Nakada, Akira (Hamamatsu, JA)
Uchiyama, Yasuji (Hamakita, JA)
Hirano, Katsuhiko (Hamakita, JA)

05/239178

10/02/1973

03/29/1972

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Nippon Gakki Seizo Kabushiki Kaisha (Shizuoka-ken, JA)

84/713

984/351, 84/484

G10H1/40; G01H1/00

84/1.01,1.03,1.17,1.24,DIG.22

3358068	Automatic rhythm device	December 1967	Campbell
3585891	AN ELECTRONIC RHYTHM GENERATOR PARTICULARLY SUITABLE FOR INTEGRATED CIRCUITRY	June 1971	Schwartz et al.
3629480	RHYTHMIC ACCOMPANIMENT SYSTEM EMPLOYING RANDOMNESS IN RHYTHM GENERATION	December 1971	Harris

Wilkinson, Richard B.

Witkowski, Stanley J.

What we claim is

1. In an automatic rhythm playing apparatus having memory means in which information is stored, first address means for providing cyclically changing address signals to said memory means, second address means for providing constant address signals corresponding to selected information stored in said memory means, said memory means producing output signals corresponding to the selected information in response to said cyclically changing and constant address signals, and gating means connected to said first address means for producing percussion instrument sound signals by application thereto of the output signals of said memory means to obtain a rhythm sound signal consisting of a plurality of percussion instrument sound signals.

2. An automatic rhythm playing apparatus as defined in claim 1 in which said first address means comprise a clock pulse oscillator, a dynamic counter having a plurality of stages for successively counting clock pulses and a decoder for decoding the outputs of each stage of said dynamic counter into address signals which circulate in accordance with repetition of counting of said counter.

3. An automatic rhythm playing apparatus as defined in claim 1 in which said second address means comprise a plurality of rhythm selection switches, a rhythm selection signal generating circuit for generating a rhythm selection signal by closing of a desired rhythm selection switch and a decoder for decoding the output of said rhythm selection signal generating circuit into an address signal which is peculiar to the selected rhythm.

4. An automatic rhythm playing apparatus as defined in claim 1 in which said memory means consist of a read only memory.

5. An automatic rhythm playing apparatus as defined in claim 1 in which said means for obtaining a rhythm sound signal comprise a gate circuit connected to the output of said memory means, a gate signal waveshaping circuit for supplying a gate pulse having a sharp waveform synchronized with the clock pulse to said gate circuit and a percussion instrument sound signal generating circuit having oscillators for each percussion instrument sound respectively driven by the output of said gate circuit.

6. An automatic rhythm playing apparatus as defined in claim 2 which further comprises a 1/4 frequency divider consisting of first and second flip-flops provided between the output of said clock pulse oscillator and the input of said dynamic counter and a switch for feeding back the output of said second flip-flop to the input of said first flip-flop whereby a percussion instrument sound signal for a triplet is obtained at a specific output terminal of said memory means by closing of said switch.

7. An automatic rhythm playing apparatus as defined in claim 6 which further comprises at least two rhythm selection circuits, at least two rhythm units respectively provided in correspondence to said rhythm selection circuits for receiving a rhythm selection signal from the corresponding rhythm selection circuit and producing a plurality of percussion instrument sound generating signals having pulses corresponding to the notes of each percussion instrument sound of the selected rhythm, and a percussion instrument sound signal generating circuit having oscillators for each percussion instrument sound driven by said percussion instrument sound generating signal.

8. An automatic rhythm playing apparatus as defined in claim 7 in which each rhythm unit comprises a dynamic counter having a plurality of stages for counting pulses obtained by frequency dividing the clock pulses, a first decoder for decoding the outputs of each stage of said dynamic counter into a first address signal, a second decoder for decoding the rhythm selection signal into a second address signal, a memory which digitally stores notes of a plurality of rhythms for each percussion instrument sound and from which a signal having a note arrangement of the selected rhythm for each percussion instrument sound is read out by said first and second address signals, and a gate circuit for gating the read out output of said memory thereby to obtain a percussion instrument sound generating signal.

