Automatic Arpeggio

Abstract

Automatic arpeggio and glissando effects are produced in a keyboard electronic musical instrument by entering note-selection signals in a single octave note storage register. The note storage register is acanned sequentially and repetitively at high speed under control of a note scan shift register. Scanning is suspended for tone generation each time a note-selection signal is shifted An octave counter, incremented at the completion of each scan of the note storage register, specifies the octave of the each generated tone. Different arpeggio modes are implemented, including a "harp" mode in which the octave backtracks each time a certain number of tones have been generated. In a glissando implementation, all notes of the chromatic or diatonic scale are generated in sequence, beginning and ending at notes selected on the instrument keyboard. Sequential tone generation is accomplished with circuitry like that for argpeggio. The glissando range is established by scanning the keyboard with a shift register containing a single 1 bit shift in unison with scanning of the note storage register and octave counter. Tone production is inhibited until the first depressed key is detected. Thereafter notes of the selected scale are generated in sequence until detection of the depressed key signifying the end of the glissando range. In a strum mode, the glissando is produced repetitively.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the automatic production of arpeggio and glissando effects in an electronic musical instrument.

2. Description of the Prior Art

Arpeggio is the playing of consecutive notes of a chord in rapid succession. Usually the chord is repeated through successive octaves. In glissando, consecutive tones of either the chromatic or diatonic scale are played in rapid sequence. Both effects are difficult to play, demanding considerable skill and dexterity of the musician. Automatic production of arpeggio and glissando adds these otherwise difficult effects to the repertoire of even a novice player. It is the principal object of the present invention to implement arpeggio and glissando automatically in an electronic musical instrument.

Certain features are desirable. These include ease of selection of the arpeggio chord, i.e., the notes to be included in the arpeggio. Another is flexability of the arpeggio mode. For example, the arpeggio chord may be repeated for all octaves from lowest to highest ("up-arpeggio") or from highest to lowest octave ("down-arpeggio"). Alternatively, the arpeggio may progress successively up and down either once or continuously. In a "harp" mode, the arpeggio chord is repeated through one octave and part of the next; the octave then is backtracked and tone production continued from the next note of the chord. Another object of the present invention is to implement each of these alternative arpeggio modes.

For automatic glissando production, a desirable feature is keyboard selection of the beginning and ending notes. Another object of the present invention is to implement such keyboard selection of the glissando range. In a strum mode, the glissando or arpeggio is produced repetitively.

Certain arpeggio systems for electronic organs are known. Illustrative is the automatic arpeggio described in the U.S. pat. No. 3,725,562 to Munch, Jr., et al. In that system, a series of tone gates is scanned by a sequential readout comprising a plurality of counter stages. Each such counter stage normally is configured as a monostable multivibrator with a time constant on the order of 30 microseconds. However, if a tone is to be supplied by the associated tone gate, the counter stage is reconfigured to act as a clock controlled bistable flip-flop.

To accomplish scanning, a pulse is rippled down the counter chain. For those stages corresponding to gates where no tone is present, the pulse is rapidly propagated by the one-shot counter configuration. However, at those counter stages for which a tone is to be generated, pulse propagation is delayed for a time interval established by a clock which controls the switching duration of the bistable flip-flop configured counter stage.

Another object of the present invention is to provide an arpeggio system which is less complex and more flexible than those known in the prior art.

SUMMARY OF THE INVENTION

These and other objectives are achieved by providing an arpeggio system wherein note selection signals corresponding to the desired arpeggio chord or glissando scale are entered in a single octave note storage register. The note storage register is scanned sequentially and repetitively at high speed under the control of a note scan storage register. Scanning is suspended for tone generation each time that a note-selection signal is detected. An octave counter, incremented at the completion of each complete scan of the note storage register, specifies the octave of the generated tones.

Alternative arpeggio modes are implemented. These include up- or down-arpeggio in which tone generation is terminated after a single scan of the complete instrument range; a single up-down mode in which the arpeggio is repeated once up and then once down through all octaves; and a continuous up-down mode in which arpeggio production is repeated in alternate directions. The "harp" mode is implemented by comparing the number of tones generated by the arpeggio circuit with a "harp count" equal to one greater than the number of notes in the selected arpeggio chord. Each time a comparison is obtained, the octave register is left shifted by one position to continue the arpeggio generation from a position one octave lower.

For glissando, the notes of the chromatic or diatonic scale are entered into the note storage register. The musician selects the beginning and ending notes of the glissando range by depressing corresponding keys on the keyboard. These keys are scanned by a glissando range shift register incremented in unison with the note scan shift register and the octave counter. Tone generation is enabled when the beginning note is detected by the glissando range shift register, and is terminated when the ending note is detected. In a strum mode, completion of the glissando range shift register scan provides a pulse which restarts the glissando operation.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention will be made with reference to the accompanying drawings wherein like numerals designate corresponding elements in the several FIGS.

FIG. 1 is an electrical schematic diagram of circuitry for producing arpeggio automatically in a keyboard electronic musical instrument.

FIG. 2 is a set of waveforms related to operation of the circuit of FIG. 1.

FIG. 3 is an electrical block diagram of circuitry for controlling the amplitude envelope of tones produced during an arpeggio controlled by the circuitry of FIG. 1.

FIG. 4 is an electrical block diagram of a modification to the circuit of FIG. 1 for producing an "up-down" arpeggio.

FIGS. 4A and 4B are electrical schematic diagrams of circuitry for initiating and terminating continuous up-down arpeggio.

FIG. 5 is an electrical block diagram of system for producing glissando automatically.

FIG. 6 is an electrical block diagram of a modification to the circuit of FIG. 5 for operation in the "harp" mode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention since the scope of the invention best is defined by the appended claims.

Operational characteristics attributed to forms of the invention first described also shall be attributed to forms later described, unless such characteristics obviously are inapplicable or unless specific exception is made.

The system 10 of FIG. 1 operates in conjunction with an electronic musical instrument to produce arpeggio automatically. The notes to be included in the arpeggio are selected on the instrument keyboard switches 11 and stored in a note storage register 12 which is a single octave in length. The note storage register 12 is scanned repetitively at high speed by a note scan shift register 13 and its associated circuitry, described below. An octave counter 14 is incremented each time the note storage register 12 is scanned completely.

Whenever a note-indicating signal is detected in the note storage register 12, scanning is suspended to permit tone generation for a time period established by a note duration monostable multivibrator (one-shot) 15. The detected note-selection signal from the storage register 12 is supplied via one of the lines 16 to the tone generators of the associated musical instrument, and indicates which note is to be produced. Simultaneously, a signal is supplied from the octave counter 14 via one of the lines 17 to the same tone generators. This signal specifies the octave of the produced note. In this manner, the successive note- and octave-indicating signals supplied to the associated musical instrument cause generation of an arpeggio beginning at the lowest octave and continuing through the highest octave of the instrument. The same selected notes are repeated in order for each octave.

In the embodiment of FIG. 1, the notes included in the arpeggio chord are selected by depressing the corresponding keys in any octave. For example, if an arpeggio including the notes C and E is desired, the C and E keys in any octave are depressed. This will cause corresponding C- and E-note-indicating signals to be entered into the note storage register 12 when a "start arpeggio" switch 19 is closed.

To this end, the note storage register 12 has twelve storage locations 12-1 through 12-12 corresponding to the twelve notes of the chromatic scale. The instrument keyboard switches include an extra set of contacts 11 each receiving a voltage +V via a buss 20. All switches 11 related to like notes are connected via a common buss to the corresponding input of the note storage register 12. Thus all of the switches C.sub.2, C.sub.3, C.sub.4. . .C.sub.7 are connected via a line 21-1 to the storage location 12-1. Similarly, each of the C.music-sharp. switches is connected via a line 21-2 to the storage location 12-2.

The note storage register 12 advantageously comprises a parallel-in, parallel-out-storage register wherein data is entered upon application of a "load" signal. In the system 10, a "load" signal 24 (FIG. 2) is supplied via a line 25 from a one-shot 26 when the start switch 19 is closed. Thus e.g., to load the notes C and E into the note storage register 12, the C and E keys in any octave are depressed (see waveshapes 27 and 28 in FIG. 2) and the start button 19 is closed. The corresponding note-selection signals then are stored in the locations 12-1 and 12-5 of the note storage register 12.

The note scan shift register 13 also comprises a parallel in-parallel out shift register having twelve storage locations 13-1 through 13-12 associated wth respective locations in the note storage register 12. A single 1 bit is loaded into the first location 13-1 upon occurrence of the "load" signal 24. This 1 bit is successively shifted through the shift register 13 and functions to enable readout of the corresponding location in the note storage register 12. Thus when the location 13-1 contains the 1 bit, an AND gate 30-1 is enabled to supply on a line 31-1 the contents of the note storage location 12-1. Similar AND gates 30-2 through 30-12, respectively associated with the note storage locations 12-2 through 12-12, are enabled when the single 1 bit in the shift register 13 is situated in the corresponding location 13-2 through 13-12. Thus as the 1 bit is shifted through the note scan shift register 13, any note-selection signals contained in the note storage register 12 will appear on the corresponding AND gate output lines 31-1 through 31-12. These lines enter an OR gate 32 which provides an output on a line 33 any time that a note-indicating signal is accessed from the note storage register 12. This output, supplied via an enabled AND gate 34 to a line 35 constitutes a "play" signal 36 (FIG. 2) which directs the associated musical instrument to generate the designated note.

