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Claims  |
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What is claimed is:
1. A music instrument comprising:
wind music instrument means of the type wherein the emitted acoustic notes
are dependent upon the placement of selection means determining the
instrument air column length;
electronic synthesizer means, including means for generating tones in
dependence upon control signals; and
interface means coupling said wind instrument means to said synthesizer
means, comprising
(i) transducer means adapted to provide analog transducer signals
corresponding to said emitted acoustic notes,
(ii) sensing means for sensing the position of said selection means and
generating a sensing signal indicative of said position, and
(iii) control means responsive to said transducer signals and said sensing
signals for generating a control signal representative of said emitted
acoustic notes, said control signal being coupled to said synthesizer
means to control sounds to be synthesized by said synthesizer.
2. The instrument of claim 1 wherein said transducer means includes a
transducer coupled to the mouthpiece of said wind instrument.
3. The instrument of claim 1 wherein said control means is adapted to
provide control signals for causing said synthesizer means to generate
tones related to said emitted tones.
4. The instrument of claim 3 wherein said control signal contains
information representative of the frequency of the tone to be generated by
said synthesizer means.
5. The instrument of claim 1 wherein said control means includes tone
decoder means responsive to said transducer signals and said sensing
signals, and said decoder means is adapted to sense the presence of
transducer signals within preselected frequency ranges.
6. The instrument of claim 5 wherein said tone decoder means comprises a
plurality of programmable tone decoder circuits each coupled to said
transducer means, and each circuit is adapted to sense the presence of
transducer signals within preselected frequency ranges determined in
dependence upon said sensing signals and generate decoder circuit signals.
7. The instrument of claim 6 wherein said control means includes memory
means for storing digital data indicative of a plurality of tone
frequencies, and wherein said control means is adapted to correlate
particular sensing signals and decoder circuit signals to digital data
stored in said memory means which is indicative of a preselected tone.
8. The instrument of claim 7 wherein said control means further includes
digital to analog converter means for converting stored digital data
representing tone information to analog control signals representing tone
information.
9. The instrument of claim 7 wherein said digital data stored in said
memory means is preselected in accordance with the characteristics of the
particular type of said wind instrument means.
10. The instrument of claim 1 wherein said wind instrument means comprises
a trumpet wherein said selection means comprises three valve means, and
said sensing means comprises means for sensing the position of each valve
means.
11. The instrument of claim 10 wherein said sensing means comprises means
for generating first, second and third sensing signals, each having a
first state when said valve means is in the open position and a second
state when said valve means is in the closed position.
12. The instrument of claim 11 wherein said sensing means comprises first,
second and third magnetic means each adapted to set up a magnetic field,
one of said magnetic means being coupled to each valve piston, and first,
second and third field sensing means, each adapted to indicate the
presence of said magnetic field set up by a corresponding one of said
magnetic means when disposed in proximity to said field sensing means.
13. The instrument of claim 12 wherein each of said field sensing means
comprises switch means having first and second states, wherein the first
state is indicative of the condition wherein the required magnetic field
has not been set up proximate to the switch, and a second state wherein
the required magnetic field has been set up proximate to said sensing
means.
14. A music instrument comprising:
wind music instrument means of the type wherein the emitted notes are
dependent upon the frequency of vibration of the musician's lips and the
placement of selection means determining the instrument air column length;
electronic synthesizer means adapted to generate acoustic tones in
dependence upon control signals; and
interface means coupling said wind instrument means to said synthesizer
means, comprising
(i) transducer means adapted to provide analog transducer signals
corresponding to said emitted acoustic notes;
(ii) means for sensing the position of said selection means and generating
a sensing signal indicative of said position;
(iii) tone decoder means responsive to said transducer signal for detecting
the presence of one or more of a preselected set of tone frequencies, and
adapted to generate decoder signals; and
(iv) control means for generating a control signal in dependence upon said
decoder signals and said sensing signals, said control signal being
coupled to said synthesizer means to control characteristics of signals to
be synthesized by said synthesizer means.
15. The instrument of claim 14 wherein said transducer signal comprises
information indicative of the amplitude of said emitted tones, and said
interface means further comprises amplitude control means adapted to
process said transducer signals and generate an amplitude control signal
for controlling the amplitude of signals to be generated by said
synthesizer means.
16. The instrument of claim 14 further comprising vibrato means allowing
the musician to selectively introduce a vibrato effect on the sound
synthesized by said synthesizer means.
17. The instrument of claim 14 wherein said decoder means is adapted to
sense the presence of transducer signals within preselected frequency
ranges.
18. The instrument of claim 17 wherein said tone decoder means further
includes tuning means responsive to said sensing signals for tuning said
decoder means to select said preselected frequency ranges.
19. The instrument of claim 17 wherein said tone decoder means includes a
plurality of tone decoders, each adapted to sense the presence of
transducer signals within particular frequency ranges determined by said
sensing signals.
20. The instrument of claim 14 wherein said control means is further
adapted to generate a gate signal coupled to said synthesizer means for
controlling the initiation of the attack envelope of sounds to be
generated by said synthesizer.
21. The instrument of claim 20 wherein said gate signal is further adapted
for controlling the initiation of the decay envelope of sounds to be
generated by said synthesizer.
22. Apparatus for interfacing a synthesizer to a wind music instrument of
the type wherein the emitted tone is dependent upon wind applied by the
musician and the placement of selection means determining the instrument
air column length, comprising:
transducer means coupled to said music instrument and adapted to generate
an analog transducer signal indicative of the sound produced by such
instrument;
sensing means for sensing the position of such position means of said
musical instrument and generating binary-valued position signals
representing the position of such selection means;
tone decoder means responsive to said transducer signals for detecting the
presence of one or more of a preselected set of tone frequencies and
arranged to provide binary-valued decoder signals;
central processing unit means (CPU) responsive to said position signals and
said decoder signals for generating a digital control signal
representative of the frequency of tones to be generated by said
synthesizer means; and
digital-to-analog converter means for converting said digital control
signal to an analog signal adapted to control said synthesizer.
23. A music instrument comprising:
wind music instrument means of the type wherein the emitted tone is
dependent upon sounds applied by the musician to a mouthpiece and the
placement of selection means determining the instrument air column length;
electronic synthesizer means, including means for generating tones in
dependence upon control signals; and
interface means coupling said wind instrument means to said synthesizer
means, comprising:
(i) transducer means for generating a transducer signal indicative of
characteristics of the sound applied by the musician, said transducer
means including means coupled to the mouthpiece of said wind instrument
adapted to sense the sound applied to the wind instrument;
(ii) sensing means for sensing the position of said selection means and
generating a sensing signal;
(iii) tone decoder means coupled to said transducer means and said sensing
means, comprising a plurality of tone decoder circuits each coupled to
said transducer means and adapted to sense transducer signals within
predetermined frequency ranges and generate decoder circuit signals; and
(iv) control means for generating a control signal in dependence upon said
transducer signal and said sensing signal, said control signal being
coupled to said synthesizer means to control characteristics of signals to
be synthesized so as to generate tones related to substantially the same
tones as determined by the sounds applied by the musician and positioning
of said selection means, said control means further comprising random
access memory means (RAM) for storing digital data indicative of a
plurality of tone frequencies, said sensing signals and said decoder
circuit signals determining memory addresses for such RAM, and wherein
said control means is adapted to correlate particular sensing signals and
decoder circuit signals to digital data stored in said memory means which
is indicative of a preselected tone.
24. A music instrument comprising:
wind music instrument means of the type wherein the emitted tone is
dependent upon sounds applied by the musician to a mouthpiece and the
placement of selection means determining the instrument air column length;
electronic synthesizer means, including means for generating tones in
dependence upon control signals; and
interface means coupling said wind instrument means to said synthesizer
means, comprising:
(i) transducer means for generating a transducer signal indicative of
characteristics of the sound applied by the musician, said transducer
means including means coupled to the mouthpiece of said wind instrument
adapted to sense the sound applied to the wind instrument;
(ii) sensing means for sensing the position of said selection means and
generating a sensing signal;
(iii) tone decoder means coupled to said transducer means and said sensing
means, comprising a plurality of tone decoder circuits each coupled to
said transducer means and adapted to sense transducer signals within
predetermined frequency ranges and generate decoder circuit signals; and
(iv) control means for generating a control signal in dependence upon said
transducer signals and said sensing signal, said control means comprising:
(a) keyboard simulator means adapted to emulate the status of keys in a
keyboard operated instrument, said control signals comprising sets of
keyboard signals indicating the status of such keys in said simulated
keyboard, said control signals being coupled to said synthesizer means to
control characteristics of signals to be synthesized so as to generate
tones related to substantially the same tones as determined by the exerted
sound and positioning of said selection means, and
(b) memory means for storing digital data indicative of a plurality of tone
frequencies, and
wherein said control means is adapted to correlate particular sensing
signals and decoder circuit signals to digital data stored in said memory
means which is indicative of a preselected tone.
