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Alarm switch

  • US 5,977,873 A
  • Filed: 03/04/1998
  • Issued: 11/02/1999
  • Est. Priority Date: 03/04/1998
  • Status: Expired due to Term
First Claim
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1. A magnetic switch apparatus for detecting relative movement between first and second members, said apparatus comprising:

  • a switch assembly for mounting to the first member, said assembly includinga first switch element presenting a generally rod-shaped configuration,a second switch element presenting a generally disc-shaped configuration and having a contact surface,structure positioning said first switch element generally transverse to said contact surface and spaced therefrom,a ferromagnetic body shiftable between a switch-open position in which said body is out of contact with both of said first and second elements and a switch-closed position in which said body is in electrical contact with both said element and said contact surface; and

    a first magnet spaced from said contact surface and positioned for magnetically shifting said body to said switch-open position; and

    a second magnet for mounting to the second member and positioned on an opposed side of said contact surface relative to said first switch element, said second magnet being magnetically sufficient for shifting said body to said switch-closed position when the members are in an adjacent position, and for allowing said first magnet to shift said body to said switch-open position when the members are separated.

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