| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic shield room that eliminates entrance of noise into a magnetoencephalograph by preventing stray current from flowing into the magnetic shield room in a frequency band that the magnetoencephalograph requires by supplying a compensating current by a differential amplifier since the stray current does not flow through an additional ground line as the potential of a ground point is applied to a noninverting terminal of the differential amplifier through the additional ground line. SOLUTION: The magnetic shield room is a magnetic shield room connected to the ground line by connecting the ground line to a ground electrode connected to the ground, and has the additional ground line extending from the ground point of the ground line connected to the ground electrode to nearby the magnetic shield room, the differential amplifier, and a protective resistance connected between the output terminal of the differential amplifier and the ground line nearby the magnetic shield room, wherein the additional ground line is connected to the noninverting input terminal of the differential amplifier and the ground line nearby the magnetic shield room is connected to the inverting input terminal of the differential amplifier to form a compensating current which supplies the compensating current to the ground line of the magnetic shield room. COPYRIGHT: (C)2009,JPO&INPIT
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