| 摘要 |
<P>PROBLEM TO BE SOLVED: To widen an area in which a magnetic field shield factor of a magnetic shield can be regarded uniform in an axial direction. <P>SOLUTION: A magnetic shield 9 comprises a tubular first shield 1 including openings in both ends, and a tubular second shield 2 covering an outer circumference of an area excluding a portion where a magnetic field shield factor is highest, in an axial direction of the first shield 1. Lengths, thickness and arrangements of the first shield 1 and the second shield 2 are determined such that a gradient of the magnetic field shield factor using the first shield 1 and the second shield 2 from the portion in which the magnetic field shield factor is highest to the area in which the second shield 2 is disposed becomes smoother than a gradient of the magnetic field shield factor using only the first shield 1. <P>COPYRIGHT: (C)2013,JPO&INPIT |
