US3826859A - Electronic musical instrument with frequency-deviated pedal tone signal - Google Patents

Abstract

In an electronic musical instrument, a tone signal for the pedal keyboard is obtained by frequency-dividing the manual tone signal. The pedal tone signal thus obtained is passed through a frequency shifter to become a slightly frequency-deviated signal whose frequency is not an exact integral submultiple of the frequency of the manual tone signal. In this instrument, concurrent sounding of the pedal tone and the manual tone brings out a beat as in an instrument having tone generators of an individual oscillating system.

Description

United States Patent [191 Suzuki July 30, 1974 [5 ELECTRONIC MUSICAL INSTRUMENT 2,892,372 6/1959 Bauer 84/1.25 WITH FREQUENCY DEVIATED PEDAL 3,098,888 7/1963 Tomcik 84/1.17 TONE SIGNAL 3,488,515 1/1970 Hiyoshl 84/101 X 3,535,969 10/1970 Bunger 84/D1G. ll [75] lnventor: Akihisa Suzuki, Kamimura, Japan 3,598,892 8/1971 Yamashita 84/].01 3,619,469 111971 Ad h' 84 1.17 [73] Assignee: Nippon Gakki Seizo Kabushiki M l Kaisha, Shizuoka-ken, Japan 22 F1 d: O t. 17, 1972 Primary Examiner-Richard B. Wilkinson 1 c Assistant Examiner-Stanley J. Witkowski 1 1 pp 298,357 Attorney, Agent, or Firm-Holman & Stern Related US. Application Data [63] Continuation-impart of Ser. No. 113,249, Feb. 8,

1971, abandoned. 57 ABSTRACT [30] Foreign Application Priority Data In an electronic musical instrument, a tone signal for Feb. 10, 1970 Japan 45-12784 the pedal keyboard is obtained by frequency-dividing Feb. 26, 1970 Japan 45-19153 the ma ual tone signal, The pedal tone signal thus 0btained is passed through a frequency shifter to become [52] US. Cl. 84/117, 84/124 3 lightly frequency-deviated signal whose frequency is [51] Int. Cl. GlOh l/04 t an exa t integral ubmultiple of the frequency of Field 01 Search 122-125, the manual tone signal. In this instrument, concurrent DIG. 1 1, 25 sounding of the pedal tone and the manual tone brings out a beat as in an instrument having tone generators [56] efe enc Cited of an individual oscillating system.

UNITED STATES PATENTS 2,879,683 3/1959 Martin 84/124 4 Claims, 10 Drawing Figures PHASE SHIFTER MODULATOR 0 PS 1 M1 l fa f f0 --Af c LATOR S b FILTER *1 I Af d \ EXTRENELY LOW FREQUENCY f0 0 OSCILLATOR PATENTEU 3.826.859

SHEET 1 0f 3 PHASE SHIFTER MODULATOR PS MI I f0 1 fc-Af s I C MODULATOR FILTER Af d.

EXTREMELY LOW FREQUENCY f Af LFO OSCILLATOR UK UKT LOwER KEYBOARD "LONE-COLORING CIRCUIT AMPLIFIER s LK 'LKT A SOUND LOWER KEYBOARD PEDAL TONE- SOURCE SWITCHING CIRCUIT COLORING CIRCUIT SP CIRCUIT PM D PK PKT FS IEIIBIR BEAR ERA-m BARKER- CIRCUIT CIRCUIT CIRCUIT DIvIOE F I G. 3

' UPPER KEYBOARD TO E-COLORING CIRCUIT UK UKT UPPER KEYBOARD LOWER KEYBOARD SWITCHING CIRCUIT TONBCOLORING C'RCUIT AMPLIFIER I S IL IILK |L LK-H A LOWER KEYBOARD gaggg; SWITCHING CIRCUIT EE L SP PRIORITY FREQUENCY IFREQUENCY E|E; %Al|J lTTONE-COLORING MEMORY -DIvIsION CIRCUIT C|RCU|T QYg QN PATENTEU JUL30I974 UPPER KEYBOARD SWITCHING CIRCUIT sum 2 or 3 UPPER KEYBOARD TONE -COLOR|NG CIRCUIT UK UKT LOWER KEYBOARD LOWER KEYBOARD TONE-COLORING AMPLIFIER SWITCHING CIRCUIT /CIRCU|T s L K T L KT A SOUND SOURCE ERIQS PEDAL SWFTCHING SP CIRCUIT CIRCUIT /C|RCU|T PM D PK FS EEEEW FREQUENCY CIRCUIT DEVIATION DIVICE F l G. 5

PHASE SHIFTER MODULATOR U PS Ml FILTER 9 h OUT 8 b C F MODULATOR M2 d fl L F O T EXTREMELY LOW FREQUENCY OSCILLATOR PIIIENIEIIIIIIB 3826.859

SHEET 3 BF 3 F I G. 6

UPPER KEYBOARD UFBPER KEYBOARD SWITCHING CIRCUIT [TONE-COLORING CIRCUIT U K U K T LOWER KEYBOARD LOWER KEYBOARD 0| QR SWITCHING CIRCUIT 5%,? AM/PUF'ER S L K I L K T A SOUND FREQUENCY- SOURCE DIVISION FREQUENCY- 5P CIRCUIT C|RCU|T /DEVIAT|ON DIVICE PM D FS P K K I-2 \PEDAL SWITCHING CIRCUIT F l G. 7 LflO 0 8. E 1? CC C OONTROL VOLTAGE F l G. 9

6 CC# C 2 O E CONTROLLING \L 1 l 1 L VOLTAGE our ELECTRONIC MUSICAL INSTRUMENT WITH FREQUENCY-DEVIATED PEDAL TONE SIGNAL This is a continuation-in-part of application Ser. No. 113,249, filed on Feb. 8, 1971, which is now abandoned.

BACKGROUND OF THE INVENTION Heretofore, in electronic musical instruments, there has been an independent pedal tone generator system which is provided with tone generators especially for pedal tones other than manual tones; and in a second alternative system a frequency division tone generator system is provided with tone generators in common for manual tones and pedal tones wherein a desired signal is selected and memorized and then is frequencydivided down to a pedal tone.

In the former system, the pedal tone signals are produced by their own tone generators separated from those for the manual tones. Therefore, when the manual tone and the pedal tone are sounded at the same time, a slight difference of the frequencies between these tone signals produces a natural beat sound, whereby a musical performance can be attained in such a way that the manual tone comes out prominently, and the pedal tone is increased in tone heaviness (richness as a base tone). Therefore, the former system is very effective in tone quality, but has a drawback in that it is hard to stabilize an oscillating frequency at such a low frequency region as an individual tone signal oscillator.

On the other hand, the latter system which is utilized for most of electronic organs has advantages in that it is stable in frequency and low in production cost, but however has disadvantages that the beat sound such as can be found in the individual tone generator system cannot be obtained, because the manual tone and the pedal tone are always in relationship of an exact harmonic.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide a novel organization of an electronic musical instrument in which a natural beat sound is produced between a manual tone and a pedal tone, whereby all of the above described drawbacks of the conventional devices can be eliminated.

Another object of the present invention is to provide an electronic musical instrument of a frequencydivision tone generator system, in which, when a pedal tone and a manual tone are produced at the same time, a beat sound effect which is rich in natural sound sensation as is found in an electronic musical instrument having an individual tone. generator system, can be obtained.

A further object of the present invention is to provide an electronic musical instrument of a frequencydivision tone generator system, in which a frequency shifter adapted to slightly deviate a pedal tone frequency is provided in a pedal sound system and a voltage control type oscillator in the frequency shifter is controlled by a voltage furnished from a memorizing selector circuit whereby the frequency deviation is controlled in response to a tone pitch of the pedal tone.

A still further object of the present invention is to provide a novel electronic musical instrument which can operate in a purely electronic manner and is simple in construction and economical in production.

The foregoing objects and other objects as well as the characteristic features of the invention will become more apparent from the following detailed description and the appended claims when read in conjunction with the accompanying drawings, in which like parts are designated by like reference symbols.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawings:

FIG. 1 is a block diagram showing an example of the frequency shifter employed in a pedal tone generating circuitry of an electronic musical instrument, according to the present invention;

FIG. 2 is a block diagram illustrating one embodiment of the electronic musical instrument of the present invention;

FIG. 3 is a block diagram showing another embodiment of the electronic musical instrument according to the present invention;

FIG. 4 is a block diagram showing a further embodiment of the electronic musical instrument according to the present invention;

FIG. 5 is a block diagram illustraing an example of the frequency shifter used in the electronic musical instrument shown in FIG. 4;

FIG. 6 is a block diagram showing a still further embodiment of the electronic musical instrument according to the present invention;

FIG. 7 is a graphic diagram showing a characteristic of a control voltage derived from a memorizing selector with respect to note names;

FIG. 7a illustrates by way of example a circuit for producing an output as shown in FIG. 7;

FIG. 8 is a graphic diagram illustrating a characteristic of control voltage VS. oscillation frequency of an extremely low frequency oscillator used in the frequency shifter shown in FIG. 5; and

FIG. 9 is a graphic diagram showing a pedal tone frequency characteristic with respect to note names.

DETAILED DESCRIPTION OF THE INVENTION With reference now to the accompanying drawings and more particularly to FIGS. 2 and 3, embodiments of the electronic organ according to the present invention are illustrated in the form of a block diagram. In these figures, the arrangement of parts other than a frequency shifter FS shows one arrangement of a conventional electronic organ having a frequency-division tone generator system. The embodiment according to the present invention comprises a sound source circuit S (including tone generators), an upper keyboard switching circuit UK, an upper keyboard tone-coloring circuit UKT, a lower keyboard switching circuit LK, a lower keyboard tone-coloring circuit LKT, a memorizing selector circuit PM which serves to select, in association with the pedal key depression, one tone signal from the sound source circuit S and memorizingly connect it to the succeeding circuit until another pedal is next depressed (this can be constructed mechanically by a lock-and-release type push button switch or electrically by a circuit described in the US. Pat. No.

3,488,515 to Hiyoshi), a frequency-division circuit D which serves to frequency-divide a selected tone signal from the memorizing selector circuit PM down to a desired frequency, a pedal switching circuit PK, a pedal tone-coloring circuit PKT, the frequency shifter FS which is adapted to shift (deviate) the frequency of the pedal tone signal by as much as a frequency which is sufficiently lower than that of the pedal tone signal, an amplifier A, and a loudspeaker SP.

Now, if parts other than the frequency shifter F8 are taken into consideration, the combination of the parts is completely similar to that of the conventional electronic organ having the frequency-division tone generator system, and musical tone signals from the sound sources are properly tone-colored by the upper keyboard tone-coloring circuit UKT and the lower keyboard tone-coloring circuit LKT after having passed through the upper keyboard switching circuit UK and the lower keyboard switching circuit LK, respectively. Then, the thus tone-colored signal is amplified in the amplifier A and converted into a sound through the loudspeaker SP. In a parallel circuit, after a musical tone signal through the memorizing selector circuit PM has been frequency-divided by the frequency-divider D, it is keyed by the pedal switching circuit PK, properly tone-colored through the pedal tone-coloring circuit PKT, and in the absence of a frequency deviation device then, the thus tone-colored signal is amplified by the amplifier A and further converted into a sound by the loudspeaker SP. In this case (without a frequency shifter), if both the pedal switching circuit PK and the upper keyboard switching circuit UK or the lower keyboard switching circuit LK are rendered conductive at the same time, both a pedal sound and an upper keyboard sound or a lower keyboard sound are simultaneously produced. Since these two sounds are originated from the same musical tone signal, they are the same in tone-pitch or are in the relationship of exact harmonics, as a result of which only a coupler effect is obtained at best, but a beat sound as obtainable in the case of an individual tone generator system cannot be obtained, and accordingly it is inevitable for the obtained sound to be rather monotonous.

