Electronic musical instrument with improved capability for simulating an actual musical instrument

• US 5,164,530 A
• Filed: 12/27/1989
• Issued: 11/17/1992
• Est. Priority Date: 12/29/1988
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Iwase, Hiroshi
• Primary Examiner(s): Witkowski, Stanley J.
• Application Number:
  US07/457,512
• Time in Patent Office: 1,056 Days
• Field of Search: 84/615, 84/622-627, 84/633, 84/658-661, 84/663, 84/665, 84/687-690, 84/692-700, 84/702, 84/703, 84/711, 84/477 R, 84/478, 84/708 , 84/DIG. 1, 84/DIG. 27
• US Class Current: 84/624
• CPC Class Codes: G10H 1/053 during execution only voice controlled instruments G10H5/005
• CPC Class Codes: Y10S 84/27 Stereo

Abstract

A musical sound waveform generator includes a carrier signal generating unit, a modulation signal generating unit, a mixing controlling unit and a waveform outputting unit. The characteristics of the carrier signal from the carrier signal generating unit are determined such that the musical sound waveform generated by the waveform outputting unit is a sine wave or a cosine wave with a single frequency, where the mixing ratio of the modulation signal is made 0 by the mixing controlling unit. Therefore, the mixing controlling unit presets the mixing ratio of the modulation signal to be 0, making it possible to generate a musical sound waveform which is only a sine wave or a cosine wave of a single frequency. During the performance, the mixing ratio can, for example, be determined at a high value immediately after the start of sound generation and thereafter reduced to near 0 with time. Thereby, the frequency characteristics of the musical sound waveform can be controlled such that the musical sound waveform is changed from one having a lot of higher harmonics to one having only a single sine wave component or a single cosine wave component.

Claims

1. A musical sound waveform generator for generating a musical sound waveform according to a mixed signal obtained by mixing a modulation signal with a carrier signal, comprising:

a carrier signal generating means for generating a carrier signal,

a modulation signal generating means for generating a modulation signal,

a mixing controlling means for outputting a mixed signal X obtained by mixing said modulation signal with said carrier signal and for controlling the mixing ratio of said modulation signal to said carrier signal from 0 to a discretional mixing ratio, and

a waveform outputting means, having a predetermined function relationship between input and output thereof, for outputting a musical sound waveform according to said mixed signal X received as an input signal from said mixing controlling means, wherein

said predetermined function relationship in said waveform outputting means is neither a sine function nor a cosine function and said carrier signal generated by said carrier signal generating means is such that said musical sound waveform generated by said waveform outputting means is a sine wave or a cosine wave with a single frequency, where the mixing ratio of said modulation signal to said carrier signal is set to 0 by said mixing controlling means.

2. The musical sound waveform generator according to claim 1, wherein

said carrier signal generating means receives a carrier wave phase angle ω

_ct, which increases at a constant angular speed and outputs a carrier signal W_C, given by the following equations

space="preserve" listing-type="equation">W.sub.C =(π

/2) sin ω

.sub.ct . . . (0≦

ω

.sub.ct ≦

π

/2)

space="preserve" listing-type="equation">W.sub.C =π

-(π

/2) sin ω

.sub.ct . . . (π

/2≦

ω

.sub.ct ≦

3π

/2)

space="preserve" listing-type="equation">W.sub.C =2π

+(π

/2) sin ω

.sub.ct . . . (3π

/2≦

ω

.sub.ct ≦

2π

),

and

said waveform outputting means outputs a musical sound waveform D when receiving said mixed signal x as an input, said waveform D being based on the following equations

space="preserve" listing-type="equation">D=(2/π

) x . . . (0≦

x≦

π

/2)

space="preserve" listing-type="equation">D-1+(2/π

)(3π

/2-x) . . . (π

/2≦

x≦

3π

/2)

space="preserve" listing-type="equation">D=-1+(2/π

)(x-3π

/2) . . . (3π

/2≦

x≦

2π

).

