Electronic musical instruments which form musical tones by repeatedly generating musical tone waveform elements

DETAILED DESCRIPTION Accordingly, it is the principal object of this invention to provide an improved electronic musical instrument wherein musical tones are formed by repeatedly generating musical tone waveform elements by a multiplication product of two different waveforms whose periods are respectively variable so that the color of the generated musical tone can readily by varied with a relativey simple construction.
Another object of this invention is to provide an electronic musical instrument capable of varying with time the tone color of the generated musical tone in addition to the performance described above.
According to this invention, there is provided an electronic musical instrument comprising a plurality of key switches which determine tone pitches of musical tones generated by the musical instrument; a periodic trigger pulse generating circuit which generates a trigger pulse having a period corresponding to a designated one of the key switches; a constant parameter generator which generates a predetermined constant parameter; first and second waveform generators responsive to the periodic trigger pulse and to the output of the constant parameter generator for producing outputs having different waveforms; a multiplying circuit to multiply with each other the outputs of the first and second waveform generators for producing a musical tone waveform element; the first waveform generator generating an oscillatory waveform; the second waveform generator generating another waveform which builds up from a predetermined reference level to a higher level and then decreases toward the reference level; the musical tone waveform element having an envelope which increases from zero to a predetermined value and then decreases to zero; and means for repeatedly generating the musical tone waveform element at a period corresponding to the period of the trigger pulse so as to form a musical tone wave thereby repeatedly generating the musical tone waveform element to form the musical tone.