Phase modulated positioning servo-system

Claim 1

IN AN ELECTROMECHANICAL DEVICE FOR CONTROLLING THE RELATIVE POSITION OF ONE MEMBER WITH RESPECT TO ANOTHER MEMBER, IN COMBINATION, AN ELONGATED FIRST MEMBER COMPOSED PREDOMINANTLY OF MAGNETIC MATERIAL CAPABLE OF PERMANENT MAGNETIZATION AND PROVIDED WITH A LONGITUDINALLY EXTENDING SERIES OF PERMANENTLY MAGNETIZED SURFACE PORTIONS OF ALTERNATELY OPPOSED POLARITY AND OF UNIFORM UNIT LENGTHS; A SECOND MEMBER COMPRISING A ROTARY CYLINDRICAL BODY HAVING AN AXIS AND BEING COMPOSED OF TWO PORTIONS MADE OF MAGNETICALLY PERMEABLE MATERIAL AND A NON-MAGNETIC SPACER SEPARATING SAID PERMEABLE PORTIONS, EACH OF SAID PERMEABLE PORTIONS BEING PROVIDED ON ITS CYLINDRICAL SURFACE WITH A CONTINUOUS HELICAL RIDGE WITH A PITCH EQUAL TO TWO OF SAID UNIT LENGTHS OF SAID MAGNETIZED SURFACE PORTIONS OF SAID FIRST MEMBER, THE HELICAL RIDGE OF ONE OF SAID PORTIONS BEING AXIALLY OFFSET AGAINST THE HELICAL RIDGE OF THE OTHER PORTION AN AMOUNT EQUAL N.1/2P WHEREIN P IS SAID PITCH AND N IS AN UNEVEN NUMBER INCLUDING "1", SAID ROTARY CYLINDRICAL BODY BEING MOUNTED WITH ITS AXIS EXTENDING PARALLEL WITH SAID SERIES OF MAGNETIZED SURFACE PORTIONS OF SAID FIRST MEMBER, SAID SURFACE PORTIONS BEING SPACED A SHORT DISTANCE FROM THE CIRCUMFERENCE OF SAID HELICAL RIDGES; YOKE MEANS OF MAGNETICALLY PERMEABLE MATERIAL ARRANGED TO ESTABLISH A MAGNETIC CIRCUIT BETWEEN SAID PERMEABLE PORTIONS OF SAID ROTARY BODY; COIL MEANS MOUNTED ON SAID YOKE MEANS FOR GENERATING AN ALTERNATING VOLTAGE WHEN SAID ROTARY BODY IS ROTATED; DRIVE MEANS FOR ROTATING SAID ROTARY BODY AT A PREDETERMINED SPEED; AND OPERATING MEANS FOR MOVING ONE OF SAID FIRST AND SECOND MEMBERS RELATIVELY TO EACH OTHER IN DIRECTION OF SAID AXIS WHILE SAID ROTARY BODY IS BEING ROTATED, WHEREBY THE PHASE POSITION OF SAID ALTERNATING VOLTAGE IS VARIED IN DIRECT PROPORTION TO THE AMOUNT OF MOVEMENT OF ONE OF SAID FIRST AND SECOND MEMBERS RELATIVE TO EACH OTHER.