Optical device

An optical device is provided which comprises a liquid layer containing a liquid-absorbable and releasable polymer that absorbs and releases a liquid under the action of an electric field and at least one pair of electrodes holding the liquid layer therebetween. The liquid may be colored, and alternatively the liquid-absorbable and releasable polymer may be colored.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an optical device for the use in display devices, 
light modulator devices, etc., and particalarly to a novel optical device 
utilizing the swelling and shrinking of gel under action of an electric 
field. 
2. Description of the Prior Art 
Non-luminous display devices have been regarded as important because they 
can produce natural color tone and do not cause any fatigue to human eyes, 
and they include, for example, electrochromic display devices (ECD), 
liquid crystal display devices (LCD), etc. However, their quality and 
performance are not satisfactory. For example, ECD is as low in display 
contrast that it is hardly observable in a dim place and discrimination of 
fine image is hard at a distance. 
On the other hand, LCD has such another disadvantage as a restricted angle 
of visual field, besides the above noted disadvantages. 
Similar problems exist even when they are used in the light modulator 
devices such as light shutters, etc. 
SUMMARY OF THE INVENTION 
An object of the present invention is to solve the problems in the prior 
art, and to provide a clear and improved optical device. 
Another object of the present invention is to provide a display device 
capable of producing a natural color tone and while eliminating fatigue to 
human eyes. 
Further object of the present invention is to provide an optical device 
that can be readily prepared and also utilized as a light modulator 
device. 
According to an aspect of the present invention, there is provided an 
optical device, which comprises a liquid layer containing a 
liquid-absorbable and releasable polymer that absorbs and releases a 
liquid by action of electric field, and at least one pair of electrodes 
holding the liquid layer therebetween. 
According to another aspect of the present invention, there is provided an 
optical device, which comprises a liquid layer containing a 
liquid-absorbable and releasable polymer that absorbs and releases a 
liquid by action of electric field and a colored liquid, and at least one 
pair of electrodes holding the liquid layer therebetween. 
According to a further aspect of the present invention, there is provided 
an optical device, which comprises a liquid layer contianing a 
liquid-absorbable and releasable colored polymer that absorbs and releases 
a liquid by action of an electric field, and at least one pair of 
electrodes holding the liquid layer therebetween.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The optical device according to the present invention has a broad meaning 
including a display device, a light modulator device, etc. 
The present invention will be described in detail below, referring to the 
drawings. 
FIG. 1 is a view showing a schematic structure of an optical device of a 
transmission type according to the present invention, where numeral 1 
shows a substrate, 2 a gel-containing liquid layer, 3 a transparent 
protective plate, 7 an image element electrode or signal electrode (which 
will be hereinafter referred to merely as "image element electrode"), and 
8 a counter electrode. The optical device is constituted of laminated 
layers, as shown in the drawings. 
The substrate 1 includes a transparent substrate, for example, glass, 
plastic, etc., and an intransparent substrate, for example, metal such as 
silicon wafer, a ceramic, aluminum, etc., and an opaque plastic., etc. The 
same materials as for the transparent substrate are used for the 
transparent protective plate 3. 
The gel-containing liquid layer 2 is a layer containing a liquid and a 
liquid-absorbable and releasable polymer. 
The term "gel" used in the present invention means a state of a 
liquid-absorbable and releasable polymer (reticular polymer) containing a 
liquid. The polymer for use in the present invention has a property of 
absorbing and releasing a liquid under the action of an electric field. 
The liquid-absorbable and releasable polymer having such a property can be 
classified into two major groups, one of which belongs to polymers which 
will absorb a liquid under action of an electric field to undergo swelling 
and which will release the liquid by eliminating the electric field (or by 
applying an inversed electric field under a special condition) to undergo 
shrinking. These may include, for example, electrically chargeable 
polymers obtained from an acrylamide derivative as the main component and 
a cross-linkable monomer, such as Enzafix P-SH (tredemark of a product 
made by Wako Junyaku K.K. Japan), polymers obtained from as 
N-isopropylacylamide deviative as the main component and a cross-linkable 
monomer, such as isopropylacrylamide-acrylic acid-divinylbenzene 
copolymer, etc. The second major group of polymers is one which will 
release a liquid under action of an electric field to undergo shrinking, 
and will absorb the liquid on eliminating the electric field (or by 
applying an inversed electric field under a special condition. This group 
may include, for example, electrically chargeable polymers obtained from 
an acrylamide derivative as the main component and a cross-linkable 
monomer, such as Enzafix P-SH (trademark of a product made by Wako Junyaku 
K.K., Japan) or polymers obtained from an N-isopropylacylamide derivative 
as the main component and a cross-linkable monomer, such as an 
isopropylacrylamideacrylic acid-divinylbenzene copolymer, etc. 
