WO1995004912A1

WO1995004912A1 - Target

Info

Publication number: WO1995004912A1
Application number: PCT/GB1994/001738
Authority: WO
Inventors: Anthony Thomas Wilson
Original assignee: Target Marketing Limited
Priority date: 1993-08-09
Filing date: 1994-08-08
Publication date: 1995-02-16
Also published as: GB9316480D0

Abstract

For rendering electrically conductive the front layer (1) of each of twenty five sisal biscuits (2) to an approximate depth (3) equivalent to a third of its thickness (4), each is treated with a metered and sprayed application of aqueous coagulant of graphite (7). After drying, the biscuits are placed in a press to compress them into a target disc (11), having a conductive front layer (12) extending from its front face (13) to approximately one third of the depth of the disc. The disc (11) is then bonded to a chipboard backing (14) and encircled by a nylon coated metal strap (15). An insulating divider (21) is offered up to the disc (11) and backing (14) and pressed into the front layer of the disc. For use of the target in a dart machine, contact can be made with the beds by inserting respective contact pins (26) through the chipboard backing as far as the front layer (12).

Description

TARGET

The present invention relates to a target particularly, but not exclusively, for use as a dart board or bed in an automatic darts game machine (the Production Machine), such as described in International Application No. PCT/GB93/01671, published under No WO 94/04883 on 3rd March 1994.

The Production Machine is an improvement on the machine (the Original Machine) described in International application No.PCT/GB83/00264, published under No. WO 84/01618 on 26th April 1984.

The dart head (the Existing Dart Head) used in the

Original Machine and indeed the Production Machine comprises a plurality of sections or beds, representing the different scoring areas of a dart board, each made of electrically conductive material and inserted in an insulating frame. The beds are individually electrically connected to scoring equipment of the machine. The beds are of compressed sisal, which has been treated to make it conductive.

Fabrication of the beds is similar to the method used in the manufacture of conventional dart boards. Some twenty five biscuits of sisal, that is 7" (175mm) diameter bundles of sisal are compressed both laterally and longitudinally to dart board size. In the Existing Dart Head, the sisal has been previously treated to render the fibres conductive, by immersion in graphite bearing liquid. After compression, the sisal is bonded to pieces of plywood having the shape of the finished dart head beds. Once the bonding adhesive has set, the individual beds are separated and assembled into a frame. The Existing Dart Head suffers from a number of disadvantages, amongst which are the need to keep the individual beds electrically separate in an expensive and intricate frame, which is an injection moulding. Further, certain of the beds, particularly those having narrow portions are difficult to insert in the frame with com¬ pression of the sisal such that the darts can be retained in the less compressed areas without risk of falling out. This problem is aggravated by the moulding draft on the frame.

A further disadvantage of the Existing Dart Head is its means of electrical connection to dart detection circuitry, namely use of screws passing through the moulded frame into the individual beds. Connection wires make contact with the screws.

The object of the present invention is to provide an improved dart head.

According to one aspect of the invention, there is provided a target comprised of: a disc of fibrous material having an electrically conductive front layer, and a bed divider inserted into the disc to separate divided, conductive beds from each other, at least at the front conductive layer of the disc.

Normally the disc will having a backing sheet, preferably of wooden board, such as plywood or chipboard.

Whilst the disk may be conductive throughout its depth, in which case the bed divider will extend throughout the depth of the bed; it preferably has a non-conductive back layer, and the divider need not extend to the full depth of the disc. The non-conductive back layer enhances insulation σf the beds from each other, particularly in lessening the chance of a conductive fibre misplaced in insertion of the divider extending from one bed to another.

The divider can be an injection moulding of hard plastics material. It may carry externally conductive strips, or a conventional dart board wire, which are grounded in use.

