Stepper motor servo amplifier

Claim 1

A DEVICE FOR DRIVING A STEPPER MOTOR WHEN AN APPLIED D.C. ANALOG SIGNAL EXCEEDS A PREDETERMINED RANGE, COMPRISING A PAIR OF TRIGGER CIRCUITS CONNECTED TO RECEIVE THE SIGNAL, ONE CIRCUIT BEING TRIGGERED WHEN THE SIGNAL EXCEEDS ONE LIMIT OF THE RANGE, AND THE OTHER BEING TRIGGERED WHEN THE D.C. SIGNAL EXCEEDS THE OTHER LIMIT OF THE RANGE, BOTH TRIGGER CIRCUITS PROVIDING A FIRST LEVEL OUTPUT SIGNAL WHEN IN AN UNTRIGGERED STATE HAND A SECOND LEVEL OUTPUT SIGNAL WHEN IN A TRIGGERED STATE, POWER AMPLIFIER MEANS CONNECTING A SOURCE OF POTENTIAL TO THE STEPPER MOTOR AND CONNECTED TO THE TRIGGER CIRCUIT AND CONTROLLED BY THE OUTPUT LEVEL SIGNAL THEREFROM FOR PROVIDING POWER TO THE STEPPER MOTOR WHEN EITHER CIRCUIT IS TRIGGERED AND THE SECOND LEVEL OUTPUT SIGNAL IS APPLIED THERETO, A DIRECTION ROTATION CONTROL NETWORK CONNECTED TO THE TRIGGER CIRCUITS FOR RECEIVING THE OUTPUTS THEREFROM TO ROTATE THE STEPPER MOTOR IN ONE DIRECTION WHEN A SECOND LEVEL OUTPUT SIGNAL IS RECEIVED FROM ONE TRIGGER CIRCUIT AND IN THE OTHER DIRECTION WHEN A SECOND LEVEL OUTPUT SIGNAL IS RECEIVED FROM THE OTHER TRIGGER CIRCUIT.