9. An automatic rhythm playing apparatus comprising memory means storing a plurality of rhythm patterns, address means for providing cyclically changing address signals to said memory means to read out said plurality of rhythm pattern signals from said memory means, rhythm pattern selection circuit means for selecting the rhythm pattern signals corresponding to the kind of rhythm selected, means for supplying a constant address signal corresponding to the selected rhythm to said rhythm pattern selection circuit means and gating means connected to the address means for producing percussion instrument sound signals by application thereto of the outputs of said rhythm pattern selection circuit means to obtain a rhythm sound signal consisting of a plurality of percussion instrument sound signals.

10. An automatic rhythm playing apparatus as defined in claim 9 in which said address means comprise a clock pulse oscillator, a dynamic counter having a plurality of stages for successively counting clock pulses and a decoder for decoding the outputs of each stage of said dynamic counter into address signals which cyclically change in accordance with repetition of counting of said counter.

11. An automatic rhythm playing apparatus as defined in claim 9 in which said means for supplying a constant address signal comprise a plurality of rhythm selection switches, a rhythm selection signal generating circuit for generating a rhythm selection signal by closing of a desired rhythm selection switch and a decoder for decoding the output of said rhythm selection signal generating circuit into an address signal which is peculiar to the selected rhythm.

12. An automatic rhythm playing apparatus as defined in claim 9 in which said memory means and said rhythm selection circuit means respectively consist of a read only memory.

13. An automatic rhythm playing apparatus as defined in claim 9 which further comprises a lamp lighting means for lighting a lamp at each predetermined note of a specific rhythm pattern in response to a specific output of said rhythm pattern selection circuit means.

14. An automatic rhythm playing apparatus as defined in claim 13 in which said means for obtaining a rhythm sound signal comprise a gate circuit connected to the output of said rhythm pattern selection circuit means, a gate signal waveshaping circuit for supplying a sharp gate pulse synchronized with the clock pulse to said gate circuit, a start switch for supplying voltage to said gate circuit by closing thereof and a percussion instrument sound signal generating circuit having percussion instrument sound oscillators respectively driven by the output pulse of said gate circuit.

15. An automatic rhythm playing apparatus as defined in claim 14 in which said lamp lighting means comprise a logic circuit which causes the lamp to be lighted by a rhythm pattern signal from said gate circuit having a pulse at the head of each measure during closing of a start switch, by a rhythm pattern signal from said rhythm pattern selection circuit means having a pulse at each predetermined note without activating said gate circuit during closing of a start synchronization switch which starts operation of the apparatus in synchronization with the start of playing of the electronic musical instrument and before performance of the electronic musical instrument, and by only the rhythm pattern signal from said gate circuit at the head of each measure during closing of the start synchronization switch and after the performance of the electronic musical instrument is started.

16. In combination with a memory having a plurality of output terminals from which signals are obtained in accordance with signal patterns stored therein and a plurality of input address terminals through which said signal patterns are selected at each of the output terminals, sound generating means connected to said output terminals for producing different sounds in response to signals from said output terminals, a source of clock pulses, binary decoding means connecting said source to the memory for cyclically applying said clock pulses to some of the input terminals producing signal pulses at selected ones of the output terminals, rhythm selection means connected to the other of the input terminals for applying constant signals to selected ones of said other of the input terminals, whereby the pulse signals at the selected ones of said output terminals cyclically drive the sound generating means in accordance with the selected signal patterns and gating means connected to the decoding means for modifying the pulse signals at the output terminals of the memory.

This invention relates to an automatic rhythm playing apparatus and, more particularly, to an automatic rhythm playing apparatus adapted for use with electronic musical instruments.

Automatic rhythm playing apparatus which have heretofore been used are complicated and large in size. Moreover, they are very expensive and their reliability is not sufficiently high.

It has therefore been considered impractical to incorporate the prior art automatic rhythm playing apparatus in a musical instrument which plays melody.

Further, there is a type of prior art automatic rhythm playing apparatus which starts in synchronization with an electronic musical instrument. According to this type of prior art apparatus, however, the player of the electronic musical instrument has no means to identify and ascertain rhythm tempo for adjustment thereof before or during performance of the electronic musical instrument but to listen to sounds actually issued from the rhythm playing apparatus. Accordingly, the player must operate the apparatus for trial hearing before performance of music and this apparently gives an awkward impression to general audience. Besides, it is not easy for the player to identify the rhythm tempo accurately during performance of music.

It is therefore an object of the present invention to provide an automatic rhythm playing apparatus in which an integrated circuit can be used for the principal part of the apparatus and therefore the whole apparatus can be made compact and incorporated in an electronic musical instrument while a much improved reliability is achieved.

