Illumination – Revolving
Reexamination Certificate
2002-01-11
2003-11-04
O'Shea, Sandra (Department: 2875)
Illumination
Revolving
C362S026000, C362S027000, C362S551000, C362S560000, C362S331000, C362S330000, C362S555000
Reexamination Certificate
active
06641275
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 signboards, various kinds of reflection-type display devices and the like, and more particularly to a spread illuminating apparatus used as an illuminating means for a liquid crystal display device.
2. Description of the Related Art
A demand for a liquid crystal display device as a display device mainly for computers has been increasing since the liquid crystal display device which operates with low power consumption is characterized by being low profile and lightweight. Since a liquid crystal which is a component of the liquid crystal display device does not emit light by itself unlike a light emitting element such as a cathode-ray tube, an illuminating means for viewing an image is required. In particular, in the recent demand for lower profile, there is a growing tendency to employ a thin plate-like spread illuminating apparatus of side light type (light conductive plate type) as an illuminating means for the liquid crystal display device.
An example of such a side light type spread illuminating apparatus is shown in
FIGS. 7
to
12
.
In
FIGS. 7 and 8
, this spread illuminating apparatus
1
is generally constituted such that a bar-like light source
3
is disposed close to one end surface
2
a
of a transparent substrate (a guide plate)
2
made of a light-transmissible material. A liquid crystal display device (not shown) is disposed on a lower surface side of the transparent substrate
2
, and this spread illuminating apparatus
1
is used as an auxiliary illumination for the liquid crystal display device.
The transparent substrate
2
is formed in a so-called wedge-shape, in which as the distance from the end surface
2
a
increases, the thickness of the transparent substrate
2
gradually degreases.
The light source
3
is generally composed of a light conductive member (a guide rod)
4
made of a bar-like transparent material disposed close to and along the end surface
2
a
of the transparent substrate
2
, an LED
6
(a spot-like light source) which is disposed facing one end part
4
a
of the light conductive member
4
and mounted on an FPC
5
(a printed circuit board) made of an insulating material, and a light reflection plate
7
disposed facing the other end part
4
b
of the light conductive member
4
.
An optical path conversion means
8
is provided on an opposite side surface
4
d
(a second surface of the light conductive member) of a surface
4
c
(a first surface of the light conductive member) facing the transparent substrate
2
on the light conductive member
4
. The optical path conversion means
8
is composed of grooves
8
a
each of which is substantially triangular in section, and flat portions
8
b
each of which is formed between two adjacent grooves
8
a.
Accordingly, the light rays from one end part
4
a
of the light conductive member
4
are uniformly radiated on the first surface
4
c
although the LED
6
is disposed on one end part
4
a.
A light reflection pattern
9
composed of grooves
9
a
and flat portions
9
b
is formed on one surface (an upper part in
FIG. 7
, hereinafter, referred to as “upper surface”) of the transparent substrate
2
so that the brightness is substantially uniform at any position of the transparent substrate
2
irrespective of the distance from the light conductive member
4
.
The LED
6
is substantially rectangular, and a groove-shaped recess
20
extending in the vertical direction is formed in a substantially center part of the surface facing an abutting surface on the light conductive member
4
.
The LED
6
has solder S applied to both ends
6
a
and
6
b
positioned to be aligned in a direction orthogonal to a longitudinal direction of the light conductive member
4
while disposed facing one end part
4
a
of the light conductive member
4
as shown in
FIGS. 7
,
10
and
11
, and a terminal (not shown) is electrically connected to a copper foil (not shown) provided on the FPC
5
, and mounted on the FPC
5
in this condition.
The FPC
5
is composed of a substantially rectangular FPC body
5
a
with the LED
6
or the like mounted thereon, and an FPC riser wall
5
b
formed on one end part of the FPC body
5
a
in a rising manner. The FPC rising wall
5
b
faces the LED
6
, and is interposed between the LED
6
and a frame riser plate
10
b
as described below, so that the solder S is prevented to be short-circuited to a metal lower frame
10
(the frame riser plate
10
b
).
As shown in
FIGS. 7
,
9
,
10
and
11
, this spread illuminating apparatus is further provided with the metal frame (the lower frame
10
) disposed on the lower surface side of the FPC
5
, and a substantially plate-like frame (an upper frame
11
) disposed facing the FPC
5
across the light conductive member
4
, and holds the transparent substrate
2
and the light source
3
. The lower frame
10
is substantially composed of a plate-like main body (a lower main body
10
a
) facing the lower face of the FPC
5
and extending along the light conductive member
4
, and a riser plate (the frame riser plate
10
b
) substantially orthogonal to the lower main body
10
a
and rising from one end part (the right side in
FIG. 10
) of the lower main body
10
a.
The other end part (the left side in
FIG. 10
) of the lower main body
10
a
and the transparent substrate
2
are fixed to each other (in a condition where a holding part not shown in the figure is provided), allowing the LED
6
to be pressed toward the light conductive member
4
by the frame riser plate part
10
b
as described below.
The lower frame
10
allows the frame riser plate part
10
b
facing one end face
4
a
of the light conductive member
4
via the FPC riser wall part
5
b,
and presses the LED
6
toward the light conductive member
4
via the FPC riser wall part
5
b.
Since the lower frame presses the LED
6
toward the light conductive member
4
, a coupling efficiency between the light conductive member
4
and the LED
6
is improved, and a variance in tolerance of members is absorbed thereby.
The spread illuminating apparatus is requested to tightly attach the light conductive member and the LED to each other in a reliable condition to obtain excellent light characteristics, and accordingly to improve the coupling efficiency between the light conductive member and the LED. However, in the conventional technology, the LED
6
is pressed toward the light conductive member
4
via the FPC
5
(the FPC riser wall
5
b
), and thus, no large pressure is obtained, and accordingly, the improvement in the coupling efficiency has been restricted.
In addition, in the conventional technology, the LED
6
is easily shifted in the direction T (the vertical direction in
FIG. 11
, and conveniently, referred to as the “longitudinal direction”) orthogonal to the longitudinal direction of the light conductive member
4
, and the coupling efficiency is easily degraded, accordingly.
SUMMARY OF THE INVENTION
The present invention has been made in the light of the above problems, and an object of the present invention is therefore to provide a spread illuminating apparatus to improve the coupling efficiency between the light conductive member and the spot-like light source.
According to a first aspect of the present invention, there is provided a spread illuminating apparatus comprising a transparent substrate made of a light-transmissible material; a bar-like light source composed of a light conductive member made of a transparent material and formed bar-like and a spot-like light source disposed on at least one end of the light conductive member and mounted on a printed circuit board, and disposed close to and along at least one end of the transparent substrate; a frame having a plate-like main body disposed either under the printed circuit board or above the bar-like light source so as to oppose the printed circuit board, extending along the bar-like light source, and adapted to hold the transparent substra
Ishii Takashi
Toyoda Koichi
Minebea Co. Ltd.
O'Shea Sandra
Tsidulko M.
LandOfFree
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