| 摘要 |
PURPOSE:To erase the unpleasant shock sound by reading the key input information into the interface and at the same time actuating the muting circuit through the OR circuit and by the control voltage. CONSTITUTION:The timing pulse is supplied to keyboard switch 21 from keyboard input interface 14. At the same time, the key information is read into interface 14. While control wire 22 is led out from switch elements a-i to be connected to one end of plural number of switch 23 each along with the other end connected to power source 24 of the HI level. Furthermore, if the HI-level signal emerges at enve one of wires 22, OR circuit 25 delivers the HI-level signal to the latch circuit 26 to be held for an appropriate time. Then the output is applied to muting circuit 27 to eliminate the unpleasant shock sound occurring at the time of key operation. |
