| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a driving circuit capable of preventing a person from receiving electrical shock even when the person touches an electrostatic speaker. <P>SOLUTION: A driving circuit comprises: an oscillator 140 for outputting a sine wave addition signal; an adder 150 for adding the addition signal to a sound signal; an amplifying unit 130 for amplifying the sound signal; a transformer 110 for raising a voltage of the sound signal to output the raised voltage to electrodes 20U and 20L of an electrostatic speaker 1; a detection circuit 210 for outputting a signal corresponding to a current value of a current flowing in a resistor R4, the current being increased when a person touches the electrodes 20U and 20L; a filter 220 for filtering a frequency component of the addition signal of the signals outputted from the detection circuit 210; and a control unit 230 for controlling switches SW1 to SW3 so that they are maintained in those open state, when a voltage of the signal passing through the filter 220 exceeds a predetermined threshold value. Accordingly, the sound signal outputted to the electrostatic speaker 1 is stopped. <P>COPYRIGHT: (C)2012,JPO&INPIT |
