US4005359A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resonant frequency measuring device for gauging coating thickness
Assignee: Individual
•
Filing: 1975-11-07
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Granted: 1977-01-25
•
Expires: 1995-11-07
Abstract
Abstract An electronic thickness gauge for measuring the coating thickness over magnetic and over conductive, non-magnetic substrates by measuring the movement of the low-frequency hump in the response curve for an over-coupled, double-tuned, open-faced transformer when the above-mentioned substrates are placed across the gap between the transformer pole-faces.
Inventors
- 👤 William N. Smoot
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:54
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/02; G01B7/06; G01B7/10; G01B7/105; G01N; G01N27/00; G01N27/72
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
112 words
An electronic coating guage for measuring the thickness of a coating on a conductive, non-magnetic or magnetic substrate comprising: double-tuned over-coupled transformer means with a primary and a secondary winding each tuned to the same frequency, said transformer means having a U-shaped core which is adapted to have its open face flush with the coating of the substrate to be tested; A.c. input means for applying an A.C. signal to said primary winding; and means for measuring the voltage response at said secondary winding of said transformer means; said measuring means providing changes in the resonant frequency response characteristics of said transformer, which changes are indicative of the thickness of said coating.
Claim 2
Dependent Claim
112 words
An electronic coating guage for measuring the thickness of a coating on a conductive, non-magnetic or magnetic substrate comprising: double-tuned over-coupled transformer means with a primary and a secondary winding each tuned to the same frequency, said transformer means having a U-shaped core which is adapted to have its open face flush with the coating of the substrate to be tested; A.c. input means for applying an A.C. signal to said primary winding; and means for measuring the voltage response at said secondary winding of said transformer means; said measuring means providing changes in the resonant frequency response characteristics of said transformer, which changes are indicative of the thickness of said coating.
Claim 3
Dependent Claim
67 words
An electronic coating gauge as defined in claim 1, wherein said A.C. input means comprises: voltage-controlled-oscillator means for applying an A.C. signal to said primary winding; and feedback means taking a signal from said voltage-measuring means and applying it to said voltage-controlled-oscillator means to control the frequency of the A.C. output therefrom in accordance with the increases and decreases of the signal from said voltage measuring means.
Claim 4
Dependent Claim
48 words
An electronic coating gauge as defined in claim 1, wherein said voltage-measuring means comprises: means for rectifying the A.C. voltage response; non-linear conversion means for converting the signal from said rectifying means to a suitable scale; and milliammeter means for measuring the voltage from said non-linear conversion means.
Claim 5
Dependent Claim
24 words
An electronic coating guage as defined in claim 2, wherein the frequency of said voltage-controlled oscillator is measured and converted to a thickness measurement.
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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) | 1980-01-25 | 1980-07-26 | 1981-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-25 | 1984-07-26 | 1985-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-25 | 1988-07-26 | 1989-01-25 | $7700.00 | Window Closed / Lapsed |