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Патент USA US2407545

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Sept. 10, 1946.
Original Filed Aug. 16‘ 1943
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Patented Sept. 10, 1946
: ..'Fischer,.H1ghland
Park, Mich
All’gli‘égieral Motors Corporation, Detro1t,l\l1ch.,
a corporation of Delaware
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" " 'l'No'.
lic'ation August 16, 1§)43,_Ser1a
p'g?v‘ideii and this ‘application August
4 Claims. (Cl. 201—56)
This invention relates to variable electrical re
sistance means and
resistance meansin
in in?nitely small 7 ‘
the exterior face of this tube is mounted a'icylin- .
der I30 of Micarta or similar insulating material
which is relatively thick. In the exterior surface
of this member there is provided a spiral groove
titled “Recording mechanism.”
The use of resistance in electric circuits whose
value can be varied is very wide ‘spread. vOne
of the common forms of Variable resistance'which
I32 which extends substantially the full length of
the member thus forming between the grooves
a spiral raised surface. A pair of ‘parallel spaced
conductors I34 and I36 are wound upon this
surface and in similar spiral manner extend the
is used particularly in laboratory or research in
struments is the slide wire type ‘in which a length 10 full length of this insulating material. The op
of resistance wire is wound upon a cylinder and
posite ends of one of these conductors is brought
out through the insulated bushings I38 and I40
and the end of the other conductor is likewise
brought out ‘through the insulated bushing I 48,
15 thus forming three terminals to be connected to
Rotatably mounted below and slightly to the
rear of this tube is a long shaft I42 having axi~
fore changes as the contact is moved axially by
ally extending teeth for substantially its full
the value of one complete turn :at a ‘time. This
in some instances may .be entirely a too rough a 20 length, this shaft is trunnioned in the side walls
of the frame I2 extending through the left hand
variation to be used "in particularly sensitive re
wall to provide a smaller shaft section I44 upon
cording means or other ‘similar constructions.
which is mounted a spur gear I46. This engages
It is therefore an object of my invention to
a small driving pinion I48 mounted on a shaft
1 I50 of a reversible drive control motor
Therefore, when the'motor I52 is energized, shaft
I42 is rotated, and since the motor is reversible,
this rotation may take place in either direction.
A short cylindrical sleeve ‘member [54 having
inwardly projecting teeth I55 on its inner sur
is shown in Figure 1 a casing 2 housing a re
face, said teeth ‘being of spiral con?guration, is
?tted over the insulatingMi‘carta vtube I3!) and is
adapted to move axially along the same. There~
fore, if ‘the sleeve ‘is rotated the ‘projecting teeth
which engage the spiral groove I32 in the micarta
tube will ‘cause the cylindrical member I54 to
move along axially and assume the character of
a travelling nut. Upon the outer surface of the
cylindrical member I54 there is provided an in—
40 tegral set of spur gear teeth I58 which are adapt
ed to mesh with the long axial teeth of the r0
tatable member I42 to cause the member I54 to
rotate about the axis of the tube I24. Spaced
supporting members I60 and I62 engage the op
posite ends of the cylindrical member I54 and
provide bearing means for the sleeve. These
spaced members are held in proper position by
spacer means I64 secured thereto by screws I66.
Thus the member I54 may rotate within the
cording mechanism as above described. The vari
v 7 frame so formed about the surface of the Micarta
With these and other objects in View, which
will become apparent as the
the accompanying drawing, in which:
Figure 1 is a sectional view through a‘ recording
mechanism in which my invention is incorpo
Figure 2 is an enlarged View partially in section
showing the variable resistance of my invention.
Figure 3 is a View similar to Figure 2 show
ing a modi?ed form of my invention.
As mentioned above, one of the constructions
in which a very sensitive variable resistance is
necessary might be that of a temperature re
corder such as shown in the application above
mentioned, of which this is a division and there
it does so causes axially move
ment of the sleeve along the tube. The ends of
regard to the frame by means of two insulating
plates I26 and I28 at the opposite ends. Upon 5
the members I60 and I62 project downwardly
and are adapted to contact a cross bar I68 to
prevent the whole assembly from turning around
the axis of the shaft when the gear l58 is driven.
formed of insulating material having a spiral
groove in its external surface, a pair of spaced
conductors having resistance to current flow
Recording means such as a stylus I'M is provide
on the carriage in this instance for recording
wound on the surface of the member between
the grooved portions, means encircling a portion
_of_ the cylindrical member having projecting teeth
opening, which opening is spaced between
of the projecting teeth l5?
Into this openin-v '
threaded a short hollow Micarta cup 152 ha
inside a small compressed spring if
against a contact ball I36 forcin
it down into
cent wires
I35 thus
gar» be
tween the two and causing a conductive connec
tion at this point. As previously mentioned. one
of the wires is utilized as a resistor in a measur~
ing circuit and the other wire being uti '
conductor from the
that extend into the groove, means for movably
and rotatably mounting the last named means
whereby as he latter is rotated it will move axially
along the surface of the cylindrical member, and
conductive means mounted on the rotatable
means to bridge the gap between the two con
I ductors at a point as the rotatable means moves
along the member.
2. In resistance means, a stationed-v ovl‘h'l '
-member for? ‘f, 13,, 'rJAlic‘lUal surface, a pail’ of
spaced conductors spirally wound on the surface
of the member between the grooves, means ro
'e' ore, if the ball or con
1 s along the full length of the resistance
tatably mounted on themernbcr havine project~
wire we obtain an in?nitely variable resistance
and at the same time connect to
of the
resistance Wire a conductor for carrying current
axial movement of the ‘same, conducting means
ing portions extending into the groove to cause
extending between the conductors mounted on
back to the apparatus. Thus, as't‘n, cylindrical
the rotatable means to conduct current from one
to: the other and wipe over the entire surfaces
the contact
will ball
rolls the
spirally down
the full
of both as the rotatable means is rotated. '
length of the Wire to change the resistance as
at the same time by bridging actiot
causes such balancing resistance point to
nested into the circuit without any contact i
being carried by the movable or rotating oar‘
Figure 3 shows a slightly modi?ed form‘ of
travelling cylindrical means
that in that in‘
stance instead of the contact ball
being held
in place by a Micarta cup screw-threaded into an
opening of the surface of the member ‘if-.4, it is
in this instance merely held in place by small
insulating disc E88 which is spring b’- sod toward
the axis of the Micarta tube by a small spring lever
I have thus provided
in?nitely adjustable
resistance which can be connected into sensit'
measuring circuit and there is no sudden step
jumps in the value of resistance as would be pro
vided in a wound resistor in which the contact
member merely slides across from one turn of the
coil to the other, but due to'the spiral drive,‘ ‘h a
travelling contact or ball
along the fl .
length. surface of the spirally wound wire as it is
driven from one end to the other} It might be
further added that ‘this construction has the
added advantage that a long Wire may be spirally
wound bet-we n relatively short end positions to
provide a further increased variation in the re
S. In resistance means, a cylindrical insulat
ing form having a spiral groove in its surface,a
pair‘ of conductors spirally wound in parallel rela
tion ‘on that section of the ‘form between the
grooves, a rotatable sleeve mounted around the
form having projections extending into the
grooves and a spring biased ball having a di
al ieter greater than the distance between the con
ductors carried by the sleeve and rolling upon the
surface of both conductors as the sleeve is ro
tated to interconnect the conductors at all times
the sleeve moves axially of the form.
1i. In resistance means, a stationary cylindrical
member formed of insulating material and having
spiral groove in its exterior surface, a pair of
spaced parallel conductors spirally Wound on the
surface of the member between the grooves, an
insulating sleeve rotatably mounted on said menu
bar hav' g internal projecting portions'extend,
into the groove to cause axial motion of the
sl eve along the ‘member as the sleeve rotates,
said sleeve having an opening in
surface in
e1 gnment with the parallel conductors enclosed.
ein, a spring
cap and ainto
ball en
gaging the spring and adapted to roll on the sur—
faces of the parallel conductors to form a con
ductive path between the two as the sleeve pro
gresses spirally along the cylindrical member.‘
I claim:
1. In resistance means, a cylindrical member
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