Title:
BASS REGISTER KEYING SYSTEM
United States Patent 3558794
Abstract:
A note an octave or two octaves below the lowest note of a chord played on the accompaniment manual of an organ is produced by a frequency-dividing flip-flop triggered by a signal selected from the chord notes by use of a preferential type of mechanical switch. This switch is comprised of a series of movable contacts parallel to, and actuated respectively by, playing keys in the lower section of the accompaniment manual. Thereby, when a chord is played, a note corresponding only with the lowest or root note of the group of keys actuated is sounded. The pitch range of such a switch is only about seven semitones, so if, as is preferable in a root tone system, about an octave and a half of semitones is to be included, some means must be provided for extending the range to about 19 semitones. The preferred extension, in accordance with the invention, is to parallel the movable contacts with ordinary make-break key switches actuating diode gates preferentially biased by scaling voltage dividers. Means are provided to have one preferential system override the other, so that a double preference is exercised, operative simultaneously over the entire 19 semitones.
US Patent References:
Electrical musical instrument
Dorf - June 1962 - 3040612
Chorus effects in electronic organ
Martin - November 1965 - 3215767
Electronic musical instrument having one or more keyboards
Wehrmann - July 1966 - 3260784
Tone generator with directivity cues
Hurvitz - August 1967 - 3336432
Electrical musical instrument
Dorf - June 1962 - 3040612
Chorus effects in electronic organ
Martin - November 1965 - 3215767
Electronic musical instrument having one or more keyboards
Wehrmann - July 1966 - 3260784
Tone generator with directivity cues
Hurvitz - August 1967 - 3336432
Application Number:
04/862194
Publication Date:
01/26/1971
Filing Date:
09/30/1969
View Patent Images:
Export Citation:
Assignee:
D. H. Baldwin Company (Cincinnati, OH)
Primary Class:
Other Classes:
84/644, 84/675, 984/348
International Classes:
G10H1/38; G01H1/06
Field of Search:
84/1.01,1.17,1.19,[A,B,FD,N]
Primary Examiner:
Ray W. E.
Parent Case Data:
This application is a division of application, Ser. No. 468,767, entitled "Bass Register Keying System" filed July 1, 1965, now U.S. Pat. No. 3,470,306.
Claims:
I claim
1. In an electronic organ:
1. In an electronic organ:
Description:
The invention concerns electronic organs and pertains particularly to a keying system for playing automatically, when a chord is played on a manual keyboard, lower register root tones normally heard by playing a pedal keyboard.
Piano players called upon to play electronic organs and novice organ players often have difficulty, while playing on manual keyboards, in concurrently playing pedal notes called for in organ music. Usually such players will be playing a chord on an accompaniment manual, the root note or lowest note of which chord corresponds to an octave above the pedal note desired. Therefore, it is a primary object of this invention to provide an electronic organ keying system which will automatically play in a bass register the root tone of a chord played on a manual keyboard, so that this root note may be utilized to call forth the desired pedal tone, without activating a pedal key.
A prior art system of which applicant is aware (U.S. Pat. No. 3,001,432 to Greif) requires a rather elaborate system of special switches for accomplishing root tone operation. Therefore, it is an object of the present invention to provide an electronic organ having root tone facility which avoids complex switching arrangements. The latter are difficult to adjust at the outset and may be difficult to maintain in proper adjustment after continuous usage.
The purpose of this invention can be accomplished in part, as will be explained hereinafter, by employing a switching arrangement disclosed by Walter Munch, Jr., in a copending application Ser. No. 233,560, assigned to the assignee of the present application, but the Munch switching system is not able to provide a sufficient range of notes for the purposes desired. Therefore, it is a further object of the present invention to provide a root tone system having an extended range of notes.
It is a still further object of this invention to provide a system of the type described which, among other components, necessitates only one additional simple, single-pole, single-throw switch for each key in the range of bass register tones encompassed in a root tone system, in order to incorporate root note facility in a conventional organ.
Yet another object of this invention is to make it possible to select either a normal pedal keying system or an automatic root note system by activation of a simple switch.
These and other objects which will be set forth hereinafter, or will be obvious to one skilled in the art upon reading this specification, will now be described in an exemplary embodiment, reference being made to the accompanying drawing, wherein:
FIG. 1 is a schematic circuit diagram illustrating a preferred embodiment of this invention; and
FIG. 2 is a diagrammatic showing of a "wipe-out" switch system suitable for use in the system of FIG. 1.
Briefly, according to this invention, a note an octave or two octaves below the lowest note of a chord played on the accompaniment manual of an organ is produced by a frequency-dividing flip-flop triggered by a signal selected from the chord notes by use of a preferential or "wipe-out" type of switch, of the type disclosed in the above-mentioned Munch application. This switch is comprised of a series of movable contacts parallel to, and actuated respectively by, playing keys in the lower section of the accompaniment manual. When such a contact is actuated, it makes contact with a transversely arranged, common-contact member anchored at the lower pitch end, so that if another movable contact is actuated by another key, the lower (in pitch) of the two contacts forces the common contact away from the upper (in pitch). Thus, the lower frequency signal is available to trigger the flip-flop. Thereby, when a chord is played, a note corresponding only with the lowest note of the group of keys actuated is sounded.
Usually, the pitch range of a Munch-type switch is only about seven semitones, so if, as is preferable in a roottone system, about an octave and half of semitones is to be included, some means must be provided for extending the range to about 18 or 19 semitones.
The preferred extension system, in accordance with this invention, is to parallel the movable contacts of the Munch-type switch with ordinary make-break key switches actuating diode gates preferentially biased by scaled voltage dividers. By this is meant that the gates, having a common output of the frequency divider, are actuated respectively by a series of voltage dividers graduated in output, arranged so that if two or more gates are keyed concurrently, the lower pitched gate biases off the higher gates, as the former is keyed on by direct current from a common source.
The construction and operation of both phases of this invention will become clear in detail by reference to the accompanying drawings.
FIG. 1, which illustrates the overall electrical circuitry, shows a series of continuously running signal sources labeled (reading from bottom to top) C, C♯, D, D♯ . . . A♯, B, encompassing an octave of the equally tempered scale. The sources are preferably, though not necessarily, corresponding stages in a gamut of 12 transistor frequency dividers of the flip-flop type with square-wave output which preferably are used with conventional keying circuits for supplying organ tones. A point 1, associated with such signal source, indicates where signals would be carried to conventional keying circuits, so that each source provides signal to two sets of gates, one responsive to a conventional manual, and the other, illustrated in FIG. 1, providing tone for root tone generation.
In accordance with the teachings of U.S. Pat. No. 2,233,948 to Kock, tone signals may be passed to collecting and tone-filtering circuits to provide the normal tone output called forth by keys which, as will be explained hereinafter, are used with the present invention. From the sources, C, C♯, D . . ., via coupling capacitors 2, signals are carried to diode gates 4, each composed of a pair of series-connected, solid-state diodes 6 and 8, at the junction of which is provided a bypass impedance composed of resistor 10 and capacitor 12. Voltage dividers for supplying direct current to actuate each gate are comprised of series resistor pairs, as 21 and 23, 25 and 27, 29 and 31 . . ., the tap between each being the output point 14 for feeding each gate 4. The DC keying voltage for these dividers is supplied from a source (not shown) of - 100 volts connected to a terminal 16 via accompaniment keyboard key switches 18. Parallel keying circuits for sources B down to F are shown as "wipe-out" key switches 20, connected one for one to the voltage-divider taps 14. The switches 20 for note F is the lowest one in the accompaniment keyboard, while the key switch 18 for note B is the highest affected key in the keyboard range. The conventionally keyed keyboard will usually extend higher. Switches 20 are arranged as illustrated in FIG. 2 of the present application and are described in detail hereinafter, as well as in the above mentioned application of Walter Munch, Jr.
A source (not shown) of - 16 volts direct current is connected to terminal 22, common to all bypass impedances 10, 12. Bus 24, which provides common output for the gates 4, is connected both to a source (not shown) of -16 volts at terminal 26 via 1.5 megohm resistor 27 and, via capacitor 30, to a trigger amplifier 28. The output of the amplifier 28 is connected via one contact of a single-pole, double-throw selector switch 32 to a frequency-dividing flip-flop system 34, the output of which is carried on to an appropriate electroacoustic output system 36 via tone-color filter 38 and stop switch 40.
To the alternate contact of switch 32 is connected a second bus 42 to which are connected in parallel a series of pedal keyboard switches 44, connected respectively to tone signal sources C C♭C♯, D, . . . B, C.
