Rotatable magnetic field-sensing solid-state switch apparatus

Claim 1

A solid-state rotary switch apparatus, comprising: a magnetic member rotatable in a plane; first and second magnetic field sensors each having a sensor axis disposed substantially perpendicular to one another and in another plane adjacent to the plane of magnetic member rotation; each sensor providing an output signal of magnitude proportional to the angle of said magnetic member with respect to the sensor axis thereof; and means responsive to the outputs of said sensors for providing digital data indicating that one of a preselected plurality P of angular rotational positions of said magnetic member, with respect to a rotational reference, to which a selected pole of said member is presently rotated, said digital data providing means including: first and second differential-input, differential-output amplifiers each receiving the output signal of one of said sensors; a resistance element chain connected between the differential outputs of each of said amplifiers; a plurality of two-input comparators, the inputs of each comparator being connected to terminals of said resistance chain in preselected manner to cause each comparator output to be enabled when said selected pole of said magnetic member is at different ones of π radians of rotation from said reference line; a plurality of two-input exclusive-OR-gates, each gate having each input thereof connected to a different one of two adjacent ones of said comparators for enabling a gate output only when said magnetic member is positioned at diametrically-opposed different ones of the plurality of possible rotational positions of said magnetic member; a plurality N of data output lines, where the number P of possible rotational positions of said member, and therefore of said switch apparatus, is given by P=2 N ; and a diode array for connecting the outputs of said gates to the (N-1) least significant output lines, with the output of a selected one of said comparators being connected directly to the most significant bit data output line, to provide an N-bit digitally-coded output of that one of 2 N positions of said magnetic member with respect to said reference line.