| 摘要 |
PURPOSE:To control sound change in an excellent way at fade-in and fade-out and also to improve the operability by controlling a pulse width of a pulse forming a PAM signal fed to a low pass filter to attain automatically the fade-in and fade-out. CONSTITUTION:After a digital signal in response to a data expressed by a prescribed bit of code and obtained while being sampled at an interval of a time Ts of an audio signal is read from a recording medium, the data is fed to a D/A converter 2 in an information reproducing device 1. A quantized signal (a) outputted from the D/A converter 2 is a signal coincident with the time of generation of a clock pulse (c) in level change time as shown in Fig. A and its waveform is shown in Fig. B. When a fade-in swhich SW1 is depressed, a pulse width of a positive pulse outputted from a pulse width control circuit 8 is wider gradually from [0] and becomes constant. Then the pulse width of each pulse forming the PAM signal as an output of a changeover switch circuit 3 is wider gradually from [0] and the power of the PAM signal is increased gradually.
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