The liquid to be filled in the gel-containing liquid layer 2 includes 
water, organic solvents such as methanol, ethanol, acetone, acrylonitrile, 
dimethylformamide, pyridine, dimethylsulfoxide, hexamethylphosphamide, 
dimethylacetamide, etc. and their mixture. 
When a colored liquid is used in the gel-containing liquid layer 2 to 
enhance the contrast or change the color tone (FIG. 3), a solution or 
dispersion of a coloring material in the said solvent is used, where it is 
necessary that the coloring material does not penetrate into the gel owing 
to any physical or chemical factor. 
The coloring material includes, for example, dyes such as poly A-133, Poly 
R-478, Poly S-119, Poly T-128 (all the foregoing products being made by 
Dinapole Co.), Seikagen W-Blue-BK 1600, Seikagen W-Blue-1300 (all the 
foregoing products being made by Dainichi Seika K.K., Japan), and pigments 
such as Benzidine yellow-GR, Chromophthal Orange 4R, toluidine Maroon 
MT-2, vulkan Fast Orange GG, Permanent Red F5R, Lithol Rubin GK, Brilliant 
Carmine 3B, Sanyo Red B-G511, Monastral maroon Permanent Red E5B, 
permanent Pink E, Phthalocyanine Blue, Phthalocyanine green, Naphthol 
Green BN, Diamond black etc. 
When a colored polymer is used (FIG. 4) the coloring material needs to be 
confined in the network of the reticular polymer or the inside surface 
thereof. 
The coloring material can be confined therein by chemical binding, i.e. by 
chemically binding the coloring material with a reticular polymer, or by 
enclosing macromolecules in the polymer network by three dimensional 
cross-linking reaction in the presence of macromolecules of coloring 
material. The coloring material herein used includes reactive dyes such as 
Diamira yellow G, sumifix Red B, Diamira Brilliant Green 6B, Celmazol 
Brilliant Blue G, etc. beside the above-mentioned coloring materials. 
When polymer that absorbs a liquid under action of an electric field and 
releases the liquid on elimination of the electric field is used in the 
present invention, it is preferable that the gel particles in the 
gel-containing liquid layer 2 are so small as to show good light 
scattering and refracting properties or have fine irregularity on the 
surface, without any restriction to the shape, arrangement, number, etc. 
It is preferable that the gel or an assembly of fine gel particles is 
provided in accodance with the shape, size or arrangement of image 
elements or apertures(which will be hereinafter refered to merely as 
"image elements"). The volume occupied by one gel particle must be 
significantly smaller than the image element space (namely, the image 
component area multiplied by the thickness of the gel-containing liquid 
layer), and is preferably not more than 1/3 of image component space. 
The gel is preferably fixed to one of a pair of electrodes by a chemical or 
physical means. 
When polymers that releases a liquid by action of an electric field and 
absorb the liquid in the absence of electric field are used, the size, 
shape and arrangement of gel in the gel-containing liquid layer can be 
selected as desired. The gels can be filled, as integrated, in the 
gel-containing liquid layer 2, or can be filled therein a state of cracked 
mass, dispersion or block. 
Gel or an assembly of fine gel perticles can be provided in accordance with 
the shape, arrangement, etc. of image element or apertures(which will be 
hereinafter referred to as "image element"), Generally, the size of one 
gel particle is preferably approximately equal to that of the image 
element. The thickness of gel-containing liquid layer 2 is preferably 1 to 
1,000 .mu.m, more preferably 1 to 100 .mu.m. 
