Envelope control system for electronic musical instrument

Claim 2

In an electronic musical instrument in which periodic function data such as sine or cosine wave data is read out from a waveform memory according to a note frequency for forming a musical sound signal, an envelope control system for the electronic musical instrument comprising reading means (4, 4a) for reading out two periodic function waveforms at the same frequency but having different phases from at least one waveform memory (7, 7a), means (5, 5a, 6-0 to 6-11) for changing the phase of at least one of said two read-out waveforms according to a given envelope, and means (8, 8a, 10, 10a) for combining said two read-out waveform data to obtain an envelope controlled resultant waveform data.

Claim 3

The envelope control system according to claim 1, wherein said data read-out means (4, 4a) includes means (2, 3, 3a) for forming frequency data according to a key code from a keyboard (1), and an adder (4, 4a) having a first input terminal group (AO to A12) to which the frequency data is supplied and a second input terminal group (BO to B12) to which envelope data is supplied.

Claim 4

The envelope control system according to claim 2, wherein said phase changing means. (5, 5a, 6-0 to 6-11) includes AND gate means (6-0 to 6-5) for supplying envelope data to said second input terminal group (BO to B5) according to a clock signal (¢), whereby said two waveforms are read out on a time division basis.

Claim 5

The envelope control system according to claim 1, wherein said phase changing means (5, 5a, 6-0 to 6-11) makes the two waveforms to have the same frequencies and phases oppositely phase-shifted by the same amount.

Claim 6

The envelope control system according to claim 2, wherein said phase changing means (5, 5a, 6-0 to 6-11) includes exclusive OR gate means (6-0 to 6-11) for supplying envelope data of alternately opposite polarities to said second input terminal group (BO to B5) according to alternate "1" and "0" levels of the clock signal to thereby permit reading of said two waveforms on a time division basis, and also wherein said adder (4, 4a) includes a carry input terminal (Cin) to which a carry signal is supplied when polarity inversion envelope data is supplied to the second input terminal group (BO to B5), and means for providing sum data as an address signal for reading out two waveforms at the same frequency and oppositely phase shifted by the same amount from a waveform memory (7, 7a).

Claim 7

The envelope control system according to claim 4 or 5, wherein said phase changing means (5, 5a, 6-0 to 6-11) includes means for making the rate of change of phase shift of said two waveforms non-uniform.

Claim 8

The envelope control system according to claim 6, wherein said non-uniform making means serves to approximate a function waveform with a plurality of straight line segments, make the rate of change of the phase shift non-uniform so as to obtain downwardly convex exponential curves for the approximation straight line segments and change the rate of change of. the phase shift for each of said approximation straight line segments.

Claim 9

The envelope control system according to claim 6 or 7, wherein said electronic musical instrument is further provided with means for correcting the non-uniform rate of change of the phase shift provided by said non-uniform making means to a constant rate for the attack portion of the envelope.

Claim 10

The envelope control system according to either one of claims 1 to 3, wherein said reading means reads out sin2π( ) (2n being the total number of sampling points and "a" being the order number of the sampling point of reading) as the first waveform and sin2n( ) (b being data representing phase difference) as the second waveform from said waveform memory and said synthesizing means provides 2sin (a + ) cos · as the resultant output.

Claim 11

The envelope control system according to either one of claims 1 to 3, wherein said reading means reads out sin2π( ) (2n being the total number of sampling points and "a" being the order number of the sampling point of reading) as the first waveform and sin2π( ) (b being data representing phase difference) as the second waveform from said waveform memory and said synthesizing means provides -2cos (a + ) sin · or 2cos (a + ) sin · as the resultant output.

Claim 12

The envelope control system according to either one of claims 1 to 3, wherein said reading means reads out cos2π( ) (2 n being the total number of sampling points and "a" being the order number of the sampling point of reading) as the first waveform and cos2π ( ) (b being data representing phase difference) as the second waveform from said waveform memory and said synthesizing means provides 2cos (a+ )cos · as the resultant output.

Claim 13

The envelope control system according to either one of claims 1 to 3, wherein said reading means reads out cos2π( ) (2 n being the total number of sampling points and "a" being the order number of the sam - pling point of reading) as the first waveform and cos2π( ) (b being data representing phase differ- ence) as the second waveform and said synthesizing means provides 2sin (a+ ) sin · or -2sin (a + ) sin · as the resultant out- put.

Claim 14

The envelope control system according to either one of claims 1 to 7, wherein said reading means reads out sin2π( ) (2 n being the total number of sampling points, "a" being the order number of sampling points of reading as the first waveform and b being data representing the magnitude of phase shift) as the first wavefrom and sin2π( ) or sin2π( ) as the second waveform and said synthesizing means reads out 2sin acos b or 2cos asin b as the resultant output.

