US3707594A - Automatic rhythm sound producing device adapted for use with keyboard musical instruments - Google Patents

Abstract

An automatic rhythm sound producing device built in a keyboard musical instrument capable of playing ordinary tones of the melody, chord or bass, or combinations thereof upon selective depression of a plurality of keys arranged in the order of musical notes. The device includes a combination pulse generator which comprises a clock pulse generator followed by a frequency dividing counter chain to generate combination pulses, and having a resetting arrangement. The outputs from the combination pulse generator are supplied to a timing pulse encoder so as to cause outputs of the various stages of the counter chain to appear on the output lines of the encoder as a train of selected timing pulses which represent desired rhythm patterns. The outputs from the encoder are supplied to individual rhythm sound generators to produce rhythm sounds according to the selected rhythm patterns for an automatic rhythm performance. A trigger generator is provided to detect a depression of a key and upon detection to start the normally reset counter chain, thereby initiating the automatic rhythm performance.

Description

United States Patent Ichikawa 1 Dec. 26, 1972 54 AUTOMATIC RHYTHM OU 3,291,910 12/1966 Nicklas et a1 ..307/220 X I 1 PRODUCING DEVICE ADAPTED FOR 3,490,327 1/1970 Volpe ..331/51 x 2,931,922 4/1960 Tubinis ..307/223 U WITH KEYBOARD MUSICAL 3,546,355 12/1970 Maynard ..s4 1.03 INSTRUMENTS 3,567,838 3 1971 Tennes ..s4 1.03 x 3,247,307 4/1966 Campbell ..84ll.24 X [721 XII/"Sm lchlkwa Hamak'Fa, Japan 3,482,027 12/1969 Okamoto et a1 ..s4 1.03 [73] Assigneez Nippon Gakki Seizo Kabushiki 3,549,774 12/1970 Hunger ..84/l.03 Kaisha, Hamamatou-shi, Shizuokaken Japan Primary Exammer-Rwhard B. W11k1nson Assistant Examiner-U. Weldon [221 Flledl March 1971 Attarney-Flynn & Frishauf 21 A 1. N 121,387 I 1 pp 57 ABSTRACT An automatic rhythm sound producing device built in [30] Foreign Application Priority Data a keyboard musical instrument capable of playing or- 2 dinary tones of the melody, chord or bass, or com- March 10, 1970 Japan "25/1508 binations thereof p Selective depression of a p March 10,1970 Japan 5/ 911 y of y arranged in the Order of musical notes- The device includes a combination pulse generator [52] which comprises a clock pulse generator followed by a 0f 00 frequency dividing counter chain to generate com- [51] f i DIG bination pulses, and having a resetting arrangement. [58] d 0 can l 5 3 5 The outputs from the combination pulse generator are 30 2 supplied to a timing pulse encoder so as to cause outputs of the various stages of the counter chain to appear on the output lines of the encoder as a train of [56] Rderences d selected timing pulses which represent desired rhythm UMTED A E TENTS patterns. The outputs from the encoder are supplied to individual rhythm sound generators to produce 3,383,452 5/1968 Parkketal. rhythm Sounds according to the selected rhythm Pat 2 l e m zlll IIIIIIIIIIIIIIIII x terns for an automatic rhythm performance. A trigger 358589l 6/1971 Schwartz generator is provided to detect a depression of a key 3473633 H1969 jf' and upon detection to start the normally reset counter 3:548:066 12 1970 Freeman... ..84/1.24X chain, thereby initiating the automatic rhythm P 3,358,068 12/1967 Campbell ..84/l.03 X formance.

7 Claims, 6 Drawing Figures 3 6 l F 111111111 -1 32 34 311 312 3g?) 3In 3S5 VRI A S TONE TONE COLORING g 1 KEYER g AMPLIFIER GENERATOR v I FILTER 1 I L j J COMBINATION TIMING PULSE RHYTHM SOUND PULSE GENERATOR ENCODER GENERATORS S I f t 39 40 3 8 41 VR2 TRIGGER GENERATOR 3? PATENTEDHECZG I972 3.707.594

SHEEI 5 0F 5 F l G. 5 "r2 I712 i n S S TONE CHORD CHORD GENERATOR DETECTOR MEMORYk SW'TCHER BASS MEMORY SW|TCHER 7 RHYTHM PATTERN GENERATOR F l G 6 S 1 f f T CLOCK PULSE GENERATOR FF FFZ FF3 FF4 1 AUTOMATIC RHYTHM SOUND PRODUCING DEVICE ADAPTED FOR USE WITH KEYBOARD MUSICAL INSTRUMENTS BACKGROUND or THE INVENTION ment, for example, an electronic organ, there has recently been morefavorably accepted a type in which there is incorporated an automatic rhythm sound producing device having a rhythm section for playing the percussion sounds of the claves, cymbals, tom tom, cowbell, or bass drum or the tones of the melody, chord or bass or combinations thereof in exact timing with a rhythm pattern selected from various rhythm tempos or patterns such as the march, rumba, tango, samba, waltz and bossa nova.

FIG. 1 is a schematic circuit diagram of a conventional keyboard electronic musical instrument in which there is incorporated the aforementioned type of automatic rhythm sound producing device. The main device of the musical instrument consists of an organ section 16 comprising keyboards 12 having a plurality of keys 11,, 11 11, arranged in the order of musical notes; keyers 13 associated with the keys 11, of the keyboards 12 and provided with a plurality of keying switches operated upon selective depression of the corresponding keys; tone generators 14 designed to enable to generate tone signals having pitches preset for the respective keys and, upon selective operation of the keying switches, produce the corresponding tone signals therefrom; and tone coloring filters 15 so designed as to form musical sounds having desired tone colors from the tone signals, On the other hand, the automatic rhythm sound producing device consists of a rhythm section 25 comprising a combination pulse generator 22 formed of a clock pulse generator followed by a frequency dividing counter chain for selecting a desired rhythm pattern from among thevarious types of rhythm patterns and actuated by a normally open switch 21 manually closed at the start of a rhythm performance; a timing pulse encoder 23 consisting of a proper logic circuit including diodes in matrix arrangement so as to selectively form a train of timing pulses corresponding to adesired rhythm pattern from combination pulses supplied from the generator 22; and rhythm sound generators 24 for generating rhythm sound signals being triggered by the timing pulses. The resultant output signals from the sections 16 and 25 are conducted'through separate volume controllers VR, and VR, respectively and one common amplifier A which may be provided separately) to be reproduced from a loud-speaker S (which may be provided separately).

However, where it is desired to play both the tones of the melody, chord 'or bass or combinations thereof fromthe section 16 and the rhythm soundsfrom the section 25, the conventional instrument having an automatic rhythm sound producing device built therein in the aforementioned manner has the drawbacks that there is not only required a troublesome process of operating the start switch 21 for rhythm sound performance in addition to selective depression of a desired key on the keyboards 12 for musical scale tone performance, but also there are presented appreciable difficulties in exactly timing the initiation of rhythm sound performance with that of musical tone performance.

Further, the prior art instrument generally so designed as to play as many varieties of performance as possible by full working of both hands and feet of a player has a disadvantage that when additionally equipped with the afore-said rhythm section 25, then the payer is obstructed in producing such varieties of performance due to the required operation of the start switch 21.

It is, therefore, the object of the present invention to provide a novel type of automatic rhythm sound producing device adapted for use with a keyboard electronic musical instrument enabling the automatically synchronous start of the rhythm sounds with the ordinary melodytones or accompaniment sounds, thereby always exactly timing the performance of rhythm sounds from the rhythm section with that of musical tones from the organ section and effecting ,performance in a far greater variety.

SUMMARYOF THE INVENTION According to an aspect of this invention, there is provided an-automatic rhythm sound producing device incorporated in a keyboard electronic musical instrument for playing the ordinary tones of the melody, chord or bass or combinations thereof upon selective depression of a plurality of keys arranged in the order of musical notes, which device comprises a combination pulse generator formed of a clock pulse generator followed by a frequency dividing counter chain to generate combination pulses and having a resetting arrangement. The outputs at various counter stages are supplied to a timing pulse encoder to produce a train of selected timing pulses representing desired rhythm patterns, and outputs from the encoder are supplied to individual rhythm sound generators, to produce rhythm sounds according to the selected rhythm patterns for an automatic rhythm performance. A trigger generator is providied to detect a depression of thekey and upon detection to start the normally reset counter chain thereby initiating the automatic rhythm performance.

Further, this invention provides an automatic rhythm sound producing device adapted for use with a keyboard electronic musical instrument wherein there are provided normally open switches for each of several key stages, for example, upper, lower and pedal keyboards and those used in common to all the key stages, and all key operation mechanisms are coupled with the combination pulse generator through the switches, thereby enabling desired rhythm sounds to be played either at the start of performance or at any desired time during performance upon selective depression of the keys of each or all key stages.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic circuit diagram of a prior art automatic rhythm sound producing device used with a keyboard electronic musical instrument;

FIG. 2 is a schematic circuit diagram of a keyboard electronic musical instrument provided with an automatic rhythm sound producing device according to an embodiment of this invention;

, the trigger generator and combination pulse generator of-FIG. 2;

FIG. 4 is a schematic circuit arrangement of an automatic rhythm sound producing device according to 'another embodiment of the .invention adapted for use with a keyboard electronic musical instrument;

. FIG. 5 isa schematic circuit arrangement of an automatic rhythm sound producing device according to still another embodiment of the invention adapted for use with a keyboard electronic musical instrument; and

FIG. 6 is an another schematic circuit arrangement of the mainpart of connection between the keyboard and rhythm pattern generator according to the invention. DESCRIPTION or THE PREFERRED EMBODIMENTS FIG. '2 is a schematic circuit diagram of a keyboard electronicmusical instrument provided with an automatic rhythm'sound producing device according to an embodiment of this invention. The organ section 36 of the instrument comprises several keyboards 32, forexample, upper, lower and pedal keyboardsrhaving a plu-' 4. ple,a diode D. The emitter of the transistor TR, is directly grounded, whereas those'of .the remaining I transistors TR, to TR, are grounded through a normally open switch 54 closedby a player only when there are to be played rhythm sounds from the section 37. On the other hand, the combination pulse generator 39 comprises a clock pulse generator 39a formed of an astable vibrator having, for example, two transistors TR and TR and which generates a clock pulse trainwhich is a multiple of the basic rhythm frequency of the device; and a binary counter chain 39b formed of a pluralityof flip-flop circuits FF,, FF FF, and FF 4 of FIG. 3 (where there is shown in detailonly one ofthe' circuits, the others being indicated in blocks) cascadeconnected in turn to the clock pulse generator 39a,each of the flipflopcircuits including two transistorsTR and TR In this case, theemitters of the two transistorsTR and TR constituting the clock pulse generator 39a and the emitters of the corresponding ones included in each group of the paired TR and TR of the cascade connected flip-flop circuits constituting the binary counter chain 39b are directly grounded,whereas'the emitters tone signals therefrom; and tone coloring filters for properly adjusting the colors of tone signals generated so as to form the ordinary'musical tones of the melody, chord or bass or combinations thereof. In addition to the above-mentioned organ section 36, the instrument includes'a rhythm section 37 enabling rhythm sounds such as'the desired percussion e.g. cymbals,'maracas,

