Patent US2164441A successfully refreshed from Google Patents.
US3677751A
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Polarity reversal electrophotography
Assignee: Ricoh Co Ltd
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Filing: 1969-11-14
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Granted: 1972-07-18
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Expires: 1989-11-14
Abstract
Abstract D R A W I N G AN ELECTROPHOTOGRAPHY METHOD WHEREIN A PHOTOSENSITIVE LAYER IS CHARGED UP IN THE DARK, THE PHOTOSENSITIVE LAYER BEING OVERCOATED BY AN INSULATOR LAYER, AND A CHARGE OF THE POLARITY OPPOSITE TO THAT OF THE INITIAL CHARGE IS APPLIED ON THE INSULATOR LAYER IN A QUANTITU LESS THAN THAT OF THE INITIAL CHARGE, AND THEREAFTER, THE ELECTRIC POLARITY AT THE SPOTS CORRESPONDING TO THE LIGHT AND DARK SPOTS OF AN ORIGINAL IS REVERSED BY AN IMAGE LIGHT PROJECTION.
Inventors
- 👤 Wasaburo Ohta
- 👤 Katsuo Sakai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:47
CPC Classifications
G; G03; G03G; G03G13/00; G03G13/04; G03G15/00; G03G15/22; G03G15/226; Y; Y10; Y10S; Y10S430/00; Y10S430/001; Y10S430/102
Claims Analysis
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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) | 1975-07-18 | 1976-01-17 | 1976-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-18 | 1980-01-17 | 1980-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-18 | 1984-01-17 | 1984-07-18 | $7700.00 | Window Closed / Lapsed |