| 摘要 |
PURPOSE:To eliminate influence of weak external magnetic field such as geomagnetism, by a method wherein a magnetic material is entered in a magnetic shield case having Curie temperature higher than that of the magnetic material, and then heated to a temperature higher than Curie temperature of the magnetic material and lower than that of the magnetic shield case. CONSTITUTION:A magnetic material 2 is entered in a magnetic shield case 3 having Curie temperature higher than that of the magnetic material 2, and then the magnetic material 2 is heated to a temperature higher than Curie temperature of the magnetic material 2 and lower than that of the magnetic shield case 3. For example, the magnetic shield case 3 is made of Fe-Co alloy of Curie temperature 990 deg.C in cylindrical form. The magnetic material 2 to be demagnetized is made of permalloy and treated in an electric furnace 9 for 20-30min at a temperature of 500 deg.C higher than the Curie temperature being about 420 deg.C. |
