| 摘要 |
PURPOSE:To obtain a speaker which features a high efficiency and is capable of reproduction for a sufficiently low sound by combining quite different principles of the dynamic and piezoelectric types. CONSTITUTION:Coil conductor layer 10 functioning as a plane coil as well as an electrode layer is provided on one surface of high molecular piezoelectric film 8, along with full-surface electrode layer 9 provided on the other surface each. Thus vibrating film 7 is formed to be stretched out via frame 11. Then bar magnet 12 and magnetic plate are distributed in opposition to each other and holding film 7 between, thus forming magnetic circuit. The aural current is flown to coil conductor 10 from the low-impedance signal source to secure the operation as a full-surface driving type dynamic speaker. At the same time, the full-wave rectified aural signal is applied between conductor 10 and layer 9 so that film 7 may extend according to the absolute value of the aural signal. Furthermore, resistance 25 satisfying a fixed conditions is connected in parallel to the area between layer 9 and the coil conductor layer. In such constitution, a high-efficiency reproduction is possible for the low sound. |
