| 主权项 |
1. A piezoelectric speaker comprising:
a diaphragm including a substrate and a plurality of piezoelectric elements arranged on said substrate; and a frame supporting said substrate at an outer peripheral portion of said substrate, wherein each of said plurality of piezoelectric elements includes at least one piezoelectric body and at least one electrode, the at least one piezoelectric body and the at least one electrode being stacked, wherein said plurality of piezoelectric elements includes a first piezoelectric element having a first number of layers, and second and third piezoelectric elements, each having a second number of layers, the first number of layers being larger than the second number of layers, wherein said first piezoelectric element has a first contribution ratio to amplitude, and said second and third piezoelectric elements each have a second contribution ratio to amplitude, the first contribution ratio to amplitude being larger than the second contribution ratio to amplitude such that a distortion of said first piezoelectric element is larger than a distortion of each of said second and third piezoelectric elements, wherein said first piezoelectric element is arranged on said substrate in a portion having a first stress, said second piezoelectric element is arranged on said substrate in a portion having a second stress, and said third piezoelectric element is arranged on said substrate in a portion having a third stress equal to the second stress, the first stress being smaller than the each of the second and third stresses, wherein the first, second, and third stresses are caused by a bending vibration of said substrate, and wherein said second piezoelectric element and said third piezoelectric element are symmetrically arranged with respect to a center of said substrate. |