3. The musical sound waveform generator according to claim 1, wherein

said carrier signal generating means receives a carrier wave phase angle ω

_ct, which increases at a constant angular speed and outputs a carrier signal W_C, given by the following equations

space="preserve" listing-type="equation">W.sub.C =(π

/4) sin ω

hd ct . . . (0≦

ω

.sub.ct ≦

π

/2)

space="preserve" listing-type="equation">W.sub.C =-(π

/4) sin ω

.sub.ct +π

. . . (π

/2≦

ω

.sub.ct ≦

3π

/2)

space="preserve" listing-type="equation">W.sub.C =(π

/4) sin ω

.sub.ct +2π

. . . (3π

/2≦

ω

.sub.ct ≦

2π

),

and

said waveform outputting means outputs a musical sound waveform D when receiving said mixed signal x as an input, said waveform D being based on the following equations

space="preserve" listing-type="equation">D=(4/π

) x . . . (0≦

x≦

π

/4)

space="preserve" listing-type="equation">D=1 . . . (π

/4≦

x≦

3π

/4)

space="preserve" listing-type="equation">D=-(4/π

) x+4 . . . (3π

/4≦

x≦

5π

/4)

space="preserve" listing-type="equation">D=-1 . . . (5π

/4≦

x≦

7π

/4)

space="preserve" listing-type="equation">D=(4/π

) x-8 . . . (7π

/4≦

x≦

2π

).

4. The musical sound waveform generator according to claim 1, wherein

said carrier signal generating means receives a carrier wave phase angle ω

_ct, which increases at a constant angular speed and outputs a carrier signal W_C, given by the following equations

space="preserve" listing-type="equation">W.sub.C =ω

.sub.ct /2 . . . (0≦

ω

.sub.ct ≦

π

/2)

space="preserve" listing-type="equation">W.sub.C ω

.sub.ct /2+π

/2 . . . (π

/2≦

ω

.sub.ct ≦

3π

/2)

space="preserve" listing-type="equation">W.sub.C =ω

.sub.ct /2+π

. . . (3π

/2≦

ω

.sub.ct ≦

2π

),

and

said waveform outputting means outputs a musical sound waveform D when receiving said mixed signal x as an input, said waveform D being based on the following equations (sin designates a sine wave arithmetic operation)

space="preserve" listing-type="equation">D=sin 2x . . . (0≦

x≦

π

/4)

space="preserve" listing-type="equation">D=1 . . . (π

/4≦

x≦

3π

/4)

space="preserve" listing-type="equation">D=sin (2x-π

) . . . (3π

/4≦

x≦

5π

/4)

space="preserve" listing-type="equation">D=-1 . . . (5π

/4≦

x≦

7π

/4)

space="preserve" listing-type="equation">D=sin (2x-2π

) . . . (7π

/4≦

x≦

2π

).

5. The musical sound waveform generator according to claim 1, wherein

said carrier signal generating means receives a carrier wave phase angle ω

_ct, which increases at a constant angular speed and outputs a carrier signal W_C, given by the following equations

space="preserve" listing-type="equation">W.sub.C =ω

.sub.ct . . . (0≦

ω

.sub.ct ≦

π

/2)

space="preserve" listing-type="equation">W.sub.C ≦

-(π

/2) sin ω

.sub.ct +π

. . . (π

/2≦

ω

.sub.ct ≦

3π

/2)

space="preserve" listing-type="equation">W.sub.C≦

ω

.sub.ct . . . (3π

/2≦

ω

.sub.ct ≦

2π

),

and

said waveform outputting means outputs a musical sound waveform D when receiving said mixed signal x as an input, said waveform D being based on the following equations

space="preserve" listing-type="equation">D=sin x . . . (0≦

x≦

π

/2)

space="preserve" listing-type="equation">D=-(2/π

) x+2 . . . (π

/2≦

x≦

3π

/2)

space="preserve" listing-type="equation">D=sin x . . . (3π

/2≦

x≦

2π

).

