| 摘要 |
PURPOSE:To reduce the added weight to a speaker and to improve the acoustic characteristic such as oscillation tracking performance, by selecting diameter and thickness of the piezoelectric element to a value in specific range, and making light the weight of a piezoelectric element. CONSTITUTION:A support ring 9 is provided on a disc cap 8 of a voice coil bobbin 7 provided at the center of a diaphragm plate 6, and the circumference of the piezoelectric element 3 of disc shape is bonded on the support ring 9. The diameter of the element 3 is >=10mm. and <=25mm., and the thickness is >= 100mum and <=200mum. The amount of oscillation of a diaphragm plate 6 of a speaker is detected with the piezoelectric element 3. |
