Rotary position sensors employing planar coils

Claim 1

A rotary displacement transducer, comprising: (a) a first planar member having disposed on a surface thereof four flat coil configurations each occupying a predetermined area on said surface and each located at 90° intervals with respect to one another and defining four quadrants, (b) a second planar member having disposed thereon four additional flat coil configurations each one aligned with and complimentary to an associated coil on said first planar member when said second planar member is positioned apart from said first member and relatively parallel to and facing said first member to form a space therebetween, whereby any magnetic field induced in one of said members can couple to the other, (c) a rotatable plate of a circular configuration and positioned in the space between said members and located to rotate about an axis eccentric to the center of said plate to cause said plate to fully cover only one of said coils and to partially cover two other coils as it rotates and fabricated from a material sufficient to block said magnetic field, said plate to provide, when rotated, magnetic field coupling between two opposite coils having an output indicative of a sinusoidal output with the coupling between the other two opposite coils indicative of a cosine output, whereby any two of said coils can provide quadrant identification for output signals taken from said two other coils.