U.S. patent application number 09/814222 was filed with the patent office on 2001-12-13 for flexible displays.
This patent application is currently assigned to Xerox Corporation. Invention is credited to Mikkelsen, James C. JR., Sacripante, Guerino G..
Application Number | 20010051263 09/814222 |
Document ID | / |
Family ID | 21883200 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010051263 |
Kind Code |
A1 |
Sacripante, Guerino G. ; et
al. |
December 13, 2001 |
Flexible displays
Abstract
A display comprised of a first component containing spheres
encapsulated within a wax, and thereover and thereunder said
component substrates.
Inventors: |
Sacripante, Guerino G.;
(Oakville, CA) ; Mikkelsen, James C. JR.; (Los
Altos, CA) |
Correspondence
Address: |
Patent Documentation Center
Xerox Corporation
Xerox Square 20th Floor
100 Clinton Ave. S.
Rochester
NY
14644
US
|
Assignee: |
Xerox Corporation
|
Family ID: |
21883200 |
Appl. No.: |
09/814222 |
Filed: |
March 21, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09814222 |
Mar 21, 2001 |
|
|
|
09035518 |
Mar 5, 1998 |
|
|
|
6235395 |
|
|
|
|
Current U.S.
Class: |
428/338 ;
427/212; 427/222; 427/430.1; 428/426; 428/500 |
Current CPC
Class: |
Y10T 428/268 20150115;
Y10T 428/2993 20150115; B32B 27/40 20130101; Y10T 428/2998
20150115; B32B 27/38 20130101; Y10T 428/2996 20150115; B32B 27/34
20130101; B32B 27/06 20130101; Y10T 428/31801 20150401; G02B 26/026
20130101; Y10T 428/2991 20150115; Y10T 428/31855 20150401; B32B
27/36 20130101 |
Class at
Publication: |
428/338 ;
428/500; 428/426; 427/212; 427/222; 427/430.1 |
International
Class: |
B05D 007/00; B05D
001/18 |
Claims
What is claimed is:
1. A display comprised of a first component containing spheres
encapsulated within a wax, and thereover and thereunder said
component a substrate.
2. A display device comprised of a first substrate containing
bichromal spheres encapsulated with a wax, and wherein said first
substrate is situated between a second substrate and a third
substrate.
3. A display device in accordance with claim 2, wherein the first
substrate is elastomer or plastic.
4. A display device in accordance with claim 2, wherein the second
substrate is an indium tin oxide coated glass or a polyester of
polyethylene-terephthalate.
5. A display in accordance with claim 3, wherein said second
substrate is indinium tin oxide.
6. A display device in accordance with claim 2, wherein the
bichromal sphere is from about 5 to about 25 microns in diameter,
and is comprised of one hemisphere colored white, and the remaining
hemisphere coated with a color other than white.
7. A display in accordance with claim 6, wherein said color other
than white is black, blue, red, yellow, cyan, green, magenta,
orange, green, or mixtures thereof.
8. A display device in accordance with claim 1, wherein the spheres
are encapsulated in a wax comprised of a hydrocarbon.
9. A display device in accordance with claim 2, wherein the wax is
a transparent linear hydrocarbon or a branched hydrocarbon each
with from about 18 to about 1,000 carbon atoms.
10. A display device in accordance with claim 2, wherein the first
substrate is an elastomer of polydimethylsiloxane or a
polyurethane.
11. A display device in accordance with claim 2, wherein the first
substrate is a plastic of an epoxy resin, a polyester resin, a
polyamide resin, a polystyrene-(meth)-acrylate resin, a
polydimthylsiloxane, or a polyurethane.
12. A display device in accordance with claim 2, wherein the second
and third substrate is a conductive glass.
13. A display device in accordance with claim 2, wherein the second
substrate is a conductive plastic of a polyester resin coated with
indinium tin oxide.
14. A process for the preparation of the wax encapsulated bichromal
spheres comprising (a) solubilizing a wax in an organic solvent;
(b) suspending bichromal spheres in said organic solvent; (c)
adding thereto a second solvent which precipitates or coacervates
the wax onto each of said bichromal spheres; and (d) optionally
isolating the wax encapsulated spheres.
15. A process in accordance to claim 14, wherein the wax is a
linear or branched hydrocarbon with about 18 to about 1,000 carbon
atoms.
16. A process in accordance to claim 14, wherein the wax has a
melting point of from about 15 degrees Centigrade to about 80
degrees Centigrade.
17. A process in accordance to claim 14, wherein the organic
solvent is hexane, heptane, octane, nonane, decane, dodecane,
Isopar, tetrahydrofuran, diethyl ether, chloroform, methylene
chloride, ethyl acetate, benzene, chlorobenzene, toluene,
n-methylpyrrolidinone, dimethyl sulfoxide, dimethyl formamide or
xylene.
18. A process in accordance to claim 14, wherein the second solvent
is water, methanol, ethanol, propanol, butanol, or acetone.
19. A display device comprised of a first substrate with a
thickness of from about 20 to about 100 microns, containing wax
encapsulated bichromal spheres of from about 45 to about 85 percent
by weight of said substrate, and wherein said first substrate is
situated between a second and third substrate.
20. A device in accordance with claim 19, wherein the second
substrate is a conductive glass or plastic device.
21. A display device in accordance with claim 19, wherein the wax
is a transparent linear hydrocarbon or a branched hydrocarbon each
with from about 18 to about 500 carbon atoms.
22. A display device comprised of a first substrate comprised of a
resin or elastomer and dispersed therein an array of bichromal
spheres encapsulated with a wax, and wherein said first substrate
with said spheres has a thickness of from about 20 to about 100
microns in diameter, and is sandwiched between a second and third
substrate each comprised of a conductive glass or plastic device
each with a thickness of from about 10 to about 500 microns in
diameter.
23. A device in accordance with claim 21, wherein said second and
said third substrate are comprised of a conductive glass or a
plastic.
24. A process in accordance to claim 14, wherein the organic
solvent is hexane, heptane, octane, nonane, decane, dodecane,
Isopar, tetrahydrofuran, diethyl ether, chloroform, methylene
chloride, ethyl acetate, benzene, chlorobenzene, toluene,
n-methylpyrrolidinone, dimethyl sulfoxide, dimethyl formamide or
xylene, and which solvent is selected in an amount of from about 5
to about 40 percent by weight of the bichromal spheres.
25. A process in accordance to claim 14, wherein the second solvent
is water, methanol, ethanol, propanol, butanol, or acetone, and
which solvent is selected in an amount of from about 5 to about 40
percent by weight of the bichromal spheres.
Description
PENDING APPLICATION
[0001] Illustrated in copending application, United States Serial
No. (not yet assigned, D/97443), the disclosure of which is totally
incorporated herein by reference, and which application is being
filed concurrently herewith is a process for the preparation of
bichromal spheres comprising (I) preparing monochromal spheres by
the aggregation and coalescence of an emulsion resin with a first
colorant and an inorganic salt; (ii) contacting the resulting
monchromal spheres with an oxidizing agent, followed by a
polymerization with a vinyl monomer and a free radical initiator;
(iii) forming a of the resulting monochromal spheres on a
substrate; and (iv) subjecting the resulting monochromal spheres to
a vapor thermal deposition with a second colorant dissimilar than
the first colorant to thereby coat one hemisphere of each of said
monochromal spheres and resulting in bichromal spheres with
dissimilar colors.
BACKGROUND OF THE INVENTION
[0002] This invention generally relates to displays, and the
preparation, or fabrication of a display devices, and more
specifically to robust and reflective flexible display devices, and
sheets thereof comprised of small spheres encapsulated with a wax,
for example, wherein small is for example, from about 2 to about
150 microns in volume average diameter as measured by the Coulter
Counter, and more specifically wherein the wax encapsulated sphere
is comprised of a bichromal sphere encapsulated within a
hydrocarbon wax, and wherein the wax encapsulated spheres are
dispersed in an elastomer or plastic membrane with a plastic
conductive coating such as indium tin oxide.
