Patents Assigned to Compass Electronics Corporation
  • Patent number: 4255711
    Abstract: A unitary balanced-inductor system for use in the search head of an electronic metal detector, having a transmit coil, a smaller, preferably concentric cancel coil of opposite polarity, and a yet smaller receive coil inductively decoupled from the combined transmit and cancel coils. The cancel coil preferably has a smaller number of turns and is located in a slightly higher plane than is the transmit coil, while the receive coil may be placed in a slightly lower plane than the transmit coil, to provide adequate sensitivity to the presence of conductive or magnetic objects separated from the search head without unacceptably high sensitivity to similar objects relatively close to the search head. A closed loop load coil located between portions of the transmit coil and the cancel coil may be used to provide an inductive load on the transmit coil thereby further reducing the sensitivity of the search head to targets in close proximity to the load coil.
    Type: Grant
    Filed: May 15, 1979
    Date of Patent: March 10, 1981
    Assignee: Compass Electronics Corporation
    Inventor: Fredrick H. Thompson