The note scan shift register 13 is shifted at high speed by timing pulses 37 (FIG. 2) from a scan clock 38. These timing pulses are supplied via an AND gate 39 and a line 40 to the "shift" input of the register 13. Whenever a note-selectional signal is accessed from the storage register 12, the AND gate 39 is inhibited for the duration of note production. To this end, the AND gate 39 receives one enable input via a line 41 from an OR gate 42. The line 33 is connected via an inverter 43 to the OR gate 42. When no note-selection signal is accessed from the storage register 12, the line 33 will be low, hence the output of the inverter 43 will be high and an enable signal will be supplied via the OR gate 42 and the line 41 to the AND gate 39. As a result, pulses from the scan clock 38 cause shifting of the single 1 bit in the note scan shift register 13. Eventually the 1 bit will reach a location corresponding to that in which a note-selection signal is stored in the note storage register 12. As a result, the signal on the line 33 will go high, the output of the inverter 43 will go low, terminating the signal on the line 41 and disabling the AND gate 39. No more shift pulses reach the register 13, so that no scanning is suspended.

The signal which appears on the line 33 at the beginning of note production is supplied via an AND gate 45 to trigger the note duration one-shot 15. The output 46 (FIG. 2) is supplied via an inverter 47 to an "end of note" one-shot 48. This one-shot 48 provides a short duration pulse 49 (FIG. 2) on a line 50 at the end of the duration of note production. Occurrence of this pulse 49 enables the AND gate 39 to provide at least one more shift pulse to the shift register 13. That is, note scanning is restarted.

If no note-selection signal is present in the next scanned location of the note storage register 12, the signal on the line 33 will go low, enabling the supply of additional shift pulses to the note scan shift register 13. On the other hand, if the next scanned location of the note storage register 12 does contain a note selection signal, the line 33 will stay high, and scanning again will be inhibited. The duration during which this new note is generated again will be established by the one-shot 15. To insure, this, the end of note pulse 49 on the line 50 is supplied via an inverter 51 to an enable input of the AND gate 45. As a result, the input to the one-shot 15 will be interrupted briefly at the end of the prior note. This insures that the one-shot 15 will function properly to time the generation of two notes designated by note-selection signals in adjacent storage locations of the note storage register 12.

In the embodiment of FIG. 1, the arpeggio begins at the lowest octave (typically octave 2) and continues through the highest octave (e.g., octave 7). To accomplish this, the octave counter 14 contains six storage locations 14-1 through 14-6 each associated with a respective octave 2 through 7. At the start of arpeggio production, the "load" signal 24 on the line 25 causes a single 1 bit to be entered into the first shift register position 14-1 of the octave counter 14. The corresponding output signal on the line 17-1 indicates that notes are to be produced in octave 2.

At the end of each complete scan of the note storage register 12, the single 1 bit in the note scan shift register 13 is reentered into the first location 13-1 via a line 53. The signal on the line 53 also is provided to the shift input of the octave counter 14, which advantageously comprises a parallel-in, parallel-out shift register. Occurrence of the pulse on the line 53 causes the single 1 bit in the octave counter 14 to be advanced to the next location. The resultant signals on the lines 17 designate the octave of the notes to be generated in unison with repetitive scanning of the note storage register 12. Arpeggio production is terminated after scanning in the highest octave of the musical instrument.

To this end, an "enable play" flip-flop 54 is set to the 1 state by the "load" pulse 24 at the beginning of arpeggio production. The resultant "enable play" signal 55 (FIG. 2) on a line 56 enables the AND gates 34 and 39 during arpeggio production. When the highest available note of the associated musical instrument has been scanned, the flip-flop 54 is reset to the 0 state, terminating the "enable play" signal 55 and disabling the AND gates 34 and 39. No further scan clock 38 pulses are supplied to the shift register 13, thereby terminating the scanning operation. Provision of the "play" signals on the line 35 also is terminated.

In the system 10, the flip-flop 54 is reset after scanning of the highest available note C.sub.7 (the note C in octave 7). This is accomplished by providing the C.music-sharp. scanning signal on the line 16-2 and the octave 7 signal on the line 17-6 to an AND gate 57. Accordingly, an output from the AND gate 57 occurs just subsequent to scanning of the highest note C.sub.7. This output supplied via a line 58 resets the "enable play" flip-flop 54 to terminate he arpeggio.

Operation of the system 10 (FIG. 1) is illustrated by the waveforms of FIG. 2, most of which have been described above. The lines 60 and 61 respectively designate the contents of the note scan shift register 13 and the octave counter 14 during the arpeggio operation. The curve 62 indicates the periods during which the AND gate 39 is enabled to provide shift pulses to the note scan shift register 13.

During an arpeggio, each individual note is produced for a relatively short time duration. During this note duration it may be desirable to shape the amplitude envelope so that the tone exhibits pleasing attack and decay characteristics. Such amplitude envelope control is provided by the circuitry 60 of FIG. 3 which functions in conjunction with the arpeggio system 10 of FIG. 1.

Attack and decay is accomplished by providing successive amplitude scale factors from a memory 61 via a line 62 to the associated musical instrument. These scale factors are selected to provide the desired attack and decay characteristics. In the musical instrument, an appropriate circuit such as a multiplier scales the amplitude of the generated note by the provided scale factor. As a result, the generated tones exhibit the desired attack and decay characteristics. For example, in a COMPUTOR ORGAN such as that described in the inventor's corresponding patent application Ser. No. 225,883 filed Feb. 14, 1972, and now U.S. Pat. No. 3,809,786, the harmonic coefficients used to establish the amplitudes of the generated tones are multiplied by the attack/decay scale factors supplied from the circuit 60 (FIG. 3) to accomplish envelope scaling.

The circuit 60 replaces the one-shot 15 and the inverter 47 of FIG. 1. Instead, the output of the AND gate 45 is connected via a line 63 to an AND gate 64 which gates scale factor timing pulses from an attack/decay rate clock 65 to the shift input 66 of an attack/decay shift register 67 used to access sequentially the scale factor memory 61. An output line 68 from the final position 67-0 of the shift register 67 is connected to the input of the end-of-note one-shot 48 (FIG. 1). The shift pulses supplied via the line 40 to the note scan shift register 13 also are provided to the "load" input of the attack/decay shift register 67. The effect is to enter a single 1 bit into the first position 67-1 of the shift register 67 at the time that each location of the note storage register 12 is scanned. Thus if that storage position contains a note selection signal, the circuit 60 is conditioned to begin readout of the attack/decay scale factors.

Appearance of a note selection signal on the line 33 produces a concomitant signal on the line 63 which enables the AND gate 64. Attack/decay rate pulses are supplied via the line 66, causing the single 1 bit to shift from position to position in the attack/decay shift register 67. The memory 61 stores the appropriate attack and decay scale factors in successive storage locations 61-1 through 61-n having a one-to-one correspondence with locations 67-1 through 67-n in the shift register 67. The memory 61 is designed so that the scale factor in the storage location corresponding to the present location of the single 1 bit in the shift register 67 is read out onto the line 62. With this arrangement, the successive attack and decay scale factors will be supplied via the line 62 to the associated musical instrument as the single 1 bit is shifted through the shift register 67. The produced note will have a resultant amplitude envelope defined by the scale factors which are supplied at a rate established by the clock 65.

After all of the scale factors have been supplied to the associated instrument, the 1 bit reaches the end position 67-o. Accordingly, a signal is supplied via the line 68 to the end of note one-shot 48 (FIG. 1) thereby terminating note production. In this manner, the duration of tone production is controlled by the attack/decay shift register 67 in conjunction with the rate clock 65.

In the embodiment of FIG. 1, the produced arpeggio begins at the lowest octave and ends at the highest octave. By using the optional circuitry 70 of FIG. 4, an "up-down" arpeggio is obtained. The notes first are produced going upward from the lowest to the highest octave, followed by a reverse or downward arpeggio starting from the highest octave and ending with notes of the lowest octave.

To implement such up-down arpeggio, the note scan shift register 13 (FIG. 1) is replaced by a shift register 13' capable of either right or left shifting. Similarly, the octave counter 14 is implemented by a right/left shift register 14' (FIG. 4). The shift register 13' and 14' each have a right/left control input. When a low or 0 signal is supplied to this input, a right shift occurs each time a shift pulse is received. If a high or binary 1 signal is supplied to the control input, a left shift occurs.

Using the optional circuitry 70, operation during the up arpeggio is identical to that described in FIG. 1. During this time, a 0 or right shift signal is supplied via a line 71 to the right/left control inputs of the shift registers 13' and 14'. This control signal is supplied from an "up-down" flip-flop 72 which initially is set to the 0 or "up" state by the load signal 24 present on the line 25 at the start of the arpeggio.

Upon completion of the up-arpeggio, an output is obtained from the AND gate 57. In the embodiment of FIG. 4, this output is not supplied to the flip-flop 54 as shown in FIG. 1, but rather is supplied to the set (S) input of the up-down flip-flop 72. As a result, this flip-flop 72 is set to the 1 or "down" state upon completion of the up-arpeggio. When so set, the flip-flop 72 provides a 1 signal on the line 71 which conditions the shift register 13' and 14' for left shifting. In this manner, both the notes and octaves are scanned from the highest to the lowest positions during the down-arpeggio.

The octave counter 14' is shifted once for each complete scanning of the note storage register 12. In the circuit 70, shift pulses are supplied to the octave counter 14' via a line 73 from an OR gate 74. During the up-arpeggio, the line 53 is connected to the line 73 via the OR gate 74 and an AND gate 75 enabled by the 0 output from the flip-flop 72. Thus, the octave counter 14' is incremented in exactly the same manner as that described in FIG. 1.

During the down-arpeggio, the single 1 bit in the note scan shift register 13 is shifted to the left, starting from the location 13-12 and ending at the location 13-1. The signal then is re-entered in the highest position 13-12 via a reset line 76. The same signal on the line 76 is supplied to the shift input of the octave counter 14' via the OR gate 74 and an AND gate 77 enabled by the "1" signal on the line 71. In this manner, the octave counter 14' is shifted to the left (downward) each time a complete downward scan of the note storage register 12 has been completed.

To terminate the up-down arpeggio, the octave counter 14' has an extra storage location 14-0 at its low end. Thus, after complete scanning of the lowest octave, the single 1 bit in the octave counter 14' will be left shifted into this end position 14-0. Accordintly, an output will be provided from an AND gate 78 enabled by the 1 signal on the line 71. This output is supplied via the line 58 to the reset (R) input of the "enable play" flip-flop 54 (FIG. 1). Occurrence of the signal on the line 58 resets this flip-flop 54 to terminate arpeggio production.

The circuits of FIG. 4A and 4B permit implementation of continuous up-down arpeggio. Unlike the circuit of FIG. 4, which terminates after a single up and down scan, the circuit 80 of FIG. 4A permits the arpeggio to continue so long as a switch 81 is closed. In the circuit 82 of FIG. 4B, the arpeggio begins when a "start" switch 83 is depressed. The arpeggio continues alternately up and down until terminated by depression of an "end" switch 84.

The circuit 80 (FIG. 4A) provides an input to the "start" one shot 26 (FIG. 1) in place of the switch 19. That is, the switch 19 is not used, and the line 85 from an inverter 86 is connected to the input of the one shot 26. When the switch 81 is open, the inverter 86 receives a high signal represented by the voltage +V supplied via a resister 87. As a result, the line 85 is low. When the switch 81 is depressed, the input to the inverter 86 goes low, since it is now connected to ground. Accordingly, a high output occurs on the line 85 which triggers the one shot 26 to start the arpeggio.

To terminate the arpeggio, the output of a one shot 88 is supplied via a line 58b to the reset (R) input of the "enable play" flip-flop 54 in place of the output from the AND gate 78 (FIG. 4). While the switch 81 is closed, the one shot 88 receives a low input. As soon as the switch 81 is opened, a high input is applied to the one shot 88, resulting in production of a pulse on the line 58b which resets the "enable play" flip-flop 54 to the 0 state, thereby terminating the arpeggio. The output from the AND gate 78 (FIG. 4) advantageously is connected to the reset (R) input of the "up-down" flip-flop 72 in place of the line 25. This insures that if the switch 81 remains closed for several up-down cycles, the flip-flop 72 will be reset at the end of each down arpeggio. This switch 81 may be knee-controlled.

The circuit 82 (FIG. 4B) is connected similarly to that of FIG. 4A. However, here the one shot 88 is triggered by a high pulse which results when the input to an inverter 89, connected via a resistor 90 to the +V voltage source, is grounded by closure of the switch 84.

Glissando is produced by the circuit 93 of FIG. 5 which is a modification of the system 10 of FIG. 1. Either chromatic or diatonic glissando is selected by closing one of the respective switches 94 or 95. The glissando range is established by depressing two keys to close a corresponding pair of auxiliary switch contacts 11a. When the start switch 19' then is closed, the circuit 93 produces a glissando automatically, beginning at the lowest note selected by the keyboard switches 11a and continuing to a higher note corresponding to the other of the closed switches 11a. If chromatic glissando is selected, every note in the selected glissando range will be played in order. If diatonic glissando is selected, only the notes of the diatonic scale are produced, beginning and ending at the notes selected via the key contacts 11a.

For glissando, note-selection signals are supplied to the note storage register 12 via circuitry including the switches 94 and 95. For chromatic glossando, closure of the switch 94 applies inputs to all of the note storage register positions 12-1 to 12-12 via a line 96 and the twelve OR gates 97-1 through 97-12 associated with the respective storage register locations. For diatonic glissando, closure of the switch 95 provides a note-selection signal to each location of the note storage register 12 associated with a note (C, D, E, F, G, A and B) of the diatonic scale. The arpeggio key contact busses 21-1 through 21-12 also may be connected to the note storage register 12 via the OR gates 97-1 through 97-12. However, during glissando production the voltage would be removed from the buss 20 (FIG. 1) so that the note storage register 12 is only loaded with the appropriate chromatic or diatonic glissando note selections signals.

Glissando range selection utilizes an extra set of keyboard contacts 11a separate from the arpeggio contacts 11 (FIG. 1) but operated by the same keyboard. The selected beginning and end keys of the glissando range are held down (i.e., closed) during glissando production. The position of these keys is detected by a glissando range shift register 98 which scans the keyboard in unison with glissando note production.

To this end, the glissando range shift register has a number of storage locations 98-l through 98-m corresponding to the number of keys on the instrument keyboard. For example, in an electronic organ having a keyboard extending from C.sub.2 through C.sub.7, the shift register 98 would have m=61 register positions. When the start glissando switch 19' is closed, a single 1 bit is loaded into the first position 98-l of the shift register 98. This 1 bit is shifted through the register 98 by the same shift pulses on the line 40 used to advance the note scan shift register 13. Thus the 1 bit in the shift register 98 always is situated in the register position corresponding to the note currently available for production; as specified by the contents of the note scan shift register 13 and the octave counter 14.

