Electronic musical instrument forming tone waveforms

Abstract

A frequency number corresponding to the frequency of a tone intended to be sounded is accumulated in an accumulator at every calculation timing of a constant interval to produce values progressing at a rate corresponding to the tone frequency. At this rate, waveform amplitude value samples are sequentially produced one after another in a tone producing section using the output of the accumulator as phase angle data. A reset circuit is provided in connection with the accumulator and this circuit functions to compulsorily reset the progressing values in the accumulator to its initial value in response to a carry out signal generated at the calculation timing when the phase angle data has reached its predetermined modulo value. Thus the period of progress of the phase angle data is harmonized with the calculation timing, i.e., the sampling timing. As a result, the frequency of a tone waveform signal, whatever it may be, can be harmonized with the sampling frequency while the interval of the respective sampling timing is maintained constant.

I claim: 
     
       1. An electronic musical instrument comprising: a phase angle data generator for generating a phase angle data signal which exhibits a value timewisely progressing, at every predetermined sampling timing of a constant interval, from a first value to a second value at an incremental step value per timing interval corresponding to the frequency of a tone intended to be sounded;   a reset circuit connected to said phase angle data generator for resetting the progressing value of said phase angle data signal to said first value at each sampling timing that said data reaches said second value; and   a tone generator connected to said phase angle data generator for generating a tone signal based on the progressing value of said phase angle data signal.   
     
     
       2. An electronic musical instrument as defined in claim 1 wherein: said phase angle data generator comprises an accumulator having a modulo of a value equal to said second value which repeatedly adds or subtracts, at a calculation timing of a constant interval, a constant corresponding to the frequency of the tone intended to be sounded; and   said reset circuit resets to said first value, at each timing at which a carry out signal is produced by said accumulator, a progressing value which has caused said accumulator to produce the carry out signal.   
     
     
       3. An electronic musical instrument as defined in claim 2 wherein said constant includes a first constant representing a note within one octave and a second constant representing an octave among plural octaves;   said accumulator includes a first accumulator having a modulo of a third value which repeatedly adds or subtracts said first constant at a predetermined calculation timing and a second accumulator having a modulo of a value equal to said second value which repeatedly adds or subtracts said second constant each time a first carry out signal is produced by said first accumulator; and   said reset circuit resets, upon production of a second carry out signal by said second accumulator, respective progressing values which have caused said first and second accumulators to produce said first and second carryt out signals.   
     
     
       4. An electronic musical instrument as defined in claim 1 which further comprises note selection means for selecting a note from among a plurality of notes and a key assigner for assigning the note selected by said note selection means to one of a plurality of tone genertion channels; and wherein said phase angle data generator generates, on a time shared basis, the phase angle data signal progressing at a rate corresponding to the frequency of said note having been assigned to said channel at every sampling timing of a constant interval arriving on a time shared basis for each of the tone generation channels;   said reset circuit resets, upon reaching of the phase angle data signal to said second value at a sampling timing of a certain channel, only the progressing value of the phase angle data signal corresponding to this channel in said phase angle data generator; and   said tone generator produces tone signals in a plurality of channels in response to the phase angle data signal provided on a time shared basis by said phase angle data generator.   
     
     
       5. An electronic musical instrument comprising: a phase angle data generator for generating a phase angle data signal which exhibits a value timewisely progressing, at every predetermined sampling timing of a constant interval, from a first value to a second value at a rate corresponding to the frequency of a tone intended to be sounded;   a reset circuit connected to said phase angle data generator for resetting the progressing value of said phase angle data signal to said first value at every sampling timing when said data reaches said second value;   first memory means for temporarily storing the phase angle data signal produced by said phase angle data generator after sampling it at a low speed timing;   a tone generator for generating tone waveform amplitude data based on the progressing value of said phase angle data signal stored in said first memory means;   second memory means for temporarily storing the tone waveform amplitude data generated by said tone generator after sampling it at a high speed timing; and   third memory means for storing said tone waveform amplitude data of said second memory means at every sampling timing at which the phase angle data in said phase angle data generator exhibits a predetermined third value;   the output of said third memory means being used as a tone signal.   
     
     
       6. An electronic musical instrument as defined in claim 5 wherein said phase angle data generator comprises a first accumulator having a modulo of a third value which repeatedly adds or subtracts a first constant corresponding to a note of the tone to be sounded within one octave and a second accumulator which adds or subtracts a second constant corresponding to the octave of the tone to be sounded each time a first carry out signal is produced by said first accumulator;   said reset circuit resets, upon production of a second carry out signal by said second accumulator, respective progressing values which have caused said first and second accumulators to produce said first and second carry out signals; and   said third memory means having said tone waveform amplitude data of said second memory means loaded therein each time said first carry out signal is produced by said first accumulator.   
     
     
       7. An electronic musical instrument comprising: a keyboard;   a depressed key detector;   key assigner means for generating, in time division order, codes identifying depressed keys;   frequency number table means for generating, in like time division order, frequency numbers corresponding to depressed key identified by said codes;   operating means for generating, in like time division order, phase data of waveshapes on the basis of said frequency numbers;   channel timing speed high/low converter means for sampling said phase data at a timing which is slower than the timing of said time division order, thereby converting said phase data to a relatively lower sampling speed;   tone production means for generating a waveshape in response to said phase data sampled at said lower speed;   first and second shift registers each having a number of stages equal to the maximum number of tones to be sounded simultaneously and shifted at a relatively higher speed corresponding to said time division order;   channel timing speed low/high converter means for loading the generated waveshape into a corresponding channel of said first shift register;   selector means for selectively inputting to said second shift register either the output of said low/high converter means or the output of said second shift register respectively in accordance with a select signal provided by said operating means and representing a change of waveshape phase data in a corresponding time division channel; and   a sound system for producing a sound in response to the output of said second shift register.   
     
