WO2009039858A1

WO2009039858A1 - An electrical slug barrier, a kit and a method

Info

Publication number: WO2009039858A1
Application number: PCT/DK2008/050235
Authority: WO
Inventors: Ole Tidemann
Original assignee: Slugvision V/Ole Tidemann
Priority date: 2007-09-28
Filing date: 2008-09-26
Publication date: 2009-04-02
Also published as: DK200701406A; DK177074B1

Abstract

An electrical slug barrier (1) comprising a set of elongate electrically conductive zones (10, 11, 12, 13) arranged substantially in parallel; at least one electrically insulating zone (20, 21, 22, 23), formed between said electrically conductive zones (10, 11, 12, 13); said electrically conductive zones (10, 11, 12, 13) being connectable to a source of electrical energy in order to provide a voltage between each of said electrically conductive zones (10, 11, 12, 13), wherein said electrically conductive zones (10, 11, 12, 13) are arranged on, and along a longitudinal axis, A, of an elongate member (30) flexibly bendable in at least one first plane parallel to said longitudinal axis, A, and in another plane perpendicular to said first plane and parallel to said longitudinal axis A.

Description

An electrical slug barrier, a kit and a method

Field of the invention

The invention concerns an electrical slug barrier. More specifically the invention concerns an electrical slug barrier of the kind having a set of substantially parallelly arranged elongate electrically conductive zones separated by electrically insulating zones provided between said electrically conductive zones.

Background of the invention

Slug barriers, snail and slug fences based upon the basic principle that an electrical voltage applied between electrical conductors will cause discomfort for snails and slugs when attempting to pass the conductors, are known in the art. The applied voltage is not supposed to kill the snails or slugs, but the discomfort is extensive enough to make the intruding slugs give up the intrusion. German patent No. DE 102 005 041 713, U.S. Pat No. US 4706941 and German patent No. DE 3 930 013 applies this principle. However, a number of severe drawbacks are inherently related to the barriers disclosed in the mentioned documents. The drawbacks will be described in the following paragraphs.

German patent, DE 102 005 041 713, describes a snail fence consisting of 2 electrical conductors mounted to a planar grid formed in plastic, which is vertically fastened to shafts. Due to the said shafts, however, the said fence cannot be mounted in areas with flagstones, asphalt or similar hard surfaces. Furthermore, additional tools must be needed for mounting in areas with stones in the ground and also the fence is difficult to move. Also, the fence is sensitive to strong wind, strokes, kicks, or similar mechanical forces caused by animals or human beings. Such forces applied to the fence will cause the fence to loosen, break or get damaged in some other way, whereby the protection against slugs will be considerably reduced or eliminated. Furthermore this fence will require a high degree of accuracy when mounting to ensure that snails or slugs cannot pass underneath the fence. The fence is therefore only suitable for usage on completely flat surfaces, as holes in the ground, small stones, roots, and other irregularities will allow for snails and slugs to cross under the fence. The disclosed fence is also very sensitive to short circuits, as one single short circuit along the fence will remove the protective effect. Also disclosed is a requirement for the use of alternating voltage, which seems unnecessary, inadequate and speculative. Finally, the described fence is difficult and expensive to manufacture, as the fence consists of different parts needing manual assembly, or a complicated, and expensive automated process at best. Further, excrements from snails, mucus, dead snails, dead plants, plant growth, weeds and other kinds of contamination will reduce the protective characteristics of the fence due to the conductivity properties of the disclosed material. Also the disclosed fence is difficult to clean, especially if cleaning requires that the fence is moved, which is difficult due to the shafts.

U.S. Patent, US 7 706 941, discloses an electrical snail fence like DE 102 005 041 713, consisting of three elements, namely, (a) two or more electrically conductive surfaces, (b) an electrical power connection part, and, (c) a mechanical mounting mechanism to which the conductive surfaces are mounted. This fence, however, is difficult and expensive to manufacture, as the conductive surfaces need to be attached to a mechanical arrangement with sufficient strength and stiffness and with an appropriate distance between the conductive surfaces. The fact that the conductive surfaces according to the primary claim constitute a separate entity must cause high production costs and technical production challenges. The implementations described in the said U.S. patent are based upon shafts usage for mounting in the ground in a similar way as for the mentioned German patent No. DE 102 005 041 713. The disclosed fence therefore suffers from basically the same drawbacks and limitations as the German patent.

