Capacitive encoder device

Claim 1

A CAPACITIVE ENCODER INCLUDING IN COMBINATION A DISK OF INSULATING MATERIAL, A COATING OF CONDUCTIVE MATERIAL CARRIED BY SAID DISK ON ONE SIDE THEREOF AND FORMING A COMMON CAPACITOR PLATE, A PLURALITY OF DISCRETE CONDUCTIVELY ISOLATED AREAS OF CONDUCTIVE MATERIAL ON THE OTHER SIDE OF SAID DISK, GROUPS OF SAID AREAS BEING DISPOSED ON THE LOCI OF REPRESENTIVE CONCENTRIC CIRCLES TO FORM A CODED PATTERN, RESPECTIVE SECOND CAPACITOR PLATES, MEANS MOUNTING SAID SECOND CAPACITOR PLATES IN SPACED RELATIONSHIP TO SAID DISK ADJACENT THE OTHER SIDE OF SAID DISK AND IN CONDUCTIVELY SPACED RELATIONSHIP TO SAID AREAS OF CONDUCTIVE MATERIAL TO FORM CAPACITORS WITH SAID COMMON PLATE, SAID SECOND CAPACITOR PLATES BEING DISPOSED ON SAID MOUNTING MEANS AT LOCATIONS AT WHICH THEY REGISTER WITH THE RESPECTIVE CIRCLES, MEANS FOR MOVING SAID DISK AND SAID SECOND CAPACITOR PLATES RELATIVE TO EACH OTHER TO VARY THE CAPACITANCE BETWEEN SAID SECOND PLATES AND SAID COMMON PLATE AND MEANS FOR DERIVING RESPECTIVELY ELECTRICAL SIGNALS IN RESPONSE TO SAID CAPACITANCE VARIATION.