US3813549A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-healing electrode for uniform negative corona
Assignee: International Business Machines Corp
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Filing: 1972-12-26
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Granted: 1974-05-28
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Expires: 1992-12-26
Abstract
Abstract The present invention relates to electrodes used for charging electrophotographic image surfaces in copying machines. More particularly, the disclosure is directed to the negative corona discharge electrodes which produce a negative charge that is applied to the photoconductive surface exposed to the corona discharge. In the present invention, the electrode structure includes a combination of a wire of valve metal with a high resistivity coating spread uniformly over the surface of the wire. The valve metal, one example being tantalum, may serve as the electrode wire itself or may surround an inner wire such as stainless steel. By providing an electrode for corona discharge having a uniform high resistive coating, the plasma glow produced will spread uniformly along the length of the wire. By using a valve metal, which forms a hard oxide under the high resistivity coating, the electrode is self-healing in that if cracks or imperfections occur in the coating, the exposed valve metal will oxidize and fill in the cracks and imperfections.
Inventors
- 👤 Stefano T Di
- 👤 R Laibowitz
- 👤 R Rosenberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:31
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/02; G03G15/0291; H; H05; H05F; H05F3/00; H05F3/04
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
48 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of the oxide of said valve metal wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
Claim 2
Dependent Claim
48 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of the oxide of said valve metal wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
Claim 3
Dependent Claim
26 words
An electrode means according to claim 1 wherein said valve metal is tantalum and said high resistivity material of said outer coating comprises anodized tantalum oxide.
Claim 4
Dependent Claim
18 words
An electrode means according to claim 1 wherein said valve metal surrounds a high tensile strength core wire.
Claim 5
Dependent Claim
30 words
An electrode means according to claim 1 wherein said electrode means is adapted to connect to a potential source to produce a negative corona discharge for use in electrographic imaging.
Claim 6
Dependent Claim
18 words
An electrode means according to claim 1, wherein said outer coating comprises a film about 1,000 Angstroms thick.
Claim 7
Dependent Claim
69 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of high resistivity material, said outer coating being selected from the group consisting of an oxide of said valve metal, silicon nitride, silicon dioxide and an insulating polymer, wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
Claim 8
Dependent Claim
69 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of high resistivity material, said outer coating being selected from the group consisting of an oxide of said valve metal, silicon nitride, silicon dioxide and an insulating polymer, wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
Claim 9
Dependent Claim
42 words
An electrode means according to claim 6 wherein said inner core metal is tantalum and said uniform coating of high resistivity material is an amorphous semi-insulating coating selected from the group consisting of silicon nitride Si3N4, silicon dioxide SiO2, and insulating polymers.
Claim 10
Dependent Claim
44 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of tantalum surrounded by an outer uniform coating of the oxide of tantalum wherein said tantalum of said outer coating comprises an anodized tantalum oxide film about 1,000 Angstroms thick.
Claim 11
Dependent Claim
44 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of tantalum surrounded by an outer uniform coating of the oxide of tantalum wherein said tantalum of said outer coating comprises an anodized tantalum oxide film about 1,000 Angstroms thick.
Claim 12
Dependent Claim
64 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of high resistivity material, said outer coating being selected from the group consisting of a silicon nitride, silicon dioxide and an insulating polymer, wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
Claim 13
Dependent Claim
64 words
An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of high resistivity material, said outer coating being selected from the group consisting of a silicon nitride, silicon dioxide and an insulating polymer, wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |