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Claims  |
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We claim:
1. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck and a body, in which the neck carries a
plurality of pitch strings, and pitch sensing means for electrically
sensing the location of depression of the strings by a player, and the
body carries key-operated switches corresponding to the strings
respectively for initiating notes of a pitch defined by the output of the
pitch sensing means.
2. An instrument according to claim 1, in which the pitch strings make
electrical contact with frets on the neck to define the selected note.
3. An instrument according to claim 1, in which the body additionally
carries trigger strings, one for each pitch string respectively, which can
be struck to initiate a note.
4. An instrument according to claim 1, including a master trigger switch
for initiating notes in respect of all the strings simultaneously.
5. An instrument according to claim 1, including interlock means enabling
simultaneous operation of some of the key-operated switches.
6. An instrument according to claim 1, including means actuable in an
alternative mode of operation for automatically triggering a note in
response to depression of a string.
7. An instrument according to claim 3, including means actuable in a
further mode of operation for automatically triggering a note in response
to depression of a string.
8. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck and a body, in which the neck carries a
plurality of pitch strings and means for electrically sensing the location
of depression of the strings by a player, and for automatically triggering
a note in response to depression of a string, in which the body carries
alternative triggering means, and switch means for selectively disabling
automatic triggering.
9. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a plurality of strings, and touch sensor means
for detecting touching of the strings by a player, in which the touch
sensor means comprises a driver circuit for applying to the strings
selectively a low frequency a.c. signal component together with a d.c.
component, and detecting means for detecting a variation in response to
either of the said components to indicate touching of the string.
10. An electronic musical instrument configured to represent a guitar-like
instrument and comprising separate pitch determining means on the neck of
the instrument and triggering means on the body of the instrument, in
which the triggering means comprises a manually-actuable triggering
member, a magnet, and a Hall effect device, the magnet being in physical
connection with the triggering member such that movement of the triggering
member causes the magnet to move, and the Hall effect device detects
movement of the magnet to provide a trigger output signal to initiate
triggering.
11. An instrument according to claim 9, including circuit means connected
to the output of the Hall effect device for providing a first signal
indicative of the timing of the-manual actuation of the triggering member,
and a second signal indicative of the rate or amplitude of the movement of
the triggering member.
12. An electronic muscial instrument configured to represent an guitar-like
instrument and comprising a neck and a body, in which the neck carries a
plurality of pitch strings, and including circuit means for generating
electrical output signals representative of the pitches determined by the
pitch strings, sensor coils in the neck for sensing forced lateral
deflecton of the strings from their undeflected positions and producing an
output in response thereto, and means connected to receive the output of
the sensor coils to control the circuit means to vary the pitches
represented by the output signals.
13. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck and a body, in which the neck carries a
plurality of pitch-determining pitch strings and means for electrically
sensing the location of depression of the strings by a player, and in
which the body carries a vibrato arm, and includes means for generating a
varying electrical output signal in dependence upon movement of the
vibrato arm, and means for varying the pitch of the instrument about that
set by the pitch strings in dependence on the output signal, the signal
generating means comprising a Hall effect device and a magnet co-operating
with the Hall effect device, the magnet being in physical connection with
the vibrato arm such that movement of the triggering member causes the
magnet to move, with the Hall effect device for detecting movement of the
magnet to provide said electrical output signal.
14. An electronic musical instrument configured to represent a guitar and
comprising a neck and a body, in which the neck carries a plurality of
substantially parallel pitch strings which overlie a series of frets, and
the body carries a corresponding number of substantially parallel trigger
strings, and in which the two sets of strings lie at an angle to each
other.
15. An instrument according to claim 14, in which the angle lies between 5
degrees and 45 degrees.
16. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck carrying a plurality of pitch strings, a
plurality of parallel conductive fret means extending across the neck
transversely of the pitch strings, and means connected to the pitch
strings and the fret means to sense the location of depression of the
strings by a player, in which each fret means comprises a plurality of
sections at least equal to the number of strings forming each fret, each
string being capable of lateral deflection by the player to cause pitch
variation, and to contact a fret section adjacent to that which the string
overlies, the sections of each fret means being coupled to a common output
for that fret means through respective electrical isolating means between
each section of the fret means and the common output, whereby electrical
isolation between different pitch strings is maintained on forced lateral
deflection of the strings.
17. An instrument according to claim 16, in which said electrical isolating
means comprise diodes.
18. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck carrying a plurality of pitch strings,
conductive fret means, and means connected to the pitch strings and the
fret means for sensing the location of depression of the strings by a
player, in which each fret means comprises a plurality of sections at
least equal to the number of strings forming each fret, and in which each
fret means comprises fret sections under each undeflected string and fret
sections which are only contacted when a string is laterally deflected.
19. An electronic musical instrument, configured to represent a guitar-like
instrument and comprising a neck carrying a plurality of pitch strings,
conductive fret means, and means connected to the pitch strings and the
fret means for sensing the location of depression of the strings by a
player, in which each fret means comprises a plurality of sections at
least equal to the number of strings forming each fret, and in which
adjacent fret sections closely abut and the end faces of the sections are
not parallel to the length of the strings.
20. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck carrying a plurality of pitch strings and
means for electrically sensing the location of depression of the strings
by a player, further comprising means for selectively individually
resetting the musical value of the note which corresponds to the free
undepressed strings.
21. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck carrying a plurality of pitch strings and
means for electrically sensing the location of depression of the strings
by a player, further comprising means for storing selected values for the
free strings and for recalling selected ones of the stored values.
22. An electronic musical instrument configured to represent a guitar-like
instrument and comprisng a neck carrying a plurality of pitch strings and
means for electrically sensing the location of depression of the strings
by a player, further comprising means for electrically simulating the
effect of a capo in resetting the lowermost notes of each string to a
selected lowest pitch different from the free value pitch for the string.
23. An electronic musical instrument configured to represent a guitar-like
instrument and comprising a neck and a body, in which the neck carried a
plurality of pitch strings and means for electrically sensing the location
of depression of the strings by a player, and the body carries triggering
means for initiating the selected notes, further comprising
manually-operable means for selectively varying the decay rate of the
selected notes, said instrument further including touch sensor means for
sensing when the strings are touched by a player, and for switching
between preselected decay rates. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates to electronic music making and in particular to
electronic musical instruments.
DESCRIPTION OF THE PRIOR ART
The prior art can principally be divided into two groups, namely electric
fingerboard stringed instruments, and synthesisers. The expression
`fingerboard stringed instruments` is here used to denote instruments in
which the strings are struck, plucked or bowed without the use of a
keyboard, and the note played is determined by shortening the effective
length of the string by the amount necessary to cause it to vibrate at the
desired pitch. It is first desirable to consider such fingerboard stringed
instruments generally.
1. Stringed Instruments
There are many forms of "guitar-like" or plucked, stringed instruments,
from the Oriental Koto and the Indian Sitar, to the American Banjo and the
Spanish Guitar. Although there are marked differences in the sizes,
materials used, forms of construction and numbers of strings employed on
these instruments, one common feature of the guitar family of stringed
instruments is that the musician can produce a variety of notes on each
string by altering that effective length of the string. This is done by
pressing the string down on the face of the neck of the instrument (this
face is called the fretboard on a guitar).
This feature makes this family of stringed instruments stand apart from
those of the keyboard family (piano, harpsichord, clavichord etc), in
which each note produced has its own individual key on the keyboard with
its own individual string.
The violin family (including the viola, cello and string bass), has a
similar pitch control arrangement to the guitar family in that each string
produces a variety of pitches according to the length of the string, but
the dynamic performance of a note is usually started and sustained by
bowing the string.
In contrast, the guitar family of instruments is dynamically triggered by
plucking the string. This may be done with the bare fingers, or it may be
done with individual finger picks, or a plectrum or quill. In each case
the result is similar. The string is displaced from its state of
equilibrium by the plucking device prior to the start of the note, and the
string is released at the moment the note is required to start. The string
will then vibrate, producing a musical note. The amplitude of the note
that the string produces now goes through a dynamic cycle of `Attack` and
`Decay` which will depend on the extent to which the string was originally
displaced, and also on the inherent acoustic characteristics of the
particular instrument.
Unlike a violin, the duration that the note remains audible or "sustains"
is dependent on these last two factors, whereas a violin note can be
sustained for as long as the player chooses by bowing the string.
The natural decay of the plucked string of a guitar can be brought to a
premature end by damping the vibrating string with the hand. This can
effectively make the note "switch off" if the musician desires.
This fact limits the playing style of the guitar player. An open string,
that is a string which is free-standing in its natural state of mechanical
equilibrium--i.e. it has not had its musical note value modified by the
musician's finger "stopping" it on the fretboard and thereby shortening
its effective length, may be plucked, and will continue on its natural
attack and decay cycle in a free standing state, regardless of the
behaviour of the guitar player's hands, so long as he does not interrupt
this cycle by damping the vibrating open string.
However, when a guitar player modifies the note produced by the string by
holding it down on the fretboard and shortening the effective string
length, he can start the dynamic cycle by plucking it, but he has to keep
the string pressed down on the fretboard with his finger in order to
maintain the natural attack and decay cycle of that string. If he does
take his finger off the string, the note will prematurely switch off, or
damp.
The surface of the neck of a guitar is divided by lateral wires, or frets,
set perpendicular to the strings. This divides the physical length of each
string into exact and successive semitone values. As the player runs the
string up the fretboard with his finger, the pitch produced by the string
will rise in ascending chromatic intervals as the length of the string
shortens by succeeding ratios of 1:12th root of 2.
2. Electric Stringed Instruments
Electric instruments (such as electric guitars, violins, basses, or
mandolins) generate analogue audio frequency voltages which are modified
and reproduced via a special amplifier. (There are some hybrid devices
which produce sounds in both an electronic and a non electronic fashion
simultaneously. Such instruments are usually known as semi-acoustic
instruments.)
The strings of these electric instruments are made of magnetic material,
and vibrate when excited in the same way as a non-electric instrument.
Mounted underneath the strings is a pick-up in the form of an
electro-magnetic coil. As the strings vibrate above the coil, they vary
the magnetic flux density of the field around the coil, inducing an
alternating current in the coil related to the vibrations of the strings.
The varying voltage from the output of the coil is fed to an amplifier and
then to a loudspeaker to produce the sound.
Electric instruments use the same method of pitch control and dynamic
triggering/attack and decay as their non-electric counterparts. The design
of the electric versions of instruments, particularly their necks, share
the same mechanical and acoustic constraints as non-electric instruments.
3. Synthesisers
The musical instruments which are commonly known as synthesisers (or
`synths`) originated with the advent of the Voltage Controlled Oscillator
(VCO). In early analogue versions, the pitch and the dynamic parameters of
a musical instrument are controlled by two completely different elements.
The Voltage Controlled Oscillator generates the preset pitch of the musical
note to be produced. This is controlled by feeding an analogue voltage to
the VCO control input related to the pitch desired at the VCO output. The
dynamic performance of the musical note is controlled by following the
output of the VCO with a Voltage Controlled Amplifier (VCA). By triggering
the control input of the VCA with a voltage which goes through a cycle of
rise time and fall time (`Attack` and `Decay`), the dynamic performance of
the note heard (or envelope shape) can be modified by altering the attack
and decay characteristics of the control input "trigger" signal to the
VCA. Countless variations in signal processing can produce a wide range of
subtleties in shaping the sounds produced, but all early analogue synths
use this basic control system.
From the beginning such synthesisers or electronic organs have adopted a
piano-style keyboard which is familiar to a large number of musicians and
is a convenient way of inputting information as to the note(s) desired to
be played. Each key on an early synth keyboard produces a unique analogue
voltage to be fed to the VCO control input. This control voltage is
related to the pitch to be produced by the VCO when each particular key is
pressed.
When a key is pressed, the specially shaped control voltage signal is
"triggered" at the corresponding VCA input, producing the dynamic attack
and decay of the note (or envelope shape).
Subsequent synthesisers have made use of unique digital codes rather than
analogue voltages for each key of the keyboard. In this form, the basic
pitch information can easily be manipulated like data in a computer, and
when the code has been through all the desired processing, it is converted
by a digital-to-analogue converter (DAC) into the correct analogue voltage
to set the pitch of the associated VCO.
Some of these later synthesisers also employ keyboards which produce not
only the dynamic trigger signals, but also velocity and pressure sensing
circuits which produce signals proportional to how fast a player hits the
keys, and with how much pressure he holds the keys down. These signals can
be used via processing circuitry, to modify a variety of parameters,
including the loudness of the notes and the harmonic content of the notes.
This makes the instrument far more musically expressive.
The latest generation of synthesisers are basically computers with special
software which makes them into musical instruments. The waveform, rather
than being split into pitch and envelope shape parameters with VCO's and
VCA's, is defined very accurately in digital form, and stored in memory as
wavetables or families of wavetables. The structure of the digital
waveforms can be defined in a variety of ways according to the design of
the software. Control parameters can be put in from a keyboard, waveforms
or time dependent spectral information can be drawn with a light pen on a
video terminal, and natural sounds can be sampled via a microphone and a
DAC to form a particular wavetable. Once initially defined in memory, the
original signal may be further modified according to the desires of the
musician, and the inventiveness of the software designer.
