| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a ceramics layer from cracking in the case of forming a center hole to a piezoelectric diaphragm. SOLUTION: A through-hole 32 is formed at the center of a metallic thin plate 30 formed to be a prescribed shape, ceramics layers 34, 36 are adhered to both sides of the metallic thin plate 30, a punch P' whose outer diameter is equal to or smaller than an inner diameter of the through-hole 32 is positioned with respect to the through-hole 32 on the surface of the one ceramics layers 34 adhered to the metal-made thin plate 30, the punch P' is penetrated from the surface of the ceramic layer 34 to the other ceramic layer 36 via the through-hole 32 to form a center hole 38, and a center support member 18 is penetrated and fixed at the center hole 38.</p> |
