U.S. patent number 3,699,492 [Application Number 05/196,909] was granted by the patent office on 1972-10-17 for variable resistance device for a portamento performance on an electronic musical instrument.
This patent grant is currently assigned to Nippon Gakki Seizo Kabushiki Kaisha. Invention is credited to Kenji Yoshihara.
United States Patent |
3,699,492 |
Yoshihara |
October 17, 1972 |
VARIABLE RESISTANCE DEVICE FOR A PORTAMENTO PERFORMANCE ON AN
ELECTRONIC MUSICAL INSTRUMENT
Abstract
A variable resistance device for a portamento performance on an
electronic musical instrument wherein a conductive coiled spring is
held by a supporting member and an elongate resistor is so held by
the supporting member as to face the coiled spring at a small
space. The elongate resistor is used to determine the output
frequency of a tone signal generator. Depression of the coiled
spring with player's finger causes it locally to contact the
resistor, and the continuous shift of the player's finger
successively varies resistance across the coiled spring and
resistor, thereby providing a portamento performance.
Inventors: |
Yoshihara; Kenji (Hamamatsu,
JA) |
Assignee: |
Nippon Gakki Seizo Kabushiki
Kaisha (Hamamatsu-shi, JA)
|
Family
ID: |
27284562 |
Appl.
No.: |
05/196,909 |
Filed: |
November 9, 1971 |
Foreign Application Priority Data
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|
|
|
|
Nov 16, 1970 [JA] |
|
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45/113487 |
Apr 2, 1971 [JA] |
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46/24223 |
Nov 25, 1970 [JA] |
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45/103460 |
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Current U.S.
Class: |
338/69; 84/704;
84/DIG.7; 338/96; 984/321 |
Current CPC
Class: |
H01C
10/00 (20130101); G10H 1/0558 (20130101); Y10S
84/07 (20130101) |
Current International
Class: |
H01C
10/00 (20060101); G10H 1/055 (20060101); H01c
009/00 () |
Field of
Search: |
;338/69,47,96,92,154
;84/1.24,DIG.7,1.01,1.17 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myers; Lewis H.
Assistant Examiner: Tone; D. A.
Claims
What is claimed is:
1. A variable resistance device used in a tone signal generator for
a portamento performance comprising:
a coiled spring member;
an elongate resistor member used as an element for determinging the
output frequency of said tone signal generator; and
supporting means of electrically insulating material for holding
said coiled spring member and elongate resistor member in mutually
facing relationship at a predetermined space;
said coiled spring member being movable toward said resistor member
by the depression of said coiled spring.
2. A variable resistance device according to claim 1 wherein said
supporting means is provided with first and second components each
having a notched portion, the notched portions of said components
facing each other with a predetermined space formed therebetween;
and said coiled spring, subjected to deformation against the
elasticity of said spring, is inserted in said space so that the
exertion of a force on said coiled spring permits further
deformation of said coiled spring, enabling said coiled spring to
move toward said resistor member.
3. A variable resistance device according to claim 2 wherein said
coiled spring member consists of turns of wire forming an open
space therein, said open space being filled with flexible
material.
4. A variable resistance device according to claim 2 wherein said
coiled spring has a portion thereof projecting outward from said
space formed between said notched portions of said supporting
components.
5. A variable resistance device according to claim 1 wherein said
supporting member consists of an elastic insulating material and
has a substantially cylindrical space and a further space
communicating with said substantially cylindrical space; and said
coiled spring is inserted in said substantially cylindrical space,
said supporting member being deformable against the elasticity of
said supporting member under a force acting thereon, whereby said
coiled spring is brought into contact with said resistor
member.
6. A variable resistance device according to claim 1 further
comprising an elastic conductive contact plate with a plurality of
ribbon-shaped electrically insulating films coated thereon, said
contact plate being disposed between said coiled spring and
resistor member by laminating said contact plate on said resistor
member, said contact plate and resistor member being spaced apart
from each other by the thickness of said insulating films.
7. A variable resistance device according to claim 6 wherein said
insulating films are coated on said conductive contact plate along
both lengthwise edges.
8. A variable resistance device according to claim 6 wherein said
insulating films are deposited on said conductive contact plate at
a predetermined space at right angles to the lengthwise direction
of said contact plate.
9. A variable resistance device according to claim 6 wherein said
insulating films are spatially formed on said conductive contact
plate so as to extend slantwise from one lengthwise edge to the
other of said plate at a predetermined angle to its transverse
direction.
10. A variable resistance device according to claim 1 wherein said
supporting means is provided with first and second components each
having a notched portions, the notched portions of said components
facing each other with a predetermined space formed therebetween;
and said coiled spring consisting of turns of wire is inserted in
said space with each of said turns directed obliquely to the
lengthwise direction of said coiled spring, said obliquely directed
turns being subjected to deformations against the elasticity of
said coiled spring, whereby, when a force is applied to said coiled
spring to move said coiled spring toward said resistor member, said
coiled spring is further deformed with the obliquity of said turns
increased and is permitted to travel toward said resistor member.
Description
BACKGROUND OF THE INVENTION
This invention relates to an electronic musical instrument and more
particularly to a variable resistor device adapted for a portamento
performance thereon.
With the prior art electronic musical instrument, or electronic
organ, there was imitatingly obtained a portamento effect by the
glissando performance in which the finger was slidingly moved along
the keyboard in the direction in which the keys were arranged.
The portamento effect results from successive variations in the
frequency of sound waves. Therefore, the portamento effect in the
truest sense of the word can be realized, in the case of an
electronic musical instrument, by forming a tone signal generator
from a variable frequency oscillator and using a variable
resistance device as an element for determining the frequency of
the oscillator and successively varying the resistance of the
device so as to obtain a continuously changing oscillating
frequency.
A variable resistance device for generating such a portamento
effect is required to be of such type as allows the player to vary
the magnitude of resistance easily by a single hand.
The prior art variable resistor device comprises a elongate
resistor member, a supporting member for holding the elongate
resistor member and a flexible sheet-like conductive contact member
so secured by the supporting member as to face the narrow resistor
member at a small space and provided with a large number of slits
disposed at right angles to the length-wise direction of the
elongate resistor member.
When depressed by player's finger, the flexible sheet-like
conductive contact member locally touches the elongate resistor
member by the action of the slits. When the finger continuously
slide on the contact member lengthwise of the resistor, there
result successive variations in the resistance across the resistor
and the contact member. If, in this case, the resistor and
conductive member are so arranged as to effect contact therebetween
as locally as possible, then there will be realized a portamento or
melody performance smoothly and distinctly. With the aforesaid
resistor device, the local contact between the resistor and
conductive member is carried out by the action of the slits,
requiring the conductive portions exposed between the adjacent
slits to be as narrow as possible. However, such demand presents
difficulties in manufacturing the conductive contact member and
miniaturizing of the overall variable resistor device. Further,
after local contact with the resistor, the conductive member has to
be quickly brought back to its original state. However, the
conventional resistor device does not easily permit the rapid
return of the conductive member.
SUMMARY OF THE INVENTION
It is accordingly the object of this invention to provide a
variable resistance device for a portamento performance on an
electronic musical instrument which enables a conductive member
locally to contact a resistor and thereafter quickly return to its
original state and further simplifies the manufacture of its parts
and realizes the assembly thereof in a compact compact form.
According to this invention, a coiled spring is used as a
conductive member contacting the elongate resistor member or as an
actuating member for bringing a conductive contact member in
contact with the resistor member. In an embodiment of the
invention, the coiled spring is forcefully deformed or twisted
against its elasticity so as to present a vertically elliptic
shape. The shorter diameter section of the coiled spring is held
between the notched portions of first and second supporting members
of insulating material so as to have its upper end project from the
supporting members. The first and second supporting members further
have a groove formed below the notched portions. Into these grooves
are inserted both lengthwise edges of the elongate resistor member
so as to face the coiled spring at a small space. When the upper
part of the coiled spring slightly projecting upward from the first
and second supporting members is depressed with player's finger,
part of the turns of the coiled spring contacts the resistor
member. Upon release of the finger, the part of the turns is
quickly brought back to its original state due to the elastic
restoring force of the forcefully deformed spring. Thus the
elasticity of the spring enables the resistor to vary its value in
succession smoothly and minutely. Use of a coiled spring as a
conductive member simplifies the manufacture of the parts of a
variable resistor device and realizes the assembly thereof in a
fully compact form.
According to another embodiment of the invention, the supporting
member for holding the coiled spring and resistor is formed by
resilient insulating material. Further there are provided a
cylindrical space for receiving the coiled spring and a groove
below the space for supporting the elongate resistor member. The
coiled spring is inserted into the cylindrical space and, when
depressed with player's finger, is brought into contact with the
elongate resistor member through the upper surface of the resilient
supporting member.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, partly in section, of a variable
resistor device according to an embodiment of this invention;
FIG. 2A represents the top surface of a coiled spring subjected to
a certain deformation and used as a conductive contact member in
the resistor device of FIG. 1;
FIG. 2B is a side view of the coiled spring shown in FIG. 1 as
taken in the direction of an arrow X in FIG. 2A;
FIG. 2C represents the top surface of the coiled spring, some turns
of which are further deformed;
FIG. 3 is a perspective view, partly in section, of a variable
resistor device according to another embodiment of the
invention;
FIG. 4 is a modification of FIG. 3;
FIGS. 5A, 5B and 5C indicate the different forms in which there is
coated an insulating film on the contact plate used in FIG. 4;
FIG. 6 schematically illustrates, partly in section, the manner in
which there is fitted the resistor device of FIG. 3 to an
electronic musical instrument;
FIG. 7 is a perspective view of an electronic musical instrument in
which there is incorporated the variable resistance device of the
invention; and
FIG. 8 shows a schematic circuit arrangement of an electronic
musical instrument including a variable frequency tone signal
generator provided with the variable resistance device of the
invention as an element for determining the frequency of tone
signals produced by the generator.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, reference numeral 1 denotes a coiled spring
consisting of many turns of electrically conductive wire prepared
by plating gold on, for example, nickel-silver, phosphor bronze, or
piano wire. The coiled spring 1 is forcefully deformed or twisted
against its elasticity with two forces F.sub.1 and F.sub.2 acting
in opposite directions applied to both sides of the coiled spring 1
along the entire length thereof, thereby presenting an elliptic
shape, as shown in FIG. 2B, when viewed in the direction of an
arrow X in FIG. 2A. Thus, the coiled spring 1 is so formed as to
have shorter diameter section 1a and a longer diameter section 1b,
as indicated in FIG. 2B. The elliptically deformed coiled spring 1
is inserted in a long space formed between a first and a second
elongated supporting members 2 and 3 made of electrically
insulating rigid material such as hard rubber or synthetic resin,
with its shorter diameter section supported between the mutually
facing V-shaped notched portions 4 and 5 of the first and second
supporting members 2 and 3. That is, the coiled spring 1 is
inserted in the space formed by the V-shaped notched portions 4 and
5 with each turn of the coiled spring 1 directed obliquely to the
lengthwise direction of the coiled spring 1, the obliquely directed
turns being subjected to deformation against the elasticity of said
coiled spring. In this case, the upper end of the larger diameter
section of the coiled spring 1 is held by the first and second
supporting members 2 and 3 so as slightly to project therefrom. In
any case, the coiled spring thus deformed is held in the space
formed by the V-shaped notched portions 4 and 5 and is kept from
coming out of the space spontaneously as long as it is not
subjected to a further deformation. The first and second supporting
members 2 and 3 further have mutually facing grooves 6 and 7 formed
below the respective notched portions 4 and 5. Into the grooves are
inserted both lengthwise edges of a elongate resistor member 8. The
space formed between the V-shaped notched portions 4 and 5 is
communicated with the grooves 6 and 7 through an open space 13
somewhat narrower than the space between the notched portions 4 and
5.
The first and second supporting members 2 and 3 are held in
position by a box-like frame 9. From below the resistor 8 are drawn
out a number of conductive terminals (taps) 10 (only one is shown)
through openings formed in the frame 9. The hollow space of the
coiled spring 1 is filled with a flexible material 11 such as a
soft polyurethane foam, but the material 11 may be eliminated.
When, in the variable resistance device of the aforementioned
arrangement, there is depressed with player's finger the upper part
of the coiled spring 1 projecting upward from the first and second
supporting members 2 and 3, the depressed part of the turns of the
coiled spring 1 is further deformed or twisted against its
elasticity, as shown in FIG. 2C, with the depressed part of the
turns increasing its obliquity and presenting a narrower elliptic
shape than that shown in FIG. 2B, and comes down into the open
space 13 until it is brought into contact with the resistor 8.
Accordingly, there results across the coiled spring 1 and the
conductive terminal 10 provided on the resistor 8 such a degree of
resistance as corresponds to that part of the coiled spring 1 which
contacted the resistor 8. There is produced by the tone signal
generator a tone signal having a frequency corresponding to the
degree of resistance. The circuit of the tone generator will be
later described. When the depressed point on the coiled spring 1 is
continuously shifted in its lengthwise direction, there are
obtained tone signals from the tone generator whose frequencies
successively vary.
Since the coiled spring 1 is deformed against its resiliency,
release of a force with which the player's finger depress it causes
it quickly to return to its original state due to the elastic
restoring force of the coiled spring. The coiled spring 1 contacts
the resistor 8 only at that part of its turns which is depressed,
so that the resistance of the variable resistor device which
determines the frequency of tone signals produced by the tone
generator can be set very accurately.
The variable resistance device of this invention is prepared simply
by disposing the coiled spring 1 and resistor 8 between the first
and second supporting members 2 and 3 held by the frame 7,
extremely facilitating the manufacture of these parts and their
assembly. In this case, the coiled spring 1 is held between the
first and second supporting members 2 and 3 with its turns
forcefully deformed so as to present an elliptic shape due to
forces acting lengthwise of the coiled spring 1 in opposite
directions. Accordingly, it is securely set in place by its elastic
restoring force.
The coiled spring 1 used in the aforementioned embodiment
preferably consists of one prepared by winding a wire of about 0.3
to 0.6 mm thick to form a coil of many turns each having a diameter
of 4 to 8 mm, thus rendering the resultant variable resistance
device fully compact as a whole. The coiled spring 1 has only to be
spaced 0.5 to 2 mm from the resistor 8. If the hollow space of the
coiled spring 1 is filled with the very soft flexible material 11,
it will help in prevention of dust from entering into the space 13
and being deposited on the resistor 8. It is further possible to
cover the upper part of the variable resistance device with a
protective cover 12 which is pliant and little subject to expansion
and contraction such as piled cloth or that of Teflon.
There will now be described by reference to FIG. 3 a variable
resistance device according to another embodiment of the invention.
In FIG. 3, the supporting member 20 consists of elastic insulating
material, for example, rubber or soft polyvinyl chloride and
contains a cylindrical space 21 and a rectangular space 22
communicating therewith. That section 23 of the supporting member
20 which defines the cylindrical space 21 is formed with a thin
wall and upwardly projects in a substantially semicircular shape.
The other sections 24 and 25 of the supporting member 20 which face
each other across the rectangular space 22 are provided with
grooves 26 and 27 respectively.
The coiled spring 1 is inserted into the cylindrical space 21 of
the supporting member 20, and the resistor 8 has both lengthwise
edges fitted into the grooves 26 and 27. Below the resistor 8 is
disposed the conductive terminal 10. According to the embodiment of
FIG. 3, the coiled spring 1 is inserted into the cylindrical space
21 without being deformed or twisted at all, differing from the
above-mentioned embodiment.
With a variable resistance device of the above-mentioned
arrangement, vertical depression of the thin-walled semicircular
projection 23 of the supporting member 20 in the direction of an
arrow P in FIG. 3 causes the supporting member 20 to be deformed,
bringing the coiled spring 1 into contact with the resistor 8.
According to this embodiment, depression of the semicircular
projection 23 slantwise from above as indicated by arrows P' and P"
also enables the coiled spring 1 fully to touch the resistor 8. As
in the preceding case, the semicircular projection 23 may be
surrounded with a protective cover.
In the two foregoing embodiments, the coiled spring 1 should
preferably have its turns of wire plated with gold so as to be
concurrently used as a conductive contact member. Since, however,
the plating of precious metals is expensive, there is presented in
FIG. 4 a modification of FIG. 3 to reduce the manufacturing
cost.
Referring to FIG. 4, there are inserted into the grooves 26 and 27
of the supporting member 20 both lengthwise edges of a laminated
layer consisting of the resistor 8 and an elastic conductive
contact plate 29 of nickel-silver about 0.05 mm thick. One side of
the contact plate 29 is coated by screen printing or spraying
ribbon-shaped insulating films 30, as illustrated in FIG. 5A, along
both lengthwise edges of the contact plate 29, or as shown in FIG.
5B, at a predetermined space at right angles to the lengthwise
direction of the contact plate 29, or as indicated in FIG. 5C, in a
spaced form slantwise extending at a predetermined angle to the
transverse direction of the contact plate from one lengthwise edge
to the other thereof.
Since the aforementioned insulating film 30 is about 0.01 to 0.05
mm, the contact plate 29 and resistor 8 face each other at a space
of 0.01 to 0.05 mm. In FIGS. 5B and 5C, the ribbon-shaped
insulating films 30 should be about 0.5 to 2 mm wide and should
preferably be spaced about 0.5 to 1 mm from each other.
According to FIG. 4, the contact plate 29 replaces the coiled
spring 1 of the preceding embodiments for use as a conductive
element. When the contact plate 29 is depressed with player's
finger through the coiled spring 1, those sections thereof which
are exposed between the adjacent insulating films 30 are brought
into contact with the resistor 8. Thus there takes place between
the contact plate 29 and resistor 8 such a degree of resistance as
corresponds to the contact point.
FIGS. 6 and 7 represent the manner in which the variable resistance
device of this invention is incorporated in an electronic musical
instrument. Reference numeral 41 denotes an inclined panel disposed
between a control panel 42 and a keyboard 43 of an electronic
musical instrument 40. The variable resistance device is held by a
supporting member 44 so as to have its operating section 23 project
from the aforesaid inclined panel 41. The variable resistance
device of this invention is so compact that it can be disposed in
any place where the player can easily operate it.
There will now be briefly described by reference to FIG. 8 the
circuit of a variable frequency oscillator for a portamento
performance using the aforementioned variable resistance device.
The indicated oscillator is a Wien bridge oscillator which
comprises an amplifier 50 including transistors Tr.sub.1 and
Tr.sub.2, the circuits 51, 52, 53 and 54 of a frequency determining
element connected parallel between the collector and emitter of the
transistor Tr.sub. 2, each of which consists of a series circuit
consisting of a resistor and capacitor connected in series with a
parallel circuit including another resistor and capacitor and
differs in phase shifting characteristics, emitter follower type
impedance converters 55, 56, 57 and 58, each of which is supplied
with signals from the junction of the aforesaid series and parallel
circuits consisting of resistors and capacitors, a resistance
element 59 provided with taps 10 connected to the emitter of the
respective transistors included in the impedance converts 55, 56,
57 and 58 and a conductor 60 constituted by the coiled spring of
the variable resistance device which is to be brought into contact
with the resistance element 59. The conductor is connected to the
transistor TR.sub.1 of the amplifier circuit through a separate
capacitor, thereby forming a feed back circuit.
The aforesaid circuits 51, 52, 53 and 54 of a frequency determining
element have frequencies which successively differ from each other,
for example, by one octave. Accordingly, frequency variation by
three octaves is available in the embodiment shown in FIG. 8. Since
there is not formed a feed back circuit unless the resistance
element 59 and conductor 60 contact each other, it will be apparent
that the aforementioned oscillator is not normally brought to an
operable state. Where the conductor 60 contacts the element 59
between the taps of the element 59 connected to the emitter of each
of the impedance transducer circuits 55 and 56, the oscillator
oscillates at a frequency having a magnitude intermediate between
those of the specific frequencies of the two circuits 51 and 52 of
the frequency determining element which are located nearest to the
contact point between the conductor 60 and element 59. Shifting of
the contact point results in the sequential change of the
oscillator frequency. Outputs from the oscillator are drawn out of
the emitter of the transistor Tr.sub.2 included in the amplifier 50
and supplied to a loud-speaker 61 through a tone coloring circuit
62 and another amplifier 63. If the conductor plate 60 is
intermittently depressed by the finger for contact with the
resistance element 59, then there will be realized not only a
portamento performance, but also other performances.
The oscillator shown in FIG. 8 represents a sine wave generator
including a capacitor and resistor. However, the variable
resistance device of the present invention is also applicable in
varying the frequency of a square wave generator such as an astable
multivibrator. In such case, there is connected a variable
impedance element such as a field effect transistor in series to
the stationary resistor constituting an element for determining the
frequency of the astable multivibrator. And there is impressed a
predetermined D.C. voltage across both ends of the resistance
element of the variable resistance device of the present invention,
and the conductor facing the resistance element is connected to the
gate electrode of the field effect transistor. Then the device acts
as a voltage divider to supply to gate electrode of the field
effect transistor with successively varying D.C. voltage with the
resultant change in the impedance of the field effect transistor,
causing the frequency of the astable multivibrator to be
continuously altered. Also in this case, the oscillator remains
unoperable, so long as the conductor does not contact the
resistance element.
* * * * *