US4149057A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable power control microwave oven
Assignee: Goodman Co LP
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Filing: 1977-06-27
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Granted: 1979-04-10
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Expires: 1997-06-27
Abstract
Abstract A microwave oven control system in which the average microwave power may be selected by selecting different duty cycles of a cyclically closing semiconductor switch controlling the AC power supplied to a microwave magnetron anode power supply which has a saturable high voltage transformer with input current surges to said power supply being minimized by turning on said switch in the region a voltage peak of said AC power and with the cycle time of said switch being greater than the AC power cycle time but being substantially less than the thermal response time of a food body being cooked by microwave energy so that changing the duty cycle can change the power applied to the food body rapidly in the event that undesired results such as boiling over or burning of the food body are observed.
Inventors
- 👤 Rex E. Fritts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:36
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/66; H05B6/666; H05B6/68; H05B2206/00; H05B2206/04; H05B2206/043
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
108 words
A microwave oven comprising: a cavity having an access aperture and a closure member; a source of microwave energy comprising a magnetron coupled to said cavity; a power supply for said magnetron comprising a transformer; semiconductor switch means for cyclically connecting said transformer at a first cycle rate greater than 1 in 10 seconds to a source of AC power having a second cycle rate higher than said first cycle rate; and means for turning said switch on at a predetermined phase angle of one polarity of said AC power and turning said switch off at a predetermined phase angle of the opposite polarity of said AC power.
Claim 2
Dependent Claim
108 words
A microwave oven comprising: a cavity having an access aperture and a closure member; a source of microwave energy comprising a magnetron coupled to said cavity; a power supply for said magnetron comprising a transformer; semiconductor switch means for cyclically connecting said transformer at a first cycle rate greater than 1 in 10 seconds to a source of AC power having a second cycle rate higher than said first cycle rate; and means for turning said switch on at a predetermined phase angle of one polarity of said AC power and turning said switch off at a predetermined phase angle of the opposite polarity of said AC power.
Claim 3
Dependent Claim
18 words
The microwave oven in accordance with claim 1 wherein: said transformer feeds a voltage doubler supplying said magnetron.
Claim 4
Dependent Claim
17 words
The microwave oven in accordance with claim 1 wherein: said transformer has an output power regulating characteristic.
Claim 5
Dependent Claim
14 words
The microwave oven in accordance with claim 1 wherein: said switch is a thyristor.
Claim 6
Dependent Claim
25 words
The microwave oven in accordance with claim 1 wherein: said semiconductor switch means has an on-off duty cycle which is changed by manual control means.
Claim 7
Dependent Claim
102 words
A microwave oven comprising: a cavity having an access aperture and a closure member; a source of microwave energy comprising a magnetron coupled to said cavity; a power supply for said magnetron comprising a transformer; semiconductor switch means for cyclically connecting said transformer in a first cycle having a periodicity between 5. and 1 second to a source of AC power having a second cycle whose periodicity is at least an order of magnitude less than said first cycle periodicity; and means for turning said switch on and off respectively at different predetermined phases during respectively opposite polarities of said AC power.
Claim 8
Dependent Claim
102 words
A microwave oven comprising: a cavity having an access aperture and a closure member; a source of microwave energy comprising a magnetron coupled to said cavity; a power supply for said magnetron comprising a transformer; semiconductor switch means for cyclically connecting said transformer in a first cycle having a periodicity between 5. and 1 second to a source of AC power having a second cycle whose periodicity is at least an order of magnitude less than said first cycle periodicity; and means for turning said switch on and off respectively at different predetermined phases during respectively opposite polarities of said AC power.
Claim 9
Dependent Claim
17 words
The microwave oven in accordance with claim wherein: said transformer feeds a voltage doubler supplying said magnetron.
Claim 10
Dependent Claim
17 words
The microwave oven in accordance with claim 6 wherein: said transformer has an output power regulating characteristic.
Claim 11
Dependent Claim
14 words
The microwave oven in accordance with claim 6 wherein: said switch is a thyristor.
Claim 12
Dependent Claim
25 words
The microwave oven in accordance with claim 6 wherein: said semiconductor switch means has an on-off duty cycle which is changed by manual control 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) | 1982-04-09 | 1982-10-09 | 1983-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-09 | 1986-10-09 | 1987-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-09 | 1990-10-09 | 1991-04-10 | $7700.00 | Window Closed / Lapsed |