Means for preventing reset wind-up in electronic control apparatus

Claim 1

ELECTRONIC PROCESS CONTROL APPARATUS OF THE PROPORTIONING TYPE ADAPTED TO RECEIVE AN ELECTRICAL MEASUREMENT SIGNAL CORRESPONDING TO A PROCESS CONDITION TO BE CONTROLLED, AND INCLUDING MEANS TO DEVELOP A CORRESPONDING ELECTRICAL OUTPUT SIGNAL FOR OPERATING A DEVICE ADAPTED TO INFLUENCE SAID PROCESS CONDITION; SAID CONTROL APPARATUS COMPRISING AN ELECTRICAL AMPLIFIER RESPONSIVE TO SAID MEASUREMENT SIGNAL AND INCLUDING AN OUTPUT CIRCUIT TO DEVELOP AN OUTPUT SIGNAL FOR TRANSMISSION TO SAID DEVICE, CIRCUIT MEANS INCLUDING A CAPACITIVE ELEMENT COUPLED TO THE INPUT OF SAID AMPLIFIER FOR INTRODUCING RESET ACTION IN SAID OUTPUT SIGNALS, AND A RESET CONTROL CIRCUIT INCLUDING MEANS RESPONSIVE TO SAID OUTPUT SIGNAL AND COUPLED TO SAID CAPACITOR TO PROPORTIONATELY ADJUST THE CHARGE THEREON SO AS TO TEND TO MAINTAIN SAID OUTPUT SIGNAL AT A PRESELECTED LIMITING VALUE AND TO ADJUST THE INPUT SIGNAL FOR SAID AMPLIFIER SO THAT IT REMAINS WITHIN THE NORMAL OPERATING RANGE OF SAID AMPLIFIER WHILE SAID PROCESS CONDITION VARIES BEYOND THE FULL-SCALE OPERATING RANGE OF THE CONTROL APPARATUS.