GB2143141A - Dartboards - Google Patents

Abstract

A dartboard for automatic scoring detectors comprises inserts 3 in the target areas, the inserts responding more than a base 2 to an effect produced by a dart hitting the target, the inserts being bonded to the base with corresponding cavities for receiving the inserts. Effects made by darts may be sensed electrically by means of piezo-electric material infusions in the inserts, magnetically by means of infusions with magnetically permeable material, mechanically by means of materials differentially improving the propagation speed or reducing the damping factor in the said inserts, or electro-magnatically by altering tuned circuits of which the inserts form a part. <IMAGE>

Description

SPECIFICATION Dartboard for Automatic Scoring Circuits This invention relates to design details of a multiple material dartboard and the manner of producing it in large quantities in order to provide the best possible preconditions for identifying the board sectors upon which a dart has been successfully thrown, by electronic sensors. The circuit principles for such a system have already been described in our patent applications 8035320 and 8039384. However, the detail design of the multiple-material board for magnetic detection was still rudimentary and would in practice have relied too much on the refinement and accurate adjustment of the electronic sensor circuitry.

Since it is desirable to keep this circuitry as simple and inexpensive as possible it is necessary to optimize the board structure so that reliable 'yes--no' outputs are obtained from target sectors and thereto adjacent sectors, even before they are processed by the electronic circuit. This is achieved by an amalgamated material design consisting of an active rump section having cavities into which the active substances are pressed or cast. The composition of the two or more substances may with advantage be nearly the same so as to promote the interlocking of the two portions into a single dart board.

Contrary to the earlier descriptions, the activated portion constitutes that part of the board on which darts are thrown (even though they may at times penetrate into the inactive portion as well), and the aim of the invention is to form out the active portions so that they are a continuous pulse-conductive zone between the dart impact area of the board surface and the transducers or sensors concerned which are mounted to or close to the rear of the board.

The invention is explained by an example which is based on magnetic induction techniques but other techniques may be used in order to adapt rationally to different sensors such as will also be briefly discussed at the end of this paper.

The description is aided by drawings in which Fig. 1 is a top view of one of the board sectors (c-c) Fig. 2 is a radial cross section (A-A) Fig. 3 is a tangential cross section (B-B) Figure 2 shows the rump section (2) of the board which is pressed out as an independent component. Thereafter, material infused with ferrite dust or mixed with flexible ferrite or the like, is cast or pressed unto areas marked with the index (3), with accompaniment perhaps of additional heat, and bonded to the rump (2) so that the two portions constitute one single component. It would be feasible to pre-fabricate the portions (3) as finished elements which then would be placed into the accurately matching cavities of the rump body and bonded with the aid of some bonding medium.

One further feature of the rump portion (2) is that the section dividers (1 a to 1 g, Fig. 1) are set into narrow grooves. These can also be seen in Figures 2 and 3. There are, however, several ways of locating the divider lengths on the board; one is to surface-mount them. Another is to make the width of the section dividers about equal with the thickness of the board so that they penetrate right to the bottom. This would lessen the compression effect upon the board face caused by the repeated impact upon the divider by darts. The dividers may be either embedded into the board so that they remain slightly below the board surface, or they may be flash with it, or protrude from it.

Inverted T sections may be used.

At the bottom of the insert portion (3) is an opening in rump part (2) through which coil cores (4) protrude. These may be made of soft iron riveted to the base plate 7 which acts as a magnetic sink. The coils (5) are uniform for all the segments (except coil 5a) and these can therefore be mass produced at a low cost. The number of turns may be less than in the previously described versions because the novel board structure permits higher flux changes on arrival of a dart.

Coils may be earthed on one side leaving oniy one other coil end to be connected to shielded wires (9) which connect to the analyzer printed circuit board (details of which were given in the cited patent applications).

There is a narrow strip of neutral board material (2) on both sides of the section dividers (1). This separation layer increases the difference between the magnetic flux of the targeted sector and a neighbouring sector. If the dart hits the neutral strip (2) close to the section dividers, this will not prevent the differential action in the analyzer. In addtion, the field directed towards the non-targeted portion (3) is partly shielded and made less effective by the section divider if it is made from steel.