Image element electrodes (7-1) and (7-2) are provided on the substrate (or 
transparent protective plate 3) in accordance with the image element, and, 
if necessary, can take any shape, such as segment, stripe, dot matrix, 
etc. The length at one side of the image element electrodes (7-1) and 
(7-2) is preferably 10 .mu.m to 1 cm, more preferably 50 .mu.m to 1,000 
.mu.m in the case of the dot matrix shape. A Transparent electrode such as 
indium-tin oxide (I.T.O), etc. can be used, if required. 
The counter electrode 8 is provided on the transparent protective plate 3 
(or substrate) to face the image element electrodes (7-1) and (7-2) 
through the gel-containing liquid layer 2, and can be a transparent 
electrode, if required. 
Image formation or light modulation principle according to the present 
invention will be described below, referring to FIG. 1 showing an optical 
device of a transmission type. 
When a switch (5-2) is off, i.e., when no electric field is applied to gel 
(4-2) in contact with an image element electrode (7-2), the gel (4-2) 
stays in a very minute shrunk state. Thus, the light (9-2) introduced into 
the gel (4-2) is scattered or refracted by the gel (4-2), and its 
rectilinear propagation is inhibited, because the gel in the very, small 
state has light-scattering and refracting properties. 
On the other hand, when a switch (5-1) is on, i.e., when gel (4-1) is under 
action of electric field, the reticular polymers of the gel are negatively 
charged, and thus are pulled toward the electrode 8. Consequently, the gel 
undergoes swelling to the state (4-1). As a result of swelling, th 
light-scattering and refracting properties of the gel are lost, and the 
light (9-1) can propagate rectilinearly therethrough. through. 
In the case of reticular polymers that are positively charged in the 
liquid, similar function and effect can be also obtained by reversing the 
polarity of the electrode in FIG. 1. 
When the switoh (5-1) is off, the gel shrinks and returns to the original 
state, because the reticular polymer molecules are made longer under the 
action of electric field than the equilibrium length, and can gain a 
negative presure, i.e. a restoring force when the electric field is 
eliminated. As a result, the light introduced thereinto is scattered or 
refracted again, and its rectilinear propagation is inhibited. When a 
reversed electric field is further applied thereto, then the shrinking 
speed can be accelerated. 
The present invention is based on an application of this principle to an 
optical device, where an optical difference is produced by electrically 
controlling swelling and shrinking of a gel, thereby obtaining a display 
or light modulation. 
The foregoing description has been made of an optical device of 
transmission type, and the same principle is also applicable to an optical 
device of reflection type (not shown in the drawing). 
FIG. 2 shows an embodiment of a polymer that can release a liquid by action 
of an electric field to undergo shrinking and can absorb the liquid in the 
presence of electric field to undergo swelling. 
When a switch (5-2) is off, i.e., when the gel (4-2) in contact with an 
image element electrode (7-2) is not under the action of electric field, 
the gel remains swollen (4-2). Thus, the light (9-2) introduced into the 
gel (4-2) can pass through the gel-containing liquid layer 2 without an 
scattering or refraction by the gel (4-2). 
On the other hand, when a switch (5-1) is on, i.e., when the swollen gel is 
under the action of an electric field. the reticular polymers of gel are 
pulled toward the electrode (7-1) because the reticular polymers are 
negatively charged, and undergoes shrinking into gel (4-1). Thus, the 
light (9-1) introduced into the gel (4-1) undergoes scattering or 
refraction, and its rectilinear propagation is inhibited, because the gel 
in a very small state has light scattering and refracting properties. 
When minute gel particles are densely filled. gaps are formed within the 
gel owing to the diminution of gel perticles, and similar optical effect 
can be obtained. Furthermore, a similar function and effect can be 
obtained with reticular polymers that can be positively charged in the 
liquid, where they are shrunk to the opposite side to that of FIG. 2, that 
is, the side of counter electrode 8. 
When the switch 5-1 is turned off, the gel undergoes swelling and returns 
to the original state. 
The reticular polymer molecules are compressed to less than the equilibruim 
length under the action of an electric field, and thus a positive 
pressure, i.e. a restoring force, can be gained by removing the electric 
field. As a result, light can pass through the gel-containing liquid layer 
2 without any scattering or refraction. When a reversed electric field is 
further applied thereto, then the swelling speed can be accelerated. 
FIG. 3 shows another embodiment of using a colored liquid in the 
gel-containing liquid layer, where the image formation or light modulation 
takes place as follows. 
When a switch (5-2) is off, i.e., when gel (4-2) in contact with an image 
component electrode (7-2) is not under the action of electric field, the 
gel (4-2) is maintained in a shrunk condition in a very small state. Thus, 
the light (9-2) introduced into the gel (4-2) and its neighborhood is 
absorbed by the colored liquid in the gel-containing liquid layer or 
partially absorbed thereby, and weakened. 
On the other hand, when a switch (5-1) is on, i.e., when the gel is under 
the action of an electric field, the reticular polymers of gel are pulled 
toward the positively charged electrode 8, because the polymers are 
negatively charged. Thus, the gel (4-1) is swollen until it contacts or 
approaches the electrode 8. As a result, the colored liquid retreats by 
the amount of swelling of the gel, and the light (9-1) put therein can 
pass through the gel-containing liquid layer 2. 
Even when positively chargeable reticular polymers in the liquid are used, 
similar function and effect can be obtained by reversing the polarity of 
the electrode shown in FIG. 3. 
When the switch (5-1) is turned off, the gel undergoes shrinking and 
returns to the original state. The reticular polymer molecules are made 
longer than the equilibrium length under the action of the electric field, 
and a negative pressure, that is, a restoring force, can be gained by 
eliminating the electric field. As a result, the light put therein 
scattered or refracted again, and its rectilinear propagation is 
inhibited. When a reversed electric field is further applied thereto, then 
the shrinking speed can be accelerated. 
Light modulation with a colored polymer will be described, referring to 
FIG. 4. 
When a switch (5-2) is off, i.e., when colored gel (4-2) in contact with an 
image component electrode (7-2) is not under the action of electric field, 
the colored gel (4-2) stays in a very small shrunk state. Thus, the light 
(9-2) introduced into the colored gel (4 2) is scattered or absorbed by 
the colored gel, or partially scattered or absorbed, and weakend. 
On the other hand, when a switch (5-1) is on, i.e., when the colored gel is 
under the action of electric field, the reticular polymers of colored gel 
are pulled toward the positively charged electrode 8, because the polymers 
are negatively charged, and the colored gel (4-1) undergoes swelling when 
it contacts or approaches the electrode 8. As a result, the coloring 
material is diluted corresponding to the amount of swelling of the colored 
gel, and the light (9 1) introduced thereinto can pass through the 
gel-containing liquid layer 2 without any inhibition. 
Even when positively chargeable reticular polymers in the liquid are used, 
similar function and effect can be obtained by reversing the polarity of 
the electrode in FIG. 4. 
When the switch (5-1) is turned off, the colored gel undergoes shrinking 
and returns to its original condition. The reticular polymer moecules are 
made longer than the equilibrium length under the action of the electric 
field, and a negative pressure, that is, a restoring force, is gained by 
removing the electric field. As a result, the light put therein is 
scattered or refracted again, and its rectilinear propagation is 
inhibited. When a reversed electric field is further applied thereto, then 
the shrinking speed can be accelerated. 
The foregoing description has been made on an optical device of a 
transmission type, and the same principle is also applicablc to an optical 
device of a reflection type. 
In the case of polymers that can release a liquid by action of electric 
field and can absorb the liquid in the absence of electric field, the 
dominant light modulation principle is basically the same as described 
above, though the function is quite contrary thereto. 
The present invention will be described in detail below, referring to 
Examples. 
EXAMPLE 1 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
0.75 g of acrylamide, 0.2 g of sodium acrylate, 0.02 g of 
N,N-methylenebisacrylamide, and 50 .mu.l of tetramethylethylenediamine 
were dissolved in 14 ml of water. 
Separately, 0.02 g of ammonium persulfate was dissolved in 1 ml of water, 
the thus prepared solution was mixed with the first solution. Than, the 
obtained monomer solution was immediately added to 100 ml of liquid 
paraffin containing 1 ml of sorbitan trioleate, and vigorously stirred in 
a nitrogen atmosphere. 
After completion of polymerization, the thus formed polymers were washed 
with hexane to remove the liquid paraffin therefrom, and then poured into 
acetone to coagulate. Then, washing of the polymers was repeated 
alternately with an aqueous 50% acetone solution and an aqueous 70% 
acetone solution, and finally, tho polymers were dispersed in an aqueous 
50% acetone solution. 
A glass plate, 50.times.50 mm, patternwise vapordeposited with a 
semi-transparent platinum film having a thickness of 150 .ANG. as an anode 
and a nickel plate, 50.times.50 mm, as a cathode were immersed in the 
polymer dispersion, and a predetermined voltage was applied therebetween 
to coagulate the polymer particles on the platinum pattern. 
The thus obtained glass plate and another glass Plate with a 
2000.ANG.-thick I.T.O film were confronted with each other, and an aqueous 
60% acetone solution was filled in the clearance between the glass plates, 
using a Mylar film (trade name of a polyester supplied by Du Pont) having 
a thickness of 20 .mu.m as a spacer. 
Display and light modulation 
When a voltage of 0.8 to 5V was applied between the platinum semi 
transparent electrode as a cathode and the I.T.O electrode as an anode in 
the thus prepared optical device, the gel between the electrodes was 
swollen to show a light transmissivity 
On the other hand, when the switch was turned off, the gel shrank and 
recovered the milk-white color and opacity. 
As a result of repeated tests, the reproducibility was confirmed. Thus, the 
display function and the light modulation function were confirmed. 
EXAMPLE 2 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
0.75 g of acrylamide, 0.25 g of sodium methacrylate, 0.02 g of 
N,N-methylenebisacrylamide, and 50 .mu.l of tetramethylethylenediamine 
were dissolved in 14 ml of water. 
Separately, 0.02 g of ammonium persulfate was dissolved in 1 ml of water, 
and the thus prepared solution was added to the first solution. Then, the 
thus obtained monomer solution was immediately added to 100 ml of liquid 
paraffin containing 1 ml of sorbitan trioleate and vigorously stirred in a 
nitrogen atmosphere. 
After completion of polymerization, the thus formed polymer was washed with 
hexane to remove the liquid paraffin therefrom, and then poured into 
acetone to coagulate. Then, washing of the polymers was repeated 
alternately with an aqueous 40% acetone solution and with an aqueous 70% 
acetone solution, and finally the polymers were dispersed in an aqueous 
45% acetone solution. 
A glass plate, 50.times.50 mm, patternwise vapor deposited with a platinum 
semi-transparent film having a thickness of 150 .ANG. as an anode and a 
nickel plate, 50.times.50 mm, as a cathode were dipped in the polymer 
dispersion, and a predetermined voltage was applied therebetween to 
coagulate the polymer particles on the platinum pattern. 
The thus obtained glass plate and a glass plate having an I.T.O film having 
a thickness of 2,000 .ANG. were confronted with each other, and an aqueous 
60% acetone solution was filled in the clearance between the glass plates, 
using a Mylar film having a thickness of 20 .mu.m as a spacer. 
Display and light modulation 
The same results as in Example 1 were obtained, when tested in the same 
manner as in Example 1. 
EXAMPLE 3 
Preparation of an Optical Device 
The present optical device was prepared in the following manner. 
0.75 g of acrylamide, 0.2 g of sodium acrylate, 0.02 g of 
N,N-methylenebisacrylamide, and 50 .mu.l of tetramethylethylenediamine 
were dissolved in 14 ml of water. 
Separately, 0.02 g of ammonium persulfate was dissolved in 1 ml of water, 
and the thus prepared solution was added to the first solution. Then, the 
thus obtained monomer solution was immediately added to a solvent mixture 
of 23 ml of chloroform, 75 ml of toluene 1 ml of sorbitan trioleate, and 
vigorously stirred in a nitrogen atmosphere. 
After completion of polymerization, the thus obtained polymers were washed 
with hexane and then poured into acetone to coagulate. Then, washing of 
the polymers was repeated alternately with an aqueous 50% acetone solution 
and an aqueous 70% acetone solution, and finally the polymers were 
dispersed in an aqueous 50% acetone solution. 
The thus prepared polymer dispersion was sealed in between a glass plate 
patternwise provided with an I.T.O electrode having a thickness of 2,000 
.ANG. by sputtering and another glass plate vapor-deposited with a 
platinum having a thickness of 150 .ANG., using a Mylar film having a 
thickness of 20 .mu.m as a spacer. 
Display and light modulation 
When a voltage of 0.8 to 5V was applied between the platinum semi-conductor 
electrode as a cathode and the I.T.O electrode as an anode in the thus 
prepared optical device, the gel existing between the electrodes shrank 
and became milk-white and opaque 
On the other hand, when the switch was turned off, the gel underwent 
swelling and recovered the original transmissivity. 
As a result of repeated tests, the reproducibility was confirmed. The 
display function and the light modulation function were thus confirmed. 
EXAMPLE 4 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
0.75 g of acrylamide, 0.20 g of sodium acrylate, 0.02 g of 
N,N-methylenebisacrylamide, and 50 .mu.l of tetramethylethylenediamine 
were dissolved in 14 ml of water. 
Separately, 20 mg of ammonium persulfate was dissolved in 1 ml of water, 
and the thus prepared solution was mixed with the monomer solution. Then, 
the mixture was poured into a solvent mixture of 25 ml of carbon 
tetrachloride, 75 ml of toluene and 1 ml of sorbitan trioleate and 
vigorous stirred in a nitrogen atmosphere. 
After completion of polymerization, the thus formed polymers were 
thoroughly washed with hexane, and then with acetone to coagulate. Then, 
washing of the polymers was repeated alternately with an aqueous 50% 
acetone solution and with an aqueous 70% acetone solution, and finally the 
polymers were dispersed in an aqueous 50% acetone solution. 
A glass plate, 50.times.60 cm, patternwise vapor-deposited with a platinum 
semi-transparent film having a thickness of 150 .ANG. as an anode and a 
nickel plate as a cathode were dipped in the polymer gel dispersion, and a 
voltage of 0.8V was applied therebetween to coagulate the polymer gel on 
the platinum pattern. 
The gel-coagulated platinum electrode as a cathode and a glass plate, 
50.times.60 mm, provided with an I.T.O film having a thickness of 2,000 
.ANG. on the entire surface by sputtering as an anode were confronted with 
each other while inserting a Mylar film having a thickness of 20 um as a 
spacer therebetween. 
An aqueous 60% acetone solution containing Brilliant Carmine 3B (C.I. 
Pigment Red 60: C.I. 16015-Lake) as dispersed in a ball mill, was filled 
in the clearance between the electrodes to prepare an optical device. 
Display and light modulation 
When a voltage of 0.8 to 5V was applied between the platinum 
semi-transparent electrode as a cathode and the I.T.O electrode as an 
anode in the thus prepared optical device, the gel between the electrodes 
underwent swelling and showed light transmission. 
On the other hand, when the switch was turned off to eliminate to applied 
voltage the gel shrank and recovered the color of the colored liquid. 
As a result of repeated tests, the reproducibility was confirmed. The 
display action and the light modulation action were thus confirmed. 
EXAMPLE 5 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
0.75 g of acylamide, 0.20 g of sodium acrylate, 0.02 g of N,N 
methylenebisacrylate, and 50 ul of tetramethylethylenediamine were 
dissolved in 14 ml of water. 
Separately, 20 mg of ammonium persulfate was dissolved in 1 ml of water, 
and the thus prepared solution was mixed with the monomer solution. Then, 
the mixture was immediately poured into a mixture of 100 ml of liquid 
paraffin and 1 ml of sorbitan trioleate. and vigorously stirred in a 
nitrogen atmosphere. 
After completion of polymerization, the thus formed polymers were 
thoroughly washed with hexane, and then with acetone to coagulate. Then, 
washing of the polymers was repeated alternately with an aqueous 50% 
acetone solution and an aqueous 70% acetone solution, and finally the 
polymers were dispersed in an aqueous 50% acetone solution. 
A glass plate, 50.times.60 mm, patternwise vapor-deposited with a platinum 
semi-transparent film having a thickness of 150 .ANG. as an anode and a 
nickel plate as a cathode were dipped in the polymer gel dispersion, and a 
voltage of 0.8V was applied therebetween to coagulate the polymer gel on 
the platinum pattern. 
The gel-coagulated platinum electrode as a cathode and a glass plate, 
50.times.60 mm, provided with an I.T.O film having a thickness of 2,000 
.ANG. on the entire surface by sputtering as an anode were confronted with 
each other while inserting a Mylar film having a thickness of 20 .mu.m 
therebetween as a spacer. 
An aqueous 60% acetone solution containing Brilliant Carmine 3B (C.I. 
Pigment Red 60: C.I. 16015-Lake), as dispersed in a ball mill, was filled 
in the clearance between the electrodes to prepare an optical device. 
Display and light modulation 
The same results as in Example 4 were obtained, when tested in the same 
manner as in Example 4. 
EXAMPLE 6 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
0.75 g of acrylamide, 0.25 g of sodium methacrylate, 0.02 g of 
N,N-methylenebisacrylamide, and 50 .mu.l of tetramethylethylenediamine 
were dissoled in 14 ml of water. 
Separately, 20 mg of ammonium persulfate was dissolved in 1 ml of water, 
and the thus prepared solution was mixed with the monomer solution. Then, 
the mixture was immediately poured into a solvent mixture of 25 ml of 
carbon tetrachloride, 75 ml of toluene and 1 ml of sorbitan trioleate and 
vigorously stirred in a nitrogen atmosphere. 
After completion of polymerization, the thus formed polymers were 
thoroughly washed with hexane, and then with acetone to coagulate. Then, 
washing of the polymers was repeated alternately with an aqueous 45% 
acetone solution and with an aqueous 70% acetone solution, and finally the 
polymers were swollen in an aqueous 50% acetone solution containing Vulkan 
Fast Orange GG (C.I. Pigment Orange 14: C.I. 21165), as dispersed in a 
ball mill. 
A glass plate patternwise provided with an I.T.O electrode having a 
thickness of 2,000 .ANG. by sputtering and a glass plate vapor-deposited 
with platinum having a thickness of 150 .ANG. were confronted with each 
other with the respective electrodes being positioned inwardly, using a 
Mylar film having a thickness of 20 um as a spacer, and the said colored 
slurry was filled in the clearance between the electrode. 
Display and light modulation 
When a voltage of 0.8 to 5V was applied between the platinum 
semi-transparent electrode as a cathode and the I.T.O electrode as an 
anode in the thus prepared optical device, the gel existing between the 
electrodes underwent shrinking, and the space left by shrinking was 
occupied by the colored liquid, and showed the color of the colored 
liquid, when viewed from the side of the transparent protective plate 3. 
On the other hand, when the switch was turned off to eliminated opplied 
voltage, the gel underwent swelling and showed the original light 
transmissivity. 
As a result of repeated tests, the reproducibility was confirmed. 
The display action and the light modulation action were thus confirmed. 
EXAMPLE 7 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
On an ice bath, 0.75 g of acrylamide, 0.15 g of acrylic acid 0.02 g of 
N,N-methylenebisacrylamide, 20 .mu.l of tetramethylethylenediamine, and 10 
mg of ammonium persulfate were dissolved in a colored liquid containing 50 
mg of Monastral Red (C.I. Pigment violet 19: C.I. 46500) dispersed in 14 
ml of water in a ball mill. After nitrogen purge, polymerization was 
carried out at 20.degree. C. 30 ml of water was added to the thus formed 
colored gel, and the mixture was pulverized in an emulator 
Then, the colored gel was washed alternately with an aqueous 70% acetone 
solution and with an aqueous 50% acetone solution, and finally dispersed 
in an aqueous 50% acetone solution to make a slurry. 
A glass plate, 50.times.60 mm. patternwise vapor-deposited with a 
semi-transparent platinum film as an anode and a nickel plate as a cathode 
were dipped in the slurry at an inter-electrode distance of 0.3 mm, and a 
voltage of 0.8V was applied to deposit the gel on the platinum electrode. 
The glass electrode and another glass electrode provided with an I.T.O film 
having a thickness of 2,000 .ANG. on the entire surface were confronted 
with each other, while inserting a Mylar film having a thickness of 10 
.mu.m as a spacer, and an aqueous 65% acetone solution was filled in the 
clearance between the electrodes. 
