Servo system having high resolution d/a

Claim 1

A HIGH RESOLUTION DIGITAL TO ANALOG CONVERTER COMPRISING: A FIRST COUNTER CIRCUIT FOR RECEIVING DIGITAL INPUT SIGNALS AND FOR PERIODICALLY GENERATING AN OVERFLOW SIGNAL AFTER A PREDETERMINED NUMBER OF DIGITAL SIGNALS HAVE BEEN RECEIVED; A CLOCK FOR GENERATING A PLURALITY OF TIMING PULSES; A PREDETERMINED NUMBER OF CLOCK CYCLES DEFINING A SAMPLING PERIOD; A COUNT CONTROL CIRCUIT OPERATIVELY CONNECTED TO THE FIRST COUNTER CIRCUIT AND THE CLOCK FOR RECEIVING A FIXED NUMBER OF TIMING PULSES FROM THE CLOCK DURING THE SAMPLING PERIOD AND THE OVERFLOW SIGNAL FROM THE FIRST COUNTER AND GENERATING A COUNT FOR EVERY EACH OF THE FIXED NUMBER OF TIMING PULSES AND THE OVERFLOW SIGNAL; A SECOND COUNTER OPERATIVELY CONNECTED TO THE COUNT CONTROL CIRCUIT FOR RECEIVING COUNTS FROM THE COUNT CONTROL CIRCUIT; A FIRST STORAGE DEVICE FOR RETAINING A NUMBER DERIVED FROM THE COUNTER AT A PREDETERMINED TIME IN THE SAMPLING PERIOD; A SECOND STORAGE DEVICE FOR RETAINING THE NUMBER DERIVED FROM THE COUNTER AS INCREMENTED BY A FIXED NUMBER; A DIGITAL TO ANALOG CONVERTER ADAPTED TO CONVERT A DIGITAL SIGNAL TO AN ANALOG SIGNAL; AND A LATCH CONTROL CIRCUIT OPERATIVELY CONNECTED TO THE FIRST COUNTER AND THE FIRST AND SECOND STORAGE DEVICES FOR SELECTIVELY APPLYING THE RESPECTIVE NUMBER IN THE STORAGE DEVICES TO THE DIGITAL TO ANALOG CONVERTER IN ACCORDANCE WITH THE OCCURRENCE OF THE OVERFLOW SIGNAL TO THEREBY VARY THE AVERAGE ANALOG SIGNAL WITH THE RATE OF RECEPTION OF THE DIGITAL INPUT SIGNALS.