| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a human body from getting an electric shock even when it touches an electrode of an electrostatic type electroacoustic transducer. <P>SOLUTION: Signals of sine waves outputted from an oscillator 140 are supplied to conductive films 50U and 50L. Acoustic signals are amplified in an amplifier part 130, boosted in a transformer 110, and outputted to electrodes 20U and 20L of an electrostatic type speaker. When a human body approaches the conductive films 50U and 50L, a voltage applied to a capacitor C1 increases. The voltage applied to the capacitor C1 is amplified in an amplifier circuit 210 and measured in a control part 230. When a voltage value of an output terminal of an operational amplifier 131 exceeds a predetermined threshold, the control part 230 executes control so as to maintain the state that switches SW1-SW3 are open. Thus, output of the acoustic signals to an electrostatic type speaker 1 is stopped. <P>COPYRIGHT: (C)2013,JPO&INPIT |
