Patent US3804516A successfully refreshed from Google Patents.
US3804516A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fire detecting device for a photographic printing machine
Assignee: Xerox Corp
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Filing: 1972-12-11
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Granted: 1974-04-16
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Expires: 1992-12-11
Abstract
Abstract A device in which the presence of a burning article on a moving conveyor is detected for preventing the spread of a fire therefrom. The device has at least one temperature sensitive resistance element along the conveyor path which leads from the fusing area of an electrophotographic printing machine for measuring any variation in the temperature along the path produced by a burning sheet. The resistance element is part of an electrical circuit which will generate an ouput signal in response to any variation in the temperature caused by a sheet to warn an operator of a fire in the machine. The foregoing abstract is neither intended to define the invention disclosed in the specification nor is it intended to be limiting as to the scope of the invention in any way.
Inventors
- 👤 Mott J De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:05
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/20; G03G15/2003; G03G15/2007; G08; G08B; G08B17/00; G08B17/06
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
115 words
A device for indicating the presence of a burning article on a moving conveyor system, including: a first resistance element adjacent the conveyor system, said resistance element having a variable effective resistance dependent upon thermal conditions in the region thereof; means responsive to a variation in the resistance of said first resistance element for generating an output signal indicative of the presence of the burning article on the moving conveyor system; bridge circuit means having associated therewith said first resistance element and a second resistance element spaced from said first resistance element to compensate for normal thermal variations in the environment; and means for generating a substantially constant current to energize said bridge circuit means.
Claim 2
Independent Claim
115 words
A device for indicating the presence of a burning article on a moving conveyor system, including: a first resistance element adjacent the conveyor system, said resistance element having a variable effective resistance dependent upon thermal conditions in the region thereof; means responsive to a variation in the resistance of said first resistance element for generating an output signal indicative of the presence of the burning article on the moving conveyor system; bridge circuit means having associated therewith said first resistance element and a second resistance element spaced from said first resistance element to compensate for normal thermal variations in the environment; and means for generating a substantially constant current to energize said bridge circuit means.
Claim 3
Dependent Claim
35 words
A device as recited in claim 1, further including means, responsive to said signal generating means, for displaying the output signal to alert an operator that a burning article is disposed on the conveyor system.
Claim 4
Dependent Claim
46 words
A device as recited in claim 1, wherein said signal generating means includes a voltage comparator arranged to provide a digital output corresponding to the variation in resistance of said first resistance element to indicate the presence of the burning article on the moving conveyor system.
Claim 5
Dependent Claim
20 words
A device as recited in claim 3, wherein said first resistance element is preferably made from an elongated tungsten wire.
Claim 6
Dependent Claim
154 words
An electrophotographic printing machine of the type having a conveyor system arranged to move a sheet of support material having a toner powder image adhering substantially permanently thereon from a fusing apparatus adapted to heat and coalesce the toner powder image to the sheet of support material, wherein the improvement includes: a first resistance element adjacent the conveyor system, said resistance element having a variable effective resistance dependent upon thermal conditions in the region thereof; means, responsive to a variation in the resistance of said first resistance element, for generating an output signal indicating that the conveyor system is moving a burning sheet of support material from the fusing apparatus; bridge circuit means having associated therewith said first resistance element and a second resistance element spaced from said first resistance element to compensate for normal thermal variations in the environment; and means for generating a substantially constant current to energize said bridge circuit means.
Claim 7
Dependent Claim
154 words
An electrophotographic printing machine of the type having a conveyor system arranged to move a sheet of support material having a toner powder image adhering substantially permanently thereon from a fusing apparatus adapted to heat and coalesce the toner powder image to the sheet of support material, wherein the improvement includes: a first resistance element adjacent the conveyor system, said resistance element having a variable effective resistance dependent upon thermal conditions in the region thereof; means, responsive to a variation in the resistance of said first resistance element, for generating an output signal indicating that the conveyor system is moving a burning sheet of support material from the fusing apparatus; bridge circuit means having associated therewith said first resistance element and a second resistance element spaced from said first resistance element to compensate for normal thermal variations in the environment; and means for generating a substantially constant current to energize said bridge circuit means.
Claim 8
Dependent Claim
45 words
A printing machine as recited in claim 5, further including means, responsive to said signal generating means, for deactuating the printing machine and displaying the output signal to alert a printing machine operator that a burning sheet exited the fusing apparatus on the conveyor system.
Claim 9
Dependent Claim
47 words
A printing machine as recited in claim 5 wherein said signal generating means includes a voltage comparator arranged to provide a digital output corresponding to the variation in first resistance of said resistance element to indicate the presence of the burning sheet on the moving conveyor system.
Claim 10
Dependent Claim
21 words
A printing machine as recited in claim 7, wherein said first resistance element is, preferably, made from an elongated tungsten wire.
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) | 1977-04-15 | 1977-10-15 | 1978-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-15 | 1981-10-15 | 1982-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-15 | 1985-10-15 | 1986-04-16 | $7700.00 | Window Closed / Lapsed |