| 摘要 |
PURPOSE: To form a magnetic seal part with high yield rate of materials by constituting a doughnut magnetic shield part by overlapping end parts of a plurality of conductive metal plates and arranging the shield part in the circumference of a heater coil. CONSTITUTION: When high frequency current is supplied to a heater coil 15 from a frequency converting apparatus 18, a magnetic field is generated from the coil 15, the magnetic filed crosses a pan made of iron put on a top plate 16, and the pan is heated by the eddy current generated in the pan. Meanwhile, the magnetic field generated in the coil 15 crosses also a closed curved face formed in a magnetic shield part 19 and induction current is generated in the magnetic shield part 19. For that, in the inner side of the magnetic shield part 19, the magnetic field is intensified due to the induction current and on the other hand, in the outer side of the magnetic shield part 19, the magnetic field is weakened, so that the magnetic field in the outside can be suppressed. Moreover, since the magnetic shield part 19 is installed like a strip in horizontal direction, the part 19 is easy to be inserted in a narrow gap between a holding part 13 and the top plate 16 and is hard to be affected by a pan. |
