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Патент USA US2111220

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March 15, 1938.
Filed July 18,1956
5mm? T M1012
"K G .
Patented Mar. ‘15, 1938
' 2,111,220.
George. E.’ Megow, South Milwaukee,
signor to Allen-Bradley Company, Milwaukee,
Wis., a corporation of Wisconsin
Application July 18, 1936, Serial No. 91,305
1 Claimf (01;. coll-cs)
This invention relates to electrical resistor of the invention constructed according to the
units and refers particularly to ?xed resistor best modes so far devised for the practical ap
units used in radio circuits and especially radio plication of the principles thereof, and in which:
Figures 1 to '7, inclusive, are ‘perspective views
Fixed resistors oi this type now generally of resistor units illustrating several different em
consist of a molded or lumped body of resistance
material with wire leads projecting from the
ends thereof by which the unit is connected in
the circuit.
Modern radio receivers and particularly those
for use in automobiles. have their composite ele“
ments compacted into small space and the trend
is to even greater compactness. Obviously,
crowding the parts together in this manner en
15 tails special provision for electrical insulation
as the clearances between the different parts is
ordinarily inadequate.
In keeping with this growing necessity for
positive electrical insulation, it is an object of this
invention to provide a simple eilicient manner
of insulating ?xed resistor units of the char
acter described.
Resistor units of this type are color coded to
indicate their different values and generally the
color code marking is applied directly to the body
of the. unit. This marking should be visible at
all times and consequently, it is another object of
this invention to provide an insulation for re
sistor units of the character described which is
30 transparent so as not to conceal the color code
bodiments of this invention;
Figure 8 is a cross section view through Figure
l, on the plane of the line 8-8; and
Figure 9 is a cross section view through Figure
‘l, on the plane of the line 9-4.
Referring now particularly to the accompany
ing drawing, the numeral 5 designates the body
of a lumped resistor unit which is preferably cy
linclrical with an outer cylindrical wall 6 and
end walls l. Projecting from the ends of the
body are who leads 8 by which the unit is con
nected in an electrical circuit.
To indicate the resistance value of ‘the unit
and possibly also its plus or minus tolerance,
bands 9 of di?erent color combinations are ap
plied directly to the cylindrical Wall S of the
To attain the objects of thisinvention by pro~
viding an insulating covering which Will be trans
parent so as not to conceal the color code mark
ing and at the same time afford adequate elec
trical insulation and a degree of protection
against moisture, the body of the unit and pre1f~
erably a substantial portion of its leads 8 are
encased in a shell or casing ill of transparent 30
material having the desired characteristics. This
A further object of this invention is to pro
vide means for insulating resistor units which
affords a degree of protection against moisture
shell or casing it may be applied in. any of a
number of different ways and in Figure 1 the
shell is in the form of a tube slipped over the
and which adds to the mechanical strength of the
resistor unit with its end portions extending out
unit and provides protection against obliteration
of the color code marking.
While adequate-insulation and transparency
to closely engage the leads and thereby hold it
are of primary importance, low cost is also an
important consideration, and consequently it is
another object of this invention to provide an in
sulatlng enclosure for lumped resistor which is
made of inexpensive material easily formed and
over the Wire leads and twisted as at it so as
self onto the unit.
The shell or casing may be composed of any~
one of a number of different substances, prefer 40
ably some transparent organic ?lm such as “Cel
lophane", “Pliofllm”, a cellulose acetate and mod
i?ed' forms thereof, a. cellulose nitrate and modi
?ed forms thereof, or any other synthetic resin
With the above and other objects in view
which will appear as the description proceeds,
this invention resides in the novel construction,
product, and “Plio?lm” is a chlorinated rubber
combination and arrangement of parts substan
“Cellophane” as is well known is a cellulose
tially as hereinafter described and more particu
The casing or shell may ?t the body of the re
larly de?ned by the appended claim, it being
sistor snugly or loosely as shown in Figures 1 r
understood that such changes in the precise em
bodiment of the hereindisclosed invention may
be made as come within the scope of the claim.
and 8.
_'I'he accompanying drawing illustrates seven
5 complete examples of the physical embodiment
With certain types of material, especially . -
“Cellophane”, a loose fit is preferable as this
material unless specially treated will he electri
cally conductive after being subjected to humid
ity, if it is fitted’ closely to the unit, whereas, if a
?tted loosely, it is free from this defect. “Plio
?lm” on the other hand will not conduct elec
trically whether it is ?tted to the unit tightly or
Obviously, the casing or shell may be formed
in many different ways. In Figure 2, it is built
up by winding a ribbon l2 of the desired trans
parent material continuously and progressively
over the wire leads and the body 0!’ the unit as
10 shown.
If desired, only the body of the unit is cov
ered with the insulating shell, and in Figures 3,
4, and 5, different ways in which this may be
done are shown.
In Figure 3, an insulating and protecting shell
is formed by winding a ribbon of the desired
material onto the unit.
In Figure 4, a tube l3 slightly longer than the
length of the unit is closely fitted to the body.
20 Where this method is employed, it is preferable
to use a substance other than “Cellophane” as it
entails a tight close ?t.
In Figure 5, a sleeve l4 closely ?tted to the
body as in Figure 4 has its end portions crimped
25 or pressed down against the end walls ‘I of the
body as at I5 to add to the protection a?orded by
the covering.
- The advantages of the invention are also ca
pable of realization by merely slipping a tube i6
30 of suitable transparent insulating material over
the unit with its end portions projecting out over
the wire leads without speci?c provision for
holding the same in place.
In theembodiment of the invention shown in
Figure 7, protection against moisture is particu
larly obtained. In this modi?cation, the pro
tecting shell consists of two telescoped sleeves l1
and I8 pushed onto the unit from opposite ends
thereof and with their adjacent open ends over
lapping as at IS. The outer ends of the sleeves
are reduced in diameter and have end portions 2'
,to closely hug the wire leads and thereby insure
the greatest protection against the entrance of
Inasmuch as the end portions 20 frictionally
engage the wire leads, no other means need be
provided to hold the enclosing shell on the unit
and the sleeves need not ?t the body closely. 10
However, if desired, the overlapping ends of the
sleeves may be fused together or a juncture may
be formed therebetween by merely bringing the
inner ends of the sleeves into abutting relation
and then forming a fused juncture therebetween.
From the foregoing description taken in con
nection with the accompanying drawing, it will
be readily apparent to those skilled in this art
that this invention in all of its various modi?ca
tions provides a simple and e?lcient manner. of 20
electrically insulating ?xed resistor units, and
that in each instance, the desired insulation is
obtained without concealing the color code mark
ing of the unit and without in anywise com
plicating the design or construction 01' the unit
and at a minimum cost.
What I claim as my invention is:
An insulated electrical resistor comprising: a
lumped resistor body; wire leads projecting from
opposite ends thereof; and an insulating cover 30
ing for the body and its leads, said covering being
composed of a thin transparent cellulose mate
rial and fitting the body loosely so as to provide
an air space between the body and the covering,
and the ends of the covering being ?tted closely
to the Wire leads.
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