US3794808A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power supply circuit for a heating element
Assignee: Hewlett Packard Japan Inc
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Filing: 1972-08-02
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Granted: 1974-02-26
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Expires: 1992-08-02
Abstract
Abstract An improved high-efficiency power supply for a heating element includes charge, discharge, and comparator circuits. The comparator circuit provides the proper duty cycle and controls the power to the heater for keeping its temperature nearly constant over a wide range of input voltages. Changing the value of the components of the charge and discharge circuits alters the power supplied to the heating element.
Inventors
- 👤 S Takagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:45
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/40; G05F1/44; H; H02; H02M; H02M3/00; H02M3/02; H02M3/04; H02M3/10
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
131 words
A power supply for a heating element comprising: a heating element; a power source for energizing the heating element; a first switch means for repetitively connecting and disconnecting with a controllable duty cycle the heating element and the power source; means for generating a substantially constant reference voltage; sampling means for sampling the voltage of the power source; and a comparator means for comparing the sampled voltage from the power source with the constant reference voltage and increasing the duty cycle of the first switch means in response to decreases in sampled voltage from the power source relative to the constant reference voltage and for decreasing the duty cycle of the first switch means in response to increases in sampled voltage from the power source relative to the constant reference voltage.
Claim 2
Dependent Claim
131 words
A power supply for a heating element comprising: a heating element; a power source for energizing the heating element; a first switch means for repetitively connecting and disconnecting with a controllable duty cycle the heating element and the power source; means for generating a substantially constant reference voltage; sampling means for sampling the voltage of the power source; and a comparator means for comparing the sampled voltage from the power source with the constant reference voltage and increasing the duty cycle of the first switch means in response to decreases in sampled voltage from the power source relative to the constant reference voltage and for decreasing the duty cycle of the first switch means in response to increases in sampled voltage from the power source relative to the constant reference voltage.
Claim 3
Dependent Claim
103 words
A power supply as in claim 1 wherein said comparator means includes: a resistor and a capacitor serially connected with said power source; second switch means connected across the capacitor; means for recurringly actuating the second switch means to discharge the capacitor; and comparator means for comparing the voltage across the capacitor with that of the constant reference voltage, for closing said first switch means in response to the voltage across the capacitor being not greater than the constant reference voltage, and for opening said first switch means in response to the voltage across the capacitor being greater than the constant reference voltage.
Claim 4
Dependent Claim
25 words
A power supply as in claim 1 wherein said constant electrical power source means includes a variable voltage divider connEcted across a constant voltage supply.
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) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |