PHASE CORRECTION TYPE ACTIVE MAGNETIC SHIELD DEVICE

PROBLEM TO BE SOLVED: To provide a phase correction type active magnetic shield device securely cancel a disturbing magnetic field of an AC magnetic field and a time-varying magnetic field by removing a residual magnetic field signal corresponding to a magnetic field remaining without being canceled because the disturbing magnetic field and a canceling magnetic field are not in phase with each other. SOLUTION: A phase correction signal similar to the residual magnetic field signal is generated by a phase correction signal generating means 10 so as to remove the unnecessary residual magnetic field signal included in an output signal of a magnetic sensor S, and the phase correction signal and residual magnetic field signal are made to cancel each other through an adding/subtracting means 12, thereby removing the residual magnetic field signal. The phase correction signal generating means 10 includes a phase synchronizing means 17 for synchronization with the output signal phase of the magnetic sensor S and an amplitude adjusting means 18 with a polarity switching function for changing the phase of the phase correction signal in accordance with the output signal phase of the magnetic sensor S. COPYRIGHT: (C)2010,JPO&INPIT