| 摘要 |
PURPOSE:To prevent the generation of click noise by performing the multiplication of plural key touch signals at time sharing multiplexing and signals corresponding to key touch pitches when the level absolute values of the signals are below specified value thereby forming musical tone signals. CONSTITUTION:Key switch circuits corresponding to plural key touches are scanned by specified timing signals and the time-shared multiplx key touch signals are applied to a keying control circuit 60 via adder, etc. On the other hand, a time shared waveform generating circuit is scanned in synchronization with key scanning and the waveform signals corresponding to the key touch piches are applied from sign table 21 to the level detecting signal generating circuit 70 of the circuit 60 and when the absolute value of the levels of the input waveforms is less than a specified value, the circuit 70 generates a detection signal and controls its gate. This causes the time shared multiplex key touch signals to be stored in a memory circuit 80 formed by the shift registers of the circuit 60 only when the absolute value of the pitch waveform levels is below the specified value, then the pitch waveforms and the storage contents of the circuit 80 are multiplied in a multiplier 5, whereby the good musical tone signals free from click noise accompanied by keying are formed. |
