To improve static pressure span characteristics by reducing an area of a conductive film coated to a surface opposite to a diaphragm in a fixed electrode facing close to the diaphragm.
A fixed electrode comprises an insulating plate 1 having a pressure introduction central hole 1a, a conductive plate 12, a supporting body 21 and a gold conductive film 2. The conductive film 2 is integrally constituted of a part 2a covering the whole inner circumference of the central hole 1a, a part 2b covering a ring-shaped area of a square surrounding the central hole 1a and a part 2c covering a band-shaped area extending from the ring-shaped area to reach the outer periphery. The conductive film 2 is connected to the conductive plate 12 at a terminal part of the part 2a and to capacitance-taking terminals 31, 32 at a terminal part of the band-shaped area 2c. In the constitution, a total area of the ring-shaped part 2b and band-shaped part 2c of the conductive film 2 coated to a surface of the fixed electrode at the opposite side to a diaphragm 10 is reduced, so that static pressure span characteristics are improved.
NAKAMURA KIMIHIRO
YUHARA TADANORI
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