Note: Descriptions are shown in the official language in which they were submitted.
96~3
EXTENSION C07~D OF UNDERCARPET FLAT CAE~LE
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The invention relates to an extension cord of flat cable,
particular!y undercarpet ftat cable.
A known flat cable, particularly for undercarpet use, com-
prises a strip of insulated conductors located under a stiffly flexible
5 shield strip. The conductors are terminated with outlets by mounting
the cable ends in rigid insulating outlet supporting housings with the
strips in fixed longitudinal relation.
I t is often desirable to store predetermined lengths of flat
cable in reeled condition for use as extension cords. However, in the
10 known terminated cable the shield strip and the conductor strip are
' mounted in the outlet supporting housings in fixed longitudinal relation
with the consequential clisadvantage that, if the cable were so ter-
minated when in flat condition, subsequent reeling would cause relative
longitudinal movement between the shield strip and the conductor strip
15 arising from their different wound radii, resulting in strain or de-
struction of the termination. Alternatively, if the cable were so
terminated when in reeled condition, the relative longitudina7 ~iovement
between the shield strip and the conductor strip woulcl atso arise on
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subsequently unreeling the cable to flat condition, as the strips woold
be of different lengths, again resulting in strain or destruction of the
termination or unacceptable buckling of the cable.
It is an object of the invention to provide an extension cord of
flat cable tha~ can both be stored in reeled condition and will lie flat
when in unreeled conc:lition without loss of electrical performance.
A further object of the invention is to provide an extension
cord of flat cable in which the conductor strip and terminations remain
protected both in reeled and unreeled condi tions of the cable .
According to the invention, there is provided an extension
cord of flat cable comprising, a strip of insulated conductors located
for relative lonyitudinal sliding movement in a stiffly flexible
sleeve-form shield strip, the cable being mounted at opposite ends in
t rigid, insulating, outlet supporting housings wi th the concluctors
terminated with the outlets in the housin~s, one of the strips being
fixed at one end in one of the outlet supporting housings and the
other strip being mounted at that end for longitudinal movement
' relative to the one strip and the housing.
As a result of the accommodation of relative iongitudinal
movement between the shield strip and the conductor strip, the
extension cord according to the invention can both be stored in reeled
condition and be unreeled to flat condition without bucklin~ of the
cable or strain of the termination.
In an example of the invention, the shield strip is fixed in the
one housing and the conductors are terminated at that end to the
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supportecl outlet by flexible metal bands bowed perpendicuiarly to the
plane o-F the conductor strip to accommodate relative longitudinal
movement of the concluctor strip and the one housing.
In an alternative example of the invention, the conductor strip
5 is fixed in thç one housing and -the shield strip is mounted in the one
housing as a longitudinal sliding fit relative -to the conductor strip and
the one housing.
In a preferred construction, the sleeve-form shield strip
comprises metal and plastics strips bonded together along adjacent
10 longitudinal edges to extend above and below the conductor strip,
respectively, a further rnetal shield strip being located in the sleeve
between the plastics strip and the conductor strip. eoth strips are
fixed at their other ends in the other housing with conductors
terminated to leads of a plug outlet, the one housing receiving a
15 socket outlet facing away from the plane oF the cable.
Examples of extension cords of undercarpet flat cable
according to the invention ~ill now be described with reference to the
accompanying drawings in which:
Figure 1 is a perspective view of a first example of extension
20 cord according to the invention with part of the undercarpet flat cable
cut away;
Figure 2 is a fragmentary perspective view oF one end of the
first example of extension cord with part of one outlet supportin~
housing cut away
9 6 ~ 3
Figure 3 is a fragmentary perspective view of the other end of
the extension cord with part of the other outlet supportincJ housing
cu t away;
Figures ~ and 5 are fragmentary perspective views of one end
of a seconcl cxample oF extension corcl witll a cover of an outlet
supportin~J housing omitted for clarity, showillg the relative
longitudinal positions of the shield and conductor s~rips in reeled and
flat conditions of the cable, respectively.
As shown particularly in Figures 1 to 3, the first example of
extension cord comprises a predetermined length of undcrcarpet flat
cable 11 mounted at opposite encls in rigid insulating housings 12 ancl
13, respectively, supporting conventional socl<et and plug outlets 14
ancd 15, respectively.
The undercarpet flat cable 11 comprises a strip 16 of insulated
flat conductors 17 located in a s-tiffly flexible sleeve---form shielcl strip
18 comprising metal and plastics strips 19 and 20, respectively, bonded
together aloncJ adjacent longitudinal ed~;es to exter~d above and below
' the concluctor strip, respectively. ~ further metal shield strip 21 is
located in the sleeve 18 between the conductor strip 1 fi and the
plastics strip 20. It should be noted that, the strips 17, 21 and the
sleeve 18 are free to move longitudinally relative to each other prior to
termination of the cable.
The outlet supporting housin~s 12 and 13 are of generally
similar construction including cov~rs 23 and 24, respectively, adhered
or welcled to planar base portions 25 and 26, respectively, so that
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rebated lip portions 29 and 30 on the covers cooperate with rebated lip
portions 31 ancl 32 on the respective bases to define cable receiving
moutlls 33 and 34.
As shown more particularly in Figure 3, one end of the
5 undercarpet flat cable 11 is mounted in the housing 13 by rivets or
other fasteners 36 such as projections with heat deforrned heads
integral with the base portion 26 and which pass through both shield
strips 19 and 21 and the insulation of the conductor strip 16 at
locations between the conductors 17, fixing the cable strips relative to
10 each other and to the housing base 26~ The inclividual conductors 17
are crimped to respective live and neutral leads of the socket outlet 15
by conventional terminals 37 having insulation-piercing arms which are
curled back under the conductor strip into electrical engagement with
the conductors. A tab terminal 38 held by a rnetal rivet passing
.
15 through top and bottorn shield strips 36 is connected by leads to the
ground conductor of the cable 11 and socket outlet 15. A bush 3~
secures the leads of the plug outlet 15 extending through an aperture
' in the top of the cover 24.
As shown more particularly in Figure 2, the other end o-f the
20 undercarpet flat cable 11 is mounted in the duplex socket supporting
housing 12 by rivets Ll1 or other fasteners which pass through
insulation 16 o~ the exposed conductor strip between the individual
~onductors 17 thereby fixing the strip to the housing base 25, whilst
the sleeve-form shield strip 18 is received as a longitudinal sliding fit
25 in the mouth 33. The individual conductors 17 are also terminated by
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crimpiny to conventional terminals connected to leads extendincJ to
terminals of the conventional duplex socket outlet 14.
~ Aovement of the cable frorr the flat condition shown to a
wouncl or reeled condi-tion, indicated by broken lines, will cause the
5 sleeve-form shield s-trip 18 to slide longitudinally further into the
housincJ to the position shown in broken lines. As the conductor strip
16 is fixed, no stress is imposed on the terminations whilst such
sliding movement will permit the cable to lie flat when unwound or
unreeled . L ongitudinal rnovement of the shield strip 21 will also be
10 accommodated.
In a seconcl example of the invention, shown particularly in
Figures 4 and 5, the cable 11 is terminated at one end as shown in
Figure 3 and the sleeve-form shield strip 18 is fixed at the other end
to the base 31 by rivets 46 or other fasteners. Flexible metal bands
15 L17 which bow perpendicuiar ly to the plane of the concluctor strip 16
are clamped at one of their ends to respective flat conductors 17 by
conventional terminals 48 which embrace the strip ends and are
crimped around the conductors in a similar fashion to terminal 37 the
other ends of the bands being crimped to respective socket outlet
20 leads by conventional terminals 37 also crimped to an insulating
termination strip 49.
Movement of the cable from the wound or reeled condition of
Figure 4 to the flat condition of Figure 5 will cause the conductor
strip 16 to slide longitudinally into tl-e housing from the position
25 shown in Figure 4 to the position shown in Figure 5, such movement
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being accommodated by increased bowing of the bands 47 without
undue strain being imposed on the terminations. Unbowing of the
bands 47 will also permit the cable to be lie flat when unwound or
unreelecl .
It should be noted that any tendency for relative movement
between the metal shield strip 19 and the plastics strip 20 when
changing the cable between wound and unwound conditions will be
accommodated by longitudinal flexure of the plastics strip without
causing buckling of the cable.
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