     
       8. An electronic musical instrument in which waveshape sample point amplitudes of a tone to be sounded are produced at certain regular time intervals, aliasing noise being eliminated in said instrument by harmonizing the frequency of said tone with the waveshape sampling frequency, comprising: phase angle data means for providing a repetitive phase angle data signal which exhibits a timewisely progressing value increasing stepwise at a certain relatively high speed timing clock rate, with an incremental step value corresponding to the frequency of said tone to be sounded, said signal being repetitively reset to a fixed value when a second value is reached, said resetting being synchronized with said high speed timing clock,   a tone production section for producing said sample point amplitudes but operating at a sampling frequency which is submultiple of said high speed timing clock rate,   a first channel timing speed converter at the input of said tone production section for sampling said phase angle data signal at said sampling frequency, the sampled values being input to said tone production section and utilized therein for the production of said sample point amplitudes, and   a second channel timing speed converter at the output of said tone production section for repetitively supplying the produced sample point amplitudes from said tone production section at said high speed timing clock rate, and   means for producing said sounded tone from the sample point amplitudes supplied from said second converter.   
     
     
       9. An electronic musical instrument according to claim 8 further comprising: synchronizing means, cooperating with said second converter, for causing a newly changed value of sample point amplitude from said tone production section to be supplied to said means for producing. .Iadd.   
     
     
       10.  In a time division multiplex polyphonic musical tone generation system for generating tones wherein waveshape samples corresponding to a tone are produced in time division order with respect to waveshape samples of other tones including non-harmonically related tones and each tone to be generated is assigned to a different time division multiplex time slot, the improvement for pitch synchronous tone generation comprising: storage means for storing and outputting, in time division order, waveshape samples corresponding to said tones assigned to the respective time slots; and   sampling means for sampling, at respective rates which are synchronous with the respective pitches of said selected tones assigned to the respective time slots, said waveshape samples outputted from said storage means at the respective time slots in said time division order. .Iaddend. .Iadd.   
     
     
       11.  The improvement as defined in claim 10 wherein said system has tone generation means for generating, in time division order according to a first rate, said waveshape samples corresponding to said tones assigned to the respective time slots, and wherein said storage means comprises: selection means for selecting said waveshape samples generated from said tone generation means in response to a predetermined timing clock signal; and   shift register means for circulatingly storing the selected waveshape samples in time division order according to a second rate. .Iaddend. .Iadd.   
     
     
       12.  The improvement as defined in claim 10 which further comprises: second storage means for storing, in time division order, said waveshape samples sampled by said sampling means. .Iaddend. .Iadd.   
     
     
       13.  An electronic musical instrument comprising: tone generating means for generating waveshape samples corresponding to tones in time division order with respect to waveshape samples of other tones including non-harmonically related tones and according to a first time division rate which is not synchronous with pitches of various tones to be generated, wherein each tone is assigned to a different tone generation channel;   pitch synchronous signal generation means for generating, in time division order according to a second time division rate and for each of the channels, a pitch synchronous signal which is synchronous with the pitch of the tone assigned to a corresponding one of the channels;   time division rate conversion means for converting the time division rate of the waveshape samples generated from said tone generation means from said first rate to said second rate; and   pitch synchronizing means for sampling, in time division order, the waveshape samples for each of the channels which have been converted to said second time division rate in accordance with the pitch synchronous signal corresponding to the channel thereby to provide, in time division order and for each of the channel, waveshape samples changing in synchronism with the pitch. .Iaddend. .Iadd.14. In a time division multiplex polyphonic musical tone generation system, wherein selected tones to be generated are assigned to different time division multiplex tone generation channels and tone waveform amplitude data for a tone is generated in time division order with respect to other tones including non-harmonically related tones, the improvement for harmonizing each change in tone waveform amplitude data with the phase of the corresponding generated tone, comprising:   storage means for storing and outputting, in time division order, tone waveform amplitude data corresponding to said tones assigned to the respective tone generation channels, and   sampling means for separately sampling, at respective rates which are synchronous with the phases of the respective pitches of said tones assigned to the respective tone generation channels, said tone waveform amplitude data outputted from said storage means at the respective tone generation channels in said time division order. .Iaddend. .Iadd.15. In an electronic musical instrument for generating tones and having plural time division multiplex tone generation channels and in which the tone waveform amplitude data of the respective plural tones are assigned to respective tone generation channels which are time division multiplexed with respect to each other, the improvement for synchronizing the change in the tone waveform amplitude data with the pitch of each respective tone while maintaining said data in the time division multiplex state, comprising:   first means for providing said tone waveform amplitude data including data for non-harmonically related tones respectively in the respective time division multiplexed tone generation channels,   second means for storing said tone waveform amplitude data in respective time division multiplexed channels and for providing said stored data in time division multiplex order for subsequent conversion to sound, and   sampling means for transferring individual tone waveform amplitude data from said first means to said second means in synchronism with the pitch of the respective tone assigned to the associated time division multiplex   
     
     
        tone generation channel. .Iaddend. .Iadd.16.  A tone signal generation device comprising: note clock generation means for generating note clock pulses corresponding to note name of a tone signal to be generated;   tone range data generation means for generating tone range data having a value representing a tone range to which said tone signal belongs;   phase angle data signal generation means for generating a phase angle data signal formed by performing processing of said tone range data at the timing of generation of said note clock pulse; and   waveshape generation means for generating a tone waveshape in the form of amplitude sample values in response to said phase angle data signal.   
     
     
        .Iaddend. .Iadd.17.  A tone signal generation device as defined in claim 16, wherein said tone range data corresponds to the difference between a tone pitch of said tone signal and a predetermined reference tone pitch. .Iaddend.