' drums, etc. sounds and the ordinary tones of the chord or bass sounds or combinations thereof to be played in exact timing with various tempos, for example, the march, tango, samba, bossa nova and waltz. In this c ase,'the present invention is so designed as to enable both musical tones from the organ section 36 'and rhythm sounds from the rhythm section 37 to be played upon selective depression of the keys 31, to 31,, on the keyboards 32 using, as described above, output signals from the filter 35 or keyer 33. Namely, the present invention includes a trigger generator 38 which receives outputs from the filter 35 or keyer 33 to energize a combination pulse generator 39 as later described. FIG; 3 isa concrete-circuit arrangement-of the generators 38 and 39. The triggergenerator-38 comprises an amplifier section 38a having three cascade connected transistors TR,, TR, and TR to amplify tone signal outputs from the filter 35 or keyer 33; a wave shaper 38b consistingof a clipper 51 having two transistors TR, and TR, cascade connected to the amplifier section 38a and a differentiation circuit 52 having a capacitor C and a resistor R connected to the output terminal of the clipper 51; and a bistable multivibrator 38c having two transistors TR, and TR, so arranged that the base of either of them is supplied with rectified signals obtained by passing output differentiation signals from the shaper 38b through a rectifier 53 using, for examresetting arrangement) the collector of one'transisto TR, of the bistable multivibrator 38C. I

Where, in the afore'said circuit arrangement, there are not supplied the aforementioned output signals from the filter 35 or keyer 33 to the amplifier section 38a with the switch 54 closed,'tha t is, where there is not depressed any of the keys 31, to 31,, on the keyboards 32, the other transistor TR, of the bistable mulitivibrator 38c becomes conductive, while the one transistor TR, remains nonconductive. For thepurpose of the present invention, the bistable multivibrator 38c is so designed in advance as to reverse the above-mentioned condition only when it is supplied with output signals from the filter 35 or keyer 33, that is, to cause the other transistor TR, to become inoperative and the one transistor TR, to be fired. I Where the aforesaid circuit arrangement is in a normal condition where there is not depressed any of the keys 31, to 31,, on the keyboards 32, the transistor TR, is conductive and the transistor TR thereof remains nonconductive. Accordingly, the flip-flop circuits FF, to FF, constituting each two halves designed in the same way and the binary counter chain 39b remain deenergized. Upon selective depression of any of the keys 31, to 31,,, however, the binary multivibrator 38c presents a reversed condition, that is, where the transistor TR, becomes nonconductive and the transistor TR, is energized. As a result, the emitters of the transistors constituting each set halves of the flipflop circuits included in the binary counter chain 39b are grounded through the collector of the short-circuited transistor TR, to render the flip-flop circuits energized. Thus the condition of the flip-flop circuits FF, to FF, is reversed to cause combination pulses consisting of binary outputs obtained by successive downward frequency divisionof clock pulses from the generator 39a to bedrawn out of the output terminals 1-No. 1, l-No.i2, l-No. 3' and l-No. 4 on the set halves of the flip-flop circuits FF, to FF,

Referring again to FIG. 2 a timing pulse encoder or rhythm pattern generator 40 consists of a logic circuit halves of the flip-flop circuits are supplied to the cor-,

responding input terminals in a preset combination by the player, then there is produced from the predetermined output terminals a train of timing pulses or rhythm pattern pulses exactly timed with the rhythm tempos selected from among those representing, for example, the rumba, march, tango, samba, waltz and bossa nova. The train of timing pulses thus selectively obtained from the encoder 40 is supplied to a plurality of rhythm sound generators 41 so arranged as to selectively generate the aforesaid varieties of percussion sounds so as to selectivelyexcite the predetermined one of the rhythm sound generators 41 preset by the player. Thus depression of any -of the keys on the keyboards 32 causes the desired tones of the melody, chord or bass or combination thereof from the organ section 36 with the well-timed start of the rhythm sounds from the rhythm section 37.

The automatic rhythm sound producing device arranged as described above according to the present invention for usewith a keyboard electronic musical instrument not only enables the performance of musical tones from the section 36 to be exactly timed with that of rhythm sounds from the section 37, but also the player to be free from the necessity of operating the start switch for the rhythm section as has been the case with the prior art device and consequently allowing him to carry out performance in as many varieties as possible by fully working his hands and feet. v

It will be noted that the concrete circuit arrangement associated with the combination pulse generator 39, timing pulse encoder 40 and rhythm sound generators 41 of FIG. '2 are shown in detail in FIG. 1 and the description thereof set forth in Automatic Rhythm Device invented by Richard H. Campbell, Jr., US. Pat. No. 3,358,068 (Ser. No. 378,365).