In the glissando circuit 93, the AND gate 34 is enabled by a "glissando enable" flip-flop 99 rather than by the "enable play" flip-flop 54. When the start glissando switch 19' is closed, the "glissando enable" flip-flop 99 is reset to the 0 state, thereby disabling the AND gate 34. No "play" signal will be supplied to the associated musical instrument until the "glissando enable" flip-flop 99 is set to the 1 state upon detection of the selected beginning note of the glissando range. Such detection is facilitated by the glissando range shift register 98 in conjunction with the switch contacts 11a and a set of AND gates 101-l through 101-m each associated with a respective one of the switch contacts 11a.

When the 1 bit in the glissando range shift register 98 first reaches a location corresponding to a closed switch 11a, the corresponding AND gate 101 is enabled, providing a signal via an OR gate 102 to the set (S) input of the "glissando enable" flip-flop 99. The resultant 1 output from that flip-flop on the line 103 enables the AND gate 34 to provide the "play" signals to the associated musical instrument. This starts generation of the glissando tones. Successive tones in the chromatic or diatonic scale then are generated in succession, with the duration of each note being established by the one-shot 15.

Eventually the 1 bit in the glissando range shift register 98 will reach a position corresponding to the next closed switch contact 11a, which defines the end of the glissando range. As a result, another signal will be provided to the OR gate 102 via one of the AND gates 101. This signal will reset the "glissando enable" flip-flop 99 to terminate glissando production.

The resetting occurs in the following way. The output from the OR gate 102 is anded with the 1 flip-flop output on the line 103 by an AND gate 104. The output of this gate 104 is supplied via a line 105, and OR gate 106 and a line 107 to the reset (R) terminal of the "glissando enable" flip-flop 99. In FIG. 5, the keyboard switches D.sub.2 and F.sub.5 are closed. For this example, the glissando range begins at the note D.sub.2 and ends at the note F.sub.5. At the beginning of glissando operation, after the start switch 19' has been closed but before the starting note of the glissando range has been detected, the note scan shift register 13 and the glissando range shift register 98 are shifted at a rapid rate. This is accomplished by providing the 0 output of the "glissando enable" flip-flop 98 via a line 108 to the input of the OR gate 42'. The resultant output on the line 41 enables the AND gate 39 to provide shift pulses from the scan clock 38 to the line 40. The requisite high speed shifting is achieved.

The glissando circuit 93 of FIG. 5 readily may be modified to provide a "strum" effect wherein the notes in the selected glissando range are produced repetitively. In the modification, the shift register 98 has an extra position 98-n. After completion of scanning the entire keyboard, the single 1 bit in the register 98 will be shifted to this final position 98-n. The resultant signal on a line 109 is provided as an alternative trigger to the start one-shot 26. This causes generation of another "load" pulse 24, initiating a new glissando cycle. By providing an optional delay circuit 109a in the line 109, the new cycle will not start immediately. Tone generation continues repetitively in this strum mode unitl the keys establishing the glissando range are released. Thereafter, tone generation will cease, since the "glissando enable" flip-flop 99 remains in the reset or disable state.

Operation in the harp mode is facilitated using the circuit 110 of FIG. 6 in conjunction with the circuit 10 of FIG. 1. In this mode, instead of playing notes straight up and/or down the keyboard, after one octave plus one note, the octave counter 14 backtracks one octave. Thus e.g., if the selected arpeggio notes are C, E and G, the sequence produced in the harp mode will be:

C.sub.2 E.sub.2 G.sub.2 C.sub.3 E.sub.2 G.sub.2 C.sub.3 E.sub.3 G.sub.2 C.sub.3 E.sub.3 G.sub.3 C.sub.3 . . .

Such harp mode operation is achieved by counting the number of selected arpeggio notes and adding one to this number to obtain a "harp count." The octave register 14 then is left shifted by one position each time the number of generated tones equals the "harp count." This operation is carried out by the circuit 110.

A counter 111 is incremented each time a tone is generated. This is accomplished by supplying the output of the note duration one shot 15 via a line 112 to the "count" input of the counter 111.

At the beginning of arpeggio generation, the "load" pulse 24, supplied via the line 25 and an OR-gate 113 is used to reset the counter 111 to zero. The "load" pulse also sets a flip-flop 114 to the 1 state. During tone generation in the lowest octave, the counter 111 is incremented each time a note is produced. Thus when the single 1 bit reaches the final position 13-12 of the note scan shift register 13 (FIG. 1), the contents of the counter 111 equals the number of selected apreggio notes. This number is stored in a storage register 115. To do this, the scan reset pulse on the line 53 (FIG. 1) is supplied via an AND gate 116, enabled by the 1 output of the flip-flop 114, to the "load" terminal of the storage register 115. This causes the contents of the counter 111 to be loaded via a line 117 into the storage register 115. The signal on the line 53 also resets the flip-flop 114 to 0. This disables the AND gate 116 so that the contents of the storage register 115 will remain unchanged throughout the remainder of the harp mode arpeggio generation.