These instruments are musically controlled in real-time, again with the use
of a piano-style keyboard, which produces the digital pitch control codes,
trigger signals, and sometimes velocity and pressure sensing.
To date, only synthesisers which are controlled by a piano-style keyboard
have had any significant success as real-time musical instruments.
4. Guitar Synthesisers
Then there a number of devices called guitar synthesisers which incorporate
features of an electric stringed instrument and of a synthesiser. These
devices are basically electric guitars which use additional
Pitch-to-Voltage Convertors which analyse the frequency and amplitude of
the electro-magnetic oscillations in the pick-up coil, and attempt to
convert them into accurate control signals to drive the pitch and trigger
parameters of a synthesiser.
The most difficult problem associated with such a system is the harmonic
content of the original signal in the guitar pick-up. Very often the
harmonic content is high enough to make the pitch-to-voltage convertor
prone to error, producing some very unpredicatable results. Also, the
guitar player very often wishes to play chords, rather than monophonic
melodies, and this adds crosstalk problems to a guitar-synth system which
is capable of polyphony. In fact most guitar synths are only monophonic.
Furthermore, the triggering system is very basic; when the amplitude of
the coil signal exceeds a preset threshold, the envelope shape cycle is
triggered, and as long as the amplitude remains above that threshold, the
note can be held. It is usually very difficult to predict how long the
synth note (as opposed to the natural guitar note) will be held, and the
dynamic level of the synth note is simply switched on or off at a fixed
level, depending on whether the natural guitar note level is above or
below a predefined threshold. The guitar synth to date does not offer
velocity or pressure parameters with which to make the control of the
synth more expressive. It is usually very difficult to predict the dynamic
performance of such a system.
For all of these reasons, the guitar synthesiser has never been really
successful.
Further examples of guitar synthesisers are described in various articles
in Sound International, in particular:
November 1980 (Electro-Harmonix, article by Robin Millar),
December 1978 (Roland G500, by Steve Hackett; ARP Avatar, by Paddy
Kingsland),
December 1979 (Fairlight CMI, by David Crombie),
May 1980 (general article "So you Want to Buy a Synth . . . ", by David
Crombie),
and also in The Guitar Book by Tom Wheeler, see the chapter on Guitar
Synthesisers at pages 289-292.
5. Other forms of Synthesiser Control
Some isolated attempts to operate a synthesiser from other input devices
have been made:
(a) The Lyricon--see Sound International May 1979, article by John Walters,
and also May 1978 page 23. The Lyricon looks like a wind instrument and
has a reed as well as keys which operate electric switches rather than
controlling the note produced by the reed. The dynamic performance
(attack, decay, sustain and release) is achieved by analysing the pressure
produced by blowing the mouthpiece, and deriving the appropriate control
voltages. Filter effects, and sliding effects (glissandi) can also be
derived from the mouthpiece transducer system.
(b) The Touch--manufactured by Oncor Sound Inc, 471 W. 5th South, Salt Lake
City, Utah 84101, United States of America, see also Sound International
September 1979 (News item), and UK Patent Application No. 2078427. This
instrument looks at first glance like a guitar, but has no strings over
the fingerboard section of the instrument. Instead the fingerboard has
embedded in it 96 touch-sensitive capacitative sensors corresponding to 16
finger positions for the 6 strings. The fingers of the left hand
(conventionally) thus select the note or chord to be sounded. The right
hand strikes an array of short strum bars which occupy the position
normally occupied by the lower section of a guitar. The strum bars are
used to trigger the notes selected by the left hand.
We have found that in actual fact this instrument proves to be difficult to
play, because the strings which normally guide the player to the correct
place on the fretboard are missing. Furthermore the number of notes which
can be played is limited by the area required for each capacitative
sensor.
The instrument is monophonic, and is relatively inflexible in that it can
not produce many of the effects to which a guitar player is accustomed.
(c) The Music Room--described in Guitar Player, October 1982, pages 58, 60
and 62. This instrument again has touch-sensitive panels on the fretboard,
though in this case there are 31 panels each extending across the full
width of the neck of the instrument. The positions of the touch-sensitive
panels on the neck no longer retain the precise distance relation required
in a normal guitar. Triggering of the notes is by means of further
touch-sensitive panels on the body of the instrument which correspond to
respective `strings` of the conventional guitar. Chord playing is not
analogous to a conventional guitar. Again, the instrument is monophonic
and relatively inflexible.
(d) The Kaleidophon--see Sound International September 1980, article by Sue
Steward. This has four strings each of tape about 1/8th inch (3 mm) wide,
laid over a long thin conductive surface mounted on the wooden neck. The
tape is pressed down onto the neck to play a note and the position at
which contact is made is detected by determining the resultant resistance.
This is inherently prone to inaccuracies. Note triggering is quite
different from a conventional guitar and the instrument is also incapable
of producing other effects familiar to the guitar player.
(e) U.S. Pat. No. 4,372,187 In this arrangement, the usual guitar strings
are split into two parts, with part of each string extending the length of
the neck and part being on the body of the instrument where it can be
plucked. The neck strings make electrical contact with conductive frets,
and the body strings initiate triggering of the notes determined by the
neck strings.
(f) U.S. Pat. No. 3,555,166 This patent describes an instrument which on
the neck has a first array of switches and on the body a second array of
switches. The second array contains six individual switches which trigger
the notes produced, and on the neck there are sufficient rows of six
smaller switches to cover the different notes to be played. However this
instrument is not attractive for the musician to play in view of the
number of switches on the neck which have an unusual feel.
SUMMARY OF THE INVENTION
The invention has various aspects which are defined in the appended claims,
to which reference should be made.
A preferred embodiment of the invention takes the form of a guitar-like
electronic musical instrument for use with a synthesiser having a body and
a neck. The neck carries six pitch strings, which the player depresses
onto conductive frets to determine the selected note. The body carries six
trigger strings which can be plucked or strummed to initiate or trigger
the desired notes. Alternatively they can be triggered by six keys. The
trigger strings and pitch strings are at an angle to each other. The three
lower strings and the three higher strings can be triggered together by
group trigger keys and all six strings triggered by a master trigger key.
If an appropriate switch is actuated, notes will be triggered
automatically as soon as the pitch string is depressed onto the fret.
Touching of the string is detected by an d.c. waveform superposed on a
d.c. potential. Hall effect devices are used to sense triggering by the
trigger strings or keys. Each fret has eleven conductive sections so that
sideways bending can be detected, and bend detection coils are embedded in
the fingerboard for the same purpose. A vibrato arm using a Hall effect
device can be used to introduce a vibrato effect. A console enables
resetting of the notes of each string, storing various set values for each
string, transposition of the instrument as a whole, and a `Capo` effect to
be obtained. A pedal unit allows some functions to be selectively operated
during playing, such as variation in the decay rate, or sustaining of
notes played while a hold pedal is depressed.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment will be described in more detail, by way of
example, with reference to the drawings, in which:
FIG. 1 is a representation of a trigger signal pulse;
FIG. 2 shows an idealized ADSR response;
FIG. 3 shows a practical digital ADSR response;
FIG. 4 illustrates the main components of a system embodying the invention;
FIG. 5 is a front view of a modification of the guitar-like instrument of
the system of FIG. 4;
FIG. 6 shows part of the neck;
FIG. 7 is a top view of the instrument;
FIG. 8 is a sectional view taken on the line X--X in FIG. 5;
FIG. 9 is a block circuit diagram of the string driver board circuitry;
FIG. 10 is a plan view of part of a fingerboard embodying the invention;
FIG. 11 is an elevational view of one of the contact pins;
FIG. 12 is a plan view of the head of the pin;
FIG. 13 illustrates the electrical connection of the pins;
FIG. 14 diagrammatically illustrates a string pressed against the
fingerbroad at one point;
FIG. 15 diagrammatically illustrates a string pressed against the
fingerboard at two points;
FIG. 16 is a schematic plan view of part of a second fingerboard embodying
the invention showing one fret position;
FIG. 17 is a detail sectional view across the neck of the instrument;
FIG. 18 is a plan view of one of the intermediate fret pins of FIG. 16 on a
larger scale;
FIG. 19 is a front elevantional view of the pin;
FIG. 20 is a side elevational view of the pin;
FIG. 21 is a partial elevational view taken on the arrow A in FIG. 6;
FIG. 22 is a plan view of one of the two external fret pins of FIG. 16;
FIG. 23 is a front elevational view of the pin of FIG. 22;
FIG. 24 is a block diagram showing the main components of the electronic
system;
FIG. 25 is a circuit diagram of one possible form for the touch sensor
circuit;
FIG. | | |