Referring to FIG. 3, a variable resistor VR included in the clock pulse generator 39a is'intended properly to regulate the repetitive period of clock pulses produced thereby. If, in FIG. 3, there is provided a switch 55 shown in dotted lines between the vacant contact 54s of the switch 54 and the collector of the one transistor TR of the bistable multivibrator 380 connected in common to the emitters of the transistors constituting the each set halves of the flip-flop circuits FF, to FF,, then it will be possible to start and stop a rhythm performance manually by a player as in the prior art device, by closing the switch 55 with the switch 54 being turned on the contact 54s.

FIG. 4 is a schematic circuit diagram of an automatic rhythm sound producing device according to another embodiment of this invention adapted for use with a keyboard electronic musical instrument. Where the instrument is provided with several keyboards arranged,

- for example, in three stages, that is, upper, lower and pedal keyboards 61, 62 and 63 the key switches 61, to 61,, 62, to 62,, and 63, to 63,, fitted to the keyboards 61, 62 and 63 respectively are jointly connected at one end to be grounded and at the other end to the base of the other transistor TR of a bistable multivibrator 381a having the samearrangement as that of FIG. 3 through separate rhythm start selector switches 64, 65 and 66 for the three respective keyboards 61, 62 and 63 and a common rhythm start selector switch 67 to all of them. The same parts of FIG. 4 as those of FIG, 3 are denoted by the same numerals and description thereof is omitted. The automatic rhythm sound producing device of FIG. 4 arranged as described above enables desired rhythm sounds not only to be automatically obtained as in the preceding embodiment but also to be started selectively in response to the selected keyboard during performance upon depression of those keys corresponding to the selectively clo'sed ones of the selector switches 64 to 67. For example, with the switch 66 along closed and the remaining switches 64, 65 and 67 left open, when the first measure of a tone is played by selectively depressing the keys 61, to 61,, and62, to 62, on the upper'and lower keyboards 61 and 62 with both hands of a player and thereafter at the start of the second measure there are selectively depressed the keys 63, to 63,, on the pedal keyboard 63 with the players feet, then it will be possible to start an automatic rhythm performance at the beginning of the second measure, being triggered by the pedal performance.

Although not shown in FIG. 2, that embodiment should preferably include in the organ section such selector switches 64 through 67 as shown in FIG. 4 before connecting to the trigger generator 38.

FIG. 5 is a schematic block circuit diagram of an automatic rhythm sound producing device according to still another embodiment of this invention adapted for use with a keyboard electronic musical instrument. The embodiment of FIG. 5 enables the ordinary tones of the melody and those of the chord or those ofv the bass adapted for the chord or combinations thereof to be played upon selective depression of several of the keys 71, to 71, arranged on keyboards 72 in the order of musical notes in exact timing with a desired rhythm pattern selected from among a plurality of rhythm tempos or rhythm patterns. The tones of a desired chord consisting of a combination of several tone signals of the prescribed pitches obtained from a tone generator 73 upon selective depression of several keys on the keyboard 72 are conducted to a chord detector 74;

This chord detector 74 is formed of, for example, a matrix circuit having a plurality of input terminals energized upon selective depression of the keys 71, to 71, and is so designed as to detect the kind of chord thus supplied as well as to draw out the base tones adapted for the detected chord from the tone generator 73.

The tones of the chord and bass thus detected are temporarily memorized in the corresponding chord memory 75 and bass memory 76. A rhythm pattern generator 77 has substantially the same arrangement as the aforementioned timing pulse encoder including the bistable multivibrator 38c and produces a desired rhythm pattern preset by the player upon selective depression of the keys 71 to 71,. The rhythm pattern generator 77 regulates the actuation of switches 78 and 79 cascade connected to the chord and bass memories 75 and 76 respectively according to the generated timing of an output rhythm pattern from the generator 77. The automatic rhythm sound producing device of FIG. 5 having the aforesaid arrangement generates the tones bass adapted therefor or combinations thereof exactly timed-with the rhythm pattern all at the same time.

