| 摘要 |
PURPOSE:To always hold a diaphragm by means of a proper compression force, by a method wherein a projection with a given height, forced into the one of two cases serving to hold the diaphragm, to determine the compression volume of the diaphragm, is provided at least on the other case. CONSTITUTION:A holding part for the outer end of a diaphragm 7 is formed such that flange parts 8 and 9 of two cases 1 and 2, respectively, are superposed with each other and the diaphragm 7 is nipped therebetween. Plural projections with a given height (h) formed in a small column are annularly provided on a flange part 8 of the case 1. The projections 10 are formed so as to make contact with a flange part 9 of the case 2, the height (h) is set to a value slightly lower than the thickness of the diaphragm 7, and forms a size by which the final compression volume of the diaphragm 7 is determined.
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