Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-01-19
2001-12-11
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S149000, C349S150000, C349S113000
Reexamination Certificate
active
06330046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection type liquid crystal display device and, in particular, to a reflection type liquid crystal device superior in reliability and a method for manufacturing the same.
2. Description of the Related Art
Nowadays, a reflection type liquid crystal display device, which consumes relatively little power and which can be made small in thickness, is widely used as the display portion of a hand-held type computer or the like.
A known example of the reflection type liquid crystal display device is an outside type in which a reflection plate is arranged outside a pair of substrates provided on either side of a liquid crystal layer. However, in an outside type reflection type liquid crystal display device, the light entering the reflection type liquid crystal display device is reflected by a reflection film of the reflection plate after passing the two substrates, with the result that the bright display is rather dark.
To cope with this problem, there has been proposed a built-in type reflection type liquid crystal display device, in which there is arranged between a pair of substrates a reflection film whose surface is a mirror surface, and in which light is passed through only one substrate. However, in this reflection type liquid crystal display device, it is difficult to effectively utilize light, so that the contrast is rather low.
To eliminate this problem, there exists a built-in type reflection type liquid crystal display device as shown in
FIG. 13
, in which the metal reflection film for reflecting light has protrusions and recesses. In
FIG. 13
, numeral
1
a
indicates a first substrate, and
FIG. 1
b
indicates a second substrate. On the surface of the second substrate
1
b
opposed to the first substrate
1
a
, there are formed second electrode layers
9
b
and a second orientation film
4
b
, and on the surface on the opposite side, a phase plate
5
and a polarizing plate
6
are sequentially stacked one upon the other. On the other hand, on the surface of the first substrate
1
a
opposed to the second substrate
1
b
, an organic film
44
having a large number of protrusions and recesses, a metal reflection film
54
, an overcoat film
64
, a first electrode layer
94
a
, and a first orientation film
4
a
are sequentially stacked one upon the other. The overcoat layer
64
is provided in order to flatten out the protrusions and recesses of the metal reflection layer
54
, and to insulate the metal reflection film
54
from the electrode layer
94
a
. A liquid crystal layer
2
is sealed in the space surrounded the first substrate
1
a
and the second substrate
1
b
, having the above-mentioned layers, and a seal material held between them.
FIG. 14
is a plan view of the reflection type liquid crystal display device shown in
FIG. 13
, with the second substrate, the layers provided on the sides of the second substrate, the liquid crystal layer, the seal material, and the first orientation film being omitted. In
FIGS. 13 and 14
, numeral
7
indicates a driving element mounting region, and numeral
8
indicates a display region. Here, the driving element mounting region
7
is a region where a driving element is mounted, and the display region is a region used for the display of the liquid crystal display device.
As shown in
FIGS. 13 and 14
, on the overcoat film
64
of the driving element mounting region
7
, there is mounted a driving element
16
through the intermediation of an anisotropic conductive film
10
(hereinafter referred to as “ACF” having a conductive filler
10
a
. The ACF
10
has a conductive filler
10
a
, and conductivity can be imparted thereto by heating and pressurizing it.
The first electrode layer
94
a
of the driving element mounting region
7
connected to the display region
8
is electrically connected to one terminal
11
a
of the driving element
16
through the intermediation of the ACF
10
. Further, the other terminal
11
b
of t he driving element
16
is connected to the first electrode layer
94
c
through the intermediation of the ACF
10
.
In this reflection type liquid crystal display device, to stack the organic film
44
, the metal reflection film
54
, and the overcoat film
64
on the surface of the first substrate
1
a
, a photosensitive resin liquid is first applied, as shown in
FIG. 15
, to the first substrate
1
a
, which consists of a transparent glass plate or the like, and this photosensitive resin liquid is pre-baked to form a photosensitive resin layer
44
a
. Next, the pattern surface of a transfer pattern
14
having a flat portion
14
a
in the periphery is pressed against the photosensitive resin layer
44
a
on the first substrate la for a fixed period of time to transfer the protrusions of the transfer pattern
14
to the surface of the photosensitive resin layer
44
a
of the display region
8
shown in
FIG. 15
, and, as shown in
FIG. 16
, a large number of protrusions are formed. After this, rays
20
such as ultraviolet rays (g, h and i-rays) are applied to the whole from the back side (the lower side as seen in the drawing) of the first substrate to cure the photosensitive resin layer
44
b
having a large number of protrusions and recesses. After this, the transfer pattern
14
is detached from the photosensitive resin layer
44
b
, and post-baking is performed to obtain the organic film
44
as shown in FIG.
17
. Then, aluminum, silver or the like is vapor deposited on the display region
8
of the organic film
44
to form the metal reflection layer
54
as shown in FIG.
18
. After this, the overcoat film
64
shown in
FIG. 19
is formed by a thermosetting acrylic resin or the like.
As shown in
FIG. 13
, in this reflection type liquid crystal display device, the organic film
44
, the overcoat film
64
, the ACF
10
, and the first electrode layers
94
a
and
94
c
are provided between the driving element
16
and the first substrate
1
a
. Being formed of an organic substance, the organic film
44
is very soft. Thus, there is a fear that the terminals
11
a
and
11
b
of the driving element
16
will sink in to generate cracks in the first electrode layers
94
a
and
94
c
when the driving element
16
is electrically connected to the first electrode layers
94
a
and
94
c
by heating and pressurizing the ACF
10
. Further, due to the cracks, there is a fear that the first electrode layers
94
a
and
94
c
will suffer a break.
Further, it is difficult to bring the organic film
44
formed of a photosensitive resin into close contact with the first substrate
1
a
consisting of a glass plate. In particular, in the portion where it is exposed to the atmospheric air at the end surface of the reflection type liquid crystal display device, the organic film
44
takes up moisture, so that it is more liable to separation.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to solve the above problems and provide a highly reliable reflection type liquid crystal display device in which it is possible to prevent the generation of cracks in the first electrode layers as a result of sinking in of the terminals of the driving element to thereby reliably establish electrical connection between the driving element and the first electrode layers, and in which it is possible to prevent the organic film from being separated from the substrate.
Another object of the present invention is to provide a method for manufacturing such a reflection type liquid crystal display device.
To achieve the above object, there is provided, in accordance with the present invention, a reflection type liquid crystal display device comprising a pair of substrates, a seal material held between the pair of substrates, and a liquid crystal layer sealed in the space surrounded by the pair of substrates and the seal material, wherein, on the surface of one of the pair of substrates opposed to the other substrate, there are sequentially formed an organic film having a large number of protrusions and recesses, a
Ishitaka Yoshihiko
Moriike Tatsuya
Nakamura Sadao
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Chowdhury Tarifur R.
Sikes William L.
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