German patent, DE 3 930 013, describes a snail fence consisting of two electrical wires embedded in a semi conductive material in a planar structure. The intension is to provide a snail fence, which is easy to lay out in a garden and at the same time does not suffer from short circuit risks. However, the disclosed plastic band profile fence suffers from similar deficiencies as those fences previously described. In practice it is not simple to lay out. Due to the band profile the fence may only be laid out in straight tracks because the band profile cannot be turned without substantial deformation. Therefore it will not be possible to bound an area with one separate band profile fence. Bounding a rectangular area will require use of 4 separate fences that either have to be power supplied separately or need to be connected together by special, separate mechanisms. In any case such bounding of a rectangular area will be impractical, expensive and probably reduce the efficiency of the fence around the connection places. Bounding circular areas, for instance around a flowerbed will be even more difficult or impossible unless the plastic band profile is heeled over around the bed. Such heeling though is not a stable condition and is probably difficult to achieve in practice, and would render the disclosed fence a duplicate of the two other fences described above. Moreover the fence is relatively stiff due to the band profile, a stiffness that will probably increase due to the fact that two wires are attached to the profile and the fact that the profile in preferred embodiments contains ribs. All together the stiffness must be so pronounced that the slug fence in practice will be difficult to adapt to irregularities of the ground where the fence is supposed to be used. Gabs between the ground and the fence are therefore to be expected. Due to the fact that the fence has no conductors underneath, hence it will provide no intrusion protection where gabs are present, and even if the gabs are minor as the snails or slugs may find their way through as there is no risk of electrical discomfort underneath the band profile. This problem, however, may to some extent be avoided if the band profile as suggested in the description is secured to the ground. That will on the other hand make lay out, cleaning, and moving about the fence more difficult. Also removal of growth and weed will be more difficult. Fastening of the fence to a ground with a surface consisting of asphalt or flagstone or other harder surfaces is also assumed difficult. The described short circuit characteristic is subject to discussion. It is true that the described encapsulation of the two metallic conductors in a semi conductive material ensures that no major voltage drop will take place apart from in the area close to the short circuit. The question is, however, if this characteristic actually solves a true potential short circuit problem. In case of a short circuit local passage of snails will presumably be allowed close the short circuit. Even if a part of the fence is still assumed to be active in case of one or more local short circuits there is no protection against the local effect of a local short circuit. In fact the fence will be more sensitive to the effect of local low resistance impedance that it would have been if metallic conductors had been used. The reason for this is that the local internal resistance of the system is higher than it would have been without the encapsulation and hence the voltage drop will be larger. Moreover the fact that the said patent uses only two conductors - as opposed to more conductor pairs - is in itself a reason for that low impedance loads will reduce or eliminate the described protection effect, as there is only one single protection zone. Finally, the disclosed snail fence has got the problem that mucus from the snails, excrement's, rain water, earth particles and other kinds of remainders will gather in the ribs, whereby the risk of electrical grounding or short circuiting is increased in the entire length of the fence.

Hence an improved slug barrier, and in particular a more efficient and or reliable slug barrier would be advantageous.

Object of the invention

An object of the invention is to provide a slug barrier, which is very easy and fast to lay out and to move about without loss of functionality despite larger or smaller irregularities in the ground surface on which the barrier is to be used. More particularly it is an object to provide a slug barrier that is very easy to lead around earth clods, stones, bushes, trees, and other obstacles and irregularities. Furthermore it is an object to provide a slug barrier that shows very little sensitivity against any direct or indirect influence by slugs, snails, other animals or insects, weather conditions, or any thing else. Furthermore, it is an object to provide a slug barrier that that is very easy and cost efficient to produce. Yet further, it is an object to provide a slug barrier that is very easy to clean in order to maintain constant protection against snails. Yet further, it is an object to provide a slug barrier that is very easy to remove and to stow away and store, e.g. outside the season. It is a further object of the present invention to provide an alternative to the prior art.

Summary of the invention Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing an electrical slug barrier comprising a set of elongate electrically conductive zones arranged substantially in parallel; at least one electrically insulating zone, formed between said electrically conductive zones; said electrically conductive zones being connectable to a source of electrical energy in order to provide a voltage between each of said electrically conductive zones, wherein said electrically conductive zones are arranged on, and along a longitudinal axis of an elongate member flexibly bendable in at least one first plane parallel to said longitudinal axis and in another plane perpendicular to said first plane and parallel to said longitudinal axis.

The invention is particularly, but not exclusively, advantageous for obtaining an electrical slug barrier that efficiently follows ground contours whereby unintended unprotected passages in the barrier may be avoided.

Embodiments of the invention are described in dependent claims 2-15.

In a second aspect of the invention the above described object and several other objects are intended to be obtained an electrical slug barrier comprising a set of substantially parallelly arranged elongate electrically conductive zones; at least one electrically insulating zone, formed between said electrically conductive zones; said electrically conductive zones being connectable to a source of electrical energy in order to provide a voltage between each of said electrically conductive zones, wherein said electrically conductive zones are arranged on, and along a longitudinal axis of an elongate member, the elongate member being of oval or circular cross sectional shape.

Embodiments of this second aspect of the invention are described in dependent claims 5- 15.

The above described object and several other objects are also intended to be obtained in a third aspect of the invention by providing a kit comprising an electrical barrier according to any of the embodiments of the first and second aspect described above and a processing unit connectable to said elongate electrical conductors, said processing unit comprising means for measuring the voltage between the elongate electrical conductors, and/or the power consumption of the elongate electrical conductors. Embodiments of this third aspect of the invention are described in dependent claims 17- 18.

The above described object and several other objects are also intended to be obtained in a fourth aspect of the invention by providing a method of preventing slug passage, the method comprising the steps of providing an electrical slug barrier according to any one of claims 1-16, - applying to said electrical slug barrier a voltage of 1-35 V.

Embodiments of this fourth aspect of the invention are described in dependent claims 20- 22.

Throughout this document the term "substantially in parallel" with respect to the arrangement of the conductive zones should be construed as "following an adjacent path without crossing or touching each other". The width or distance between the conductive zones is preferably uniform. However, due to production inaccuracies etc an exactly constant distance may not be realized in practice.

Throughout this document the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality.

Brief description of the drawings

The snail barrier according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

Fig. IA shows a slug barrier according to an embodiment of the invention; - Fig. IB shows a cross section through the slug barrier shown in Fig. IA;

Fig. 2 shows the slug barrier of Figs. 1 A and IB hooked up to a source of electrical energy;

Fig. 3 shows a test setting for snail barriers;

Fig. 4 shows a slug barrier according to an embodiment of the invention; - Fig. 5 show examples of cross sectional shapes of an elongate member of a various embodiments of a slug barrier;

Figs 6 is a photo showing snails on a test setting as in Fig 3, before crossing of conductive cupper strips; Fig. 7 is a photo showing snails on a test setting as in Fig 3, during crossing of conductive cupper strips;

Fig 8 is a photo showing measurement of the conductive properties of snail mucus; and - Fig 9 is a photo showing a test version of a snail barrier according to the invention.

Embodiments of the invention

Referring firstly to Fig. 4 showing a principle outline of an embodiment of slug barrier 1 the invention, the slug barrier 1 comprises an elongate member 30 and a set of electrically conductive zones 10, 11, formed on the elongate member 30, having an longitudinal axis A.

The electrically conductive zones 10, 11, 12, 13 (see also Figs. 1 and 2) are preferably formed as a set of substantially parallelly elongate electrically conductive zones along longitudinal axis A of the elongate member 30. Between each pair of electrically conductive zones 10, 11, 12, 13 is formed an electrically insulating zone 20, 21, 22, 24.

The electrically conductive zones 10, 11, 12, 13 have means, making them connectable to a source of electrical energy in order to provide a voltage between each of said electrically conductive zones 10, 11, 12, 13, as shown in Fig. 2.

The elongate member 30 is flexibly bendable in at least one first plane, Pl, parallel to said longitudinal axis, A, and in another plane, P2, perpendicular to said first plane and parallel to longitudinal axis A. in order to ensure this the elongate member 30 of the electrical slug barrier preferably has a maximum width, Wl, perpendicular to said elongate axis A and a minimum width, W2, perpendicular to said elongate axis A, the ratio between the maximum width and the minimum width being in the range ¹Z--I.

In the case shown in Fig. 1, where the elongate member 30 is a tubular structure, such as a hose, with a circular cross section (perpendicular to the elongate axis A), the barrier 1 is flexibly bendable in all directions.

In embodiments of the invention, and as shown in Figs 5A-E the elongate member 30 may have different cross sectional profiles of shapes. In preferred embodiments the elongate member 30 has an oval cross sectional shape, as seen in Fig. 5B or a circular cross sectional shape, as seen in Fig. 5A. However other, cross sectional shapes may be conceived. In preferred embodiments the elongate member 30 is a closed tubular structure, e.g. cylindrical. However, in other embodiments, e.g. as shown in Fig. 5C the elongate member may be an open structure, e.g. as an sliced up hose.

The elongate member 30 is preferably a hollow structure such as a hose. However, in some embodiments (not shown) the elongate member may be solid.

In an embodiment and as shown in Fig 1 the flexible elongate member 30 of the electrical barrier 1 is provided with exactly two substantially parallelly arranged elongate electrically conductive zones 10, 11. In one further embodiment hereof, the two substantially parallelly arranged elongate electrically conductive zones 10, 11 are arranged within an arc of 90° around a perimeter of the flexible elongate member 30.

In other embodiments three or more substantially parallelly arranged elongate electrically conductive zones 10, 11, 12, 13 are arranged on and along the elongate member 30.

Thus, in preferred embodiments the elongate electrically conductive zones 10, 11, 12, 13 are distributed around the entire perimeter of the elongate hollow member 30.

In other embodiments (not shown) the electrical barrier 1 according may comprise elongate electrical conductive zones 10, 11, 12, 13 spiralling along the elongate hollow member 30, however preferably still substantially parallel.

In preferred embodiments the distance or width between the elongate electrical conductive zones 10, 11, 12, 13 is less than 1 cm, i.e. the width of the isolating zones 20, 21, 22, 23, 23 is less than 1 cm.

In one embodiment the elongate member 30 may be formed in rubber.

In an embodiment (not shown) the elongate member 30 may be a hollow tubular structure comprising regularly spaced apertures, and be equipped with means for connection to a pressurised water supply. Thereby, the barrier may serve the dual purpose of slug barrier and irrigation.

This invention provides a simple, efficient and cost effective electrical snail and slug barrier 1 e.g. in an embodiment as shown in Fig.l by means of a flexible hose equipped with a number of parallel, electrically conductive tracks or zones 10, 11, 12, 13 distributed along and around the circumference of the hose. A voltage is applicable to the conductive tracks in pairs whereby a number of barriers are created against passage of slugs or snails as attempts to cross an electrical pair will cause discomfort to the snails or slugs why they eventually will stop attempts to cross the 5 barriers. In this way an area delimited by the barrier 1 will be protected against intrusion from further snails and slugs.

The barrier 1, e.g. in the form of a hose is equipped with an even or odd number, however, minimum two separate, essentially parallel longitudinal areas/zones 10, 11, 12,

10 13 comprising an electrical conductive or semi conductive material, which is may be connected via electrical connection means as known in the art, in order to apply a voltage to the electrically conductive zones 10, 11, 12, 13 in such a way that an electrical voltage will be present between the said conductive or semi conductive areas/ zones 10, 11, 12, 13.

15

The hose will typically have a fixed cross sectional profile, which could be rounded, e.g. circular, but also oval, triangular, rectangular or another profile subject to the ground condition, placement or customer requests. Due to the flexible hose concept the barrier 1 may easily be laid out anywhere, e.g. in flowerbeds, on lawns, on flagstones, on asphalt

20 areas or on any hard of soft substrate/foundation. The barrier 1 may be laid out quickly and without use of tools, as the barrier does not need to be fastened to the ground, and it may very easily be lead around planting and other irregularities and also the hose to a large extent will adapt to broken ground. Besides it is very easy to move the barrier to other areas when needed, for instance when mowing the lawn or when removing unwanted

25 growth, which over time may appear in the immediate vicinity of the hose. The hose concept further makes the barrier 1 very resistant to mechanical action of animals or human beings that accidentally cannot damage the barrier. Cleaning the barrier from various kind of contamination, hereunder mucus from snails, snail excrements, dirt (earth), growth etc, is easily done by successive lifting the hose and wiping it with a piece

30 of cloth. Finally, the barrier 1 to some extent is self cleaning, as rain over time will wash away most impurities. Finally it may be noted that the hose concept provides a simple way to stow the barrier 1 away as it may easily be coiled up and put away for the next season.

The elongate member 30 of the barrier 1 may be manufactured by means of extrusion, 35 possibly followed by vulcanization in case of rubber material usage, whereby the barrier 1 is a hose with integrated conductors as a part thereof, makes the barrier 1 simple to manufacture by means of existing production techniques. In this way, and as opposed to fences based upon the above described known techniques, no mounting of the conductive elements/zones have to be performed subsequent to the production of the elongate member 30 of the barrier. The barrier 1 may in an alternative embodiment be manufactured as a corrugated hose, whereby the flexibility is increased, which would further ease the laying out of the barrier.

The elongate member 30 of the barrier 1 may be formed in plastic, a polymer material, or a rubber material, or a combination hereof. Trials have shown that such materials typically possess the requested electrical insulation properties, and will, in the right dimensions and material combinations, provide the flexibility necessary to form to the contours of the ground. As an example the elongate member 10 of the barrier 1 may be made of polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), thermo plastic elastomer (TPE), polycarbonate, polystyrene, polyurethane, PETG, ABS, EVA, rubber, EPDM, or silicone. Trials have shown that such materials typically possess the requested electrical insulation properties, and will in the right dimensions and material combinations provide the flexibility necessary to adapt to the contours of the ground.

The conductive or semi conductive zones 10, 11, 12, 13 may be formed by co-extrusion, gluing, painting, or coating, e.g. with one or more of the materials from the following list: Carbon, carbon fibers, gold, silver, cobber, steel, silver-plated glass, nickel, or aluminum.

More of the said conductive materials may be applied to the barrier by methods different from co-extrusion. The barrier 1 may be equipped with conductive areas by painting the surface of the elongate member 30 with conductive paint containing metal particles, for instance silver particles or such metals may be applied by a coating process. The conductive zones 10, 11, 12, 13 may be applied to the elongate element 30 as thin, elongate strips of metal foil, for instance cupper foil, which may be adhesive.

In other embodiments the elongate conductive zones 10, 11, 12, 13 may be formed in a conductive rubber. This would be beneficial when co-extruding the elongate member and the conductive zones. In yet an embodiment the conductive zones may be formed in a conductive rubber, having also an embedded metallic string, e.g. a cupper wire.

Trials have shown that the ideal material selection may ensure a sufficient conductivity without compromising the flexibility of the barrier 1. Practical trials have further shown that a hollow, corrugated or un-corrugated PE-hose with an outer diameter of approximately 30 mm (but also other widths) advantageously may be filled with water, sand, gravel or some polymer material. These materials are characterized by having a rather large density, whereby the hose to an even larger extent will adapt to irregularities of the ground, whereby the risk of undesired openings between the barrier 1 and the ground and thereby undesired barrier crossing is minimized. Usage of a filler material is judged to be an advantage in connection with all hoses in a light material, unless they in them selves are very flexible.

The slug barrier 1 may in be implemented with an even or odd number of conductors, which may then may be power supplied in pairs or partially or in whole separately in case the number of conductors exceed three. In some embodiments 8-24 conductors could be used, depending upon the hose width/diameter. This will protect the barrier against drop in protection level due to high electrical load caused by snail mucus, snail excrements, moisture, wet earth, plant remainders, dirt etc. The protection is provided by the fact that even if a few conductor pairs should be subject to short circuit or low resistance load, then there will still be a number of conductive pairs left, which will actively protect against crossing of the barrier 1. Moreover a larger number of conductor pairs/conductive zones will reduce the risk of unwanted passage of snails as they will be met by more conductor pairs if the manage to pass a single conductor pair. In practice the presence of more conductor pairs will mean an increased resistance against snail mucus and snail excrements for the barrier as a whole, because snails will only contaminate the area between two conductor zones if they have managed to pass the neighbor conductor pair. Conductor zone pairs distributed all the way around perimeter the barrier 1 will also protect against snails passing beneath the barrier in case of openings between the barrier and the ground. Furthermore a larger number of conductive zone pairs will reduce the likelihood of snails passing due to twisting of the hose, as another conductor pair will appear as a substitute for those pairs that are twisted away.

In order to verify the described effect and to be able to design the conductors on the hose in the best possible way regarding dimension and choice of material a number of measurements on a simple test set-up have been performed. The test set-up is shown in figure 3 and consists of a glass plate with a length of 500 mm. Two adhesive cobber bands each of 3.2 mm width have been glued to the glass plate with a distance of 10 mm. The behavior of the snails has been watched as a function of the applied voltage to the two bands. The experiment has been repeated for a number of different voltages varying from 0 Volt to 30 Volt.

Visually, a light discomfort in the snails may be observed already at 0.75 volt, in the form of a tendency to bend the body and to pull back eyes and horns. The snails, however, are crossing the two copper bands anyway without any provocation. At a voltage of 1.5 volt the discomfort has increased to an extent, where crossing does not seem to start unprovoked. The snails pull back after having touched the both copper band concurrently and cannot be provoked to perform a crossing. If a crossing has been started, however, at the time, when the voltage is applied, the snails continue and complete the crossing.

Raising the voltage to 3.0 volts creates a discomfort so large that any crossing is stopped. The snails again pull back after having touched the both copper band concurrently and cannot be provoked to perform a crossing. If a crossing has been started, however, at the time, when the voltage is applied, the snails continue and complete the crossing, if more than half of the crossing has been completed at the time of applying the voltage. In other words, the snails are not paralyzed by the voltage even though they are subject to relatively high current, when located in the middle of the two cupper bands.

At a voltage of 3.0 volt an increased amount of mucus is generated by the snails as a reaction to the voltage if this voltage is applied during the crossing. This phenomenon is not seen when applying a voltage of 1.5 volt and also not seen if the voltage of 3.0 volt has been applied before passing attempts have been made. The latter will be the normal case, if the barrier is constantly applied with a voltage, which is recommendable to avoid unnecessary mucus secretion. To avoid such secretion the applied voltage may upon start up be ramped up from 0 Volt to the normal voltage level over approximately 30 seconds.

The current has been measured to approximately 0.05 imA at a voltage of 1.5 volt corresponding to a conductivity of 1/ (30 kilo Ohm) for a slug starting a crossing. If the voltage is applied , when is slug is halfway over the barrier, the consumption is around 0.5 imA, corresponding to a conductivity of 1/ (3 kilo Ohm) which needs to be taken into consideration, when designing the conductive tracks, even though this should not happen under normal circumstances. Similar values for the conductivity are seen when applying a voltage below 3.0 Volt.

Voltage up 30 volt has been applied, but on the condition that this voltage is applied before a slug crossing is started no change in the behavior of the snails are noticed. In other words discomfort in the form of a tendency to bend the body and to pull back eyes and horns is still seen. The situation is different though, if the higher voltage is applied after a crossing has been started. In that case the slugs are paralyzed if the applied voltage is higher than about 9 volts. The crossing of the slugs will stop their movements, but will resume the crossing when the voltage is removed. If the voltage level reaches 30 volt the current through the slug is so high that the slugs are being killed after a short period of time.

In order to be able to judge the effect of the presence or larger amounts of slug mucus and slug excrements, approximately 15 slugs have been placed on the said glass plate (figure 3) and been provoked to cross the two copper bands several times without any voltage applied in order not to provoke any extraordinary mucus secretion. After about 50 crossings and when no slugs present between the copper bands a voltage of 3.0 Volt is applied and the current measured again. The current showed to be 0.5 imA, corresponding to a conductivity of 1/ (300 kilo Ohm) per mucus track or approximately 10 times lower than when a slug starts a crossing. The electrical load from a mucus track is therefore relatively low and this load disappears when drying out or when washed away by the rain. Mucus is therefore not seen as an important factor in relation to maintaining the function of the barrier. You should, however, assume that cleaning of the barrier by massive attacks from slugs will be necessary in order not to reduce the protective function of the barrier 1.

In order to be able to judge the effect on the barrier 1 from the weather and the characteristics of the ground the test setup shown in figure 3 have been laid out in heavy rain with the copper bands turned down on a lawn and afterwards the conductivity at a voltage of 3 volt has been measured and calculated to be around 1 / (20 kilo Ohm). If the test set-up prior to the lay out is impacted by slug mucus by letting around 100 slug passing the copper band, the conductivity increases to approximately 1/ (3 kilo Ohm) corresponding to 1/ (300 kilo Ohm) pr mucus track, which is consistent with the results found above. Again it is observed that the conductivity decreases to around 0, when the water has evaporated from the test setup, which confirms that slug mucus, when dry, does not constitute any electrical load.

Regarding the slug excrements 10 such pieces have been placed between the copper tracks on the glass plate. Immediately hereafter a voltage of 3.0 volt is applied to the copper tracks and the current was measured to 1.5 imA, corresponding to a conductivity of 1/ (2 kilo Ohm) or approximately 1/ (20 kilo Ohm) per slug excrement, which is comparable to the load of a slug when starting a crossing. Even if this load is higher than the load of a slug mucus track, the excrements will probably not result in any reduced function of the barrier. The reason for this is that observations have shown that slugs typically stops their crossing attempts before the rectum has reach a position, where excrements may cause an electrical load between 2 conductive tracks.

Based upon the above experiments performed at the described test-up, a functional model of the barrier 1 has been made. It consists of a corrugated plastic hose having a diameter of approximately 30 mm. Four pieces of cobber wire have been attached to the hose. The 4 cupper wires were in pairs applied with a voltage of 3.0 volt. The model was imposed to a massive slug attack, but no slug succeeded in passing the barrier. The finished product may be made in different embodiments. For ordinary garden owners e.g., the barrier hose may be designed as a very flexible, round, hollow, corrugated or un- corrugated hose with a diameter of 28 mm of poly ethylene with 8 longitudinal, conductive tracks equally distributed evenly around the perimeter of the hose. The width of each track is 8 mm and these are co-extruded into the surface of the corrugated hose. The conductive zones 10, 11, 12, 13 consist of polyethylene mixed with carbon formed over the conductive tracks. The hose is made with a non-corrugated adapter with a length of 22 mm and a diameter of 24 mm. Connection to a power supply is performed by means of a small coupling device of molded plastic, which makes contact to the conductive zones of the barrier by means of 8 copper springs. The system is supplied from 3 x 1.5 volt DC batteries. In another exemplary embodiment the barrier may be a 32 mm diameter cylindrical rubber hose with 6 conductive zones distributed evenly around the diameter.

E.g. for professional garden owners and nursery gardens the barrier may be made of vulcanized rubber of a diameter at 40 mm. Here the conductive zones may e.g. be made by painting 8 stripes of conductive paint on a hose, each stripe have a width of 12 mm. This hose is not so flexible, why it is most suitable for delimitation of larger, rectangular, flat areas without any major irregularities. Connection to an electrical power supply with an output voltage of 6 volt DC and input of 230 VAC, takes places by means of a molded connection part. The connection part may be made of hard rubber, containing 8 copper springs.

In the German patent DE 39 3001 3 Al, column 3, line 23 it is mentioned that a continuously applied voltage will paralyze the slug, which therefore cannot pull back, when it feel discomfort when touching two conductive tracks applied to a certain voltage. Such an effect has not been observed in connection with the described experiments, apart from a situation, where a voltage is not applied until crossing has actually been started and in case of the voltage being somewhat higher than 3 volt.

The basic principle of the slug barrier is to work as a barrier against slugs by making the slug feel discomfort, wherefore they will give up attempts to pass the barrier. The discomfort is not very severe and the slugs will generally not die from the effect of the barrier. As described, however, experiments have shown that the slugs will die after a short period of time, if the voltage level is increased sufficiently. This, however, requires that the voltage is applied during the crossing of the barrier or else the slug will just refrain from passing and pull back. Presumably the slugs will die though when just touching two conductors if the voltage is high enough. The voltage is in this case, however, supposed to be so high that it possibly would be dangerous to animals and human beings. Also such a high voltage would mean that grounding caused by contamination, hereunder slug mucus, rain water, growth etc would reduce the anticipated effect. If, however, an intermittent voltage is applied to the barrier, for instance with a duty cycle of 30 seconds, you would possibly reach a deadly effect with a relatively low voltage. It is assumed, though, that regular cleaning is then needed, at dead slugs will create a passage for living slugs, as the latter would then be able to climb over their dead fellow slugs.

The primary function of the slug barrier 1 is to provide a barrier against passage of slugs by means of an electrical voltage applied to two or more conductors causing discomfort to the slugs. In case the voltage disappears the barrier will also disappear without any visible, physical changes. This fact makes it relevant to consider to measure, register or in some other way handle or indicate any form of changes in the power consumption of, or voltage supply to, the barrier, for instance caused by short circuit or disconnection, regardless of the reason.

As described, the observations performed on the test setup have shown that the slugs are very sensitive to an electrical voltage, wherefore no special or dedicated power supplies are needed in order to reject the slugs when attempting to pass the barrier. The barrier may therefore be supplied directly or indirectly from one or more dry batteries, rechargeable batteries, transformers, and power supplies connected to 230 VAC or 400 VAC, power supplies secured against interruption (UPS), dynamos, solar cells or wind mills.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set.

The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

1. An electrical slug barrier (1) comprising

- a set of elongate electrically conductive zones (10, 11, 12, 13) arranged substantially in parallel;

- at least one electrically insulating zone (20, 21, 22, 23), formed between said electrically conductive zones (10, 11, 12, 13); said electrically conductive zones (10, 11, 12, 13) being connectable to a source of electrical energy in order to provide a voltage between each of said electrically conductive zones (10, 11, 12, 13), wherein said electrically conductive zones (10, 11, 12, 13) are arranged on, and along a longitudinal axis, A, of an elongate member (30) flexibly bendable in at least one first plane parallel to said longitudinal axis, A, and in another plane perpendicular to said first plane and parallel to said longitudinal axis A.

2. An electrical slug barrier (1) according to claim 1 wherein the elongate member has a maximum width perpendicular to said elongate axis A and a minimum width perpendicular to said elongate axis A, the ratio between the maximum width and the minimum width being in the range ¹Z--I.

3. An electrical slug barrier (1) according to claim 1 or 2, wherein the elongate member has an oval cross sectional shape.

4. An electrical slug barrier (1) according to claim 1 or 2, wherein the elongate member has a circular cross sectional shape.

5. An electrical slug barrier (1) according to any one of claims 1-3, wherein the elongate member is hollow.

6. An electrical slug barrier (1) according to any one of claims 1-5 wherein the flexible elongate member (30) is provided with two substantially parallelly arranged elongate electrically conductive zones (10, 11).

7. An electrical slug barrier (1) according to any one of claims 1-6 wherein the two substantially parallelly arranged elongate electrically conductive zones (10, 11) are arranged within an arc of 90° around a perimeter of the flexible elongate member (30).

8.An electrical slug barrier (1) according one of claims 1-5, wherein three or more substantially parallelly arranged elongate electrically conductive zones (10, 11, 12, 13) are arranged on and along the elongate member (30).

9. An electrical slug barrier (1) according to claim 8, wherein, the elongate electrically conductive zones (10, 11, 12, 13) are distributed around the entire perimeter of the elongate hollow member (30).

5 10. An electrical slug barrier (1) according to any of the preceding claims, wherein the elongate member (30) is a hose.

11. An electrical slug barrier (1) according to any of the preceding claims, wherein the elongate member (30) is formed in rubber.

10

12. An electrical slug barrier (1) according to any of the preceding claims, wherein the elongate member (30) is hollow and contains any or a combination of two or more of the materials comprising : Water, sand, gravel, pebbles, or polymer material.

15 13. An electrical slug barrier (1) according to any of the preceding claims, wherein a maximum width of the elongate hollow member (30) is in the interval 1-10 cm, such as 1.5-5 cm, such as 2-4 cm.

14. An electrical slug barrier (1) according to any of the preceding claims, wherein each of 20 the elongate electrically conductive zones (10, 11, 12, 13) has a width of 0.5-150 mm, such as 1-40 mm, such as 2-10 mm.

15. An electrical slug barrier (1) according to any of the preceding claims, wherein a width of each of the electrically insulating zones (20, 21, 22, 23) is less than 2 cm.

25

16. A kit comprising an electrical slug barrier (1) according to any of claims 1-15 and a processing unit connectable to said elongate electrical conductive zones (10, 11, 12, 13), said processing unit comprising means for measuring the voltage between the elongate electrical conductors (10, 11, 12, 13), and/or the power consumption of the elongate

30 electrical conductors (10, 11, 12, 13).

17. A kit according to claim 16, wherein the processing unit is further being adapted for regulating the power supply to the elongate electrical conductors (10, 11, 12, 13) in response to a change in power consumption of the elongate electrical conductors (10, 11,

35 12, 13).

18. A kit according to claim 16 or 16, wherein the processing unit is further adapted for registration and logging of changes in the power consumption of, or voltage supply to the elongate electrical conductive zones (10, 11, 12, 13), and/or where the processing unit further comprises acoustical or visual indication means for providing an acoustic or visual signal in response to changes in the power consumption of, or voltage supply to the elongate electrical conductors (10, 11, 12, 13), and/or where the processing unit further comprises means for transmitting data collected in response to changes in the power 5 consumption of, or voltage supply to the elongate electrical conductors (10, 11, 12, 13).

19. A kit according to any one of claims 15-18 wherein the processing unit is adapted to control a power supply to said electrically conductive zones such that a voltage is applied intermittently.

10

20. A method of preventing slug passage comprising the steps of providing an electrical slug barrier (1) according to any one of claims 1-16, - applying to said electrical slug barrier a voltage of 1-75 V.

15 21. A method according to claim 20 wherein said voltage is applied intermittently.

22. A method according to claim 21, wherein said voltage is applied with intervals of 10-60 seconds, such as 15 to 31 seconds, such as 30 seconds.

20 23. A method according to claim 21 or 22, wherein the voltage applied is in the order of 20-75V, such as 24-30V, such as 36-48V.