Patent ID: 7521923

Claim:
A transducer for measuring a displacement along an axis of movement of a first part relative to a second part, consisting of: a magnetic source for generating a magnetic field consisting of a single magnetic device mounted to the first part having a single North and a single South pole in combination oriented in the direction of said axis of movement; at least two active magnetic field sensing devices mounted to the second part to be movable relative to the magnetic field, wherein said active magnetic field sensing devices are spaced in the direction of said axis, and wherein said at least two active magnetic field sensing devices are respective members of two groups of sensing devices; and a circuit arrangement to which said at least two active magnetic field sensing devices are connected, wherein the magnetic field sensing devices within a first group of the two groups of sensing devices are connected such that the polarity of an output response of all of the sensing devices of said first group to the magnetic field is the same, and wherein the devices within a second group of the two groups of sensing devices are connected such that the polarity of an output response of all the sensing devices of said second group to the magnetic field is the same, and wherein the polarity of an output response of one of said at least two active magnetic field sensing devices is opposite the polarity of an output response of at least one other of said at least two active magnetic field sensing devices when exposed to the magnetic field to generate an output signal dependent on the combined additive or subtractive contributions from all of said sensing devices.