Motor synchronizing system utilizing reversible counter and logic means

Claim 1

IN A SYSTEM FOR OPERATING A SYNCHRONOUS AC SLAVE MOTOR IN SUBSTANTIAL SYNCHRONISM WITH AN AC MASTER MOTOR, THE COMBINATION COMPRISING: (A) MEANS FOR GENERATING A PATTERN OF PERIODIC MASTER SYNCHRONIZING PULSES INDICATIVE OF THE ROTATIONAL POSITION AND SPEED OF SAID MASTER MOTOR; (B) MEANS FOR GENERATING A PATTERN OF PERIODIC SLAVE SYNCHRONIZING SIGNALS INDICATIVE OF THE ROTATIONAL POSITION AND SPACED OF SAID SLAVE MOTOR; (C) MEANS INCLUDING A SOURCE OF VARIABLE FREQUENCY AC POWER FOR SELECTIVELY CONTROLLING THE SPEED OF SAID SLAVE MOTOR; (D) DIGITAL-TO-ANALOG CONVERTER MEANS COUPLED TO SAID VARIABLE AC POWER SOURCE FOR SELECTIVELY DEVELOPING FREQUENCY DETERMINING SIGNALS FOR CONTROLLING THE FREQUENCY OF SAID VARIABLE AC POWER SOURCE; (E) REVERSIBLE COUNTER MEANS HAVING TWO INPUTS FOR CAUSING SAID COUNTER MEANS TO ENTER A COUNT IN EITHER A FORWARD OR A REVERSE DIRECTION IN RESPONSE TO COUNT SIGNALS AT ONE OR THE OTHER OF SAID INPUTS, RESPECTIVELY; (F) CIRCUIT MEANS FOR COUPLING A SIGNAL REPRESENTATIVE OF THE COUNT IN SAID REVERSIBLE COUNTER MEANS TO SAID DIGITAL-TO-ANALOG CONVERTER MEANS; AND, (G) CONTROL MEANS RESPONSIVE TO SAID MASTER AND SLAVE SYNCHRONIZING PULSES FOR GENERATING AT EITHER SAID ONE OR SAID OTHER OF SAID INPUTS OF SAID REVERSIBLE COUNTER MEANS, DEPENDING UPON THE SENSE OF PHASE DIFFERENCE BETWEEN SAID MASTER AND SAID SLAVE MOTORS, COUNT SIGNALS INDICATIVE OF THE PHASE DIFFERENCE BETWEEN SAID MASTER AND SLAVE MOTORS.