US4298448A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrophoretic display
Assignee: BBC BROWN BOVERI and COMPANY Ltd
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Filing: 1980-01-24
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Granted: 1981-11-03
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Expires: 2000-01-24
Abstract
Abstract An electrophoretic display including a cell having two plates spaced apart and provided at least regionally with electrodes, where at least one plate and an associated electrode facing the observer are transparent. The cell contains a suspension consisting of an inert dielectric liquid phase and a dispersed solid phase which at least in part are optically discriminable electrophoretic particles. The individual electrophoretic particles each are of practically the same density as the liquid phase, and at least part of the electrophoretic particles are pigment particles provided with a coating of organic material which is solid at the cell operating temperature but which melts at higher temperatures. The coating material contains at least one charge control agent. The charge control agent, preferably a salt of a divalent metal or metal of higher valency and of an organic acid, imparts a well-defined, uniform surface charge and a well defined, uniform surface potential to the particles.
Inventors
- 👤 Klaus Muller
- 👤 Andreas Zimmermann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:51
CPC Classifications
G; G03; G03G; G03G17/00; G03G17/04; G02; G02F; G02F1/00; G02F1/01; G02F1/165; G02F1/166; G02F1/167
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
144 words
An electrophoretic display comprising: a cell having two opposed plates spaced relative to each other and at least regionally provided with electrodes of which at least the plate facing an observer and its electrode are transparent, said cell containing a suspension consisting of an inert continuous dielectric liquid phase and a dispersed solid phase constituted at least in part by optically discriminable electrophoretic particles, said individual electrophoretic particles all having practically the same density as the liquid phase, and at least part of the electrophoretic particles constituted by pigment particles coated with a sheath of organic material solidified at the cell operating temperature but melting at higher temperatures, wherein the sheath matrial contains at least one charge control agent so as to impart a well-defined and practically uniform surface charge as well as a well-defined and practically uniform surface potential to the electrophoretic particles.
Claim 2
Dependent Claim
144 words
An electrophoretic display comprising: a cell having two opposed plates spaced relative to each other and at least regionally provided with electrodes of which at least the plate facing an observer and its electrode are transparent, said cell containing a suspension consisting of an inert continuous dielectric liquid phase and a dispersed solid phase constituted at least in part by optically discriminable electrophoretic particles, said individual electrophoretic particles all having practically the same density as the liquid phase, and at least part of the electrophoretic particles constituted by pigment particles coated with a sheath of organic material solidified at the cell operating temperature but melting at higher temperatures, wherein the sheath matrial contains at least one charge control agent so as to impart a well-defined and practically uniform surface charge as well as a well-defined and practically uniform surface potential to the electrophoretic particles.
Claim 3
Dependent Claim
37 words
A display as claimed in claim 1 wherein the charge control agent comprises: a compound selected from the group consisting of a salt and a complex compound of an at least divalent metal and an organic acid.
Claim 4
Dependent Claim
30 words
A display as claimed in claims 1 or 2 where the charge control agent is contained in the coating material at least partly in the form of a solid solution.
Claim 5
Dependent Claim
16 words
A display as claimed in claim 2 where the organic acid contains at least 5 C-atoms.
Claim 6
Dependent Claim
15 words
A display as claimed in claim 4 where the organic acid is a carboxylic acid.
Claim 7
Dependent Claim
20 words
A display as claimed in claim 5 where the carboxylic acid is a monobasic acid with at least 8 C-atoms.
Claim 8
Dependent Claim
17 words
A display as claimed in claim 6 where the organic acid is an alkanoic or alkenoic acid.
Claim 9
Dependent Claim
16 words
A display as claimed in claim 7 where the organic acid is a high fatty acid.
Claim 10
Dependent Claim
16 words
A display as claimed in claim 5 where the organic acid is an alicyclic carboxylic acid.
Claim 11
Dependent Claim
29 words
A display as claimed in claim 2 where the at least divalent metal is selected from groups IIA, IIIA, or the iron metal group, or where it is Cu(II).
Claim 12
Dependent Claim
31 words
A display as claimed in claims 1 or 2 where the organic coating material is a material soluble in the range between 50° and 150° C. in practically nonpolar aprotic solvents.
Claim 13
Dependent Claim
21 words
A display as claimed in claims 1 or 2 where the coating material at least in part consists of a wax.
Claim 14
Dependent Claim
14 words
A display according to claim 5, wherein the organic acid is a monocarboxylic acid.
Claim 15
Dependent Claim
19 words
A display according to claim 5, wherein said carboxylic acid is a monobasic acid with at least 12 C-atoms.
Claim 16
Dependent Claim
27 words
A display according to claim 7 wherein said organic acid is a high fatty acid selected from the group consisting of a stearic acid or oleic acid.
Claim 17
Dependent Claim
14 words
A display according to claim 9 wherein said alicyclic acid consists of naphtheic acid.
Claim 18
Dependent Claim
26 words
A display according to claim 12 wherein said wax comprises: a paraffinic wax which melts at a temperature in the range between 50° and 200° C.
Claim 19
Dependent Claim
22 words
A display according to claim 17 wherein said paraffinic wax has a melting temperature in the range between 50° and 100° C.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-02 | 1985-05-04 | 1985-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-02 | 1989-05-04 | 1989-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-02 | 1993-05-04 | 1993-11-03 | $7700.00 | Window Closed / Lapsed |