FIG. 6 illustrates a concrete circuit arrangement of the other. section for triggering the binary counter chainupon selective depression of the keys without using a start switch for a rhythm performance as is the case with the conventional device. According to the embodiment of FIG. 6, the aforementioned bistable multivibrator 38c is substituted by, for example,,a field effect transistor. TR to perform an'equivalent function to that of the. multivibrator 38c. Either of the electrodes open key switches82 to. 82,, selectively'closed upon selective depression of the keys..The other terminal of each of the switches-82 to 82,, is grounded through a resistor R and connected through a diode 83, the diode being connected in the forward direction forthe current from DC supply source 81, and resistor R the diode 83 and the resistor R being connected in series, to a non-grounded side of a grounded capacitor C,, which in turn is connected to thegate electrode of the transistor TR whose source electrode is grounded and whose drain electrode is connected to a+ l3 supply source through aload resistor RL. The non-grounded side of the capacitorC, is coupled to ground through a normally open switch 84. According to the circuit of the aforementioned arrangement,'where one of the keys is selectively depressed with the switch 84 left open and the corresponding one of the switches 82, to 82,, is closed, then a D.C. current'from the DC supply source81 is charged into the capacitor-C through the forward biased diode 83. The charged voltage is supplied to the gate electrode of the transistor TR to bring it from a non-conducting to a conducting state. As a result, the voltage of the drain electrode of the transistor TR is reduced substantially to a ground level, performing an essentially equivalent action to that of the aforementioned bistable multivibrator 380. Even after thedepressed key is released to open the corresponding key switch, the charge in the capacitor C is kept as it has been, being prevented from discharging by the now backward biased diode 83 and infinitely large impedance of the gate electrode of the transistor TR and as a result the automatic rhythm performance is kept on.

When the switch 84 is closed, the voltage supplied to the capacitor C, is rapidly discharged therethrough to stop the automatic rhythm performance.

What I claim is: 1 v

1. automatic rhythm sound producing device adapted for use with a keyboard musical instrument which includes a first playing section having-a plurality; ofkeys arranged in the order of musical notes'for playing tones of a melody and those of an accompania frequency dividing counter chain including-a plurality of counter stages and coupled with the clock pulse generator for counting down to submultiples of the frequency of signals generated from said clock pulse generator and including a resetting means for maintaining said counter chain normally inoperative; i r i a timing pulse encoder connected tothe stages'of said counter chain for producing a plurality of rhythm pattern signals each being comprised of a preset different combination of output signals from saidclock generator; 1 a plurality of rhythm sound generators supplied with said respective rhythm pattern signals for producing a preset rhythm'sound corresponding to a rhythm pattern selected from the output rhythm pattern signals of said encoder; and circuit means coupled to said first playing section to generate a trigger pulse upon detection of the depression of a key in the keyboard of said separate first playing section, and connected to said counter chain through the said resetting means to initiate the operation ofsaid counter chain responsive to said detection of the depression of a key in said first playing section, thereby automatically initiating generation of rhythm sounds.

2. The automatic rhythm sound producing device according to claim'l wherein said circuit means for triggering said counter chain includes a bistablemultivibrator having two active circuit elements, means coupling a predetermined tone signal produced upon selective depression of the keys to the input terminal of one of said elements to bring it to a nonconductive state and to bring the other element to a conductive state, and means coupling the outputterminal of said other element with each stage of said counter chain to enable said counter chain.

