Electronic musical instrument

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. The increasing accumulated value is used to address the waveform memory device to read out therefrom amplitude samples to form a desired musical tone wave form. The output of the waveform memory means is imparted with a volume envelope generated by an envelope waveform generator and then produced as a performance tone by a sound system.

What is claimed is: 
     
       1. An electronic musical instrument comprising a keyboard provided with a plurality of keys for respective tone pitches, means for generating a plurality of frequency informations corresponding to the tone pitch of depressed one of said keys, selecting means for selecting one at a time of said plurality of frequency informations produced by said frequency information generating means, accumulating means for repeatedly accumulating the frequency information selected by said selecting means to produce a progressing accumulated value, a waveform memory device which is adapted to store amplitude values at successive sampling points in one period of a waveform utilized to form a desired musical waveform and which is addressed with said progressing accumulated value from the accumulating means, control means for switching the selecting operation of said selecting means during the accumulating operation of said accumulating means to select different ones time wisely from among said plurality of frequency informations, and means for converting said musical tone waveform read out from said waveform memory device into a musical tone. 
     
     
       2. An electronic musical instrument according to claim 1 wherein said control means comprises a detector which detects the fact that said accumulated value has reached a predetermined value for controlling the switching of said selecting means. 
     
     
       3. An electronic musical instrument according to claim 1 wherein said control means comprises means responsive to a predetermined number of accumulations for controlling the switching of said selecting means. .Iadd. 4. An electronic musical instrument comprising: a keyboard provided with a plurality of keys for respective tone pitches,   means for providing a plurality of frequency informations in accordance with the tone pitch of a depressed one of said keys,   selecting means for selecting one at a time which of said plurality of frequency informations is provided by said frequency information generating means,   arithmetic operation means responsive to the frequency information selected by said selecting means for producing an address signal by carrying out repetitive arithmetic operations utilizing said selected frequency information, said produced address signal varying at a rate corresponding to the selected frequency information,   a waveform memory device which is adapted to store amplitude values at successive sampling points in one portion of a waveform utilized to form a desired musical waveform and which is addressed with said address signal from the arithmetic operation means,   control means for switching the selecting operation of said selecting means during the operation of said arithmetic operation means to select different ones time wisely from among said plurality of frequency informations, and   means for converting said musical tone waveform read out from said waveform memory device into a musical tone. .Iaddend. .Iadd. 5. An electronic musical instrument according to claim 4 in which said control means responds to said address signal to detect when the address signal is in a predetermined state thereby switching the selecting operation of said selecting means in accordance with the address signal. .Iaddend. .Iadd. 6. In an electronic musical instrument having a keyboard provided with a plurality of keys for respective tone pitches, each key being represented by a key code, the improvement comprising:   means for providing a plurality of frequency informations in accordance with the key code of a depressed one of said keys,   selecting means for selecting one at a time which of said plurality of frequency informations is provided by said frequency information generating means,   accumulated value means for repeatedly utilizing the frequency information selected by said selecting means to produce progressively changing accumulated values,   a waveform memory device which is adapted to store amplitude values at successive sampling points in one portion of a waveform utilized to form a desired musical waveform and which is addressed with said progressing accumulated values from the accumulated value means,   control means for switching the selecting operation of said selecting means during the operation of said accumulated value means to select different ones time wisely from among said plurality of frequency informations, and   means for converting said musical tone waveform read out from said waveform memory device into a musical tone. .Iaddend. .Iadd. 7. In an electronic musical instrument of the type in which a waveform memory device stores values indicative of musical waveform amplitudes at successive sample points, and in which said values are repetitively read out from the memory device and converted to a musical tone, the improvement comprising:   means for providing first and second tone frequency related constants,   a counter having a modulo corresponding to the number of sample point values stored in said waveform memory device, the contents of said counter being used as an address signal to read out said waveform memory device,   means for repetitively utilizing a supplied one of said first or second frequency related constants to cause incrementing of said counter at a rate established by the value of the utilized frequency constant, so that the accumulated contents of said counter constitutes an address signal that changes progressively at a rate established by the utilized frequency constant,   selector means, connected to said counter and responsive to the accumulated contents thereof, for causing one or the other of said first and second provided frequency related constants to be supplied to said means for utilizing in accordance with a comparison between the accumulated contents of said counter and a certain change point value. .Iaddend..Iadd. 8. An electronic musical instrument according to claim 7 wherein said frequency related constants are in binary format, and further having:   a shift circuit, cooperating with said selector means, for shifting said provided frequency related constants by a degree in accordance with the octave of a selected note. .Iaddend.