Patent ID: 8570028
Filing Date: 2013-10-29
Classification: G01D

Abstract:
1. A transducer for use in a position sensor, the transducer comprising: a resonator having an elongate magnetic field concentrating member and a resonator coil wound around the magnetic field concentrating member; a first coil operable, in use, to couple more strongly with a first portion of the magnetic field concentrating member positioned adjacent the first coil than with a second portion of the magnetic field concentrating member; and a second coil operable, in use, to couple more strongly with the second portion of the magnetic field concentrating member positioned adjacent the second coil than with the first portion of the magnetic field concentrating member, the second portion being spaced along the magnetic field concentrating member from the first portion; wherein the resonator is electrically separate from said first and second coils, and the resonator coil is wound around a third portion of said magnetic field concentrating member which third portion is located between said first and second portions; wherein one of the first and second coils is for exciting the resonator and the other one of the first and second coils is for sensing a signal generated by the resonator when excited; wherein, during use, the resonator and at least one of the first and second coils are relatively moveable along a measurement path that is different from a longitudinal axis of the elongate magnetic field concentrating member; wherein said at least one of the first and second coils extends along the measurement path and is patterned so that electromagnetic coupling between the resonator and said at least one of the first and second coils varies as a function of the relative position between the resonator and said at least one of the first and second coils along the measurement path.