| 摘要 |
PROBLEM TO BE SOLVED: To increase the heating degree of a portion other than the middle part of a doughnut-shaped heating coil by making part of a heating coil a part consisting of a plurality of wound sections and setting the degree of induction heating so as to be partially high. SOLUTION: A ferrite 2 is layered on the top surface of an aluminum substrate 1, and around the top surface of the ferrite 2, a conductor 30 is wound spirally in a doughnut-shaped range to form a heating coil 3. The heating coil 3 consists of a lower coil part 3a where one conductor 30 is wound around the top surface of the ferrite 2 closely at one stage in a spiral shape and an upper inner coil 3b on the central side provided at the top surface of the lower coil part 3a and an upper outer coil 3c on the peripheral edge side. A part where the lower coil part 3a and the upper coil 3b are piled up and a part where the lower coil part 3a and the upper outer soil 3c are piled up forms a part consisting of a plurality of wound sections. The inductive current on the central side of the heating coil 3 whose heating coil is relatively low increases, thus it is possible to prevent uneven heating which causes insufficient heating on the central side. |