It is another object of the invention to provide an automatic rhythm playing apparatus which can be produced at a remarkably low cost by a mass production method without sacrificing reliability.

It is another object of the invention to provide an automatic rhythm playing apparatus which can be produced by a simplified process of production and maintenance of which is easy.

It is another object of the invention to provide an automatic rhythm playing apparatus which can play various rhythms by adjusting the number and kind of the rhythms.

It is still another object of the invention to provide an automatic rhythm playing apparatus according to which rhythm tempo is indicated by lighting of a lamp whereby identification of rhythm tempo is made possible before and during playing of the electronic musical instrument which cooperates with the automatic rhythm playing apparatus.

Other objects and features of the invention will become apparent from the description made hereinbelow with reference to the accompanying drawings in which:

FIG. 1 is a block diagram showing one preferred embodiment of the automatic rhythm playing apparatus according to the invention;

FIG. 2 is a block diagram of another embodiment of the automatic rhythm playing apparatus according to the invention;

FIG. 3 is a block diagram showing one embodiment of the automatic rhythm playing apparatus according to the invention having a memory for storing rhythm patterns; and

FIG. 4 is a block diagram showing another embodiment of the automatic rhythm playing apparatus according to the invention which is constructed to indicate rhythm tempo by lighting an indication lamp.

Throughout FIGS. 1 to 4, the same component parts are designated by the same reference characters and numerals.

Referring first to FIG. 1, a clock pulse oscillator 1 has a tempo adjuster 1a. A desired tempo in various rhythms can be obtained by adjusting the tempo adjuster 1a. The output of the clock pulse oscillator 1 is supplied to a two stage frequency divider 10 consisting of flip-flops FF 1 and FF 2. The two stage frequency divider 10 produces pulses Pi having an interval corresponding to the minimum note (i.e. having the shortest period of time of sound) among notes used in various kinds of rhythms as shown in Table 1. ##SPC1##

The pulse signal Pi is applied to a dynamic counter 2. This dynamic counter 2 starts counting by closing of a start switch MS. The counter 2 is a four stage one comprising flip-flops FF 3 to FF 6 connected in series in four stages. The counter 2 successively receives the signal Pi from the frequency divider 10 and produces outputs A ₁ to A ₄ . When the counting is started, the state of outputs A ₁ to A ₄ is 0000. Then the signal Pi is successively applied to the counter 2 and the 16th pulse resets it. The counter 2 repeats the counting operation, being reset at every 16th pulse. Accordingly, there are 16 states of outputs A ₁ to A ₄ from 0000 up to 1111. The outputs A ₁ to A ₄ are fed to a decoder 3. The decoder 3 provides output only to an output line which corresponds to either one of the 16 states of outputs A ₁ to A ₄ . Decoders of this type capable of converting four binary inputs into 16 digital outputs are well known, as referred to for example in U.S. Pat. No. 3,610,801 to Fredkin et al (decoding matrix 19). This output of the decoder 3 is applied to a memory 4 as an address signal. A read only memory, for example, is used as the memory 4.

A rhythm selection circuit 6 is provided for obtaining an address signal proper to each of various rhythms. The rhythm selection circuit 6 has 16 switches S ₁ to S ₁₆ respectively corresponding to one of the rhythms of, for example, march, swing, waltz, slow rock, jazz rock, bosanova I, rumba, beguine, ballad, rock 2, rock 3, bosanova II, tango, cha cha cha, mambo and samba as shown in Table I. A state of outputs A ₅ to A ₈ which is peculiar to a selected rhythm can be obtained by closing a switch corresponding to the selected rhythm. There are 16 states of the outputs A ₅ to A ₈ , i.e. from 0000 to 1111. The selected state of the outputs among these 16 states is fed to a decoder 5. This state remains unchanged until the selected rhythm is switched off. The decoder 5 provides output only to an output line corresponding to the aforementioned state. This output of the decoder 5 is also applied to the memory 4 as an address signal.

A feedback circuit 12 for producing triplets has switches SW ₁ and SW ₂ which respectively are interlocked with the switch S ₂ corresponding to swing and the switch S ₄ corresponding to slow rock which need triplets as will be seen in Table I. When the switch SW ₁ or the switch SW ₂ is closed, the dividing ratio of the frequency divider 10 is changed to 1/3. The use of a feed back circuit to change the frequency division factor of a plural stage flip-flop type of frequency divider, is a well known technique, as disclosed for example in U. S. Pat. No. 2,881,333 to Pickard.

