Lighting panel for a display

Details Lighting panel for a display Lighting panel for a display

2003-03-03

2004-09-14

Dudek, James A. (Department: 2871)

Liquid crystal cells, elements and systems

Particular structure

Particular illumination

C362S035000

Reexamination Certificate

active

06791638

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a lighting panel for a display such as liquid crystal display (LCD) for illuminating the display from the underside thereof as a back light.
FIG. 10
is a plan view showing a conventional lighting panel, and
FIG. 11
is a sectional view taken along a line XI—XI of FIG.
10
.
The lighting panel
12
made of a transparent plastic has a rectangular shape in plan view and an incident surface
12
a
by beveling a corner. An edge light
11
of an LED is provided corresponding to the corner
12
a
. On the underside of the lighting panel
12
, a plurality of prisms
12
b
are formed as reflector members. The prisms
12
b
are concentrically formed with the light discharge point of the edge light
11
as shown in FIG.
11
. The prism
12
b
has a vertical angle of 90 degrees.
The light emitted from the edge light
11
enters the lighting panel
12
. The light in the lighting panel
12
is reflected by the prisms
12
b
and discharged from a discharge surface
12
c
. The discharged light enters a diffusion sheet
13
and discharges from the diffusion sheet to be applied to an LCD (not shown) in diffused rays.
Light discharged from the underside of the lighting panel
12
is reflected by a reflector sheet
14
to be returned to the lighting panel
12
.
In such a device, the intensity of light becomes reduced toward the end distant from the edge light
11
. Therefore, the LCD is not uniformly illuminated.
Furthermore, since the intensity of light in an area near the edge light is very high, prisms
12
b
must be arranged at high density, which causes the manufacturing cost to be increased and quality of the lighting panel
12
to reduce.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a lighting panel which may be easily manufactured with simple arrangement of prisms.
According to the present invention, there is provided a panel for lighting a display comprising a lighting panel made of a transparent plastic and having rectangular both surfaces one of which is a reflection surface and the other is a discharge surface, an incident surface formed by beveling one of corners of the lighting panel, an edge light provided corresponding to the incident surface, a plurality of prisms circularly formed on the reflection surface of the lighting panel, edge lines of the prisms being concentrically arranged with the edge light at a predetermined interval, each of the prisms having a vertical angle &thgr; comprising a first inclination angle &thgr;
1
(&thgr;
1
.
1
~&thgr;
1
.n) on the edge light side and a second inclination angle &thgr;
2
opposite to the first inclination angle &thgr;
1
, wherein the first inclination angle &thgr;
1
is set to 89.5°~60°, and there is a following relationship between the first inclination angle &thgr;
1
and the second inclination angle &thgr;
2
:
&thgr;
1
(&thgr;
1
.
1
~&thgr;
1
.
n
)>&thgr;
2
&thgr;
1
.
1
≦&thgr;
1
.
2
≦ . . . &thgr;
1
.(
m
−
1
)≦&thgr;
1
.
m
. . . &thgr;
1
.(
n
−
1
)≦&thgr;
1
.
n
The panel further comprises a prism sheet disposed corresponding to the discharge surface of the lighting panel, the prism sheet having a plurality of prisms on a surface corresponding to the discharge surface.
The prism has a circular edge line.
In another aspect, the prism is a circular lenticular lens.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.


REFERENCES:
patent: 6582095 (2003-06-01), Toyoda
patent: 6603520 (2003-08-01), Umemoto et al.
patent: 6731355 (2004-05-01), Miyashita

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