6. The musical sound waveform generator according to claim 1, wherein

said carrier signal generating means receives a carrier wave phase angle ω

_ct, which increases at a constant angular speed and outputs a carrier signal W_C, given by the following equations

space="preserve" listing-type="equation">W.sub.C =(π

/2) sin ω

.sub.ct . . . (0≦

ω

.sub.ct ≦

π

/2)

space="preserve" listing-type="equation">W.sub.C =ω

.sub.ct . . . (π

/2≦

ω

.sub.ct ≦

3π

/2)

space="preserve" listing-type="equation">W.sub.C =(π

/2) sin ω

.sub.ct +2π

. . . (3π

/2≦

ω

.sub.ct ≦

2π

),

and

said waveform outputting means outputs a musical sound waveform D when receiving said mixed signal x as an input, said waveform D being based on the following equations

space="preserve" listing-type="equation">D=(2/π

) x . . . (0≦

x≦

π

/2)

space="preserve" listing-type="equation">D=sin x . . . (π

/2≦

x≦

3π

/2)

space="preserve" listing-type="equation">D=(2/π

) x-4 . . . (3π

/2≦

x≦

2π

).

7. The musical sound waveform generator according to claim 1, further comprising a mixing ratio controlling means for varying with time the mixing ratio of said modulation signal to said carrier signal, used by said mixing control means, after the start of sound generation of said musical sound waveform.

8. The musical sound waveform generator according to claim 1, further comprising an amplitude envelope controlling means for changing with time the amplitude envelope characteristics of said musical sound waveform outputted from said waveform outputting means.

9. The musical sound waveform generator according to claim 1, wherein

said carrier signal generating means, said modulation signal generating means, said mixing control means and said waveform outputting means perform a time divisional process on a plurality of sound generating channels and polyphonically output a plurality of musical sound waveforms assigned to corresponding sound generating channels.

10. A musical sound waveform generator according to claim 1, further comprising a random controlling means for performing a control so that at least one of said carrier signals generated by said carrier signal generating means, said modulation signal generated by said modulation signal generating means or said mixing ratio controlled by said mixing controlling means includes a component which varies randomly.

11. The musical sound waveform generator according to claim 1, further comprising a random controlling means for performing a control so that at least one of said carrier signal, said modulation signal and said mixing ratio includes a component which varies randomly within a predetermined time period after the start of generation of said musical sound waveform.

12. The musical sound waveform generator according to claim 11, wherein

said predetermined time period is one of an attack period, an decay period, an sustain period or a release period in the amplitude envelope characteristics of said musical sound waveform.

13. The musical sound waveform generator according to claim 11, further comprising an amplitude envelope random controlling means for performing a control such that the amplitude envelope characteristics of said musical sound waveform outputted from said waveform outputting means includes a component which varies randomly within a predetermined time period after the start of generation of said musical sound waveform.

14. A musical sound waveform generating method for generating a musical sound waveform according to a mixed signal obtained by mixing a modulation signal with a carrier signal, comprising the steps of:

generating a carrier signal,

generating a modulation signal,

outputting a mixed signal obtained by mixing said modulation signal with said carrier signal and controlling the mixing ratio of said modulation signal to said carrier signal from 0 to a discretional mixing ratio, and

outputting a musical sound waveform according to said mixed signal provided as an input signal to a predetermined function relationship between an input and an output, wherein

said predetermined function relationship is neither a sine function nor a cosine function and said carrier signal is such that said musical sound waveform is a sine wave or a cosine wave with a single frequency, where the mixing ratio of said modulation signal to said carrier signal is set to 0.

