High efficiency instrument servo amplifier for microminiaturization

Claim 1

A VOLTAGE CONTROLLED ELECTRONIC SWITCHING MEANS FOR SELECTIVELY DRIVING BOTH PHASES OF A SPLIT PHASE INDUCTION MOTOR COMPRISING, A SOURCE OF REFERENCE MOTOR DRIVE SIGNAL HAVING A PREDETERMINED FREQUENCY; MEANS FOR DEVELOPING FIRST AND SECOND CONTROL VOLTAGES OF OPPOSED PHASE WITH ONE OF SAID CONTROL VOLTAGES BEING 90* OUT OF PHASE WITH SAID REFERENCE SIGNAL; MEANS FOR COLLECTIVELY REVERSING THE RESPECTIVE PHASES OF SAID CONTROL VOLTAGES; SAID SERVO MOTOR HAVING FIRST AND SECOND FIELD WINDINGS WITH FIRST TERMINALS THEREOF CONNECTED IN COMMON TO A FIRST JUNCTION, A PHASE SHIFTING CAPACITOR CONNECTED BETWEEN THE OTHER TERMINALS OF SAID MOTOR FIELD WINDINGS; FIRST AND SECOND VOLTAGE CONTROLLED RECTIFIERS EACH HAVING A CATHODE, AN ANODE, AND A CONTROL ELECTRODE; THE ANODES OF SAID FIRST AND SECOND CONTROLLED RECTIFIERS BEING RESPECTIVELY CONNECTED THROUGH FIRST AND SECOND CAPACITORS TO SAID OTHER TERMINALS OF SAID MOTOR FIELD WINDINGS, THE CONTROL ELECTRODES OF SAID FIRST AND SECOND CONTROLLED RECTIFIERS BEING RESPECTIVELY CONNECTED TO SAID FIRST AND SECOND CONTROL VOLTAGES, FIRST AND SECOND UNILATERAL CONDUCTION DEVICES RESPECTIVELY SHUNTING EACH OF SAID FIRST AND SECOND CONTROLLED RECTIFIERS AND BEING OPPOSITELY POLARIZED WITH RESPECT THERETO, THE CATHODES OF EACH OF SAID CONTROLLED RECTIFIERS CONNECTED IN COMMON TO A SECOND JUNCTION, SAID SOURCE OF REFERENCE MOTOR DRIVE SIGNAL BEING CONNECTED BETWEEN SAID FIRST AND SECOND JUNCTIONS, THIRD AND FOURTH UNILATERAL CONDUCTION DEVICES, EACH OF SAID FIRST AND SECOND CONTROL VOLTAGES CONNECTED SERIALLY WITH ONE OF SAID THIRD AND FOURTH UNILATERAL CONDUCTION DEVICES AND ONE OF SAID FIRST AND SECOND VOLTAGE CONTROLLED RECTIFIERS RESPECTIVELY TO SAID SECOND JUNCTION, EACH OF SAID THIRD AND FOURTH UNILATERAL CONDUCTION DEVICES BEING LIKE POLARIZED WITH RESPECT TO THE ASSOCIATED ONE OF SAID FIRST AND SECOND CONTROLLED RECTIFIERS AND BEING CONNECTED TO THE ONE OF SAID FIRST AND SECOND CONTROL VOLTAGES WHICH IS EFFECTIVE IN GATING THE DISASSOCIATED ONE OF SAID FIRST AND SECOND VOLTAGE CONTROLLED RECTIFIERS, WHEREBY IN THE ABSENCE OF SAID CONTROL VOLTAGES SAID MOTOR IS UNENERGIZED AND IN THE PRESENCE OF SAID CONTROL VOLTAGES MOTOR ROTATION IS EFFECTED IN A DIRECTION DEFINED BY THE RESPECTIVE PHASES OF SAID CONTROL VOLTAGES WITH RESPECT TO SAID REFERENCE MOTOR DRIVE SIGNAL.