Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-09-05
2002-12-03
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S154000, C349S188000
Reexamination Certificate
active
06490022
ABSTRACT:
TECHNICAL FIELD
This invention relates to a liquid crystal display device which uses a polymer dispersion type liquid crystal or polymer network liquid crystal as a liquid crystal layer, which does not require a polarizing film, and a method of fabricating the same.
BACKGROUND TECHNOLOGY
There has been an increasing development of various types of liquid crystal display devices (display panels) which are rendered thin and light with low power consumption. There has been recently a growing demand for a lighter and thinner display device a high demand for a low cost display device.
As a means for rendering the liquid crystal display device thin and light, it is conceived that a substrate to be used is made thin. Since a glass substrate is generally employed by a liquid crystal display device, it is a most efficient means to render the liquid crystal display device thin and light by rendering the glass substrate thin.
There has been an increasing development of reflection-type liquid crystal display devices to obtain an excellent display quality even in outdoors in fine weather. Since the reflection-type liquid crystal display device can effect a display utilizing an external light without using a backlight consuming much power, it has been fairly developed so as to realize a liquid crystal display device having less power consumption.
Reflection-type liquid crystal display devices are roughly divided into two types, a first type is a device utilizing a polarizing film and a second type is a device not using a polarizing film.
A main type of the second reflection-type liquid crystal display device not using the polarizing film comprises two types, namely, one type using a liquid crystal layer composed of a guest-host liquid crystal including a dye contained in a liquid crystal, and another type using a liquid crystal layer composed of a polymer dispersion type liquid crystal having liquid crystal dispersed in a polymer or a polymer network type liquid crystal having liquid crystal which is present in gaps between net-like polymers.
Since these two types of reflection-type liquid crystal display devices effect display while the liquid crystal layer per se is varied in a transparent state and an opaque state depending on the presence or absence of a voltage applied to the liquid crystal layer, a polarizing film is not needed, thereby effecting a bright display.
As far as low cost is concerned, an honest and steady endeavor such as the reduction of cost of a material, saving of a material to be used, or the like is carried out.
There is a liquid crystal material as a typical wasteful material to be used, and various proposals are made for saving the liquid crystal material. As an example, there is proposed a liquid crystal display device as disclosed in JP 58-37527, B.
The outline of this liquid crystal display device is explained with reference to FIG.
5
. The liquid crystal display device is fabricated integrally in a configuration where a plurality of liquid crystal display devices are arranged in a row as shown in FIG.
5
. Respective liquid crystal display devices
10
comprise two transparent glass substrates
1
,
2
(they seem only one glass substrate because they are overlapped with each other), and these glass substrates
1
,
2
are bonded to each other to form given gaps
4
by seals
3
provided on portions of respective liquid crystal display devices
10
.
Pouring ports
5
are provided on each side
3
a
(lower side in
FIG. 5
) common to the seals
3
at the center thereof for pouring liquid crystal material into the gaps
4
between two glass substrates
1
,
2
. Barriers
6
formed of the same sealing member are provided on both ends of the respective sides
3
a
so as to join the seals
3
of adjoining liquid crystal display devices
10
.
The barriers
6
serve to prevent the liquid crystal material from entering between the seals
3
of the adjoining liquid crystal display devices
10
when pouring the liquid crystal material into the gaps
4
of a plurality of liquid crystal display devices
10
which are integrally formed with one another.
Accordingly, since the liquid crystal material proceeds forward inside the gaps
4
surrounded by the seals
3
of the respective liquid crystal display devices
10
and the front surface of the respective sides
3
a
in which each pouring port
5
is provided, the liquid crystal material scarcely enters unwanted areas, thereby saving the liquid crystal material to the maximum.
Further, if only the configuration of the seals
3
is devised, the barriers
6
can be formed at the same time when the seals
3
are formed so that the liquid crystal material can be saved without adding an extra process when fabricating the liquid crystal display device, thereby greatly contributing to the low cost of the liquid crystal display device.
After pouring the liquid crystal material into the gaps
4
of the respective liquid crystal display devices
10
, the pouring ports
5
of the seals
3
are sealed by a sealing agent, not shown, thereby forming liquid crystal layers which are sealed between two glass substrates
1
,
2
of the respective liquid crystal display devices
10
.
Finally, two glass substrates
1
,
2
are cut along positions depicted by prescribed cut lines
18
, thereby separating the liquid crystal display devices
10
from each other so as to complete individual liquid crystal display devices
10
.
Since the reflection-type liquid crystal display device not using a polarizing film can effect a bright display, it has been fairly developed, and it mainly comprises a type using a guest-host liquid crystal as a liquid crystal layer and another type using a polymer dispersion type liquid crystal or a polymer network type liquid crystal as the liquid crystal layer.
For example, when a display device using a polymer dispersion type liquid crystal or a polymer network type liquid crystal is fabricated, as explained with reference to
FIG. 5
, a liquid crystal material formed of a mixture composed of a monomer and the liquid crystal material is poured into the gaps
4
formed by the seals
3
between two glass substrates
1
,
2
and the gaps are sealed, then the entire surface of the display device is irradiated with ultraviolet rays to polymerize the monomer in the liquid crystal material, thereby forming a liquid crystal layer formed of a polymer dispersion type liquid crystal or a polymer network type liquid crystal.
Meanwhile, typical liquid crystal display devices have terminal areas
14
having terminals provided on an internal surface of at least one of two glass substrates
1
,
2
outside the seals
3
for electrically connecting electrodes (not shown) formed on the confronted inner surfaces of two glass substrates
1
,
2
to an external circuit, as shown in FIG.
6
.
When the liquid crystal display devices
10
are separated from one another by cutting two glass substrates
1
,
2
, the two glass substrates
1
,
2
need to be separated at different positions so as to expose the terminal areas
14
.
That is, the first substrate
1
positioned at the upper side in
FIG. 6
is cut along first prescribed cut lines
7
, and the second substrate
2
positioned at the lower side in
FIG. 6
is cut along second prescribed cut lines
8
,
8
every two positions so that the second substrate
2
confronting the terminal areas
14
of the first substrate
1
is removed when the liquid crystal display devices
10
are separated from each other, thereby exposing the terminal areas
14
.
However, since the barriers
6
are formed of the same material as the seals
3
, the terminal areas
14
formed on an inner surface of the first substrate
1
and the inner surface of the second substrate
2
confronting the terminal areas
14
are bonded to each other by the barriers
6
formed of a sealing member, so that the barriers
6
need to be peeled off by a force exceeding a force for adhering or bonding the glass substrates
1
,
2
when the glass substrates
1
,
2
are cut.
Since the sealing member has a strong adhesive force inher
Citizen Watch Co. Ltd.
Dudek James
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