15. A musical sound waveform generator for generating a musical sound waveform according to a mixed signal obtained by mixing a modulation signal with a carrier signal and for controlling a characteristic of said musical sound waveform based on performance information generated in accordance with a performance operation, comprising:

a carrier signal generating means for generating a carrier signal corresponding to said performance information,

a modulation signal generating means for generating a modulation signal corresponding to said performance information,

a mixing controlling means for outputting a mixed signal obtained by mixing said modulation signal with said carrier signal and for controlling the mixing ratio of said modulation signal to said carrier signal so that it varies in accordance with mixing characteristics corresponding to said performance information, and

a waveform outputting means, having a predetermined function relationship between input and output thereof, for outputting a musical sound waveform according to said mixed signal received as an input signal from said mixing controlling means, wherein

said predetermined function relationship in said waveform outputting means is neither a sine function nor a cosine function and said carrier signal is such that said musical sound waveform generated by said waveform outputting means is a sine wave or a cosine wave with a single frequency, where the mixing ratio of said modulation signal to said carrier signal is set to 0 by said mixing controlling means.

16. The musical sound waveform generator according to claim 15, wherein

said performance operation is a key depression operation of a keyboard, and

said mixing controlling means controls said mixing characteristics so that they correspond to at least one of a speed of said key depression operation or an area of the keyboard in which said key is depressed.

17. The musical sound waveform generator according to claim 15, further comprising an amplitude envelope controlling means for changing with time the amplitude envelope characteristics of said musical sound waveform outputted from said waveform outputting means to correspond to said performance information.

18. The musical sound waveform generator according to claim 15, wherein

said carrier signal generating means, said modulation signal generating means, said mixing control means and said waveform outputting means perform a time divisional process on a plurality of sound generating channels and polyphonically output a plurality of musical sound waveforms assigned to corresponding sound generating channels.

19. A musical sound waveform generator for generating a musical sound waveform according to a mixed signal obtained by mixing a modulation signal with a carrier signal, comprising:

a carrier signal generating means for generating a carrier signal,

a modulation signal generating means for selectively generating plural kinds of modulation signals,

a mixing controlling means for outputting a mixed signal obtained by mixing said selectively generated modulation signal with said carrier signal and for controlling the mixing ratio of said modulation signal to said carrier signal from 0 to a discretional mixing ratio, and

a waveform outputting means, having a predetermined function relationship between an input and an output thereof, for outputting a musical sound waveform according to said mixed signal received as an input signal from said mixing controlling means, wherein

said predetermined function relationship in said waveform outputting means is neither a sine function nor a cosine function and said carrier signal generated by said carrier signal generating means is such that said musical sound waveform generated by said waveform outputting means is a sine wave or a cosine wave with a single frequency, where the mixing ratio of said modulation signal to said carrier signal is set to 0.

20. The musical sound waveform generator according to claim 19, wherein

said modulation signal generating means further comprises:

a storing means for storing plural kinds of modulation functions beforehand,

a selecting means for selecting one of said plural kinds of modulation functions stored in said storing means, and

an outputting means for generating a modulation wave corrected phase angle signal by converting the inputted modulation wave phase angle signal by a modulation function selected by said selecting means and by further converting the modulation wave corrected phase angle signal based on a triangular wave function, thereby generating said modulation signal.

21. The musical sound waveform generator according to claim 19, further comprising an amplitude envelope controlling means for changing with time the amplitude envelope characteristic of said musical sound waveform outputted from waveform outputting means.

22. The musical sound waveform generator according to claim 19, wherein

said carrier signal generating means, said modulation signal generating means, said mixing control means and said waveform outputting means perform a time divisional process on a plurality of sound generating channels and polyphonically output a plurality of musical sound waveforms assigned to corresponding sound generating channels.

