Patent DE698002C successfully refreshed from Google Patents.
Patent EP0263653A2 successfully refreshed from Google Patents.
EP0263653A2
Expired / Lapsed
EP
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Copier fuser control
Assignee: Xerox Corp
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Filing: 1987-10-02
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Granted: —
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Expires: 2007-10-02
Abstract
Abstract A fuser temperature control using a resistive bridge driven power circuit. At the beginning of each positive half cycle of the AC line voltage, the possible firing of a triac (104) is delayed by 1090 microseconds. During this delay, the fuser temperature is checked by measuring the foil heaters resistance with a DC bridge circuit (102). One leg of this bridge circuit contains the foil heater (100). The other leg of the bridge has a potentiometer (110) to set the temperature of the fuser. The output of the bridge circuit is fed into a differential comparator (102) and D-type flip-flop (112). This combination gives high gain with very little sensitivity to noise. The differential comparator checks the fuser temperature (foil resistance) relative to the set point temperature (set point potentiometer). It determines whether the fuser temperature is above or below the set point temperature. The D-type flip-flop latches this information to either enable or disable the triac triggering circuitry for each full cycle of the line voltage. When the fuser temperature is below the set point temperature, power is enabled to heat the fuser. When the fuser temperature is above the set point temperature it is disabled to cool the fuser. This power decision is made at a rate of 60 Hz in order to keep up with the fusers instant-on characteristics.
Inventors
- 👤 Darrel R. Rathbun
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 06:18
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/2401; G03; G03G; G03G15/00; G03G15/20; G03G15/2003; G03G15/2014; G03G15/2039
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
261 words
An electrostatic copying machine having pressure fusing apparatus of the type including an instantly heated fuser roll and a pressure back-up roll defining a nip through which support material bearing toner images is passed for fusing the toner images onto the support material, the fuser roll being raised approximately 120°C in less than 10 seconds, the instantly heated fuser roll including a hollow, relatively thin cylinder, the cylinder having an outside and an inside surface, the cylinder enclosing ambient air, a source of thermal energy affixed by an adhesive capable of withstanding a high temperature of at least 190°C to either the outside or inside surface of said cylinder, the source of thermal energy being a heating circuit element, the resistance of the heating circuit element varying approximately 20% as the temperature of the heated fuser roll varies from temperature to fusing temperature, a control for the heating circuit element including: a differential bridge circuit, the heating circuit element electrically connected to one leg of the differential bridge circuit, a variable resistor electrically connected to a second leg of the differential bridge circuit, a triac electrically connected to the heating circuit element to apply heating power to the heating circuit element, a differential comparator electrically connected to the differential bridge circuit to fire the triac, an AC power source, a zero crossing detector for determining each positive going cycle of the AC power source, and a timing logic connected to the zero crossing detector and the differential comparator to trigger the triac at least 50 microseconds after the time of crossover.
Claim 2
Dependent Claim
261 words
An electrostatic copying machine having pressure fusing apparatus of the type including an instantly heated fuser roll and a pressure back-up roll defining a nip through which support material bearing toner images is passed for fusing the toner images onto the support material, the fuser roll being raised approximately 120°C in less than 10 seconds, the instantly heated fuser roll including a hollow, relatively thin cylinder, the cylinder having an outside and an inside surface, the cylinder enclosing ambient air, a source of thermal energy affixed by an adhesive capable of withstanding a high temperature of at least 190°C to either the outside or inside surface of said cylinder, the source of thermal energy being a heating circuit element, the resistance of the heating circuit element varying approximately 20% as the temperature of the heated fuser roll varies from temperature to fusing temperature, a control for the heating circuit element including: a differential bridge circuit, the heating circuit element electrically connected to one leg of the differential bridge circuit, a variable resistor electrically connected to a second leg of the differential bridge circuit, a triac electrically connected to the heating circuit element to apply heating power to the heating circuit element, a differential comparator electrically connected to the differential bridge circuit to fire the triac, an AC power source, a zero crossing detector for determining each positive going cycle of the AC power source, and a timing logic connected to the zero crossing detector and the differential comparator to trigger the triac at least 50 microseconds after the time of crossover.
Claim 3
Dependent Claim
200 words
In an electrostatic copying machine having pressure fusing apparatus of the type including an instantly heated fuser roll and a pressure back-up roll defining a nip through which support material bearing toner images is passed for fusing the toner images onto the support material, the fuser roll being raised approximately 120°C in less than 10 seconds, the instantly heated fuser roll including: a hollow, relatively thin cylinder, the cylinder having an outside and an inside surface, the cylinder enclosing ambient air, a source of thermal energy affixed by a high temperature adhesive to either the outside or inside surface of said cylinder, the temperature range being up to at least 190°C the source of thermal energy being a heating circuit element, and a control for the heating circuit element comprising: a differential bridge circuit, the heating circuit element electrically connected to one leg of the differential bridge circuit, a variable resistor electrically connected to another leg of the differential bridge circuit, a triac electrically connected to the heating circuit element to apply heating power to the heating circuit element, and a differential comparator electrically connected to the differential bridge circuit to fire the triac to control the heating circuit element.
Claim 4
Dependent Claim
200 words
In an electrostatic copying machine having pressure fusing apparatus of the type including an instantly heated fuser roll and a pressure back-up roll defining a nip through which support material bearing toner images is passed for fusing the toner images onto the support material, the fuser roll being raised approximately 120°C in less than 10 seconds, the instantly heated fuser roll including: a hollow, relatively thin cylinder, the cylinder having an outside and an inside surface, the cylinder enclosing ambient air, a source of thermal energy affixed by a high temperature adhesive to either the outside or inside surface of said cylinder, the temperature range being up to at least 190°C the source of thermal energy being a heating circuit element, and a control for the heating circuit element comprising: a differential bridge circuit, the heating circuit element electrically connected to one leg of the differential bridge circuit, a variable resistor electrically connected to another leg of the differential bridge circuit, a triac electrically connected to the heating circuit element to apply heating power to the heating circuit element, and a differential comparator electrically connected to the differential bridge circuit to fire the triac to control the heating circuit element.
Claim 5
Dependent Claim
22 words
The control of Claim 1 or 2 wherein the variable resistor is a set point resistor set to calibrate the differential bridge.
Claim 6
Dependent Claim
33 words
The control of any preceding Claim wherein the resistance of the heating circuit element varies approximately between 20% as the temperature of the heated fuser roll varies from start up to maximum temperature.
Claim 7
Dependent Claim
17 words
The control of Claim 4 wherein the heating circuit element varies approximately between 19 and 23 ohms.
References Cited (Backward Citations)
No citation records indexed.
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