[0003] The displays are useful in generating images, which can be
stored or erased and more specifically the display devices or
devices function by rotating a bichromal sphere by an external
field to create the image.
PRIOR ART
[0004] Electric Paper or twisted ball panel display devices are
known and are described, for example, in U.S. Pat. Nos. 4,126,854;
4,143,103; 4,261,653; 4,438,160; 5,389,945, the disclosures of each
of which are totally incorporated herein by reference, and wherein
the devices are generally comprised of an elastomer, such as a
cured polysiloxane, sandwiched between two ITO coated substrates,
such as glass or MYLAR.TM., and wherein the elastomer layer has
closely packed cavities containing a bichromal sphere suspended in
a dielectric liquid. The image is formed by the application of an
electric field, which rotates the bichromal sphere differentiated
by the different static properties induced by the pigment contained
in the sphere and resulting in contrasting zeta potentials of the
two colored hemispheres of the sphere. It is the difference in zeta
potentials between the hemispheres of the ball which causes the
ball to act like a dipole in the presence of an electrical field,
causing the ball to rotate, until its dipole vector lines up with
the direction of the electrical field established between opposed
electrodes. In addition to the dipole charge distribution found on
the bichromal ball in the presence of an electric field, there is
also a monopole charge which is the net electrical charge of the
entire ball. As a result of the monopole charge, the ball is caused
to move in the direction of the electrical field and will rest and
be retained against a cavity wall. In order for the ball to rotate
easily in the liquid within the cavity, due to the dipole charge,
it is moved from contact with the cavity wall. When at rest against
the cavity wall, friction and other forces will prevent it from
rotating until it has been moved away again, due to the monopole
charge. It is this feature which primarily enables long term, that
is indefinite image retention in the display device if undisturbed
or not handled by force. However, the aforementioned electric paper
devices are not believed to be robust and suffer with respect to
image retention when handled. More specifically, the image formed
on the above prior art displays can deteriorate by touching it,
especially if the user has built up a static charge, by rubbing
over the image, dropping the display device on a surface or by
carrying it. This loss in image retention is caused by the
insufficient lack of adhesion of the bichromal sphere onto the
elastomer, and wherein the spheres detachment from the cavity
surface suspends the bichromal sphere in a low viscosity medium
thus allowing the sphere to rotate uncontrollably within the liquid
cavity. The robust flexible display device of the present
invention, possesses minimum, or substantially no image
deterioration when handled by the user. More specifically, the
display device of the present invention contains a solid wax
encapsulating the bichromal sphere, hence not allowing the for the
sphere to move or minimizing movement within the cavity.
[0005] The fabrication of certain bichromal spheres is known, for
example, the above mentioned 4,143,103 patent, and wherein the
sphere is comprised of black polyethylene with a light reflective
material, for example, titanium oxide, sputtered on hemisphere.
Also in U.S. Pat. No. 4,438,160, the disclosures of which is
totally incorporated herein by reference, a rotary ball is prepared
by coating white glass balls of about 50 microns in diameter, with
an inorganic coloring layer such as MgF.sub.2 or Sb.sub.2S.sub.3 by
evaporation. In a similar process, there is disclosed in an article
entitled "The Gyricon--A twisting Ball Display", published in the
proceedings of the S.I.D., Vol. 18/3 and 4 (1977), a method for
fabricating bichromal balls by first heavily loading chromatic
glass balls with a white pigment such as titanium oxide, followed
by coating from one direction in a vacuum evaporation chamber with
a dense layer of nonconductive black material which coats only one
hemisphere.
[0006] Also in U.S. Pat. No. 4,810,431 by Leidner, there is
disclosed a process for generating spherical particles by (a )
coextruding a fiber of a semi-circular layer of a polyethylene
pigmented white and a black layer of polyethylene containing
magnetite, (b) chopping the resultant fiber into fine particles
ranging from 10 microns to about 10 millimeters, (c) mixing the
particles with clay or anti-agglomeration materials, and (d)
heating the mixture with a liquid at about 120.degree. C. to
spherodize the particles, followed by cooling to allow for
solidification.
[0007] There is also disclosed in U.S. Pat. No. 5,262,809, an
apparatus for fabricating hemispherical bichromal balls, comprising
a separator member having opposing first and second surfaces and an
edge region in contact with both surfaces, and delivery means for
flowing first and second colored hardenable liquid material over
the first and second surfaces, respectively, so that the liquid
materials arrive at the edge at substantially the same flow rate
and form a reservoir outboard of the edge region. The reservoir
comprises side-by-side regions of different colors which do not
intermix. Further means is provided for propelling the first and
second liquid materials away from the separator member and out of
the reservoir into a fluid medium as a plurality of side-by-side
bichromal streams whose forward ends become unstable and break up
into droplets which form into spherical balls, each of the balls
comprising hemispheres of differently colored hardenable liquids.
These bichromal balls are from about 5 to 200 microns in
diameter.
[0008] There is a need for a robust and reflective flexible display
devices which an reimageable multiple times, such as from about 10
to about 10,000 times and preferably from about 100 to about 10,000
times, which displays high reflectivity, such as from about 15 to
about 100 percent or preferably from about 20 to about 50 percent,
which displays high contrast ratios such as from about 3 to about
6, and is robust such that the device can be handled like paper
without image deterioration or image loss.
SUMMARY OF THE INVENTION
[0009] It is an feature of the present invention to provide a
method for the preparation of a robust and flexible electric
papers, gyricon or twisting Ball display devices.
[0010] In another feature of the present invention there is
provided a process for the fabrication of wax encapsulated
bichromal spheres.
[0011] In yet another feature of the present invention there are
provided processes for the preparation of a robust device comprised
of wax encapsulated bichromal spheres, with one hemisphere
displaying a white color, and the other hemisphere displaying a
black color, and wherein each of the bichromal spheres is each of
from about 2 to about 50 microns in diameter, and preferably of
from about 5 to about 25 microns in diameter, and which spheres are
for example, dispersed in an elastomer or plastic coated with a
conductive coating like indium tin oxide.
[0012] Moreover, it is an feature of the present invention to
provide processes for the preparation of wax encapsulated bichromal
spheres by coacervation involving the precipitation of wax onto the
surface of each bichromal sphere.
[0013] In yet another feature of the present invention there is
provided a process for uniformly coating bichromal spheres with a
wax component.
[0014] A further feature of the present invention is to provide a
robust flexible display device with high reflectivity, such as from
about 15 to about 100 percent, and preferably higher than 18
percent, for example from about 20 to about 75 percent.
[0015] Moreover, a further feature of the present invention is to
provide a robust flexible display device with high contrast ratio,
such as from about 3 to about 9.
[0016] Additionally, a further feature of the present invention is
to provide a robust flexible display device which can be handled
like paper without image deterioration or loss.
[0017] The bichromal spheres of the present invention which are
comprised for example, of hemispheres of contrasting, or different
color and dissimilar zeta potentials are useful as a flexible
"electric paper" display device. The present invention is generally
directed to a robust electric paper display device, or a rotary
twisted ball or a Gyricon display device, comprised of bichromal
sphere such as from about 45 to about 65, and more specifically
from about 45 to about 55 percent by weight of the device, in which
one hemispherical, that is about one half, or about 50 percent,
surface of the sphere ball is colored a first color, like white and
the other hemisphere is of a second dissimilar color, that is for
example, a color other than white, such as black, reference for
example U.S. Pat. No. 4,126,854, the disclosure of which is totally
incorporated hereinby reference. The wax encapsulant is for example
a low melting hydrocarbon wax, for example with a melting point of
from about 10 degrees Centigrade to about 80, and more specifically
form about 25 to about 65 degrees Centigrade, and wherein the
carbon chain length or carbon content of the wax is from about 18
to about 1,000, and more specifically from about 100 to about 500
carbon atoms. The flexible display device, when heated to a
temperature above the melting point of the wax, and under the
action of an external electric field, allows the bichromal spheres
to rotate in accordance with their electrical anisotropy to provide
an image. Cooling the device to a temperature at or below about the
melting point of the wax, freezes or immobilizes the image.
