| 摘要 |
PURPOSE:To obtain a high sound pressure level over broad bands, by forming a diaphragm as a shape where it is swelled once from the center to the outer circumference to be detached from a piezoelectric element and then swelled down to the piezoelectric element and fixing the outer circumference of the downward part to a frame. CONSTITUTION:The diaphragm 4 is formed as a shape where it is swelled up once for the center part 4a to be detached from the piezoelectric element 2 and then down to the element 2, and a flat outer circumference 4b provided at the outside is fixed to the frame 1. When the element 2 is deformed, and the diaphragm 4 is displaced from the position in broken lines to that in solid lines. Thus, the center part 4a of the diaphragm 4 is driven up and down, but the outer circumference 4b is fixed at a point lower than a point swelled up once, then the damping by the fixed outer circumference is absorbed at the swelled-up part for the most part. Then, the movement of the element 2 is delivered accurately to the diaphragm 4, which is driven over broad bands at a high efficiency. |
