Patent US3942888A successfully refreshed from Google Patents.
US3942888A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stepped transfer roller
Assignee: Xerox Corp
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Filing: 1975-02-06
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Granted: 1976-03-09
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Expires: 1995-02-06
Abstract
Abstract A biased roller electrostatographic image transfer system in which the diameter of a resilient bias transfer roll is slightly larger at its outer end areas in comparison to its central copy sheet engaging area, so that the majority of the roll loading pressure is absorbed by these larger diameter end steps, which roll directly against the imaging surface outside of the copy area, and so that a relatively lower roll pressure is provided against the copy sheet in the operating nip. This reduction in the mechanical pressure in the transfer nip can provide lower "hollow character" transfer defects, yet allows a sufficiently high roller loading force to prevent roll bounce and vibration.
Inventors
- 👤 John Maksymiak
- 👤 Daniel S. Hoffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:26
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/14; G03G15/16; G03G15/1665; G03G15/167; G03G15/1685
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
218 words
In an electrostatographic copying system wherein an image is transferable from image support surface means to copy sheets of a predetermined range of thickness and a predetermined maximum lateral dimension, wherein a transfer roller forms a transfer nip with said image support means for passage of said copy sheets through said nip against said image support means for said image transfer, and wherein pressure means are provided for pressing said transfer roller against said image support means with a preset total force, the improvement wherein: said transfer roller has a substantially cylindrical and resiliently deformable integral exterior surface with a central portion and two integral end portions at each end of said central portion, said central portion has a first diameter and extends in length along said roller further than said predetermined maximum lateral dimension of said copy sheets, said end portions have a second diameter slightly greater than said first diameter of said central portion, said end portions directly deformably rollably engage said image support means with a force from said pressure means which is a substantial portion of said total force, and said force on said end portions producing a first pressure, and said central portion rollably engages said copy sheets in said nip with a second pressure which is substantially lower than said first pressure.
Claim 2
Dependent Claim
218 words
In an electrostatographic copying system wherein an image is transferable from image support surface means to copy sheets of a predetermined range of thickness and a predetermined maximum lateral dimension, wherein a transfer roller forms a transfer nip with said image support means for passage of said copy sheets through said nip against said image support means for said image transfer, and wherein pressure means are provided for pressing said transfer roller against said image support means with a preset total force, the improvement wherein: said transfer roller has a substantially cylindrical and resiliently deformable integral exterior surface with a central portion and two integral end portions at each end of said central portion, said central portion has a first diameter and extends in length along said roller further than said predetermined maximum lateral dimension of said copy sheets, said end portions have a second diameter slightly greater than said first diameter of said central portion, said end portions directly deformably rollably engage said image support means with a force from said pressure means which is a substantial portion of said total force, and said force on said end portions producing a first pressure, and said central portion rollably engages said copy sheets in said nip with a second pressure which is substantially lower than said first pressure.
Claim 3
Dependent Claim
36 words
The copy system of claim 1, wherein said force of both said end portions against said image support means is more than one-half of said total force applied by said pressure means to said transfer roller.
Claim 4
Dependent Claim
28 words
The copying system of claim 1, wherein said central portion is substantially less deformed in said nip than said end portions are deformed against said image support means.
Claim 5
Dependent Claim
21 words
The copying system of claim 1, wherein said roller has a homogenious layer of resilient material providing said integral exterior surface.
Claim 6
Dependent Claim
22 words
The copying system of claim 4, wherein said layer of resilient material is electrically relaxable and electrically biased for said image transfer.
Claim 7
Dependent Claim
28 words
The copying system of claim 2, wherein said central portion is substantially less deformed in said nip than said end portions are deformed against said image support means.
Claim 8
Dependent Claim
28 words
The copying system of claim 4, wherein said central portion is substantially less deformed in said nip than said end portions are deformed against said image support means.
Claim 9
Dependent Claim
35 words
The copying system of claim 1, wherein said central portion presses against said copy sheets in said nip with a nip force which is substantially less than said total force applied by said pressure means.
Claim 10
Dependent Claim
45 words
The copying system of claim 8, wherein said nip force is less than one-half, and wherein said force of both said end portions against said image support means is more than one-half, of said total force applied by said pressure means to said transfer roller.
Claim 11
Dependent Claim
17 words
The copying system of claim 1, wherein said end portions are cylindrical steps from said central portion.
Claim 12
Dependent Claim
37 words
The copying system of claim 1, wherein said end portions are adapted to hold said central portion spaced from said image support means by a distance less than said predetermined range of thicknesses of said copy sheets.
References Cited (Backward Citations)
US2807233A
Cited
US3627523A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |