Illumination – Illuminated scale or dial – Edge illuminated modifier or light rod/pipe
Reexamination Certificate
2002-02-12
2004-06-22
O'Shea, Sandra (Department: 2875)
Illumination
Illuminated scale or dial
Edge illuminated modifier or light rod/pipe
C362S035000, C362S026000, C362S558000, C362S560000, C362S561000, C362S327000, C362S551000, C362S559000
Reexamination Certificate
active
06752504
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an illumination device and a reflection type liquid crystal device using the same, and more particularly to an illumination device capable of improving an optical efficiency of a light emitted from a light source and a reflection type liquid crystal device using the same.
2. Description of the Related Art
Generally, a voltage is applied to a liquid crystal display device to cause a change in an alignment of liquid crystal. As a result, the liquid crystal cells undergoes a change of optical characteristics such as a birefringence, a rotatory polarization, a dichroism and a light scattering according to the changed alignment of the liquid crystal. Therefore, the liquid crystal display device can display an image according to the changes of the optical characteristics of the liquid crystal cell.
The liquid crystal display is classified into a transmission type liquid crystal display using a backlight and a reflection type liquid crystal display using an external light source, depending on a light source. The transmission type liquid crystal display is widely used, but the use of the backlight increases the power consumption as well as the volume and weight of the liquid crystal display. In order to solve the above drawbacks of the transmission type liquid crystal display having the backlight therein, a reflection type liquid crystal display, which does not use the backlight, has been variously studied and developed.
In addition, the reflection type liquid crystal display is anticipated to replace the transmission type liquid crystal display due to consumer demands on portable information display devices. Computer terminals using such a reflection type liquid crystal display to which a white-and-black TN mode or a white-and-black STN mode is applied, are commercially available and research and development for a color reflection type liquid crystal display is currently underway.
The development of the color reflection type liquid crystal display is one of the important subjects targeted in IMT-2000 (International Mobile Telecommunications-2000), which is actively studied and developed as a next generation mobile telecommunication. In this regard, extensive research for lighter, slimmer and compact-sized structures is currently underway.
FIG. 1
is a schematic plan view showing an illumination device used in a conventional reflection type liquid crystal display.
Referring to
FIG. 1
, the illumination device
30
used in the conventional reflection type liquid crystal display includes a light source section
10
and a light guiding section
20
, which is provided at a side of the light source section
20
and guides the light from the light source section
10
to a liquid crystal display panel (not shown).
The light source section
10
includes a plurality of light sources
11
a
and
11
b
for emitting the light and a first light guiding plate
12
, which is provided at a side of the light sources
11
a
and
11
b
for guiding the light towards the light guiding section
20
. The light sources
11
a
and
11
b
include a light emitting diode (LED) in the form of a point-shaped light source. The light sources
11
a
and
11
b
are respectively installed at both ends
12
a
and
12
b
of the first light guiding plate
12
, so that the light emitted from the light sources
11
a
and
11
b
are incident into both ends
12
a
and
12
b
of the first light guiding plate
12
.
The first light guiding plate
12
has a hexahedron bar structure. The light guiding section
20
is arranged at a first side
12
c
of the first guiding plate
12
and patterns
12
e
are formed at a second side
12
d
of the first guiding plate
12
opposite the first side
12
c
. The light, which is incident into both ends
12
a
and
12
b
of the first guiding plate
12
, is reflected by the patterns
12
e
formed at the second side
12
d
of the first guiding plate
12
and incident into the light guiding section
20
through the first side
12
c
of the first guiding plate
12
.
The light guiding section
20
has a hexahedron plate structure. The light guiding section
20
is arranged above the liquid crystal display panel and guides the light incident from the light source section
10
towards the liquid crystal display panel.
However, in order to make a large screen for the reflection type liquid crystal display, it is required to increase the amount of the light emitted from the light source section
10
to obtain a desired brightness. In order to increase the amount of the light emitted from the light source section
10
, it is necessary to increase the number of light sources
11
a
and
11
b
installed at both ends
12
a
and
12
b
of the first light guiding plate
12
, so the width of the first light guiding plate
12
is also increased.
FIG. 2
is a plan view showing the conventional light source section with increased number of light sources.
Referring to
FIG. 2
, the light source section
10
includes a plurality of light sources
13
a
to
13
h
which are arranged at both ends
12
a
and
12
b
of the first light guiding plate
12
. In
FIG. 2
, four light sources are arranged at each end of the first light guiding plate
12
. The widths of both ends
12
a
and
12
b
of the first light guiding plate
12
are enlarged corresponding to the increased number of the light sources
13
a
to
13
h.
Therefore, since the number of the light sources
13
a
to
13
h
arranged at both ends
12
a
and
12
b
of the first light guiding plate
12
is increased by four times as compared with the number of the light sources
11
a
and
11
b
shown in
FIG. 1
, the brightness thereof has to be correspondingly improved.
However, as shown in
FIG. 2
, when the light sources
13
a
to
13
h
are arranged at both ends
12
a
and
12
b
of the first light guiding plate
12
, the light sources
13
a
and
13
e
are relatively adjacent to the patterns
12
e
, but the light sources
13
d
and
13
h
are relatively remote from the patterns
12
e
. The light generated from the light sources
13
d
and
13
h
remote from the patterns
12
e
of the first light guiding plate
12
rarely arrives at the patterns
12
e
of the first light guiding plate
12
as compared with the light generated from the light sources
13
a
and
13
e
adjacent to the patterns
12
e.
Accordingly, even though the number of light sources
13
a
to
13
h
arranged at both ends
12
a
and
12
b
of the first light guiding plate
12
increases, the brightness of the reflection type liquid crystal display cannot be sufficiently improved in proportion to the number of light sources.
SUMMARY OF THE INVENTION
The present invention solves the aforementioned problems, and provides an illumination device capable of improving an optical efficiency of a light emitted from a light source section.
Further, the present invention provides a liquid crystal display device having an illumination device capable of improving an optical efficiency of a light emitted from a light source section.
In one aspect of the invention, there is provided an illumination device including a light generator means for generating a light, a first light guiding plate including a first portion through which the light is incident and a second portion from which the light is emitted, and a second light guiding plate including opposite first and second side portions, at least one of which is adjacent to the light generator, a light projecting portion adjacent to the first portion of the first light guiding plate and a light reflecting portion having a distance from the light projecting portion. At least one light source is disposed adjacent to at least one of first and second side portions of the second light guiding plate for providing the light into the second light guiding plate. The distance between the light projecting portion of the second light guiding plate and the light reflecting portion becomes narrow as a number of light flex of the light emitted from the light generator decreases.
According
Kim Jin-Baek
Lee Keun-Woo
Cantor & Colburn LLP
O'Shea Sandra
Payne Sharon
Samsung Electronics Co,. Ltd.
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