Digital fine and coarse servo motor control system

Claim 1

A DIGITAL SYSTEM FOR CONTROLLING THE POSITION ALONG A GIVEN PATH OF A MOVABLE STRUCTURE MOVABLY MOUNTED ON A FIXED STRUCTURE, COMPRISING DRIVE MEANS COUPLED TO SAID MOVABLE STRUCTURE FOR DISPLACING IT; DETECTOR MEANS MOUNTED ON SAID TWO STRUCTURES FOR DETECTING POSITIONAL VARIATION OF SAID MOVABLE STRUCTURE ALONG SAID PATH, SAID DETECTOR MEANS COMPRISING SCALE MEANS AFFIXED TO ONE OF SAID STRUCTURES AND AN OPTICAL DETECTING ELEMENT MOVABLY MOUNTED ON THE OTHER OF SAID STRUCTURES IN OPERATIVE PROXIMITY WITH SAID SCALE MEANS; DATUM SETTING MEANS HAVING A FIRST PORTION SELECTIVELY ADJUSTABLE FOR SETTING THE MAJOR AMOUNT OF A DESIRED POSITIONAL DATUM VALUE AND HAVING A SECOND PORTION SELECTIVELY ADJUSTABLE FOR SETTING THE RESIDUAL AMOUNT OF SAID DATUS VALUE; PRESETTING CONTROL MEANS COUPLED TO SAID OPTICAL DETECTING ELEMENT FOR MOVING SAID OPTICAL DETECTING ELEMENT RELATIVE TO SAID STRUCTURE IN ACCORDANCE WITH SAID RESIDUAL AMOUNT, SAID PRESETTING CONTROL MEANS COMPRISING FIRST REGISTER MEANS HAVING AN OUTPUT AND A CONTENT EQUAL TO THAT OF THE SECOND PORTION OF SAID DATUM SETTING MEANS, A SERVOMOTOR COUPLED TO SAID OPTICAL DETECTING ELEMENT FOR MOVING SAID OPTICAL DETECTING ELEMENT ALONG SAID GIVEN PATH, A PULSE GENERATOR COUPLED TO SAID OPTICAL DETECTING ELEMENT FOR PROVIDING PULSES CORRESPONDING IN NUMBER TO THE DISPLACEMENT OF SAID OPTICAL DETECTING ELEMENT, FIRST COUNTER MEANS HAVING AN OUTPUT AND AN INPUT CONNECTED TO SAID PULSE GENERATOR FOR COUNTING PULSES GENERATED BY SAID PULSE GENERATOR, FIRST COMPARATOR MEANS HAVING AN OUTPUT CONNECTED TO SAID SERVOMOTOR, AN INPUT CONNECTED TO THE OUTPUT OF SAID FIRST COUNTER MEANS AND AN INPUT CONNECTED TO THE OUTPUT OF SAID FIRST REGISTER MEANS FOR COMPARING THE CONTENTS OF SAID FIRST REGISTER MEANS AND SAID FIRST COUNTER MEANS FOR ENERGIZING SAID SERVO-MOTOR UNTIL COINCIDENCE OF THE CONTENTS OF SAID FIRST REGISTER MEANS AND FIRST COUNTER MEANS; AND DRIVE CONTROL MEANS COUPLED TO SAID DRIVE MEANS, SAID DRIVE CONTROL MEANS COMPRISING SECOND REGISTER MEANS HAVING AN OUTPUT AND A CONTENT EQUAL TO THAT OF THE FIRST PORTION OF SAID DATUM SETTING MEANS, SECOND COUNTER MEANS HAVING AN OUTPUT AND AN INPUT CONNECTED TO SAID DETECTOR MEANS FOR COUNTING PULSES GENERATED BY SAID DETECTOR MEANS, SECOND COMPARATOR MEANS HAVING AN OUTPUT CONNECTED TO SAID DRIVE MEANS, AN INPUT CONNECTED TO THE OUTPUT OF SAID SECOND COUNTER MEANS AND AN INPUT CONNECTED TO THE OUTPUT OF SAID SECOND REGISTER MEANS FOR COMPARING THE CONTENTS OF SAID SECOND REGISTER MEANS AND SAID SECOND COUNTER MEANS AND FOR ENERGIZING SAID DRIVE MEANS UNTIL COINCIDENCE OF THE CONTENTS OF SAID SECOND REGISTER MEANS AND SECOND COUNTER MEANS.