Polymer dispersed liquid crystal display device and method of producing a display device

Reflective pixels composed of chromium are formed on a substrate and a polyimide film is provided on the substrate. Rubbing in two directions is conducted through a mask rubbing process. Transparent pixel electrodes, composed of indium tin oxide (ITO), are formed on a substrate, a polyimide film is formed on another substrate, and orientation processing is conducted in the same direction over the entire surface. A polymer dispersion liquid crystal is provided between these two substrates. The liquid crystal does not contain a chiral agent. The liquid crystal is divided into a left twist area having a left twist orientation state and a right twist area having a right twist orientation state. Between the substrates, the polymer and the liquid crystal are mutually orientation dispersed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a liquid crystal display device and a 
method for producing a liquid crystal display device. More particularly, 
the present invention relates to a liquid crystal display device 
comprising the display component of an information equipment terminal, 
television or home appliance product, and a method of producing the liquid 
crystal display device. 
2. Description of Related Art 
In recent years, as information equipment has become more compact and 
lightweight, display devices to be mounted on such equipment have been 
sought that consume less power. Liquid crystal display devices, by means 
of the TN mode, are utilized as reflective displays in small display 
capacity equipment. Liquid crystal display devices, by means of the FTN 
mode, are utilized in mid-range display capacity equipment. Furthermore, 
uses wherein an information input apparatus, such as a tablet or the like, 
is included on the reflective-type display are also expanding, and 
brightness and good visibility are required in reflective-type liquid 
crystal display devices. 
However, because TN-format and FTN-format liquid crystal display devices 
that use conventional polarizing plates have low light utilizing 
efficiency, the problem arises that these displays become dark when made 
reflective. Moreover, an extremely dark display results when an 
information input apparatus, such as a tablet or the like, is included. In 
addition, because a reflective plate is placed over the polarizing plate 
on the back surface of the substrate, positioned on the back side of the 
device, in order to make a reflective model with TN format or FTN format, 
double images occur in the display, small characters are unclear, and 
there are problems with visibility. 
On the other hand, bright reflective-type displays that do not use 
polarizing plates have come to be developed recently. For example, a 
liquid crystal display device that uses a polymer dispersion liquid 
crystal in which liquid crystal and polymer are mutually dispersed, and 
that performs control so that the display is transparent when an electric 
field is applied and the light is scattered when no electric field is 
applied has been disclosed (Japanese Laid-Open Patent Publication Sho 
58-501631). Liquid crystal display devices that perform control so that 
the light is scattered when an electric field is applied and the display 
is transparent or light is absorbed when no electric field is applied have 
also been disclosed (European Patent Application EPO 488116A2, Japanese 
Laid-Open Patent Publication Hei 4-227684, Japanese Laid-Open Patent 
Publication Hei 5-119302). 
In particular, in the polymer dispersion-type liquid crystal display device 
using a polymer dispersion liquid crystal disclosed in European Patent 
Application EPO 488116A2, in which the liquid crystal and polymer are 
mutually orientation dispersed, it is possible to also use the electrodes 
as light reflecting surfaces because no polarizing plate is used. In this 
case, visibility, high precision and brightness, which cannot be achieved 
in TN and FTN modes that require polarizing plates, are obtained, and it 
is possible to obtain a reflective display with superior display quality. 
However, the conventional art that has been disclosed with regard to 
polymer dispersion type liquid crystal display devices use polymer 
dispersion liquid crystal in which the liquid crystal and polymer are 
mutually orientation dispersed. Although it is possible to resolve the 
problems of a liquid crystal display device that uses a polarizing plate, 
it is necessary for the liquid crystal to be twisted by not less than 
360.degree. in order to obtain sufficient scattering characteristics and 
to secure brightness. As a result, the problem arises that the driving 
voltage becomes high. 
