Walk-through metal detector
US4906973A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1988 |
| Grant date | Mar 6, 1990 |
| Priority date | — |
| Expiry date | Apr 29, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/2474
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A walk-through metal detector comprising an array module supporting transmit and receive coil arrays. Surrounding the array module, yet not touching it, is an outer shell protecting the array module from contact. A passageway tube passes through the opening in the array module, and is supported by the outer shell, further isolating the array module from mechanical vibration. The array module has a relatively high resonant frequency; thus, vibration induced signals are higher in frequency than actual target signals and are disregarded by the detection circuitry. The metal detector also includes a bypass chute, mechanically isolated from the array module, in which metallic objects may be placed and transported to the exit of the passageway without setting any alarms. The array module supports a balanced transmit and receive coil array for insensitivity to external electromagnetic interference. Alternate coil configurations may be selected by the operator to reduce the detector's sensitivity at predetermined portions of the passageway. The detection circuitry of the metal detector includes quadrature phase demodulators for separating target signals into components caused by eddy curre…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.