US3735092A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuser control circuit for copying apparatus
Assignee: Xerox Corp
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Filing: 1971-10-18
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Granted: 1973-05-22
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Expires: 1991-10-18
Abstract
Abstract An arrangement for controlling the fuser heat source in an electrostatic type reproduction machine to maintain fuser temperatures within a desired operating range and protect the reproduction machine in the event fuser temperatures become too high. The arrangement includes a thermistor to sense temperature conditions within the fuser, an amplifier to amplify the thermistor signal output to a level permitting relatively inexpensive switching devices to be used directly as fuser and reproduction machine controls without the need for relatively sensitive and correspondingly expensive intermediate comparator circuitry, and switching devices for operating the fuser heat source and controlling the reproduction machine in response to predetermined fuser temperature conditions.
Inventors
- 👤 R Traister
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:53
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G03; G03G; G03G15/00; G03G15/20; G03G15/2003
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
222 words
In a copying apparatus having a fuser for fixing toner developed images on the copy output of said apparatus, the combination comprising circuit means for generating a control signal proportional to temperature conditions in said fuser, said circuit means including a temperature variable resistor in heat exchange relation with said fuser, the resistive change of said resistor in response to changes in temperature in said fuser normally being relatively small within the operating temperature range of said fuser whereby the sensitivity of said circuit means is relatively low in said fuser operating temperature range; means for amplifying the signal output of said circuit means at least in said fuser operating temperature range whereby to avoid the need for relatively sensitive output comparator circuitry and instead permit use of relatively simple switching means; means for heating said fuser; means for operating said fuser heating means in response to signals from said amplifier means whereby to maintain said fuser in a predetermined operating temperature range; and control means for said copying apparatus, said control means including switching means operative to prevent actuation of said copying apparatus while temperature of said fuser is below a predetermined minimum, said switching means being operative on a preset signal from said amplifier means reflecting attainment of said predetermined minimum fuser temperature to enable operation of said copying apparatus.
Claim 2
Dependent Claim
222 words
In a copying apparatus having a fuser for fixing toner developed images on the copy output of said apparatus, the combination comprising circuit means for generating a control signal proportional to temperature conditions in said fuser, said circuit means including a temperature variable resistor in heat exchange relation with said fuser, the resistive change of said resistor in response to changes in temperature in said fuser normally being relatively small within the operating temperature range of said fuser whereby the sensitivity of said circuit means is relatively low in said fuser operating temperature range; means for amplifying the signal output of said circuit means at least in said fuser operating temperature range whereby to avoid the need for relatively sensitive output comparator circuitry and instead permit use of relatively simple switching means; means for heating said fuser; means for operating said fuser heating means in response to signals from said amplifier means whereby to maintain said fuser in a predetermined operating temperature range; and control means for said copying apparatus, said control means including switching means operative to prevent actuation of said copying apparatus while temperature of said fuser is below a predetermined minimum, said switching means being operative on a preset signal from said amplifier means reflecting attainment of said predetermined minimum fuser temperature to enable operation of said copying apparatus.
Claim 3
Dependent Claim
43 words
The copying apparatus according to claim 1 in which said copying apparatus control means includes second switching means operative to shut down said copying apparatus in response to a second preset signal from said amplifier means reflecting a predetermined overtemperature in said fuser.
Claim 4
Dependent Claim
44 words
The copying apparatus according to Claim 1 including means for monitoring operation of said temperature variable resistor operative on failure of said resistor to abort said amplifying means to generate said second preset signal whereby said second switching means shuts down said copying apparatus.
Claim 5
Dependent Claim
221 words
In a copying apparatus having a fuser for fixing toner developed images on the copy output of said apparatus, the combination comprising circuit means for generating a control signal proportional to temperature conditions in said fuser, said circuit means including a temperature variable resistor in heat exchange relation with said fuser, the resistive change of said resistor in response to changes in temperature in said fuser normally being relatively small within the operating temperature range of said fuser whereby the sensitivity of said circuit means is relatively low in said fuser operating temperature range; means for amplifying the signal output of said circuit means at least in said fuser operating temperature range whereby to avoid the need for relatively sensitive output comparator circuitry and instead permit use of relatively simple switching means; means for heating said fuser; and switching means for controlling said fuser heating means, said switching means rendering said fuser heating means inoperative in response to a first amplifier means signal reflecting attainment of normal operating temperature in said fuser; said amplifying means comprising a variable voltage amplifier gated to operate in response to a preset unamplified control signal from said circuit means reflecting attainment of minimum operating temperature in said fuser so that at fuser temperatures below said minimum operating temperature, said amplifier assumes a signal blocking condition.
Claim 6
Dependent Claim
221 words
In a copying apparatus having a fuser for fixing toner developed images on the copy output of said apparatus, the combination comprising circuit means for generating a control signal proportional to temperature conditions in said fuser, said circuit means including a temperature variable resistor in heat exchange relation with said fuser, the resistive change of said resistor in response to changes in temperature in said fuser normally being relatively small within the operating temperature range of said fuser whereby the sensitivity of said circuit means is relatively low in said fuser operating temperature range; means for amplifying the signal output of said circuit means at least in said fuser operating temperature range whereby to avoid the need for relatively sensitive output comparator circuitry and instead permit use of relatively simple switching means; means for heating said fuser; and switching means for controlling said fuser heating means, said switching means rendering said fuser heating means inoperative in response to a first amplifier means signal reflecting attainment of normal operating temperature in said fuser; said amplifying means comprising a variable voltage amplifier gated to operate in response to a preset unamplified control signal from said circuit means reflecting attainment of minimum operating temperature in said fuser so that at fuser temperatures below said minimum operating temperature, said amplifier assumes a signal blocking condition.
Claim 7
Dependent Claim
109 words
In a copying apparatus having a fuser for fixing toner developed images on the copy output of said apparatus, the combination comprising: circuit means for generating a control signal proportional to temperature conditions of said fuser, said circuit means including a temperature variable resistor in heat exchange relation with said fuser; means for heating said fuser; switching means for operating said fuser heating means in response to said circuit means control signals whereby to maintain said fuser in a predetermined temperature range during operation of said copying apparatus, and means monitoring said temperature variable resistor operative on failure of said resistor to terminate operation of said fuser heating means.
Claim 8
Dependent Claim
109 words
In a copying apparatus having a fuser for fixing toner developed images on the copy output of said apparatus, the combination comprising: circuit means for generating a control signal proportional to temperature conditions of said fuser, said circuit means including a temperature variable resistor in heat exchange relation with said fuser; means for heating said fuser; switching means for operating said fuser heating means in response to said circuit means control signals whereby to maintain said fuser in a predetermined temperature range during operation of said copying apparatus, and means monitoring said temperature variable resistor operative on failure of said resistor to terminate operation of said fuser heating means.
Claim 9
Dependent Claim
35 words
The copying apparatus according to claim 5 including means to delay response of said resistor monitoring means whereby to avoid premature response of said resistor monitoring means and shut down of said fuser heating means.
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) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |