US3842233A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microwave oven defrost circuit
Assignee: White Consolidated Industries Inc
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Filing: 1973-05-31
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Granted: 1974-10-15
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Expires: 1993-05-31
Abstract
Abstract An energization circuit for a microwave oven provides for microwave oven operation in cook and defrost modes. A start switch in series with a current limiting resistor prevents high current surges during initial energization of a transformer used to energize a magnetron that produces microwave energy, and a relay operated switch effects a current bypass of such resistor after initial transformer and magnetron energization. The energization circuit includes a selector switch for coupling the circuit in defrost configuration that includes a motor-controlled multiple stage energization circuit for the magnetron, such circuit having an on and off time for reducing the average level of microwave energy within the microwave cooking cavity to achieve food defrosting without cooking the same. A current limiting resistor is sequentially connected in the multiple stage energization circuit for preventing high current surges as the transformer and magnetron are cyclically energized in the defrost mode.
Inventors
- 👤 J Lamb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:38
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/6435; H05B6/74; H05B6/745
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
216 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by high-frequency energy emitted by a high-frequency energy generator, comprising means for connecting the energization circuit to a source of electric energy, means for coupling energy in the energization circuit to the high-frequency energy generator for energization of the same, selector switch means for coupling the energization circuit in a first configuration to provide a cooking function and in a second configuration to provide a defrost function, and cyclical switch means coupled to said selector switch means and energized thereby when the energization circuit is coupled in the defrost configuration for cyclically providing current to said means for coupling for effecting cyclical energization of the high-frequency energy generator, saiD cyclical switch means comprising current limiting means for limiting the current to said means for coupling, and said cyclical switch means upon energization by said selector switch means being operable in cyclical manner for providing current to said means for coupling via said current limiting means, then bypassing said current limiting means to provide maximum current to said means for coupling, and then interrupting current to said means for coupling, whereby at the initiation of each energization cycle of the high-frequency generator said current limiting means protects the same from current surges.
Claim 2
Dependent Claim
216 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by high-frequency energy emitted by a high-frequency energy generator, comprising means for connecting the energization circuit to a source of electric energy, means for coupling energy in the energization circuit to the high-frequency energy generator for energization of the same, selector switch means for coupling the energization circuit in a first configuration to provide a cooking function and in a second configuration to provide a defrost function, and cyclical switch means coupled to said selector switch means and energized thereby when the energization circuit is coupled in the defrost configuration for cyclically providing current to said means for coupling for effecting cyclical energization of the high-frequency energy generator, saiD cyclical switch means comprising current limiting means for limiting the current to said means for coupling, and said cyclical switch means upon energization by said selector switch means being operable in cyclical manner for providing current to said means for coupling via said current limiting means, then bypassing said current limiting means to provide maximum current to said means for coupling, and then interrupting current to said means for coupling, whereby at the initiation of each energization cycle of the high-frequency generator said current limiting means protects the same from current surges.
Claim 3
Dependent Claim
53 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by high-frequency energy emitted by a high frequency energy generator as set forth in claim 1, said cyclical switch means comprising means for bypassing said current limiting means after the beginning of each energization cycle of the generator.
Claim 4
Dependent Claim
59 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by high-frequency energy emitted by a high frequency energy generator as set forth in claim 2, further comprising a plurality of interlock switch means connected in the energization circuit for providing current flow therethrough only when the microwave oven door is closed and latched.
Claim 5
Dependent Claim
106 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by high-frequency energy emitted by a high-frequency energy generator as set forth in claim 3, further comprising start switch means for providing starting current in the energization circuit for effecting energization of the high-frequency energy generator, said start switch means comprising a current limiting resistor and a normally open switch coupled in series circuit relation, a relay operated switch connected in parallel with such series circuit, and a relay for operating said relay operated switch, said relay being connected to said start switch means for energization upon actuation of the latter.
Claim 6
Dependent Claim
64 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by high-frequency energy emitted by a high frequency energy generator as set forth in claim 2, wherein said cyclical switch means comprises electrical switch means for cyclically providing to the means for coupling an open circuit, a circuit including said means for limiting the current, and a closed circuit.
Claim 7
Dependent Claim
57 words
An energization circuit for a microwave oven in which cooking and defrosting functions are accomplished by a high-frequency energy emitted by a high frequency energy generator as set forth in claim 5, wherein said cyclical switch means further comprises a motor and a cam means mechanically connected thereto for controlling operation of said last mentioned switch 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) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |