Logarithmic digital process controller

Claim 1

A PROCESS CONTROLLER COMPRISING A PLURALITY OF INPUT SIGNAL MEANS ARRANGED TO BE CONNECTED TO RESPECTIVE SIGNAL SOURCES REPRESENTATIVE OF MONITORED PROCESS VARIABLES, SAID INPUT SIGNAL MEANS INCLUDING ERROR MEANS EACH OPERATIVE TO PROVIDE AN INDICATION OF A DEVIATION OF A CORRESPONDING VARIABLE FROM A SETPOINT, SWITCHING MEANS OPERATIVE TO SEQUENTIALLY SELECT SAID INDICATION FROM EACH OF SAID ERROR MEANS, ANALOG TO DIGITAL CONVERTING MEANS OPERATIVE TO CONVERT EACH SELECTED INDICATION TO A DIGITAL SIGNAL, ENCODING MEANS OPERATIVE TO ENCODE EACH DIGITAL SIGNAL TO A DIGITAL REPRESENTATION OF AN APPROXIMATE LOGARITHM THEREOF, DIGITAL COMPUTER MEANS RESPONSIVE TO AN OUTPUT SIGNAL FROM SAID ENCODING MEANS AND OPERATIVE TO COMPUTE A CONTROL SIGNAL FOR EACH MONITORED VARIABLE AND MEANS FOR DISTRIBUTING SAID CONTROL SIGNAL FOR EACH VARIABLE TO A PROCESS CONTROL OPERATIVE TO AFFECT THE CORRESPONDING MONITORED VARIABLE, SAID LAST MENTIONED MEANS INCLUDING A MEMORY MEANS OPERATIVE TO STORE SAID CONTROL SIGNAL FOR EACH VARIABLE, AND READOUT MEANS OPERATIVE TO SEQUENTIALLY AFFECT EACH PROCESS CONTROL IN RESPONSE TO A RESPECTIVE STORED CONTROL SIGNAL TO REDUCE SAID DEVIATION.