AN ELECTRONIC ORGAN WITH AUTOMATIC CHORD AND BASS SYSTEMS
United States Patent 3708602
In an electronic musical instrument having an upper keyboard for melody performance, a lower keyboard for chord performance and a pedal keyboard for bass performance, there is interposed a first gate circuit in the channel of the lower keyboard tone signals and a second gate circuit in the channel of the bass tone signals, and there is also provided a generator of rhythm pattern pulses which open the gate circuits in accordance with the rhythm pattern. On this instrument, chord and bass performance is carried out in desired rhythm pattern by merely depressing keys continuously instead of intermittently.
US Patent References:
PIANO KEYBOARD TYPE ELECTRONIC MUSICAL INSTRUMENT HAVING A BASS PEDAL AND SINGLE CONTINUOUS KEYBOARD
Omura et al. - August 1969 - 3461217
SWITCHING DEVICE FOR ELECTRONIC MUSICAL INSTRUMENT WITH SUSTAIN EFFECT
Teranishi - October 1970 - 3535972
MUSICAL INSTRUMENT RHYTHM SYSTEM HAVING PROVISION FOR INTRODUCING AUTOMATICALLY SELECTED CHORD COMPONENTS
Tennes - March 1971 - 3567838
AUTOMATIC TONE GENERATING SYSTEM FOR AN ELECTRONIC ORGAN
Maynard - December 1970 - 3546355
Electronic musical instrument
Gibbs et al. - September 1964 - 3150228
PIANO KEYBOARD TYPE ELECTRONIC MUSICAL INSTRUMENT HAVING A BASS PEDAL AND SINGLE CONTINUOUS KEYBOARD
Omura et al. - August 1969 - 3461217
SWITCHING DEVICE FOR ELECTRONIC MUSICAL INSTRUMENT WITH SUSTAIN EFFECT
Teranishi - October 1970 - 3535972
MUSICAL INSTRUMENT RHYTHM SYSTEM HAVING PROVISION FOR INTRODUCING AUTOMATICALLY SELECTED CHORD COMPONENTS
Tennes - March 1971 - 3567838
AUTOMATIC TONE GENERATING SYSTEM FOR AN ELECTRONIC ORGAN
Maynard - December 1970 - 3546355
Electronic musical instrument
Gibbs et al. - September 1964 - 3150228
Application Number:
05/084979
Publication Date:
01/02/1973
Filing Date:
10/29/1970
View Patent Images:
Export Citation:
Assignee:
Nippon Gakki Seizo Kabushiki Kaisha (Hamamatsu-shi, JA)
Primary Class:
Other Classes:
84/715, 84/713, 984/349
International Classes:
G10H1/38; G10F1/00
Field of Search:
84/1.01,1.03,1.17,1.24,DIG.2,1.13,1.19,1.26 307/239,248,253-254
US Patent References:
Other References:
page 192 from "Introduction to Electronic Systems, Circuits, and Devices" D. O. Pederson, J. J. Studer, J. R. Whinnery, McGraw-Hill Book Co., New York, 1966..
Primary Examiner:
Wilkinson, Richard B.
Assistant Examiner:
Weldon U.
Claims:
What is claimed is
1. An electronic musical instrument comprising:
2. An electronic musical instrument comprising:
1. An electronic musical instrument comprising:
2. An electronic musical instrument comprising:
Description:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic musical instrument and more particularly to an electronic musical instrument such, for example, as an electronic organ provided with an upper keyboard for melody performance, a lower keyboard for chord performance and a pedal keyboard for bass performance.
On an electronic organ having upper, lower and pedal keyboards, there is generally played a melody performance by operation of the upper keyboard with the right hand, a chord performance by operation of the lower keyboard with the left hand and a bass performance by operation of the pedal keyboard with the left foot. In this case, the left hand chord performance and the left foot bass performance are commonly conducted with a certain rhythm pattern, like that of a march or a waltz. However, the chord and bass performances by the left hand and left foot require considerable skill, because they have to be played in conjunction with the melody performance by the right hand. Particularly, a beginner finds it extremely difficult to carry out a rhythm accompaniment of chord and bass exactly conforming with a melody performance. Accordingly, it has been demanded that such electronic organ be so designed as to enable a beginner at the initial stage of practice easily to play a chord and/or bass performance simply by operating the lower keyboard continuously with the left hand during a melody performance on the upper keyboard with the right hand, even when he is still unable to operate the lower and/or pedal keyboard rhythmically.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an electronic musical instrument which enables a chord or bass performance to be automatically played in a predetermined rhythm simply by continuously depressing the keys of either of the lower and pedal keyboards.
Another object of the invention is to provide an electronic musical instrument which automatically gives desired chord and bass performances simply by continuously depressing the proper keys of the lower and pedal keyboards.
Still another object of the invention is to provide an electronic musical instrument which enables chord and bass performances to be automatically played with a predetermined rhythm simply by continuously depressing the keys of the lower keyboard in accordance with a desired chord.
An electronic organ comprises tone generators; key switch circuits associated with the upper, lower and pedal keyboards for selectively keying signals from the tone generators; tone coloring filters for converting signals selected by the key switches of the upper, lower and pedal keyboards to musical tones having predetermined tone colors; circuits for mixing and amplifying musical tones from the filters; and an electro-acoustic transducer for converting amplified musical tone signals to sounds.
One of the characteristic features of the present invention is that there is provided gating means in at least one of the two channels extending from the key switch circuits of the lower and pedal keyboards to the amplifying means, which gating means is supplied with desired rhythm pattern timing pulses from a generator thereof. Depression of the keys of a keyboard associated with the channel having the gating means causes the means to be continuously supplied with the selected signals from the tone generator. Timing pulses from the generator open the gating means at a predetermined rhythm interval, thereby producing musical tones having desired rhythm patterns from a loud-speaker.
Another characteristic feature of the present invention is that there is included means for automatically detecting the type of the chord when the keys of the lower keyboard are depressed for a chord performance and there is further provided gating means in each of the lower and pedal keyboard channels. The chord detecting means permits the gating means of the pedal keyboard channel to be continuously supplied with bass tone signals corresponding to two main notes, that is, the root and the fifth of the chord played on the lower keyboard. A chord depression on the lower keyboard continuously impresses the gating means disposed in the channel thereof with signals representing the aforesaid two main notes included in the chord. Since the pulse generator supplies both gating means with rhythm pattern timing pulses conforming with the chord and bass performances, mere continuous depression of the keys on the lower keyboard enables a chord performance and a bass performance with the root and fifth of the chord to be automatically played.