The value 1 is added to the contents of the storage register 115 by an adder 118. The sum, corresponding to the "harp count," is provided via a line 119 to a first input of a compare circuit 120. The second input to the comparator 120 is the contents of the counter 111 supplied via the line 117.

Each time that the circuit 10 (FIG. 1) has directed generation of a number of notes equal to the "harp count," the contents of the counter 111 will equal the number provided on the line 119. As a result, the comparator 120 provides an output signal on a line 121 which causes the octave counter 14 to left shift by one position. The signal on the line 121 also resets the counter 111. Note generation continues with the next sequential note, but one octave lower than the last generated. The resultant tone sequence is exactly that given above for the harp mode.

Various alternative embodiments readily are apparent. For example, the arpeggio circuit of FIG. 1 may be configured for down-arpeggio, instead of the up-arpeggio shown, by loading the 1 bits at the high end of the note scan shift register 13 and the octave counter 14. Left shifting in each register 13 and 14 will produce the down-arpeggio. The attack/decay amplitude envelope circuitry of FIG. 3 alternatively may be used in conjunction with the glissando circuit of FIG. 5. In the strum mode, notes other than those of chromatic or diatonic scale may be entered in the note storage register 12, so that any desired chord may be strummed.

Intending to claim all novel, useful and unobvious features shown or described, the applicant:

Claims

I claim:

1. Apparatus, useful in conjunction with an electronic musical instrument, for producing arpeggio and like effects, comprising:

a note storage device containing note-selection signals indicative of an arpeggio chord,

note scanning means for repetitively sequentially scanning said note storage device, said scanning being suspended to permit tone production each time that a note-selection signal is detected in a scanned location of said note storage device, and

play direction means, operative upon detection of a note-selection signal, for directing said musical instrument to produce a tone, the note and octave of said tone being established respectively by the scanned location containing said detecting note-selection signal and by the number of times said storage device has been scanned repetitively.

2. Apparatus according to claim 1 wherein said note storage device is a single octave in length, and further comprising;

keyboard switch means facilitating selection of said arpeggio chord in any octave of a keyboard of said musical instrument, and

start means for causing entry into said single octave note storage device of note-selection signals corresponding to said keyboard selected arpeggio chord and for initiating said scanning to start arpeggio production.

3. Apparatus according to claim 2 wherein said notestorage device comprises a storage register having 12 storage locations corresponding to the 12 notes of the chromatic scale, and wherein said keyboard switch means comprises a set of contacts on said keyboard connected so that the closure of a key contact for a particular note in any octave will result in entry of a signal into that single storage location corresponding to said particular note.

4. Apparatus according to claim 1 wherein said note scanning means includes an octave counter the contents of which designates the octave of said produced tone, the contents of said octave counter being set to the first octave of the produced arpeggio upon imitation of scanning, the contents of said octave counter being advanced by one upon completion of each sequential scanning of said note storage device.

5. Apparatus according to claim 4 wherein said note scanning means further includes;

a note scanning device having 12 positions corresponding respectively to the 12 storage locations in said note storage device,

shift means, including a scan rate clock, for actuating said twelve positions sequentially, and

detector means for detecting the presence of a note-selection signal in the signal storage location corresponding to the actuated position of said note scanning device.

6. Apparatus according to claim 5 further comprising;

up-down arpeggio control means for selectively enabling up arpeggio or down arpeggio, said control means initially setting said note scanning device and said octave counter to their lowest position and enabling each to be incremented during said scanning to produce up arpeggio, said control means initially setting said note scanning device and said octave counter to their highest position and enabling each to be decremented during said scanning to produce down arpeggio.

7. Apparatus according to claim 6 wherein said arpeggio control means successively, alternately enables up and down arpeggio, together with start-stop switch means for initiating and terminating the resultant continuous up-down arpeggio.

8. Apparatus according to claim 5 further comprising;

note duration timing means, operative upon detection of a note-selection signal by said detector means, for inhibiting sequential actuation of said scanning device positions for a preset time interval during which said play direction means directs tone production.

9. Apparatus according to claim 5 further comprising;

attack/decay control means, operative upon detection of a note-selection signal by said detector means, for sequentially providing a set of attack/decay scale factors for use by said musical instrument to establish the envelope of the produced tone corresponding to said note-selection signal.

10. Apparatus according to claim 9 wherein said shift means sequentially actuates said twelve positions at a high speed established by said scan rate clock, together with means for suspending said sequential actuation for a note production interval beginning with detection of a note-selection signal and ending when said set of attack/decay factors has been provided to said musical instrument.

