Servo system and comparator

Claim 1

IN A SERVO SYSTEM, A FIRST (M+N)-STAGE DIGITAL COUNTER; A SECOND (M+N)-STAGE DIGITAL COUNTER; A COMPARATOR HAVING A DIGITAL SECTION AND AN ANALOGUE SECTION, THE DIGITAL SECTION INCLUDING MEANS FOR COMPARING THE CONTENTS OF THE M STAGES OF SAID FIRST AND SECOND COUNTERS AND GENERATING A FIRST OUTPUT SIGNAL OF PREDETERMINED MAGNITUDE WHEN THE CONTENTS OF THE M STAGES OF SAID FIRST DIGITAL COUNTER IS GREATER THAN THE CONTENTS OF THE M STAGES OF SAID SECOND DIGITAL COUNTER, AND GENERATING A SECOND OUTPUT SIGNAL OF THE SAME PREDETERMINED MAGNITUDE WHEN THE CONTENTS OF THE M STAGES OF SAID SECOND DIGITAL COUNTER IS GREATER THAN THE CONTENTS OF THE M STAGES OF SAID FIRST DIGITAL COUNTER, AND THE ANALOGUE COMPARATOR SECTION INCLUDING MEANS FOR CONVERTING THE CONTENTS OF THE STAGES SAID FIRST DIGITAL COUNTER INTO A THIRD OUTPUT SIGNAL OF MAGNITUDE PROPORTIONAL TO THE CONTENTS OF THE THE N STAGES THEREOF, MEANS FOR CONVERTING THE CONTENTS OF THE N STAGES OF SAID SECOND DIGITAL COUNTER INTO A FOURTH OUTPUT SIGNAL OF MAGNITUDE PROPORTIONAL TO THE CONTENTS OF THE N STAGES THREROF, THE THIRD AND FOURTH OUTPUT SIGNALS HAVING A PREDETERMINED MAXIMUM MAGNITUDE SMALLER THAN THE PREDETERMINED MAGNITUDES OF THE FIRST AND SECOND OUTPUT SIGNALS, AND MEANS FOR COMBINING THE FIRST AND SECOND OUTPUT SIGNALS RESPECTIVELY WITH THE THIRD AND FOURTH OUTPUT SIGNALS; AND A DIFFERENTIAL OPERATIONAL AMPLIFIER HAVING THE COMBINED OUTPUT SIGNALS APPLIED THERETO A PROVIDE AN OUTPUT SIGNAL OF ONE POLARITY WHEN THE CONTENTS OF SAID FIRST DIGITAL COUNTER IS GREATER THAN THAT OF SAID SECOND DIGITAL COUNTER AND OF REVERSED POLARITY WHEN SUCH CONDITION IS REVERSED, THE OUTPUT SIGNAL OF SAID DIFFERNTIAL OPERATIONAL AMPLIFIER BEING PROPORTIONAL TO THE DIFFERENCE IN MAGNITUDE OF THE COMBINED SIGNAL PAIRS.