Still another characteristic feature of the present invention is that there is provided means which, upon depression of the keys on the lower keyboard for a chord performance, detects notes of the highest and lowest pitches included in the chord performance, and supplies bass tone signals corresponding to those notes to the gate circuit of the pedal keyboard channel. When the gate circuits of the lower and pedal keyboard channels are supplied with rhythm pattern timing pulses from the generator, there is automatically conducted a bass performance by the highest and lowest notes of the chord as well as a chord performance.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a block circuit diagram of an electronic musical instrument according to an embodiment of the present invention;
FIGS. 2A, 2B and 2C are musical notations for explaining the operation of the electronic musical instrument of FIG. 1;
FIG. 3 is a block circuit diagram of an electronic musical instrument according to another embodiment of the invention;
FIG. 4 is a block circuit diagram of an electronic musical instrument according to still another embodiment of the invention;
FIGS. 5A, 5B and 5C are musical notations for explaining the operation of the electronic musical instrument of FIG. 4;
FIG. 6 is a circuit diagram of the chord detector of FIG. 5;
FIG. 7 represents a base selector and gate circuit of FIG. 5;
FIG. 8 is a modification of the circuit of FIG. 7;
FIG. 9 is a chart illustrating the components of chords in the key of C;
FIG. 10 is a block circuit diagram of an electronic musical instrument according to a further embodiment of the invention; and
FIG. 11 indicates the arrangement of the priority switcher of FIG. 10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A schematic electronic organ system is included in FIG. 1 illustrating one embodiment of this invention. The system includes tone generators 1, outputs from which are branched off to an upper keyboard channel 2, lower keyboard channel 3 and pedal keyboard channel 4. The upper keyboard channel 2 comprises an upper keyboard 5 including associated key switch circuits for selectively keying signals from the tone generators 1 and tone coloring filters 8 for converting signals selected by the key switch circuits 5 to musical tone signals having proper timbres. Like the upper keyboard channel 2, the lower and pedal keyboard channels 3 and 4 respectively comprise a lower keyboard 6 and a pedal keyboard 7 including associated key switch circuits for selectively keying signals from the tone generators 1 and tone coloring filters 9 and 10 for converting signals selected by the key switch circuits 6 and 7 to musical tone signals having proper timbres. The key switch circuits of the keyboard channel are supplied with tone signals from the tone generators 1 which have frequencies corresponding to the notes to be played on the keyboard. Musical tone signals from the tone coloring filters are mixed and conducted to an amplifier. Musical tone signals thus amplified actuate a loud-speaker 12. The aforesaid electronic organ system is already known and will be fully understood without detailed description.
In an embodiment of the present invention, the lower and pedal keyboard channels 3 and 4 have gate circuits 13 and 14 positioned between the respective switch circuits 6 and 7 and the tone coloring filters 9 and 10. There is further provided a rhythm pattern pulse generator 15, which comprises a pulse generator 16 and timing pulse encoders 17 and 18. Timing pulses from the encoders 17 and 18 are supplied to the gate circuits 13 and 14 to open them in accordance with the rhythm patterns represented by the pulses. The pulse generator 16 comprises, for example, an astable multivibrator having a variable oscillation frequency and a ring counter formed of a necessary number of flip-flop circuits which are impressed with output pulses from the astable multivibrator. As is well known, there are drawn out pulses in turn from the flip-flop circuits constituting the ring counter. The timing pulse encoder may consist of a diode matrix circuit. In this case, the column lines, for example, of the matrix circuit to be supplied in turn with pulses from the pulse generator 16 have the same number as the flip-flop circuits constituting the ring counter. On the other hand, the row lines of the matrix circuit are provided in the same number as desired rhythm patterns. At the intersections defined by one row line with the column lines are connected diodes disposed in accordance with a predetermined rhythm pattern. From the row lines stored with different rhythm patterns, is selected one row line with desired rhythm pattern. The rhythm pattern pulses from the row lines are conducted to the gate circuit after being shaped by a differentiating circuit having a proper time constant. Details of such rhythm pattern pulse generator and other processes relative thereto are already clearly set forth in the U.S. Pat. Nos. 3,255,292, 3,358,068 and 3,383,452.
In the embodiment of FIG. 1, the upper keyboard plays a melody performance as usual. On the lower keyboard, there are continuously depressed a plurality of keys corresponding to notes constituting a desired chord in conjunction with the melody performance. On the pedal keyboard, there is depressed a key corresponding to, for example, the root of the chord. Accordingly, the gate circuits 13 and 14 disposed in the lower and pedal keyboard channels 3 and 4 are normally supplied with signals corresponding to the pitches of notes represented by the depressed keys. The gate circuits 13 and 14 are impressed by the rhythm pattern pulse generator 15 respectively with a sequence of pulses having a rhythm pattern conforming with a melody performance and are opened only upon the impression. From the gate circuits 13 and 14, therefore, there are intermittently drawn out signals corresponding to the rhythm pattern. Signals from the pedal keyboard channel are bass tone signals having a frequency one octave lower than that of the root of the chord.
The aforementioned matter will be more clearly understood by reference to FIGS. 2A, 2B and 2C. FIG. 2C represents chords and basses to be played on the lower and pedal keyboards respectively. As apparent from FIG. 2C, there are played on the lower keyboard four beats of the chord C in the first measure, four beats of the chord F in the second measure, four beats of the chord G in the third measure and again the chord C in the fourth measure, and there are played on the pedal keyboard notes C, F and G constituting the root of each chord at a period twice that of the notes played on the lower keyboard.
According to an embodiment of the present invention, where there are continuously depressed, for a whole note length, the keys of the lower keyboard corresponding to the notes G, C and E constituting the chord C in the first measure as shown in FIG. 2B, and the key of the pedal keyboard corresponding to the note C constituting the root of the chord C, then the gate circuits 13 and 14 are respectively supplied with the tone signals corresponding to the aforementioned notes to be gated and at the same time with sequences x and y of pulses having the rhythm patterns of FIG. 2A. Thus there are produced musical tones having the rhythm of FIG. 2C from the lower and pedal keyboard channels through a loud-speaker 12. Where there are continuously depressed for a whole note length in the second measure the keys of the lower keyboard corresponding to the notes A, C and F constituting the chord F and the key of the pedal keyboard corresponding to the note F constituting the root of the chord F, then there are sounded by the rhythm pattern pulses of FIG. 2A these musical tones having the same rhythm pattern as that of the first measure. Thus continuous depression of the keys on the lower and the pedal keyboards enables the desired chord and bass performances to be automatically played in the desired rhythm by the action of the rhythm pattern pulses and the gate circuits.
In the embodiment of FIG. 1, there is provided a gate circuit in both lower and pedal keyboard channels. Such arrangement permits the right hand to be used exclusively in operating the upper keyboard for a melody performance, and the left hand and foot to operate the lower and pedal keyboards with great ease. However, the gate circuit may be formed only in either of the lower and pedal keyboard channels. If in this case, the player engages himself mainly in the operation of, for example, the lower keyboard, he will be able easily to play the other pedal keyboard at the same time, in the channel of which there is disposed a gate circuit. Alternatively, there may be formed a gate circuit in both channels in advance, and either or both of the gate circuits may be selectively used according to the object of practice. For elevation of performance effect, the embodiment of FIG. 1 may be developed into that of FIG. 3, wherein the gate circuits 21 and 22 are normally supplied with output signals from, for example, two percussion tone generators 19 and 20 incorporated in an electronic organ and further controlled by rhythm pattern pulses from timing pulse encoders 23 and 24 specifically included in the rhythm pattern pulse generator 15, for the performance of the rhythm section of the band music. The same parts of FIG. 3 as those of FIG. 1 are denoted by the same numerals and description thereof is omitted.
If an electronic organ is so designed for simplification of its operation as to permit a bass performance to be automatically conducted in the form conforming with a chord performance on the lower keyboard simply by operation of the lower keyboard which is originally intended to play a chord performance, then there will be offered greater convenience for a beginner.