At addresses in the memory 4 to be accessed by the address signals from the decoders 3 and 5, information is stored in accordance with the note arrangement of the rhythms, i.e. march through samba which are shown in Table I. The information is successively read out by the address signals A ₁ to A ₈ thereby producing successive outputs for each percussion instrument sound. Since at this time the state of the address signals A ₁ to A ₄ is repeated at every 16th pulse, the state of outputs of the memory 4 is also repeated. Thus, measures of each rhythm shown in Table I are repeatedly obtained.

The outputs of the memory 4 are applied to a percussion instrument sound signal generating circuit 8 via a gate circuit 7 and capacitors C ₁ to C ₈ . The outputs B ₁ to B ₈ of the memory 4 respectively correspond to maracas, claves, cymbal, snare drum, high conga, low conga, bongo and bass drum. When the output is "1", the sound of the percussion instrument corresponding to the output is sounded from the percussion instrument sound signal generating circuit 8.

A gate signal waveshaping circuit 9 receives as inputs each signal from the dynamic counter 2, shapes the waveform of the signal into a sharp waveform and applies a gate pulse G which has been shaped in a sharp waveform to the gate circuit 7. The gate circuit 7 is provided for changing the output of the memory 4, in case the output is in the state of 1, into a pulse output having the same waveform as the gate pulse G when the gate pulse G is applied to the gate circuit 7. Since sounds of percussion instruments generally rise abruptly and decay rapidly, it is desirable to obtain a percussion instrument sound generating signal which approximates the sounds of the percussion instruments in waveform. That is, the waveshaping circuit 9 is provided for changing the output of the memory 4 which is nearly of a square wave into a pulse of a sharp waveform. The waveshaping circuit 9 also serves to enable the apparatus to play required rhythms by causing the outputs of the memory 4 to change into pulses of a sharp waveform because when the rhythm pattern of the memory 4 continues like , the outputs of the memory 4 would continuously be maintained at a low level and therefore produce no rhythm without the circuit 9.

The percussion instrument sound signal generating circuit 8 has 8 sound source circuits which respectively produce sound signals of bass drum, snare drum, cymbal, maracas, claves, bongo, high conga and low conga in response to the output signal of the memory 4. The percussion instrument sound signal produced in the circuit 8 is led to a common output line W.

Assume that the rhythm selection switch S ₁₃ is assigned to tango and S ₁₄ to cha cha cha. When the switch S ₁₃ is closed, the state of the outputs A ₅ to A ₈ becomes 0111 which state continues as long as the switch S ₁₃ is closed. When the switch S ₁₄ is closed, the state of the outputs A ₅ to A ₈ becomes 1011. Address input codes and outputs of the memory 4 for obtaining the rhythms of tango and cha cha cha are illustrated in Table II. In this table, numeral 1 indicates the output 1 of the memory 4 and the blank columns indicate the output 0 of the memory 4. ##SPC2##

As will be understood from the foregoing, the address codes consist of stationary or constant addresses for selecting a particular rhythm which remain unchanged once the address is selected and circulating or cyclically changing addresses which repeat the states 0000 through 1111 by the outputs supplied from the dynamic counter 2 via the decoder 3.

The employment of these address codes consisting of the stationary and circulating addresses enables the memory 4 to operate with a relatively small number of bits. In the present embodiment, there are 16 kinds of the addresses A ₁ to A ₄ and 16 kinds of the addresses A ₅ to A ₈ , totalling in 256 kinds of addresses. In the meanwhile, there are eight outputs B ₁ to B ₈ of the read only memory 4. Accordingly, the bit number of the memory 4 is 16×16×8=2,048. The use of read only memories of this type are well known as disclosed for example in U. S. Pat. No. 3,529,299 to Chung and requires only the routine effort of a person skilled in the art to adapt the memory for performing the desired functions in accordance with the instructions set forth in Table II.

