Illumination – Revolving
Reexamination Certificate
2001-05-11
2003-02-04
O'Shea, Sandra (Department: 2875)
Illumination
Revolving
C362S026000, C362S561000, C349S058000
Reexamination Certificate
active
06513944
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a backlight device, wherein it is easy to replace the tubular lamps of the backlight device.
2. Description of the Related Art
Backlight devices are widely used in liquid crystal displays (LCDs) and scanners. A backlight device has tubular lamps inside to generate light. The lamps need to be replaced when they burn out. U.S. Pat. No. 5,537,296 discloses a structure of a backlight device, the only one part that the backlight device of the burned liquid crystal displays need to replaced is the tubular lamp. Other elements besides the burned lamp are left without being replaced together. However, it is difficult for an operator to disassemble and assemble the backlight device for repairing the burned lamp. JP patent No. 4-104486 and 4-288526 simplify the structure of the backlight device for easy maintenance, wherein the burned lamp is drawn out from the side surface of the backlight device. However, when the friction applied to the lamp is great, it is difficult to draw out a tight tubular lamp.
FIG. 1A
is an exploded perspective diagram of a conventional backlight device, wherein the directions of top, bottom, left, right, front and rear are defined for easy description. The backlight device includes a first frame
1
, a diffuser
2
, a lighting guide
3
, a reflection sheet
4
, a second frame
5
, a back plate
6
and two lamp assemblies
7
. In the assembling operation, the back plate
6
and the second frame
5
are screwed together via screws
61
, and it looks like a box without a cover. Then, the reflection sheet
4
, lighting guide
3
and diffuser
2
are put in the box in sequence, with one laid over another. Grooves
51
are formed between the second frame
5
and the lighting guide
3
. The lamp assemblies
7
are inserted, from the right to the left, into the grooves
51
. Then, the second frame
5
is engaged with the first frame
1
by the engaging portions
52
to fix all of the elements
4
,
3
,
2
,
7
therebetween.
Referring to FIG.
1
B and
FIG. 2
, each lamp assembly
7
includes two fluorescent tubes
72
, a tube guard
71
covering the fluorescent tubes
72
, and a base
73
for fixing the fluorescent tubes
72
in the tube guard
71
. Light is emitted from the fluorescent tubes
72
to propagate in the lighting guide
3
in two paths: (1) Light
75
passes through the front surface of the lighting guide
3
and then propagates out from the diffuser
2
. (2) Light
76
passes through the rear surface of the lighting guide
3
, is scattered by protrusions
31
on the lighting guide
3
, is reflected by the reflection sheet
4
back to the lighting guide
3
, and then propagates out from the diffuser
2
. The protrusions
31
on the rear surface of the lighting guide
3
are used for scattering the light
76
. The diffuser
2
is provided to further scatter the light
76
so that the distribution of the light
76
out from the diffuser
2
is more uniform (without the diffuser
2
, the images of the protrusions
31
can still be observed by the user in front of the lighting guide
3
).
It is important that the distance between the fluorescent tubes
72
and the lighting guide
3
must be accurately kept, otherwise (a) the light emitted out from the upper portion and lower portion of the lighting guide
3
will be too strong due to the fluorescent tubes
72
are too close to the lighting guide
3
. (b)On the other hand, the light emitted out from the upper portion and lower portion of the lighting guide
3
will be poor due to the fluorescent tubes
72
are far away from the lighting guide
3
.
FIG. 3
is a front view of
FIG. 1A
, wherein the lighting guide
3
, the reflection sheet
4
, the second frame
5
and the back plate
6
are already assembled. Also, the diffuser
2
and the first frame
1
are not shown in FIG.
3
. In assembling operation, the lamp assemblies
7
are inserted into grooves
51
from the right to the left, wherein the grooves
51
is formed and disposed between the second frame
5
and the lighting guide
3
. In the disassembling operation, ordinary the lamp assemblies
7
are pulled out from the grooves
51
from the left to the right. The widths of the grooves
51
and those of the lamp assemblies
7
are well matched to keep the lamp assemblies
7
tight, therefore, it is difficult for an operator to assemble/disassemble the backlight device due to a great friction between the lamp assemblies
7
and the grooves
51
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a backlight device with easy maintained tubular lamps.
The backlight device of the present invention includes a frame, alighting guide and at least one lamp assembly. The frame has an inner surface. The lighting guide is disposed inside the frame. The lamp assembly is disposed inside the frame and beside the lighting guide. A gap is provided between the inner surface of the frame and the lamp assembly to decrease the friction between the lamp assembly and the frame, thereby facilitating the replacement of the tubular lamp.
REFERENCES:
patent: 5666172 (1997-09-01), Ida et al.
Au Optronics Corp.
Ladas & Parry
O'Shea Sandra
Ward John Anthony
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