| 摘要 |
PROBLEM TO BE SOLVED: To easily and well suppress the partial magnetizing force variation of a core by providing a partition which prevents the winding of a coil on the shaft section of a primary coil bobbin around which the coil is wound. SOLUTION: A partition 61 having a prescribed width (w) is provided at the central part of the shaft section of a coil bobbin 6 around which a primary coil 5 is wound so as to prevent the winding of the coil 5 around the part. Consequently, the number of tuns of the coil 5 at the central part, where the reverse bias magnetizing force becomes the weakest due to the long distances from the permanent magnets 10 provided at both ends of a bar-like core 9 inserted into the hollow shaft of the bobbin 6, can be reduced to about zero at the time of installing the magnets 10 to both ends of the core 9. Alternatively, a plurality of partitions are provided at appropriate spots of the shaft section of the bobbin 6 wound with the coil 5 in such a way that the widths of the partitions are adjusted in accordance with the degree of variation of the magnetic force of the core at their spots due the permanent magnets 10. |
