Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-08-28
2003-09-09
Chondhury, T. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S113000
Reexamination Certificate
active
06618107
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a manufacturing method of a reflection-type color liquid crystal display device and to the reflection-type color liquid crystal display device.
BACKGROUND OF THE INVENTION
In recent years, a practical application of a liquid crystal display device to information devices such as word processors, laptop personal computers and pocket televisions has been developing rapidly. Among liquid crystal display devices, a reflection-type liquid crystal display device which carries out display by reflection of externally incident light in particular, has been focused because it does not require a backlight, and thus it is capable of suppressing power consumption and reducing thickness and weight. In addition, it has been proposed to attain a reflection-type color liquid crystal display device using a color filter.
In a liquid crystal display panel which carries out display with the use of the color filter and reflected light (hereinafter referred to as reflection-type color LCD device), in case where a reflecting plate and the color filter are provided apart, problems arise as to mixed colors due to parallax, and considerable reduction in reflectance and chroma.
In order to solve the foregoing problems, there has been proposed a reflection-type color LCD device having an arrangement in which the color filter and the reflecting plate are provided within a liquid crystal cell. In addition, the reflection-type color LCD device, unlike a transmissive color LCD device, utilizes surrounding external light, and thus a high-transmissive color filter is required for the reflection-type color LCD device.
However, for example, if luminance is increased by covering an entire aperture with a pale color filter so as to attain high transmissivity, color balance deteriorates due to different transmissivity in each RGB.
Accordingly, a reflection-type color LCD device for preventing this adverse effect is proposed, for example, in Japanese Unexamined Patent Publication No. 197860/1998 (Tokukaihei 10-197860 published on Jul. 31, 1998).
The reflection-type color LCD device disclosed in the above publication (Tokukaihei 10-197860) has an arrangement as shown in
FIG. 6
in which a segment electrode
63
is provided between an upper substrate
61
and a liquid crystal layer
62
, while a common electrode
65
, a color filter
66
and a reflecting plate
67
are provided in this order from the side of the liquid crystal layer
62
between the liquid crystal layer
62
and a lower substrate
64
.
The segment electrode
63
and the common electrode
65
are shaped into stripes and are orthogonally disposed, and a portion where the segment electrode
63
and the common electrode
65
intersect makes up an aperture, where a coverage of the aperture by the color filter
66
ranges from 40% to 80%. Further, a color filter which is produced by a dyeing process without a black matrix is proposed to be the color filter
66
.
In the foregoing structure, since a black matrix is not used and the coverage of the aperture by the color filter
66
ranges from 40% to 80%, a high-luminance reflection-type color LCD device with excellent color balance can be provided.
However, in the structure where the color filter and the reflecting plate are provided within the liquid crystal cell, for example, the problem of detachment or deterioration of a metal oxide film, etc., which is a reflecting plate, arises when the reflecting plate or the color filter is adhered directly onto a glass substrate.
A technique for solving the foregoing problem is disclosed, for example, in Japanese Unexamined Patent Publication No. 14809/1999 (Tokukaihei 11-14809 published on Jan. 22, 1999).
A reflection-type LCD device disclosed in the above publication (Tokukaihei 11-14809) has an arrangement as shown in
FIG. 7
which includes a reflecting medium
74
composed of a metal reflecting film
71
and silicon oxide films
72
and
73
which are provided on both surfaces of the metal reflecting film
71
having uneven surfaces, and a color filter
75
formed on a surface of the reflecting medium
74
.
As such a color filter
75
, color filters produced, for example, by the following methods are proposed: a pigment dispersing method in which a pattern is formed by applying a pigment-dispersed color filter forming resist over the reflecting medium
74
, and a printing method in which a pattern which is formed on a print board is transferred onto the surface of the reflecting medium
74
through a blanket.
Further, the above publication (Tokukaihei 11-14809) also discloses that a black matrix is formed between color patterns of the color filter in order to improve contrast, etc. The black matrix includes those made of a metal thin film or resin including a black pigment.
As explained, since the silicon oxide film
72
is applied between the metal reflecting film
71
, which is a part of the reflecting medium
74
, and the color filter
75
, it is possible to prevent the metal oxide film, etc. as a reflecting plate from being detached.
Further, an electrodeposition method as another method of forming a color filter is disclosed in Japanese Unexamined Patent Publication No. 210901/1988 (Tokukaisho 63-210901 published on Sep. 1, 1988).
In this electrodeposition method, as shown in FIG.
8
(
a
), a transparent conductive layer
82
and a positive photosensitive resin composition layer
83
are formed on a substrate
81
. In addition, as shown in FIG.
8
(
b
), a positive mask
84
having a predetermined pattern is laid and exposed on the positive photosensitive resin composition layer
83
, which are eluted with a predetermined eluate. Next, as shown in FIG.
8
(
c
) , a current is flown to the transparent conductive layer
82
, and in an electrodeposition bath, for example, R (red) is electrodeposited on the transparent conductive layer
82
. Further, as shown in FIGS.
8
(
d
) through
8
(
g
), repeating the same process causes the photosensitive resin composition layer
83
to include colored portions. Next, as shown in FIGS.
8
(
h
) through
8
(
j
), light exposure and elution in the eluate are performed on the entire surface, which results in forming a transparent conductive layer
82
on which filters of R (red), G (green) and B (blue) are placed.
The electrodeposition method presents such an advantage that manufacturing processes are simplified so as to allow manufacture of a color filter at lower costs than those by the conventional pigment dispersing method and the printing method.
Further, as another conventional example, a technique for enhancing reflectance of a reflecting film used for a reflection-type LCD device is, for example, disclosed in Japanese Unexamined Patent Publication No. 2707/1999 (Tokukaihei 11-2707 published on Jan. 6, 1999).
In the above publication (Tokukaihei 11-2707), it is disclosed that a first transparent film which is made of, for example, an ITO film is stacked on silver or silver alloy, and a second transparent film which is made of a silicon oxide film is further stacked thereon, which results in forming a so-called enhanced reflection film in which reflectance is enhanced. In addition, a condition of thickness of the first and second transparent films is given by
(2
m
+1)&lgr;/4
n
(m: an integer of not less than 0,
&lgr;: a wavelength of incident light).
Consequently, reflectance is enhanced with the use of silver or silver alloy instead of aluminum, and by considering the condition of film thickness.
Meanwhile, currently, the reflection-type color LCD device having a color filter within a liquid crystal cell requires that a black matrix, which is a light shielding film, be provided between patterns of the color filter so as to improve contrast.
However, when the black matrix is to be formed between patterns of the color filter in the conventional reflection-type color LCD device, the following problems arise:
{circle around (1)} A metal black matrix, made of metal, has surface reflection and could block transmitted light in a transmissive LCD device. However,
Tanaka Mitsuhiro
Yoshimura Kazuya
Chondhury T.
Conlin David G.
Jensen Steven M.
Nguyen Hoan
LandOfFree
Reflection-type color liquid crystal display device and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reflection-type color liquid crystal display device and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reflection-type color liquid crystal display device and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3035348