Apparatus for producing signals indicative of relative position

Claim 1

APPARATUS FOR PROVIDING ELECTRICAL SIGNALS INDICATIVE OF POSITIONAL RELATIONSHIP, COMPRISING TWO RELATIVELY MOVABLE MEMBERS OF WHICH THE FIRST HAS AN ELECTRICALLY CONDUCTIVE SURFACE HAVING A TOOTHED PROFILE AND THE SECOND HAS A PLURALITY OF EQUALLY SPACED CONDUCTIVE STRIPS WHICH, BEING DISPOSED IN SENSIBLE CAPACITIVE PROXIMITY TO THE TEETH OF THE FIRST MEMBER AND EXTENDING TRANSVERSELY OF THE DIRECTION OF RELATIVE MOVEMENT BETWEEN THE TWO MEMBERS, ARE CONNECTED TOGETHER INTO AT LEAST THREE SETS AND HAVE A CENTRE-TO-CENTRE SPACING BETWEEN ADJACENT STRIPS WHICH IS RELATED TO THE TOOTH PITCH BY THE EXPRESSION M=PN$1 WHERE N IS THE NUMBER OF SETS OF STRIPS, GREATER THAN 2, P IS AN ARBITRARY NUMBER WHICH CAN BE ZERO, AND M IS AN INTEGRAL NUMBER OF TOOTH PITCHES CORRESPONDING TO THE CENTRE-TO-CENTRE SPACING OF SUCCESSIVE STRIPS OF THE SAME SET, EACH SET BEING CONSTITUTED BY STRIPS WHICH HAVE A SIMILAR POSITIONAL RELATIONSHIP TO RESPECTIVE TEETH OF THE FIRST MEMBER AND THE SEVERAL SETS BEING CONNECTED TO A TRANSFORMER ARRANGEMENT FOR CORRELATING IN A POSITIONAL OUTPUT SIGNAL THEREFROM THE CYCLIC VARATIONS OF CAPACITANCE WHICH WILL OCCUR BETWEEN THE TOOTHED MEMBER AND THE SEVERAL SETS OF STRIPS DURING RELATIVE MOVEMENT BETWEEN THE TWO MEMBERS.