Patent ID: 7576532

Claim:
A motion transducer comprising: a) one or more electromagnetic coils provided on a first element, each of said coils having a magnetic axis of symmetry, b) a conducting surface provided on a second element longitudinally moveable with respect to said first element, said surface oriented so as not to be normal to the said magnetic axis or axes of symmetry of said electromagnetic coil or coils, c) first means to excite said coil with an alternating voltage or current, d) second means to detect the impedance of said coil or coils using said first means to excite said coil, and e) third means to interpret detected impedance of said coil in terms of relative displacement of said conducting surface with respect to said coil, f) said conducting surface defines an axially spaced sequence of single planes inclined to a linear axis defined by said second element, g) and a selected number of said electromagnetic coils being provided and being axially spaced, in a sequence or sequences on said first element, and extending in two rows, at opposite sides of said axis, said planes having varied angularity and spaced apart axially, h) the coils being electrically connected to combine coil outputs thereby removing the effect of any lateral movement of said second element.