3. The automatic rhythm sound producing device'according to claim 1 wherein saidcircuit means for trig- I gering said counter chain comprises a DC power supply with one electrode thereof grounded; a plurality of key switches connected to the other electrode of said DC power supply for generating signals upon selective depression of the corresponding keys; a rectifier for rectifying said generated signals; a capacitor for receiving the rectified signal and being charged responsive thereto; and an active circuit element having at least three electrodes with a first electrode coupled to said capacitor for supplying a signal corresponding to said charged signal, with a second electrode coupled to each stage of said counter chain to'enable said counter chain through said element only upon selective depression of the keys with a third electrode coupled to the said DC power supply. I

4. The automatic rhythm sound producing device ac-' cording to claim 1 including a plurality of manual switches and wherein said keys are arranged on several keyboards, the ends on one side of the keys on each keyboard being jointly grounded, and the ends on the other side of the keys on all the keyboards being jointly coupled 'with said circuit means for triggering said binary counter chain through corresponding manual switches.

comprises an astable multivibrator.

7. The automatic rhythm sound producing device according to claim 1 wherein said counter chain comprises a plurality of flip-flop circuits connected in cascade, the first stage of which is coupled with said clock pulse generator.

Claims (7)

1. An automatic rhythm sound producing device adapted for use with a keyboard musical instrument which includes a first playing section having-a plurality of keys arranged in the order of musical notes for playing tones of a melody and those of an accompaniment upon selective depression of said keys, said first playing section being separate from said automatic rhythm sound producing device, said automatic rhythm sound producing device comprising: a clock pulse generator for generating a repetitive frequency signal corresponding to a multiple of the basic rhythm frequency; a frequency dividing counter chain including a plurality of counter stages and coupled with the clock pulse generator for counting down to submultiples of the frequency of signals generated from said clock pulse generator and including a resetting means for maintaining said counter chain normally inoperative; a timing pulse encoder connected to the stages of said counter chain for producing a plurality of rhythm pattern signals each being comprised of a preset different combination of output signals from said clock generator; a plurality of rhythm sound generators supplied with said respective rhythm pattern signals for producing a preset rhythm sound corresponding to a rhythm pattern selected from the output rhythm pattern signals of said encoder; and circuit means coupled to said first playing section to generate a trigger pulse upon detection of the depression of a key in the keyboard of said separate first playing section, and connected to said counter chain through the said resetting means to initiate the operation of said counter chain responsive to said detection of the depression of a key in said first playing section, thereby automatically initiating generation of rhythm sounds.

2. The automatic rhythm sound producing device according to claim 1 wherein said circuit means for triggering said counter chain includes a bistable multivibrator having two active circuit elements, means coupling a predetermined tone signal producEd upon selective depression of the keys to the input terminal of one of said elements to bring it to a nonconductive state and to bring the other element to a conductive state, and means coupling the output terminal of said other element with each stage of said counter chain to enable said counter chain.

3. The automatic rhythm sound producing device according to claim 1 wherein said circuit means for triggering said counter chain comprises a DC power supply with one electrode thereof grounded; a plurality of key switches connected to the other electrode of said DC power supply for generating signals upon selective depression of the corresponding keys; a rectifier for rectifying said generated signals; a capacitor for receiving the rectified signal and being charged responsive thereto; and an active circuit element having at least three electrodes with a first electrode coupled to said capacitor for supplying a signal corresponding to said charged signal, with a second electrode coupled to each stage of said counter chain to enable said counter chain through said element only upon selective depression of the keys with a third electrode coupled to the said DC power supply.

4. The automatic rhythm sound producing device according to claim 1 including a plurality of manual switches and wherein said keys are arranged on several keyboards, the ends on one side of the keys on each keyboard being jointly grounded, and the ends on the other side of the keys on all the keyboards being jointly coupled with said circuit means for triggering said binary counter chain through corresponding manual switches.

5. The automatic rhythm sound producing device according to claim 1 wherein said circuit means to generate a trigger pulse further includes selector switches for selectively detecting depressions of keys in different keyboards.

6. The automatic rhythm sound producing device according to claim 1 wherein said clock pulse generator comprises an astable multivibrator.

7. The automatic rhythm sound producing device according to claim 1 wherein said counter chain comprises a plurality of flip-flop circuits connected in cascade, the first stage of which is coupled with said clock pulse generator.

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