Referring to FIG. 2, another embodiment of the automatic rhythm playing apparatus according to the invention will be described. A rhythm unit U ₁ comprises a dynamic counter 2A, decoder 3A, decoder 5A, memory 4A and gate circuit 7A which are of a construction similar to those shown in FIG. 1. A rhythm unit U ₂ is of a construction similar to the rhythm unit U ₁ . The rhythm unit U ₁ is connected to a rhythm selection circuit 6A from which it receives an address signal for designating rhythm. Likewise, the rhythm unit U ₂ is connected to a rhythm selection circuit 6B from which it receives an address signal for designating a rhythm. Pulses corresponding to a thirty-second note which is the minimum note among rhythm notes are applied from a two stage frequency divider 10 to the first stage flip-flop of the dynamic counter 2A. To the first stage flip-flop of the dynamic counter 2B are applied outputs of the second stage of the dynamic counter 2A, i.e. pulses corresponding to a 16th note.

Let it be assumed now that digital signals corresponding to a note arrangement of, for example, eight kinds of rhythms, i.e. march to beguine in Table I, are stored in the memory 4A whereas in the memory 4B are stored digital signals corresponding to a note arrangement of, for example, eight kinds of rhythms, i.e. ballad to samba in Table I. Switches S ₁ to S ₈ are ones respectively for selecting the rhythms of march to beguine and switches S ₉ to S ₁₆ are switches respectively for selecting the rhythms of ballad to samba. The switch S ₂ for selecting swing and the swicth S ₄ for selecting slow rock are respectively interlocked with switches SW ₁ and SW ₂ of a feedback circuit 12 for producing triplets.

In the construction shown in FIG. 2, if, for example, march is to be selected, the switch S ₁ of the rhythm selection circuit 6A is closed and then a start signal St is produced in a start signal generating circuit 11 for start-stop control of the counters 2A and 2B to which the circuit 11 is connected as shown. The starting and stopping of counters by signal generators is a well known technique involving the generation of an output potential capable of resetting the counters. Address signals A ₅ , A ₆ and A ₇ from the rhythm selection circuit 6A corresponding to the rhythm of march are supplied to the memory 4A via the decoder 5A. In the meanwhile, address signals A ₁ , A ₂ , A ₃ and A ₄ which are successively shifted in the counter 2A at arrival of each pulse signal Pi having a frequency corresponding to a thirty second note are fed to the memory 4A via the decoder 3A. Consequently, the contents of the memory 4A corresponding to the address signals are read out at arrival of each pulse signal Pi and pulse outputs of a note arrangement having tempo, time and repeated measures which correspond to the rhythm of march are successively supplied to terminals CY, SD and BD of a percussion instrument sound signal generating circuit 8 in the same manner as described above in conjunction with the previous embodiment. Accordingly, a composite signal which consists of bass drum, snare drum and cymbal sound signals is produced from the circuit 8.

Similarly, if a rhythm of ballad is to be obtained, the switch S ₉ of the rhythm selection circuit 6B is closed. In this case, pulse outputs of a note arrangement having tempo, time and repeated measures which correspond to the rhythm of ballad are successively supplied to terminals MA, CY, SD and BD of the circuit 8 in the same manner as in the unit U ₁ .

Thus, according to this embodiment, a desired rhythm output signal can be obtained by closing one of the switches of the rhythm selection circuit 6A or 6B.

In the construction of this embodiment, there are two separate rhythm units U ₁ and U ₂ which respectively receive address signals from the rhythm selection circuits. Accordingly, the number and kinds of selectable rhythms can be increased or decreased as desired by attaching or detaching one of the rhythm units, for example U ₂ . Further, since these units U ₁ and U ₂ can respectively be contained in separate packs whose terminals for connecting the units with outside circuits are entirely the same with each other, the unit U ₁ and the unit U ₂ are interchangeable with each other. As will be understood from the foregoing, the apparatus is expedient in the assembling thereof and is suitable for mass production by a simplified manufacturing process. Further, it will be apparent that the apparatus is easy to maintain. According to this embodiment, an automatic rhythm playing apparatus in which the memories 4A and 4B have a minimum number of bits required for playing desired rhythms or in which only particular rhythms the player needs are combined can be obtained by combining two or more of these interchangeable units each containing necessary number and kinds of rhythms. Besides, the memories 4A, 4B, the decoders 3A, 3B and 5A, 5B the counters 2A, 2B and the gate circuits 7A, 7B of the units U ₁ , U ₂ can easily be made by integrated circuits and, accordingly, the apparatus can be made sufficiently compact.

