Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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m e present invention refers to fencing. It is
often necessary to fence-off one region from another to mark
the boundaries of private property or to enclose certain
areas. Special fences have been designed for various purposes
ranging from decorative fences and boardings to barbed wire
fences for livestock and military purposes.
Various endeavours have been made to design a fence
suitable for different purposes. While domestic animals fear
a barbed wire fence, man is extremely careful to ensure that a
fence surrounding a garden should not hurt a child. Fences
around dwelling houses are usually made to look decorative but
a fence for livestock often turns out to be an eyesore. A fence
around a grazing ground should be easily movable while a more
permanent fence might be more appropriate for other purposes.
It has, surprisingly enough, been proved that an area can, to
a great extent, be enclosed by one type of fence which serves
the purposes provided by particular types of fences avallable
for different purposes. The present invention relates to a
movable fence capable of marking the boundaries of an area
without causing harm to man or livestock.
To deter wild or tame animals from touching a fence
it may be practical to make the fence of plastics ribbons
having electric conductors to which is fed a high voltage,
the ribbon being secured between poles by means of plastics
rings. On touching the ribbon the animal receives an electric
shock when a charge passes from the ribbon to earth. Several
fences of this type have been tested and certain weaknesses
discovered. m e wind tends to make the ribbon move which is
quite an advantage because this means that the fence can be
seen more easily but this may cause fatigue in the ribbon and
fixtures resulting in them eventually breaking.
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The durability of the ribbon is not increased by
making the ribbon wider since this increases the effect of the
wind. Better structural qualities have, therefore, had to be
based on the thickness of the ribbon. Satisfactory results
have only been achieved through the use of a laminated three-
layer ribbon, i.e., a metal foil with a plastics layer on both
sides. The risk of ribbon failure is highest at the poles
where the fixtures used caused a sharp bend in the ribbon.
- Not only the wind, but also light affects plastics
materials, especially ultra-violet light, and only a very
limited number of plastics materials possess the necessary
qualities of resistance.
The primary objective of the present invention has
been to improve the form of fixing the ribbon to the poles so
as to reduce the risk of ribbon failure at this point.
In accordance with this invention, therefore, we
provide fencing comprising a loop of ribbon pulled through an
elastic tube to form an eye and secured to a pole by the eye
enclosing the pole, the elastic tube being compressible longi-
tudinally by tensioning the ribbon each side of the eye. Asthe ribbon stretches, the eye is pulled around the pole
compressing the tube to provide a smooth connection. It has
proved, surprisingly enough, that a ring of plastics foil,
where the foil is even thinner than 50 ~m, (micrometers or
10 3 millimeters of 10 6 meters) is sufficient, while the
previous fixtures of a thickness of 0.2 mm not only damaged
the ribbon but even broke. With this we have achieved improved
stability of the fixture along with cutting construction costs.
In accordance with a further broad aspect of the
present invention, there is provided a fence comprising a
plurality of poles and at least a ribbon extending between the
poles. The improvement in the fence construction is that a
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portion of the ribbon corresponding to each pole is looped
about the pole and an elastic tube necks each loop of the
ribbon. The ribbon is held on the pole by tension in the
ribbon and consequently on the tube.
Fencing in accordance with this invention also
aims to protect the ribbon against various other effects. For
example, the ribbon is protected by a coloured plastics coating
which does not pass but absorbs ultra-violet light or by a
coating of metal foil or metal powder to reflect light. The
metal layer which may be aluminium, will reflect light and
provide a twinkling effect which will call attention to the
existence of the fence and clearly mark the area enclosed by the
fence. If the opposite side of the ribbon is supplied with a
coloured surface to hinder the passage of the ultra-violet light,
then this will offer a sharp contrast to, e.g., glistening snow,
which again means that the fence is more clearly visible even in
winter and when fields are covered with snow. This is of vital
importance when the fence is to be used for game-keeping
purposes.
The above form of metal coated ribbon offers a
considerable advantage for, if the outer conductor breaks,
sparks will jump from the edge of the inner ribbon to that of
the outer one. The joint will have a satisfactory effect if
the outer metal surfaces of two ribbons to be joined are put
together surface-to-surface. Should a breakage of the joint
occur, then the charge will pass from the inner metal layer via
the outer conductor.
In fatigue tests improved results have been obtained
when reducing the thickness of the metal or aluminium foil from
30 ~um to 15 ~um. It is possible to work with aluminium foil as
thin as 9 um. There is, however, a minimum limit below which
certain minor damage may cause burning due to the high voltage
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applied to the foil. This may happen when using a layer of
atomized metal powder rather than foil.
The following description should be read in
conjunction with the attached drawing, in which:
Figure 1 shows a fence in accordance with the
present invention; and
Figure 2 shows a device for fixing a ribbon on a
pole for the fence shown in Figure 1.
References 1, 2, 3 and 4 show poles which may be of
plastics or any other suitable material and with any chosen
cross-section. An appropriate cross-section should be
circular and the material a plastics material. Between the
poles is a plane ribbon 5 which has, as its base, a metal ribbon,
e.g. aluminium, which is plastic-coated on both sides. The
plastic coating can either be sprayed on or fitted on, whichever
is more convenient. On one plastic coated side of the ribbon is
a reflective metal layer while the other side has a layer which
will prevent damage from ultra-violet light. The ribbon is
twisted, as shown in the drawing and fixed to each pole by
pulling a loop of ribbon through an elastic ring 6 as shown in
Figure 2. The loop is fitted over the pole and the diameter of
the loop is reduced by pulling the ring to the left so that the
ribbon stays on the pole. The ring is designed as a tube of,
e.g. plastics material, having a thickness of 50 ym. Since the
tube is elastic it can extend or compress and thereby reduce
chaffing of the ribbon on the pole. Other types of ribbon, cord,
wire or the like elongate flexible members may be used with the
rings so as to make use of the flexibility of these fixtures.
EXAMPLE 1
A ribbon of a width of 10 mm comprising the following
layers of foils glued together,
15 ~m aluminium, 190 ~m polyester, 15 ,um aluminium,
,f"'--
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190 ym polyester, and 30 ym black polyethene. The ribbon is
fitted on tubular poles by means of rings of 100 ~m thickness
made in the form of a laminate of nylon and polythene. High
voltage electric impulses of two thousand volts are fed to the
metal layer. This electric fence has the same effect as wild
game mirrors which reflect light.
EXAMPLE 2
A ribbon of 12 mm made of glass fibre reinforced
polyester of 350 ym thickness with a coating on one side of
20 um aluminium foil and on the other side, of 100 ,um red nylon.
The poles are made of glass fibre reinforced polyester.
Using three mutually parallel ribbons, fitted on the poles,
this simple and decorative fence may be used to fence-in a
lay-by or meadow.
EXAMPLE 3
In order to reduce the effects of the wind without
having to alter the reinforcing of the plastic, an 8 mm ribbon
has been tested, consisting of an inner layer of 15 ~um aluminium
covered on both sides by 100 ~m polyester and, on the outer
side, of 15 ,um aluminium foil, by both sides being coloured.
Poles and fixtures are the same as in Example 1.
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