For use, the individual beds can have electrical contact made to them in a manner analogous to that of the Existing Dart Head by insertion of screws through the disc's backing sheet and the back layer of the disc as far as the conductive part of the beds in the front layer of the disc. However in the preferred embodiment, the backing sheet is pre-drilled at contact points, through which contact pins mounted in the darts game machine are inserted on assembly of the target to the machine. This arrangement has the advantage of enabling the target to be withdrawn from the machine, rotated to bring little used beds to the position of the often used beds and remounted in the machine.

According to a second aspect of the invention there is aprovided a darts game machine for use with the target of the first aspect, the machine having an array of contact pins arranged to contact the beds of the target through the backing sheet apertures and connected to dart detection circuitry of the machine.

Preferably the pins are arranged to project from a contact board against which the target's backing sheet lies when the target is assembled into the machine. Further it is preferred that the machine includes clips for clipping the target in its assembled position at an angle selectable in accordance with wear of the beds of the target. According to a third aspect of the invention there is provided a method of constructing a target consisting in the steps of: assembling a compressed fibre disc having an electrically conductive front layer, and inserting a bed divider into the disc to separate divided beds from each other, at least at the front conductive layer of the disc.

Preferably, the fibre disc is bonded to a backing sheet prior to insertion of the bed divider; and in the preferred embodiment, an array of apertures is formed in the backing sheet in correspondence with the divided beds.

The disc can be cut by a knife in the shape of the divider. The knife is withdrawn and the divider inserted in its place. This is particularly suitable where the divider is of plastics material.

The disc may be rendered conductive in its front layer after the fibres have been compressed. However, the depth of conductivity can be more readily controlled by impreg¬ nating the fibres, preferably sisal as used previously, before they are compressed, that is when they are in biscuits. Typically the fibres are 18mm long and for impregnation are immersed to a depth of 6mm, that is about a third of the thickness of the biscuits, in a liquid rendering the immersed part of the fibres conductive. Acceptable results can be expected with immersion of between a quarter and a half of the thickness of the uncompressed fibre. Alternatively, as is preferred, the liquid can be sprayed onto the exposed end of each biscuit. Preferably, the liquid is an aqueous coagulant of graphite. The divider is inserted from the front face of the disc and through the front layer at least as deep as the conductive front layer's extent.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic cross-sectional view of a sisal biscuit being treated to render part of it conductive for use in constructing a target in accordance with the invention;

Figure 2 is a plan view of the constructed target; Figure 3 is a cross-sectional view of the constructed target, taken on the line III-III in Figure 2 and mounted in a dart game machine shown in scrap detail; and

Figure 4 is a scrap view on a larger scale of a detail from Figure 3.

For rendering electrically conductive the front layer 1 of each of twenty five sisal biscuits 2 to an approximate depth 3 equivalent to a third of its thickness 4, each is treated with a metered and sprayed application of aqueous coagulant of graphite 7. After drying, the biscuits are placed in a press to compress them into a target disc 11, having a conductive front layer 12 extending from its front face 13 to approximately one third of the depth of the disc. The disc 11 is then bonded to a chipboard backing 14 and encircled by a nylon coated metal strap 15.

A divider 21 in the plan form of a conventional dart board wire of hard, injection moulded, plastics material such as glass filled ABS has sharp edges 22. As shown in the drawings, on the exposed, external surfaces 24 of the divider opposite from the sharp edges, the divider has throughout its extent grooves 23 for conductive strips 26 normally of metal. The strips are connected together and grounded to assist operation of the detection circuitry as described in International Publication No WO 94/04883. However it should be noted that it has been discovered that this feature is not strictly necessary.

The divider 21 is offered up to the disc 11 and backing 14 and pressed into the front layer of the disc. The depth of the divider - between its sharp edges 22 and its exposed surfaces 24 is such that with the surfaces 24 just proud of the front face 13 of disc, the sharp edges do no cut into the chipboard backing, but the bed divider extends through the front, conductive layer 12 of the disc 11; whereby the individual beds 25 are electrically isolated from each other.

Prior to bonding of the fibre disc 11 to the chipboard backing 14, the latter is pre-drilled with an array of holes 27, each corresponding to one of the beds 25. After bonding, the holes are cleared of adhesive which may be obstructing them.

For use of the target in a dart machine, contact can be made with the beds by inserting respective contact pins 26 through the chipboard backing as far as the front layer 12. The contact pins are fixed in a contact board 29 in the machine. The target is pressed onto the pins with the backing 14 coming to lie against the contact board. Detection circuitry 30 of the dart machine is connected to the pins and thence to the respective beds by respective wires 31. Clips 32 hold the target in place in the machine.

After use of the target for some time, certain of the beds will have been heavily aimed at and liable to deteriorate first. To extend the useful life of the target. it can be removed from the machine and angularly repositioned on the contact board and its pins with relatively unused beds in the position of the heavily used beds.

The invention is not intended to be restricted to the details of the above described embodiment. For instance, prior to insertion of the divider 21, the fibre disc 11 may be pre-cut with a knife having the pattern of the divider to assist insertion of the divider.

Claims

CLAIMS:

1. A target comprising: a disc of fibrous material having an electrically conductive front layer, and a bed divider inserted into the disc to separate divided, conductive beds from each other, at least at the front conductive layer of the disc.

2. A target as claimed in claim 1, including a backing sheet, preferably of wooden board.

3. A target as claimed in claim 2 , wherein the fibre disc is conductive throughout its depth and the bed divider extends throughout the depth of the bed.

4. A target as claimed in claim 3, wherein the fibre disc has a non-conductive back layer, and the divider preferably does not extend to the full depth of the disc.

5. A target as claimed in any preceding claim, wherein the divider is an injection moulding of hard plastics material.

6. A target as claimed in claim 5, wherein the divider carries externally an array of conductive elements, which are adapted to be grounded in use.

7. A target as claimed in claim 2 or any one of claims 3 to 6 as appendant to claim 2, wherein the backing sheet has apertures at contact points arrayed in correspondence with the divided beds of the target, through which apertures contact pins mounted in a darts game machine can be inserted on assembly of the target to the machine.

8. A darts game machine for use with the target of claim 7, the machine having an array of contact pins arranged to contact the beds of the target through the backing sheet apertures and connected to dart detection circuitry of the machine.

9. A darts game machine as claimed in claim 8, wherein the pins are arranged to project from a contact board against which the target's backing sheet lies when the target is assembled into the machine.

10. A darts game machine as claimed in claim 9, including clips for clipping the target in its assembled position at an angle selectable in accordance with wear of the beds of the target.

11. A method of constructing a target consisting in the steps of: assembling a compressed fibre disc having an electrically conductive front layer, and inserting a bed divider into the disc to separate divided beds from each other, at least at the front conductive layer of the disc.

12. A method of constructing a target as claimed in claim

11, wherein the divider is inserted from the front face of the fibre disc and through the front layer at least as deep as the conductive front layer's extent.

13. A method of constructing a target as claimed in claim 11 or claim 12, including the step preliminary to inserting the divider of cutting the fibre disc with a knife in the shape of the divider.

14. A method of constructing a target as claimed in claim 11, claim 12 or claim 13, wherein the front layer of fibres of the disc are rendered conductive prior to their compression into the disc by immersion to a selected depth in a liquid rendering the immersed part of the fibres conductive.

15. A method of constructing a target as claimed in claim

14. wherein the depth of immersion is between a quarter and a half of the uncompressed length thickness of the fibre disc.

16. A method of constructing a target as claimed in claim 11, claim 12 or claim 13, wherein the front layer of fibres of the disc are rendered conductive prior to their compression into the disc by spraying with a liquid rendering the front layer of the fibres conductive.

17. A method of constructing a target as claimed in claim 14, claim 15 or claim 16, wherein the liquid is an aqueous coagulant of graphite.

18. A method of constructing a target as claimed in claim any one of claims 11 to 17, wherein the fibre disc is bonded to a backing sheet prior to insertion of the bed divider.

19. A method of constructing a target as claimed in claim 18, including forming an array of apertures in the backing sheet in correspondence with the divided beds.