In order to overcome the above drawbacks, such an arrangement is made in the present invention that a natural beat sound is obtained between the pedal sound and the upper or lower keyboard sound by slightly deviating the frequency of the pedal sound. A device by which the frequency of the musical tone signal is thus slightly deviated, is represented by reference symbol F in FIGS. 2 and 3, and the device FS is illustrated in greater detail in the form of a block diagram in FIG. 1.

Now, with reference to FIG. 1, a musical tone signal from a musical sound source S (the signal generally comprises a plural frequency components and moreover it varies from time to time in accordance with the progression of the musical performance, but, for the convenience of explanation in this specification, the signal is represented by a single frequency of f,,Hz) is converted by a phase-difference network PS into two musical tone signals which are 90 phase shifted in phase from each other. Further, two signals (as carrier waves) furnished from an extremely low frequency oscillator LFO and having a frequency Af sufficiently lower than that of the musical tone signal and shifted by 90 in phase from each other are respectively amplirude-modulated with the above mentioned phasedifferent tone signals (as modulating waves) in modulators M and M Then the modulated output signals from the modulators M. and M are mixed together and an unnecessary extremely low frequency signal component is eliminated by a high-pass filter F thereby to obtain a signal having a frequency f,, :L Af, and further only a signal having a frequency f,, Af is finally taken out.

The above processes can be shown by the following formulas:

Signal at a terminal a a cos w t (w 21rf,,),

Signal at a terminal I) a sin w t (w 2'n-f,,)

Signal at a terminal c A cos pt 2 ZrrAf) Signal at a terminal d A sin pt (p 21rAf) where a and A represent the signal amplitudes, respectively.

The signal at the terminal a and c leads the signal at the terminal b and d by 90 in phase, respectively, accordingly;

M output: A(l m cos wt) cos pt M output: A(l m sin wt) sin pt where m a/A (modulation factor). Therefore, a mixed signal will be:

M +M =2 VTA cos (pt-1r/4)+mA cos (wp)t.

Accordingly, when Af component is eliminated by means of the filter, the resultant output will be mA cos (0) p)t, and a signal having a frequency f,, Af that is lower by as much as a frequency Af than the frequency f,, of the musical sound signal, can be obtained.

As a result, a pedal tone signal lower by as much as Af than an original pedal tone signal is obtained by inserting such a frequency shifter in a pedal tone generating circuitry, whereby a beat sound whose frequency is Af can be obtained by simultaneously producing a pedal sound and a manual sound.

In the embodiment shown in FIG. 2, the higher harmonies of the pedal sound are also deviated in frequency by as much as Af. If this deviated quantity is represented by a ratio of frequency deviation, for instance in percent, the ratio becomes rather small for higher harmonics, and therefore a beat effect cannot be very pronounced as far as higher harmonics are concerned.

In order to obviate this disadvantage another circuit shown in FIG. 3 is provided,.in which the frequency shifter FS is provided immediately before the pedal switching circuit. In this circuit, only a fundamental component is taken out from the memorizing selector circuit PM and is fed to the frequency shifter FS, thereby to be deviated in frequency by as much as Af, and then the waveform of the fundamental frequency signal is converted by the tone-coloring circuit PKT into a more complicated waveform, thereby to obtain desired higher harmonics. In this case, both the fundamental and higher harmonics of the pedal tone are deviated in frequency to the same extent in terms of percent, and when the manual keyboard sound and the pedal sound are simultaneously produced, the same beat effect as in the individual tone generator system can be obtained.