11. Apparatus according to claim 4 for producing arpeggio in the harp mode, comprising:

harp counter means, responsive to said play direction means for counting the number of notes in one octave of said arpeggio chord and for establishing a "harp count" related thereto,

produced tone counting means for counting the number of tones sequentially directed for production by said play direction means, and

decrementing means for decrementing said octave counter each time that the number of sequentially produced tones counted by said produced tone counting means equals said harp count, and for resetting said produced tone counting means.

12. Apparatus according to claim 1 for producing glissando, comprising;

scale means for entering into said note storage device note-selection signals indicative of notes of a scale, and

glissando range control means, cooperating with said play direction means, for enabling sequential tone production only of notes within a selected glissando range.

13. Apparatus according to claim 12 for producing strum effects, comprising:

restart means, cooperating with said glissando range control means, for restarting said apparatus to repeat operation after completion of enabled tone production within said selected glissando range.

14. Apparatus for producing arpeggio automatically in a keyboard electronic musical instrument, comprising:

note storage means, having a number of storage locations corresponding to the number of notes in a single octave of a musical scale, for storing signals in locations corresponding to selected notes independent of octave,

scanning means for sequentially scanning all of said storage locations at rapid rate and for suspending said scanning for a time period permitting tone generation each time a stored note-indicating signal is detected in a scanned storage location, and

repetitive scan control means, operative upon each completion of sequential scanning of said storage locations and including an octave counter incremented at each such completion, for causing said scanning means again to scan said storage locations, the detected note-indicating signal and the contents of said octave counter together specifying the note to be generated by said instrument during each respective tone generation time period, the repetitively generated notes thus constituting an arpeggio.

15. Apparatus according to claim 14 wherein said note storage means comprises a note storage register having twelve storage locations, and wherein said scanning means comprises;

a note scan shift register having twelve positions,

a scan clock providing pulses at high speed,

a logic gate connected, when enabled, to supply pulses from said scan clock to the shift input of said note scan register,

load means for loading a single 1 bit into one position of said note scan shift register and for enabling said logic gate, and

note duration timing means, operative upon detection of a note-indicating signal in the storage location corresponding to the shift register position currently containing the signal 1 bit, for disabling said logic gate and hereby suspending said scanning during said tone generation time period.

16. Apparatus according to claim 15 further comprising; up-down arpeggio control means, cooperating with said load means, for loading said single 1 bit into one end position of said note scan shift register and for conditioning said shift register and said octave counter each to be incremented during an up arpeggio cycle, and for loading said single 1 bit into the other end position of said note scan shift register and for conditioning said shift register and said octave counter each to be decremented during a down arpeggio cycle.

17. Apparatus according to claim 16 wherein said up arpeggio control means successively conditions said note scan shift register and said octave counter alternately for up and down arpeggio, together with start-stop switch means for initiating and terminating the resultant alternate up and down arpeggio.

18. Apparatus according to claim 14 further comprising;

a set of keyboard contacts wired so that like notes in different octaves are connected to a common buss associated with a respective storage location in said note storage means, and

load means, operative at the start of arpeggio, for entering note-indicating signals into locations of said storage means for notes selected at any octave of said keyboard via the contacts and busses associated with the selected notes.

19. Apparatus according to claim 14 for producing harp arpeggio, comprising:

a note counter, operative during the first sequential scanning of said storage locations, for counting the number of produced tones,

harp count storage means for providing a "harp count" equal to said counted number of produced tones plus a constant,

said note counter being operative during subsequent sequential scanning of said storage locations to count the number of tones produced since resetting of said counter, and

comparator means for comparing the counted number of tones since resetting with said "harp count" and for decrementing said octave counter and resetting said note counter each time an equal comparison is obtained.

20. Apparatus for producing glissando automatically in an electronic musical instrument, comprising;

note scanning means for repetitively, successively providing signals indicative of all notes in a single octave of a musical scale,

an octave counter, preset to a certain value and advanced by one each time said note scanning means provides signals indicative of all notes of an octave, said indicative signals and the contents of said octave counter repsectively specifying the note and octave of each tone produced by said musical instrument,

range selection means for selection of the starting and ending notes of said glissando,

glissando range scanning means, actuated at the same time as said note scanning means, for scanning the same musical range in unison with said note scanning means and said octave counter, and

tone inhibit means for preventing tone production by said musical instrument until said glissando range scanning means detects the starting note selected by said range selection means, and thereafter enabling such tone production until detection by said range scanning means of said selected ending note.

21. Apparatus according to claim 20 wherein said note scanning means comprises circuitry for selectively providing note-indicative signals for either the chromatic of diatonic scale, and wherein said range selection means comprises a set of contacts actuated by a keyboard of said musical instrument.

22. Apparatus according to claim 20 wherein said glissando range scanning means comprises;

a counting device having a range equal to said same musical range,

scan clock means for providing high speed scan pulses to both said counting device and said note scanning means to scan said musical range at a high speed prior to detection of said starting note, and

note duration timing means for advancing said scanning by said note scanning means and said glissando range scanning means at a relatively much slower rate during glissando production between detection of said starting and ending notes.