| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide the sound volume adjustment circuit in which a pulse width modulation(PWM) signal, whose duty ratio varies with the operation of the user is in use. SOLUTION: A PWM signal generating means 11 generates a PWM signal whose duty ratio varied with the operation of an up key/down key by the user, a rectifier means 12 converts the generated PWM signal into a DC level, a sound signal level adjustment integrated circuit element 13 compares and amplifies a level of a sound signal received from a sound signal input means 10 and the DC level outputted from the rectifier means 12 to adjust a level of the sound signal, the sound signal whose level is adjusted by the input means 10 sound signal level adjustment integrated circuit element 13 is processed by a sound signal processing means 14 and outputted via a sound output means. Thus, noise or the like is not produced, even after the use for a long time and in the case of muting the sound signal, pop noise or the like is not generated by adjusting a width of a pulse outputted from the PWM signal generating means 11.</p> |