FIG. 3 shows another embodiment of the automatic rhythm playing apparatus according to the invention. A memory 13 consisting, for example, of a read only memory stores a plurality (e.g. 50 kinds in the present embodiment) of rhythm patterns.

The rhythm pattern is a common pattern of notes obtained through various rhythms irrespective of a kind of percussion instrument sound. A clock pulse oscillator 1, dynamic counter 2, decoder 3, rhythm selection circuit 6 and a decoder 5 are of a construction similar to those described with reference to FIGS. 1 and 2. The 50 kinds of rhythm pattern signals are read out of the memory 13 by 16 kinds of circulating signals from the decoder 3 and fed to a rhythm pattern selection circuit 17. In the meanwhile, stationary address signals A ₅ to A ₈ are supplied to the rhythm pattern selection circuit 17 from the rhythm selection circuit 6 via the decoder 5 by closing one of switches S ₁ to S ₁₆ corresponding to a desired rhythm in the same manner as described hereinabove. In the rhythm pattern selection circuit 17, rhythm pattern signals are selected in response to the signal from the decoder 5 and are led out as selected outputs among outputs B ₁ to B ₈ which, as in the previously described embodiments, are rhythm signals corresponding to maracas, claves, cymbal, snare drum, high conga, low conga, bongo and bass drum respectively. When the dynamic counter 2 has counted a certain predetermined number, for example, 12, a signal is fed to output B ₉ . The selected outputs of the rhythm pattern selection circuit 17 are supplied to a percussion instrument sound signal generating circuit 8 via a gate circuit 7 in the same manner as previously described. The percussion instrument sound signal generating circuit 8 provides a percussion instrument sound signal corresponding to the selected rhythm to a common output line. A waveshaping circuit 9 receives clock pulses from the clock pulse oscillator 1 and provides the clock pulses shaped in the waveform to the gate circuit 7 so as to close the gate circuit 7 at rising of each clock pulse for interrupting spike noise which occurs during shifting of the output in the decoder 3 and thereby preventing an erroneous operation of the percussion instrument sound signal generating circuit 8.

A one-shot multivibrator 14 provides a pulse by closing of a start switch SW. An AND circuit 15 satisfies logical product when it receives a power voltage through the start switch SW and the output B ₉ of the rhythm pattern selection circuit 17. The output terminals of the AND circuit 15 and the one-shot multivibrator 14 are connected to the input terminals of an OR circuit 16. Accordingly, when the output of the AND circuit 15 or the output of the one-shot multivibrator 14 is present, the dynamic counter 2 is reset.

By closing of the start switch SW, the one-shot multivibrator 14 is activated to provide the reset signal to the dynamic counter 2 via the OR circuit 16. This causes the dynamic counter 2 to count the clock pulses fed from the clock pulse oscillator 1 to form address signals composed of four stage outputs A ₁ to A ₄ which are supplied to the decoder 3. When one measure is to be divided into 16, the decoder 3 produces 16 kinds of signals, and when there are two measures, eight signals for each of the two measures. These signals are fed to the memory 13 which produces signals corresponding to the rhythm patterns from these 16 kinds of signals. The following Table III shows some examples of the rhythm patterns: ##SPC3##

In the above table CY represents cymbal and BD, bass drum.

It will be seen from the above Table III that CY and BD of waltz are of the same rhythm pattern and CY of bosanova and CY of mambo are of the same rhythm pattern. Accordingly, the two kinds of rhythm patterns which are common regardless of the kind of percussion instrument are stored in the memory 13. Rhythms which are the object of the rhythm playing apparatus can be classified into less than 50 kinds of rhythm patterns. Therefore, 50 terminals are sufficient as the output terminals of the memory 13.

The 50 output signals of the memory 13 are fed to the rhythm pattern selection circuit 17. In this rhythm pattern selection circuit 17, desired signals are selected and obtained from the 50 signals in response to its corresponding signal among 16 signals formed in the decoder 5 from the address signals A ₅ to A ₈ produced by closing of the switches S ₁ to S ₁₆ of the rhythm selection circuit 6. If, for example, waltz is selected by the rhythm selection switch S ₃ , the selection circuit 17 selects rhythm pattern signals required for waltz from the 50 rhythm pattern signals and provides a rhythm pattern signal corresponding to cymbal to the terminal B ₃ , one corresponding to snare drum to the terminal B ₄ and one corresponding to bass drum to the terminal B ₈ respectively.

