| 摘要 |
PURPOSE:To prevent the generation of an impact crashing sound from a speaker at the ON/OFF time of a band noise generator, by mounting a timing signal generating circuit comprising an oscillator and a delay circuit consisting of a wave-form shaping circuit and a D.FF circuit. CONSTITUTION:The band noise (BN) signal inputted to a speaker from a band noise (BN) generator through a noise amplifier is converted to a rectangular wave signal by the wave-form shaping circuit 110 of a control part 13 to be inputted to the T-terminal of D.FF111. The oscillation pulse outputted from an oscillator 101 is inputted to the D-terminal of D.FF111 and outputted from a Q-terminal while delayed by one clock of a rectangular wave signal amplitude and applied to the noise amplifier as an ON/OFF control signal to control the opening/closing of the gate thereof. By this method, the crashing sound emitted from the speaker at the ON/OFF time of the BN signal can be prevented. BN is easy to generate as a frequency band becomes lower but, because this method controls the opening/closing of the gate of the noise amplifier at the time of the zero cross of BN signal amplitude, the action thereof becomes more effective the more frequency becomes low and an impact crashing sound becomes difficult to generate.
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