The embodiment of FIG. 4 has been developed to attain the aforementioned object. The same parts of FIG. 4 as those of FIG. 1 are denoted by the same numerals. The embodiment of FIG. 4 further includes a bass selector 25 and a chord detector 26. This bass selector 25 corresponds to the pedal key switch circuits 7 of FIG. 1. The bass selector 25 is supplied with the same bass tone signals as the pedal key switch circuits 7, so that the channel including the selector 25 is also hereinafter referred to as "the keyboard channel." The chord detector 26 is provided for detecting the type of the chord being played on the lower keyboard. Detected outputs from the chord detector 26 enable the aforesaid bass selector 25 to select those bass tone signals from the tone generator 1 which represent notes corresponding to the root and the fifth contained in the chord being played on the lower keyboard. As in the embodiment of FIG. 1, there are formed gate circuits 13 and 14 in the lower and pedal keyboard channels 3 and 4. The gate circuit 13 of the lower keyboard channel 3 is supplied for an automatic rhythmic performance of the chords with a rhythm pattern pulse or timing pulse from the timing pulse encoder 17 included in the rhythm pattern pulse generator 15. The gate circuit 14 provided in the pedal keyboard channel 4 is supplied from the timing pulse encoder 18 with two kinds y and z of rhythm pattern pulses or timing pulses for the root and the fifth selected by the bass selector 25 in order to carry out an automatic rhythmic performance of the basses.
There will now be described by reference to FIGS. 5A, 5B and 5C, the operation of the embodiment of FIG. 4. FIG. 5C illustrates a chord performance on the lower keyboard and a bass performance on the pedal keyboard which are to be played in conjunction with a melody performance on the upper keyboard. As apparent from FIG. 5C, there are to be played on the lower keyboard a chord C in the first measure, a chord F in the second measure, a chord G 7 in the third measure and again the chord C in the fourth measure. On the pedal keyboard, there are to be successively played in the first measure the root note C and the fifth note G of the chord C, in the second measure the fifth C and the root F of the chord F, in the third measure the fifth D and the root G of the chord G 7 , and in the fourth measure the root C of the chord C. In the embodiment of FIG. 4, it is only required for a chord performance to continuously depress the keys of the lower keyboard corresponding to the chord notes of each measure for the whole measure length as shown in FIG. 5B. In the meantime, the gate circuit 13 of the lower keyboard channel 3 is supplied from the timing pulse encoder 17 with a sequence x of rhythm pattern pulse for a chord performance as illustrated in FIG. 5A, causing a chord performance shown in FIG. 5C to be automatically played as in the embodiment of FIG. 1. The gate circuit 14 of the pedal keyboard channel 4 is also supplied with signals representing the root and the fifth of the respective chords and a sequence y of rhythm pattern pulse for the root and a sequence z of rhythm pattern pulse for the fifth from the timing pulse encoder 18, thereby enabling an automatic bass performance shown in FIG. 5C which would otherwise have to be effected by the actual complicated operation of the pedal keyboard by the player himself.
In the embodiment of FIG. 1, the pedal keyboard was described as playing only the root of the chord which was to be played by the lower keyboard. However, the embodiment of FIG. 4 permits a bass performance to be automatically conducted by the root and the fifth of the chord, providing a more prominent musical effect.
There will now be described by reference to FIG. 6 the chord detector of FIG. 4. The chord detector 26 consists of a matrix circuit comprising a plurality of column lines, row lines and diodes positioned at the prescribed intersections of both lines. The matrix circuit has twelve column lines L 1 to L 12 corresponding to the notes of one octave, the ends on one side of the column lines being grounded by normally open key switches S 1 to S 12 operated by the respective keys of the lower keyboard. The switches actuated by the keys corresponding to the same notes in the different octaves are respectively connected to the same common column lines included in the matrix circuit. The ends on the other side of the column lines are connected through a resistor 27 to one end of a common power source 28, the other end of which is grounded. The matrix has the same number of row lines 0 1 , 0 2 , 0 3 , . . . as the kinds of chords to be played by the lower keyboard. FIG. 6 indicates seven row lines representing chords C, F, G 7 , A m , D m , D 7 and B♭. At the prescribed intersections between the row lines denoting these chords and column lines are connected diodes in the forward direction with respect to the polarity of the power source 28 to which the column lines are connected to detect, for example, chord C, there are connected diodes D of the indicated polarity to three intersections defined by row line 0 1 with column line L 1 , connected to switch S 1 operated by the key of the lower keyboard corresponding to note C included in chord C, column line L 5 connected to switch S 5 . corresponding to note E and column line L 8 connected to switch S 8 corresponding to note G.
Referring to the operation of the aforesaid chord detector, the diodes are connected to the intersections of the row lines and column lines in the forward direction with respect to the positive source voltage, so that the potential of the detection terminal of the row line is normally kept positive. Depression of the keys of the lower keyboard corresponding to, for example, notes C, E and G causes switches S 1 , S 5 and S 8 to be closed and in consequence column lines L 1 , L 5 and L 8 to be grounded. Accordingly, the power source 28 is short-circuited with column lines L 1 , L 5 and L 8 by the resistor 27, preventing row line 0 1 connected to column lines L 1 , L 5 and L 8 by the diodes from being impressed with voltage, so that the potential of the detection terminal of row line 0 1 , that is, the voltage across the resistor 30 is reduced to zero. At this time, the potentials of the detection terminals of the other row lines are still kept positive. From the fact that the potential of the detection terminal of row line 0 1 associated with the chord C was changed from positive to zero, it is determined that the chord performed by operation of the lower keyboard was C. The detected output controls the bass selector 25. This selector 25 may be constructed as illustrated in FIG. 7. The bass tone signals, for example, of notes C and G corresponding to the root and the fifth of chord C are directly supplied from the tone generator to the transistors T 1 and T 2 without passing through the key switches operated by the pedal keyboard, and the emitter of both transistors T 1 and T 2 is grounded by the chord C detecting circuit 26c. The chord C detecting circuit is included in the above-mentioned chord detector. For simplification, three switches S 1 , S 5 and S 8 and three diodes are indicated by one switch S c and one diode D c respectively.
When chord C is not detected, namely, when the switch S c of the chord C detector is opened, the voltage of the emitters of transistors T 1 and T 2 supplied by the power source 28 is set at a higher level than the base bias voltage, thereby bringing the transistors T 1 and T 2 into an inoperative stage. Upon detection of chord C, namely, when the switch S c of the chord C detector is closed, the emitters of transistors T 1 and T 2 are disconnected from the power source 28 and grounded through the resistor 30, bringing the transistors T 1 and T 2 into an operative state. Accordingly, signals representing the root and the fifth of the chord C supplied to the base of transistors T 1 and T 2 are drawn out from the collectors and conducted to gate circuits 14A and 14B intended for the root and the fifth respectively. The emitters of transistors T 3 and T 4 constituting the gate circuits 14A and 14B are supplied with rhythm pattern pulses y and z for the root and the fifth as shown in FIG. 5A. The rhythm pattern signals consist of a sequence of negative pulses which normally have a positive potential and assume a low or zero voltage when they are pulsed. Normally, therefore, the positive potential supplied to the emitter of the transistors T 3 and T 4 is maintained at a higher level than the base bias voltage, thereby bringing the gate circuits 14A and 14B into an inoperative state. When negative rhythm patterns are introduced, the emitter potential decreases from the base potential, actuating or opening the gate circuits 14A and 14B. Thus only when there are introduced negative pulses, there are drawn out musical tone signals from the gate circuits 14A and 14B. Musical tone signals corresponding to the root and the fifth of the chord C are mixed and conducted to the tone coloring filter 10. The bass selector 25 further includes transistors T 5 and T 6 and so on which are supplied with tone signals corresponding to the roots and the fifths of other chords. The emitters of transistors T 5 and T 6 are grounded by a circuit for detecting the chord C♯. Outputs from the transistors T 1 and T 5 and so on supplied with tone signals corresponding to the roots of the chords are conducted to the common gate circuit 14A for the root, while outputs from the transistors T 2 and T 6 and so on supplied with tone signals corresponding to the fifths of the chords are impressed on the common gate circuit 14B for the fifth. The function of the bass selector 25 consists in previously supplying a pair of transistors with bass tone signals corresponding to the root and the fifth of the one chord to be detected at a time by the chord detecting circuit 26 and simultaneously controlling the paired transistors by the detected output from the chord detector.
In the embodiment of FIG. 7, the bass selector and the gate circuits are separately arranged. However, the transistors of the bass selector 25 supplied with tone signals corresponding to the root and the fifth of the chord may be made concurrently to act as a gate circuit. Such embodiment is given in FIG. 8. There is provided a diode D 8 between the emitters of the paired transistors T 1 and T 2 of FIG. 7 controlled in common by the chord C detector 26c and the chord detector 26c in the opposite direction to the base-emitter diode included in the transistors, and there is also disposed a resistor R 8 between the emitters of transistors T 1 and T 2 and the earth. Timing pulses y and z are supplied respectively to the emitters of transistors T 1 and T 2 through a diode D 9 disposed in the opposite direction to the baseemitter diode. When chord C detector 26c becomes inoperative, the emitters of transistors T 1 and T 2 are kept at a positive potential by the power source 28 so as to prevent the transistors from being jointly operated. Upon actuation of the chord C detector 26c, the emitters of the transistors are disconnected from the power source 28. Even though the transistors tend to be actuated due to their emitters being grounded through the resistor R 8 , the emitters of the transistors are still kept at a positive potential and do not become operative during the period of positive potential included in a sequence of timing pulses supplied to the emitter through the diode D 9 . During the period of negative pulses in which the potential is reduced, the emitter potential of transistor T 1 for example decreases from its base potential, so that the transistor T 1 is brought into an operative state and there are drawn output signals from the collector of transistor T 1 . It will be apparent that the transistors T 1 and T 2 are independently brought to an operative state by the respective timing pulses.
In the chord detecting circuit of FIG. 6, there were connected three diodes to the row lines so as to have each chord distinguished by the three notes included therein. It will be apparent, however, that where the chord is constitutied by four notes, the row line may be provided with four diodes. For further simplification, the detection of the chord may be effected only by two notes, that is, the root and the fifth of the chord. In this case, there are provided diodes only at the intersections defined, for example, by the raw line 0 1 with column line L 1 corresponding to the note C constituting the root of the chord C and column line L 8 corresponding to the note G constituting the fifth of the chord C. In FIG. 6, the chord detector is designed to detect chord C by the notes C, E and G. As apparent from FIG. 9, however, there are other chords C, C 6 , and C M7 each of which contains the notes C, E and G. Detection of these chords, therefore, produces common detected output. There are still other chords C, Cm, C 6 , Cm 6 , C 7 , and Cm 7 , each of which contains the notes C and G. Therefore, in the case of detecting the chords above mentioned including two common notes C and G the chord detector produces a common detected output. Since, however, there is no need for the beginner to distinguish between the aforementioned chords, detection of the chords by only two notes will not present any practical difficulties.
The embodiment of FIG. 4 enables the chord detector to distinguish the kind of chord played by the lower keyboard and also a bass performance to be conducted by bass tone signals corresponding to the root and the fifth of the chord. Consequently the arrangement becomes exceedingly complicated as shown in FIGS. 6 and 7. In fact, bass tones played by the pedal keyboard often represent the outer part tones of the chord played with the left hand on the lower keyboard, namely, the highest and the lowerst notes of the chord. Therefore, it is not always necessary to rely on the root and the fifth for a bass performance.
FIG. 10 denotes an embodiment wherein, during the chord performance by the lower keyboard, there are detected the highest and the lowest pitch notes of the chord and the performance is conducted by bass tone signals corresponding to the highest and lowest notes. In the embodiment of FIG. 10 there is used, instead of the chord detector 26 and the bass selector 25, a priority switcher 31 which is normally supplied with bass tone signals from the tone generator 1 and operated interlockingly with the lower keyboard 6, namely, contains a plurality of switches operated by the lower keyboard, thereby preferentially selecting the highest and the lowest notes of the chord played on the lower keyboard. The other parts of FIG. 10 are of the same arrangement as in FIG. 4.
The priority switcher 31 comprises, as shown in FIG. 11, first and second groups 32 and 33 constructed by first and second switches respectively which are operated by the same key of the lower keyboard. Each switch constituting the first switch group 32 has a movable contact 35 connected with a normally closed fixed contact of a switch positioned in the adjacent lower tone section, a normally closed contact 36 and a normally open fixed contact 37 connected with the tone generator, and each switch constituting the second switch group 33 has a normally closed fixed contact 38, a movable contact 39 connected with a normally closed fixed contact of a switch positioned in an adjacent higher note section and a normally open fixed switch 40 connected with the tone generator along with the normally open contact 37 of the switch actuated by the same key of the lower keyboard. The movable contact 35 of the switch, that is, the switch actuated by the key corresponding to the note C in the drawing, positioned in the lowest tone section of first switch group 32 for selecting the lowest bass tone signal and the movable contact 39 of the switch, that is, the switch actuated by the key corresponding to the note B, positioned in the highest section of the second switch group 33 for selecting the highest bass tone signal are connected to the gate circuit 14 shown in FIG. 10, as the bass tone input signals.
There will now be described the operation of the switcher of FIG. 11. Depression of the keys of the lower keyboard corresponding to the notes C, E and G to play for example, chord C actuates six corresponding switches. Namely, the movable contact of each switch connected to a normally closed fixed contact is switched to a corresponding normally open fixed contact connected to the tone generator. While the movable contact 35 of each of those of the first group switches 32 which are associated with the notes C, E and G is switched from a corresponding normally closed contact 36 to a corresponding normally open contact 37, the movable contact 35 of the switch associated with the note C is switched to a corresponding normally open fixed contact 37 connected to the tone generator, so that the gate circuit 14 is supplied with a tone signal representing the pitch of the note C. On the other hand, among the switches of the second group 33, the movable contact 39 of each of those associated with the notes C, E and G is switched from a corresponding normally closed fixed contact 38 to a corresponding normally open fixed contact 40. In this case, the movable contact 39 of that of these three switches which is associated with the highest note, namely, the note G is switched from the corresponding normally closed fixed contact 38 of a switch representing a note next higher than G to a corresponding normally open fixed contact 40 connected to the tone generator. Thus a tone signal having the pitch of the note G passes through the intermediate switches and is finally drawn out from the movable contact 39 of a switch representing the highest note B and supplied to the gate circuit 14. In the performance of chord C by the lower keyboard, tone signals having the pitches of the lowest note C and the highest note G included in the chord C are drawn out and supplied to the gate circuit 14. This gate circuit 14 supplied with tone signals representing the highest and lowest notes may be constructed in the same manner as the gate circuits 14A and 14B for the root and the fifth illustrated in FIG. 7.