Since waltz is a music of triple time, the rhythm pattern selection circuit 17 not only provides outputs to the output terminals B ₃ , B ₄ and B ₈ but leads out an output signal to the output terminal B ₉ . This signal is fed to the AND circuit 15 and, as a signal is supplied to the AND circuit 15 by closing of the start switch SW, a reset signal is supplied to the dynamic counter 2 via the OR circuit 16 as previously described.

If the time when the signal is led out to the output terminal B ₉ is synchronized with, for example, time when the dynamic counter 2 counts 12, four triplets signals may be formed.

The selected signals are fed to the gate circuit 7. The gate circuit 7 gates out signals by closing of the start switch SW. The signals produced by the gate circuit 7 are fed to the percussion instrument sound signal generating circuit 8. The percussion instrument sound signal generating circuit 8 in the present embodiment has eight sound sources. The sound sources oscillate eight kinds of signals including cymbal, snare drum, etc. For the rhythm of waltz three sound sources, i.e. cymbal, snare drum and bass drum are used. The outputs of the percussion sound signal generating circuit 8 are supplied to a sound system (not shown) so as to cause it to sound corresponding sounds.

The automatic rhythm playing apparatus according to the embodiment described with reference to FIG. 3 is suitable for adoption of an integrated circuit because the apparatus consists of a stationary type circuit except the switch portion and the sound source circuit and also because the number of terminals is held at the minimum. Further, according to this embodiment, forming of the percussion instrument sound signal is made by combination of the memory 13 for storing rhythm patterns which are obtained by classifying percussion instrument note patterns in various rhythms into common patterns regardless of the kind of percussion instrument and the rhythm pattern selection circuit 17 for selecting rhythm pattern signals corresponding to a desired rhythm from the memory 13. Consequently, the total bit number of the memory 13 and the selection circuit 17 is (16 × 50 = 800) + (16 × 8 = 128) = 928 bits. It will be understood that this embodiment is even more suitable for adoption of an integrated circuit than the embodiments shows in FIGS. 1 and 2 because the present embodiment requires less bit number than the other embodiments which require 2 ⁴ × 2 ⁴ × 2 ³ = 1,014 bits. If a MOS integrated circuit is used, the memory part will be easily constructed.

FIG. 4 shows another embodiment of the apparatus according to the invention. A feature of this embodiment is that rhythm tempo can be identified by lighting of an indication lamp before and during performance of music. The construction and operation of the component parts of this embodiment for producing predetermined rhythm sounds are substantially the same as the embodiment shown in FIG. 3 and so description thereof will be omitted. It should be noted, however, that a rhythm pattern selection circuit 18 in the present embodiment is different from the rhythm pattern selection circuit 17 shown in FIG. 3 in that a rhythm pattern signal having a pulse which corresponds to a desired note, e.g. a quarter note, always appears at a terminal B ₁₀ at the head of each measure and a rhythm pattern signal having a pulse which corresponds to a desired note, e.g. a quarter note, always appears at a terminal B ₁₁ at each desired note.

When a start switch SW is closed (at this time a start synchronization switch SF is open), voltage -V is applied to a one-shot multivibrator 26 via the switch SW and an OR circuit 25. The multivibrator 26 provides one pulse to a dynamic counter 2 as a reset pulse via an OR circuit 28. Thus, the dynamic counter 2 repeats counting operation, providing circulating address signals to a memory 13. The memory 13 produces 50 kinds of rhythm pattern signals in the manner as previously described. In the meanwhile, a stationary address signal is applied to a rhythm pattern selection circuit 18 by closing of a selected switch among rhythm selection switches S ₁ to S ₁₆ . This causes the rhythm pattern selection circuit 18 to provide a required rhythm pattern signal to terminals B ₁ to B ₁₁ . In the meanwhile, a gate circuit 7 to which the voltage -V is applied via the switch SW and an OR circuit 24 effects gate operation when it receives a gate pulse from a waveshaping circuit 9. Accordingly, the selected rhythm pattern signals from either of the terminals B ₁ to B ₈ of the rhythm pattern selection circuit 18 are fed to a percussion instrument sound signal generating circuit 8 for driving percussion instrument sound oscillators corresponding to the selected rhythm pattern signals which produce a predetermined rhythm sound.