FIG. 4 illustrates a further embodiment of the present invention, in which a frequency shifter FS serves to deviate its input signal frequency f}, into its output signal frequency f,, A f (where Af is an extremely low frequency of 0.5 Hz to 10 Hz), and the extremely low frequency is varied by a controlling voltage furnished from a memorizing selector circuit PM. i

FIG. 5 shows an embodiment of the frequency shifter FS shown in FIG. 4. The circuit of this embodiment comprises a phase-difference network PS wherein a musical tone signal is supplied to its input and two musical sound signals differing by 90 in phase within a frequency range for use are produced at the output, a voltage control type variable extremelylow frequency oscillator LFO adapted to generate two signals having a frequency (0.5 Hz) which is extremely lower than that of a musical tone signal and which are different by 90 in phase from each other, amplitude-modulators M and M which serve to amplitude-modulate the extremely low frequency signals (as carrier waves) furnished through terminals 0 and d with the musical sound signals (as modulating waves) passing through terminals a and b respectively, and a high-pass filter F adapted to cut off an oscillating frequency component furnished from the extremely low frequency oscillator LFO.

Now, assuming that the phase of the musical tone signal at the output terminal b of the phase-difference network PS lags by 90 behind that at the output terminal a and the phase of a signal (carrier wave) to be modulated at the output terminal d lags by 90 behind that at the output terminal c, each of the signals at the terminals a, b, c and d is represented by the following formulas respectively:

Therefore, when the signal at the terminal c is amplitude-modulated with the musical sound signal at the terminal a in the amplitude-modulator M an output of the amplitude modulator M, is represented by a formula below:

M output A cos pt (I m cos out) A cos pt (mA/2) cos (w +p)t (mA/2) cos (m p)t, where m Ka means the amplitude modulation factor (K is the modulation sensitivity).

In the same way as described above, when the signal at the terminal d is amplitude-modulated with the musical sound signal at the terminal in the amplitudemodulator M an output of the amplitude-modulator M is represented by a formula below:

M output A sin pt (I m sin wt) A sin pt (mA/2) cos (w +p)t (mA/2) cos ((0 -p)t where m Ka means the amplitude modulation factor (K is the modulation sensitivity). Then, those outputs from the amplitude modulators M and M are combined at a terminal g into a signal shown by the following formula:

Signal at the terminal g A (cos pt sin pt) mA cos (w p)t Successively, Af component is removed from this signal by means of the filter F, and as a result a signal represented by the formula; mA cos (w p)! is obtained at the output terminal h of the filter F. The angular frequency of this signal is lower by as much as p(Af in frequency) than that of the original musical tone signal at a terminal (1,. In this case, the extremely low frequency oscillating circuit LFO is one whose frequency is varied by a control voltage applied thereto.

The relationship between a controlling voltage applied to a frequency control terminal T of the extremely low frequency variable frequency oscillator LPG and an oscillating frequency thereof is, for instance, as shown in FIG. 8 and the oscillating frequency becomes higher with increasing controlling voltage. Therefore, when a voltage shown in FIG. 7 is produced in the memorizing selector circuit PM by an additional circuit therein (as exemplarily illustrated in FIG. 7a) and the thus produced voltage is fed to the control ter minal T of the variable frequency oscillator LFO, a frequency deviation can be obtained in response to a tonepitch (note name) of the pedal sound and further the characteristic of the pedal sound frequency can be made, for instance, as shown in FIG. 9 to respond to each of tone-pitches (note names).

In embodiments described above, although the frequency of the higher harmonics is also deviated by as much as -Af, the deviated quantities are smaller in ratio as compared with the fundamental when represented in percent (ratio of frequency deviation) and therefore would not be undesirable in an actual use.

FIG. 6 illustrates a still further embodiment of the present invention. FIG. 6 is different from FIG. 4 in that the frequency deviation circuit FS is arranged between the frequency-division circuit D and the pedal switching circuit and tone-coloring circuit DK. Although the operation of this embodiment is substantially the same as that of FIG. 4, only the fundamental component of the output signal of the memorizing selector circuit PM is frequency-deviated by as much as Af in the frequency deviator device FS and then, desired higher harmonics are obtained in the pedal tone keyer and tone-coloring circuit PK. As a result, the operation of this embodiment is different from that of FIG. 4 in that both the fundamental wave component and the higher harmonic wave components are deviated by the same percentage value.

While a few embodiments of the present invention have been illustrated and described in detail, it is particularly understood that the present invention is not limited thereto or thereby.

