Metal detector with feedback tuning
US4130792A · kind A · utility
20Cited by
8References
3Claims
0Family size
Inventor
Key dates
| Filing date | Sep 30, 1977 |
| Grant date | Dec 19, 1978 |
| Priority date | — |
| Expiry date | Sep 30, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/101
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Metal detector of the type having a tuned sensing loop which undergoes a shift in resonance and Q when brought into proximity to metal objects. In the absence of metal objects, the detector operates in a closed loop mode in which negative feedback is utilized to offset errors and maintain the excitation signal at an optimum frequency. Upon detection of a metal object, the system switches to an open loop mode in which the excitation signal remains at the optimum frequency and the output signal varies in accordance with the proximity of the object.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.