Maximum error signal detector for a servo control and a circuit override responsive thereto

Claim 1

IN A PROGRAM CONTROLLED MACHINE HAVING A PLURALITY OF MOVABLE MEMBERS, THE POSITION OF EACH MEMBER BEING CONTROLLED BY A SERVO UNIT RESPONSIVE TO ELECTRICAL SIGNALS, AND A PLURALITY OF CONTROL UNITS FOR FURNISHING THE ELECTRICAL SIGNALS TO SAID SERVO UNITS, EACH SERVO UNIT BEING RESPONSIVE TO SIGNALS FROM A DIFFERENT ONE OF SAID CONTROL UNITS, THE COMBINATION COMPRISING A PLURALITY OF THRESHOLD MEANS FOR SENSING SAID ELECTRICAL SIGNALS TO PRODUCE AN OUTPUT SIGNAL IF ANY SUCH SIGNAL EXCEEDS A PREDETERMINED THRESHOLD LEVEL, EACH SAID THRESHOLD MEANS SENSING A DIFFERENT ONE OF SAID SIGNALS, EACH SAID THRESHOLD MEANS COMPRISING A NORMALLY NONCONDUCTING TRANSISTOR HAVING A COLLECTOR ELECTRODE AND A CONTROL ELECTRODE; MEANS FOR APPLYING ONE OF SAID ELECTRICAL SIGNALS TO THE CONTROL ELECTRODE OF EACH OF SAID TRANSISTORS; MEANS CONNECTING THE COLLECTOR ELECTRODES OF ALL SAID TRANSISTORS IN COMMON; IMPEDANCE MEANS CONNECTED BETWEEN A SOURCE OF POTENTIAL AND SAID COLLECTOR TERMINALS, WHEREBY SAID OUTPUT SIGNAL IS PRODUCED AT SAID IMPEDANCE MEANS WHEN ANY OF SAID TRANSISTORS IS DRIVEN INTO CONDUCTION BY ITS RESPECTIVE ELECTRICAL SIGNAL; AND INHIBITING MEANS CONNECTED TO THE COMMON CONNECTION OF SAID COLLECTOR ELECTRODES, SAID INHIBITING MEANS BEING OPERATIVE TO INHIBIT FURTHER OPERATION OF SAID PROGRAM CONTROLLED MACHINE IN RESPONSE TO CONDUCTION OF ANY OF SAID TRANSISTORS.