| 摘要 |
PURPOSE:To enable to achieve an output sound pressure frequency characteristic over a wide range, by piezoelectric driving of one diaphragm plate at a high frequency region and dynamic driving at the low frequency region. CONSTITUTION:A metal diaphragm plate 15 is bonded with a piezoelectric plate 16 fixed with an electrode 17. Further, a voice coil 18 is bonded to the diaphragm plate 15 and the coil 18 is in the magnetic circuit formed with the magnet 19, yoke 20, and pole 21, allowing to exert the driving force according to the signal current to the diaphragm plate 15. With this constitution, at a low frequency region, the diaphragm plate 15 is unifiedly driven with the driving force by means of the coil 18 dynamically, and at high frequencies, a voltage is fed to the plate to drive the diaphragm plate 15 with the piezoelectric plate 16 extending and shrinking with the plate surface direction for piezoelectric drive. Thus, the sound pressure characteristics is made flat over a wide frequency band. |
