| 摘要 |
<p>PURPOSE:To improve the output sound pressure level in virtue of the resonance in a space by a piezoelectric element itself, and obtain the directivity of a sound field in a plurality of directions. CONSTITUTION:A piezoelectric element 1 has a structure wherein an inner electrode 3 and an outer electrode 4 are formed on the inner surface and the outer surface of a piezoelectric film body 2 which is composed of polymeric piezoelectric material and formed as a close-end cylinder (approximate bottle type). Since the piezoelectric element 1 has a semi-closed structure of the element itself, the output sound pressure level can be improved in virtue of the resonance in a space without arranging the element in a box of closed or semi- closed structure. The piezoelectric element 1 of the close-end cylinder type vibrates in whole, so that the directivity of a sound field can be constituted in a plurality of directions.</p> |
