Liquid crystal cells – elements and systems – Particular structure – Interconnection of plural cells in series
Reexamination Certificate
2000-10-27
2003-01-28
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Interconnection of plural cells in series
C349S076000, C349S077000, C349S081000
Reexamination Certificate
active
06512559
ABSTRACT:
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 display device employing a Guest Host (GH) type display mode using a reflecting polarizer.
BACKGROUND OF THE INVENTION
Conventionally known is a reflection-type liquid crystal display device capable of modulating incident light between scattering (bright state) and absorption (dark state) by an application of a voltage, by dispersing a polymer having an anisotropic scattering function in a liquid crystal element employing a GH-type display mode in which a dichroic dye (Guest) having anisotropy in absorption of visible light in respective directions of a long axis and a short axis of a molecule is mixed with a liquid crystal (Host) having a certain molecular arrangement. The following will explain the conventional reflection-type liquid crystal display device as above based on FIG.
9
.
A reflection-type liquid crystal display (LCD) device
101
shown in
FIG. 9
is made up of a first substrate
102
, a second substrate
103
and a liquid crystal layer
104
which is a complex layer composed of the dichroic dye, liquid crystal and polymer, sandwiched between the first substrate
102
and second substrate
103
.
The first substrate
102
includes an insulating plate
105
a
which is a substrate, an absorbing later
106
, a reflecting polarizer
107
, a transparent electrode
108
a
and an orientation membrane
109
a
, which are provided in this order from the side of the insulating plate
105
a
and between the insulating plate
105
a
and the liquid crystal layer
104
. Note that, in
FIG. 9
,
110
is a seal material.
The second substrate
103
includes an insulating plate
105
b
as a substrate, a transparent electrode
108
b
, an orientation membrane
109
b
, which are provided in this order from the side of the insulating plate
105
b
and between the insulating plate
105
b
and the liquid crystal layer
104
.
The liquid crystal layer
104
which is placed between the first substrate
102
and second substrate
103
is made up of a liquid crystal molecule
104
a
of a nematic liquid crystal having a positive dielectric anisotropy, a so-called p-type dichroic dye
104
b
having a transitional dipole moment which is substantially parallel to the long axis of the molecule, and a polymer of polymerized molecules (polymer)
104
c
having an anisotropic molecular skeleton.
The insulating plate
105
a
of the first substrate
102
, and the insulating plate
105
b
of the second substrate
103
are composed of an insulating material, for example, such as glass, quartz and plastic. Further, at least the insulating plate
105
b
of the second substrate
103
is formed of a material having light transmissivity.
On a surface of the insulating plate
105
a
of the first substrate
102
on the side of the liquid crystal layer
104
are formed the absorbing layer
106
in contact with the insulating plate
105
a
as explained, and the reflecting polarizer
107
which is made up of, for example, a dielectric multilayer membrane having birefringence. Here, when forming the reflecting polarizer
107
, a transmitted axis of the liquid crystal layer
104
and that of the reflecting polarizer
107
are lined up with each other.
Further, in the first substrate
102
, the orientation membrane
109
a
which is provided on a surface of the reflecting polarizer
107
via the transparent electrode
108
a
in between, and the orientation membrane
109
b
which is provided under a surface of the insulating plate
105
b
via the transparent electrode
108
b
in between are made of, for example, polyimide resin. Furthermore, on respective surfaces of these orientation membranes
109
a
and
109
b
, on the sides which are in contact with the liquid crystal layer
104
, an orientation treatment, for example, by rubbing is performed so as to orient the liquid crystal molecule
104
a
of the nematic liquid crystal horizontally in one direction with respect to the first substrate
102
and second substrate
103
.
Next, the following will explain an operation when performing black and white display by using the reflection-type LCD device
101
with reference to FIGS.
10
(
a
) and
10
(
b
). FIG.
10
(
a
) shows a state of the reflection-type LCD device
101
when applying no voltage while FIG.
10
(
b
) shows a state of the reflection-type LCD device
101
when applying a voltage. Note that, light
111
which is emitted from surroundings (surrounding light) is indicated by linearly polarized light
111
a
having one polarization direction (oscillation direction) and linearly polarized light
111
b
having another oscillation direction which orthogonally intersects the former oscillation direction.
As shown in FIG.
10
(
a
), when applying no voltage, the liquid crystal molecule
104
a
of the liquid crystal layer
104
is oriented along an orientation direction of the orientation membranes
109
a
and
109
b
, that is, in a direction parallel to the first substrate
102
and second substrate
103
. In addition, the p-type dichroic dye
104
b
of the liquid crystal layer
104
is oriented in the same manner as the liquid crystal molecule
104
a.
When the light
111
which is incident from the side of the second substrate
103
is incident on the liquid crystal layer
104
, a component of the light
111
, i.e. the linearly polarized light
111
a
having its oscillation direction in a direction parallel to the long axis direction of the molecule of the p-type dichroic dye
104
b
is absorbed by the p-type dichroic dye
104
b
. Some of the linearly polarized light
111
a
cannot be absorbed by the p-type dichroic dye
104
b
and is transmitted. However, since the linearly polarized light
111
a
thus being transmitted through the liquid crystal layer
104
was scattered by the polymer
104
c
and became scattering light, it is reflected at the reflecting polarizer
107
and absorbed by the p-type dichroic dye
104
b
when passing through the liquid crystal layer
104
again.
Further, the linearly polarized light
111
b
having an oscillation plane in a vertical direction with respect to the long axis direction of the molecule of the p-type dichroic dye
104
b
passes through the liquid crystal layer
104
and reflecting polarizer
107
, and is absorbed by the absorbing layer
106
behind the reflecting polarizer
107
.
Thus, most of the linearly polarized light
111
a
do not emerge but absorbed by the liquid crystal layer
104
and absorbing layer
106
. Accordingly, when applying no voltage, most of the light which is incident on the reflection-type LCD device
101
is absorbed by the reflection-type LCD device
101
, thereby resulting in a dark state.
On the other hand, as shown in FIG.
10
(
b
), when applying the voltage, the nematic liquid crystal molecule
104
a
and p-type dichroic dye
104
b
of the liquid crystal layer
104
rise along a direction of the voltage, and are oriented in the vertical direction with respect to the first substrate
102
and second substrate
103
. However, the polymers
104
c
are chemically bound to one another so that a direction thereof cannot be changed. As a result, there arises a difference in refractive index between an area composed of the liquid crystal molecule
104
a
and p-type dichroic dye
104
b
, the molecules of which rose along the direction of the voltage, and an area composed of the polymers
104
c
, molecules of which did not rise. For this reason, the light incident on the liquid crystal layer
104
takes the scattering state.
Namely, when the light
111
incident from the side of the second substrate
103
is incident on the liquid crystal layer
104
, a component of the light
111
, i.e. the linearly polarized light
111
b
having its oscillation direction in the vertical direction with respect to the long axis direction of the molecule of the p-type dichroic dye
104
b
passes through the liquid crystal layer
104
and reflecting polarizer
107
, and is absorbed by the absorbing layer
106
beh
Hashimoto Kengo
Mitsui Seiichi
Ueki Shun
Birch & Stewart Kolasch & Birch, LLP
Dudek James
Rude Timothy
Sharp Kabushiki Kaisha
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