US3821594A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two step magnetron start circuit
Assignee: General Electric Co
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Filing: 1973-03-28
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Granted: 1974-06-28
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Expires: 1993-03-28
Abstract
Abstract A control arrangement for stepped energizing of a magnetron in a microwave oven includes means to delay the application of the full high voltage to the magnetron to insure operation in the desired oscillating mode. Such delay is accomplished by providing a thermistor coupled serially with an input terminal of a voltage doubler, such that upon magnetron conduction, the current flowing through the thermistor causes a decrease in resistance therein which in turn produces an increase in the doubler output voltage, whereupon the reaching of a predetermined level thereof, a relay effects switching to apply full line voltage to the voltage doubler input terminals.
Inventors
- 👤 R Webb
- 👤 J Roberts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:30
CPC Classifications
H; H01; H01H; H01H43/00; H01H43/30; H01H43/308; H05; H05B; H05B6/00; H05B6/64; H05B6/66; H05B6/68
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
174 words
A control arrangement for energizing a magnetron comprising: a neutral terminal and a pair of line voltage terminals for supplyig electric power; a full-wave voltage multiplier having a pair of input terminals and a pair of output terminals, one of the input terminals being coupled with a first of said line voltage terminals; a magnetron having an anode and a cathode coupled respectively with the output terminals of said multiplier; relay means responsive to voltage to become energized at a predetermined level thereof, said relay means being coupled serially with said magnetron and further, having a set of contacts, in the de-energized state of the relay means to couple the second of said multiplier input terminals to said neutral terminal, and in the energized state to couple said second multiplier terminal to said second line terminal; and delay means coupled serially with said neutral terminal and said relay means contacts for allowing a time delay before said relay means becomes energized, thereby allowing the magnetron to warm up before full voltage is applied thereto.
Claim 2
Dependent Claim
174 words
A control arrangement for energizing a magnetron comprising: a neutral terminal and a pair of line voltage terminals for supplyig electric power; a full-wave voltage multiplier having a pair of input terminals and a pair of output terminals, one of the input terminals being coupled with a first of said line voltage terminals; a magnetron having an anode and a cathode coupled respectively with the output terminals of said multiplier; relay means responsive to voltage to become energized at a predetermined level thereof, said relay means being coupled serially with said magnetron and further, having a set of contacts, in the de-energized state of the relay means to couple the second of said multiplier input terminals to said neutral terminal, and in the energized state to couple said second multiplier terminal to said second line terminal; and delay means coupled serially with said neutral terminal and said relay means contacts for allowing a time delay before said relay means becomes energized, thereby allowing the magnetron to warm up before full voltage is applied thereto.
Claim 3
Dependent Claim
31 words
The control arrangement of claim 1 wherein a field coil is coupled in parallel with said relay means for providing the necessary magnetic field for the operation of said magnetron tube.
Claim 4
Dependent Claim
13 words
The control arrangement of claim 1 wherein the delay means is a thermistor.
Claim 5
Dependent Claim
27 words
The control arrangement of claim 1 wherein the delay means is a heating element and coupled in parallel therewith and responsive thereto is a normally-open bimetal switch.
Claim 6
Dependent Claim
187 words
In a microwave oven, a control arrangement for energizing a magnetron comprising: a neutral terminal and first and second line voltage terminals for supplying electric power; a voltage multiplier having a pair of input terminals and a pair of output terminals, one of said input terminals being coupled with said first line voltage terminals; a magnetron having an anode and a cathode coupled respectively with the output terminals of said multiplier; a field coil coupled serially with said magnetron across said multiplier output terminals; a relay switch having a set of contacts and further having a coil coupled in parallel with said field coil, the switch being responsive to the voltage across said field coil to become energized at a predetermined voltage level, in the de-energized state of the relay to couple the second multiplier input terminal to said neutral terminal, and in the energized state to coUple said second multiplier terminal to the second line terminal; and a thermistor coupled serially with said neutral terminal and said switch contacts for allowing a time delay before said switch becomes energized to effect gradual warm-up of said magnetron.
Claim 7
Dependent Claim
187 words
In a microwave oven, a control arrangement for energizing a magnetron comprising: a neutral terminal and first and second line voltage terminals for supplying electric power; a voltage multiplier having a pair of input terminals and a pair of output terminals, one of said input terminals being coupled with said first line voltage terminals; a magnetron having an anode and a cathode coupled respectively with the output terminals of said multiplier; a field coil coupled serially with said magnetron across said multiplier output terminals; a relay switch having a set of contacts and further having a coil coupled in parallel with said field coil, the switch being responsive to the voltage across said field coil to become energized at a predetermined voltage level, in the de-energized state of the relay to couple the second multiplier input terminal to said neutral terminal, and in the energized state to coUple said second multiplier terminal to the second line terminal; and a thermistor coupled serially with said neutral terminal and said switch contacts for allowing a time delay before said switch becomes energized to effect gradual warm-up of said magnetron.
Claim 8
Dependent Claim
198 words
In a microwave oven, a control arrangement for energizing a magnetron, said arrangement comprising: a neutral terminal and first and second line voltage terminals for coupling to a source of electric power; a full-wave voltage doubler having a pair of input terminals and a pair of output terminals, one of said input terminals being coupled with said first line voltage terminal; a current limiting resistor coupled serially with said first line terminal; a magnetron having an anode and a cathode coupled serially with the output terminals of said doubler; a field coil coupled serially with said magnetron across said doubler output terminals; a relay having a coil and a set of normally-open contacts, the coil being coupled in parallel with said field coil and responsive to the voltage thereacross to become energized at a predetermined voltage level, in the de-energized state of the relay to couple the second doubler input terminal to said neutral terminal, and in the energized state to couple said second doubler input terminal to the second line terminal; and a thermistor coupled serially with said neutral terminal for allowing a time delay before said relay becomes energized for effecting gradual warm-up of said magnetron.
Claim 9
Dependent Claim
198 words
In a microwave oven, a control arrangement for energizing a magnetron, said arrangement comprising: a neutral terminal and first and second line voltage terminals for coupling to a source of electric power; a full-wave voltage doubler having a pair of input terminals and a pair of output terminals, one of said input terminals being coupled with said first line voltage terminal; a current limiting resistor coupled serially with said first line terminal; a magnetron having an anode and a cathode coupled serially with the output terminals of said doubler; a field coil coupled serially with said magnetron across said doubler output terminals; a relay having a coil and a set of normally-open contacts, the coil being coupled in parallel with said field coil and responsive to the voltage thereacross to become energized at a predetermined voltage level, in the de-energized state of the relay to couple the second doubler input terminal to said neutral terminal, and in the energized state to couple said second doubler input terminal to the second line terminal; and a thermistor coupled serially with said neutral terminal for allowing a time delay before said relay becomes energized for effecting gradual warm-up of said magnetron.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |