Patent ID: 7233140

Claim:
A position sensor assembly, comprising: a primary non ferromagnetic coil assembly including a coil form formed of a non ferromagnetic material, having an outer surface against which at least a portion of a coil is adapted to be wound, and having a primary coil wound around said outer surface, said primary non ferromagnetic coil assembly being coupled to a movable object of interest, and being movable according to movement of the movable object of interest; at least first and second stationary coil assemblies, each including a non ferromagnetic coil form, having an outer surface against which the coil is adapted to be wound, and each having a coil wound against said outer surface, said first and second stationary coil assemblies being located adjacent to said primary non ferromagnetic coil assembly; an electronics portion, producing electrical current to one of said coil assemblies, and receiving an induced signal from the other of said coil assemblies, and determining a position of said primary non ferromagnetic coil assembly relative to said first and second stationary coil assemblies from said induced signal, said determining being capable of a determination on the order of a micron resolution or better, wherein said electronics portion includes a driving circuit that produces a drive signal to said primary non ferromagnetic coil assembly; and a receiving circuit including a differential amplifier that receives an induced output from said first and second stationary coil assemblies; and further includes a low pass filter at one input, and receiving an output of said differential amplifier at another input, and multiplying said one input and said another input to produce a synchronous output.