US 4,282,790 A · Electronic musical instrument

Abstract

More than one sub-intervals or time-windows are provided in a one-cycle period of a musical tone selected at a keyboard of an electronic musical instrument. Each time-window passes a sine wave having a frequency predetermined for the time-window. The envelope of the spectrum of a time-window is determined by the shape and the width of the time-window, and the envelope of the spectrum of a sine wave passed from the time-window will become the convolution of the spectrum of the time-window and the frequency of the sine wave. The total area of the frequency spectrum included as frequency components of a musical tone can be covered by several time-windows, each having a different length and passing a sine wave of a different frequency. An amplitude control means controls the amplitude of each sine wave independently. The controlled amplitude level determines the spectrum intensity of the frequency region influenced by the corresponding sine wave. When the levels of all the sine waves are properly controlled, the resultant harmonic contents will be a desired one which produces a desired tone quality.

Claims16

Dependent claims

An electronic musical instrument comprising:

means for repeatedly generating a waveshape having a frequency which changes as a function of time from the start point of said waveshape, said start point of said waveshape being synchronized with a predetermined phase point of the fundamental period of a musical tone to be generated and said waveshape being terminated within a period of said fundamental period of said musical tone;
an amplitude control means for controlling the amplitude of said waveshape in correspondence with said frequency changing as a function of time within said fundamental period;
and
a sound system means for producing a musical tone from the output of said amplitude control means.

1 more element

An electronic musical instrument for producing a musical tone having a fundamental with a period To, comprising:

time-window generation means for producing a consecutive set of time-window signals each establishing a respective time interval which is a different fractional portion of said fundamental period To,
first sine wave generation means, cooperating with said time-window generation means, for generating during each respective established time interval a sine wave signal having a frequency that is a different harmonic of said fundamental,
coefficient generation means, cooperating with said time-window generation means and said sine wave generation means, for respectively independently scaling said generated sine wave signals by a separate coefficient for each time interval, and
sound conversion means for converting said scaled sine wave signals to a musical tone.

1 more element

A digital electronic musical instrument comprising:

accumulator means for repetitively accumulating with a fixed modulus at a set clock rate a selected frequency number related to the fundamental frequency of a musical tone,
a wave shape memory storing sampled amplitudes of a sine wave,
decoder means, responsive to the contents of said accumulator, for producing a set of time interval control signals respectively establishing time intervals that are different fractional portions of the period of said fundamental frequency,
bit shift circuitry, cooperating with said decoder means, for causing the contents of said waveshape memory to be accessed using as sample point specifying addresses different subsets of said accumulator contents in accordance with the value of said time interval control signals, and
digital-to-analog conversion means for converting the accessed sampled amplitudes from said waveshape memory to musical tones.

2 more elements

Dependencies are inferred from the claim text.

Electronic musical instrument

Life of this patent

Electronic musical instrument

Life of this patent

Abstract

Claims16