| 摘要 |
Vibrating electrode plate (24) sensitive to sound pressure is disposed opposite to counter electrode plate (25) to thereby construct a capacitance type acoustic sensor. The counter electrode plate (25) is provided with acoustic perforation (31) for passage of vibration, and on its surface opposite to the vibrating electrode plate (24) is provided with multiple projections (36). The spacing between adjacent projections (36) is reduced at an area of the vibrating electrode plate (24) having high flexibility to thereby cause easy local sticking to the counter electrode plate (25). On the other hand, the spacing between adjacent projections (36) is increased at an area of the vibrating electrode plate (24) having low flexibility to thereby render any local sticking to the counter electrode plate (25) less probable. By virtue of this arrangement of projections, there can be prevented fixation of the vibrating electrode plate to the counter electrode plate leading to blocking of the vibration of the vibrating electrode plate. |