25. A music instrument comprising:
wind instrument means of the type wherein the emitted tone is dependent
upon sounds applied by the musician to a mouthpiece and the placement of
selection means determining the instrument air column length;
electronic synthesizer means adapted to generate acoustic tones in
dependence upon control signals; and
interface means coupling said wind instrument means to said synthesizer
means, comprising
(i) transducer means for generating a transducer signal indicative of the
frequency of the tone which would be generated by said wind instrument in
dependence upon the sounds applied by the musician and upon placement of
said selection means;
(ii) sensing means for sensing the position of said selection means and
generating sensing signals having binary states;
(iii) tone decoder means coupled to said transducer means and said sensing
means and adapted to generate decoder signals, comprising a plurality of
tone decoders, each adapted to sense the presence of transducer signals
within preselected frequency ranges determined by said sensing signals,
and multiplexing means coupled to each decoder for selecting one of said
preselected frequency ranges in dependence upon said sensing signals; and
(iv) control means for generating a control signal in dependence upon said
decoder signals and said sensing signals, said control signal being
coupled to said synthesizer means to control characteristics of signals to
be synthesized by aid synthesizer means.
26. The instrument of claim 25 wherein each of said tone decoders is
adapted to generate a signal having a first state when said decoder senses
the presence of a signal within the preselected frequency range and a
second state when said decoder does not sense the presence of a signal
within the preselected frequency range.
27. The instrument of claim 26 wherein said control means includes memory
means having randomly accessably memory locations in which are stored
digital data corresponding to the notes to be synthesized by said
synthesizer means, and said sensing signals and said tone decoder signals
comprise the address of the memory location of said memory means.
28. The instrument of claim 27 further comprising octave control means
adapted to allow the musician to selectively raise or lower the pitch of
the sound synthesized by said synthesizer means by octave steps about the
nominal pitch defined by said data stored in said memory means.
29. The instrument of claim 27 further comprising pitch means allowing the
musician to selectively vary the pitch of the sound synthesized by said
synthesizer means about the nominal pitch defined by said data stored in
said memory means.
30. The instrument of claim 29 wherein said pitch means further comprises
pressure sensitive transducer means coupled to said wind instrument means
and arranged to provide a pitch signal in dependence upon the amount of
pressure the musician applies to said transducer means.
31. The instrument of claim 30 wherein said pitch means comprises first and
second pitch transducer means adapted to allow the musician to vary the
pitch upwardly or downwardly from said nominal pitch.
32. A music instrument comprising:
wind music instrument means of the type wherein the emitted tone is
dependent upon the sounds applied by the musician to a mouthpiece and the
placement of selection means determining the instrument air column length;
electronic synthesizer means adapted to generate acoustic tones in
dependence upon control signals; and
interface means coupling said wind instrument means to said synthesizer
means, comprising
(i) transducer means for generating a transducer signal indicative of the
frequency of the tone which would be generated by said wind instrument in
dependence upon the applied sounds and the placement of said selection
means;
(ii) means for sensing the position of said selection means and generating
a sensing signal;
(iii) tone decoder means coupled to said transducer mean and sensing means,
and adapted to generate decoder signals;
(iv) control means for generating a control signal in dependence upon said
decoder signals and said sensing signals, said control signal being
coupled to aid synthesizer means to control characteristics of signals to
be synthesized by said synthesizer means; and
(v) vibrato means allowing the musician to selectively introduce a vibrato
effect on the synthesized sound, comprising pressure sensitive transducer
means coupled to said wind instrument means and arranged to provide a
vibrato signal in dependence upon the amount of pressure applied to said
transducer means.
33. The instrument of claim 32 wherein said pressure sensitive transducer
means comprises a pair of bowed metallic plates separated by a pressure
sensitive resistive material.
34. The instrument of claim 32 wherein said vibrato signal is summed with
said control signal to provide a summed control signal to said synthesizer
means.