I claim:

1. An electronic musical instrument producing an accoustic beat effect by generating a frequency deviated pedal tone signal, comprising:

a musical sound signal source for generating tone signals for manual tones and pedal tones in a frequency division tone generator system;

a switching circuit for a manual keyboard having manual keys and connected to said musical sound signal source for switching tone signals therefrom;

a manual keyboard tone-coloring circuit connected to said manual keyboard switching circuit for tonecoloring the switched tone signals and providing a first output signal representative thereof;

memorizing selector means operated by a set of pedal keys and connected to said musical sound signal source for selecting a tone signal from said source upon depression of one of said pedal keys, and memorizing said selected tone signal until another of said pedal keys is depressed;

frequency dividing means connected to said memorizing selector means for frequency-dividing said selected tone signal and providing an output frequency therefrom;

a pedal switching circuit operated by said pedal keys and connected to said frequency dividing means for switching said output frequency from said frequency dividing means;

a pedal tone-coloring circuit connected to said pedal switching circuit for tone-coloring said output frequency switched thereform and providing a second output signal representative thereof;

means defining an interconnecting point connecting said first output signal from said manual keyboard tone-coloring circuit with said second output signal from said pedal tone-coloring circuit;

and frequency deviation means connected in series between said frequency dividing means and said interconnecting point for reducing said output frequency of said frequency dividing means by a constant predetermined frequency so that when said first and second output signals are combined at said interconnecting point a combined signal is produced having an acoustic beat effect.

2. An electronic musical instrument as claimed in claim 1, wherein said frequency deviation means includes a low frequency oscillator, and wherein said memorizing selector means includes means furnishing a controlling voltage connected to alter an output frequency of said low frequency oscillator.

3. An electronic musical instrument as claimed in claim 1 wherein said frequency deviation means is connected in series between said frequency dividing means and said pedal switching circuit.

4. An electronic musical instrument as claimed in claim 1 wherein said frequency deviation means is connected in series between said pedal tone-coloring circuit and said interconnecting point.

Claims (4)

1. An electronic musical instrument producing an accoustic beat effect by generating a frequency deviated pedal tone signal, comprising: a musical sound signal source for generating tone signals for manual tones and pedal tones in a frequency division tone generator system; a switching circuit for a manual keyboard having manual keys and connected to said musical sound signal source for switching tone signals therefrom; a manual keyboard tone-coloring circuit connected to said manual keyboard switching circuit for tone-coloring the switched tone signals and providing a first output signal representative thereof; memorizing selector means operated by a set of pedal keys and connected to said musical sound signal source for selecting a tone signal from said source upon depression of one of said pedal keys, and memorizing said selected tone signal until another of said pedal keys is depressed; frequency dividing means connected to said memorizing selector means for frequency-dividing said selected tone signal and providing an output frequency therefrom; a pedal switching circuit operated by said pedal keys and connected to said frequency dividing means for switching said output frequency from said frequency dividing means; a pedal tone-coloring circuit connected to said pedal switching circuit for tone-coloring said output frequency switched thereform and providing a second output signal representative thereof; means defining an interconnecting point connecting said first output signal from said manual keyboard tone-coloring circuit with said second output signal from said pedal tone-coloring circuit; and frequency deviation means connected in series between said frequency dividing means and said interconnecting point for reducing said output frequency of said frequency dividing means by a constant predetermined frequency so that when said first and second output signals are combined at said interconnecting point a combined signal is produced having an acoustic beat effect.

2. An electronic musical instrument as claimed in claim 1, wherein said frequency deviation means includes a low frequency oscillator, and wherein said memorizing selector means includes means furnishing a controlling voltage connected to alter an output frequency of said low frequency oscillator.

3. An electronic musical instrument as claimed in claim 1 wherein said frequency deviation means is connected in series between said frequency dividing means and said pedal switching circuit.

4. An electronic musical instrument as claimed in claim 1 wherein said frequency deviation means is connected in series between said pedal tone-coloring circuit and said interconnecting point.

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