| 摘要 |
PURPOSE: To obtain a sound volume control device prepared for an electronic volume or the like and having excellent noise resistance and follow-up property and its controlling method. CONSTITUTION: The sound volume control device is provided with a variable resistor 1 for dividing voltage for adjusting sound volume, an A/D converter 2 for converting the output voltage of the resistor 1 into a digital value and outputting a sampling value, an arithmetic circuit 3 for outputting a reference value for setting up sound volume corresponding to the output value of the A/D converter 2, and an electronic volume 4 for setting up sound volume based upon the reference value. When changes more than a fixed value from a current reference value are generated in sampling values plural times or the mean value of sampling values obtained within a fixed time is changed more than a fixed value from the reference value, the sound volume is changed. |
