Apparatus for measuring angular displacement of a rotatable member by electronic means

Claim 1

IN AN APPARATUS FOR MEASURING ANGULAR DEVIATIONS IN A TRANSVERSE PLANE OF A ROTATABLE MEMBER FROM A REFERENCE POSITION DETERMINED BY A SECOND ROTATABLE MEMBER, IN COMBINATION, SIGNAL CARRIED MEANS MOUNTED ON A ROTATABLE MEMBER AND PROVIDED WITH A FIRST REPRODUCEABLE SIGNAL RECORD DETERMINING A FIRST FREQUENCY SIGNAL UPON ROTATION OF SAID ROTATABLE MEMBER AT A PREDETERMINED SPEED, A SECOND REPRODUCEABLE SIGNAL RECORD DETERMINING A SECOND FREQUENCY SIGNAL UPON ROTATION OF SAID MEMBER AT SAID SPEED, SAID SECOND FREQUENCY DIFFEREING BY ONE CYCLE FROM SAID FIRST FREQUENCY, AND A THIRD REPRODUCABLE SIGNAL RECORD DETERMINING A THIRD SIGNAL UPON ROTATION OF SAID MEMBER AT SAID SPEED, SAID THIRD SIGNAL CONSISTING OF SAID IMPULSE FOR REVOLUTION, THE START OF SAID IMPULSE COINCIDING WITH THE START OF ONE OF THE CYCLES OF SAID FIRST SIGNAL; FIRST AND THIRD PICK-UP MEANS MOUNTED STATIONARILY OPPOSITE SAID FIRST AND THIRD SIGNAL RECORDS, RESPECTIVELY, FOR BEING ACTUATED THEREBY AND FOR DELIVERING SAID SIGNALS, RESPECTIVELY; SECOND PICK-UP MEANS MOUNTED ON A SECOND ROTATABLE MEMBER ARRANGED CO-AXIALLY WITH SAID FIRST MEMTIONED ROTATABLE MEMBER, SAID SECOND PICK-UP MEANS BEING LOCATED OPPOSITE SAID SECOND SIGNAL RECORD FOR BEING ACTUATED THEREBY AND FOR DELIVERING SAID SECOND SIGNAL; DRIVE MEANS FOR ROTATING SAID DIRST MENTIONED ROTATABLE MEMBER AT A PREDETERMINED CONSTANT SPEED; TURN MEANS FOR TURNING SAID SECOND ROTATABLE MEMBER FROM A NORMAL REFERENCE POSITION TO ANGULARLY DISPLACED POSITIONS FOR CAUSING, DURING ROTATION OF SAID FIRST MENTIONED ROTATABLE MEMBER A TIME SHIFT BETWEEN SAID FIRST AND SECOND SIGNALS PROPORTIONAL TO THE ANGULAR DEVIATIONS OF THE POSITIONS OF SAID SECOND ROTATABLE MEMBER WITH RESPECT TO SAID REFERENCE POSITION THEREOF; PHASE DETECTOR MEANS IN CIRCUIT WITH SAID FIRST AND SECOND PICK-UP MEANS, RESPECTIVELY, FOR COMPARING THE RESPECTIVE PHASES OF SAID FIRST AND SECOND SIGNALS AND FOR FURNISHING AN IMPULSE WHEN THE PHASE DIFFERENCE IS ZERO; GAGE MEANS IN CIRCUIT WITH SAID FIRST PICK-UP MEANS FOR DELIVERING AT ITS OUTPUT PULSES FURNISHED BY SAID FIRST SIGNAL, AND IN CIRCUIT WITH SAID THIRD PICKUP MEANS AND WITH SAID PHASE DETECTOR MEANS FOR BEING OPENED BY SAID THIRD SIGNAL FOR PASSING SAID PULSES FROM SAID FIRST PICK-UP MEANS, AND FOR BEING CLOSED BY SAID IMPULSE FROM SAID PHASE DETECTOR MEANS, WHEREBY THE NUMBER OF PULSES FROM SAID FIRST PICK-UP MEANS APPEARING WITHIN A TIME UNIT AT THE OUTPUT OF SAID GATE MEANS IS INDICATIVE OF THE DEGREE OF ANGULAR DISPLACEMENT OF SAID SECOND ROTATABLE MEMBER.