In operation, if switch 32 is in the lower position, signals keyed by pedal switches 44 pass via bus 42 to the flip-flops 34 where their frequencies are respectively divided by four. The wave form of the signals is modified by the tone-color filter 38 and tone signals are converted to sound in the output system 36, if the stop switch 40 is closed. If, however, the organ player desires to have a low frequency signal occur in the output, when keys are played on the accompaniment manual, the selector switch 32 is thrown to the upper position. If no key switches are actuated, signals from sources C C3, D . . . B, C are blocked from passage to the output bus 24 by virtue of the - 16 volt bias applied to the anodes of the several diodes 6 and 8. If, however, one of the switches 20 is actuated--say the one for note G--the moving contact 23 forces the movable common contact 21 to the left an amount depending upon the travel of the contact 23. Under this condition, the series switch 25 is opened and direct current from the terminal 16 passes via switch contacts 21 and 23 to the tap 14 of the 37, 39 voltage divider for the source G. The diode gate 4 for source G is opened in response to the high negative voltage applied to the cathodes of the diodes 6 and 8 of that diode gate. Signal then appears on bus 24 for passage to the trigger amplifier 28 via coupling capacitor 30, which, incidentally prevents the DC keying voltage from being applied to the amplifier 28. The amplifier 28 output triggers the flip-flop 34 (since switch 32 allows signal passage), supplying signal for modification by tone-color filter 38 and transmittal to the output system 36, when desired, by closure of stop switch 40.
The bypass impedance comprised of resistor 10 and capacitor 12 is selected so that it provides a low impedance relative to the nonconductive impedance of the diodes 6 and 8 but relatively high impedance compared to the conductive impedance of the diodes 6 and 8. Thus, signal feed-through is reduced in the off condition of a gate without appreciable bypass of signal in the on condition.
If the key for a lower note in the scale, say F♯, is actuated, the movable contact 27 forces the common contact member 21 farther to the left and out of contact with contact 23, so the direct current is channeled via contact 27 to the top 14 of voltage divider 41, 43 for source F♯. In a manner similar to that described for note G, an octave-lower F♯ signal will appear in the output system 36. Thus, the series of notes F--B, associated with the key switches 20, will occur on a preferential basis, depending upon the lowest note switch played, if several switches 20 are concurrently actuated. As previously pointed out, about an octave and a half of pedal-equivalent notes are desirable, so when a key switch 18 for a note in the range from C up to B is actuated, an additional octave of signals is provided. If one of the switches 18 is actuated at the same time as one of the switches 20, nothing happens because the series switch 25 is open, and direct current cannot get to the bus 19. If, however, none of the switches 20 is closed, signals can be keyed on by switches 18, because the bus 19 will be charged with direct current via closed series switch 25.
Assuming, however, one switch 18 is already closed and causing signal, say E, to proceed to the output, and then the D♯ switch 18 is closed, whatever DC output is available at tap 14 of the voltage divider 53, 55 for the D♯ gate will be applied to the D♯ gate 4, while direct current available at tap 14 for the divider 49, 51 for the note E will be applied to its gate 4. Both gates are not concurrently opened, however, since the resistors 21, 25, 29 . . . and hence the outputs of several voltage dividers, as 21 and 23, 25 and 27, etc., are scaled, so that the lower note dividers supply a higher bias than the adjacent higher note. For example, if the E voltage divider provides a - 80 volt keying voltage and the D♯ voltage divider provides a - 90 keying voltage, then when the D♯ gate is on, the bus 24 is biased up to - 90 volts, resulting in the right end of the E gate being 10 volts more positive than the left-end gate, so the E gate is biased off and the D♯ signal alone controls the flip-flop 34.
So long as only keys 18 are closed, then one form of preference circuit is operative, i.e. that employing differential bias and described in the last preceding paragraph. If any of switches 20 is activated, control by keys 18 is disabled, and only switches 20 control operation.
Thus, for any combination of notes played in the C up to B octave, the lowest note will always take precedence over the higher ones.
Consequently, the objects set forth above will be provided because in either the "wipe-out" switch 20, 21 range or in the diode gate range, or any combination thereof, the lowest note will always sound automatically, when selector switch 32 is "up".
