Illumination – Light fiber – rod – or pipe – Illuminating or display apparatus
Reexamination Certificate
2002-07-29
2003-09-09
Tso, Laura K. (Department: 2875)
Illumination
Light fiber, rod, or pipe
Illuminating or display apparatus
C362S035000
Reexamination Certificate
active
06616316
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spread illuminating apparatus used as an illuminating means for a liquid crystal display, and more particularly to a frame of such a spread illuminating apparatus.
2. Description of the Related Art
A liquid crystal display (hereinafter referred to as “LCD”) featuring low profile, small occupied volume and light-weight has been extensively used in various electric products such as cellular phones and personal computers, and the demand therefor has been increasing. Since a liquid crystal used for the LCD does not emit light by itself, the LCD requires a separate illuminating means when used in dark places where sunlight or room light is not satisfactorily available. The illuminating means is demanded to be small in size and low in power consumption, and recently a spread illuminating apparatus of side light type (light conductive plate type) is often used as the illuminating means.
FIG. 5
shows an exploded perspective view showing an embodiment of a conventional spread illuminating apparatus of side light type having a frame (housing).
As shown in the figure, a spread illuminating apparatus
1
′ generally comprises a light conductive plate
2
made of a light-transmissible material, lamps
5
a
and
5
b
comprising respective light conductive bars
3
a
and
3
b
and respective spot-like light sources
4
a
and
4
b
and disposed respectively along side surfaces
8
and
18
of the light conductive plate
2
, an FPC (flexible printed circuit)
6
having the light sources
4
a
and
4
b
mounted thereon, light reflection members (reflectors)
13
a
and
13
b
covering the lamps
5
a
and
5
b
, respectively, and frames
7
a
and
7
b
covering the peripheral portion of the spread illuminating apparatus
1
′ comprising the above-mentioned members. Lights emitted from the lamps
5
a
and
5
b
enter the light conductive plate
2
and are reflected therein so as to irradiate an LCD L disposed under the light conductive plate
2
.
A light reflection pattern
29
is formed on a top surface (observation surface)
25
of the light conductive plate
2
so that the lights having entered the side surfaces
8
and
18
(hereinafter referred to also as “incidence surfaces”) are reflected therein and emitted through a bottom surface
26
in a uniform spread manner in the direction of the LCD L. The light reflection pattern
29
comprises a plurality of grooves
27
and a plurality of flat portions
28
adjacent thereto, and is oriented parallel to the longitudinal direction of the light conductive bars
3
a
and
3
b
. The light reflection pattern
29
may comprise only grooves continuously formed. The grooves may be oriented so as to have a predetermined angle with respect to the longitudinal direction of the light conductive bars. With the light reflection pattern thus configured, the lights having entered the light conductive plate
2
are reflected in a substantially uniform manner at the entire top surface of the light conductive plate
2
, and irradiates the LCD L disposed under the light conductive plate
2
.
The lamps
5
a
and
5
b
comprise the respective light conductive bars
3
a
and
3
b
and the respective light sources (for example, light emitting diodes)
4
a
and
4
b
. Optical path conversion means
12
a
and
12
b
are formed on respective one side surfaces of the light conductive bars
3
a
and
3
b
, and the light sources
4
a
and
4
b
are disposed close to respective one ends of the light conductive bars
3
a
and
3
b
. The light sources
4
a
and
4
b
are mounted on the FPC
6
and fixed thereto by soldering. The light reflection members
13
a
and
13
b
are disposed so as to cover respectively the light conductive bars
3
a
and
3
b
and two opposing sides of the light conductive plate
2
when the spread illuminating apparatus
1
′ is assembled.
The light reflection members
13
a
and
13
b
are provided in order to efficiently guide the lights emitted from the light sources
4
a
and
4
b
into the light conductive plate
2
, to prevent the light conductive bars
3
a
and
3
b
from getting damaged due to a contact with other members, or to enhance a dust-proof effect for the light conductive bars
3
a
and
3
b
. The light reflection members
13
a
and
13
b
are shaped substantially like U-letter in section, and cover the longitudinal surfaces of the light conductive bars
3
a
and
3
b
except a surface facing the light conductive plate
2
. The reflection members
13
a
and
13
b
are structured such that a film evaporated with a metal such as silver, or a white film is attached to a hard resin member or that a metal plate such as an aluminum plate or a stainless steel-plate is bent.
The frames
7
a
and
7
b
are each structured such that a metal plate is bent substantially like U-letter, are shaped so as to constitute respective halves of a picture frame with portions corresponding to an observation surface cut away when the spread illuminating apparatus
1
′ is assembled, and cover the lamps
5
a
and
5
b
and a peripheral portion of the light conductive plate
2
. Thanks to the frames
7
a
and
7
b
, the components of the spread illuminating apparatus can be reliably fixed. And, since the light sources can be fixed in a predetermined position with respect to the respective light conductive bars, the lights emitted from the light sources can be efficiently guided in the light conductive bars.
However, the spread illuminating apparatus with the above-described frames has the following problems.
Since an area of the spread illuminating apparatus
1
′ with the frames
7
a
and
7
b
mounted thereon is substantially equal to an area of the LCD L, and also, since the spread illuminating apparatus
1
′ is superimposed over a top surface of the LCD L, the apparatus, as a whole, has a thickness equal to a total thickness of the LCD L, the lamp
5
a
or
5
b
(also the light reflection member
13
a
or
13
b
if attached), and the frame
7
a
or
7
b
. As a result, the total thickness is considerably increased.
Further, since lower frame portions of the frames
7
a
and
7
b
are inserted between the light conductive plate
2
and the LCD L, a wasted space is given for their thickness between the light conductive plate
2
and the LCD L.
FIGS. 6
to
8
are detailed schematic representations of the total thickness of the apparatus, and the space given between the light conductive plate
2
and the LCD L when the spread illuminating apparatus
1
′ is superimposed over the top surface of the LCD L.
FIG. 6
is an exploded perspective view of the entire apparatus substantially comprising the LCD L, the frame
7
disposed on the top surface of the LCD, and the light conductive plate
2
and the lamp
5
enclosed in the frame
7
.
FIG. 7
is a cross-sectional view through the line E—E in
FIG. 6
, and
FIG. 8
is a cross-sectional view through the line F—F in FIG.
6
.
The light conductive plate
2
and the lamp
5
are disposed so as to be enclosed in the frame
7
. In other words, the frame
7
covers the peripheral portion of the light conductive plate
2
, and the lamp
5
. Thus, the entire apparatus has a thickness equal to a total of the thickness P
3
of the LCD L and the thickness P
2
of the entire frame
7
. A lower portion of the frame
7
is disposed between the light conductive plate
2
and the LCD L, and a space equivalent to the thickness P
1
of the lower portion of the frame
7
is generated. Even when the P
1
is very slight, a screen of the LCD looks retracted as viewed from above the light conductive plate
2
, which gives a sense of discomfort to an observing person. In order to eliminate this trouble, the P
1
of the lower portion of the frame
7
may be reduced. However, this sacrifices the strength of the frame.
SUMMARY OF THE INVENTION
The present invention has been made in the light of the above problems. It is an object of the present invention to provide a spread illuminating apparatus which can reliably fi
Egawa Motoji
Takayanagi Kazutoshi
Minebea Co. Ltd.
Oliff & Berridg,e PLC
Tso Laura K.
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