35. Apparatus for interfacing a wind music instrument of type wherein the
emitted tone is dependent upon sounds applied by the musician to a
mouthpiece and the placement of selection means determining the instrument
air column length comprising:
transducer means coupled to said music instrument and adapted to generate
an electrical transducer signal indicative of characteristics of the sound
produced by such instrument;
sensing means for sensing the position of said selection means of said
musical instrument and generating a digital position signal representing
the position of said selection means;
decoder means coupled to said transducer means and said sensing means, and
arranged to provide digital decoder signals;
central processing unit means (CPU) arranged to receive said position
signal and said digital decoder signals and generate a digital control
signal representative of the frequency of tones to be generated by a
synthesizer means, said CPU including random access memory means (RAM)
wherein digital tone information representing nominal frequencies of tones
to be generated by a synthesizer is stored; and
digital-to-analog converter means for converting said digital control
signal to an analog signal adapted to control a synthesizer.
36. The apparatus of claim 35 wherein said digital tone information stored
in said RAM is adapted to a particular type of such wind instrument.
37. The apparatus of claim 35 wherein said digital position signals and
said decoder signals determine the RAM address at which the digital tone
information corresponding to said position and decoder signals is stored.
38. The apparatus of claim 37 wherein said tone decoder means includes a
plurality of tone decoders each adapted to indicate the presence of a tone
generated by said wind instrument within preselected frequency ranges, and
said CPU is adapted to select that tone decoder indicating the presence of
a tone in the lowest frequency range to select digital tone data stored in
said RAM.
39. Interface apparatus for interfacing an electronic synthesizer to a wind
music instrument of the type wherein the emitted note is dependent upon
the placement of selection means determing the instrument air column
length, comprising:
transducer means adapted to provide an analog transducer signal indicative
of the emitted note;
sensing means for sensing the position of said selection means and adapted
to provide a sensing signal representative of the position of said
selection means;
a plurality of programmable tone decoders responsive to said transducer
signal and said sensing signals, said decoders adapted to be programmed by
said sensing signals to detect the presence of preselected notes in said
transducer signals, and
control means responsive to said tone decoder and adapted to generate
synthesizer control signals,
whereby the operation of said synthesizer is controlled by the playing of
the wind instrument in a substantially normal manner.
40. The invention of claim 39 wherein said tone decoders are adapted to
detect the presence of signal within a predetermined frequency range
centered about said predetermined notes.
41. The invention of claim 40 wherein said tone decoders an adapted so that
said sensing signals select circuit elements which determine said
predetermined frequency ranges.
42. The invention of claim 41 wherein said tone decoders comprise
multiplexing means controlled by said sensing signals, and wherein said
multiplexing means couples a preselected circuit element to said tone
decoder in dependence upon said sensing signals.
43. Apparatus for generating a control signal representative of notes
generated by a wind musical instrument of the type wherein, for each
placement of selection means determining the instrument air column length,
the emitted rate note may comprise the fundamental tone or one of several
overtones, comprising:
transducer means adapted to provide an analog signal corresponding to the
emitted sounds;
sensing means for sensing the position of said selection means and
providing a sensing signal representative of the position of said
selection means;
programmable tone detectors responsive to said analog signal and programmed
by said sensing signals to respectively detect the fundamental note and at
least one of the overtone notes associated with that position of the
selection means, and provide tone decoder signals indicative of such note
detection, and
control means responsive to said tone decoder signals and adapted to
provide a control signal indicative of the note generated by said music
instrument. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to musical apparatus, and, more particularly,
relates to the combination of a wind instrument and an electronic music
synthesizer.
2. Description of the Prior Art
Due in part to the relatively high cost of providing an orchestra or group
of performing musicians, the music synthesizer has become an important
music instrument. For example, it is known that music accompanying a
television program is quite often generated by a musician playing a music
synthesizer to obviate the expense of a complete orchestra. Many
synthesizers are adapted for keyboard operation, requiring the musician be
trained as a keyboard musician. This is a limiting feature since the
expertise of many musicians is limited to other non-keyboard musical
instruments. Such musicians would be unable to skillfully utilize a
keyboard synthesizer without additional training.
