Tuning fork resonator with driving and feedback coils decoupling

Claim 1

ELECTRO-MECHANICAL RESONATOR APPARATUS COMPRISING A TUNING FORK, INPUT TERMINALS ADAPTED TO BE CONNECTED TO A DRIVING SIGNAL SOURCE, A FIRST PAIR OF COILS CONNECTED IN SERIES BETWEEN SAID INPUT TERMINALS AND LOCATED EXTERNALLY ADJACENT RESPECTIVE TINES OF SAID TUNING FORK, MEANS FOR SUPPLYING A CONSTANT BIAS MAGNETIC FLUX TO EACH OF SAID FIRST PAIR OF COILS, A SECOND PAIR OF COILS LOCATED EXTERNALLY ADJACENT RESPECTIVE TINES OF SAID TUNING FORK, MEANS FOR SUPPLYING A MAGNETIC FLUX TO EACH OF SAID SECOND PAIR OF COILS, SAID FLUX HAVING A DIRECTION IN A GAP BETWEEN EACH SAID COIL AND A TINE OF SAID FORK SUBSTANTIALLY PARALLEL TO THE PLANE OF VIBRATION OF SAID FORK, THE MAGNETIC FLUX SUPPLIED TO ONE PAIR OF COILS BEING IN THE SAME DIRECTION IN BOTH COILS AND THE MAGNETIC FLUX SUPPLIED TO THE OTHER PAIR OF COILS BEING IN OPPOSITE DIRECTIONS IN THE RESPECTIVE COILS OF THE PAIR, OUTPUT TERMINALS AND MEANS FOR CONNECTING SAID SECOND PAIR OF COILS IN SERIES BETWEEN SAID OUTPUT TERMINALS SO THAT THE SIGNAL SUPPLIED TO SAID OUTPUT TERMINALS BY THE FIRST COIL OF SAID SECOND PAIR OF COILS DUE TO INDUCTIVE COUPLING FROM SAID FIRST PAIR OF COILS IS OPPOSITE IN SENSE TO THAT SUPPLIED BY THE SECOND COIL OF SAID SECOND PAIR OF COILS, WHEREBY INDUCTIVE COUPLING BETWEEN SAID INPUT TERMINALS AND SAID OUTPUT TERMINALS IS SUBSTANTIALLY ELIMINATED.