Referring to FIG. 11, each group of switches constituting the switcher consists of 12 switches so as to match twelve notes included in one octave. Since, however, the lower keyboard includes more than 12 keys, the group practically has the same number of switches as the keys. The switches associated with the same note are arranged parallel. Namely, the movable contacts, normally closed fixed contacts and normally open fixed contacts of these switches are respectively connected to each other.
According to the foregoing description, the base tone signal denoting the lowest note C of chord C represents its root and the bass tone signal indicating the highest note G of the chord C represents its fifth. Depending on the inversions of chord played, however, the bass tone signals do not always bear such relationship. Where it is desired to take out a root and a fifth as the lowest and highest notes respectively, it is only required to operate the lower keyboard in such a manner that the lowest and highest notes represent the root and the fifth of a chord, i.e. the chord in the root position.
Further, the gate circuit 14 supplied with signals of the lowest and the highest notes selected by the priority switcher 31 of FIG. 8 is impressed, as in the embodiment of FIG. 4, with rhythm pattern pulses x and y from the timing pulse encoder 18 of the rhythm pattern pulse generator 15, thus enabling a rhythm performance by bass tones to be automatically conducted without operating the pedal keyboard.
It will be apparent that if there are incorporated all the aforementioned embodiments of the present invention in a single electronic organ in such a manner that the function or feature of each embodiment can be freely selected by a beginner, then there will be the advantage of permitting him to conduct various forms of practice.
The present invention relates to an electronic musical instrument and more particularly to an electronic musical instrument such, for example, as an electronic organ provided with an upper keyboard for melody performance, a lower keyboard for chord performance and a pedal keyboard for bass performance.
On an electronic organ having upper, lower and pedal keyboards, there is generally played a melody performance by operation of the upper keyboard with the right hand, a chord performance by operation of the lower keyboard with the left hand and a bass performance by operation of the pedal keyboard with the left foot. In this case, the left hand chord performance and the left foot bass performance are commonly conducted with a certain rhythm pattern, like that of a march or a waltz. However, the chord and bass performances by the left hand and left foot require considerable skill, because they have to be played in conjunction with the melody performance by the right hand. Particularly, a beginner finds it extremely difficult to carry out a rhythm accompaniment of chord and bass exactly conforming with a melody performance. Accordingly, it has been demanded that such electronic organ be so designed as to enable a beginner at the initial stage of practice easily to play a chord and/or bass performance simply by operating the lower keyboard continuously with the left hand during a melody performance on the upper keyboard with the right hand, even when he is still unable to operate the lower and/or pedal keyboard rhythmically.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an electronic musical instrument which enables a chord or bass performance to be automatically played in a predetermined rhythm simply by continuously depressing the keys of either of the lower and pedal keyboards.
Another object of the invention is to provide an electronic musical instrument which automatically gives desired chord and bass performances simply by continuously depressing the proper keys of the lower and pedal keyboards.
Still another object of the invention is to provide an electronic musical instrument which enables chord and bass performances to be automatically played with a predetermined rhythm simply by continuously depressing the keys of the lower keyboard in accordance with a desired chord.
An electronic organ comprises tone generators; key switch circuits associated with the upper, lower and pedal keyboards for selectively keying signals from the tone generators; tone coloring filters for converting signals selected by the key switches of the upper, lower and pedal keyboards to musical tones having predetermined tone colors; circuits for mixing and amplifying musical tones from the filters; and an electro-acoustic transducer for converting amplified musical tone signals to sounds.
One of the characteristic features of the present invention is that there is provided gating means in at least one of the two channels extending from the key switch circuits of the lower and pedal keyboards to the amplifying means, which gating means is supplied with desired rhythm pattern timing pulses from a generator thereof. Depression of the keys of a keyboard associated with the channel having the gating means causes the means to be continuously supplied with the selected signals from the tone generator. Timing pulses from the generator open the gating means at a predetermined rhythm interval, thereby producing musical tones having desired rhythm patterns from a loud-speaker.
Another characteristic feature of the present invention is that there is included means for automatically detecting the type of the chord when the keys of the lower keyboard are depressed for a chord performance and there is further provided gating means in each of the lower and pedal keyboard channels. The chord detecting means permits the gating means of the pedal keyboard channel to be continuously supplied with bass tone signals corresponding to two main notes, that is, the root and the fifth of the chord played on the lower keyboard. A chord depression on the lower keyboard continuously impresses the gating means disposed in the channel thereof with signals representing the aforesaid two main notes included in the chord. Since the pulse generator supplies both gating means with rhythm pattern timing pulses conforming with the chord and bass performances, mere continuous depression of the keys on the lower keyboard enables a chord performance and a bass performance with the root and fifth of the chord to be automatically played.
Still another characteristic feature of the present invention is that there is provided means which, upon depression of the keys on the lower keyboard for a chord performance, detects notes of the highest and lowest pitches included in the chord performance, and supplies bass tone signals corresponding to those notes to the gate circuit of the pedal keyboard channel. When the gate circuits of the lower and pedal keyboard channels are supplied with rhythm pattern timing pulses from the generator, there is automatically conducted a bass performance by the highest and lowest notes of the chord as well as a chord performance.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a block circuit diagram of an electronic musical instrument according to an embodiment of the present invention;
FIGS. 2A, 2B and 2C are musical notations for explaining the operation of the electronic musical instrument of FIG. 1;
FIG. 3 is a block circuit diagram of an electronic musical instrument according to another embodiment of the invention;
FIG. 4 is a block circuit diagram of an electronic musical instrument according to still another embodiment of the invention;
FIGS. 5A, 5B and 5C are musical notations for explaining the operation of the electronic musical instrument of FIG. 4;
FIG. 6 is a circuit diagram of the chord detector of FIG. 5;
FIG. 7 represents a base selector and gate circuit of FIG. 5;
FIG. 8 is a modification of the circuit of FIG. 7;
FIG. 9 is a chart illustrating the components of chords in the key of C;
FIG. 10 is a block circuit diagram of an electronic musical instrument according to a further embodiment of the invention; and
FIG. 11 indicates the arrangement of the priority switcher of FIG. 10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A schematic electronic organ system is included in FIG. 1 illustrating one embodiment of this invention. The system includes tone generators 1, outputs from which are branched off to an upper keyboard channel 2, lower keyboard channel 3 and pedal keyboard channel 4. The upper keyboard channel 2 comprises an upper keyboard 5 including associated key switch circuits for selectively keying signals from the tone generators 1 and tone coloring filters 8 for converting signals selected by the key switch circuits 5 to musical tone signals having proper timbres. Like the upper keyboard channel 2, the lower and pedal keyboard channels 3 and 4 respectively comprise a lower keyboard 6 and a pedal keyboard 7 including associated key switch circuits for selectively keying signals from the tone generators 1 and tone coloring filters 9 and 10 for converting signals selected by the key switch circuits 6 and 7 to musical tone signals having proper timbres. The key switch circuits of the keyboard channel are supplied with tone signals from the tone generators 1 which have frequencies corresponding to the notes to be played on the keyboard. Musical tone signals from the tone coloring filters are mixed and conducted to an amplifier. Musical tone signals thus amplified actuate a loud-speaker 12. The aforesaid electronic organ system is already known and will be fully understood without detailed description.