Turning now to FIG. 2, there is diagrammatically shown a switching arrangement which, while primarily designed for use with manual keyboards in electrical musical instruments is nevertheless adaptable for use with the more extended types of pedal claviers, and which corresponds mechanically and in construction with switches 20 of FIG. 1. A switching arrangement extending over the range from F through B is shown to correspond with the range of switches 20 of FIG. 1. On an insulative base 50 there are fastened a series of wirelike movable switch contacts 52, 54 . . . 64, inclusive. The right-hand end of the switch assembly is shown as broken; but it may be understood that movable contact elements 68 and 70 are representative respectively of the lowest generator in the generator rank and of a generator 12 semitones thereabove. The contact elements 52 to 64 are indicated as connected respectively with generators F to B, inclusive. Contact element 68 will also be connected to generator C, while contact element 70 will be connected to generator B. These connections will be effected via the resistive voltage dividers referred to in FIG. 1, and which are there shown as involving switches 18.
Normally, in instruments employing a rank of continuously operating generators, resistive or gradual-contact switch means are employed for the derivation of oscillations in accordance with the requirements of a musical composition. The use of such gradual-contact switches avoids key thump and key click. Any type of resistive switch may be employed, such as the structures shown in U.S. Pat. No. 2,215,124 in the names of Kock and Jordan, dated Sept. 17, 1940. However, with diode gating the need for resistive switches is obviated. Therefore a preferred switching arrangement for the right-hand portion of the switching assembly of FIG. 2 is a modified form of the type (without the variable resistance feature) set forth and claimed in a copending application in the name of Marion B. Gregory entitled Variable Resistance Key Switch, filed Oct. 29, 1962, Ser. No. 233,529. Thus, the base or panel 50 is shown as carrying an insulative fulcrum bar 72 to control the action of the wirelike movable contacts, and the stationary contact means is a bus or wire 74. The bus 74 corresponds to the bus 19 of FIG. 1. An extension 78 of the bus 74 is shown bent to reach contact element 25 corresponding to contact 25 of FIG. 1, which cooperates with contact arm 21. In FIG. 2 is shown a purely diagrammatic version of a connection 84 between a movable contact member 52 and a playing key 86, it being understood that the several movable switch elements 52, 54, 56 . . . will be connected respectively with playing keys in a manual or clavier, in the manner illustrated for key 86. An insulative sleeve 88 on the contact element 25 prevents the contact 21 making electrical contact with element 25 in the depressed position of any key 86. Upon the depression of any of the movable contact elements 52, 54, 56 . . . by its appropriate playing key, circuit will be made with contact 21, which is shown as extending transversely beneath the movable contact elements 52, 54, 56. . . and - 100 volts is supplied to the appropriate diode gate, FIG. 1. Accordingly, contacts 52, 54, 56. . . correspond with contacts such as 23, 27 of FIG. 1.
The contact 21, which is fastened to the panel 50 at one end, as at 90, not only extends beneath the movable contact elements 52, 54, 56. . . but extends at a small angle to the plane of these contact elements. The free end of the contact 21 will usually lie within bracket-shaped contact 25 which is covered with the antifriction, insulative sleeve 88, thus serving to guide the motion of the wire. Upon depression of any one of the movable contact elements 52, 54, 56. . . by means of its appropriate key, it will be brought out of contact with the contact element 25, and into contact with contact 21. Because of the geometrical relationship between the contact 21 and the contacts 52, 54. . ., if any two contacts of the latter group are simultaneously depressed, the lower pitched one of the two will force the contact 21 away from the higher pitched contact. Thus, the arrangement of FIG. 2, as incorporated into the system of FIG. 1 will always produce a note an octave below the lowest pitched note played on the keyboard, provided the switch 32 of FIG. 1 is in the upper position.
A typical key is illustrated at 80, and another at 91. The key 80, when actuated, closes a gradual resistance switch 81, which causes tone to pass from generator B, lead 1, to tone bus 82, and thence to tone color filters 83, 84, selected by switches 85, 86 for passage to an output circuit 87. The latter may be the same as output 36, or may be separate and independent, but in any event, comprises an amplifier and speaker. Key switch 81 is typical of further key switches 88, 89, 90, which call forth tone from generators A♯, A, G♯ . . . and these keys are the normal and usual accompaniment manual keys of an organ and call forth the normal and usual tones. Key 91 is a similar key but belongs to a note G an octave below that G called forth by a switch 18. Key 91 closes, in addition to its normal tone switch G a , a switch 23, which is one of the preference switches 20.
Accordingly as the accompaniment manual is played, combinations of tones are called forth precisely as they would be in absence of the present invention. The present invention provides for the calling forth of root tones, in addition to the normal and usual tones.
When a single gate 4 is selected, by activation of a chord called forth by switches 18 only, that tone proceeds to flip-flops 34 and controls generation of a tone two octaves below the tone appropriate to the one selected gate. When one or more of switches 20 is actuated, as part of the chord or as the entire chord, a single gate 4 is again selected. But that gate calls forth a note one octave above the note called forth by the actuating key, since in any case the only tone sources available are B, A♯ . . .C. The note then called forth causes, due to flip-flops 34, sounding of a note two octaves low with respect to the gated-through generator, but the latter note is now only one octave below the note required by the actuated key switch 20. This procedure is musically sound, since only 13 notes are normally available in a pedal clavier, but results in 19 keys calling forth a total of 13 pedal tones.
Whereas a "wipeout" switch has been shown for the lower register of notes, it will be understood by one skilled in the art that the preferentially biased, diode gate section may be used alone for a root tone system of extended range. However, the "wipeout" section for the lowest seven notes, as incorporated in the illustrated embodiment, serves only to deactivate the top 12 circuits, in order to allow any note in the lowest seven keys to prevail over any note above the seven keys regardless of pitch.
While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.
Piano players called upon to play electronic organs and novice organ players often have difficulty, while playing on manual keyboards, in concurrently playing pedal notes called for in organ music. Usually such players will be playing a chord on an accompaniment manual, the root note or lowest note of which chord corresponds to an octave above the pedal note desired. Therefore, it is a primary object of this invention to provide an electronic organ keying system which will automatically play in a bass register the root tone of a chord played on a manual keyboard, so that this root note may be utilized to call forth the desired pedal tone, without activating a pedal key.
A prior art system of which applicant is aware (U.S. Pat. No. 3,001,432 to Greif) requires a rather elaborate system of special switches for accomplishing root tone operation. Therefore, it is an object of the present invention to provide an electronic organ having root tone facility which avoids complex switching arrangements. The latter are difficult to adjust at the outset and may be difficult to maintain in proper adjustment after continuous usage.
The purpose of this invention can be accomplished in part, as will be explained hereinafter, by employing a switching arrangement disclosed by Walter Munch, Jr., in a copending application Ser. No. 233,560, assigned to the assignee of the present application, but the Munch switching system is not able to provide a sufficient range of notes for the purposes desired. Therefore, it is a further object of the present invention to provide a root tone system having an extended range of notes.
It is a still further object of this invention to provide a system of the type described which, among other components, necessitates only one additional simple, single-pole, single-throw switch for each key in the range of bass register tones encompassed in a root tone system, in order to incorporate root note facility in a conventional organ.
Yet another object of this invention is to make it possible to select either a normal pedal keying system or an automatic root note system by activation of a simple switch.
These and other objects which will be set forth hereinafter, or will be obvious to one skilled in the art upon reading this specification, will now be described in an exemplary embodiment, reference being made to the accompanying drawing, wherein:
FIG. 1 is a schematic circuit diagram illustrating a preferred embodiment of this invention; and
FIG. 2 is a diagrammatic showing of a "wipe-out" switch system suitable for use in the system of FIG. 1.
Briefly, according to this invention, a note an octave or two octaves below the lowest note of a chord played on the accompaniment manual of an organ is produced by a frequency-dividing flip-flop triggered by a signal selected from the chord notes by use of a preferential or "wipe-out" type of switch, of the type disclosed in the above-mentioned Munch application. This switch is comprised of a series of movable contacts parallel to, and actuated respectively by, playing keys in the lower section of the accompaniment manual. When such a contact is actuated, it makes contact with a transversely arranged, common-contact member anchored at the lower pitch end, so that if another movable contact is actuated by another key, the lower (in pitch) of the two contacts forces the common contact away from the upper (in pitch). Thus, the lower frequency signal is available to trigger the flip-flop. Thereby, when a chord is played, a note corresponding only with the lowest note of the group of keys actuated is sounded.
Usually, the pitch range of a Munch-type switch is only about seven semitones, so if, as is preferable in a roottone system, about an octave and half of semitones is to be included, some means must be provided for extending the range to about 18 or 19 semitones.
