Patent ID: 6584838
Filing Date: 2003-07-01
Classification: G01F

Abstract:
A sensing system for use with a boundary and protruding through an opening in the boundary, the sensing system comprising:a first magnet, said first magnet axially rotatable on a first axis, said first magnet having a magnetic moment with a nonzero component at a right angle to the axis; a linkage between a sensed phenomenon and the first magnet causing the first magnet to rotate in response to the sensed phenomenon; a second magnet having a magnetization, said second magnet axially rotatable on a second axis, said magnetization of the second magnet giving rise to a nonzero component at a right angle to the second axis, the first and second magnets juxtaposed in magnetic linkage so that the second magnet is urged to follow the first magnet in rotation; a divider separating the first and second magnets, the divider plugging the opening in the boundary; a magnetic field sensor positioned to sense axial magnetic field strength at a location offset from the second axis; the second magnet having a face proximal to the magnetic field sensor, the second magnet giving rise to a sensed magnetic field at the magnetic field sensor, the axial face of the second magnet shaped to provide a varying gap between the face of the second magnet and the magnetic field sensor as a function of an angle of rotation of the second magnet on the second axis, the shape of the face selected to provide a first gap at a first angular position, a second gap larger than the first gap at a second angular position, and a third gap smaller than the second gap at a third angular position, the difference between the first and third angular positions being greater than 200 degrees, the second angular position being between the first and third angular positions.