In an embodiment of the present invention, the lower and pedal keyboard channels 3 and 4 have gate circuits 13 and 14 positioned between the respective switch circuits 6 and 7 and the tone coloring filters 9 and 10. There is further provided a rhythm pattern pulse generator 15, which comprises a pulse generator 16 and timing pulse encoders 17 and 18. Timing pulses from the encoders 17 and 18 are supplied to the gate circuits 13 and 14 to open them in accordance with the rhythm patterns represented by the pulses. The pulse generator 16 comprises, for example, an astable multivibrator having a variable oscillation frequency and a ring counter formed of a necessary number of flip-flop circuits which are impressed with output pulses from the astable multivibrator. As is well known, there are drawn out pulses in turn from the flip-flop circuits constituting the ring counter. The timing pulse encoder may consist of a diode matrix circuit. In this case, the column lines, for example, of the matrix circuit to be supplied in turn with pulses from the pulse generator 16 have the same number as the flip-flop circuits constituting the ring counter. On the other hand, the row lines of the matrix circuit are provided in the same number as desired rhythm patterns. At the intersections defined by one row line with the column lines are connected diodes disposed in accordance with a predetermined rhythm pattern. From the row lines stored with different rhythm patterns, is selected one row line with desired rhythm pattern. The rhythm pattern pulses from the row lines are conducted to the gate circuit after being shaped by a differentiating circuit having a proper time constant. Details of such rhythm pattern pulse generator and other processes relative thereto are already clearly set forth in the U.S. Pat. Nos. 3,255,292, 3,358,068 and 3,383,452.
In the embodiment of FIG. 1, the upper keyboard plays a melody performance as usual. On the lower keyboard, there are continuously depressed a plurality of keys corresponding to notes constituting a desired chord in conjunction with the melody performance. On the pedal keyboard, there is depressed a key corresponding to, for example, the root of the chord. Accordingly, the gate circuits 13 and 14 disposed in the lower and pedal keyboard channels 3 and 4 are normally supplied with signals corresponding to the pitches of notes represented by the depressed keys. The gate circuits 13 and 14 are impressed by the rhythm pattern pulse generator 15 respectively with a sequence of pulses having a rhythm pattern conforming with a melody performance and are opened only upon the impression. From the gate circuits 13 and 14, therefore, there are intermittently drawn out signals corresponding to the rhythm pattern. Signals from the pedal keyboard channel are bass tone signals having a frequency one octave lower than that of the root of the chord.
The aforementioned matter will be more clearly understood by reference to FIGS. 2A, 2B and 2C. FIG. 2C represents chords and basses to be played on the lower and pedal keyboards respectively. As apparent from FIG. 2C, there are played on the lower keyboard four beats of the chord C in the first measure, four beats of the chord F in the second measure, four beats of the chord G in the third measure and again the chord C in the fourth measure, and there are played on the pedal keyboard notes C, F and G constituting the root of each chord at a period twice that of the notes played on the lower keyboard.
According to an embodiment of the present invention, where there are continuously depressed, for a whole note length, the keys of the lower keyboard corresponding to the notes G, C and E constituting the chord C in the first measure as shown in FIG. 2B, and the key of the pedal keyboard corresponding to the note C constituting the root of the chord C, then the gate circuits 13 and 14 are respectively supplied with the tone signals corresponding to the aforementioned notes to be gated and at the same time with sequences x and y of pulses having the rhythm patterns of FIG. 2A. Thus there are produced musical tones having the rhythm of FIG. 2C from the lower and pedal keyboard channels through a loud-speaker 12. Where there are continuously depressed for a whole note length in the second measure the keys of the lower keyboard corresponding to the notes A, C and F constituting the chord F and the key of the pedal keyboard corresponding to the note F constituting the root of the chord F, then there are sounded by the rhythm pattern pulses of FIG. 2A these musical tones having the same rhythm pattern as that of the first measure. Thus continuous depression of the keys on the lower and the pedal keyboards enables the desired chord and bass performances to be automatically played in the desired rhythm by the action of the rhythm pattern pulses and the gate circuits.
In the embodiment of FIG. 1, there is provided a gate circuit in both lower and pedal keyboard channels. Such arrangement permits the right hand to be used exclusively in operating the upper keyboard for a melody performance, and the left hand and foot to operate the lower and pedal keyboards with great ease. However, the gate circuit may be formed only in either of the lower and pedal keyboard channels. If in this case, the player engages himself mainly in the operation of, for example, the lower keyboard, he will be able easily to play the other pedal keyboard at the same time, in the channel of which there is disposed a gate circuit. Alternatively, there may be formed a gate circuit in both channels in advance, and either or both of the gate circuits may be selectively used according to the object of practice. For elevation of performance effect, the embodiment of FIG. 1 may be developed into that of FIG. 3, wherein the gate circuits 21 and 22 are normally supplied with output signals from, for example, two percussion tone generators 19 and 20 incorporated in an electronic organ and further controlled by rhythm pattern pulses from timing pulse encoders 23 and 24 specifically included in the rhythm pattern pulse generator 15, for the performance of the rhythm section of the band music. The same parts of FIG. 3 as those of FIG. 1 are denoted by the same numerals and description thereof is omitted.
If an electronic organ is so designed for simplification of its operation as to permit a bass performance to be automatically conducted in the form conforming with a chord performance on the lower keyboard simply by operation of the lower keyboard which is originally intended to play a chord performance, then there will be offered greater convenience for a beginner.
The embodiment of FIG. 4 has been developed to attain the aforementioned object. The same parts of FIG. 4 as those of FIG. 1 are denoted by the same numerals. The embodiment of FIG. 4 further includes a bass selector 25 and a chord detector 26. This bass selector 25 corresponds to the pedal key switch circuits 7 of FIG. 1. The bass selector 25 is supplied with the same bass tone signals as the pedal key switch circuits 7, so that the channel including the selector 25 is also hereinafter referred to as "the keyboard channel." The chord detector 26 is provided for detecting the type of the chord being played on the lower keyboard. Detected outputs from the chord detector 26 enable the aforesaid bass selector 25 to select those bass tone signals from the tone generator 1 which represent notes corresponding to the root and the fifth contained in the chord being played on the lower keyboard. As in the embodiment of FIG. 1, there are formed gate circuits 13 and 14 in the lower and pedal keyboard channels 3 and 4. The gate circuit 13 of the lower keyboard channel 3 is supplied for an automatic rhythmic performance of the chords with a rhythm pattern pulse or timing pulse from the timing pulse encoder 17 included in the rhythm pattern pulse generator 15. The gate circuit 14 provided in the pedal keyboard channel 4 is supplied from the timing pulse encoder 18 with two kinds y and z of rhythm pattern pulses or timing pulses for the root and the fifth selected by the bass selector 25 in order to carry out an automatic rhythmic performance of the basses.
