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US4303818A
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Microwave oven humidity sensing arrangement
Assignee: General Electric Co
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Filing: 1979-10-29
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Granted: 1981-12-01
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Expires: 1999-10-29
Abstract
Abstract A microwave oven including a resonant cavity humidity sensor operated by microwave energy sampled from the power produced for the cooking operation. The arrangement provides for a flow of moist air from the cooking cavity through an active resonant chamber and a flow of dry air from the atmosphere through a passive resonant chamber. Control circuitry governs the microwave energy flow into the cooking cavity in response to moisture conditions in the cavity so indicated by the sensor.
Inventors
- 👤 Peter H. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 07:45
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/6447; H05B6/6458
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
159 words
In a microwave oven, a microwave heating cavity; a source of microwave energy; a waveguide for coupling said source of microwave energy to said cavity; a pair of resonant microwave chambers, including an active chamber and a passive chamber; a splitter electromagnetically coupled to each of said waveguide and said active and passive chambers for sampling a portion of microwave energy from said source and coupling a substantially equal amount of the sample to each of said chambers; means for establishing direct communication between said cavity and said active chamber whereby humidity conditions in said cavity are represented in said active chamber and influence the strength of the electric field in said active chamber; means for sensing the field strength in each of said chambers and providing individual field strength signals corresponding thereto; and means for comparing the field strength signals from both said chambers and providing a comparator output signal indicative of the humidity condition in said cavity.
Claim 2
Dependent Claim
159 words
In a microwave oven, a microwave heating cavity; a source of microwave energy; a waveguide for coupling said source of microwave energy to said cavity; a pair of resonant microwave chambers, including an active chamber and a passive chamber; a splitter electromagnetically coupled to each of said waveguide and said active and passive chambers for sampling a portion of microwave energy from said source and coupling a substantially equal amount of the sample to each of said chambers; means for establishing direct communication between said cavity and said active chamber whereby humidity conditions in said cavity are represented in said active chamber and influence the strength of the electric field in said active chamber; means for sensing the field strength in each of said chambers and providing individual field strength signals corresponding thereto; and means for comparing the field strength signals from both said chambers and providing a comparator output signal indicative of the humidity condition in said cavity.
Claim 3
Dependent Claim
34 words
The invention of claim 1, further comprising control means for controlling said source of microwave energy with said comparator output signal as said signal varies in accordance with the humidity condition in said cavity.
Claim 4
Dependent Claim
33 words
The invention of claim 2, wherein said control means comprises means for receiving said field strength signals, summing them, comparing the results to a predetermined threshold value, and providing an excess threshold signal.
Claim 5
Dependent Claim
28 words
The invention of claim 3, wherein said control means further comprises means controlled by said excess threshold signal and effective for determining the operation of said energy source.
Claim 6
Dependent Claim
15 words
The invention of claim 1, wherein said splitter is electromagnetically coupled to said cooking cavity.
Claim 7
Dependent Claim
24 words
The invention of claim 1, wherein the coupling between said splitter and each said active and passive chambers is effected by a coupling aperture.
Claim 8
Dependent Claim
47 words
The invention of claim 1, wherein said waveguide, said active and passive chambers, and said power splitter are mounted on a wall of said cavity; said waveguide is electromagnetically coupled to said cavity; and said active and passive chambers are disposed on opposite sides of said splitter.
Claim 9
Dependent Claim
29 words
The invention of claim 1, wherein each of said means for sensing the field strength in each said chambers comprises an electric field detector extending into a respective chamber.
Claim 10
Dependent Claim
15 words
The invention of claim 1, wherein each of said chambers is vented to the atmosphere.
Claim 11
Dependent Claim
68 words
The invention of claim 9, wherein said cavity and said active chamber have a commmon wall section perforated to permit moisture in said cavity to enter said active chamber; another wall section of said active chamber is perforated to vent said active chamber to the atmosphere; and a pair of opposite wall sections of said passive chamber are perforated to enable circulation of air through said passive chamber.
Claim 12
Dependent Claim
45 words
The invention of claim 10, further comprising means for directing a flow of air in a plurality of paths, one of said paths extending through and ventilating said cavity and said active chamber and another of said paths extending through and ventilating said passive chamber.
Claim 13
Dependent Claim
33 words
The invention of claim 11, wherein said means for directing a flow of air in a plurality of paths is supplied with air from means provided for air cooling said microwave energy source.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-30 | 1985-06-01 | 1985-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-30 | 1989-06-01 | 1989-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-30 | 1993-06-01 | 1993-12-01 | $7700.00 | Window Closed / Lapsed |