[0018] The present invention is also directed to a method for the
preparation of display devices and methods for fabricating the wax
encapsulated bichromal spheres, and wherein each of the spheres are
of small size, such as from about 2 to about 150 microns in
diameter and preferably from about 10 to about 50 microns in
diameter, volume average throughout, and wherein the method
comprises (a) solubilizing a wax in an organic solvent; (b)
suspending bichromal spheres in the organic solvent; (c) adding
thereto a second solvent which precipitates or coacervates the wax
onto each of the bichromal spheres; and (d) optionally, but
preferably isolating the wax encapsulated spheres.
[0019] The bichromal spheres are also preferably fabricated by the
processes as disclosed in copending application D/97443, the
disclosure of which are totally incorporated herein by reference,
or as disclosed in U.S. Pat. No. 4,126,854, the disclosure of which
are totally incorporated herein by reference. Alternatively, other
known methods for the preparation of bichromal spheres can be
practiced such as disclosed in U.S. Pat. No. 5,262,809, the
disclosure of which is totally incorporated herein by
reference.
[0020] With the present invention, there is provided a robust
flexible display device, and wherein the device is comprised of wax
encapsulated bichromal spheres dispersed in an elastomer or
transparent plastic device with a plastic conductive coating. An
image can be formed by heating the display device, or display sheet
in for example, an ionographic apparatus, to a temperature of about
10 to about 20 degrees Centigrade above the melting point of the
wax, causing the wax to melt into a low viscosity liquid, such as a
viscosity of from about 1 to about 100 centipoise, followed by
forming an image with an external electric field or ion deposited
on the display device and casing the bichromal spheres to rotate in
the liquid wax cavity, and followed by removing the image from the
heated device and allowing the wax to solidify on cooling to about
the melting point of the wax or lower and freezing or immobilizing
the bichromal sphere to result in a robust flexible device.
[0021] The wax encapsulated spheres can be prepared by coating the
bichromal spheres with wax as practiced in the art of coacervation.
In an embodiment of the present invention, the wax encapsulated
spheres are prepared by a precipitation technique, for example, by
suspending the bichromal spheres in an organic solvent containing a
dissolved wax component, followed by adding thereto a solvent
within the wax component is insoluble, or substantially insoluble
thereby causing it to precipitate from solution, and wherein, the
wax precipitates and coats onto the bichromal spheres thereby
encapsulating it.
[0022] The process of the present invention in embodiments
comprises the encapsulation of bichromal spheres with a wax
components, followed by dispersing the wax encapsulated bichromal
spheres in an elastomer or plastic device situated on a substrate,
such as MYLAR.TM. coated with indium tin oxide. For example, about
20 to about 25 grams of 70 micron bichromal spheres prepared as
disclosed in U.S. Pat. 5,262,809, the disclosure of which is
totally incorporated herein by reference, is suspended in about 150
to about 200 grams of tetrahydrofuran containing 15 to about 20
grams of Petrolite X-6040 wax (mp=35.degree. C.). To this stirred
mixture is then added about 100 to about 150 grams of methanol
dropwise over a 1 hour period, causing the wax to precipitate and
coat the bichromal spheres. The product is then filtered through a
50 micron screen to result in about 50 to about 55 grams of wax
encapsulated bichromal sphere.
