Illumination – Revolving
Reexamination Certificate
2001-12-21
2003-10-07
Quach-Lee, Y. My (Department: 2875)
Illumination
Revolving
C362S027000
Reexamination Certificate
active
06629765
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spread illuminating apparatus, and more particularly to a spread illuminating apparatus used as an illuminating means for a liquid crystal display.
2. Description of the Related Art
A liquid crystal display which is low in profile, small in occupied volume and lightweight has been extensively used in electric products including portable telephones and personal computers, and its demand has been increased. However, since a liquid crystal which is a component of the liquid crystal display does not emit light by itself, it is necessary to provide a separate illuminating apparatus besides the liquid crystal display when used in dark places where the solar light or the illumination in a room is not fully available. Thus, this illuminating apparatus which irradiates liquid crystals is desired to be compact and small in power consumption. And, in recent years, a low profile spread illuminating apparatus of side light system (light conductive plate system) is often used as the illuminating means.
FIGS. 5
to
9
show an embodiment of such a spread illuminating apparatus of side light system.
FIG. 5
is a perspective view showing the spread illuminating apparatus. As shown in the figure, a spread illuminating apparatus
1
′ generally comprises a transparent substrate (a guide plate)
2
made of a light-transmissible material, and a bar-like light source
5
disposed close to an end surface
8
of the transparent substrate
2
. A liquid crystal display (not shown) is disposed under the transparent substrate
2
, and this spread illuminating apparatus
1
′ is used to auxiliarily illuminate the liquid crystal display.
The light source
5
comprises a bar-like light conductive member (guide rod)
3
made of a transparent material and disposed along and close to the end surface
8
of the transparent substrate
2
, and spot-like light sources (for example, LED)
4
a
and
4
b
disposed facing respectively ends
10
and
11
of the light conductive member
3
. The spot-like light sources
4
a
and
4
b
are mounted and soldered on a flexible printed circuit board (FPC)
6
′ formed of an insulating material.
Since an optical path conversion means
12
(comprising grooves substantially triangular in section and flat portions formed therebetween) is provided on a surface of the light conductive member
3
opposing a surface
9
facing the transparent substrate
2
, light emitted from the spot-like light sources
4
a
and
4
b
is adapted to enter the end surface
8
of the transparent substrate
2
in a substantially uniform manner.
The transparent substrate
2
is formed in a so-called wedge-shape in section in such a manner that the thickness thereof gradually decreases with the increase in distance from the end surface
8
. A light reflection pattern
19
comprising grooves
17
and flat portions
18
is formed on an upper surface
15
of the transparent substrate
2
, and in this configuration, light coming from the light source
5
and guided into the transparent substrate
2
is reflected in such a manner that an illumination is substantially uniform at the transparent substrate
2
irrespective of the distance from the light conductive member
3
.
For allowing light emitted from the spot-like light sources
4
a
and
4
b
to efficiently enter the transparent substrate
2
, a light reflection member (reflector)
13
is provided around the light conductive member
3
. The light reflection member
13
is formed to be substantially square U-shaped, and mounted to longitudinally cover the surfaces of the light conductive member
3
except for the surface
9
facing the transparent substrate
2
. The light reflection member
13
is formed of a hard resin having a film vapor-deposited with a metal such as silver, or a white film adhered on its inner surface, or a bent metal sheet of aluminum, stainless steel or the like.
FIGS. 6 and 7
illustrate the light source
5
showing a surface of the light conductive member
3
, on which the optical path conversion means
12
is formed.
FIG. 6
shows a view before the light conductive member
3
is fitted between the spot-like light sources
4
a
and
4
b,
and
FIG. 7
shows a view after the light conductive member
3
is fitted therebetween
FIG. 8
shows a top plan view of the light conductive member shown in FIG.
7
.
The spot-like light sources
4
a
and
4
b
are disposed facing the ends
10
and
11
, respectively, of the light conductive member
3
, and ends
21
a
and
21
a′,
and
21
b
and
21
b′
of the respective spot-like light sources
4
a
and
4
b
are soldered (hereinafter, a part which is soldered is referred to as “soldering part S”) on the FPC
6
′, whereby the spot-like light sources are electrically connected to a signal pattern (not shown) formed on the FPC
6
′.
The FPC
6
′ is substantially rectangular, and disposed under the spot-like light sources
4
a
and
4
b
and the light conductive member
3
disposed between the spot-like light sources
4
a
and
4
b.
The light conductive member
3
is disposed so that the ends
10
and
11
face the spot-like light sources
4
a
and
4
b,
respectively, namely, disposed so as to be sandwiched between the two spot-like light sources
4
a
and
4
b
mounted on the FPC
6
′. The surface
9
of the light conductive member
3
is positioned along the end surface
8
of the transparent substrate
2
with a predetermined distance from the end surface
8
.
To obtain excellent optical characteristics in the spread illuminating apparatus, it is required that the light conductive member and the LED's be tightly attached to each other while securely positioned, and that the coupling efficiency therebetween be satisfactory. However, in the conventional art, marginal spaces between the spot-like light sources
4
a
and
4
b
and the light conductive member
3
are necessary in order to smoothly fit the light conductive member
3
between the spot-like light sources
4
a
and
4
b
mounted on the FPC
6
′. The marginal spaces are necessary also for absorbing tolerances of members to be used (the light conductive member, the spot-like light sources, the FPC, etc.). Further, a positional error in mounting the spot-like light sources
4
a
and
4
b
on the FPC
6
′ should be also considered. Thus, as shown in
FIG. 9
(a blown-up view of Part P in FIG.
7
), a space
22
may exist between the light conductive member
3
and the spot-like light source
4
a
when the light conductive member
3
is placed between the spot-like light sources
4
a
and
4
b
, which degrades a coupling efficiency between both components.
SUMMARY OF THE INVENTION
The present invention has been made in light of the above problem. Accordingly, it is an object of the present invention to provide a spread illuminating apparatus to improve the coupling efficiency between a light conductive member and a spot-like light source.
In order to solve the above problem, according to a first aspect of the present invention, in a spread illuminating apparatus comprising a transparent substrate made of a light-transmissible material, a light source comprising a bar-like light conductive member and spot-like light sources provided at respective ends of the light conductive member, and disposed close to and along an end surface of the transparent substrate, and a flexible printed circuit board (FPC) disposed under the light conductive member, a portion to generate an elastic force in the longitudinal direction of the light source is formed in the FPC which has the spot-like sources mounted thereon and disposed at the respective ends of the light conductive member.
In the present invention, the light conductive member disposed between the spot-like light sources mounted on the FPC is surely fixed by the elastic force generated in the FPC and working in the longitudinal direction of the light source.
According to a second aspect of the present invention, in the spread illuminating appa
Ishii Takashi
Toyoda Koichi
Minebea Co. Ltd.
Oliff & Berridg,e PLC
Quach-Lee Y. My
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