For example, large capacity displays are possible by forming active devices 
such as TFT (thin film transistor) or MIM (metal-insulator-metal) devices 
at each pixel and providing electric signal control at each pixel. 
However, because the driving voltage of the polymer dispersion liquid 
crystal is high, it is difficult to drive the liquid crystal so that the 
liquid crystal responds adequately from the standpoint of the voltage 
resistance of active devices. The problems also arise that the contrast 
ratio tends to fall and driving drivers are necessary that can withstand 
high voltages. 
In addition, because of the orientation dispersion structure, the problem 
arises that there is directivity in the scattering. Directivity is when 
the light scattering efficiency changes based on the direction of the 
external incident light. For example, the brightness changes as the panel 
is rotated, and the problem then arises that the visibility is easily 
influenced by the usage environment. To the extent that the twisting of 
the liquid crystal is small, the directivity is larger. Accordingly, the 
twisting of the liquid crystal should be made larger in order to resolve 
this problem, but when this is done, the driving voltage becomes large. 
Consequently, making the twisting larger is impossible from the standpoint 
of the driving voltage. 
Furthermore, when large quantities of a chiral agent are added in order to 
create a large twisting force, the problem arises that hysteresis is 
created in the electro-optical properties. 
The present invention was made in order to solve these types of problems, 
and its purpose is to provide a liquid crystal display device, through 
controlling to a new orientation state a liquid crystal that is mutually 
orientation-dispersed with a polymer. The liquid crystal display device 
can be operated at low voltage, is bright, has a high contrast ratio, has 
improved scatter directivity, and has visibility that has only low 
dependence on the usage environment and which has superior portability. 
The present invention is also directed to the method of producing such a 
liquid crystal display device. 
SUMMARY OF THE INVENTION 
In order to resolve the above and other problems, the present invention 
provides: a liquid crystal display device, of the type comprised of a 
liquid crystal and an anisotropic polymer, the orientations of which are 
mutually dispersed, interposed between a first substrate in which pixel 
electrodes are formed and the surface is orientation processed, and a 
second substrate, in which electrodes facing these pixel electrodes are 
formed and the surface is orientation processed; wherein the pixels are 
divided into at least a right-twist orientation area and a left-twist 
orientation area, and the liquid crystal is right-twist oriented between 
the first substrate and the second substrate in the right-twist 
orientation area, and is left-twist oriented between the first substrate 
and the second substrate in the left-twist orientation area. 
Thus, the pixels are divided at least into a right-twist orientation area 
and a left-twist orientation area, with the liquid crystal having a 
right-twist orientation in the right-twist orientation area and a 
left-twist orientation in the left-twist orientation area. Consequently, 
the directivity of the scattering becomes small. Accordingly, it is not 
necessary to make the twisting of the liquid crystal larger in order to 
resolve the problem of directivity. As a result, driving is possible at 
low voltages. In addition, it is not necessary to add large quantities of 
the chiral agent in order to make the twisting of the liquid crystal 
larger. As a result, even if hysteresis is created in the electro-optical 
properties, this can be controlled. 
It is preferable for the size of the twisting angle of the liquid crystal 
in the right-twist orientation area and the size of the twisting angle of 
the liquid crystal in the left-twist orientation area to be substantially 
equivalent. In this way, the directivity of the scattering is made 
extremely small. 
It is preferable for the orientation direction of one of the first 
substrate and the second substrate in the right-twist orientation area and 
the orientation direction of one of the first substrate and the second 
substrate in the left-twist orientation area to be the same. It is also 
preferable for the orientation direction of the other of the first 
substrate and the second substrate in the right-twist orientation area and 
the orientation direction of the other of the first substrate and the 
second substrate in the left-twist orientation area to be opposite. 
It is preferable for the twisting angle of the liquid crystal to be 
45.degree. to 90.degree.. When the angle is smaller than 45.degree., the 
scattering directivity is strong and the visual properties are poor. In 
addition, when 90.degree. is exceeded, a reverse twist domain is created. 