[0023] Illustrative examples of wax components that can be utilized
for encapsulating the bichromal spheres are known, for example
linear and branched hydrocarbons of from about 18 to about 1,000,
and more specifically from about 25 to about 100 carbon atoms, and
with a melting point temperature of from about 15.degree. C. to
about 80.degree. C., and preferably from about 25.degree. C. to
about 60.degree. C., and with molecular weights of from about 300
grams per mole to about 10,000 grams per more as measured by Gel
Permeation Chromatography Preferably. Examples of commercial waxes
are the Petrolite X-series wax, or bees wax. Other useful
encapsulates are low melting hydrocarbons such as Norpar,
Illustrative examples of organic solvents that can be utilized for
dissolving the wax component include nonpopular solvents such as
hexanes, heptanes, octanes, Isopar, Magisol, ether,
tetrahydrofuran, toluene, xylene, ethyl acetate, benzene, naphtha
and the like. Generally organic aromatic solvents and aliphatic
solvents can be selected. Illustrative examples of solvents that
can be utilized for precipitating or coacervating the wax onto the
surface of the bichromal spheres include any solvent for this
purpose, such as water, acetone, and aliphatic alcohols, with for
example, from about 1 to about 25 carbon atoms, such as methanol,
ethanol, propanol, and butanol.
[0024] Illustrative examples of the first substrate utilized for
forming the devices are an epoxy resin, an elastomer such as
polydimethyl siloxane, elastomers such as SYLGARD 184 available
from Dow Corning, a polyurethane, a polyurea, a polyester, and the
like. Examples of the second and third substrate are glass, a
polyester such as MYLARTM, a polyurethane, a polystyene resin, or a
polystyrene-(meth)-acrylate resin with a conductive layer thereon
such as an indium tin oxide coating, and wherein the thickness of
each of the first, second, and third substrates are from about 20
to about 1,000 microns and preferably from about 30 to about 500
micron, and the thickness of the conductive coating is from about
0.5 micron to about 20 micron.
[0025] Aspects of the present invention relate to
[0026] a display comprised of a first component containing spheres
encapsulated within a wax, and thereover and thereunder the first
component substrates;
[0027] a display device comprised of a first substrate containing
an array of bichromal spheres encapsulated with a wax, and wherein
the first substrate is situated between a second substrate and a
third substrate;
[0028] a display device wherein the first substrate is an elastomer
or a plastic;
[0029] a display device wherein the second substrate is an indium
tin oxide coated glass or a polyester of
polyethylene-terephthalate;
[0030] a display wherein the second substrate is indinium tin
oxide;
[0031] a display device wherein the bichromal sphere is from about
5 to about 25 microns in diameter, and is comprised of one
hemisphere colored white, and the remaining hemisphere coated with
a color other than white;
[0032] a display wherein the other that white is black, blue, red,
yellow, cyan, green, magenta, orange, green, or mixtures
thereof;
[0033] a display device wherein the bichromal sphere is
encapsulated in a wax comprised of a hydrocarbon.
[0034] a display device wherein the wax is a transparent linear
hydrocarbon or a branched hydrocarbon each with from about 18 to
about 1,000 carbon atoms;
[0035] a display device wherein the first substrate is an elastomer
of polydimethylsiloxane or a polyurethane;
[0036] a display device wherein the first substrate is a plastic of
an epoxy resin, a polyester resin, a polyamide resin, a
polystyrene-(meth)acrylate resin, a polydimthylsiloxane, or a
polyurethane;
[0037] a display device wherein the second and third substrate is a
conductive glass;
[0038] a display device wherein the second substrate is a
conductive plastic of a polyester resin coated with indinium tin
oxide;
[0039] a process for the preparation of wax encapsulated bichromal
spheres comprising (a) solubilizing a wax in an organic solvent;
(b) suspending bichromal spheres in the organic solvent; (c) adding
thereto a second solvent which precipitates or coacervates the wax