When the start switch SW is closed, rhythm tempo can be identified by listening to a rhythm sound. To facilitate this identification, a lamp 22 is lighted at the head of each measure by application of the rhythm pattern signal (terminal B ₁₀ ) supplied to the gate circuit 7 to the lamp 22 through an OR circuit 20 and a buffer amplifier 21. Since the output of an inverter 23 is in the positive when the switch SW is closed, logical product is not made in an AND circuit 19. Accordingly, the rhythm pattern signal having a pulse at each quarter note does not appear at the output of the AND circuit 19.

When the start synchronization switch SF is closed, the rhythm playing apparatus does not make sound before playing of the electronic musical instrument. The apparatus only starts sounding of the rhythm sound from the start of the predetermined rhythm in synchronization with the start of playing of the electronic musical instrument. In this case, rhythm tempo cannot be identified by sound before performance of the electronic musical instrument starts. In the embodiment shown in FIG. 4, the rhythm tempo is indicated by lighting of the lamp both before and during performance of the electronic musical instrument to enable the player to adjust the tempo. In the state in which the synchronized start switch SF is closed, no key signal (-V) is applied to the OR circuit 24 from a key of the electronic musical instrument (not shown) before performance of music starts. Besides, voltage 0 is applied to the OR circuit 24 through resistance r. The OR circuit 24, therefore, provides no voltage to the gate circuit 7. Since the gate circuit 7 is in a non-operative stage, the percussion instrument sound generating circuit 8 is also in a non-operative state. The input of the inverter 23 at this time is also voltage 0 and so the output of the inverter 23 is in the negative. Accordingly, AND conditions of the AND circuit 19 are satisfied and a signal having a pulse at each quarter note is output from the AND circuit 19 and applied to the lamp 22 via the OR circuit 20 and the buffer amplifier 21. Consequently, the lamp 22 is lighted at each quarter note. This enables the player to identify and adjust rhythm tempo before performance of the electronic musical instrument.

When the player starts performance of the electronic musical instrument, the key signal (-V) which indicates the start of performance is applied to the one-shot multivibrator 26 via the switch SF and the OR circuit 25. This activates the one-shot multivibrator 26 to provide one pulse to the counter 2 via the OR circuit 28. Thus, the counter 2 is reset and repeat the counting operation. This provides circulating address signals to the memory 13 to produce 50 kinds of rhythm pattern signals therefrom. Then, the rhythm pattern selection circuit 18 selects rhythm pattern signals in response to a stationary address signal designating the selected rhythm so that the predetermined rhythm pattern signals appear at the selected terminals among the terminals B ₁ to B ₈ , B ₁₀ and B ₁₁ from the start of the rhythm. Simultaneously the gate circuit 7 is activated by application of the key signal (-V) indicating the start of performance to the OR circuit 24. Again, since the output of the inverter 23 is in the positive, the AND conditions of the AND circuit 19 are not satisfied and the signal at the terminal B ₁₁ is not gated out of the AND circuit 19. The rhythm pattern signal (having a pulse at the head of each measure) from the terminal B ₁₀ is applied to the OR circuit 20 via the gate circuit 7 and thereafter to the lamp 22 via the buffer amplifier 21. Accordingly, the lamp 22 is lighted at the head of each measure. This enables the player to identify tempo of the automatic rhythm playing apparatus during performance of the electronic musical instrument.

When a rhythm requiring triplets is selected, an output appears at the terminal B ₉ of the selection circuit 18 by closing of a predetermined rhythm selection switch. As this signal from the terminal B ₉ and the output of the one-shot multivibrator 26 are applied to the inputs of the AND circuit 27, the AND circuit 27 provides a reset signal to the counter 2 via the OR circuit 28 to reset the counting operation of the counter 2.

Although the invention has been described hereinabove in conjunction with specific embodiments, the invention of course is not confined to these embodiments but various changes and modifications may be made without departing from the spirit of the invention. For example, the number of stages in the dynamic counter 2 may be increased or decreased as desired and the number of selectable rhythms may also be increased or decreased without limiting it to 16. The rhythm pattern selection circuit may be modified according to the number and kinds of selectable rhythms. Further, the bit numbers of the memories 4 and 13 as well as the rhythm pattern selection circuit 18 may be determined at a desired number.