AU599754B2 - Retroreflective balls - Google Patents

Description

C.COHM ONWEALTH OF AUSTRALIA PATENT ACT 1952 COMPLETE SPECIFICATION 599754

(ORIGINAL)

FOR OFFICE USE

CLASS

INT. CLASS Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art-: i: At 4 00 NAME OF APPLICANT: ADDRESS OF APPLICANT: NAME(S) OF INVENTOR(S) .DUNLOP LIMITED Silvertown House, Vincent Square, London SW1P .2PL, England Royce PRIDGEON ADDRESS FOR SERVICE: DAVIES COLLISON, Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: "RETROREFLECTIVE BALLS" The following statement is a full description of this invention, including the best method of perforing.it known to us -1-

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RETROREFLECTIVE BALLS This invention relates to retroreflective games balls.

It is well known to enhance the visibility of a games ball, particularly when the movement of the ball in play is to 0 be televised or otherwise monitored by a camera, by providing on 0 00 0 o 0 or below the periphery of the ball one or more portions of a 0 0 retroreflective material. In particular, the published GO 0 0 Application GB 2145337.A discloses a means of providing the o spherical outer surface of a ball with a plurality of radially- -extending cavities in which one or more of the cavities contain 0 0 a portion of a retroreflective material attached to the base of 0 0 4 0 00 the cavity. The aforesaid GB 2145337.A also discloses a hollow 00 00 ball made of a transparent material and having a retroreflective surface applied to the spherical inner surface of the ball.

4 Clearly, the retroreflective portions applied to such prior-known balls must be of planar or convex configuration.

When such a ball is played in a beam of incident light emanating from a source substantially behind the player, there will be at any given instant some proportion of the reflective areas illuminated by the beam of light which cannot reflect the incident light back towards the player, (or to a television camera adjacent to the source of light) because the planar or convex reflecting surfaces are angled significantly to the p i 2 1 incident beam. These portions of the reflective areas are 2 those which are towards the edge of the, projected area of 3 the ball and so the apparent size of the ball, as indicated 4 by reflected light, is smaller than the actual size of the ball.

6 7 Also, if the planar or convex portions of 8 retroreflective material are recessed below the surface of 9 the ball (as is desirable so that the ball's playing properties are not impaired) then further restriction of 11 reflected light occurs due to the fact that, towards the 12 edge of projected area of the ball, the edge of the recess 13 further restricts the amount of reflected light.

14 Consequently, the apparent size of the ball, as indicated by the amount of light reflected from the ball, is further 16 reduced.

o o 17 18 This, in turn, results in reduced visibility of the 19 ball in play.

21 We have now found that the visibility of the ball in .0 22 play can be considerably enhanced by making the 23 retroreflective surface concave relative to the outer So 24 surface of the ball.

oo 0 26 Accordingly, the present invention provides a games 27 ball made of rubber or a rubber-like material having a o 28 plurality of radially-extending cavities uniformly 29 distributed over the outer periphery of said ball, in which any one or more of said cavities contains a portion of a 31 retroreflective material, each said portion lying below and 32 being of substantially concave configuration relative to the 33 outer periphery of said ball.

34 In a preferred embodiment of the present invention, 36 the ball is, for example, a squash ball.

37 38 900308.kxlspe.003,btr. 2 3 o o r C 0. 0 0 o 0I 0 1) 0 o 00 0 0, Preferably, the concave retroreflective portions are attached to the base and sides of the cavities by means of an adhesive.

The retroreflective portions may suitably be made of a laminar material comprising a retroreflective element and an adhesive element.

The concave configuration of the retroreflective portions causes incident light to be reflected to the camera or other monitor over a wider area of the surface of the ball than would be the case where the retroreflective portions are planar or convex. Thus, the effective ball diameter (as "seen" by the camera or other monitor) is increased and the visibility of the 900308.kxlspe.003,btr,3 L. i ball is enhanced.

The present invention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings on 6In the drawings (wherein like numerals denote like 0 0 parts) 0 0 0 o 0 o; Figure 1 is a perspective view of part of a squash ball 0,00,.

according to the present invention; S °Figure 2 is a section on line II II of Figure 1; o 00 S° Figure 3 is an enlarged view of a portion of Figure 2; Figure 4 is a comparable view of a portion of a prior- -known ball provided with planar retroreflective portions.

A squash ball 10 is provided with a plurality of radially-extending cavities 11 uniformly distributed over its outer periphery. A random selection of these cavities (four are indicated at 110, 111, 112 and 113) each contain a concave retroreflective member (201, 202, 203 and 204 respectively) bonded to the base and sides of the cavity.

Incident light I is reflected, as shown by arrow R,to a camera or other monitor (shown schematically at The concave retroreflective portion 204 reflects the light to the monitor to a greater extent than the planar retroreflective portion shown in Figure 4 and thus enhances the visibility of the ball in play.

o While the present invention has been described herein a with particular reference to a squash ball, it is not to be 0 0 0 0 construed as being limited thereto.

0 o Further, although the present invention has been Sdescribed herein in terms of planar reflection, it is to be understood that the concave retroreflective portions give rise o00 0 o to a "cone" of reflected light in which the angle subtended by the "cone" amounts to a few degrees. Thus, while there will inevitably be some "scatter" of the reflected light, this will be considerably reduced in comparison with that of prior-known retroreflective balls using planar or convex reflectors.

ISC/RACK/10450 L