It is preferable for a light-shielding layer to be formed on at least one 
of the first substrate and the second substrate of the boundary between 
the right-twist orientation area and the left-twist orientation area. In 
this way, the discrimination line of the orientation boundary is shielded 
from the light, and a uniform display is obtained. 
It is preferable for a light-shielding layer to be formed on at least one 
out of the first substrate and the second substrate between pixels. In 
this way, light leaks caused by the liquid crystal response above the 
arranged line are shielded. 
It is preferable for either the pixel electrodes of the first substrate or 
the electrodes of the second substrate to be formed of a reflective 
material. The present invention is preferably applied to a reflective-type 
liquid crystal display device. 
It is preferable for the liquid crystal to not contain a chiral agent. This 
is because the twisting direction matches either left or right when the 
chiral agent is included. 
In addition, with the present invention a method of producing a liquid 
crystal display device is provided, said method comprising: 
a procedure for forming pixel electrodes in the first substrate; 
a procedure for forming electrodes in the second substrate, that face the 
pixel electrodes; 
a procedure for orienting, in a first direction, one of the first substrate 
and the second substrate in a first area of the pixel electrodes; 
a procedure for orienting, in a second direction opposite the first 
direction, one of the first substrate and the second substrate in a second 
area different from the first area of the pixel electrodes; 
a procedure for orienting the other of the first substrate and the second 
substrate; 
then, a procedure for forming a vacuum panel using the first substrate and 
the second substrate; 
a procedure that places a liquid crystal mixture material composed of a 
polymer or polymer precursor and a liquid crystal compound between the 
first and second substrates of the vacuum panel; and 
then, a procedure for separating the polymer from the liquid crystal 
mixture material and mutually separating the liquid crystal and the 
polymer. 
In this way, by orienting in a first direction one of the first substrate 
and the second substrate in a first area of the pixel electrodes, 
orienting in a second direction opposite the first direction one of the 
first substrate and the second substrate in a second area that is 
different from the first area of the pixel electrodes, orienting the other 
of the first substrate and the second substrate, forming a vacuum panel 
using the first substrate and the second substrate, and placing a liquid 
crystal mixture material composed of a polymer or polymer precursor and a 
liquid crystal compound between the first and second substrates of the 
vacuum panel, a liquid crystal display device is made. The device has 
pixel electrodes that are partitioned into a first orientation area and a 
second orientation area, with the liquid crystal mixture material having a 
right-twist orientation between the first substrate and the second 
substrate in the first orientation area, and a left-twist orientation 
between the first substrate and the second substrate in the second 
orientation area. Furthermore, by then separating the polymer out from the 
liquid crystal mixture material and mutually separating the liquid crystal 
and the polymer, it is possible to keep the orientation state of the 
liquid crystal in the orientation state of the liquid crystal mixture 
material prior to mutual separation, with the liquid crystal having a 
right-twist orientation between the first substrate and the second 
substrate in the first orientation area and a left-twist orientation 
between the first substrate and the second substrate in the second 
orientation area.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
First Embodiment 
A cross-sectional view of the liquid crystal display device of the present 
invention is shown in FIG. 1A. In addition, a planar view, as seen from 
the top substrate 101, is shown in FIG. 1B. 
Chrome is formed to a thickness of about 2000 angstroms through sputtering 
on the bottom substrate 108 and is then patterned to form a reflective 
pixel electrode 107 with 15 mm.sup.2 of pixel surface area. Following 
this, Optomer AL 3046 (produced by Japan Synthetic Rubber Co. Ltd.) is 
flexographed as an orientation agent on substrate 108, and is then 
calcinated for one hour at 180.degree. C. to form a polyimide film 106. 