onto each of the bichromal spheres; and (d) optionally isolating
the wax encapsulated spheres;
[0040] a process wherein the wax is a linear or branched
hydrocarbon with about 18 to about 1,000 carbon atoms;
[0041] a process wherein the wax has a melting point of from about
15 degrees Centigrade to about 80 degrees Centigrade;
[0042] a process wherein the organic solvent is hexane, heptane,
octane, nonane, decane, dodecane, Isopar, tetrahydrofuran, diethyl
ether, chloroform, methylene chloride, ethyl acetate, benzene,
chlorobenzene, toluene, n-methylpyrrolidinone, dimethyl sulfoxide,
dimethyl formamide or xylene;
[0043] a process wherein the second solvent is water, methanol,
ethanol, propanol, butanol, or acetone;
[0044] a display device comprised of a first substrate with a
thickness of from about 20 to about 100 microns, containing wax
encapsulated bichromal spheres of from about 45 to about 85 percent
by weight of the substrate, wherein the first substrate is situated
between a second and third substrate;
[0045] a display device comprised of a first substrate comprised of
a resin or elastomer and dispersed therein an array of bichromal
spheres encapsulated with a wax, and wherein the first substrate
with said spheres has a thickness of from about 20 to about 100
microns, and is sandwiched between a second and third substrate
comprised of a conductive glass or plastic device each with a
thickness of from about 10 to about 500 microns in diameter;
[0046] a device wherein said second and said third substrate are
comprised of a conductive glass or plastic device;
[0047] a process wherein the organic solvent is hexane, heptane,
octane, nonane, decane, dodecane, Isopar, tetrahydrofuran, diethyl
ether, chloroform, methylene chloride, ethyl acetate, benzene,
chlorobenzene, toluene, n-methylpyrrolidinone, dimethyl sulfoxide,
dimethyl formamide or xylene, and which solvent is selected in an
amount of from about 5 to about 40 percent by weight of the
bichromal spheres; and
[0048] a process wherein the second solvent is water, methanol,
ethanol, propanol, butanol, or acetone, and which solvent is
selected in an amount of from about 5 to about 40 percent by weight
of the bichromal spheres.
[0049] The following EXAMPLES are provided:
EXAMPLE 1
[0050] Preparation of a robust and reflective display device
comprised of 70 volume average micron bichromal spheres
encapsulated within 25% by weight of hydrocarbon wax (Petrolite
X-6040), dispersed in a siloxane elastomer and sandwiched between
two indinium tin oxide-(ITO) coated glass or MYLAR.TM. substrates
was accomplished as follows:
[0051] Step 1. Preparation of 70 Micron Bichromal Spheres
Encapsulated with 25% by Weight of Wax (Petrolite X-6040):
[0052] A 1 liter beaker equipped with a mechanical stirrer was
charged with 220 grams of tetrahydrofuran solvent, 75 grams of 70
micron black and white colored bichromal spheres (prepared as
disclosed in U.S. Pat. No. 5,262,809, the disclosure of which is
totally incorporated herein by reference) and 18.75 grams of
Petrolite X-6040 wax (mp=35.degree. C.). To this stirred mixture
was then added about 125 grams of methanol dropwise over a 3 hour
period, causing the wax to precipitate and fully coat each of the
bichromal spheres. The product was then filtered through a 50
micron screen to result in about 85 grams of wax encapsulated black
and white colored bichromal spheres.
[0053] Step 2. Preparation of the Display Device
[0054] A display device was fabricated from the above prepared
spheres by (1) mixing 50 grams of the prepared bichromal spheres
with 50 grams of SYIGARD.RTM. 185 silicone elastomer Kit available
from Dow Corning; (2) forming a device by spreading the resulting
mixture on a glass plate surface and which spreading was with a
metering bar such as an 8-Path Wet Film Applicator (available from
P. Gardner Company) with a gap of from about 20 microns to about
500 microns, and crosslinking the SYLGARD elastomer device by
heating to a temperature of from about 80.degree. C. to about
100.degree. C. for a duration of from about 3 to about 24 hours;
and then (3) sealing the device between addressing plates of indium
tin oxide coated glass or preferably MYLAR.TM., each with a
thickness of from about 20 to about 500 microns.
