Abstract: In an electronic musical instrument wherein a frequency information related to the tone pitch of a depressed key is repeatedly accumulated and the progressing accumulated value is used to designate the addresses of a waveform memory device storing the waveform of a desired musical tone, the frequency information is varied with time instantaneously so as to vary the speed of addressing the waveform memory and thereby to vary the waveform read out from the waveform memory device, thus changing the color of the produced musical tone.

Abstract: An electronic musical instrument is provided with a plurality of wave shape memories storing different musical tone wave shapes of different memory sizes for different tone ranges. The memory for the treble tone is of a small size and that for the bass tone is of a large large size. When a key is operated in the keyboard, a memory corresponding to the tone range to which the operated key belongs is selected and read out. While successfully avoiding economically disadvantageous increase in the memory size of the wave shape memories, beautiful and clear musical tones can be obtained having different tone colors for different tonal pitches just like those generated by natural musical instruments.

Abstract: A CPU of a computer, or preferably a so-called microprocessor controls the tone waveshape generation. A tone generator unit, an instrument keyboard unit, a tone quality control unit are connected to a common data bus to which the CPU and the associated memories are also connected. Thus, the tone generator unit may be considered as a terminal unit of a computer system. Hence, the freedom in selecting the algorithm for generating a waveshape and the freedom in selecting and changing the parameters related to the waveshape generation are substantially increased. And therefore a gradually changing waveshape is very easily generated in one embodiment of this invention.

Abstract: The musical instrument is of a waveform memory device read out type and comprises a frequency information generator for generating a plurality of sets of frequency informations each set consisting of a subplurality of frequency informations and corresponding to each of the tone pitches of the depressed keys in a keyboard, a selector for selecting one, at a time and one after another, of the subplurality of frequency informations generated by the frequency information generator for each one key depressed, an accumulator for repeatedly accumulating the frequency information selected by the selector to produce an increasing accumulated value, a waveform memory device for storing the amplitude values at successive sampling points in one period of a sine wave utilized to form a desired musical waveform, a comparator for comparing the accumulated value with a preset value and controlling the selecting operation of the selector during the operation of the accumulator.

Abstract: Musical tone signals are produced in an electronic musical instrument by calculating the amplitudes at successive sample points of a complex waveshape and by delivering these calculated amplitudes one after another in time sequence. A recursive algorithm is implemented to calculate each amplitude, using one or more sets of parameters and also the calculated amplitudes for a plurality of the preceding sample points. This musical instrument can produce a variety of musical sounds which realistically simulate those of the various existing natural musical instruments including percussion instruments, simply by suitably determining the parameters.

Abstract: An electronic musical instrument comprises a waveshape memory delivering out digital value samples of one cycle of a certain waveshape, and a loop circuit including a filter and a shift register. The digital waveshape values read out from the waveshape memory is caused to circulate at a predetermined rate of time in the loop circuit. A waveshape taken out from the loop circuit varies as time lapses, and is utilized as a musical tone.

Abstract: A digital type electronic musical instrument generates a tone signal consisting of a plurality of time-varying partial tone signals each by recursive calculation. A recursive calculator is of a simplified construction by arranging the amplitude term to be excluded from the recursive calculation and to be multiplied thereafter. A remarkable reduction in the memory units can be accomplished by arranging the pair of initial values for each partial tone function to be equal to each other by the introduction of a phase term into the periodic part of the partial tone function.