Next, the bi-directional rubbing process using the mask rubbing method will 
be described. First, a resist film is formed on the above-described 
substrate 108 and is then exposed using the mask 1 shown in FIG. 2A and is 
developed. Next, a rubbing process is conducted using a rotating rubbing 
apparatus, following which the resist film is peeled off, completing one 
cycle of the mask rubbing. The rubbing direction is indicated by reference 
number 109 in FIG. 1B. Following this, a resist film is again formed on 
the substrate 108 and is then exposed using the mask 2 shown in FIG. 2B 
and is developed. Next, a rubbing process is conducted using a rotating 
rubbing apparatus, following which the resist film is peeled off and the 
second cycle of the mask rubbing is completed. The rubbing direction is 
indicated by reference number 110 in FIG. 1B. 
ITO (indium tin oxide) is formed to a thickness of about 1500 angstroms 
through sputtering on the top substrate 101 and is then patterned to form 
a transparent pixel electrode 102. Optomer Al 3046 (produced by Japan 
Synthetic Rubber Co. Ltd.) is flexographed as an orientation agent on the 
substrate 101 and is then calcinated for one hour at 180.degree. C. to 
form a polyimide film 103. Next, the polyimide film 103 is oriented in the 
same direction over the entire surface by means of a rotating rubbing 
apparatus. The rubbing direction is indicated by reference number 111 in 
FIG. 1B. 
Next, a vacuum panel is made by bonding and anchoring the perimeters of the 
two substrates with a spacing of 5 .mu.m between the two substrates. 
The angle formed by the bottom substrate rubbing direction 109 and the top 
substrate rubbing direction 111 is set at 89.degree., and the angle formed 
by the bottom substrate rubbing direction 110 and the top substrate 
rubbing direction 111 is set at 89.degree.. 
Next, the liquid crystal and polymer precursor compound that is sealed in 
this vacuum panel will be described. A mixture of TL-213 (produced by 
Merck & Co. Inc.) and MJ92786 (produced by Merck & Co. Inc.) in a 7:3 
ratio was used as the liquid crystal (hereafter called liquid crystal A). 
In addition, M361, SI512 and M137 (all produced by Mitsui Toatsu Senryo 
K.K.) were mixed into this mixture in ratios of 1.4%, 1.7% and 0.4% by 
weight, respectively, as the bi-color pigments. A chiral agent was not 
added to the liquid crystal mixture. In addition, 7% by weight of biphenyl 
acrylate, with respect to the above liquid crystal compound, was used as 
the polymer precursor. The above was heated and mixed to achieve a liquid 
crystal state, and after this, was vacuum sealed in the above-described 
vacuum panel. 
The liquid crystal mixture material that was sealed in the panel was 
divided into an area L with a left 89.degree. twisting orientation 112 and 
an area R with a right 89.degree. twisting orientation 113. Following 
this, the panel was irradiated for seven minutes by ultraviolet rays 
having a luminous intensity of 5 mW/cm.sup.2 (wavelength 350 nm) to 
polymerize the polymer. This step separated the polymer from the liquid 
crystal mixture material and the liquid crystal display device of the 
present embodiment as shown in FIG. 1A and FIG. 1B was completed. 
The liquid crystal 105 exhibited a state divided into a left 89.degree. 
twisting orientation area L and a right 89.degree. twisting orientation 
area R, the same as before ultraviolet ray irradiation. In addition, the 
fact that the polymer 104 and the liquid crystal 105 took on a structure 
that was mutually oriented and dispersed was verified by a polarizing 
microscope. 
FIG. 3 shows the electro-optical properties of the liquid crystal display 
device that was obtained by the present embodiment. The electro-optical 
properties exhibited threshold properties, and a normally black property 
was obtained wherein the reflectance increases by the voltage being 
applied. That is to say, when the voltage is off, a black display was 
obtained through the absorption of the bi-color pigment, and when a 
sufficient voltage was applied, the liquid crystal 105 was orientated in 
the direction of the electric field. Consequently, the orientation 
directions of the polymer and the liquid crystal differ, and points of 
discontinuity were created in the refractive index in the medium, so that 
a light scattering state was achieved. At this time, the absorption was 
extremely small because the bi-color pigment was also oriented in the 
direction of the electric field, so a white display was obtained. 
