US4905051A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fixing means for electrophotographic copier
Assignee: Sharp Corp
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Filing: 1988-09-23
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Granted: 1990-02-27
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Expires: 2008-09-23
Abstract
Abstract A fixing means for an electrophotographic copier includes a first roller and a second roller which are compressed against each other and serve to fix toner images on an image transferring medium passed therebetween. A control means is programmed to operate the rollers such that the heating of the second roller is continued for a predetermined length of time or until the surface temperature of the second roller reaches a certain predetermined temperature level after the surface temperature of the first roller reaches another predetermined temperature level such that the second roller is prevented from cooling down suddenly after the fixing operation is started. In another aspect of the present invention, the size of the image transferring medium passed between the rollers is detected and the heaters for the rollers are controlled accordingly such that temperature variations on the roller surfaces can be reduced and hence the roller lifetimes can be improved.
Inventors
- 👤 Fumio Satoh
- 👤 Yoichi Shimazawa
- 👤 Yasuhiro Takai
- 👤 Katsumi Nakanishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:20
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/20; G03G15/2003; G03G15/2014; G03G15/2039; G03G15/2042
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
220 words
A fixing means for a copier comprising a first roller, a second roller adapted to become compressed against said first roller and to thereby receive heat from said first roller, said first roller and said second roller serving to fix toner images on an image transferring medium, means for measuring surface temperatures of said first and second rollers, heating means for independently heating said first roller and said second roller, and a control means programmed to initially operate said heating means to heat both said first and second rollers until a first point in time when the surface temperature of said first roller reaches a first predetermined temperature level which is appropriate for fixing, to begin to rotate said rollers and stop heating said second roller by said heating means at said first point in time, to thereafter continue to rotate said rollers while continuing to heat said first roller by said heating means until a second point in time when the surface temperature of said first roller reaches a second predetermined temperature level which is higher than said first temperature level, and to thereafter alternately stop and start heating said first roller by said heating means such that the surface temperature of said first roller stays substantially at said second predetermined temperature level after said second point in time.
Claim 2
Dependent Claim
220 words
A fixing means for a copier comprising a first roller, a second roller adapted to become compressed against said first roller and to thereby receive heat from said first roller, said first roller and said second roller serving to fix toner images on an image transferring medium, means for measuring surface temperatures of said first and second rollers, heating means for independently heating said first roller and said second roller, and a control means programmed to initially operate said heating means to heat both said first and second rollers until a first point in time when the surface temperature of said first roller reaches a first predetermined temperature level which is appropriate for fixing, to begin to rotate said rollers and stop heating said second roller by said heating means at said first point in time, to thereafter continue to rotate said rollers while continuing to heat said first roller by said heating means until a second point in time when the surface temperature of said first roller reaches a second predetermined temperature level which is higher than said first temperature level, and to thereafter alternately stop and start heating said first roller by said heating means such that the surface temperature of said first roller stays substantially at said second predetermined temperature level after said second point in time.
Claim 3
Dependent Claim
42 words
The fixing means of claim 1 wherein said control means includes a central processing unit which serves to cause said rollers to rotate for a predetermined length of time after the surface temperature of said first roller reaches said predetermined temperature level.
Claim 4
Dependent Claim
27 words
The fixing means of claim 2 wherein said control means further includes a memory means which serves to store a value indicative of said length of time.
Claim 5
Dependent Claim
258 words
A fixing means for a copier comprising a first roller, a second roller adapted to become compressed against said first roller, means for measuring surface temperatures of said first and second rollers, heating means for independently heating said first roller and said second roller, said first roller and said second roller being adapted to be heated by said heating means to serve to fix toner images on an image transferring medium, and a control means for controlling the surface temperatures of said rollers and preventing a sudden drop of surface temperature of said first roller, said control means being programmed to first operate said heating means to heat both said first and second rollers until a first point in time when the surface temperature of said first roller reaches a first predetermined temperature level, to begin to rotate said rollers and stop heating said second roller by said heating means at said first point in time, to thereafter continue to rotate said rollers while continuing to heat said first roller by said heating means until a second point in time when the surface temperature of said first roller reaches a second predetermined temperature level higher than said first predetermined temperature level, to thereafter stop and start heating said first roller by said heating means such that the surface temperature of said first roller stays substantially at said second predetermined temperature level after said second point in time, and to thereafter stop rotating said rollers when the surface temperature of said second roller reaches a third predetermined temperature level.
Claim 6
Dependent Claim
258 words
A fixing means for a copier comprising a first roller, a second roller adapted to become compressed against said first roller, means for measuring surface temperatures of said first and second rollers, heating means for independently heating said first roller and said second roller, said first roller and said second roller being adapted to be heated by said heating means to serve to fix toner images on an image transferring medium, and a control means for controlling the surface temperatures of said rollers and preventing a sudden drop of surface temperature of said first roller, said control means being programmed to first operate said heating means to heat both said first and second rollers until a first point in time when the surface temperature of said first roller reaches a first predetermined temperature level, to begin to rotate said rollers and stop heating said second roller by said heating means at said first point in time, to thereafter continue to rotate said rollers while continuing to heat said first roller by said heating means until a second point in time when the surface temperature of said first roller reaches a second predetermined temperature level higher than said first predetermined temperature level, to thereafter stop and start heating said first roller by said heating means such that the surface temperature of said first roller stays substantially at said second predetermined temperature level after said second point in time, and to thereafter stop rotating said rollers when the surface temperature of said second roller reaches a third predetermined temperature level.
Claim 7
Dependent Claim
28 words
The fixing means of claim 4 wherein said control means includes a memory means which serves to store values indicative of said first and second predetermined temperature levels.
Claim 8
Dependent Claim
29 words
The fixing means of claim 4 wherein said control means includes a central processing unit which serves to compare surface temperatures of said rollers with said predetermined temperature levels.
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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) | 1993-02-26 | 1993-08-28 | 1994-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-26 | 1997-08-28 | 1998-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-26 | 2001-08-28 | 2002-02-27 | $7700.00 | Window Closed / Lapsed |