The preferred extension system, in accordance with this invention, is to parallel the movable contacts of the Munch-type switch with ordinary make-break key switches actuating diode gates preferentially biased by scaled voltage dividers. By this is meant that the gates, having a common output of the frequency divider, are actuated respectively by a series of voltage dividers graduated in output, arranged so that if two or more gates are keyed concurrently, the lower pitched gate biases off the higher gates, as the former is keyed on by direct current from a common source.
The construction and operation of both phases of this invention will become clear in detail by reference to the accompanying drawings.
FIG. 1, which illustrates the overall electrical circuitry, shows a series of continuously running signal sources labeled (reading from bottom to top) C, C♯, D, D♯ . . . A♯, B, encompassing an octave of the equally tempered scale. The sources are preferably, though not necessarily, corresponding stages in a gamut of 12 transistor frequency dividers of the flip-flop type with square-wave output which preferably are used with conventional keying circuits for supplying organ tones. A point 1, associated with such signal source, indicates where signals would be carried to conventional keying circuits, so that each source provides signal to two sets of gates, one responsive to a conventional manual, and the other, illustrated in FIG. 1, providing tone for root tone generation.
In accordance with the teachings of U.S. Pat. No. 2,233,948 to Kock, tone signals may be passed to collecting and tone-filtering circuits to provide the normal tone output called forth by keys which, as will be explained hereinafter, are used with the present invention. From the sources, C, C♯, D . . ., via coupling capacitors 2, signals are carried to diode gates 4, each composed of a pair of series-connected, solid-state diodes 6 and 8, at the junction of which is provided a bypass impedance composed of resistor 10 and capacitor 12. Voltage dividers for supplying direct current to actuate each gate are comprised of series resistor pairs, as 21 and 23, 25 and 27, 29 and 31 . . ., the tap between each being the output point 14 for feeding each gate 4. The DC keying voltage for these dividers is supplied from a source (not shown) of - 100 volts connected to a terminal 16 via accompaniment keyboard key switches 18. Parallel keying circuits for sources B down to F are shown as "wipe-out" key switches 20, connected one for one to the voltage-divider taps 14. The switches 20 for note F is the lowest one in the accompaniment keyboard, while the key switch 18 for note B is the highest affected key in the keyboard range. The conventionally keyed keyboard will usually extend higher. Switches 20 are arranged as illustrated in FIG. 2 of the present application and are described in detail hereinafter, as well as in the above mentioned application of Walter Munch, Jr.
A source (not shown) of - 16 volts direct current is connected to terminal 22, common to all bypass impedances 10, 12. Bus 24, which provides common output for the gates 4, is connected both to a source (not shown) of -16 volts at terminal 26 via 1.5 megohm resistor 27 and, via capacitor 30, to a trigger amplifier 28. The output of the amplifier 28 is connected via one contact of a single-pole, double-throw selector switch 32 to a frequency-dividing flip-flop system 34, the output of which is carried on to an appropriate electroacoustic output system 36 via tone-color filter 38 and stop switch 40.
To the alternate contact of switch 32 is connected a second bus 42 to which are connected in parallel a series of pedal keyboard switches 44, connected respectively to tone signal sources C C♭C♯, D, . . . B, C.
In operation, if switch 32 is in the lower position, signals keyed by pedal switches 44 pass via bus 42 to the flip-flops 34 where their frequencies are respectively divided by four. The wave form of the signals is modified by the tone-color filter 38 and tone signals are converted to sound in the output system 36, if the stop switch 40 is closed. If, however, the organ player desires to have a low frequency signal occur in the output, when keys are played on the accompaniment manual, the selector switch 32 is thrown to the upper position. If no key switches are actuated, signals from sources C C3, D . . . B, C are blocked from passage to the output bus 24 by virtue of the - 16 volt bias applied to the anodes of the several diodes 6 and 8. If, however, one of the switches 20 is actuated--say the one for note G--the moving contact 23 forces the movable common contact 21 to the left an amount depending upon the travel of the contact 23. Under this condition, the series switch 25 is opened and direct current from the terminal 16 passes via switch contacts 21 and 23 to the tap 14 of the 37, 39 voltage divider for the source G. The diode gate 4 for source G is opened in response to the high negative voltage applied to the cathodes of the diodes 6 and 8 of that diode gate. Signal then appears on bus 24 for passage to the trigger amplifier 28 via coupling capacitor 30, which, incidentally prevents the DC keying voltage from being applied to the amplifier 28. The amplifier 28 output triggers the flip-flop 34 (since switch 32 allows signal passage), supplying signal for modification by tone-color filter 38 and transmittal to the output system 36, when desired, by closure of stop switch 40.
The bypass impedance comprised of resistor 10 and capacitor 12 is selected so that it provides a low impedance relative to the nonconductive impedance of the diodes 6 and 8 but relatively high impedance compared to the conductive impedance of the diodes 6 and 8. Thus, signal feed-through is reduced in the off condition of a gate without appreciable bypass of signal in the on condition.
If the key for a lower note in the scale, say F♯, is actuated, the movable contact 27 forces the common contact member 21 farther to the left and out of contact with contact 23, so the direct current is channeled via contact 27 to the top 14 of voltage divider 41, 43 for source F♯. In a manner similar to that described for note G, an octave-lower F♯ signal will appear in the output system 36. Thus, the series of notes F--B, associated with the key switches 20, will occur on a preferential basis, depending upon the lowest note switch played, if several switches 20 are concurrently actuated. As previously pointed out, about an octave and a half of pedal-equivalent notes are desirable, so when a key switch 18 for a note in the range from C up to B is actuated, an additional octave of signals is provided. If one of the switches 18 is actuated at the same time as one of the switches 20, nothing happens because the series switch 25 is open, and direct current cannot get to the bus 19. If, however, none of the switches 20 is closed, signals can be keyed on by switches 18, because the bus 19 will be charged with direct current via closed series switch 25.
Assuming, however, one switch 18 is already closed and causing signal, say E, to proceed to the output, and then the D♯ switch 18 is closed, whatever DC output is available at tap 14 of the voltage divider 53, 55 for the D♯ gate will be applied to the D♯ gate 4, while direct current available at tap 14 for the divider 49, 51 for the note E will be applied to its gate 4. Both gates are not concurrently opened, however, since the resistors 21, 25, 29 . . . and hence the outputs of several voltage dividers, as 21 and 23, 25 and 27, etc., are scaled, so that the lower note dividers supply a higher bias than the adjacent higher note. For example, if the E voltage divider provides a - 80 volt keying voltage and the D♯ voltage divider provides a - 90 keying voltage, then when the D♯ gate is on, the bus 24 is biased up to - 90 volts, resulting in the right end of the E gate being 10 volts more positive than the left-end gate, so the E gate is biased off and the D♯ signal alone controls the flip-flop 34.
So long as only keys 18 are closed, then one form of preference circuit is operative, i.e. that employing differential bias and described in the last preceding paragraph. If any of switches 20 is activated, control by keys 18 is disabled, and only switches 20 control operation.
Thus, for any combination of notes played in the C up to B octave, the lowest note will always take precedence over the higher ones.
Consequently, the objects set forth above will be provided because in either the "wipe-out" switch 20, 21 range or in the diode gate range, or any combination thereof, the lowest note will always sound automatically, when selector switch 32 is "up".
Turning now to FIG. 2, there is diagrammatically shown a switching arrangement which, while primarily designed for use with manual keyboards in electrical musical instruments is nevertheless adaptable for use with the more extended types of pedal claviers, and which corresponds mechanically and in construction with switches 20 of FIG. 1. A switching arrangement extending over the range from F through B is shown to correspond with the range of switches 20 of FIG. 1. On an insulative base 50 there are fastened a series of wirelike movable switch contacts 52, 54 . . . 64, inclusive. The right-hand end of the switch assembly is shown as broken; but it may be understood that movable contact elements 68 and 70 are representative respectively of the lowest generator in the generator rank and of a generator 12 semitones thereabove. The contact elements 52 to 64 are indicated as connected respectively with generators F to B, inclusive. Contact element 68 will also be connected to generator C, while contact element 70 will be connected to generator B. These connections will be effected via the resistive voltage dividers referred to in FIG. 1, and which are there shown as involving switches 18.