Claim 15

The envelope control system according to either one of claims 1 to 7, wherein said reading means reads sin2π( ) (2 n being the total number of sam- pling points, "a" being the order number of sampling point of reading and b being data representing the magnitude of the phase shift) as the first waveform and sin2nπ( ) or sin2π( ) as the second waveform from said waveform memory and said synthesizing means produces 2cos asin b, -2cos asin b, 2sin acos b or -2si acos b as the resultant output.

Claim 16

The envelope control system according to either one of claims 1 to 7, wherein said reading means reads out cos2π( ) (2 n being the total number of sampling points, "a" being the ordr number of sampling point of reading and b representing the magnitude of phase difference) as the first waveform and cos2π( as the second waveform from said waveform memory and said synthesizing means produces 2cos acos b as the resultant output.

Claim 17

The envelope control system according to either one of claims 1 to 7, wherein said reading means . reads out cos2π( ) (2 n being the total number of sampling points, "a" being the order number of sampling point of reading and b being data representing the magnitude of phase difference) as the first waveform and cos2π( ) as the second waveform from said wave- form memory and said synthesizing means produces either -2sin asin b or 2sin asin b as the resultant output.

Claim 18

An electronic musical instrument comprising frequency data generating means for generating frequency data corresponding to a given note for each of a plurality of time division basis proces channels, fundamental sound address specifying means for specifying the phase address for fundamental sound according to frequency data provided for each channel from said frequency data generating means, harmonic sound address specifying means for specifying the phase address of a harmonic of a given order in a time division basis process in each channel according to the phase address for the fundamental sound specified by said fundamental sound address specifying means, a waveform memory for a sine wave (or cosine wave), envelope data generating means for generating envelope data corresponding to the fundamental sound and harmonic sounds in each of said channels, and reading means for reading two sine waves (or cosine waves) at the same frequency and phase shifted in opposite directions by the same amount according to said envelope data in a time division basis from said waveform memory for the fundamental sound and harmonic sounds in each of said channels according to the phase address data of said fundamental sound address specifying means and harmonic sound address specifying means, said individual means being each operated on a time division basis, thereby permitting production of a chord sound containing a plurality of harmonic musical sounds of given orders.

Claim 19

An electronic musical instrument comprising frequency data generating means for generating frequency data corresponding to a given note for each of a plurality of time division basis proces channels, fundamental sound address specifying means for specifying the phase address for fundamental sound according to frequency data provided for each channel from said frequency data generating means, harmonic sound address specifying means for specifying the phase address of a harmonic of a given order in a time division basis process in each channel according to the phase address for the fundamental sound specified by said fundamental sound address specifying means, a waveform memory for a sine wave (or cosine wave), envelope data generating means for generating envelope data corresponding to the fundamental sound and harmonic sounds in each of said channels, and reading means for reading two sine waves (or cosine waves) at the same frequency and phase shifted in opposite directions by the same amount according to said envelope data in a time division basis from said waveform memory for the fundamental sound and harmonic sounds in each of said channels according to the phase address data of said fundamental sound address specifying means and harmonic sound address specifying means, said individual means being each operated on a time division basis, thereby permitting production of a chord sound containing a plurality of harmonic musical sounds of given orders.

Claim 20

An electronic musical instrument comprising musical sound generating means including a plurality of LSI chips capable of producing the fundamental sound and harmonic sounds of given orders with respect to said fundamental sound for a plurality of musical sounds by reading out a sine wave (or cosine wave), and control means for assigning given musical sounds to the individual LSI chips of said musical sound generating means and setting the order of harmonic sounds with respect to the fundamental sound, whereby a chord sound containing a plurality of component musical sounds including harmonic sounds of given orders can be produced.

Claim 21

An electronic musical instrument comprising musical sound generating means including a plurality of LSI chips capable of producing the fundamental sound and harmonic sounds of given orders with respect to said fundamental sound for a plurality of musical sounds by reading out a sine wave (or cosine wave), and control means for assigning given musical sounds to the individual LSI chips of said musical sound generating means and setting the order of harmonic sounds with respect to the fundamental sound, whereby a chord sound containing a plurality of component musical sounds including harmonic sounds of given orders can be produced.

Claim 22

The electronic musical instrument according to claim 18, wherein said LSI chips are capable of producing the fundamental sound and harmonic sounds of given orders with respect to said fundamental sound for a plurality of musical sounds through a time division basis treatment.