Fast and slow dual photo-cell bridge plural servo-motor control for duplicating machines

Claim 1

SYSTEM FOR CONTROLLING THE RELATIVE MOVEMENT BETWEEN A WORK PIECE AND A CUTTING ELEMENT IN A CONTOURING MACHINE IN WHICH BOTH THE WORK PIECE AND A CONTROL TEMPLATE ARE CARRIED BY A WORK TABLE MOUNTED FOR RECTILINEAR MOVEMENT IN TWO DIRECTIONS AT RIGHT ANGLES TO EACH OTHER, AND A SENSING DEVICE COOPERATES WITH THE EDGE OF SAID TEMPLATE TO PRODUCE DISTINGUISHABLE RESPONSES UPON A DEPARTURE OF THE TEMPLATE TOWARDS OR AWAY FROM SAID SENSING DEVICE, SAID SYSTEM COMPRISING A PAIR OF REVERSIBLE FEED MOTORS FOR DRIVING SAID WORK TABLE IN DIRECTIONS AT RIGHT ANGLES TO EACH OTHER, CIRCUIT MEANS FOR ENERGIZING SAID MOTORS TO EFFECT A CONSTANT RATE OF RELATIVE MOVEMENT BETWEEN SAID CUTTING ELEMENT AND SAID TABLE, SAID CIRCUIT MEANS INCLUDES MEANS FOR VARYING THE SPEED OF ONE MOTOR ACCORDING TO THE SINE FUNCTION OF THE ANGLE BETWEEN THE DESIRED DIRECTION OF CUTTING AND THE DIRECTION OF TABLE DRIVE BY ONE OF SAID MOTORS, AND FOR VARYING THE SPEED OF THE OTHER MOTOR ACCORDING TO THE COSINE FUNCTION OF THE SAME ANGLE, SAID CIRCUIT MEANS ALSO INCLUDING AN ERROR BRIDGE CONTROLLED BY SAID SENSING DEVICE, AND BEING OPERABLE IN RESPONSE TO DEPARTURE OF THE TEMPLATE FROM THE SENSING DEVICE IN ONE DIRECTION TO EFFECT OPERATION OF SAID MOTORS IN ONE DIRECTION, AND RESPONSIVE TO DEPARTURE OF THE TEMPLATE FROM THE SENSING DEVICE IN THE OPPOSITE DIRECTION, TO REVERSE THE DIRECTION OF OPERATION OF SAID MOTORS, WHEREBY SAID SYSTEM IN EFFECTIVE FOR CONTROLLING SAID WORK TABLE SO THAT SAID CUTTING ELEMENT MAY TRACE A COMPLETELY CLOSED PATH ON SAID WORK PIECE, SPEED-CONTROL MEANS CONTROLLED BY SAID SENSING DEVICE UPON DEPARTURE OF SAID SENSING DEVICE FROM THE EDGE OF SAID TEMPLATE TO VARY THE SPEEDS OF SAID MOTORS TO EFFECT A CHANGE IN THE DIRECTION OF MOVEMENT OF SAID TABLE, SAID SPEED-CONTROL MEANS COMPRISING TWO-INTERLOCKED POTENTIOMETERS CONTROLLED BY SAID SENSING DEVICE AND HAVING SINE AND COSINE OUTPUT CHARACTERISTICS RESPECTIVELY, AND A PAIR OF SERVO-MOTORS CONTROLLED BY SAID POTENTIOMETERS AND OPERATING SAID FEED MOTORS AT SPEEDS IN ACCORDANCE WITH THE VOLTAGE OUTPUTS OF SAID POTENTIOMETERS, AND SAID SPEED-CONTROL MEANS INCLUDING A NORMALLY BALANCED ERROR BRIDGE CONTROLLED BY SAID SENSING DEVICE AND BEING UNBALANCED UPON DEPARTURE OF SAID SENSING DEVICE FROM A NORMAL TRACING POSITION WITH RESPECT TO SAID TEMPLATE, A BALANCING POTENTIOMETER CONNECTED IN SAID ERROR BRIDGE, AND MEANS FOR OPERATING SAID BALANCING POTENTIOMETER BY OPERATION OF SAID INTERLOCKED POTENTIOMETERS.