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Патент USA US3051932

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Aug. 28, 1962
M. E. BOURNS ETAL
3,051,921
VARIABLE RESISTOR GONSTRUCTIONS
Original Filed July 26, 1954
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3,051,921
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United States Patent O ” ICC
Patented Aug. 28, 1962
l
2
3,051,921
the sections 11 by means of insulating ledges 17 extend
ing along the sides 1S of the Sections 11 between the ends
19 of these sections. Electrical connections to the mem
ber 14 and the cylinder 15 are made `by means of conduc
VARIABLE RESISTÜR CGNÉTRUCTIUNS
Marlan E. Bottins, Wiibnr T. I-Iardison, and Warren i).
Hulbert, Riverside, Calif.; said Hardison and Hulbert
assignors to Bonrns, Inc., a corporation of Caiifornia
Original application July 26, 1954, Ser. No. 445,534, now
Patent No. 2,8S2,37È, dated Apr. 14, 1959. Divided
and this application Mar. 2, 1959, Ser. No. 809,331
6 Claims. (Cl. 33â--1S1D
tive terminals 20 which are each formed so as to have
a shank section 21 projecting through the ends 19 of the
sections 11. The terminals 20 include upstanding center
portions 22 positioned so as to lie against the internal sur
faces of the ends 19 and bent over contact sections 23
which are designed to engage either the member 14 or
the extremities of the cylinder 15 with a spring action so
as to at all times be in electrical contact with this member
14 and the film 16.
The present invention is concerned with new and im
proved variable resistor constructions, and is a division
of our co-pending application, Serial No. 445,534, tiled
A threaded metallic shaft 24 extending beyond the
Iuly 26, 1954, now Patent No. 2,882,375, for Variable
Resistor Constructions. More specifically it is concerned 15 sections 11 is held within semi-cylindrical depressions 25
in the ends 19 of the sections 11 so as to project generally
with extremely small resistors, although, obviously many
parallel to the ledges 1’7, the member 14 and the cylinder
of the constructional details herein described are capable
15. Adjacent to the exterior of these sections y11 the shaft
of being used on comparatively large electrical compo
24 «is provided with slots 26 which are engaged by in
nents of the class described. A broad object of the in
sulating caps 27 of a resin such as indicated above or like
vention is to provide new and improved variable resistor
material formed so as to encase the portions of shaft 24
constructions. A more specific object is to provide vari
projecting from the ends 19. These caps 27 are each
able resistors which are comparatively cheap to construct,
provided with slots 2S designed to be engaged with a screw
reliable in operation, and which can be manufactured in
very small size. Further areas or objects of this invention
driver so `that the shaft 24 can be turned.
A contact member 30 formed of a single strip of metal
will be apparent from the remainder of this specification. 25
bent so as to have a lirst side 31, a second side 32 attached
This invention may be summarized as being concerned
to said first side 3‘1 by a ñrst apex 33 and manufactured
with variable resistors each having an elongated housing,
so as to have aligned apertures 34 and 35 within the sides
preferably formed of `an insulating material within which
31 and 32 respectively, is placed between the sections 11
there is disposed at least one resistance member, another
electrically conductive member which may be a resistance 30 with the shaft projecting through the apertures 34 and
35. The exact shape of these apertures may be varied
member, a metallic contact member, and means for mov
within wide limits. Preferably however, they are of gen
ing this contact ‘member with respect to the resistance
erally oval shape so that as the sides 31 and 32 are pressed
member and the electrically conductive member, and from
toward one another the shaft 24 may be easily inserted
which housing there project appropriate electrical ter
minal members and said means for moving the metallic 35 through them and so that as these sides are released the
edges of the metal strip at the openings vwill be brought
contact member. The invention is more fully summarized
into engagement «with the shaft 24- because of the inherent
by the appended claims. Further details of the invention
resiliency of the material from which the contact member
are best apparent `from the balance of this specification,
31D is formed. Preferably at least one of the apertures 34
the appended claims, and the accompanying drawings, in
40 or 35 is formed so as to have edges which are designed
which:
in a conventional manner to engage the threads upon the
FIGURE l is a top view of a resistor of the invention;
shaft 24 so that as the shaft is turned the contact member
FIGURE 2 is a partial cross-sectional view taken at
319 is moved upon it. The portions of the shaft 24 im
line 2-2 of FIGURE l;
mediately adjacent to the sections 1I are preferably not
FiGURE 3 is a cross-sectional View taken at line 3_3
of FIGURE l;
FIGURE 4 is a View similar to F'IGURE 2 of a modi
íied construction of the invention;
45 threaded so that the contact member 30 Will upon con
tinued rotation of the shaft in either direction move sub
stantially off the threaded portion of the shaft and engage
the ends y19, causing this member to temporarily disengage
FIGURE 5 is a cross-sectional view taken at line 5-5
the threads on the shaft 24.
of FIGURE 4;
The contact «member 3G includes an end 36 attached
FIGURE 6 is a view similar to FIGURE 2 of a second 50
modiiied construction of the invention;
FIGURE 7 is a cross-sectional view taken at line 7-7
of FlGURE 6;
FIGURE 8 is an isometric view of a resistance member
v to the second side 32 by means of a second apex 37. This
apex y37 is designed to ride against the surface of the iilm
on cylinder 15 as the shaft 24 is turned. During such
motion the parts of the contact member 30 adjacent to the
FIGURE 9 is a View similar to FIGURE 3 of a third
55 ledges 17 engage these edges, preventing rotation of the
member 30. The contact member 30 also includes an at
modified construction of the invention.
The various items shown in the drawings have been
tached member 38 projecting from either of said sides 31
or 32 beyond said first apex 33. This member 3S in
which may be employed with the invention; and
cludes an upturned end 39 attached to it yby means of a
be more fully described. For this reason the majority 60 third apex 4t). This third apex 4i) is designed to engage
the member 14 so as to at all times be in electrical con
of parts shown in the various figures are not necessarily
tact with it. It is considered obvious from the drawings
to the scale of proposed commercial units embodying the
that the entire contact member 30 may be conveniently
constructions shown.
manufactured from a single piece of metal by a simple
In FIGURES l, 2 and 3 of the drawings there is shown
a variable resistor construction 1d which includes bi 65 stamping operation and that the apexes 37 and 40 are de
signed to be held against the member 14 and the film 16
laterally symmetrical shell-like sections 11 formed of
as indicated with a spring-like action resulting from the
an insulating «material such as a ñlled phenolic resin,
inherent resiliency of the material from which the con
which sections are secured together by rivets 12 so as
tact member 30 is manufactured.
to form a complete housing within which there is disposed
The assembly of the variable resistor construction 1d is
a conductive metallic member 14 and a cylinder 15 pro 70
exceedingly simple, and marks one of the major advan
vided with an external resistance iilm 16. Both the mem
tages of this specific construction. In manufacturing it
ber 14 and the cylinder 15 are held in position between
drawn so as to best illustrate particular features as will
3,051,921
3
one of the sections lll is placed upon a table or other sup
porting surafce and the various parts specifically indicated
in the preceding discussion are merely laid in position
upon it. The terminals ‘Ztl are inserted with slots ‘l2
formed in the section lll so as to be biased against the
conductive member with which they make contact before
position 5ft in the expected manner. When the iinal con
struction 56 is assembled the sections 5l and 52 are pref
erably secured together by an appropriate adhesive al
though other equivalent means may be used.
In FIGURES 6 and 7 of the drawing a second modified
construction 86 of the invention comprising a shell-like
section Sl of an insulatingr material defining together with
the other of the sections Il is applied to the unit. Simi
larly the contact member 30 is placed in substantially its
a lid 32 of a transparent insulating material such as those
ñnal position, and then as the other section Il is posi
marketed under the trademarks Lucite, Plexiglas, etc., a
tioned over the section Il. upon the supporting surface 10 complete housing having an internal cavity 83 is shown.
and all of the various parts are “trapped” in assembled
The lid S2 and the section til are normally secured to
relation. The construction i6 is completed by heading
gether by an adhesive or other equivalent means. Within
over the rivets l2 in an obvious manner. If desired,
the section 8l there is provided a resistance composition
other equivalent fastening means such as an adhesive can
S4 which may, like the composition 5d, be either posi
be employed instead of these rivets.
tioned within the supporting section Sl or be molded in
The modified construction 56 shown in FIGURES 4
situ within this section. Terminal connections are made
and 5 is composed of two shell-like sections 5l and 52;
to the composition 34 by means of electrically conductive
composed of an insulating material which are designed to
rivets 65 which are either molded within the section Sl
fit together in substantially the same manner as the sec
or are inserted within apertures in this section after it
tions ll. The section 5l is provided with a substantially
has been formed. Each of the rivets S5 is secured in
rectangular internal cavity 53, the bottom of which is
the obvious manner to small metal terminal tabs 66 posi
filled with a resistance composition 54 which may, if de
tioned upon the outside section 8l.
Located within an aperture S7 formed within an end
sired, be molded in situ, or may, if desired, be inserted
within the section 5l after this section has been formed.
3S of the section 3l so as to proiect from this end 3S into
Electrical contact can be made to this resistance com
position 54 by means of metallic terminals 55 including
exterior portions 56 designed to tit against the exterior
surface S7 of the section 5l, attached center portions S8
a. circular depressed cavity E66 formed within the other
end 88 of the section Sl is a conductive shaft 96 which
is threaded intermediate its ends and preferably has an
unthreaded end portion engaging the cavity 166, this
designed to ñt witln'n notches 59 formed within the sec
Unthreaded portion having a cross-sectional diameter
tion 5l, attached internal portions 6@ designed to engage 30 equal to or slightly smaller than the minor diameter of
the internal surface of the cavity 53 so as to form what
the threaded portion of the shaft 9d, such that the con
in effect may be considered a spring clip engaging the
tact lmember i655 may disengage the threaded portion of
section 5l and extending over the top thereof. The por
the shaft upon reaching the right-hand travel extremity,
tion 6l) is connected to an end 6I of bent configuration as
thereby preventing the breakage of the housing incident
illustrated in FIGURE 5 which is designed to engage 35 upon the turning of the shaft 9i) an excessive number of
the resistance composition 54 with a spring-like action
revolutions. rThe Contact member £65 is so constructed
so as to establish electrical contact therewith.
that spring pressure exerted by the end of the contact
The section S2 is also provided with a substantially
member E05 against the inside of the internal cavity 83
rectangular internal cavity 63 which, if desired, may be
causes the spring to again engage the threaded portion of
used to contain a non-conductive cylinder 64 provided
the shaft 90 when the shaft @il is turned in a reverse di->
with an external resistance coating 67. This cylinder 64
rection, causing the contact spring to move toward the
is designed to be held in place by means of metallic ter
left-hand end of the instrument. This shaft is secured
minals 65 including exterior portions 66 which are in
in position by means of a tab ltl'ï formed integrally with
tended to lit against the exterior surface of the section 5I.
the lid 82, projecting from this lid so as to engage a
These terminals 65 also includes center portions 68 which 45 groove 16S formed Within the shaft 9i?. This shaft is
are designed to fit within notches 69 formed within the
also secured to a non-conductive cap 92 externally of the
sections 52 and attached internal portions 62 lying against
section till by means of one or more non-conductive
the surface of the internal cavity 63. The terminals 65
pins 91; this cap 92 is provided with a slot 93 of the
each contain an end section 7@ bent the general shape of
conventional type designed to receive a screw driver.
the cylinder 64. As is illustrated in FIGURE 5 these sec 50 Electrical contact is made to the shaft 90 by means of
tions 76 are designed to engage the cylinder 64 with a
a metal terminal 95 including a portion 96 adapted to
spring-like action forming electrical contact with the re
lie along the outside of the section 3l, a center section 97
sistance coating 67. If desired, the ends 7@ may be pro
designed to fit within a notch 98 within this section 8l
vided with terminal extremities 71 which are designed to
and a portion 99 designed to ñt against the internal sur
engage a surface of the cavity 63 remote from the surface 55 face of the section 8l in such a manner that the entire
of this cavity engaged by the internal portions 62 so as
terminal 95 is held in position with a spring or clip-like
to firmly hold the terminals 65 in position within the
action. The portion 99 of the terminal 95 is provided
section 52 by a spring-like action.
with an end section I0@ which is normally biased by a
Within the construction 56 there is provided a metallic
spring-action, resulting from the inherent resiliency of
contact member '75 of substantially the same construction 60 the material from which the terminal 95 is manufactured,
as the contact member 3i) shown in FIGURES 2 and 3
against a cyilndrical section ltil of the shaft 90 so as to
of the drawing. Because of the similarity of construc
be in electrical contact with this shaft as it is turned.
tional details between the two contact members like parts
The shaft 90 carries a contact member 165 of substan
of each are designated by the same numerals. The con
tially the same construction as the contact member 30
tact member 75 is carried by an elongated shaft 76 formed 65 except for the omission of the attached member 33 pro
of an insulating material so as to be threaded in the same
jecting from the contact member 36. Because of the simi
manner as the shaft 24. This shaft 76 is designed to pro
larity of construction details the same numbers are used
ject from both ends of the construction 5t) through de
to designate parts of the contact member 165 as are used
pressions 77 of substantially semi-circular configuration
to designate equivalent parts of the contact member 30.
formed in the sections 5l and 52, and is designed to be 70 One important feature 'of the speciñc construction
held in place by collars 7S formed on the shaft 76 bearing
shown in FIGURES 6 and 7 of the drawings relates
against the surfaces of the cavities 53 and 63. With this
to the fact that the position of the contact member 105
specific construction the member 76 may be turned caus
within the construction 80 is readily visible through the
ing the appropriate parts on the contact member 75 to
lid 82. If desired, various markings may be applied to
engage the resistance coating 67 and the resistance com 75 this lid 82, which correspond to the position of the apex
3,051,921
5
5
33 of the contact member 105 or to other parts of the
contact member so that at all times it is possible to
other related resistor constructions. The resistors herein
described are specifically intended to be manufactured
accurately determine the position of the contact member
having `a cross-section size of approximately lÁs by 1A
inch.
within the construction 80.
In FIGURE 9 of the drawings there is shown a variable
resistor construction 110 which differs from construction
80 shown in FIGURES 6 and 7 in only several minor re
gards. This specific construction 116 involves the use of
scope `of this invention.
a non-conductive lid 111 to which there is secured either
by means of an adhesive or by metallizing techniques a
thin layer of a conductive metal 112. This lid is used
category which are within the skill of the art are to be
considered as part of this invention.
We claim:
to cover a shell-like section 113 formed of an insulating
material so as to define an internal cavity, and is secured
to this shell-like section by means of an adhesive or like
means in such a manner that the layer 112 faces this
including: an elongate insulative housing having sides
and opposed ends; a resistance member disposed within
Those skilled in the art will realize that a number of
minor modifications may be made within the precise con
structional details indicated without departing from the
All such modifications of this
l. A new and improved variable resistor construction
said housing adjacent to one of said sides; an electrically
internal cavity 114, This cavi-ty is of such dimension
conductive screw-threaded shaft positioned principally
as to easily hold a shaft 116 which carries a contact mem
within said housing and having an end disposed so as to
be accessible from the outside of at least one of the ends
ber (not shown). Both the shaft and the contact mem
ber employed with this embodiment of the invention are
of the housing; a reversely bent metallic conductive
substantially identical to the equivalent members employed
spring contact member having opposed apertured por
tions, disposed within said housing in engagement with
in the construction 80 illustrated in FIGURES 6 and 7.
The contact member employed in the embodiment of
FIGURE 9 is adapted to move against a wound resistance
unit of a type specifically illustrated in FIGURE 8 of the
drawings as including a generally oval cross-sectioned
said shaft and with lthe shaft extending through the aper
tures so as to be moved by rotation of the shaft, the
contact member being in electrical contact with said re
sistance member; a spring metal terminal strip extending
through and embedded in one side `of said housing adja
elongated body 11S of lan insulating material around which
cent an end thereof, said terminal strip extending trans
there are positioned a number of turns 119 of a resistance
versely of said housing and resiliently bearing against
wire. These turns 119 `are of the conventional category
the side of said shaft so as to make electrical Contact
employed in wire-wound resistors and are connected at
one end of the body 118 to `a large mass or group of 30 therewith; and terminal means each attached to `a respec
tive end portion of said resistance member and projecting
turns 120 of the same resistance wire. The unit 115 is
designed so that the contact member employed is intended
through said housing.
2. A variable resistor comprising: an elongate hous
ing formed of an electrically non-conductive material
pled with what in effect amounts to a very tine adjust 35 and having sides and opposed ends; an elongate resistance
element disposed within said housing adjacent one of said
ment of the resistance by the use of the turns 119.
sides; an electrically conductive screw-threaded shaft ro
The resistance unit 11S employed in the construction
tatably supported by said housing parallel to said resist
110 is normally held in position by means of spring clips
ance element, one end of said shaft projecting outwardly
121 having opposed bowed sides 122 positioned against
to make contact with the turns 119. With this construc
»tion the turns 120 provide a large resistance value cou
opposed sides of the cavity 114 in such a manner that 40 through an aperture in one of said ends of said housing;
a head of non-conductive material iixed to said one end
these sides engage the resistance unit 11S when this unit
of said shaft, said head being formed to receive an ad
is inserted within the cavity 114 so as to hold it firmly
in place. The spring clips used are disposed at opposite
ends of the cavity 114 in such a manner that they make
contact with the portions of the windings or turns 119
and 120 farthest removed from one another. Both of
these spring clips 121 are provided with bottom walls 123
justing tool; a reversely bent spring contact member having
opposed apertures through which said shaft extends and
Which member .is operatively engaged at two spaced-apart
locations by the thread of said lead--screw so as to be
moved thereby along the shaft, said contact member
wiping on said resistance element and making an elec
co-nnected to the sides 122. These bottom walls 123 are so
trical connection with said shaft; and a spring metal ter
designed as to pass together outwardly through an appro
priate aperture (not shown) Within the section 113 in a 50 minal strip extending through and embedded in one side
conventional manner.
of said housing, said terminal strip extending transversely
the bottom of this section adjacent to the spring clips 121
said resistor comprising:
of said housing and resiliently bearing against the side of
With the construction 110 electrical contact is made
said shaft so as to make electrical contact therewith, and
to the layer 112 -by means of a terminal 125 whic
other terminal means connected to said resistance element.
embedded within the walls of the section 113 as indicated
3. A variable resistor of the leads screw-actuated type,
in FIGURE 9 of the drawing so as to project from both 55
and so as to project from the walls of «the section 113
into the internal cavity 114 adjacent to the top of this
cavity. There the terminal 125 is provided with an end
126 which is adapted to be held against the layer 112 60
by spring tension so as to be in electrical contact with
this layer.
longitudinal Walls;
second means, comprising elongate resistance element
means secured in said housing, and terminal means
The various variable resistor constructions illustrated in
the accompanying drawings and described in the afore
going discussion constitute a very distinct advance in the 65
art in that they are all extremely reliable in operation
and yet are extremely simple to easily and cheaply pro
duce on a production line basis.
h
first means, including an elongate housing means pre
senting an electrically insulative exterior surface and
opposed end-Wall means interconnected by elongate
Further, many of the
operative parts of the resistor constructions described,
such as, for example, the contact members indicated, may 70
be easily and cheaply fabricated and are exceedingly re
liable for use with other constructions besides those spe
ciñcally indicated. Inasmuch as all of the resistors shown
employ housings which are non-conductive, these resistors
are immune from shorting troubles which have plagued 75
for said element extending to the exterior of said
housing;
-
third means, comprising elongate electrically conductive
screw-threaded shaft means journaled at opposite
ends thereof in said opposed end-wall means, said
third means including electrically insulative means
engaging one end of said shaft and constructed and
arranged for rotating said shaft;
fourth means, comprising essentially a conductive spring
contact having two portions encircling said shaft and
engaging the latter to be driven by the shaft upon
rotation of the shaft, said contact being constructed
3,051,921
„7
d
and arranged to wipe said resistance element and elec
trically interconnect the contact and said shaft;
and fifth means, comprising a spring terminal element
embedded in and extending through a wall of said
housing means, said terminal element having a
resilient extension in said housing conductively con
tacting said shaft means.
4. A variable resistor of the type wherein a linearly
6. A variable resistor according to claim 4, further char
acterized by the conductive spring-contact having integral
opposed apertured limbs disposed at an acute angle each to
the other and by the screw-threaded shaft extending
through the apertures in the limbs of the Contact, and fur
ther characterized by the screw-threaded shaft having
threadless opposite end-portions separated by a threaded
portion, whereby upon continued rotation of the shaft in
either direction of rotation the contact moves susbtantially
along an extent of an elongate terminated resistance ele 10 otî the threaded portion of the shaft and onto a threadless
ment by rotation of a screw-threaded shaft that is arranged
portion to limit linear motion of the contact along the
substantially parallel to the resistance element and the
resistance element.
movable conductive spring-contact is moved longitudinally
resistance element is disposed in a molded insulative hous
ing, characterized by a resilient electrically conductive ter
minal element extending outwardly from and embedded in 15
and supported by the housing and pressing against a por~
tion of the shaft, whereby the resistance element is electri
cally connected to the terminal by way of the spring-con
tact and the shaft.
5. A variable resistor according to claim 4, further char 20
acterized by the screw-threaded shaft having a threadless
portion adjacent one end thereof, upon which threadless
portion the conductive terminal presses.
References Cited in the tile of this patent
UNTTED STATES PATENTS
1,668,117
Kent _________________ __ May 1, 1928
1,673,443
1,955,906
2,687,463
2,745,054
2,912,663
2,932,808
Crosley ______________ __ June 12,
Crouse ______________ __ Apr. 24,
Riley ________________ __ Aug. 24,
Leyenberger ___________ __ May 8,
Van Allen ___________ __ Nov. 10,
Bourns et al ___________ __ Apr. 12,
1928
1934
1954
1956
1959
1960
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