Next, the results of measurements of the electro-optical properties of the 
liquid crystal display device of the present embodiment will be shown. The 
electro-optical properties were measured by applying a 100 Hz rectangular 
wave on the liquid crystal display device using a xenon lamp ring light 
source. This causes light to be incident from all directions (360.degree.) 
from a direction inclined 30.degree. from the normal direction (panel 
normal) of the liquid crystal display device surface (incident angle 
30.degree.). The response of the reflected light of the incident light is 
detected in the normal direction. The detected surface area was 2 mm in 
diameter. The reflectance of 100% was standardized at the luminosity of 
the entire dispersion plate surface. Hereafter, the threshold voltage 
value V10 was defined to be the voltage value when the reflectance is 10 
with the maximum reflectance--minimum reflectance being standardized to 
100. The saturation voltage value V90 was defined to be the voltage value 
when the reflectance is 90. In addition, the scattering directivity 
measured the change in the reflectance in the panel normal direction using 
parallel light rays and with the angle .psi. between the parallel light 
rays and the panel normal and the panel rotation angle .phi. as 
parameters. With the liquid crystal display device of the present 
embodiment, V10 was 1.7 V, V90 was 3.2 V and the maximum reflectance was 
79%. In addition, with regard to the scattering directivity, the results 
of measurements when the saturation voltage 3.2 V was applied are shown in 
FIG. 4. In addition, the scattering directivity of a conventional liquid 
crystal display device having the same structure as the present embodiment 
but wherein orientation is not divided and only one direction is rubbed 
and only one direction out of left and right is caused to be twist 
oriented is shown in FIG. 5 with respect to left 89.degree. twist cells 
and right 89.degree. twist cells. In this conventional liquid crystal 
display device, where the orientation is not divided and only one 
direction is rubbed and only one direction out of left and right is caused 
to be twist oriented, twisting of at least 360.degree. is necessary in 
order to obtain scattering properties equal to those of the present 
embodiment, and in this case, V10 was 3.8 V and V90 was 6.5 V. 
As exhibited above, with the present embodiment, through a structure 
wherein a pixel is divided into areas in which the left and right twisting 
direction of the liquid crystal differs, the driving voltage was greatly 
reduced in a liquid crystal display device using a polymer dispersion 
liquid crystal in which the liquid crystal and polymer are mutually 
orientation dispersed. Furthermore, the maximum reflectance, which is an 
indicator of brightness, was high and the brightness was good. In 
addition, in the liquid crystal display device of the present embodiment, 
the scattering directivity was small and favorable, as shown in FIG. 4. 
Accordingly, changes in the brightness caused by the method of positioning 
the panel disappear in uniform lighting and in environments where the 
light is strong from a specific direction, and the visual properties, 
portability and visibility were improved. 
Second Embodiment 
Hereafter, with the present embodiment an example is presented using the 
same structure as in the first embodiment including the orientation 
divided in the pixels. Further, a two terminal device (MIM) is formed on 
each pixel electrode and a light-shielding layer is formed on the top 
substrate at a position between the pixels and corresponding to the 
orientation division boundary. FIG. 6A and FIG. 6B, respectively, show the 
cross-sectional view and planar view of the liquid crystal display device 
of the present embodiment. 
The bottom substrate 610 was a MIM substrate produced through a 2 photo 
process. In the substrate production process, Ta was sputtered and then 
was patterned (photo first procedure) into a desired shape. Then, the Ta 
was anodized and an insulating film of Ta.sub.2 O.sub.5 was formed on the 
Ta surface. Next, Cr was sputtered and then was patterned (photo second 
procedure) into a desired shape. Then, MIM devices 608 composed of 
Ta--Ta.sub.2 O.sub.5 --Cr and reflective pixel electrodes 609 composed of 
Cr were formed. 
