Detector for non-ferrous metals with reduced false positive responses
US7148692B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 20, 2004 |
| Grant date | Dec 12, 2006 |
| Priority date | — |
| Expiry date | Oct 20, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/15
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A metal detector for detecting objects that are composed of non-ferrous metals. The metal detector provides for a reduced rate of false positive responses to objects composed of ferrous metals. A preferred metal detector according to the invention includes a transmitter for transmitting a time-varying electromagnetic signal and a receiver for receiving a responsive time-varying electromagnetic signal produced by the metal object. The metal detector also includes an analyzer for determining the resistive and reactive components of the responsive signal as respective first and second functions of the spatial position of the detector. A module for determining and comparing rates of change of the first and second functions at one or more spatial positions is included. Preferably, when the rates of change are the first derivatives or slopes of the functions, and when these are of the same sign, a result indicating that the metal object is non-ferrous is provided by the module.A preferred method for identifying with an improved degree of reliability a non-ferrous metal object versus a ferrous object. The resistive and the reactive components of the responsive electromagnetic signal are d…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.