Illumination
Revolving
C362S026000, C349S065000
Reexamination Certificate
active
06309081
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Industrial Field of the Invention
The present invention relates to a backlight unit which achieves considerably simple and easy replacement of a line light source, such as a fluorescent tube, that must maintain a predetermined positional relationship with respect to a light guide plate or the like, and relates to an electronic apparatus using the backlight unit.
2. Description of the Related Art
As is generally known, liquid crystal display apparatus are used in many display apparatus for use in information apparatus, such as notebook personal computers, because they feature light weight, thin profile, and low power consumption. In recent years, liquid crystal display apparatus having a backlight unit built therein have become dominant with improvements in brightness and colorization in liquid crystal display screens, and for other reasons. The backlight units are roughly classified into the direct-lighting type using a reflecting curtain or the like, and the edge-lighting type using a light guide plate. In most notebook personal computers and the like, edge-lighting type backlight units are adopted because of a strong demand for thinner profiles.
A description will now be given of the structure of a conventional edge-lighting type backlight unit. FIG.
6
(
a
) is a plan view showing the structure of the backlight unit, and FIG.
6
(
b
) is a side view thereof. As shown in these figures, in the edge-lighting type backlight unit, a fluorescent tube
10
is placed on the side of a light guide plate
20
, and is wrapped in a reflecting film
30
so that light emitted therefrom is effectively guided to the light guide plate
20
. The reflecting film
30
is made of, for example, a PET (polyethylene terephthalate) evaporated with a high-reflectance metal film of silver, aluminum, or the like, a simply white PET, or the like, and both ends thereof are adhered to the upper and lower (front and back) surfaces of the light guide plate
20
by double-sided adhesive tapes
40
.
A diffusing plate
50
and a reflecting plate
60
are provided on the upper and lower surfaces of the light guide plate
20
, respectively, and are adhered by a tape
70
or the like to the side portion of the light guide plate
20
opposite from the side portion where the fluorescent tube
10
is placed. The diffusing plate
50
and the reflecting plate
60
are not adhered onto the entire surface of the light guide plate
20
, but only to one surface thereof in order to prevent warp resulting from the difference in coefficients of thermal expansion.
In general, the fluorescent tube
10
has the shortest service life among the respective components of the liquid crystal display apparatus. For this reason, there has been a demand for a structure that allows the fluorescent tube
10
to be simply and easily replaced.
In the conventional backlight unit shown in the figure, however, since the reflecting film
30
is adhered to the light guide plate
20
, it is impossible to simply and easily replace the fluorescent tube
10
. That is, it is significantly troublesome to perform operations of peeling the reflecting film
30
off the light guide plate
20
, replacing the fluorescent tube
10
, and subsequently adhering the reflecting film
30
again to the light guide plate
20
. Moreover, the reflecting film
30
may be creased during replacement.
When the fluorescent tube
10
is placed close to the light guide plate
20
or the reflecting film
30
, abnormalities may occur in lighting characteristics. For this reason, spacers SP or the like are sometimes provided to place the fluorescent tube
10
in a predetermined positional relationship with respect to the side portion of the light guide plate
20
and the reflecting surface of the reflecting film
30
. This further complicates the operation of replacing the fluorescent tube
10
.
The present invention has been made in view of the above problems, and it is accordingly an object of the present invention to provide a backlight unit which achieves considerably simple and easy replacement of a fluorescent tube that must maintain a predetermined positional relationship with respect to a light guide plate or the like, and to provide an electronic apparatus using the backlight unit.
SUMMARY OF THE INVENTION
In order to achieve the above object, the present invention comprises a line light source for emitting light, a light guide plate for making the light from the line light source uniform, and a gripper for covering the line light source with a reflective surface and for gripping an end portion of the light guide plate.
According to this structure, the gripper covers the line light source, such as a fluorescent tube, with a reflective surface, and grips the end portion of the light guide plate. Since this facilitates attachment and detachment of the gripper to the light guide plate, it is possible to simply and easily replace the line light source such as a fluorescent tube.
In this case, it is preferable that the light guide plate and the gripper be provided with a positioning mechanism for forming a predetermined positional relationship therebetween. As the positioning mechanism, it may be possible to form a projection in one of the light guide plate and the gripper and to form a recess or a hole in the other so as to be engaged with the projection, or to form a cutout portion in the light guide plate and to shape the gripper so as to engage with the cutout portion.
In the case in which the light guide plate and the gripper are provided with the positioning mechanism for forming a predetermined positional relationship therebetween, it is preferable that the line light source be covered at both ends with a spacer having a diameter that is larger than the outer diameter of the line light source and is smaller than the inner diameter of the gripper for covering the line light source. According to this structure, the gripper is placed in a predetermined positional relationship with respect to the light guide plate, and the line light source is also placed in a predetermined positional relationship with the respect to the gripper and the light guide plate. In this case, it is most preferable that the outer diameter of the spacer be substantially equal to the inner diameter of the gripper. Furthermore, when the spacer is formed by a bracket for protecting a lead portion of the line light source, it can also function as a mechanism for positioning the line light source.
An electronic apparatus of the present invention comprises a line light source for emitting light, a light guide plate for making the light from the line light source uniform, a gripper for covering the line light source with a reflective surface and for gripping an end portion of the light guide plate, and a liquid crystal display panel including liquid crystal sandwiched between a pair of substrates, the liquid crystal display panel being disposed on the emitting side of the light guide plate.
REFERENCES:
patent: 5211464 (1993-05-01), Bohmer
patent: 5497293 (1996-03-01), Noguchi et al.
patent: 5558420 (1996-09-01), Oki et al.
patent: 5590947 (1997-01-01), Kidd, Jr.
patent: 5815227 (1998-09-01), Lu
Harness & Dickey & Pierce P.L.C.
Quach Y.
Seiko Epson Corporation
LandOfFree
Backlight unit and electronic apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Backlight unit and electronic apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Backlight unit and electronic apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2608448