Inductive multi-speed resolver

Claim 1

DISPLACEMENT MEASURING APPARATUS COMPRISING A CLOSED MAGNETIC STRUCTURE DEFINING A PLURALITY OF SPACED SALIENT MAGNETIC POLES EXTENDING TOWARD A TRANSVERSELY OPPOSITE PORTION OF THE STRUCTURE BUT SEPARATED THEREFROM BY AN AIR GAP, A BODY OF MAGNETIC MATERIAL ADAPTED FOR DISPLACEMENT THROUGH THE GAPS BETWEEN THE POLES AND THE TRANSVERSELY OPPOSITE PORTION, A PRIMARY AND A SECONDARY WINDING DISPOSED ON EACH OF THE POLES AND BEING MAGNETICALLY LINKED TO A DEGREE DEPENDING UPON THE ORIENTATION OF THE DISPLACEABLE BODY IN THE GAP ADJACENT THE POLE, MEANS FOR EXCITING EACH OF THE PRIMARY WINDINGS WITH A VOLTAGE WHICH IS PHASE-SHIFTED FROM THE VOLTAGE IN THE ADJACENT PRIMARY BY A PREDETERMINED ELECTRICAL ANGLE, AND MEANS CONNECTING THE SECONDARY WINDING MEANS IN SERIES RELATION TO PROVIDE AN OUTPUT VOLTAGE WHICH VARIES IN PHASE ACCORDING TO THE DISPLACEMENT OF SAID BODY RELATIVE TO THE POLES.