Patent US4652114A successfully refreshed from Google Patents.
US4652114A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrophotographic copying apparatus and process
Assignee: 3M Co
•
Filing: 1986-06-02
•
Granted: 1987-03-24
•
Expires: 2006-06-02
Abstract
Abstract An electrophotographic copying apparatus includes a copying cycle which always alternates development between two image areas to equalize wear along the length of its photosensitive belt and which eliminates a cleaning cycle after the final copy of a copying cycle to reduce belt revolutions. Also included is a combined charger/precleaner to reduce size and a light image mask to prevent unnecessary toning of the belt.
Inventors
- 👤 James F. Sobieski
- 👤 Robert A. Muehlhausen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:40
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/50; G03G15/06; G03G15/08; G03G15/09; G03G15/22; G03G15/221; G03G15/223; G03G15/26; G03G15/263; G03G21/00; G03G21/0005; G03G21/0047; G03G2221/00; G03G2221/0005
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
71 words
An electrophotographic copying apparatus including a photosensitive element and a development station, comprising: a combined charging/precleaning corona unit which may be selectively activated to impart an electrical charge of a given polarity and potential to said photosensitive element prior to development and an electrical charge of said given polarity, but at a reduced potential, subsequent to development; and switch means for selectively activating said combined corona unit and changing said potential.
Claim 2
Dependent Claim
71 words
An electrophotographic copying apparatus including a photosensitive element and a development station, comprising: a combined charging/precleaning corona unit which may be selectively activated to impart an electrical charge of a given polarity and potential to said photosensitive element prior to development and an electrical charge of said given polarity, but at a reduced potential, subsequent to development; and switch means for selectively activating said combined corona unit and changing said potential.
Claim 3
Dependent Claim
72 words
An electrophotographic copying apparatus according to claim 1 wherein said combined charging/precleaning corona unit is of the scorotron type in that said corona unit includes at least one corona wire and a grid disposed between said corona wire and said photosensitive element, wherein said charge potential is changed by changing an electrical bias applied to said grid, and wherein said switch means comprises means for changing said bias applied to said grid.
Claim 4
Dependent Claim
24 words
An electrophotographic copying apparatus according to claim 2 wherein said means for changing said bias includes a power supply selectively connected to said grid.
Claim 5
Dependent Claim
40 words
An electrophotographic copying apparatus according to claim 2 wherein said means for changing said bias includes an electrical circuit between said grid and ground potential and at least one Zener diode which may be selectively inserted into said electrical circuit.
Claim 6
Dependent Claim
110 words
An electrophotographic copying apparatus including an endless photosensitive element, a development station and a cleaning station, comprising: a single, combined charging/precleaning corona unit means for performing all charging functions associated with development and cleaning of said photosensitive element, said combined corona unit means selectively operating to impart an electrical charge of a given polarity and potential to said photosensitive element prior to development in one mode and an electrical charge of said given polarity, but at a reduced potential, prior to cleaning in another mode; and means for selectively operating said combined corona unit means in one or the other of said modes during operation of said electrophotographic copying apparatus.
Claim 7
Dependent Claim
110 words
An electrophotographic copying apparatus including an endless photosensitive element, a development station and a cleaning station, comprising: a single, combined charging/precleaning corona unit means for performing all charging functions associated with development and cleaning of said photosensitive element, said combined corona unit means selectively operating to impart an electrical charge of a given polarity and potential to said photosensitive element prior to development in one mode and an electrical charge of said given polarity, but at a reduced potential, prior to cleaning in another mode; and means for selectively operating said combined corona unit means in one or the other of said modes during operation of said electrophotographic copying apparatus.
References Cited (Backward Citations)
US3649262A
Cited
US3838921A
Cited
US3647293A
Cited
US3647293B1
Cited
US3637306A
Cited
US4017170A
Cited
US4017170B1
Cited
US4240723A
Cited
US4087170A
Cited
US4129072A
Cited
US4432631A
Cited
US4200387A
Cited
US4233286A
Cited
US4335420A
Cited
US4311780A
Cited
US4320958A
Cited
US4465360A
Cited
US4372669A
Cited
US4456365A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-23 | 1990-09-22 | 1991-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-23 | 1994-09-22 | 1995-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-23 | 1998-09-22 | 1999-03-24 | $7700.00 | Window Closed / Lapsed |