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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electrical string-instrument.
2. Description of the Prior Art
In recent years, the so-called electrical guitar has widely been used as an
electrical string-instrument. The electrical guitar has six strings and a
support member having a major surface which includes a string receiving
surface and on which the strings are stretched in substantially the same
plane in parallel relation to one another and in opposing relation to the
string receiving surface. On the string receiving surface of the support
member, a plurality of frets which extend substantially at right angles to
the strings, are sequentially provided in the direction of extension of
the strings. Further, in the area other than the string receiving surface
in the area opposite to the strings, there are provided electromechanical
transducer means for converting mechanical vibrations of the strings into
corresponding electrical signals.
When playing the guitar, the player touches a desired one or more of the
strings while pressing or not pressing them against the string receiving
surface with his fingers. A sound signal which is obtained from the
electromechanical transducer means when picking the guitar without
pressing the string against the string receiving surface, is called an
open-string sound signal. In the case of pressing the string against the
string receiving surface with the finger, the sound signal derived from
the electromechanical transducer means has a higher frequency than the
abovesaid open-string sound signal. The reason is that the string is urged
against the fret nearest the pressed position on the side of the
electromechanical transducer means with respect to the position where the
string is pressed. In the case of picking an ordinary electrical guitar,
the string picked by the finger performs a damped oscillation.
Accordingly, the amplitude of the sound signal derived from the
electromechanical transducer means is attenuated with the lapse of time.
Therefore, it is impossible with the ordinary electrical guitar to obtain
a sound signal having a sustain effect.
Heretofore, attempts have been made to obtain the sound signal having the
sustain effect with the electrical guitar. However, no satisfactory
electrical guitar has been obtained for the reasons that the electrical
guitar becomes bulky, and that the sound signal obtained from the
electromechanical transducer means is unstable.
SUMMARY OF THE INVENTION
Accordingly, a primary object of this invention is to provide a novel
electrical string-instrument which is simple in construction but capable
of stably producing an electrical sound signal having the sustain effect.
Another object of this invention is to provide a novel electrical guitar
which is simple in construction but capable of stably producing an
electrical sound signal having the sustain effect.
Other objects, features and advantages of this invention will become more
fully apparent from the following description taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view schematically illustrating an embodiment of this
invention as being applied to an electrical guitar;
FIG. 2 is a cross-sectional view schematically showing an example of an
electromechanical transducer for use in the electrical guitar depicted in
FIG. 1;
FIG. 3 is a cross-sectional view schematically showing an example of
magnetic field generating means for use in the electrical guitar shown in
FIG. 1;
FIG. 4 is a schematic diagram illustrating an example of the electrical
construction of the electrical guitar shown in FIG. 1;
FIG. 5 is a schematic front view showing another example of the electrical
guitar of this invention;
FIG. 6 is a schematic cross-sectional view illustrating an example of a
common electromechanical transducer for use in the electrical guitar
depicted in FIG. 5; and
FIG. 7 is a schematic diagram showing an example of the electrical
construction of the electrical guitar depicted in FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, reference numeral 1 indicates generally an example of an
electrical guitar of this invention, which has six conductive and magnetic
strings A.sub.1, A.sub.2, . . . A.sub.6 and a nonconductive support member
4 which has a major surface 3 including a string receiving surface 2 and
on which the strings A.sub.1 to A.sub.6 are stretched in substantially the
same plane in parallel relation to one another and in opposing relation to
the string receiving surface 2.
On the string receiving surface 2 of the support member 4, a plurality of
conductive frets B.sub.1, B.sub.2, . . . , which extend substantially at
right angles to the direction of extension of the strings A.sub.1 to
A.sub.6, are sequentially disposed in the direction of extension of the
strings A.sub.1 to A.sub.6. That part of the support member 4 which has
the string receiving surface 2 is referred to as a neck portion 5. The
part which includes an area 6 of the major surface 3 of the support member
4 except the string receiving surface 2 in the area opposite to the
strings A.sub.1 to A.sub.6, is called a body 7. The neck portion 5 extends
upwardly from the body 7. At the lower side of the area 6 of the body 7,
there are disposed fixing means 8, to which the strings A.sub.1 to A.sub.6
are fixed at one end. The other ends of the strings A.sub.1 to A.sub.6 are
respectively retained at individual fixing means F.sub.1, F.sub.2, . . .
F.sub.6 which are provided on the upper end portion of the neck portion 6
and each have a screw 9 for adjusting the tension of the string. A little
above the fixing means 8 on the area 6 of the body 7, a fret 11 is
provided for bridging the strings A.sub.1 to A.sub.6. Disposed slightly
below the fixing means F.sub.1 to F.sub.6 on the neck portion 5 is a fret
10 for similarly bridging the strings A.sub.1 to A.sub.6. The strings
A.sub.1 to A.sub.6 are held by the frets 11 and 10, by which they are
stretched to extend on the support member 4 in substantially the same
plane in parallel relation to each other and in opposing relation to the
string receiving surface 2.
At lower positions in the area 6 of the body 7, electromechanical
transducer means C.sub.1, C.sub.2, . . . C.sub.6 for converting mechanical
vibrations of the strings A.sub.1, A.sub.2, . . . A.sub.6 into
corresponding electrical signals E.sub.1, E.sub.2, . . . E.sub.6 are
sequentially disposed in the direction of array of the strings A.sub.1 to
A.sub.6 in opposing relation thereto. An example of each of the
electromechanical transducer means C.sub.1 to C.sub.6 is such a magnetic
head type one as shown in FIG. 2 which comprises a bar or plate-like
magnet 21, a magnetic core 22 coupled at one end with one end of the
magnet 21, another magnetic core 23 coupled at one end with the other end
of the magnet 21 and having the other end disposed opposite to the other
end of the magnetic core 22 to form an air gap g, and a coil 24 composed
of two parts respectively wound on the cores 22 and 23. The
electromechanical transducer means Ci (i=1, 2, . . . 6) is disposed
opposite to the string Ai so that the widthwise direction of the air gap g
may be substantially perpendicular to the direction of extension of the
string Ai. Accordingly, when the string Ai is vibrated by being touched at
the portion opposing the surface of the area 6, a vibration voltage, which
corresponds to the components of vibration in the direction perpendicular
to the surface of the area 6, is obtained as an electrical sound signal Ei
across the coil 24 of the magnetic head type means Ci.
At the upper position in the area 6 of the body 7, there is disposed
magnetic field generating means 31 which sets up a constant magnetic field
to cover the strings A.sub.1 to A.sub.6. An example of the magnetic field
generating means 31 is such, for example, as depicted in FIG. 3, which
comprises two bar or plate-shaped magnets 32 and 33 disposed on both sides
of an area corresponding to the area of array of the strings A.sub.1 to
A.sub.6 in their widthwise direction, and a magnetic core 34 extending
between one end of the magnet 32 and one end of the magnet 33. In this
case, the one end of the magnet 32 coupled with the core 34 forms the
magnetic north pole and the other end the magnetic south pole. Further,
the one end of the magnet 33 coupled with the core 34 forms the magnetic
south pole and the other end the magnetic north pole. Accordingly, at the
upper position in the area 6 of the body 7, there is generated a magnetic
field 35 emanating from the magnetic north pole of the magnet 33 to the
magnetic south pole of the magnet 32 in a direction perpendicular to the
direction of extension of the strings A.sub.1 to A.sub.6 to cross them.
Therefore, if a current flows in the string Ai, the string Ai is moved by
the Fleming's law in the direction perpendicular to the area 6 in
accordance with the direction of the current flowing in the string Ai, as
indicated by the arrows 36 and 37.
The body 7 has disposed therein an electrical circuit 41 indicated by the
broken-line block in FIG. 1. In the electrical circuit 41, as shown in
FIG. 4, the electrical sound signals E.sub.1, E.sub.2, . . . E.sub.6
respectively derived from the coils 24 of the electromechanical transducer
means C.sub.1, C.sub.2, . . . C.sub.6 are amplified by preamplifiers
G.sub.1, G.sub.2, . . . G.sub.6, and then supplied to threshold circuits
J.sub.1, J.sub.2, . . . J.sub.6 through ganged switches H.sub.1, H.sub.2,
. . . H.sub.6, respectively, by which signals, shaped into rectangular
waveforms which are "1" or "0" in the binary representation depending upon
whether the electrical sound signals E.sub.1, E.sub.2, . . . E.sub.6 are
above or below predetermined levels, respectively, are obtained as
feedback signals M.sub.1, M.sub.2, . . . M.sub.6. Then, the signals
M.sub.1, M.sub.2, . . . M.sub.6 thus obtained are amplified by driving
amplifiers K.sub.1, K.sub.2, . . . K.sub.6, respectively. An actuator 38
for the ganged switches H.sub.1 to H.sub.6 is provided on the major
surface 3 in the area on the body 7.
The outputs of the driving amplifiers K.sub.1, K.sub.2, . . . K.sub.6 of
the electrical circuit 41 are respectively connected at one end to the
ends of the strings A.sub.1, A.sub.2, . . . A.sub.6 on the side of the
fixing means 8, and grounded at the other end. Also, the abovesaid
conductive frets B.sub.1, B.sub.2, . . . are grounded. Accordingly, when
the string Ai is picked by one finger at the position opposite to the area
6 while being urged by another finger against the string receiving surface
2 and engaged with the fret Bj (j=1, 2, . . . ), the feedback current Ii
based on an amplified feedback signal Mi derived from the driving
amplifier Ki flows in the string Ai as long as the string Ai is pressed
against the string receiving surface 2 and engaged with the fret Bj.
Consequently, if the polarity of the feedback signal Mi is selected such
that the string Ai may be moved by the Fleming's law in the same direction
as the direction of vibration of the string Ai when touched, when the
string Ai has once been touched by finger while being urged against the
string receiving surface 2 and engaged with the fret Bj, the string Ai
continues to vibrate as long as it is pressed against the string receiving
surface 2 and engaged with the fret Bj. Accordingly, the sound signal Ei
from the electromechanical transducer Ci or preamplifier Gi is obtained as
a sound signal corresponding to the continuous vibration of the string Ai.
Such a signal is called a sound signal having the sustain effect. Further,
when released from the abovesaid pressed state, the string Ai immediately
starts to perform damped vibration. As a result of this, the sound signal
Ei from the electromechanical transducer Ci or preamplifier Gi is obtained
as a damped sound signal. The sound signals E.sub.1 to E.sub.6 derived
from the preamplifiers G.sub.1 to G.sub.6 are led out as one kind of
output from the electrical circuit 41 to the outside through a multi-jack
43 disposed on the side 42 of the body 7. Further, the sound signals
M.sub.1 to M.sub.6 having rectangular waveforms, derived from the
threshold circuits J.sub.1 to J.sub.6, are similarly led out as the other
kind of output from the electrical circuit 41 to the outside through a
multi-jack 44 disposed on the side 42 of the body 7.
Further, the electrical circuit 41 is designed so that the amplified
electrical sound signals E.sub.1 to E.sub.6 from the preamplifiers G.sub.1
to G.sub.6 are mixed by the mixing circuit 45 to derive therefrom a signal
EO into which the electrical signals E.sub.1 to E.sub.6 are combined. The
electrical signal EO thus obtained from the mixing circuit 45 is led out
as another kind of output from the electrical circuit 41 to the outside
through a jack 46 provided on the side 42 of the body 7. Accordingly, if
the electrical guitar of this invention is picked in the state in which
the abovesaid switches H.sub.1 to H.sub.6 are held in the off state by the
aforementioned actuator 38, the feedback signal M.sub.1 to M.sub.6 are not
derived from the threshold circuits J.sub.1 to J.sub.6, so that the
currents I.sub.1 to I.sub.6 do not flow in the strings A.sub.1 to A.sub.6.
As a result of this, the electrical sound signals E.sub.1 to E.sub.6 from
the electromechanical transducer means C.sub.1 to C.sub.6 are not the
sound signals corresponding to the abovesaid continuous vibration of the
string, so that the signal EO led to the outside through the jack 46 is
obtained as a sound signal of the same mode as a sound signal obtained
with an ordinary electrical guitar. However, when the electrical guitar of
this invention is picked with all or some of the strings A.sub.1 to
A.sub.6 urged by fingers against the string receiving surface 2 in the
state in which the switches H.sub.1 to H.sub.6 are held in the on state by
the actuator 38, electrical sound signals derived from all or some of the
electromechanical transducer means C.sub.1 to C.sub.6 corresponding to the
strings pressed against the string receiving surface 2 in this case are
obtained as sound signals corresponding to the aforesaid continuous
vibration, so that the signal EO led out to the outside through the jack
46 is a sound signal having the sustain effect. Further, the electrical
circuit 41 has a mixer 47 which is adapted such that the feedback signals
M.sub.1 to M.sub.6 of the rectangular waveform, derived from the threshold
circuits J.sub.1 to J.sub.6 are mixed together to provide a composite
signal MO. The signal MO thus obtained from the mixer 47 is led out as
another kind of output from the electrical circuit 41 to the outside
through a jack 48. Accordingly, when the guitar is played in the state
that the switches H.sub.1 to H.sub.6 are closed by the operation of the
actuator 38, the sound signal MO of rectangular waveform having the
sustain effect is led out to the outside.
FIGS. 5, 6 and 7 illustrate other embodiments of the electrical guitar of
this invention. In FIGS. 5, 6 and 7, the parts corresponding to those in
FIGS. 1 to 4 are identified by the same reference numerals and no detailed
description will be repeated.
At the center of the area 6 of the body 7, there is disposed opposite to
the strings A.sub.1 to A.sub.6 electromechanical transducer means C' which
converts mechanical vibrations of the strings A.sub.1 to A.sub.6 into a
composite signal E' of electrical signals corresponding to the vibrations
and which is common to the strings A.sub.1 to A.sub.6. The
electromechanical transducer means C' is, for instance, such a multigap
magnetic head type one as shown in FIG. 6, which is composed of a bar or
plate-like magnet 51, a magnetic core 52 coupled at one end with the
magnet 51, another magnetic core 53 coupled at one end with the other end
of the magnet 51 and having the other end disposed opposite to the
magnetic core 52, magnetic core elements p.sub.1, p.sub.2, . . . p.sub.5
disposed between the other ends of the magnetic cores 52 and 53 to form
airgaps g.sub.1, g.sub.2, . . . g.sub.6, and a coil 54 composed of two
parts respectively wound on the magnetic cores 52 and 53. The
electromechanical transducer C' is disposed opposite to the strings
A.sub.1, A.sub.2, . . . A.sub.6 so that the widthwise directions of the
gaps g.sub.1, g.sub.2, . . . g.sub.6 may be substantially perpendicular to
the direction of extension of the strings A.sub.1, A.sub.2, . . . A.sub.6.
Accordingly, when the string Ai is vibrated by touching, a vibration
voltage which corresponds to the components of vibration in the direction
perpendicular to the surface of the area 6 is obtained as the electrical
sound signal E' across the coil 54 of the magnetic head type means C'.
Further, when some or all of the strings A.sub.1 to A.sub.6 are
simultaneously vibrated by touching, a voltage that vibration voltages
corresponding to the components of the vibrations in the direction
perpendicular to the major surface 3 is obtained as the electrical sound
signal E'.
The other electrical circuit 61 is disposed in the body 7 and adapted so
that the electrical sound signal E' derived from the coil 54 of the
electromechanical transducer means C' is supplied to an amplifier 62
through a volume 63, and then amplified by the amplifier 62, as shown in
FIG. 7. An actuator 64 for the volume 63 is disposed on the surface of the
body 7, as illustrated in FIG. 5.
Further, the body 7 has incorporated therein a circuit 65 for combining the
electrical sound signal MO from the mixer 47 of the electrical circuit 41
with the amplified electrical sound signal E' from the amplifier 62 of the
electrical circuit 61 to provide a composite signal EM. The composite
signal EM is led out to the outside through a jack 66 provided on the side
42 of the body 7. In this case, however, volumes Q.sub.1 to Q.sub.6 are
provided on the input side of the mixer 47 in the electrical circuit 41.
Actuators U.sub.1 to U.sub.6 for the volumes Q.sub.1 to Q.sub.6 are
disposed on the surface of the body 7, as shown in FIG. 5. Accordingly,
where the switches H.sub.1 to H.sub.6 of the electrical circuit 41 are
closed by their actuator 38, the signal EM is obtained as a composite
sound signal that the rectangular sound signals M.sub.1 to M.sub.6 having
the sustain effect and adjusted in amplitude, which are led out to the
outside through the jack 66, and the sound signal E' having the sustain
effect are combined with each other. However, in the case where the
switches H.sub.1 to H.sub.6 are not closed, the signal EM led out to the
outside through the jack 66 is obtained as a signal similar to that
obtainable with an ordinary electrical guitar.
The foregoing illustrates only a very few embodiments of this invention.
For example, in the embodiment of the electrical guitar of this invention
described previously with regard to FIGS. 1 to 4, desired one, two or
three of the pair of the mixer 45 and the jack 46, the jack 43, the pair
of the mixer 47 and the jack 48 and the jack 44 may be omitted. Further,
it is possible to provide the mixers 45 and 47 in an electrical sound
signal processing circuit separately of the electrical guitar 1 instead of
providing them in the body 7. Also, in the embodiment of the electrical
guitar of this invention shown in FIGS. 5 to 7, the mixer 65 may be
provided in an electrical sound signal processing circuit provided
separately of the guitar 1. In the foregoing, magnetic head type
transducers are used as the electromechanical transducers, but may also be
of the electrostatic head type. In such a case, the strings need not be
magnetic. Moreover, the foregoing has described the embodiments of the
present invention as applied to the electrical guitar but it should be
understood that the invention is also applicable electrical
string-instruments similar to the electrical guitar.
It will be apparent that many modifications and variations may be effected
without departing from the scope of novel concepts of this invention.
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