Where an arrow or dart arrives at an angle in such a manner that it first penetrates the targeted active portion (3) but then proceeds to undercut the wire (1) here used as a section divider and penetrates part of the non-targeted active area (3), one may first believe that this shot would be wrongly recorded. It must, however, be remembered that the targeted area is hit first, and consequently a circuit such as already described for impulse sensing methods, would be able to lock safely into the correct output before the second output can do any harm.

Finally, mention should be made of the described board structure becoming useful not merely in conjunction with the system of using magnetically polarised darts but also in conjunction with other active materials employed for the board portions (3). For example, one may have piezoelectric dust immersed in these portions together with carbon to make the sectors conductive. When an arrow hits the piezoelectric dust it will release an electric charge which would be transported to an electrode attached to the rear of the section and from there by a wire (9) inputted to the electronic analyzer. Incidentally, in this context, the section dividers would be made from non-conductive material.

Another approach may be to choose the material for portions (3) so as to give it a substantially smaller internal damping factor for propagated waves than the damping factor for the rump sections (2). When then an integrated pressure sensor is attached to a portion (3), electronic identification of the targeted section would be possible.

Another way of using magnetic detection would be to polarize the coil cores (4) by means of permanent magnet disks attached to them or by including into them cylindrical magnets. A dart having a magnetizable dart pin, on approaching a targeted board section, in spite of being nonmagnetic, would excite in the coil (5) an induction voltage.

Still another way would be to make the described coils part of tuned circuits, for example tuned to a local radio station or to a small HF oscillator integrated into the board system. A dart hitting a section (3) which in this case would be part of the tuned coil, would cause the tuned coil circuit to be affected, detuned and producing noise modulation; this would be detectable by conventional diode detector circuits and could be used as a scoring signal.

Claims (9)

1. A dart board for automatic scoring circuits, characterized by its composition of bondable portions, a rump portion (2) with cavities opening towards the frontside of the board, and active portions (3) placed into said cavities which act as preferential conductors for effects produced by darts approaching or hitting a targeted sector whereas the said rump portion acts as a relative non-conductor for these effects.

2. A dart board for automatic scoring circuits as in claim 1 wherein the rump portion has grooves at its upper surface coinciding essentiaily with the upper board surface wherein partitioning elements (1) made of a material having certain different properties from that of the board, are embedded to mark the frontiers between neighbouring target sections.

3. A dart board for automatic scoring circuits as in claim 1 wherein the rump portion has component inserts upon which the partitioning elements (1) may be surface mounted.

4. A dart board for automatic scoring circuits as in claims 1, 2 and 3 wherein the active portions (3) consist of a substance infused with magnetically permeable material and the partitioning elements consist of steel wire.

5. A dart board for automatic scoring circuits as in claims 1, 2 and 3 wherein the active portions (3) consist of a substance infused with conductive dust or made conductive in some other way, as well as piezoelectric particles, and wherein the partitioning elements (1) consist of an electrically non-conductive material, or a material covered by non-conductive layers.

6. A dart board for automatic scoring circuits as in claim 1 wherein the active portions consist of a material having a smaller damping coefficient or a higher pulse propagation speed than the surrounding material of the rump section.

7. A dart board for automatic scoring circuits as in claims 1 and 4 wherein the bottom of the rear part of each active portion (3) is in contact with a coil core (4), one side of which is fixed to a magnetic sink plate (7).

8. A dart board for automatic scoring circuits as in claim 7 wherein the said coil cores (4), or part of their length, is made of magnetically retentive material endowing each associated "active" portion (3) with a magnetic bias.

9. A dart board as in Claim 1 wherein the insert portions (3) are made of magnetically permeable material and wherein the coil sensors (5) form part of a circuit tuned to electromagnetic waves directed at or penetrating the board area, and which coils circuits comprise detectors to detect the changes in the tuned condition produced by a dart in the target area.