JPS54153018A - Electronic musical instrument - Google Patents

Abstract

PURPOSE: To produce multiple sounds simultaneously from each keyboard with a simple constitution by making operations corresponding to key touch pitch waveform codes and the weighted key touch codes which a coupler control circuit subsequently outputs with delays for each keyboard thereby forming the musical tone signals.

CONSTITUTION: Switch circuits 43 thru 45 of an upper keyboard 15, lower keyboard 25 and pedal keyboard 30 are scanned by a timing signal generating circuit 1, then the time division multiple codes corresponding to the key touch states of the respective keyboards are applied to the first upper keyboard musical tone production control circuit 17, etc. forming a coupler control circuit by being connected to the draw bar 18, etc. of an upper keyboard musical tone production circuit 3, etc. The circuit 17 outputs the logarithmic key touch codes corresponding to the number of key touches given with weights in the specified order at the specified delay intervals. On the other hand, the logarithmic pitch waveform codes of time division corresponding to the key touching are generated from the sine table 14 of a time division waveform generating circuit 2. In the first musical tone forming circuit 23, etc., the musical tone signals are formed by multiplication of the pitch waveform codes and the key touch codes from the circuit 17.

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