There will now be described by reference to FIGS. 5A, 5B and 5C, the operation of the embodiment of FIG. 4. FIG. 5C illustrates a chord performance on the lower keyboard and a bass performance on the pedal keyboard which are to be played in conjunction with a melody performance on the upper keyboard. As apparent from FIG. 5C, there are to be played on the lower keyboard a chord C in the first measure, a chord F in the second measure, a chord G 7 in the third measure and again the chord C in the fourth measure. On the pedal keyboard, there are to be successively played in the first measure the root note C and the fifth note G of the chord C, in the second measure the fifth C and the root F of the chord F, in the third measure the fifth D and the root G of the chord G 7 , and in the fourth measure the root C of the chord C. In the embodiment of FIG. 4, it is only required for a chord performance to continuously depress the keys of the lower keyboard corresponding to the chord notes of each measure for the whole measure length as shown in FIG. 5B. In the meantime, the gate circuit 13 of the lower keyboard channel 3 is supplied from the timing pulse encoder 17 with a sequence x of rhythm pattern pulse for a chord performance as illustrated in FIG. 5A, causing a chord performance shown in FIG. 5C to be automatically played as in the embodiment of FIG. 1. The gate circuit 14 of the pedal keyboard channel 4 is also supplied with signals representing the root and the fifth of the respective chords and a sequence y of rhythm pattern pulse for the root and a sequence z of rhythm pattern pulse for the fifth from the timing pulse encoder 18, thereby enabling an automatic bass performance shown in FIG. 5C which would otherwise have to be effected by the actual complicated operation of the pedal keyboard by the player himself.
In the embodiment of FIG. 1, the pedal keyboard was described as playing only the root of the chord which was to be played by the lower keyboard. However, the embodiment of FIG. 4 permits a bass performance to be automatically conducted by the root and the fifth of the chord, providing a more prominent musical effect.
There will now be described by reference to FIG. 6 the chord detector of FIG. 4. The chord detector 26 consists of a matrix circuit comprising a plurality of column lines, row lines and diodes positioned at the prescribed intersections of both lines. The matrix circuit has twelve column lines L 1 to L 12 corresponding to the notes of one octave, the ends on one side of the column lines being grounded by normally open key switches S 1 to S 12 operated by the respective keys of the lower keyboard. The switches actuated by the keys corresponding to the same notes in the different octaves are respectively connected to the same common column lines included in the matrix circuit. The ends on the other side of the column lines are connected through a resistor 27 to one end of a common power source 28, the other end of which is grounded. The matrix has the same number of row lines 0 1 , 0 2 , 0 3 , . . . as the kinds of chords to be played by the lower keyboard. FIG. 6 indicates seven row lines representing chords C, F, G 7 , A m , D m , D 7 and B♭. At the prescribed intersections between the row lines denoting these chords and column lines are connected diodes in the forward direction with respect to the polarity of the power source 28 to which the column lines are connected to detect, for example, chord C, there are connected diodes D of the indicated polarity to three intersections defined by row line 0 1 with column line L 1 , connected to switch S 1 operated by the key of the lower keyboard corresponding to note C included in chord C, column line L 5 connected to switch S 5 . corresponding to note E and column line L 8 connected to switch S 8 corresponding to note G.
Referring to the operation of the aforesaid chord detector, the diodes are connected to the intersections of the row lines and column lines in the forward direction with respect to the positive source voltage, so that the potential of the detection terminal of the row line is normally kept positive. Depression of the keys of the lower keyboard corresponding to, for example, notes C, E and G causes switches S 1 , S 5 and S 8 to be closed and in consequence column lines L 1 , L 5 and L 8 to be grounded. Accordingly, the power source 28 is short-circuited with column lines L 1 , L 5 and L 8 by the resistor 27, preventing row line 0 1 connected to column lines L 1 , L 5 and L 8 by the diodes from being impressed with voltage, so that the potential of the detection terminal of row line 0 1 , that is, the voltage across the resistor 30 is reduced to zero. At this time, the potentials of the detection terminals of the other row lines are still kept positive. From the fact that the potential of the detection terminal of row line 0 1 associated with the chord C was changed from positive to zero, it is determined that the chord performed by operation of the lower keyboard was C. The detected output controls the bass selector 25. This selector 25 may be constructed as illustrated in FIG. 7. The bass tone signals, for example, of notes C and G corresponding to the root and the fifth of chord C are directly supplied from the tone generator to the transistors T 1 and T 2 without passing through the key switches operated by the pedal keyboard, and the emitter of both transistors T 1 and T 2 is grounded by the chord C detecting circuit 26c. The chord C detecting circuit is included in the above-mentioned chord detector. For simplification, three switches S 1 , S 5 and S 8 and three diodes are indicated by one switch S c and one diode D c respectively.
When chord C is not detected, namely, when the switch S c of the chord C detector is opened, the voltage of the emitters of transistors T 1 and T 2 supplied by the power source 28 is set at a higher level than the base bias voltage, thereby bringing the transistors T 1 and T 2 into an inoperative stage. Upon detection of chord C, namely, when the switch S c of the chord C detector is closed, the emitters of transistors T 1 and T 2 are disconnected from the power source 28 and grounded through the resistor 30, bringing the transistors T 1 and T 2 into an operative state. Accordingly, signals representing the root and the fifth of the chord C supplied to the base of transistors T 1 and T 2 are drawn out from the collectors and conducted to gate circuits 14A and 14B intended for the root and the fifth respectively. The emitters of transistors T 3 and T 4 constituting the gate circuits 14A and 14B are supplied with rhythm pattern pulses y and z for the root and the fifth as shown in FIG. 5A. The rhythm pattern signals consist of a sequence of negative pulses which normally have a positive potential and assume a low or zero voltage when they are pulsed. Normally, therefore, the positive potential supplied to the emitter of the transistors T 3 and T 4 is maintained at a higher level than the base bias voltage, thereby bringing the gate circuits 14A and 14B into an inoperative state. When negative rhythm patterns are introduced, the emitter potential decreases from the base potential, actuating or opening the gate circuits 14A and 14B. Thus only when there are introduced negative pulses, there are drawn out musical tone signals from the gate circuits 14A and 14B. Musical tone signals corresponding to the root and the fifth of the chord C are mixed and conducted to the tone coloring filter 10. The bass selector 25 further includes transistors T 5 and T 6 and so on which are supplied with tone signals corresponding to the roots and the fifths of other chords. The emitters of transistors T 5 and T 6 are grounded by a circuit for detecting the chord C♯. Outputs from the transistors T 1 and T 5 and so on supplied with tone signals corresponding to the roots of the chords are conducted to the common gate circuit 14A for the root, while outputs from the transistors T 2 and T 6 and so on supplied with tone signals corresponding to the fifths of the chords are impressed on the common gate circuit 14B for the fifth. The function of the bass selector 25 consists in previously supplying a pair of transistors with bass tone signals corresponding to the root and the fifth of the one chord to be detected at a time by the chord detecting circuit 26 and simultaneously controlling the paired transistors by the detected output from the chord detector.