It is, therefore, desirable to provide a means to allow the musician to
control the synthesizer in a manner which utilizes the musician's existing
expertise in playing a musical instrument, and which does not require
extensive retraining in keyboard instruments. One of the inventors of the
present invention has addressed this need with respect to musical
instruments having substantially a one-to-one relationship between each
key and an associated note. U.S. Pat. No. 4,342,244 discloses a music
apparatus which allows a musician to control the output of a music
synthesizer while playing his own music instrument, e.g. a saxaphone, in a
normal manner. This music apparatus does not solve the problem associated
with music instruments such as the trumpet wherein there is not a
substantially one-to-one relationship between the setting of the
instrument keys or valves and the associated note. With such instruments
the range of the note produced can also be varied by the musician varying
his lip configuration on the instrument mouthpiece. Thus, with a given
valve selection, the musician may produce not only the primary note but
may produce one or more overtones of the primary note by varying his lip
configuration.
U.S. Pat. No. 3,938,419, issued to De Rosa, discloses an attempt to resolve
this problem. De Rosa discloses a switch arrangement which detects the
positions of the trumpet valves and an operator controlled switch which
together define the particular note being produced by the instrument. An
important drawback to the De Rosa instrument is that it does not allow the
musician to control the synthesizer by playing the trumpet in a normal
manner. Instead, the musician must not only manipulate the keys while
blowing into the instrument, but must also manipulate a note selection
switch which is foreign to the trumpet. This additional switch not only
increases the difficulty of operating the instrument, but also requires
very rapid manipulation of the selection switch when the musician
transitions from one note range to another.
It is accordingly one object of the present invention to provide an
interface apparatus which allows a musician of an instrument such as a
trumpet, tuba, French horn, trombone or the like, to control the operation
of a synthesizer by playing the instrument in a normal manner.
It is another object of the present invention to provide a novel music
apparatus comprising the combination of a wind instrument operated by the
selection of means determining the air column length and the applied wind
pressure, an electronic music synthesizer and an interface circuit,
whereby the musician controls the operation of the synthesizer by playing
the wind instrument in a normal manner.
It is yet another object of the present invention to provide an improved
interface apparatus which not only senses the valve positions of the
instrument but also the pitch and loudness of the note being played by the
musician.
It is a further object of the invention to provide an interface apparatus
utilizing improved means of sensing the valve positions.
It is yet another object of the present invention to provide a novel
trumpet-to-synthesizer interface apparatus which comprises musician
control means allowing the musician to produce vibrato effects or pitch
variations in the synthesized sounds.
These and other objects and advantages are achieved by the present
invention as will be apparent from the following description of the
invention.
SUMMARY OF THE INVENTION
The present invention is a novel musical instrument comprising a wind
instrument of the type wherein the note generated is dependent upon the
instrument air column length and the musician's lip pressure, a music
synthesizer and an interface apparatus. The interface apparatus comprises
position sensing means for generating a sensing signal indicative of the
instrument air column length, and transducer means for generating a
transducer signal indicative of characteristics of the wind pressure being
applied by the musician. The interface apparatus further comprises control
means arranged to receive the sensing signal and transducer signal. The
controller is adapted to process the sensing and transducer signals, and
from this information, as well as characteristic information defined by
the particular type of wind instrument being employed, generate a
synthesizer control signal to control characteristics of sounds to be
synthesized by the electronic synthesizer.
Means are also provided to easily allow the musician to produce vibrato
effects or vary the pitch of the synthesized sounds. The invention is
readily adapted to control various types of synthesizers, such as those
having a voltage controlled oscillator for controlling the frequency of
synthesized sounds, or to synthesizers controlled by a keyboard matrix.
Other features and improvements are disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the preferred embodiment of the present
invention.
FIG. 2 is a schematic diagram of circuit elements contained on the valve
sensing circuit board of the preferred embodiment.
FIG. 3 is a block/schematic drawing illustrating the arrangement of the
valve sensing elements utilized in the preferred embodiment.
FIG. 4 is a schematic drawing illustrating the tone decoders of the
preferred embodiment.
FIG. 5 is a schematic drawing of a typical tone decoder circuit as used in
the preferred embodiment.
FIG. 6 is a schematic drawing illustrating the manual vibrato and pitch
alteration circuit of the preferred embodiment.
FIG. 7 is a schematic drawing of the loudness detection circuit of the
preferred embodiment.
FIG. 8 is a program flow chart illustrating one aspect of the operation of
the controller of the preferred embodiment.
