Planar coil apparatus employing a stationary and a movable board

Abstract

A planar coil apparatus is disclosed for providing an output signal indicative of a movement between at least a first and a second position. A first stationary planar member has disposed on a surface, a first flat coil configuration which is emplaced thereon by a printed circuit or similar technique. Located adjacent to this coil on the board is a second coil of similar configuration. A drive signal such as that obtained from an AC or pulse source is applied to the input terminals of one of the coils which constitutes the drive coil. A second planar board is positioned relatively congruent and above the first board and has located thereon a closed coil configuration which constitutes a closed coil loop. As this movable board is brought into proximity with the stationary board, magnetic flux is coupled via the loop from the drive coil to the second coil which serves as the sense coil. By monitoring the output of the sense coil, an AC signal can be detected when the movable board is within a predetermined range of distances from the stationary board. The detection of the AC signal indicates a change of position or state. Various other arrangements employ a movable board configuration containing a plurality of coils in conjunction with a stationary board configuration containing predetermined drive and sense coils to represent various coding patterns.

Dependencies are inferred from the claim text.