Title:
ELECTRONIC MUSICAL INSTRUMENT HAVING TONE START PROMINENCE CIRCUIT
United States Patent 3762265
Abstract:
An electronic musical instrument having a conventional music playing circuit arrangement with a tone signal passage including tone generators, tone keyers, tone coloring filters, an amplifier and a loudspeaker is further provided with a tone start prominence circuit arrangement. The arrangement comprises an amplitude modulator inserted in the tone signal passage, a detector connected to the tone signal passage for detecting the start of the tone signal being played, and a waveform shaper producing a percussive waveform signal upon receipt of the detected signal and controlling the modulator so that the start of the tone signal be percussively emphasized. As an improved embodiment, a tone color modulator is further inserted in the tone signal passage and is controlled by the above-mentioned detected signal, thereby emphasizing the start of the tone signal more clearly.
US Patent References:
MANUAL OR KNEE OPERABLE EFFECT SELECTOR SYSTEM IN ELECTRONIC MUSICAL INSTRUMENT
Hashino - March 1970 - 3499094
METHOD AND SYSTEM FOR GENERATING TREMOLO EFFECTS IN ELECTRONIC MUSICAL INSTRUMENTS
Adachi - September 1971 - 3603714
Apparatus for producing pedal sounds in electric musical instruments
Mabuchi - June 1965 - 3189674
Keyboard electric musical instrument
Volodin - November 1966 - 3288909
ELECTRONIC MUSICAL APPARATUS IMPROVED IN A MUSICAL TONE GENERATING CIRCUIT
Kameoka et al. - October 1970 - 3532799
MANUAL OR KNEE OPERABLE EFFECT SELECTOR SYSTEM IN ELECTRONIC MUSICAL INSTRUMENT
Hashino - March 1970 - 3499094
METHOD AND SYSTEM FOR GENERATING TREMOLO EFFECTS IN ELECTRONIC MUSICAL INSTRUMENTS
Adachi - September 1971 - 3603714
Apparatus for producing pedal sounds in electric musical instruments
Mabuchi - June 1965 - 3189674
Keyboard electric musical instrument
Volodin - November 1966 - 3288909
ELECTRONIC MUSICAL APPARATUS IMPROVED IN A MUSICAL TONE GENERATING CIRCUIT
Kameoka et al. - October 1970 - 3532799
Application Number:
05/212014
Publication Date:
10/02/1973
Filing Date:
12/27/1971
View Patent Images:
Export Citation:
Assignee:
Nippon Gakki Seizo Kabushiki Kaisha (Hamamatsu-shi, Shizuoka-ken, JA)
Primary Class:
Other Classes:
984/310, 984/324, 984/377, 84/699
International Classes:
G10H1/04; G10H1/06; G10H5/00; G10H1/02
Field of Search:
84/1.01,1.19,1.21,1.23,1.24,1.25,1.26
Primary Examiner:
Wilkinson, Richard B.
Assistant Examiner:
Weldon U.
Claims:
I claim
1. An electronic musical instrument comprising a music playing circuit arrangement having a tone signal passage through which a tone signal is conducted when the instrument is played, said tone signal passage being defined by and including serially interconnected tone generators, tone keyers, tone coloring filters, an amplifier, and a loudspeaker, said instrument further including an amplitude modulator means disposed between said tone coloring filters and amplifier for amplitude modulating a tone signal being played in accordance with a control signal, a detector means coupled to said tone signal passage between said keyers and said tone coloring filters for detecting said tone signal being played and for generating a detected signal representative of the envelope of said tone signal being played, and a wave form shaper means connected to said detector means for producing at an output thereof a percussive wave form control signal at the commencement of the leading edge of said detected signal, the output of said wave form shaper means being connected to said amplitude modulator means and defining the control signal therefor, whereby the level of the tone signal being played is enhanced according to said percussive wave form signal, and wherein the tone signal passage further includes a tone color modulator means connected to said amplitude modulator for modulating the tone color of the tone signal being played in accordance with a control signal, said output of said wave form shaper means being connected to said tone modulator means and defining the control signal therefor, whereby the harmonic components of the tone signal being played are also enhanced according to said percussive wave form signal.
2. An electronic musical instrument as set forth in claim 1, wherein said wave form shaper means includes a differentiating circuit and a biasing resistor connected to said differentiating circuit, whereby a wave form having a sharp rising leading edge and a slowly decaying trailing edge is thereby obtained.
1. An electronic musical instrument comprising a music playing circuit arrangement having a tone signal passage through which a tone signal is conducted when the instrument is played, said tone signal passage being defined by and including serially interconnected tone generators, tone keyers, tone coloring filters, an amplifier, and a loudspeaker, said instrument further including an amplitude modulator means disposed between said tone coloring filters and amplifier for amplitude modulating a tone signal being played in accordance with a control signal, a detector means coupled to said tone signal passage between said keyers and said tone coloring filters for detecting said tone signal being played and for generating a detected signal representative of the envelope of said tone signal being played, and a wave form shaper means connected to said detector means for producing at an output thereof a percussive wave form control signal at the commencement of the leading edge of said detected signal, the output of said wave form shaper means being connected to said amplitude modulator means and defining the control signal therefor, whereby the level of the tone signal being played is enhanced according to said percussive wave form signal, and wherein the tone signal passage further includes a tone color modulator means connected to said amplitude modulator for modulating the tone color of the tone signal being played in accordance with a control signal, said output of said wave form shaper means being connected to said tone modulator means and defining the control signal therefor, whereby the harmonic components of the tone signal being played are also enhanced according to said percussive wave form signal.
2. An electronic musical instrument as set forth in claim 1, wherein said wave form shaper means includes a differentiating circuit and a biasing resistor connected to said differentiating circuit, whereby a wave form having a sharp rising leading edge and a slowly decaying trailing edge is thereby obtained.
Description:
BACKGROUND OF THE INVENTION
This invention relates to an electronic musical instrument wherein the start of the tone signal is emphasized prominently.
An electronic musical instrument having an upper keyboard, a lower keyboard, and a pedal keyboard is ordinarily played in such a manner that the upper keyboard assumes the melody part, the lower keyboard assumes the accompaniment part, and the pedal keyboard is used to play the bass part. However, in some cases, the melody part is played on the lower keyboard and the accompaniment part is played on the upper keyboard. Moreover, even in the ordinary case where the accompaniment is played on the lower keyboard, various modes of rendition, such as varying chords slowly for hamonization, intermitting chords quickly for rhythmic accompaniment, or playing a counter melody together with the rhythmic chords, are possible.
In all of the above described cases, the balance in volume between the melody part and the accompaniment part is not always constant, and a "manual balancer" knob must be operated during the rendition (playing) of the electronic musical instrument so that a desired tone balance is obtained between the melody part and the accompaniment part, such a procedure posing a difficulty in the playing of the musical instrument.
The above described difficulty can be obviated, if the volume of the sound (tone signal) be elevated remarkably at the initial instant or very start of the sound duration to exhibit a prominent attack. Furthermore, it is found that the sound of a string instrument of a type plucked by fingers or the like can be simulated by an electronic musical instrument wherein the tone level and tone color (especially harmonic components) of the sound be exaggerated at the initial instant of the sound creation.
SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to provide an electronic musical instrument wherein the tone signal is given a prominent attack at the very start portion of the tone signal existence.
Another object of the invention is to provide an electronic musical instrument whereby the necessity of the manipulation of the manual balancer knob during the performance of the musical instrument can be substantially eliminated even in the cases where the intensity of the accompaniment is to be varied widely depending on the playing manner.
Still another object of the invention is to provide an electronic musical instrument whereby the sound of the stringed musical instruments of a type plucked by fingers or the like can be simulated more effectively.
These and other objects of the present invention can be achieved by an electronic musical instrument comprising a music playing circuit arrangement having a tone signal passage, an amplitude modulator inserted in the tone signal passage, a detector connected to the tone signal passage for detecting the start of the tone signal being played, and a waveform shaper producing a percussive waveform signal upon receipt of the detected signal and controlling the modulator so that the start of the tone signal be percussively emphasized.
In another aspect thereof, the invention is directed to toward an electronic musical instrument comprising a music playing circuit arrangement having a tone signal passage, an amplitude modulator and a tone color modulator inserted in the tone signal passage, detector connected to the tone signal passage for detecting the start of the tone signal being played, and a waveform shaper producing a percussive waveform signal upon receipt of the detected signal and controlling the modulators in a way that the tone level is shortly enhanced and the tone color is shortly rendered rich in higher harmonics at the very start of the tone signal.
The nature, principle, and the utility of the present invention can be more clearly understood from the following detailed description of the invention when read in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals and characters.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a block diagram showing a circuit outline of an electronic musical instrument constituting a preferred embodiment of the present invention:
FIG. 2 is a detailed circuit diagram of the important part of the electronic musical instrument shown in FIG. 1;
FIG. 3 is an explanatory diagram of the envelope of the signal level variation in the embodiment shown in FIGS. 1 and 2;
FIG. 4 is a block diagram showing a circuit outline of another example of the electronic musical instrument constituting a second embodiment of the present invention; and
FIG. 5 is a detailed circuit diagram of the important part of the electronic musical instrument shown in FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is indicated an electronic musical instrument comprising tone generators 1 generating tone signals corresponding to desired notes, tone keyers 2 which are individually open or closed in accordance with the manipulation of the keys in, for instance, a lower keyboard K for permitting the tone signals from the tone generators to pass through the tone keyers 2, tone-color filters 3 for imparting tone-colors to the tone signals, an amplitude modulator 4 which varies the amplitude of the output signal delivered from the tone-color filters 3 responsive to a separately formed control signal, and an amplifier 5 which amplifies the output signal from the amplitude modulator 4 and delivers the output to a loudspeaker SP. These elements, 1, 2, K, 3, 4, 5, 6 and SP constitute a conventional music playing circuit arrangement having a tone signal passage. The electronic musical instrument also comprises a rectifying or detector circuit 6 which rectifies or detects the output signal from the tone keyers 2 for generating a square wave signal representing the envelope thereof, and a waveform shaper 7 which differentiates the output from the circuit 6 for forming a percussive pulse signal with an abrupt build-up and a subsequent gradual decay constituting the above mentioned separately formed gate signal.
In FIG. 2, there is illustrated in more detail the relation between the detector circuit 6, waveform shaper circuit 7, and the amplitude modulator 4 shown in FIG. 1, wherein the detector circuit 6 further includes an amplifier portion 6a.
The operation of this embodiment of the invention will be described with reference to FIGS. 1 and 2.
The tone generators 1 are constantly generating tone signals of the desired notes constituting octaves of musical scale, and these signals are selectively passed through the tone keyers 2 in accordance with the performance on the keyboard K. Each of the signals thus selected is imparted with a desired tone-color in the tone-color filters 3, and the amplitude of the output signal is controlled in the amplitude modulator 4 depending on the control signal, the amplitude being at a normal level when no control signal is supplied from the wave shpaer 7 and being enhanced to a prominent level when a control signal of the percussive waveform is supplied from the wave shaper 7. The output of the amplitude modulator 4 is amplified in the amplifier circuit 5 and converted into an audible sound through the loudspeaker SP.
If the keyboard K is operated in a staccato manner, the tone signals passed through the tone keyers 2 will be of a nature having sharply rising leading edges and frequent interruptions forming spaced-apart individual soundings with separate starts. Such signals are applied to the input terminal IN in the circuit diagram shown in FIG. 2, and one part thereof is passed through the tone-color filter 3 to the amplitude modulator 4, while the other part thereof is supplied to the amplifier portion 6a of the detector circuit 6. The amplifier portion 6a includes transistors Q1 and Q2 and amplifies the part of the signals to be supplied to the detector circuit 6 thereafter. The detector circuit 6 includes a transistor Q3 which acts as a class B amplifier only picking up the positive portions of the tone signals. The positive portions of the signals are thereafter supplied to the waveform shaper circuit 7. The waveform shaper circuit 7 includes a transistor Q4 provided with a differentiation circuit having a capacitor C1 and a resistor R2 and a by-passing resistor R1 at the output side thereof. As a result, when the sharply rising staccato renditioned signals arrive at the waveform shaper circuit 7, the sharply rising leading edge of every signal sounding is differentiated by the differentiation circuit, and a triangular pulse thus obtained is superposed onto a voltage obtained through the by-passing resistor, as indicated in FIG. 3.
When a control signal thus obtained is supplied to the gate of a field-effect transistor FET included in the amplitude modulator 4, the effective resistance of the field-effect transistor FET is varied in accordance with the control signal, and the extent of modulation in the amplitude modulation transistors Q5 and Q6 is also varied in accordance with the control signal.
Thus, when the output signal from the tone keyers 2 is supplied to the amplitude modulator 4 after it has passed through the tone-color filters 3, the signal is amplitude-modulated under the control of the control signal supplied to the gate of the field-effect transistor FET, and is further amplified in a transistor Q7. The output signal from the amplitude modulator 4 inclusive of the transistor Q7 is delivered from the output terminal OUT and sent through the amplifier circuit 5 to the loudspeaker SP. From the loudspeaker SP, a crisp and staccato sound can be obtained because of the above described organization of the circuitry. The level of the initially rising-up portion of the output tone is preferably set at a value 3 to 6 dB higher than the rest of the sustaining part of the tone signal.
In the case where the keyboard K is operated in a legato manner, no initial rising portion every tone start exists in the output tone signal from the tone keyers 2 except that obtained at the time of the first key is depressed initially, whereby the output signal from the waveform shaper circuit 7 will be made constant all the rest of time, and the resultant sound from the loudspeaker SP will not be imparted with the above described enhancing effect.
For this reason, when it is desired that the melody part of music be played on the lower keyboard on which the accompaniment part has been so far played, a mere rendition in a staccato manner will sufficiently elevate the apparent sound level of the melody part now played on the lower keyboard, and the conventional manipulation of the manual balancer knob during the performance will be unnecessary.
The above described circuitry of the electronic musical instrument according to the present invention, with slight modification, may also be utilized for simulating the sound of certain kinds of stringed instruments.
When the sound of a string instrument such as a guitar, having strings plucked by fingers or the like, is analyzed, it turned out that the envelope of the sound rises sharply at its initial portion of the period and then decays in a non-linear manner, and that the content of the higher harmonics decays far faster than the fundamental.
Such features of the sound of the string instrument can be obtained in the circuit of an electronic musical instrument as shown in FIGS. 4 and 5, which constitutes another embodiment of the present invention.
Referring to FIG. 4, there is indicated the circuit of an electronic musical instrument comprising tone geenerators 1 for generating desired notes, tone keyers 2 for selectively passing some of the notes to the subsequent stage under the control of the keyboard K, a tone-color filters 3, an amplitude modulator 4 which modulates in amplitude the output signal form the tone-color filters 3 depending on a signal separately formed in response to the operation of the keyboard K, an amplifier circuit 5 and a loudspeaker SP, a detector circuit 6, and a waveform shaper circuit 7, all being organized and connected in the similar manner as in the first embodiment of the invention except that a minor change is made in the circuit 7, and a tone-color modulator 8 is further provided between the amplitude modulator 4 and the amplifier.
Referring to FIG. 5, there is illustrated in more detail the relation between the detector circuit 6, waveform shaper circuit 7, and the amplitude modulator 4 shown in FIG. 4, wherein the detector circuit 6 includes an amplifier portion 6a. It will be apparent in the figures that, in this example, a resistor R1 by-passing a capacitor C1 in the circuit 7 is omitted, and another capacitor C2 is provided in parallel with a biasing resistor R2, so that the steady portion in the control signal is thereby eliminated and the inpulsive portion thereof is exaggerated. Furthermore, in the circuit of the second example, a tone-color modulation circuit 8 is provided between the amplitude modulator 4 and the amplifier circuit 5 as described above and is connected in such a manner that the output signal from the amplitude modulator 4 is supplied to the input side of the tone-color modulator 8, and the higher harmonic components among the signal thus supplied are emphasized shortly upon receipt of the control signal obtained from the waveform shaper circuit 7, and come back to the normal non-emphasized state.
With the above described organization of the circuit of this example since all of the circuit members from 1 through 6 are equal to the circuit members of the corresponding reference numerals in the first example, the operation of this part of the circuit is quite similar to that described hereinbefore.
Thus, when the keyboard K is operated in a staccato manner, the sound signals passed through the tone keyers 2 are supplied at the input terminal IN of FIG. 5, and one part thereof is passed through the tone-color filters 3 to the amplitude modulator 4, and the other part of the sound signals is passed to the detector circuit 6. In the detector circuit which acts as a class B amplifier, only the positive parts of the signals are picked up and supplied to the waveform shaper circuit 7.
In the waveform shaper circuit 7, the sharp leading edge of each of the signals is differentiated by the differentiation circuit, and a triangular pulse having a sharply rising leading edge is obtained. This signal is applied as a control signal to the gate terminal of a field-effect transistor FET2 in the amplitude modulator 4, for modulating in amplitude the very beginning of the signals passed through the tone-color filters 3. The output signal from the amplitude modulator 4 is thereafter supplied to the tone-color modulator 8 including R-C high pass filter with another field-effect transistor FET1 wherein the content of the harmonic components is shortly enhanced and decays faster than the fundamental under the control of the control signal formed in the wave-form shaper circuit 7. The output signal from the tone-color modulator 8 is then passed through the amplifier circuit 5 to the loud-speaker SP, whereby a sound simulating the sound of a plucked stringed instrument can be obtained.
When the keyboard K is operated in a legato manner, the control signal formed in the waveform shaper circuit 7 will be a substantially constant signal as described before with respect to the first embodiment of the invention, whereby the field-effect transistors FET1 and FET2 are constantly biased and the amplitude modulation and the tone-color modulation are both carried out by a constant extent, respectively, causing no variation in the level and tone-color of the output sound.
Although the invention has been described withh respect to preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications or alterations may be carried out without departing from the scope and spirit of the present invention. For instance, the field-effect transistors may well be substituted by ordinary transistors, or some of the transistors in the amplifier circuits may also be omitted for economy without losing the characteristic features of the present invention.
This invention relates to an electronic musical instrument wherein the start of the tone signal is emphasized prominently.
An electronic musical instrument having an upper keyboard, a lower keyboard, and a pedal keyboard is ordinarily played in such a manner that the upper keyboard assumes the melody part, the lower keyboard assumes the accompaniment part, and the pedal keyboard is used to play the bass part. However, in some cases, the melody part is played on the lower keyboard and the accompaniment part is played on the upper keyboard. Moreover, even in the ordinary case where the accompaniment is played on the lower keyboard, various modes of rendition, such as varying chords slowly for hamonization, intermitting chords quickly for rhythmic accompaniment, or playing a counter melody together with the rhythmic chords, are possible.
In all of the above described cases, the balance in volume between the melody part and the accompaniment part is not always constant, and a "manual balancer" knob must be operated during the rendition (playing) of the electronic musical instrument so that a desired tone balance is obtained between the melody part and the accompaniment part, such a procedure posing a difficulty in the playing of the musical instrument.
The above described difficulty can be obviated, if the volume of the sound (tone signal) be elevated remarkably at the initial instant or very start of the sound duration to exhibit a prominent attack. Furthermore, it is found that the sound of a string instrument of a type plucked by fingers or the like can be simulated by an electronic musical instrument wherein the tone level and tone color (especially harmonic components) of the sound be exaggerated at the initial instant of the sound creation.
SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to provide an electronic musical instrument wherein the tone signal is given a prominent attack at the very start portion of the tone signal existence.
Another object of the invention is to provide an electronic musical instrument whereby the necessity of the manipulation of the manual balancer knob during the performance of the musical instrument can be substantially eliminated even in the cases where the intensity of the accompaniment is to be varied widely depending on the playing manner.
Still another object of the invention is to provide an electronic musical instrument whereby the sound of the stringed musical instruments of a type plucked by fingers or the like can be simulated more effectively.
These and other objects of the present invention can be achieved by an electronic musical instrument comprising a music playing circuit arrangement having a tone signal passage, an amplitude modulator inserted in the tone signal passage, a detector connected to the tone signal passage for detecting the start of the tone signal being played, and a waveform shaper producing a percussive waveform signal upon receipt of the detected signal and controlling the modulator so that the start of the tone signal be percussively emphasized.
In another aspect thereof, the invention is directed to toward an electronic musical instrument comprising a music playing circuit arrangement having a tone signal passage, an amplitude modulator and a tone color modulator inserted in the tone signal passage, detector connected to the tone signal passage for detecting the start of the tone signal being played, and a waveform shaper producing a percussive waveform signal upon receipt of the detected signal and controlling the modulators in a way that the tone level is shortly enhanced and the tone color is shortly rendered rich in higher harmonics at the very start of the tone signal.
The nature, principle, and the utility of the present invention can be more clearly understood from the following detailed description of the invention when read in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals and characters.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a block diagram showing a circuit outline of an electronic musical instrument constituting a preferred embodiment of the present invention:
FIG. 2 is a detailed circuit diagram of the important part of the electronic musical instrument shown in FIG. 1;
FIG. 3 is an explanatory diagram of the envelope of the signal level variation in the embodiment shown in FIGS. 1 and 2;
FIG. 4 is a block diagram showing a circuit outline of another example of the electronic musical instrument constituting a second embodiment of the present invention; and
FIG. 5 is a detailed circuit diagram of the important part of the electronic musical instrument shown in FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is indicated an electronic musical instrument comprising tone generators 1 generating tone signals corresponding to desired notes, tone keyers 2 which are individually open or closed in accordance with the manipulation of the keys in, for instance, a lower keyboard K for permitting the tone signals from the tone generators to pass through the tone keyers 2, tone-color filters 3 for imparting tone-colors to the tone signals, an amplitude modulator 4 which varies the amplitude of the output signal delivered from the tone-color filters 3 responsive to a separately formed control signal, and an amplifier 5 which amplifies the output signal from the amplitude modulator 4 and delivers the output to a loudspeaker SP. These elements, 1, 2, K, 3, 4, 5, 6 and SP constitute a conventional music playing circuit arrangement having a tone signal passage. The electronic musical instrument also comprises a rectifying or detector circuit 6 which rectifies or detects the output signal from the tone keyers 2 for generating a square wave signal representing the envelope thereof, and a waveform shaper 7 which differentiates the output from the circuit 6 for forming a percussive pulse signal with an abrupt build-up and a subsequent gradual decay constituting the above mentioned separately formed gate signal.
In FIG. 2, there is illustrated in more detail the relation between the detector circuit 6, waveform shaper circuit 7, and the amplitude modulator 4 shown in FIG. 1, wherein the detector circuit 6 further includes an amplifier portion 6a.
The operation of this embodiment of the invention will be described with reference to FIGS. 1 and 2.
The tone generators 1 are constantly generating tone signals of the desired notes constituting octaves of musical scale, and these signals are selectively passed through the tone keyers 2 in accordance with the performance on the keyboard K. Each of the signals thus selected is imparted with a desired tone-color in the tone-color filters 3, and the amplitude of the output signal is controlled in the amplitude modulator 4 depending on the control signal, the amplitude being at a normal level when no control signal is supplied from the wave shpaer 7 and being enhanced to a prominent level when a control signal of the percussive waveform is supplied from the wave shaper 7. The output of the amplitude modulator 4 is amplified in the amplifier circuit 5 and converted into an audible sound through the loudspeaker SP.
If the keyboard K is operated in a staccato manner, the tone signals passed through the tone keyers 2 will be of a nature having sharply rising leading edges and frequent interruptions forming spaced-apart individual soundings with separate starts. Such signals are applied to the input terminal IN in the circuit diagram shown in FIG. 2, and one part thereof is passed through the tone-color filter 3 to the amplitude modulator 4, while the other part thereof is supplied to the amplifier portion 6a of the detector circuit 6. The amplifier portion 6a includes transistors Q1 and Q2 and amplifies the part of the signals to be supplied to the detector circuit 6 thereafter. The detector circuit 6 includes a transistor Q3 which acts as a class B amplifier only picking up the positive portions of the tone signals. The positive portions of the signals are thereafter supplied to the waveform shaper circuit 7. The waveform shaper circuit 7 includes a transistor Q4 provided with a differentiation circuit having a capacitor C1 and a resistor R2 and a by-passing resistor R1 at the output side thereof. As a result, when the sharply rising staccato renditioned signals arrive at the waveform shaper circuit 7, the sharply rising leading edge of every signal sounding is differentiated by the differentiation circuit, and a triangular pulse thus obtained is superposed onto a voltage obtained through the by-passing resistor, as indicated in FIG. 3.
When a control signal thus obtained is supplied to the gate of a field-effect transistor FET included in the amplitude modulator 4, the effective resistance of the field-effect transistor FET is varied in accordance with the control signal, and the extent of modulation in the amplitude modulation transistors Q5 and Q6 is also varied in accordance with the control signal.
Thus, when the output signal from the tone keyers 2 is supplied to the amplitude modulator 4 after it has passed through the tone-color filters 3, the signal is amplitude-modulated under the control of the control signal supplied to the gate of the field-effect transistor FET, and is further amplified in a transistor Q7. The output signal from the amplitude modulator 4 inclusive of the transistor Q7 is delivered from the output terminal OUT and sent through the amplifier circuit 5 to the loudspeaker SP. From the loudspeaker SP, a crisp and staccato sound can be obtained because of the above described organization of the circuitry. The level of the initially rising-up portion of the output tone is preferably set at a value 3 to 6 dB higher than the rest of the sustaining part of the tone signal.
In the case where the keyboard K is operated in a legato manner, no initial rising portion every tone start exists in the output tone signal from the tone keyers 2 except that obtained at the time of the first key is depressed initially, whereby the output signal from the waveform shaper circuit 7 will be made constant all the rest of time, and the resultant sound from the loudspeaker SP will not be imparted with the above described enhancing effect.
For this reason, when it is desired that the melody part of music be played on the lower keyboard on which the accompaniment part has been so far played, a mere rendition in a staccato manner will sufficiently elevate the apparent sound level of the melody part now played on the lower keyboard, and the conventional manipulation of the manual balancer knob during the performance will be unnecessary.
The above described circuitry of the electronic musical instrument according to the present invention, with slight modification, may also be utilized for simulating the sound of certain kinds of stringed instruments.
When the sound of a string instrument such as a guitar, having strings plucked by fingers or the like, is analyzed, it turned out that the envelope of the sound rises sharply at its initial portion of the period and then decays in a non-linear manner, and that the content of the higher harmonics decays far faster than the fundamental.
Such features of the sound of the string instrument can be obtained in the circuit of an electronic musical instrument as shown in FIGS. 4 and 5, which constitutes another embodiment of the present invention.
Referring to FIG. 4, there is indicated the circuit of an electronic musical instrument comprising tone geenerators 1 for generating desired notes, tone keyers 2 for selectively passing some of the notes to the subsequent stage under the control of the keyboard K, a tone-color filters 3, an amplitude modulator 4 which modulates in amplitude the output signal form the tone-color filters 3 depending on a signal separately formed in response to the operation of the keyboard K, an amplifier circuit 5 and a loudspeaker SP, a detector circuit 6, and a waveform shaper circuit 7, all being organized and connected in the similar manner as in the first embodiment of the invention except that a minor change is made in the circuit 7, and a tone-color modulator 8 is further provided between the amplitude modulator 4 and the amplifier.
Referring to FIG. 5, there is illustrated in more detail the relation between the detector circuit 6, waveform shaper circuit 7, and the amplitude modulator 4 shown in FIG. 4, wherein the detector circuit 6 includes an amplifier portion 6a. It will be apparent in the figures that, in this example, a resistor R1 by-passing a capacitor C1 in the circuit 7 is omitted, and another capacitor C2 is provided in parallel with a biasing resistor R2, so that the steady portion in the control signal is thereby eliminated and the inpulsive portion thereof is exaggerated. Furthermore, in the circuit of the second example, a tone-color modulation circuit 8 is provided between the amplitude modulator 4 and the amplifier circuit 5 as described above and is connected in such a manner that the output signal from the amplitude modulator 4 is supplied to the input side of the tone-color modulator 8, and the higher harmonic components among the signal thus supplied are emphasized shortly upon receipt of the control signal obtained from the waveform shaper circuit 7, and come back to the normal non-emphasized state.
With the above described organization of the circuit of this example since all of the circuit members from 1 through 6 are equal to the circuit members of the corresponding reference numerals in the first example, the operation of this part of the circuit is quite similar to that described hereinbefore.
Thus, when the keyboard K is operated in a staccato manner, the sound signals passed through the tone keyers 2 are supplied at the input terminal IN of FIG. 5, and one part thereof is passed through the tone-color filters 3 to the amplitude modulator 4, and the other part of the sound signals is passed to the detector circuit 6. In the detector circuit which acts as a class B amplifier, only the positive parts of the signals are picked up and supplied to the waveform shaper circuit 7.
In the waveform shaper circuit 7, the sharp leading edge of each of the signals is differentiated by the differentiation circuit, and a triangular pulse having a sharply rising leading edge is obtained. This signal is applied as a control signal to the gate terminal of a field-effect transistor FET2 in the amplitude modulator 4, for modulating in amplitude the very beginning of the signals passed through the tone-color filters 3. The output signal from the amplitude modulator 4 is thereafter supplied to the tone-color modulator 8 including R-C high pass filter with another field-effect transistor FET1 wherein the content of the harmonic components is shortly enhanced and decays faster than the fundamental under the control of the control signal formed in the wave-form shaper circuit 7. The output signal from the tone-color modulator 8 is then passed through the amplifier circuit 5 to the loud-speaker SP, whereby a sound simulating the sound of a plucked stringed instrument can be obtained.
When the keyboard K is operated in a legato manner, the control signal formed in the waveform shaper circuit 7 will be a substantially constant signal as described before with respect to the first embodiment of the invention, whereby the field-effect transistors FET1 and FET2 are constantly biased and the amplitude modulation and the tone-color modulation are both carried out by a constant extent, respectively, causing no variation in the level and tone-color of the output sound.
Although the invention has been described withh respect to preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications or alterations may be carried out without departing from the scope and spirit of the present invention. For instance, the field-effect transistors may well be substituted by ordinary transistors, or some of the transistors in the amplifier circuits may also be omitted for economy without losing the characteristic features of the present invention.