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Патент USA US3084593

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April 9, 1963
M. E. ANDERSON
‘
3,084,583
TONE GENERATION SYSTEM
Filed Oct. 20, 1958
2 Sheets-Sheet 1
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Mart/Ln E Anderson
April 9, 1963
M. E- ANDERSON
3,084,583
TONE GENERATION SYSTEM
Filed Oct . 20, 1958 ‘
2 Sheets-Sheet 2
he afar
Marvin 5. Anderson
United States Patent 0
3,084,583
Patented Apr. 9, 1963
1
2
3,084,583
FIGURE 10 illustrates a third way of connecting the
TONE GENERATION SYSTEM
Marvin E. Anderson, Chicago, Ill, assignor, by mesne
assignments, to Everett Piano Company, South Haven,
Mich, a corporation of Delaware
Filed Oct. 20, 1958, Ser. No. 768,131
3 Claims. (Cl. Slim-1.16)
strings in series;
FIGURE 11 is an enlarged perspective view of a clip
used in FIGURE 10;
FIGURE 12 illustrates a fourth method of connect
ing the strings in series;
FIGURE 13 is an enlarged perspective view of a
This invention relates generally to an improved elec
tronic piano, and more speci?cally to an improved sim
clip used in FIGURE 12; and
pli?ed tone generation system incorporated therein.
the strings in series.
Although the principles of the present invention may
be included in various musical instruments, a particularly
useful application is made in an electronic piano of the
lightweight type which can be sold at a somewhat lower
price .than conventional pianos.v
FIGURE 14 illustrates a ?fth means for connecting
As shown on the drawings:
The principles of the present invention are particularly
useful when embodied in an electrical musical instru
ment or piano such as illustrated in FIGURE 1, gener
15 ally indicated by the numeral 10.
The piano 10 in
cludes a cabinet 11 supporting a string frame assembly
12 and an action assembly diagrammatically illustrated
in the art. These pianos have had various faults or dif
by the hammer 13 for exciting a string 14 of the string
?culties, one of which is an excessive degree of com
frame assembly 12. An electrical ?eld producing mem
plexity, particularly in the electrical details employed
20 ber 15, described in greater detail later herein, is also
in the generation of the musical tones.
included in the string frame assembly 12, and commu
Accordingly, it is a principal object of the instant
‘Broadly speaking, electronic pianos are old and known
invention to provide a simpli?ed tone generation system
for an electronic piano.
It is the further object of the present invention to
nicates electromechanically with .the strings for convert
ing the vibrations thereof into electrical signals. The
strings 14 communicate electrically with an electronic
provide a simpli?ed tone generation system incorporat 25 ampli?er 16 which drives a speaker 17, both supported
ing novel simpli?ed means for providing a magnetic ?eld
adjacent to portions of the various strings of the piano.
by the case 11. Conventional structure may be utilized
for each of the components not described in detail in
the instant speci?cation, such as the ampli?er 16, the
A still further object of the present invention is to
speaker 17, the cabinet 11 and the hammer 13.
provide a tone generation system of the type wherein
Referring now to the circuit diagram of FIGURE 2,
the strings are electrically connected together, and where 30
the instant tone generation system includes a plurality
in novel means are provided for effecting such connec
tion together of the tuned strings.
Many other advantages, features and additional objects
of the present invention will become manifest to those
of the strings 14 which are each secured at one end
to a hitch pin or string-supporting pin 20 and at the
other end to a tuning pin or string-supporting pins 21
versed in the art upon making reference to the detailed 35 as shown in FIGURE 1.
description and the accompanying sheets of drawings in
which preferred structural embodiments incorporating the
principles of the present invention are shown by way of
illustrative example.
On the drawings:
FIGURE 1 is an elevational view of a piano equipped
The frame 12 has a hear
ing edge or bridge 22 adjacent to the tuning pins 21,
and has a second bearing edge or bridge 23 adjacent to
the hitch pins 20. The bridges 22 and 23 are spaced
apart so as to jointly de?ne the speaking portion or vibrat
40 ing portion of each of the strings 14.
The number of strings 14 corresponds exactly to the
number of notes in the series which the instrument 10
provides. Thus, one feature of the instant invention is
with the principles of the present invention, portions of
that only one string is provided per musical note.
the illustrated embodiment of the invention being broken
4:5
The circuit illustrated in FIGURE 2 has 88 strings
away and other structural portions of a known environ
with a tone generation system provided in accordance
mental nature being shown largely diagrammatically to
simplify the illustration;
FIGURE 2 is a diagrammatic view of the electrical
representing the quantity required for a full scale piano
having a standard keyboard. Each of the tuning pins
21 is so adjusted that the strings ‘14 are tuned to pro
vide an equal tempered chromatic scale, such as one
circuit employed in .the tone generation assembly shown
50 with a standard pitch for each string. Thus there is a
in FIGURE 1;
series of hitch pins 20 which are spaced from each other
FIGURE 3 is an enlarged plan view, fragmentary in
and which are supported by the string frame of the
nature, of a ?eld producing portion of FIGURE 2, taken
string frame assembly 12. In this embodiment, each of
near the right end thereof;
FIGURE 4 is a perspective fragmentary view of a 55 the hitch pins 20 is electrically isolated from each other,
insofar as its support is concerned.
different ?eld~producing portion of FIGURE 2, taken
near the left end thereof;
FIGURE 5 is a front elevational view substantially
Thus also there is provided a series of the tuning pins
21 each of which is supported by the frame of the frame
assembly 12 in spaced relation to each other, and each of
which is also electrically insulated from the other pins,
of the fragmentary portion of the structure shown in
FIGURE 4;
60 insofar as the support is concerned. Since the string
FIGURE 6 is a slightly modi?ed form of ?eld produc
frame of the string frame assembly 12 is substantially
ing means, generally similar to the embodiment shown
?at, the various vibratory strings ‘14 are each supported
in FIGURES 3 and 4;
and tensioned between a hitch pin 20 and a tuning pin
FIGURE 7 is a fragmentary view of a string frame
21, and disposed by them substantially in a plane.
65
assembly showing one means for connecting the strings
While the means 15 has been broadly termed a ?eld
in series;
.
producing member, it is more accurately a series of
FIGURE 8 is generally similar to FIGURE 7, but
means for providing magnetic ?elds about a portion of
illustrates a second means for connecting the strings in
each of the strings 14. As shown in FIGURE 2, the ?eld
producing member 15 may be subdivided into several
series;
FIGURE 9 is an enlarged perspective view of a clip 70 components and may be provided in various angles and
lengths.
used in FIGURE 8;
3,084,583
3
4
connected to the ampli?er 16 which strengthens the sig»
Referring now to FIGURES 3-5, the magnetic ?eld
means in this embodiment is shown to include an elon
nal so that they can be converted to sound by the speak
gated non-rnagnetic base 3d, which in this embodiment
er 17.
comprises wood. As best seen in FIGURE 1, the base
3t) is supported in ?xed relation to the string (frame as
‘It will be noted that the means for producing the mag-1
netic ?eld can be manufactured employing only cut-off
equipment, since cement may be employed to secure the
sembly '12 by the string frame itself, and in a position
adjacent to a group of the strings 14, in parallel relation
elements 31 to the base 30.
to the plane in which the strings 14 lie. To the one sur
Referring now to FIGURE 6, there is shown another
face of the base 30 which is adjacent to the strings 14,
embodiment of the means for producing a series of mag
10 netic ?elds about a series of the strings. This means also
there is attached a series or group of ?at wafer-like mag
netic elements 31, 32, which comprise permanent magnets.
The magnetic elements 31, 32 are ?xedly secured in ?at
wise relation against the base 30 and are disposed in
spaced relation to each other.
it will thus be seen that
includes an elongated non-magnetic base 40‘ to which is
attached a'group of ?at wafer-like magnetic elements 41,
each of which is ?xedly secured as by cementing in ?at
wise relation against the base 40‘ in spaced relation to
edges of adjacent elements which confront each other 15 each other. vA pair of magnetic support members 42, 42
jointly de?ne a gap within which a string 14 is disposed
as seen in FIGURES 3 and 5. The magnetic elements
is secured to the ends of the non-magnetic base 44}. Each
of the members '42 communicates magnetically with one
of the magnetic elements 41 and is adapted to be sup‘
ported by the string frame of the string frame assembly
It will be noted that along one polar edge,‘ there is but 20 12 in ?xed relation adjacent to a group of the strings 14;,
parallel to the plane in which the strings are disposed,
one polarity so that each of a pair of adjacent spaced
There is also provided a single permanent magnet 43
edges has continual but mutually opposite magnetic
which is longitudinally magnetized so that its poles com“
polarities, whereby a single polarity is provided at each
municate magnetically with each of the magnetic mem*
side of the gap without there being a null point along
31, 32 have such magnetic polarity that the confronting
edges which de?ne the gap also have the magnetic poles.
25 bers 42 remotely from the magnetic elements 411. In
the length of the gap.
this embodiment, the screws 44 serve not only to hold
Where the magnetic elements 31, 32 are made up from
the members 42 to the base 40, but also to serve to clamp
premagnetized strips of a permanent magnet, such strips
the permanent magnet 43 therebetween. Of course, the
being transversely magnetized, they may be cut to dif
magnetic force of the permanent magnet 43 also serves to
ferent lengths, as illustrated by the diiference in lengths
between the elements 31 and 32., so as to thereby se
lec'tably determine the amount of ?ux which is present
around a particular string. Therefore, it is apparent that
the magnetic ?ux will be somewhat greater between the
elements 31 and 32 than it will be between a pair of the
30 assist in holding the magnet 43 in place.
The magnetic path from the magnet 43 extends through
the members 42 and thence to the magnetic elements 41;
Each of the air gaps between the magnetic elements 41
is a magnetic gap in the circuit which individually re
This difference is utilized to obtain a 35 ceives one of the strings 14, and which collectively have
substantially the same effect as a single gap in the circuit
uniform well~balanced ensemble of strings.
having a width equal to the sum of the separate gaps. I
If desired, the base 30 may be undercut as at 30a, the
have found that this form of construct-ion is advantageous
undercut 30a serving as an extension of the gap between
in that a single strong magnet is employed in an extremely
two of the magnetic elements. The undercut serves two
functions. First it acts as a gage for the alignment of 40 simple structure to provide a whole series of magnetic
gaps. Each of the magnetic elements thus has an edge
individual elements 31, 32, and secondly, it provides
which ‘de?nes a side Oif a gap, and which edge has a mag
clearance for string vibration.
netic polarity that is continuous along the length of the
It is to be understood however, that the slots 30a
gap without there being a null point in the gap. Thus a
may be omitted as shown in FIGURE 5, and that the
elements 31 may be of the same length as shown in 4.5 given pair of spaced polar edges have continual but op»
posite magnetic polarities respectively. Once this em
FIGURE 3.
bodiment of means for producing a magnetic ?eld is in
As shown in FIGURE 2, there is a series of means
elements 31, 31.
stalled in the string frame assembly 12, its operation is
provided at each of the ends of the strings 14 whereby
identical to that already described above.
all of the strings are connected together in a single series
Referring again to FIGURE 2, it can be seen that an
circuit. This is illustrated in FIGURE 2 by the wires 33 50
88-note tone generation system of this type requires 176
and the wires 34. Further, means is provided for cou
connections of the type made by the wires 33—36 to
pling the ends of the circuit to the audio ampli?er 16,
place them electrically in series. Apart from the labor
which in this embodiment includes a wire 35, a wire 36,
factor, there are ‘other considerations which must be
and a coupling transformer 37. When one of the
polyphonically tuned strings 14 is excited into vibration 55 given due regard in effecting the connection between the
strings. Among these are electrical characteristics, econ
by being struck by the hammer 13, that portion of the
omy, corrosion eifects, serviceability, and appearance.
string 14 which is disposed within the magnetic ?eld be
However, perhaps the most important is that the connec
tween the permanently magnetic elements 31, cuts across
tions between the piano wires must be secure so that vi
the magnetic lines of force in the gap to induce a current
in the wire. I have found that where a single wire is 60 bration will not loosen or cause intermittent or elec
trically noisy contact. Since the resistance of all of the
used per note, and particularly when miniaturized or
strings in series and the voltage produced by them are
relatively short low tensioned strings are employed in the
both low, any further resistance added in series with the
electronic piano, all of the strings may be connected in a
strings by poor or resistive connections reduce sensitivity
single series. The total electrical resistance of all the
strings, even though made of piano wire, does not ad 65 and also reduces the signal-to-noise ratio when a coupling
transformer is employed. Obviously, if the transformer
versely affect the operation of the piano. I have also
were omitted, resistive connections would not be critical
found that when the strings are connected as shown, the
to the performance of the system, the series of connected
various electrical signals which may exist simultaneously
in the circuit when the piano is played do not interfere 70 strings then being in communication directly with an am- '
.pli?er grid.
constructively or destructively with each other, other than
One of the disadvantage of wires soldered to the strings
to the extent which simultaneously existing sounds com
as jumpers, is that a considerable amount of labor is
bine. Thus the composite of all of these signals gener
needed and some skill is required. Moreover, if cold
ated by and within the strings is conducted by the wires 35
and 36 to the step-up coupling transformer 37 which is 75 soldered joints result from inadequate heat or the like,
3,084,583
6
arcuate ‘end portions are relatively sharp, and since they
are disposed to engage the pin 21, they tend to bite in and
sensitivity of the system is reduced due to the added re
sistance of the series connection.
to hold or wedge in a positive manner.
Accordingly, there is also presented here the teaching
of several methods of producing e?ective connections.
It is thus apparent that the instant tone generation sys~
tem is extremely simple and foolproof. The position of
Referring ?rst to FIGURE 7, it can be seen that each
of the series of means connecting all of the strings to
the string laterally within the magnetic gap is not critical
assuming of course that the string does not touch the
magnetic elements during vibration. The transverse po
sition of the string in the magnetic gap is not critical pro
jointly de?ne the speaking length thereof. The elements
vided
that the string is wholly within the gap. Adjust
45 comprise conductive inserts which are supported by 10 ment for sensitivity of pickup of individual strings or
the bridges 22, 23, the bridges 22, 23 being insulative
groups may be made by disposing the string partly out of
material. Thus the bridge elements 45 are supported by
the
gap.
the string frame in positive electrical engagement with
Although various minor modi?cations might be sug
each of a pair of adjacent strings 14.
gested by those versed in the art, it should 'be understood
Referring now to FIGURES -8, l0, l2, and 14, the 15 that I wish to embody within the scope of the patent
string frame assembly 12 may also employ a bridge 22
warranted hereon all such embodiments as reasonably
which is provided with a common insulative bridge ele
and properly come within the scope of my contribution
ment 46 such as of hard plastic.
to
the art.
The form shown in FIGURE 14 further includes a
I claim as my invention:
series of electrical terminals 47 insulatedly carried by the 20
1. In a tone generation system for an electronic piano
frame 12 and disposed adjacent to each of the tuning pins
having a string frame, a series of spaced hitch pins and
21 and hitch pins 20. The strings 14 in this embodi
a series of spaced tuning pins, each pin being supported
ment are provided with free ends 14a which extend from
by
the frame in electrical isolation from each other, a
each of the tuning pins 21 and which are mechanically
series of polyphonically tuned vibratory strings corre
and electrically secured to the terminal 47. Thus this 25 sponding in number to the number of notes in the piano
embodiment also provides means for connecting the
and each tensionably supported between one of the hitch
gether in a single circuit can comprise a series of bridge
elements 45 disposed at opposite ends of the strings to
strings together which means is supported by the string
pins and one of the tuning pins in a plane, means connect
frame in positive electrical engagement with each of a
pair of adjacent strings. This ‘form is also disadvan
tageous as compared to other forms in that a consider
able amount of labor is needed in the installation.
Referring now to ‘FIGURES 10 and 11, there is shown
ing said strings together in a conducting circuit, and means
30 for coupling the ends of the circuit to an ampli?er, the
improvement in combination therewith comprising: an
elongated non-magnetic base supported by the string frame
adjacent to a group of the strings and disposed parallel
to said plane; and a group of ?at wafer-like permanent
ous pairs of strings so as to effect a suitable circuit. In
35 magnets ?xedly secured in flatwise relation against said
FIGURE 11, there is shown an electrically conductive
non-magnetic base and lying in the plane of the strings
clip 48 which has abroad lower resistance central region
in spaced relation to each other, and polar edges of adja
and which is provided with a pair of arcuately formed
cent magnets facing directly toward each other and joint
end portions 49, 49, the end portions 49 each having an
ly de?ning an air gap therebetween, the poles of said mag
a preferred form for making the connection between vari
outwardly or concavely directed surface.
As best seen
in FIGURE 10, the end portions 49 are received by the
string frame 12 in the holes provided therein for the tun
ing or hitch pins. Thus the clips engage and electrically
connect adjacent pairs of hitch and tuning pins, and thus
nets being so arranged that each magnet has only one
are supported by the string frame in positive electrical
engagement with each of a pair of adjacent strings. The
clips 48 are inserted in the string frame before the hitch
the frame in electrical isolation from each other, a series
pins are inserted, and then the pins are driven in in a con
magnetic polarity at said gap.
2. In a tone generation system for an electronic piano
having a string frame, a series of spaced hitch pins and a
series of spaced tuning pins, each pin being supported by
of polyphonically tuned vibratory strings corresponding in
number to the number of notes in the piano and each ten
sionably supported between one of the hitch pins and one
ventional way, thereby assuring an extremely tight and
of the tuning pins in a plane, means connecting said strings
close ?t.
50 together in a conducting circuit, and means for coupling
Referring now to FIGURES 8 and 9, there is shown
a slightly different form of electrically conductive clip
50, which likewise has arcuately formed end portions 51
adapted to engage and electrically connect adjacent pairs
the ends of the circuit to an ampli?er, the improvement
in combination therewith comprising: an elongated non
magnetic base supported in ?xed relation to the string
frame and adjacent to a group of the strings in parallel
of hitch and tuning pins as shown in FIGURE 8. The 55 relation to said plane; a group of flat wafer-like elements
material from which the clip 50‘ is made is an electrically
?xedly secured in ?atwise relation directly against said
conductive spring material. The end portions 51 are
integral with the clip 50' and comprise resilient semi
non-magnetic base in spaced relation to each other, the
confronting edges of a pair of adjacent elements respec
cylindrically formed end portions, which concentrically
tively having continual opposite magnetic polarities and
receive a pair of pins 20, 20 or 21, 21, and electrically 60 de?ning an air gap for a string therebetween wherein
connect the same together. This form of clip is par
there is a single magnetic polarity at each side of said gap.
ticularly advantageous for field service since it can be
3. In a tone generation system for an electronic instru
readily attached to or removed from an assembled piano.
ment‘having a series of polyphonically tuned vibratory
It is further advantageous in that it provides a relatively
strings disposed in a plane and connected electrically to
large area of contact surface between the clip 50 and the 65 gether in a circuit, the improvement comprising: an elon
gated non-magnetic base disposed adjacent to a group
respective pins 20, 21.
Referring now to FIGURES l2 and 13, there is shown
of the strings in parallel relation to said plane; a group
a still ‘further form of electrically conductive clip 52.
of more than two ?at wafer-like magnetic elements ?xed
ly secured in ?atwise relation directly against said non
The clip 52 is provided with a pair of integral longitu
dinally extending resilient ?ngers 53, 53, each of which 70 magnetic base in spaced relation to each other, and pairs
is provided with a concavely formed end portion 530.
As best seen in ‘FIGURE 12, the spring clip 52 may be
disposed between a pair of pins 21 so that the arcuately
of adjacent magnetic elements jointly de?ning an air
gap therebetween; a pair of magnetic support members
each respectively secured to one end of said non-magnetic
base and each communicating magnetically with non-ad
formed end portions resiliently engage and electrically
jacent elements of said group of magnetic elements; and
75
connect the adjacent pins. The edges ‘formed at the
3,084,583
8
a permanent magnet having poles communicating mag
1,769,284
1,870,576
netically with each of said magnetic support members re
motely from said Wafer-like magnetic elements, so that
there is a single magnetic polarity induced by said perma~
17,915,858
nent magnet at each side of said gaps.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,576,545
Powers ______________ __ Mar. 16, 1926
10
Betz ________________ __ July 1, 1930
Knoblaugh ____________ _._ Aug. 9, 1932
2,239,985
2,252,708
Miessner ____________ __ June 27, 1933
Benio? ______________ __ Apr. 29, 1941
Douden _'__' ___________ __ Aug. 19, 1941
2,293,372
2,327,277
2,942,512
Vasilack ____________ __ Aug. 18, 1942
Lovell et a1. __________ __ Aug. 17, 1943
Miessner ____________ __ June 28, 196G
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