FIG. 9 is a block diagram illustrating the keyboard simulator circuit for
an alternate embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention comrprises a novel music apparatus. The following
description of the invention is provided to enable any person skilled in
the art to make and use the invention and sets forth the best modes
contemplated by the inventors of carrying out their invention. Various
modifications, however, to the disclosed embodiments will be readily
apparent to those skilled in the art, and the generic principles defined
herein may be applied to those modifications. Thus, the present invention
is not intended to be limited to the embodiments shown, but is to be
accorded the widest scope consistent with the principles and novel
features disclosed herein.
The music apparatus of the present invention includes a novel apparatus by
which a musician may control the output of a music synthesizer while
playing his own wind instrument in a normal manner. The invention is a
substantial improvement over the invention disclosed in U.S. Pat. No.
4,342,244, which was adapted to music instruments having a substantially
one-to-one relationship between the emitted acoustic tone and the
positions of the tone control elements, as in the saxaphone and flute
families, the bass clarinets, bassoons, and pianos.
Certain brass instruments such as the trumpet, valve trombone, euphonium,
tuba and the slide trombone depart from this one-to-one relationship in
that the musician achieves a chromatic scale of more than three octaves
through the manipulation of three valves (sometimes four) by varying the
lip pressure on the mouthpiece to produce different tones on the natural
overtone note series associated with any air column length, i.e., any
given valve combination. In the case of the slide trombone, the musician
uses a combination of seven basic slide positions and varying lip
pressure.
The music apparatus of the present invention includes a novel
trumpet-to-synthesizer interface which provides a signal indicative of the
particular emitted tone through a novel combination which includes the
following elements: (1) minature samarium-cobalt magnets, coupled with
Hall effect IC sensors to detect the valve (or slide) position; (2) CMOS
1-OF-8 integrated circuit multiplexer chips to sort out the valve
combinations, and provide a corresponding digital output; and (3)
phase-locked loop IC decoders to detect the position of a tone on the
natural overtone series of any given valve (or slide) combination. In the
prior art described above, U.S. Pat. No. 3,938,419, an attempt to address
the first two elements was made through the use of electromechanical
switches and a matrix of relays. However, with regard to the third
element, the only way the player could convey to the synthesizer which
tone on the natural overtone series he was playing for a given valve
combination on a trumpet, for example, was by concurrently manipulating a
cumbersome rotary switch.
Referring now to FIG. 1, a block diagram of the preferred embodiment is
disclosed. This embodiment utilizes a B flat trumpted 10 having three
valves, 12, 14 and 16. Block 100 depicts an enclosure which contains
circuit elements inter alia for sensing the position of each trumpet
valve. A mouthpiece transducer 150 is coupled to the mouthpiece of the
trumpet 10. The electrical analog output from transducer 150 is coupled to
enclosure 100.
Phantom line 200 encloses circuitry for encoding the valve position
information. Circuit 200 comprises eight CMOS 4051 integrated circuits,
which each comprise an eight-channel analog multiplexer/demultiplexer.
Circuit 200 further comprises eight LM 567 tone decoder integrated circuit
chips which are collectively used to determine the position of a
particular tone on the natural overtone series for any given valve
combination.
CPU 300 is coupled to circuit 200 and in the preferred embodiment comprises
a Zilog Z80 microprocessor. The CPU monitors the valve sensors and tone
decoders and correlates information generated by these elements with a
look-up table or algorithm to determine which note is played. CPU 300 then
generates a digital output word which is provided to digital to analog
converter 400 for generating a control voltage, which is amplified by
amplifier 450 and delivered to the synthesizer 500.
The invention is adaptable for use with virtually any synthesizer on the
market today. Typical synthesizers utilize a voltage controlled oscillator
to select the particular frequency to be synthesized. Thus, the control
voltage comprising the output of the digital-to-analog converter 400 in
turn defines the frequency to be synthesized. The synthesizer used in
connection with the preferred embodiment is an Oberheim OBX synthesizer.
Digital to analog converter 400 in the preferred embodiment is a 10 bit
unit, using the six most significant bits. Converter 400 operates in 1/12
volt steps, so that a one octave range is equivalent to a converter
voltage differential of one volt.
Alternatively, the output of the CPU could be used in conjunction with a
keyboard matrix simulator 600 for ready use with an existing keyboard
synthesizer. Still another alternative is to adapt the CPU to the industry
standard Musical Instrument Digital Interface ("MIDI"), which provides a
standard interface for coupling synthesizers to one another or to a
controller.
Referring now to FIG. 2, a schematic diagram of the circuitry in enclosure
100, which is physically attached to the trumpet 10, is disclosed. In the
preferred embodiment, enclosure 100 is secured to the trumpet by bolts
(not shown) which fit through openings between the trumpet valves and are
secured by a retainer and wing nuts on the opposite side of the trumpet.
This arrangement allows the enclosure to be readily removed by the
musician in the event that the trumpet is to be used without the
synthesizer and interface circuit. Other arrangements for coupling
enclosure 100 and the circuity it carries to the trumpet will be readily
apparent to those skilled in the art. The circuitry in enclosure 100 is
coupled to the encode/decode circuitry 200 shown in FIG. 1 through a nine
pin connector and cable 190.
Terminal 155 is coupled to the signal output of transducer 150 fitted to
the trumpet mouthpiece. In the preferred embodiment, a transducer marketed
by Barcus-Berry, Inc., Musical Instruments Division, 5782 East Second
Street, Long Beach, Calif., 90803, is used. This transducer is a high
impedance device, and a high-to-low impedance converter is provided to
match the impedance levels. The transducer output signal is an analog
signal representative of the audio signal emitted by the trumpet.
Still referring to FIG. 2, device 110 comprises a JFET transistor which
couples the transducer output to the remainder of the circuit, acting as a
high-to-low impedance converter. Device 110 may comprise, for example, a
2N3321 or 2N3819 JFET transistor. The drain terminal 107 of transistor 110
is coupled through 1 Kohm resistor 102 to pin 1 of connector 190, for
connection to the +15 volt supply voltage. Terminal 107 is also coupled
through 8 microfarad capacitor 114 to ground. The source terminal 108 of
the transistor 110 is coupled through 0.2 microfarad capacitance to
terminal 9 of connector 190, and comprises the analog audio output to be
coupled to the tone decoders. Source terminal 108 is also coupled to
ground by 22 Kohm resistor 116.
Circuitry 105 includes three "Hall effect" digital sensor switches 125, 130
and 135, one for each trumpet valve. Each sensor is cooperatively mounted
in enclosure 100 such that the sensor is mounted adjacent the respective
valve at the end of travel for the valve piston in its closed
configuration. As will be described more fully, minature samarium-cobalt
permanent magnets are bonded to the end of each valve piston. Thus, when
the valve piston is depressed to the closed position, the magnet is
disposed in sufficiently close proximity to the sensor to trigger the
switch.
The "Hall effect" sensor switches used in the preferred embodiment are
distributed by the Radio Shack division of Tandy Corporation, as catalog
part number 276-1646. These switches are magnetically-activated electronic
switches utilizing the Hall effect for sensing a magnetic field. Each chip
is understood to consist of a silicon Hall generator, amplifier, trigger
and output stage integrated with its own voltage regulator onto a
monolithic silicon chip. The output transistor is normally "off" when the
magnetic field perpendicular to the surface of the chip is below the
threshold point. When the field exceeds the threshold, the output
transistor switches "on." The output transistor switches "off" when the
magnetic field is reduced below the release point which is less than the
operate point. This hystersis characteristic provides for unambiguous or
non-oscillatory switching in the event of changes in the magnetic field.
The nominal operative point of the device is 300 gauss, and a nominal
release point is 210 gauss.
The switched outputs 126, 131 an 136 of switches 125, 130 and 135 are
respectively coupled to pins 3, 4 and 5 of connector 190. The Hall effect
sensors are arranged such that in the normal "off" position, a high output
signal, at 15 volts, is provided. In the switched "on" position, a low
signal, at ground, is provided. Thus, switches 125, 130 an 135 are
nominally open, when the respective valves are open, and the switched
outputs 126, 131 and 136 have a nominal high, +15 volt, state. When a
valve is closed, the respective output signal switches to the low state,
at ground.
In the preferred embodiment, box 100 comprises an alumimum enclosure,
although other non-magnetic materials, e.g., a thermoplastic material,
could readily be substituted.
Referring now to FIG. 3, the spatial relationship between the magnets
affixed to the valve piston and the Hall effect sensors is illustrated.
Magnets 50, 52 and 54 are respectively affixed to the bottom of the valve
pistons 13, 15 and 17. The magnets used in the preferred embodiment
comprise miniature samarium cobalt magnets and are affixed to the pistons
by glue. Of course, other magnets and means for fixing the magnets in
place are suitable for the purpose and will be readily apparent to those
skilled in the art.
