| 摘要 |
PROBLEM TO BE SOLVED: To lower the leaked magnetic field even in a leaked magnetic filed at a low frequency area, in which change of the interlinkage magnetic flux is small, by providing a first (heating) coil, which is spirally wound, and a second (leaked magnetic filed canceling) coil connected in series to the first coil and wound in the opposite direction to the first coil. SOLUTION: A first coil 17 and a second coil 18, which form a heating coil 13, are concentrically connected in series to each other so that the current flows in the opposite direction. A magnetic field to be generated in the first coil 17 and the second coil 18 is offset each other by the current flowing in the first coil 17 and the second coil 18 so as to lower the magnetic field to be leaked out of a device. A static magnetic field by the direct current, which can not be lowered by a shield ring, and an alternating magnetic field due to the low frequency alternating current, of which effect is low, can be lowered by flowing the same current in the opposite direction. With this structure, leak of the magnetic field out of a device in a low frequency magnetic field is thereby hindered, and generation of noise is prevented in relation to image and sound electric devices, and influence of the magnetic field to human body can be prevented. |