Display and light modulation 
When a voltage of 0.8 to 5V was applied between the platinum 
semi-transparent electrode as a cathode and the I.T.O electrode as an 
anode in the thus prepared optical device, the colored gel existing 
between the electrodes underwent swelling and showed a light 
transmissivity. 
On the other hand, when the switch was turned off to eliminate the applied 
voltage the colored gel shrank and the original opacity was recovered. As 
a result of repeated tests, the reproducibility was confirmed. The display 
action and the light modulation action were confirmed. 
EXAMPLE 8 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
In an ice bath, 0.75 g of acrylamide, 0.18 g of methacrylic acid, 0.02 g of 
N,N-methylenebisacrylamide, 20 .mu.l of tetramethylethylenediamine, and 10 
mg of ammonium persulfate were dissoled in a colored liquid containing 50 
mg of Monastral Red (C.I. Pigment violet 19: C.I. 46500) dispersed in 14 
ml of water in a ball mill. After nitrogen purge, polymerization was 
carried out at 20.degree. C. 30 ml of water was added to the thus formed 
colored gel, and then the mixture was pulverized in an emulator. 
The colored gel was washed alternately with an aqueous 75% acetone solution 
and with an aqueous 45% accetone solution, and finally dispersed in an 
aqueous 45% acetone solution to make a slurry. 
A glass plate, 50.times.60 mm, pattenwise vapor-deposited with a 
semi-transparent platinum film having a thickness of 150 .ANG. as an anode 
and a nickel plate as a cathode were dipped in the slurry at an 
inter-electrode distance of 0.3 mm, and a voltage of 0.8V was applied 
therebetween to deposit the gel on the platinum electrode. 
The glass electrode and a glass electrode provided with an I.T.O film 
having a thickness of 2,000 .ANG. on the entire surface were confronted 
with each other while inserting a Mylar film having a thickness of 10 
.mu.m as a spacer, and an aqueous 65% acetone solution was filled in the 
clearance between the electrodes. 
Display and light modulation 
The same results as in Example 7 were obtained, when tested in the same 
manner as in Example 7. 
EXAMPLE 9 
Preparation of an optical device 
The present optical device was prepared in the following manner. 
On an ice bath, 0.75 g of acrylamide, 0.15 g of acrylic acid, 0.02 g of 
N,N-methylenebisacrylamide, 20 .mu.l of tetramethylethylenediamine, and 10 
mg of ammonium persulfate were dissoled in a colored liquid containing 60 
mg of Diamond Black (C.I. Pigment Black 1: C.I. 50440) dispersed in 14 ml 
of water in a ball mill. After nitrogen purge, polymerization was carried 
out at 20.degree. C. and 30 ml of water was added to the thus formed 
colored gel, and then the mixture was pulverized in an emulator. 
The colored gel was washed alternately with an aqueous 90% methanol 
solution and with an aqueous 50% methanol solution, and finally dispersed 
in an aqueous 57% methanol solution to make a slurry. 
A glass plate, 50.times.60 mm, patternwise vapor-deposited with a 
semi-transparent platinum film having a thickness of 150 .ANG. and a glass 
plate deposited with an I.T.O electrode having a thickness of 2,000 .ANG. 
by sputtering were confronted with each other while inserting a Mylar film 
having a thickness of 20 .mu.m as a spacer therebetween, and the slurry 
was filled in the clearance between the electrodes. 
Display and light modulation 
When a voltage of 0.8 to 5V was applied between the platinum 
semi-transparent electrode as a cathode and the I.T.O electrode as an 
anode in the thus prepared optical device, the colored gel existing 
between the electrodes underwent shrinking, and the light put therein was 
absorbed. 
On the other hand, when the switch was turned off to remove the applied 
voltage, the gel underwent swelling and recovered the original light 
transmissivity. As a result of repeated tests, the reproducibility was 
confirmed. The display function and the light modulation function were 
confirmed. 
Effects 
The main effects of the present invention are summarized as follows: 
(1) Gel particles can be reduced in size to any minute dimension, and thus 
an output or an image with a clear and high resolving power can be 
obtained. 
(2) Gel can be readily prepared, and thus an optical device can be readily 
prepared. 
(3) There is no limit to the angle of visible field, and thus observation 
is possible at any angle. 
(4) various coloring pigments can be used, and thus rich color display can 
be obtained.