In the embodiment of FIG. 7, the bass selector and the gate circuits are separately arranged. However, the transistors of the bass selector 25 supplied with tone signals corresponding to the root and the fifth of the chord may be made concurrently to act as a gate circuit. Such embodiment is given in FIG. 8. There is provided a diode D 8 between the emitters of the paired transistors T 1 and T 2 of FIG. 7 controlled in common by the chord C detector 26c and the chord detector 26c in the opposite direction to the base-emitter diode included in the transistors, and there is also disposed a resistor R 8 between the emitters of transistors T 1 and T 2 and the earth. Timing pulses y and z are supplied respectively to the emitters of transistors T 1 and T 2 through a diode D 9 disposed in the opposite direction to the baseemitter diode. When chord C detector 26c becomes inoperative, the emitters of transistors T 1 and T 2 are kept at a positive potential by the power source 28 so as to prevent the transistors from being jointly operated. Upon actuation of the chord C detector 26c, the emitters of the transistors are disconnected from the power source 28. Even though the transistors tend to be actuated due to their emitters being grounded through the resistor R 8 , the emitters of the transistors are still kept at a positive potential and do not become operative during the period of positive potential included in a sequence of timing pulses supplied to the emitter through the diode D 9 . During the period of negative pulses in which the potential is reduced, the emitter potential of transistor T 1 for example decreases from its base potential, so that the transistor T 1 is brought into an operative state and there are drawn output signals from the collector of transistor T 1 . It will be apparent that the transistors T 1 and T 2 are independently brought to an operative state by the respective timing pulses.
In the chord detecting circuit of FIG. 6, there were connected three diodes to the row lines so as to have each chord distinguished by the three notes included therein. It will be apparent, however, that where the chord is constitutied by four notes, the row line may be provided with four diodes. For further simplification, the detection of the chord may be effected only by two notes, that is, the root and the fifth of the chord. In this case, there are provided diodes only at the intersections defined, for example, by the raw line 0 1 with column line L 1 corresponding to the note C constituting the root of the chord C and column line L 8 corresponding to the note G constituting the fifth of the chord C. In FIG. 6, the chord detector is designed to detect chord C by the notes C, E and G. As apparent from FIG. 9, however, there are other chords C, C 6 , and C M7 each of which contains the notes C, E and G. Detection of these chords, therefore, produces common detected output. There are still other chords C, Cm, C 6 , Cm 6 , C 7 , and Cm 7 , each of which contains the notes C and G. Therefore, in the case of detecting the chords above mentioned including two common notes C and G the chord detector produces a common detected output. Since, however, there is no need for the beginner to distinguish between the aforementioned chords, detection of the chords by only two notes will not present any practical difficulties.
The embodiment of FIG. 4 enables the chord detector to distinguish the kind of chord played by the lower keyboard and also a bass performance to be conducted by bass tone signals corresponding to the root and the fifth of the chord. Consequently the arrangement becomes exceedingly complicated as shown in FIGS. 6 and 7. In fact, bass tones played by the pedal keyboard often represent the outer part tones of the chord played with the left hand on the lower keyboard, namely, the highest and the lowerst notes of the chord. Therefore, it is not always necessary to rely on the root and the fifth for a bass performance.
FIG. 10 denotes an embodiment wherein, during the chord performance by the lower keyboard, there are detected the highest and the lowest pitch notes of the chord and the performance is conducted by bass tone signals corresponding to the highest and lowest notes. In the embodiment of FIG. 10 there is used, instead of the chord detector 26 and the bass selector 25, a priority switcher 31 which is normally supplied with bass tone signals from the tone generator 1 and operated interlockingly with the lower keyboard 6, namely, contains a plurality of switches operated by the lower keyboard, thereby preferentially selecting the highest and the lowest notes of the chord played on the lower keyboard. The other parts of FIG. 10 are of the same arrangement as in FIG. 4.
The priority switcher 31 comprises, as shown in FIG. 11, first and second groups 32 and 33 constructed by first and second switches respectively which are operated by the same key of the lower keyboard. Each switch constituting the first switch group 32 has a movable contact 35 connected with a normally closed fixed contact of a switch positioned in the adjacent lower tone section, a normally closed contact 36 and a normally open fixed contact 37 connected with the tone generator, and each switch constituting the second switch group 33 has a normally closed fixed contact 38, a movable contact 39 connected with a normally closed fixed contact of a switch positioned in an adjacent higher note section and a normally open fixed switch 40 connected with the tone generator along with the normally open contact 37 of the switch actuated by the same key of the lower keyboard. The movable contact 35 of the switch, that is, the switch actuated by the key corresponding to the note C in the drawing, positioned in the lowest tone section of first switch group 32 for selecting the lowest bass tone signal and the movable contact 39 of the switch, that is, the switch actuated by the key corresponding to the note B, positioned in the highest section of the second switch group 33 for selecting the highest bass tone signal are connected to the gate circuit 14 shown in FIG. 10, as the bass tone input signals.
There will now be described the operation of the switcher of FIG. 11. Depression of the keys of the lower keyboard corresponding to the notes C, E and G to play for example, chord C actuates six corresponding switches. Namely, the movable contact of each switch connected to a normally closed fixed contact is switched to a corresponding normally open fixed contact connected to the tone generator. While the movable contact 35 of each of those of the first group switches 32 which are associated with the notes C, E and G is switched from a corresponding normally closed contact 36 to a corresponding normally open contact 37, the movable contact 35 of the switch associated with the note C is switched to a corresponding normally open fixed contact 37 connected to the tone generator, so that the gate circuit 14 is supplied with a tone signal representing the pitch of the note C. On the other hand, among the switches of the second group 33, the movable contact 39 of each of those associated with the notes C, E and G is switched from a corresponding normally closed fixed contact 38 to a corresponding normally open fixed contact 40. In this case, the movable contact 39 of that of these three switches which is associated with the highest note, namely, the note G is switched from the corresponding normally closed fixed contact 38 of a switch representing a note next higher than G to a corresponding normally open fixed contact 40 connected to the tone generator. Thus a tone signal having the pitch of the note G passes through the intermediate switches and is finally drawn out from the movable contact 39 of a switch representing the highest note B and supplied to the gate circuit 14. In the performance of chord C by the lower keyboard, tone signals having the pitches of the lowest note C and the highest note G included in the chord C are drawn out and supplied to the gate circuit 14. This gate circuit 14 supplied with tone signals representing the highest and lowest notes may be constructed in the same manner as the gate circuits 14A and 14B for the root and the fifth illustrated in FIG. 7.
Referring to FIG. 11, each group of switches constituting the switcher consists of 12 switches so as to match twelve notes included in one octave. Since, however, the lower keyboard includes more than 12 keys, the group practically has the same number of switches as the keys. The switches associated with the same note are arranged parallel. Namely, the movable contacts, normally closed fixed contacts and normally open fixed contacts of these switches are respectively connected to each other.
According to the foregoing description, the base tone signal denoting the lowest note C of chord C represents its root and the bass tone signal indicating the highest note G of the chord C represents its fifth. Depending on the inversions of chord played, however, the bass tone signals do not always bear such relationship. Where it is desired to take out a root and a fifth as the lowest and highest notes respectively, it is only required to operate the lower keyboard in such a manner that the lowest and highest notes represent the root and the fifth of a chord, i.e. the chord in the root position.
Further, the gate circuit 14 supplied with signals of the lowest and the highest notes selected by the priority switcher 31 of FIG. 8 is impressed, as in the embodiment of FIG. 4, with rhythm pattern pulses x and y from the timing pulse encoder 18 of the rhythm pattern pulse generator 15, thus enabling a rhythm performance by bass tones to be automatically conducted without operating the pedal keyboard.
It will be apparent that if there are incorporated all the aforementioned embodiments of the present invention in a single electronic organ in such a manner that the function or feature of each embodiment can be freely selected by a beginner, then there will be the advantage of permitting him to conduct various forms of practice.