Liquid crystal cells – elements and systems – Particular structure – Particular illumination
Reexamination Certificate
1997-12-05
2001-11-06
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Particular illumination
C362S035000
Reexamination Certificate
active
06313891
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device for guiding light from a backlight source to a light transmission member and irradiating a liquid crystal panel, and more specifically, to the improvement of the brightness of the liquid crystal panel.
2. Description of the Related Art
As shown in
FIG. 11
, a conventional ordinary liquid crystal display device is arranged such that: successively laminated on the back surface of a liquid crystal panel
31
are a protection/diffusion sheet
32
; two lens sheets
33
disposed under the protection/diffusion sheet
32
for improving the brightness of light; a diffusion plate
34
disposed under the lens sheets
33
for diffusing the light; a light transmission member
35
composed of an acryl resin or the like and disposed below diffusion plate
34
, a light transmission member reflection pattern
35
b
formed on the bottom surface of the light transmission member
35
by silk print or when the light transmission member is molded for reflecting the light upward; and a reflection sheet
36
disposed under the light transmission member
35
for reflecting the light upward. Further, a backlight source
38
composed of a cold cathode fluorescent lamp (CCFL) or the like is disposed in a lamp holder
37
on the one end surface
35
a
of the light transmission member
35
and a U-shaped reflection film
39
is held in the lamp holder
37
on the upper, lower and back sides of the backlight source
38
to reflect the light from the backlight source
38
forward.
The above respective components are held by an upper holder
40
and a lower holder
41
as a frame member.
The light from the backlight source
38
and the light reflected at the reflection film
39
are irradiated to the one end surface
35
a
of the light transmission member
35
positioned forward of the backlight source
38
and the light from the end surface
35
a
is entered into the light transmission member
35
. Then, the incoming light can reach every point in the light transmission member
35
while irregularly reflecting therein.
The incoming light which irregularly reflects in the light transmission member
35
is reflected at the light transmission member reflection pattern
35
b
on the bottom surface of the light transmission member
35
, the reflection sheet
36
under the light transmission member
35
and so on in an approximately vertical direction and emerges from the upper surface of the light transmission member
35
.
At the time, the light from the backlight source
38
also emerges from the upper surface of the of the portion of the light transmission member
35
which is located on the other end surface (not shown) side thereof which is apart from the backlight source
38
.
The light emerged from the upper surface of the light transmission member
35
is caused to pass through the diffusion plate
34
, the lens sheets
33
, the protection/diffusion sheet
32
on the lens sheets
33
and so on so that it can irradiate the effective display area
31
a
of the liquid crystal panel
31
from the backside thereof.
In the liquid crystal display device described above, however, the light which irradiates the liquid crystal panel
31
includes two kinds of light beams. One of the light beams, that is, a first light beam is such that when the light which emerges from the backlight source
38
and the reflection film
39
and travels straight in an approximately horizontal direction enters the light transmission member
35
, the light irregularly reflects in the light transmission member
35
and the thus irregularly reflected light is reflected at the light transmission member reflection pattern
35
b
on the bottom surface of the light transmission member
35
, the reflection sheet
36
under the light transmission member
35
and so on while changing its direction approximately perpendicularly to the light transmission member
35
, then emerges upward from the upper surface of the light transmission member
35
and irradiates the entire surface of the effective display area
31
a
of the liquid crystal panel
31
from the backside thereof.
Whereas, the other of the light beams, that is, a second light beam is such that when an oblique light beam A shown by the arrow in
FIG. 11
emerges from the backlight source
38
and the reflection film
39
obliquely upward with respect to the end surface
35
a
of the light transmission member
35
and enters the light transmission member
35
, the oblique light beam A passes through the light transmission member
35
straight in an obliquely upward direction without irregularly reflecting in it, emerges from the light transmission member
35
and irradiates, in addition to the first light beam, the portion of the effective display area
31
a
which is shown in the schematic plan view of the liquid crystal display device in FIG.
12
and located near to the edge
31
b
thereof in the vicinity of the backlight source
38
, for example, the portion of the effective display area
31
a
within the range of 10 mm from the edge
31
b
of the liquid crystal panel
31
.
Since the portion of the effective display area
31
a within the range of 10 mm from the edge
31
b
of the liquid crystal panel
31
is irradiated by the composite light beam composed of both the first and second light beams, the above portion of the effective display area
31
a
is brighter than the other portion thereof and “glittering state” emission lines
31
c
are generated. Accordingly, there is a problem that the brightness of the effective display area
31
a
of the liquid crystal panel
31
is made uneven.
As a coutermeasure to cope with the above problem, the conventional liquid crystal display device has a black or gray colored portion
36
a
formed thereto by print or the like within the range of approximately 10 mm, which is near to the backlight source
38
, of the reflecting surface of the reflection sheet
36
under the light transmission member
35
to absorb a part of the first light beam so that the generation of the emission lines
1
c
is prevented by lowering the brightness of the effective display area
31
a
within the range of approximately 10 mm thereof near to the edge
31
b.
In the conventional liquid crystal display device, however, since the “glittering state” emission lines
31
c
which are generated to the effective display area
31
a
of the liquid crystal panel
31
are prevented by the provision of the black or gray colored portion
36
a
formed within the range of approximately 10 mm near to the backlight source
38
of the reflection sheet
36
, there is a problem that the surface brightness in the liquid crystal display area is lowered, although there is an effect that the light of the backlight source
38
is partly absorbed by the colored portion
36
a
and the quantity of light emerged upward from the light transmission member
35
is reduced and the generation of the emission lines is prevented.
As shown in
FIGS. 13 and 14
, another conventional liquid crystal display device has a reflector
59
whose interior is formed to a U-shape so as to encase a backlight source
38
.
A reflecting surface
59
b
to which glossy processing is applied is formed to the interior of the opening
59
a
of the reflector
59
so that the reflecting surface
59
b
reflects the light irradiated from the backlight source
38
forward and irradiates the end surface
55
a
of a light transmission member
55
.
Further, a case portion
59
c
on which the aforesaid respective components are placed is formed to the reflector
59
integrally therewith. The respective members are held by the reflector
59
having the case portion
59
c
and an upper holder
40
acting as a frame member.
According to the liquid crystal display device arranged as described above, in the liquid crystal panel
31
shown in
FIG. 12
which shows the schematic plan view of the liquid crystal display device, there is a second light beam, that is, a reflected light beam C
1
which irradiates, in addition t
Kakuta Ryohei
Matsubara Satoshi
Nagakubo Hideaki
Yamazaki Mitsuaki
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Parker Kenneth
LandOfFree
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