Sensors 125, 130 and 135 are mounted in enclosure 100 adajacent the lower
end of travel of pistons 13, 15 and 17 respectively. Openings are formed
in enclosure 100 in the areas between sensor 125 valve 12, sensor 130 and
valve 14, and sensor 135 and valve 16. These openings are formed so that
the metallic material forming enclosure 100 does not shield the magnetic
field of the permanent magnets from the Hall effect sensors.
Referring now to FIG. 5, an exemplary tone decoder circuit is illustrated
in schematic form. Chip 700 comprises a LM 567 integrated circuit chip.
The LM 567 chip is manufactured, for example, by the Signetics Corporation
and comprises a tone and frequency decoder. The operation of this chip is
known to those skilled in the art and need not be described in great
detail. Briefly, the chip may be operated as a very narrowband detector to
detect the presence of a signal in a relatively narrow frequency range. By
appropriate selection of the biasing parameters, a resistance and
capacitance, the decoder may be tuned to the center of a relatively narrow
bandwidth. The bandwidth may be sufficiently narrow to substantially
select a single musical note.
The center frequency selection resistance is applied across terminals 5 and
6 of chip 700. The center frequency selection capacitance is coupled from
terminal 6 of chip 700 to ground. In the preferred embodiment the
selection resistance is selected in multiplexed fashion by operation of
the selector chips, e.g., chip 205. Thus, node A is coupled to terminal 3
of the respective multiplexer chip. Each of the nodes B is coupled to the
appropriate "Y.sub.13 " terminal 1, 2, 4, 5, 12, 13, 14 or 15.
The multiplexing occurs in the following manner. A plurality of resistors,
for example, resistances 730, 740, 750, 760, 770, 780 and 790, are coupled
to terminal 5 of chip 700. Each resistance is coupled to a particular one
of the addressable terminals of a CD 4051 selector chip. The status of the
Hall effect switch outputs 126, 131, 136 determines which one of the
addressable terminals is selected, and, therefore, also the particular
decoder tuning resistance. Thus, each decoder may be selectively tuned to
one of eight possible center frequency selection resistances.
Resistor 730 in FIG. 5 depicts the tuning resistance value for the trumpet
open valve configuration, or the first slide position of a trombone.
Resistor 740 depicts the tuning resistance value for the valve
configuration wherein only the second valve 14 is closed, or alternatively
the second slide position.
Resistor 750 represents the timing resistance value for the valve
configuration wherein only the first valve 12 is closed, or the third
slide position. Resistor 760 represents the timing resistance value for
the configuration in which only valves 12 and 14 are closed, or the
trombone fourth slide position. Resistor 770 represents the timing
resistance value for the configuration in which only valves 14 and 16 are
closed, or the fifth slide position. Resistor 780 represents the timing
resistance value for the configuration in which only valves 12 and 16 are
closed, or the sixth slide position. Resistor 790 represents the timing
resistance value for the configuration where all three valves are closed,
or the seventh trombone slide position.
Terminal 8 of chip 700 comprises its primary output, the uncommitted output
transistor collector. When an in-band input signal is present, the
transistor saturates, the collector voltage being less than one volt.
Terminal 8 is coupled to output node 795. LED 797 and 470 ohm resistor 798
are coupled in series between node 795 and the +5 volt supply to provide a
visual indication that a tone in the selected passband is present. Switch
712 may be closed to manually cause a "tone present" indication; this
switch is present only on first tone decoder 205 in the preferred
embodiment. Other biasing element values used in the preferred embodiment
comprises 2.2 microfarad capacitor 701, 1 microfarad capacitor 702, 0.1
microfarad capacitors 704 and 706, and 100 Kohm potentiometer 703. The
audio input from the transducer 150 is coupled through pin 1 of connector
190 to terminal 3 of chip 700 through resistance 703 and capacitor 704.
As will be discussed below, in the preferred embodiment each decoder is not
set up to decode tones for all possible configurations of the valves. In
the preferred embodiment only thirty-eight notes are decoded.
The center frequency F.sub.o of the passband of the LM 567 chip is selected
by the formula Fo=1.1/RC, where R is the resistance connected between
terminals 5 and 6 of the chip, and C is the capacitance coupl | | |
