Patents by Inventor Rollin James Parker

Rollin James Parker has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Moving magnet electroacoustic transducer
    Patent number: 3937904
    Abstract: A transducer device such as a loudspeaker or microphone has a U-shaped core of magnetically permeable material with attached pole pieces defining a gap and a stationary electrical coil around the core. A permanent magnet is positioned for movement through the central portion of the gap as directed by a variable magnetic field within the gap. The permanent magnet has diagonally positioned poles of like magnetic orientation to provide a north-south pole combination facing one of the pole pieces and a complementary south-north pole combination facing the other pole piece.
    Type: Grant
    Filed: August 7, 1974
    Date of Patent: February 10, 1976
    Assignee: Hitachi Magnetics Corporation
    Inventor: Rollin James Parker