| 摘要 |
A tennis ball having a cover and a multiplicity of electrically conductive fibers which are incorporated with the cover and which have portions extending on the outer surface of the cover to effectively render the ball's outer surface electrically conductive, whereby said ball is capable of completing an electrical circuit across spaced apart electrical conductors lying in a selected area on a tennis court for the purpose of detecting or sensing touchdown of the ball in said area. The electrically conductive fibers may be needle punched through the cover and they may be formed by coating synthetic fibers with an electrically conductive material such as a tin-containing oxide, or silver-plated nylon fibers may be used. An electrically conductive scrim or open mesh of fibers may be located along the inner surface of the cover to provide needed conductivity. A sulphur-free adhesive may be used to secure the cover to the ball.
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