23. A musical sound waveform generator for generating a musical sound waveform according to a mixed signal obtained by stereophonically mixing a modulation signal with a carrier signal, comprising:

a carrier signal generating means for generating a carrier signal,

a modulation signal generating means for generating a modulation signal,

a mixing means for outputting a mixed signal obtained by mixing said modulation signal with said carrier signal,

a mixing ratio controlling means for varying the mixing ratio of said modulation signal to said carrier signal from 0 to a discretional mixing ratio,

a waveform outputting means, having a predetermined function relationship between input and output thereof, for outputting a musical sound waveform according to said mixed signal received as an input signal from said mixing means, and

a time divisional controlling means for performing a time divisional control of said carrier signal generating means, said modulation signal generating means and said mixing ratio controlling means so that at least one of them generates values which are different between respective stereo channels, and inputting mixed signals of respective stereo channels from said mixing means at respective time divisional timings based on said time divisional control to said waveform outputting means, thereby outputting respective musical sound waveforms modulated independently for respective stereo channels, wherein

said predetermined function relationship in said waveform outputting means is neither a sine function nor a cosine function and said carrier signal generated by said carrier signal generating means is such that said musical sound waveform generated by said waveform outputting means is a sine wave or a cosine wave with a single frequency, where the mixing ratio of said modulation signal to said carrier signal is set to 0 by said mixing ratio controlling means.

24. The musical sound waveform generator according to claim 23, further comprising an amplitude envelope controlling means for varying with time the amplitude envelope characteristics of respective musical sound waveforms independently outputted from said waveform outputting means for respective stereo channels so that the respective amplitude envelope characteristics are different between respective stereo channels.

25. The musical signal waveform generator according to claim 23, wherein

said carrier signal generating means, said modulation signal generating means, said mixing means, said mixing ratio controlling means, said waveform outputting means, and said time divisional controlling means perform a time divisional process by dividing said respective stereo channels further into a plurality of sound generating channels and stereophonically and polyphonically output a plurality of musical sound waveforms assigned to corresponding sound generating channels.

26. A musical sound waveform generator generating a musical sound waveform according to a mixed signal obtained by mixing a modulation signal with a carrier signal and for controlling a characteristics of said musical sound waveform based on performance information generated in accordance with a performance operation, comprising:

a carrier signal generating means for generating a carrier signal,

a modulation signal generating means for generating a modulation signal,

a mixing controlling means for outputting a mixed signal obtained by mixing said modulation signal with said carrier signal and for controlling the mixing ratio of said modulation signal to said carrier signal from 0 to a discretional mixing ratio,

a waveform outputting means, having a predetermined function relationship between an input and an output thereof, for outputting a musical sound waveform according to said mixed signal received as an input signal from said mixing controlling means, and

a frequency ratio controlling means for performing a control such that the frequency ratio of said modulation signal to said carrier signal corresponds to said performance information, wherein

said predetermined function relationship in said waveform outputting means is neither a sine function nor a cosine function and said carrier signal generated by said carrier signal generating means is such that said musical sound waveform generated by said waveform outputting means is a sine wave or a cosine wave with a single frequency, where the mixing ratio of said modulation signal to said carrier signal is made 0 by said mixing controlling means.

27. The musical sound waveform generator according to claim 26, wherein

said frequency ratio controlling means controls said frequency ratio in accordance with the timbre of said musical sound waveform.

28. The musical sound waveform generator according to claim 26, wherein

said performance operation is a depression of a key on a keyboard, and

said frequency ratio controlling means controls said frequency ratio so that it corresponds to at least one of key depression speed and the area of the keyboard at which said depressed key is located.

29. A musical sound waveform generator for generating a musical sound waveform according to a mixed signal obtained by mixing a modulation signal with a carrier signal, comprising:

a carrier signal generating means for generating a carrier signal,

a modulation signal generating means for generating a modulation signal,

a mixing controlling means for outputting a mixed signal obtained by mixing said modulation signal with said carrier signal and for controlling the mixing ratio of said modulation signal to said carrier signal, and

a waveform outputting means, having a predetermined function relationship between an input and an output thereof, for outputting a musical sound waveform according to said mixed signal received as an input signal from said mixing controlling means, wherein

said predetermined function relationship in said waveform outputting means is neither a sine function nor a cosine function, and is determined such that one of a sine wave and a cosine wave with a single frequency is outputted from the waveform outputting mean when the mixing ratio is a predetermined value, and wave shapes of said carrier signal and said modulation signal are specified ones.