EXAMPLE 2
[0055] Preparation of a robust and reflective display device
comprised of 70 micron Bichromal spheres encapsulated within 20% by
weight of hydrocarbon wax (Petrolite X-6040), dispersed in a
siloxane elastomer and sandwiched between two MYLAR.TM. substrates
was accomplished as follows
[0056] Step 1. Preparation of 70 Micron Bichromal Spheres
Encapsulated with 20 Percent by Weight of Wax (Petrolite
X-6040):
[0057] A 1 liter beaker equipped with a mechanical stirrer was
charged with 220 grams of tetrahydrofuran solvent, 75 grams of 70
micron black and white colored bichromal spheres (prepared as
disclosed in U.S. Pat. 5,262,809) and 15 grams of Petrolite X-6040
wax (mp=35.degree. C.). To this stirred mixture was then added
about 125 grams of methanol dropwise over a 3 hour period, causing
the wax to precipitate and fully coat the bichromal spheres. The
product was then filtered through a 50 micron screen to result in
about 83 grams of wax encapsulated bichromal spheres.
[0058] Step 2. Preparation of the Display Device
[0059] A display device was fabricated from the above bichromal
spheres by (1) mixing 50 grams of the prepared bichromal spheres
with 50 grams of SYIGARD.RTM. 185 silicone elastomer Kit available
from Dow Corning; (2) forming a device by spreading the mixture on
a glass plate surface and which spreading was with a metering bar
such as an 8-Path Wet Film Applicator (available from P. Gardner
Company) with a gap of from about 20 microns to about 500 microns,
and crosslinking the SYLGARD elastomer device by heating to a
temperature of from about 80.degree. C. to about 100.degree. C. for
a duration of from about 3 to about 24 hours; and (3) then sealing
the device between addressing plates of indium tin oxide, coated
glass or MYLAR.TM., each with a thickness of from about 20 to about
500 microns in diameter.
EXAMPLE 3
[0060] Preparation of a robust and reflective display device
comprised of 70 micron Bichromal spheres encapsulated within 25% by
weight of hydrocarbon wax (Petrolite), dispersed in a siloxane
elastomer and sandwiched between two substrates was accomplished as
follows
[0061] Step 1. Preparation of 70 Micron Bichromal Spheres
Encapsulated with 25% by Weight of Wax (Petrolite X-6028):
[0062] A 1 liter beaker equipped with a mechanical stirrer was
charged with 220 grams of tetrahydrofuran solvent, 25 grams of 70
micron of black and white colored bichromal spheres (prepared as
disclosed in U.S. Pat. No. 5,262,809) and 18 grams of Petrolite
(X-6028) wax (mp=41.degree. C.). To this stirred mixture was then
added about 125 grams of methanol dropwise over a 3 hour period,
causing the wax to precipitate and fully coat each of the bichromal
spheres. The product was then filtered through a 50 micron screen
to result in about 85 grams of wax encapsulated bichromal
spheres.
[0063] Step 2. Preparation of the Display Devices.
[0064] A display device was fabricated from the above bichromal
sphere by (1) mixing 50 grams of the prepared bichromal spheres
with 50 grams of SYIGARD.RTM. 185 silicone elastomer Kit available
from Dow Corning; (2) forming a device by spreading the mixture on
a glass plate surface and which spreading was with a metering bar
such as an 8-Path Wet Film Applicator (available from P. Gardner
Company) with a gap of from about 20 microns to about 500 microns,
and crosslinking the SYLGARD elastomer device by heating to a
temperature of from about 80.degree. C. to about 100.degree. C. for
a duration of from about 3 to about 24 hours; and (3) then sealing
device between addressing plates of Indium tin oxide coated glass
or MYLAR.TM., each with a thickness of from about 20 to about 500
microns in diameter.
[0065] Other modifications of the present invention may occur to
one of ordinary skill in the art subsequent to a review of the
present application, and these modifications, including
equivalents, or substantial equivalents thereof, are intended to be
included within the scope of the present invention.
* * * * *