Musical-tone signal forming apparatus for an electronic musical instrument

Abstract

Abstract A musical-tone signal forming apparatus for an electronic musical instrument is characterized by the use of a musical-tone waveform setting circuit by which repeatedly at least one cycle of a musical-tone waveform is sampled at n points so the amplitude thereof at each sampling point can be compared with the amplitude thereof at the preceding sampling point and an increase signal, an equal signal, or a decrease signal is generated as a digital signal. Also employed is an envelope setting circuit in which an envelope of a musical tone is sampled at m points and the analog amount thereof at each sampling point is generated as a corresponding digital signal. An integrating circuit is used in which the digital signals of the envelope setting circuit are accumulatively added or subtracted according to the digital signals of the musical-tone waveform setting circuit. The output signal of the integrating circuit is taken out through a D-A converter as a musical-tone signal. The integrating circuit comprises full adders connected in tandem and latch circuits provided on the output side thereof. AND circuits and exclusive OR circuits are interposed between the musical-tone waveform setting circuit and the envelope setting circuit and the full adders. The musical-tone waveform setting circuit is provided at its input side with a clock pulse generator, which generates a clock pulse signal corresponding to the frequency of a musical-scale tone by use of an order pulse generator and a counter. Each of the latch circuits is operated at the descending portion of each pulse generated by the clock pulse generator.

Inventors

• 👤 Toshio Kugisawa

Bibliographic Details