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High uniformity metal detector equipped with auxiliary receiver coils sensitive to metal masses passing close to them

  • US 5,406,259 A
  • Filed: 04/19/1993
  • Issued: 04/11/1995
  • Est. Priority Date: 11/19/1992
  • Status: Expired due to Term
First Claim
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1. Metal detector for detecting metal objects within a supervised area to be used at entrances of premises needing protection from an admission of armed persons and for other uses connected with an interception of metal objects, comprising at least one transmitter unit Tx and at least one receiver unit Rx placed on each side of said supervised area, each connected through amplifiers to a logic unit for analysis and control LAC where signals induced by a perturbation of a magnetic field within said supervised area are measured and compared wherein said metal detector further comprises at least one corrective receiver winding CC on each side of said supervised area, said at least one corrective receiver winding CC being used to provide information to said LAC unit about metal bodies in transit along paths close to said at least one corrective winding CC, said signals induced in said at least one corrective winding CC facilitating an application of suitable corrective coefficients K which render an interception sensitivity of said metal detector uniform throughout said supervised area by adjusting a gain of an amplifier amplifying signals induced within said at least one receiver unit Rx, even when more than one metal body is in simultaneous transit.

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