On the other hand, ITO was sputtered on the top substrate 601 and was 
patterned into a stripe form, and an ITO electrode 602 was formed. Next, a 
black color resist that is used in the color filter was applied and 
patterned into the desired shape. A black stripe 603 was formed between 
the reflective pixel electrodes 609 and at a position corresponding to the 
orientation boundary in the reflective pixel electrodes. The black stripe 
at the orientation boundary had a width of 10 .mu.m. 
Next, Optomer AL3046 (produced by Japan Synthetic Rubber Co. Ltd.) was 
flexographed onto the two substrates 601 and 610 and then calcinated for 
one hour at 180.degree. C., and polyimide films 604 and 607, respectively, 
were formed. Similar to the first embodiment, the rubbing direction of the 
top substrate 601 was in one direction (613 in the drawing), and the 
bottom MIM substrate 610 was rubbed in two directions through mask 
rubbing, so that the rubbing direction was divided into two (611 and 612 
in the drawing). The division pitch corresponds to the pixel division, and 
the pixel pitch is 140.times.110 .mu.m. The two substrates thus obtained 
where bonded and anchored about the substrate perimeter with a separation 
of 5 .mu.m to produce a vacuum panel with a 5 inch diagonal. The rubbing 
axes of the top and bottom substrates 601 and 610 were respectively set at 
89.degree.. 
Next, a liquid crystal mixture material composed of a liquid crystal 
containing a bi-color pigment and a polymer precursor was vacuum sealed 
into the above-described vacuum panel, the same as in the first 
embodiment. The liquid crystal mixture material that was sealed into the 
panel was divided, the same as in the first embodiment, into an area L 
with a left 89.degree. twisting orientation 614 and an area R with a right 
89.degree. twisting orientation 615 corresponding to the mask pattern in 
each pixel. Following this, the panel was irradiated for 7 minutes by 
ultraviolet rays of luminous intensity of 5 mW/cm.sup.2 (wavelength 350 
nm), the polymer was separated from the liquid crystal mixture material, 
and the liquid crystal display device of the present embodiment as shown 
in FIG. 6A and FIG. 6B was completed. 
The liquid crystal 606 exhibited a state divided into a left 89.degree. 
twisting orientation area L and a right 89.degree. twist orientation area 
R, the same as before ultraviolet ray irradiation. In addition, the fact 
that the polymer 605 and the liquid crystal 606 took on a structure that 
was mutually oriented and dispersed was verified by a polarizing 
microscope. 
When the liquid crystal display device thus obtained was MIM driven with a 
1/480 duty, the maximum reflectance was 62% and the contrast ratio was 13 
under the measurement conditions of the first embodiment. In addition, 
light leaks from the liquid crystal response on the arrangement were 
blocked by the black stripe 603. Furthermore, the discrimination line of 
the orientation boundary was shielded from the light, and a uniform 
display was obtained. In addition, there was no directivity in the 
scattering when a voltage was applied, and a liquid crystal display device 
was obtained that possessed superior portability, visual properties and 
visibility. Furthermore, when a non-gray process and no-reflection coating 
were conducted on the surface of this liquid crystal display device, the 
pick up of the surroundings declined and the visibility improved 
dramatically. 
In addition, with the present embodiment, reflective electrodes were placed 
on the MIM substrate, but it is also possible to form reflective 
electrodes on the opposing substrate. 
Third Embodiment 
Hereafter, with the present embodiment an example is presented wherein a 
color filter is formed on the reflective electrodes in the structure of 
the second embodiment. FIG. 7 shows the cross-sectional view of the liquid 
crystal display device of the present embodiment. On the bottom substrate 
711, wiring and a MIM device 709 and reflective pixel electrodes 710 were 
formed, the same as in the second embodiment. Pigment color filters 708 
(red, green and blue) were formed at each pixel, respectively, on 
reflective pixel electrodes 710. On the other hand, an ITO electrode 702 
and a black stripe 703 were formed on the top substrate 701, the same as 
in the second embodiment. The black stripe at the orientation boundary had 
a width of 10 .mu.m. The liquid crystal display device of the present 
invention was completed using the above-described substrates 701 and 711, 
the same as in the second embodiment. The rubbing directions and 
orientation division pitches also had the same conditions as in the second 
embodiment. 
The liquid crystal display device thus obtained was such that a black 
display was obtained through absorption of the two-color pigment when the 
voltage was off, and a color display was obtained by applying voltages on 
each color pixel. 
In addition, when MIM driven at a 1/480 duty, the maximum reflectance was 
31% and the contrast ratio was 12 under the measurement conditions of the 
first embodiment. In addition, an 8 gradation display and 512 color 
display were possible. In addition, light leaks from the liquid crystal 
response on the arrangement were blocked by the black stripe. Furthermore, 
the discrimination line of the orientation boundary was shielded from the 
light, and a uniform display was obtained. In addition, there was no 
directivity in the scattering when a voltage was applied. A liquid crystal 
display device was obtained that possessed superior portability, visual 
properties and visibility. Furthermore, when a non-gray process and 
no-reflection coating were conducted on the surface of this liquid crystal 
display device, the pick up of the surroundings declined and the 
visibility improved dramatically. 
In the embodiments, reflective electrodes were placed on the MIM substrate, 
but it is also possible to place the reflective electrodes on the opposing 
substrate and to form color filters on the top thereof. 
In addition, the composition of the color filters used in the embodiments 
is not restricted to red, green and blue, and it is also possible to use 
compositions such that natural colors can be reproduced. In addition, the 
color filters can also be placed on the top substrate. 
This concludes the description of the embodiments of the present invention 
but the present invention is not limited to the above embodiments. 
For example, in first through third embodiments, a bi-color pigment is 
added to the liquid crystal, but it is not necessary to add the pigment. 
If the pigment is not added, the black level increases slightly when 
voltage is not applied. When voltage is applied, there is no light 
absorption by the pigment, so the maximum reflectance increases, and 
brightness improves. Also, when low-reflectance, reflecting electrodes are 
used, or when a light absorption layer is placed on the reflecting 
electrodes, there is no particular necessity to add a bi-color pigment. 
In addition, in the above-described embodiments 1 through 3, the structure 
described has twist angles of 89.degree., but this is intended to be 
illustrative and not limiting. The twist angle is preferably between 
45.degree. and 90.degree., and more preferably, between 70.degree. and 
90.degree.. When the twist angle is smaller than 45.degree., the 
scattering directivity is strong and the visual properties become poor. In 
addition, when 90.degree. is exceeded, a reverse twist domain is created. 
In the above-described embodiments 1 through 3, a polyimide film was used 
as the orientation film utilized in the parallel orientation process, but 
besides this, polyamide film, SiO oblique vaporization film, polyvinyl 
alcohol, or the like may also be suitably used. 
As the material used in the substrates, soda glass, quartz, non-alkali 
glass, silicon monocrystal, sapphire substrate, thermosetting polymer, 
thermoplastic polymer, or the like may be suitably used. The polymer 
material used in the substrates is not particularly limited as long as it 
does not have a negative effect on the liquid crystal and polymer 
contained between the substrates. PET, polyethyl sulfone, epoxy hardening 
resin, phenoxy resin, polyallyl ether or the like, may be suitably used. 
The reflective electrodes are Cr in the first through the third 
embodiments, but a metal such as Al, Cr, Mg, Ag, Au, Pt or the like, or 
alloys of these, may be effectively used. In particular, Cr or an Al--Mg 
alloy are preferable from the standpoint of stability and reflectance, and 
in the case of the Al--Mg alloy, it is desirable that Mg be added in the 
amount of 0.1 to 10% by weight. 
For the liquid crystal, what is normally used in liquid crystal display 
devices may be effectively used, but in order to improve the degree of 
scattering, it is desirable that the multiple refractivity anisotropy 
.DELTA.n of the liquid crystal is equal to or greater than 0.15. Also, in 
order to drive a non-linear device, it is desirable that the relative 
resistivity values of the liquid crystal alone to be equal to or greater 
than 1.0.times.10.sup.9 .OMEGA..multidot.cm, and more preferably, be equal 
to or greater than 1.0.times.10.sup.10 .OMEGA..multidot.cm in order to 
increase the retention rate and improve the display quality. 
As the bi-color pigment, it is preferable to use azo, anthraquinone, 
naphthoquinone, perylene, quinophthalone, azomethyn or the like which are 
normally used in the GH (guest-host) display format. Of these, in terms of 
light-resistance, it is particularly preferable to use anthraquinone alone 
or a mixture of anthraquinone with another pigment, as necessary. These 
bi-color pigments may be mixed depending on the color needed. 
As polymer precursors, any material can be used as long as it exhibits 
refractivity anisotropy after polymerization and the orientation disperses 
with the liquid crystal. From the standpoint of simplicity in the liquid 
crystal display device manufacture it is desirable to use an ultraviolet 
cured type monomer. For the ultraviolet cured type monomer, a 
monofunctional methacrylate, bifunctional methacrylate or multifunctional 
methacrylate are preferably used to improve the degree of scattering, it 
is desirable to include of these monomers, at least one benzene ring in 
the polymer structure. In particular, materials containing biphenyl, 
terphenyl or quarterphenyl lattice are desirable. These monomers may also 
contain a chiral component. Also, it is possible to irradiate these 
monomers with ultraviolet rays and polymerize them either alone or after 
mixing with other monomers. 
In addition, in above-described embodiments 2 and 3, a MIM devices was used 
as the two terminal non-linear device, but it is also possible to use 
besides MIM devices, lateral MIM devices, back-to-back MIM devices, MSI 
devices, diode-ring devices or varistor devices. In addition, naturally it 
is also possible to use three terminal non-linear devices, and as the 
three terminal non-linear devices, it is possible to use polysilicon TFT 
devices, amorphous silicon TFT devices, Cd--Se TFT devices or the like. 
INDUSTRIAL APPLICATIONS 
As described above, with the present invention it is possible to resolve 
the problems of visibility caused by driving voltage and scattering 
directivity that were conventionally problems in polymer dispersion type 
liquid crystal display devices that are bright, have no double images and 
do not require polarizing plates, said problems being resolved through a 
structure that mutually disperses the polymer and divides the twisting 
direction of the liquid crystal that is twist oriented within the pixels. 
In particular, the driving voltage of the liquid crystal display device of 
the present invention can adequately drive MIM devices and TFT devices 
because driving voltage has been reduced to being similar to that of the 
TN mode, and it is possible to greatly improve brightness and contrast. 
Through this, it becomes possible to improve the number of display colors 
and the visibility in the case of a reflective-type color liquid crystal 
display device. In addition the necessity of a high voltage-resistant 
driver disappears, and it is possible to reduce power consumption and 
costs. Accordingly, the present invention can be utilized in a 
reflective-type color liquid crystal display device that improves the 
number of display colors and the visibility and has low power consumption 
and low cost. 
Furthermore, with the liquid crystal display device of the present 
invention, the brightness, visual properties and visibility were improved 
by suppressing the scattering directivity. 
As a result, the present invention can be used in liquid crystal display 
devices suitable for portable applications for which numerous environments 
are predicted. In addition, the present invention can be used in 
reflective-type large capacity displays with active matrix driving, low 
power consumption and superior display quality.