| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a device for suppressing and reducing the influence of output distortion characteristics caused by a variation in power supply voltage by a battery. <P>SOLUTION: The device has a battery voltage detection circuit 103 for detecting the voltage of the battery 101 and driving circuits 107 and 108 each including an operational amplifier for inputting the voltage of the battery 101 as a driving power supply voltage, differentially inputting an input signal from a sound source circuit 106 and a reference voltage from a reference voltage generation circuit 105, and driving a speaker 109 on the basis of the differential voltage, and is provided with a control circuit 104 for adjusting the reference voltage of the driving circuit into voltage suitable for the battery voltage by controlling the reference voltage generation circuit 105 by detecting the battery voltage with the battery voltage detection circuit 105 in response to an instruction which is outputted when an event to drive the speaker 109 with the driving circuit occurs. <P>COPYRIGHT: (C)2003,JPO |
