INVENTION TITLE ELECTRIC FENCE DROPPER

This invention relates to a new device which makes possible an improved method of installing electric fences especially for deterring birds from places where the birds are unwelcome.

BACKGROUND Electric fence technology has been in use for at least 75 years, mainly for the control of livestock in rural industries.

The components of an electric fence typically include posts, wires, an energizer and an earth-return system. The energizer, attached to an electric power source, emits a high voltage electrical pulse approximately every second along the live wires of the fence. A leading manufacturer describes the action of the fence as follows:

"An animal touching this live wire creates a path for the electrical current through its body to the ground and back to the energizer via the earth (ground system), thus completing the circuit. The greater the shock the animal receives the more lasting the memory will be and the more the fence will be avoided in the future" (Gallagher).

The present invention relates to three additional facts about electric fencing:

1. It is not always possible for the current to return to the energizer via the ground:

(a) the ground may be a poor conductor due to the composition of the soil and lack of moisture.

(b) the creatures intended to be shocked by the fence may not be standing on the ground, e.g. birds.

In these situations it is necessary to complete the circuit directly by wire, i.e. the animal must touch the live wire and the earth-return wire simultaneously to complete a circuit.

2. A fencing component not mentioned above is the DROPPER (or spacer) which may be described as a light-weight batten attached to the horizontal wires of a fence to maintain the spacings of the wires in the intervals between posts. Posts and droppers serve a similar function in respect of the spacing of the wires, but a post is supported by

its lower part being buried in the ground whereas a dropper is suspended by the wires themselves and is not buried in the ground.

3. A dropper designed to control the distance between two wires (live and earth) such that a bird may perch on both at once, is a very small dropper the characteristics of which are the subject of this present invention.

Previously published methods of using electric fence technology for the control of birds have depended on:

(a) Posts at frequent intervals to ensure that the wires do not touch or tangle thus causing short circuits. OR (b) The wires (live and earth) being embedded in an insulating material which supports and separates the wires along their entire length. The wires are thus only partially exposed; the birds cannot grasp the wires but only stand on them; the manufacturing process is expensive to the extent that general use in horticulture is not feasible; there are manufacturing difficulties in achieving a product that does not twist and create general handling problems.

In contrast to (a) and (b) above, a bird fence constructed with use of the self-contained electric fence droppers of this invention can have posts at greater intervals e.g. 20 or 30 metres apart; most of the wire is fully exposed thus enabling birds to properly grasp the two wires; the electric- fence method of deterring birds in broad-acre horticulture has become, for the first time, practicable because of the cheapness and ease of construction.

Damage caused by birds is valued annually at hundreds of millions of dollars in many countries, especially to fruit crops and also in many other situations. Electric fence research and development has been proceeding for 75 years without producing, until this present invention, a satisfactory method of installing electric fence wires for birds to perch on.

DESCRIPTION

These problems and deficiencies are overcome by the present invention, which is a self- contained non-conductive electric fence dropper containing a cavity for each wire, the access to each cavity being a funnel-shaped space for location of the wire in preparation for the wire being clicked into the cavity. A secure grip on the wires is a product of three

features of the dropper: the accuracy of fit of the cavity in respect of the diameter of the wire; the length of wire enclosed by the dropper; and the resilience of the dropper in resuming the shape of the cavity after the wire has been clicked into place. The resilience of the dropper cavity is a product of the type of material and the design of the dropper (specifically the thickness and shape of the material that defines the cavity) resulting in the efficient combination of strength and flexibility. The method of manufacturing the self-contained electric fence dropper is likely to be plastic injection moulding or whatever similar technology may be found to suit the purpose.

In one form of the invention the number of cavities in the dropper is two, with the distance between wires, by way of example only, being 13mm centre to centre, which allows many species of birds to grasp the two wires simultaneously when they perch on them.

In other forms of the invention it would be possible to vary the number of wires and the spacing between the wires. An example would be a dropper with three cavities for wires spaced say 20 mm apart, being LIVE - EARTH - LIVE or EARTH - LIVE - EARTH. An application for this form of the dropper, and any other form including the two-wire form described above, would be in a fence to control animals which are covered with insulated hair and walking on dry, non-conductive ground. The wires being close together enables the animal to complete a circuit with a sensitive part of its body such as its mouth or ear.

The need for the droppers, in fences with very close wires, to be self-contained relates to the problem inherent in other forms of droppers in which metal devices used to attach the wires to the droppers would result in short-circuiting between the wires.

To assist with understanding the invention, reference will now be made to the accompanying drawings which show one example of the invention.

In the drawings:

FIG. 1 shows one example of a self-contained non-conductive electric fence dropper according to this invention.

FIG. 2 shows the application of such a self-contained non-conductive electric fence dropper where the objective is to provide an electric shock to birds in proximity to fruit trees.

Referring to FIG. 1 it can be seen that the self-contained electric fence dropper according to this invention contains two cavities 1 and 2 which grasp the wires 3 and 4. Openings 5 and 6 to the cavities 1 and 2 are funnel shaped to facilitate location of the wires 3 and 4 in preparation for finally clicking the wires into place.

The body 7 of the dropper should be of such shape and thickness of material as provides the necessary strength to survive the stress incurred during installation and subsequent movement of the wires due to wind and contact with birds and animals.

The length 8 of wire within the cavity of the dropper should be sufficient, together with the precise fit of the cavity and the resilience of the material defining the cavity, to maximize the grip on the wire and minimize twisting of the wires after installation.

By way of example only, the wires 3 and 4 could be 2.5mm diameter galvanized steel which is commonly available fencing wire. The distance between the wires for deterring many species of birds could be 13mm, which is close enough for the birds to perch on and complete a circuit but sufficiently far apart to avoid unintended short circuiting between the wires.

FIG, 2 shows in diagrammatic form how the self-contained electric fence dropper 20 is used in the field. An energizer 21 plugged into a power source 22 has a LIVE 23 and an EARTH 24 wire leading to a garden or orchard 25. The wires are placed in a position where it is believed, from observation, the birds would be inclined to perch before attacking the fruit 26.

The two wires 23 and 24 are attached to posts, 27 and 28, the LIVE wire 23 being insulated at the posts, the EARTH wire 24 not necessarily insulated.

The distance 29 between posts may be, for example, 30 metres. The end posts 27 need to be thoroughly supported to allow the wires to be strained reasonably tightly. Intermediate

posts 28 have the function only of supporting or guiding the wires and may be of light material and do not need to be put deeply in the ground.

The. self-contained electric fence droppers 2Δ of this invention, ate snapped, or clicked onto the wires about every 1 metre or at smaller or greater intervals depending on how straight and tight the wires are. The purpose of the droppers 20 is to maintain the spacing between the wires.

As can be seen from this description there are no metal attachments to compromise the insulation between the two wires when they are held by the self-contained non-conductive electric fence dropper of this invention. Also no tools are required for installation; the pressure of fingers and thumbs is sufficient.

The above-mentioned features of the electric fence dropper of this invention now make the large scale application of electric fence technology to the deterring of birds, especially in rural industries, both practicable and economical for the first time.