Position encoding apparatus

Claim 1

POSITION INDICATING APPARATUS FOR INDICATING THE POSITION OF ONE STRUCTURE RELATIVE TO ANOTHER COMPRISING FIRST AND SECOND MEMBERS ADAPTED TO BE MOVED RELATIVE TO ONE ANOTHER IN ACCORDANCE WITH THE POSITIONS OF SAID STRUCTURES, EACH MEMBER HAVING A SET OF EQUALLY SPACED INDICIA THEREON, ORE SET HAVING ONE MORE INDICIUM PER UNIT LENGTH THAN THE OTHER SET, A COOPERATING MEMBER DISPOSED ADJACENT SAID FIRST AND SECOND MEMBERS, SAID COOPERATING MEMBER INCLUDING TWO SETS OF EQUALLY SPACED COOPERATING ELEMENTS, EACH SET OF COOPERATING ELEMENTS BEING POSITIONED ADJACENT A CORRESPONDING INDICIA SET, EACH SET OF COOPERATING ELEMENTS HAVING THE SAME NUMBER OF ELEMENTS AS THE CORRESPONDING INDICIA SET ON SAID FIRST AND SECOND MEMBERS, MEANS TO DRIVE SAID COOPERATING MEMBER SO THAT ITS COOPERATING ELEMENTS MOVE PAST THE SETS OF INDICIA ON SAID FIRST AND SECOND MEANS IN A CYCLICAL MANNER, SIGNAL PRODUCING MEANS ASSOCIATED WITH EACH SET OF INDICIA AND ITS CORRESPONDING SET OF COOPERATING ELEMENTS INCLUDING MEANS TO PRODUCE A COINCIDENCE SIGNAL UPON THE SIMULTANEOUS SENSING OF POSITIONS OF COINCIDENCE BETWEEN THE INDICIA IN EACH SET AND THEIR COOPERATING ELEMENTS, MEANS TO PRODUCE A SERIES OF COUNT SIGNALS DURING EACH CYCLE OF SAID COOPERATING MEMBER, AND MEANS RESPONSIVE TO SAID COUNT SIGNALS AND SAID COINCIDENCE SIGNALS TO PRODUCE A VERNIER INDICATION OF THE RELATIVE POSITIONS OF SAID STRUCTURES.