| 摘要 |
<p>A housing (31) has a surface. A coil (34) is disposed at the back of a part of the area on the surface. The expected range of the part of the area is a part or whole of an area (AR). The part of the area is processed so that a metal seal tends not to bond thereto. Any one of the following processing methods may be employed: A. The part of the area is formed as a projection (31a). B. The part of the area is rough and not smooth. C. The part of the area is raised with respect to the surrounding area. D. The part of the area is depressed with respect to the surrounding area. These processing methods facilitate the peeling off of a metal seal and thus prevent dielectric heating.</p> |
