| 摘要 |
PURPOSE:To make this system compact, and to attain an excellent converting efficiency by using plural sounders which has a different frequency band, and outputs the signal of the necessary frequency band as a whole, and generating an output sound from each sounder through a BPF. CONSTITUTION:As for a sounder 30, a unimorph type piezo-electric diaphragm 1 is inserted into a plastic case 2, and an input signal is applied from an input terminal 5 of this diaphragm 1, so that the sound can be outputted by using the basic resonance of the diaphragm 1, and the resonance due to a previous air chamber 3 and a sound hole 4. This has a high sensitivity while it is compact. As for this electric equivalent circuit, the sounder 30 is a resonance circuit which is constituted of a coil L1, and capacitors C1-C3, indicated by a b figure. A resonator 31 connected with this, is constituted of a coil L2 and a capacitor C4, and moreover a resonator 32 is constituted of a coil L3, so that they can be turned into low pass or band pass filters. Thus, the entire system can be attained at a low cost, and it can be used as a digital system. |