Normally, in instruments employing a rank of continuously operating generators, resistive or gradual-contact switch means are employed for the derivation of oscillations in accordance with the requirements of a musical composition. The use of such gradual-contact switches avoids key thump and key click. Any type of resistive switch may be employed, such as the structures shown in U.S. Pat. No. 2,215,124 in the names of Kock and Jordan, dated Sept. 17, 1940. However, with diode gating the need for resistive switches is obviated. Therefore a preferred switching arrangement for the right-hand portion of the switching assembly of FIG. 2 is a modified form of the type (without the variable resistance feature) set forth and claimed in a copending application in the name of Marion B. Gregory entitled Variable Resistance Key Switch, filed Oct. 29, 1962, Ser. No. 233,529. Thus, the base or panel 50 is shown as carrying an insulative fulcrum bar 72 to control the action of the wirelike movable contacts, and the stationary contact means is a bus or wire 74. The bus 74 corresponds to the bus 19 of FIG. 1. An extension 78 of the bus 74 is shown bent to reach contact element 25 corresponding to contact 25 of FIG. 1, which cooperates with contact arm 21. In FIG. 2 is shown a purely diagrammatic version of a connection 84 between a movable contact member 52 and a playing key 86, it being understood that the several movable switch elements 52, 54, 56 . . . will be connected respectively with playing keys in a manual or clavier, in the manner illustrated for key 86. An insulative sleeve 88 on the contact element 25 prevents the contact 21 making electrical contact with element 25 in the depressed position of any key 86. Upon the depression of any of the movable contact elements 52, 54, 56 . . . by its appropriate playing key, circuit will be made with contact 21, which is shown as extending transversely beneath the movable contact elements 52, 54, 56. . . and - 100 volts is supplied to the appropriate diode gate, FIG. 1. Accordingly, contacts 52, 54, 56. . . correspond with contacts such as 23, 27 of FIG. 1.
The contact 21, which is fastened to the panel 50 at one end, as at 90, not only extends beneath the movable contact elements 52, 54, 56. . . but extends at a small angle to the plane of these contact elements. The free end of the contact 21 will usually lie within bracket-shaped contact 25 which is covered with the antifriction, insulative sleeve 88, thus serving to guide the motion of the wire. Upon depression of any one of the movable contact elements 52, 54, 56. . . by means of its appropriate key, it will be brought out of contact with the contact element 25, and into contact with contact 21. Because of the geometrical relationship between the contact 21 and the contacts 52, 54. . ., if any two contacts of the latter group are simultaneously depressed, the lower pitched one of the two will force the contact 21 away from the higher pitched contact. Thus, the arrangement of FIG. 2, as incorporated into the system of FIG. 1 will always produce a note an octave below the lowest pitched note played on the keyboard, provided the switch 32 of FIG. 1 is in the upper position.
A typical key is illustrated at 80, and another at 91. The key 80, when actuated, closes a gradual resistance switch 81, which causes tone to pass from generator B, lead 1, to tone bus 82, and thence to tone color filters 83, 84, selected by switches 85, 86 for passage to an output circuit 87. The latter may be the same as output 36, or may be separate and independent, but in any event, comprises an amplifier and speaker. Key switch 81 is typical of further key switches 88, 89, 90, which call forth tone from generators A♯, A, G♯ . . . and these keys are the normal and usual accompaniment manual keys of an organ and call forth the normal and usual tones. Key 91 is a similar key but belongs to a note G an octave below that G called forth by a switch 18. Key 91 closes, in addition to its normal tone switch G a , a switch 23, which is one of the preference switches 20.
Accordingly as the accompaniment manual is played, combinations of tones are called forth precisely as they would be in absence of the present invention. The present invention provides for the calling forth of root tones, in addition to the normal and usual tones.
When a single gate 4 is selected, by activation of a chord called forth by switches 18 only, that tone proceeds to flip-flops 34 and controls generation of a tone two octaves below the tone appropriate to the one selected gate. When one or more of switches 20 is actuated, as part of the chord or as the entire chord, a single gate 4 is again selected. But that gate calls forth a note one octave above the note called forth by the actuating key, since in any case the only tone sources available are B, A♯ . . .C. The note then called forth causes, due to flip-flops 34, sounding of a note two octaves low with respect to the gated-through generator, but the latter note is now only one octave below the note required by the actuated key switch 20. This procedure is musically sound, since only 13 notes are normally available in a pedal clavier, but results in 19 keys calling forth a total of 13 pedal tones.
Whereas a "wipeout" switch has been shown for the lower register of notes, it will be understood by one skilled in the art that the preferentially biased, diode gate section may be used alone for a root tone system of extended range. However, the "wipeout" section for the lowest seven notes, as incorporated in the illustrated embodiment, serves only to deactivate the top 12 circuits, in order to allow any note in the lowest seven keys to prevail over any note above the seven keys regardless of pitch.
While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.