US3737770A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microwave thickness measuring device utilizing two resonant cavities on either side of the test piece
Assignee: COMMISS A LENERGIE
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Filing: 1970-11-27
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Granted: 1973-06-05
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Expires: 1990-11-27
Abstract
Abstract A device for measuring a displacement or the thickness of a sheet comprises a microwave test cavity resonator whose resonance frequency is controlled by said displacement or thickness and a microwave reference cavity resonator. A saw tooth modulated microwave generator supplies microwave energy to both cavities. First and second detector means detect the transmission of power by the test cavity and the reference cavity respectively and the volume and resonance frequency of the reference cavity are automatically adjusted in order to cause said transmissions to coincide in time.
Inventors
- 👤 M Masson
- 👤 R Warlop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:08
CPC Classifications
G; G01; G01B; G01B15/00; G01B15/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
182 words
A device for measuring the thickness of a conductive strip, comprising: two test cavity resonators located substantially symmetrically on opposite sides of said strip, opposite sides of said strip constituting one wall of each of said test cavities, a microwave reference cavity resonator having a movable wall, a microwave generator for supplying microwave energy to said test cavities and to said reference cavity, means for generating a sawtooth voltage and frequency modulating said microwave generator by said sawtooth voltage, two first detector means each associated with a respective one of said test cavities for detecting transmission of microwave power by said respective one of said test cavities, second detector means associated with said reference cavity for detecting transmission of power by said reference cavity, actuating means for moving said movable wall of said reference cavity, means responsive to the time difference between occurrence of microwave transmission of microwave power by said reference cavity and the average time of occurrences of microwave transmissions by said two test cavities for controlling said actuating means in a direction to bring said time difference to zero.
Claim 2
Independent Claim
182 words
A device for measuring the thickness of a conductive strip, comprising: two test cavity resonators located substantially symmetrically on opposite sides of said strip, opposite sides of said strip constituting one wall of each of said test cavities, a microwave reference cavity resonator having a movable wall, a microwave generator for supplying microwave energy to said test cavities and to said reference cavity, means for generating a sawtooth voltage and frequency modulating said microwave generator by said sawtooth voltage, two first detector means each associated with a respective one of said test cavities for detecting transmission of microwave power by said respective one of said test cavities, second detector means associated with said reference cavity for detecting transmission of power by said reference cavity, actuating means for moving said movable wall of said reference cavity, means responsive to the time difference between occurrence of microwave transmission of microwave power by said reference cavity and the average time of occurrences of microwave transmissions by said two test cavities for controlling said actuating means in a direction to bring said time difference to zero.
Claim 3
Dependent Claim
140 words
A device according to claim 1, wherein said control means comprise: two first flip-flop circuits each connected to a respective one of said first detector means and being set in response to transmission of power through the respective one of said test cavities during each sawtooth voltage and reset at the end of each sawtooth voltage, a second flip-flop circuit connected to said second detector means being set in response to transmission of power through said reference cavity during each sawtooth voltage and reset at the end of each sawtooth voltage, and comparator means controlling said actuating means, said comparator means providing control signals each in proportion to the time difference between settings of said second flip-flop circuit during a sawtooth voltage and one-half the interval between the settings of said two first flip-flop circuits during the same sawtooth voltage.
References Cited (Backward Citations)
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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) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |