Abstract: Systems for automatically determining whether a conductive, volant game device touches down in bounds or out of bounds on a playing surface. The system includes boundary line and out of bounds circuits which can be completed by the touchdown of the game device thereupon. A control unit processes the signal generated by each completed circuit and turns on a signal which is coded to indicate whether the device touched down in bounds or out of bounds. Associated circuits and control capabilities provide a signal when the game device touches the top of a net or other barrier in games in which that type of contact is significant.

Abstract: An electrically conductive tennis ball comprising a cover of woven fabric in which the yarn used for weaving the fabric in at least one direction is made by twisting together a blend of electrically conductive and electrically nonconductive filament fibers. The electrically nonconductive fibers may predominate, and the woof yarn may be thicker than the warp yarn which may be so woven with the woof yarn that the latter occupies the major part of the ball's surface. To promote continuity of the electrical paths in the ball's cover, an electrically conductive adhesive, or mat, or scrim or other base may be interposed between the woven cover, and an electrically conductive coating may be applied to the inner, or back, side of the cover. Needling may also be employed to reorient the fibers in the cover and thereby enhance the conductivity of the electrical paths along the inner side of the cover.

Abstract: 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.

Abstract: A ball for playing a game, such as tennis, and having a plurality of unwoven electrical conductive networks which are formed by electrically conductive fibers and which extend at least partially on the outer surface of the ball. The ball is made by first needle punching an unwoven open mesh of electrically conductive fibers into the cloth cover of the ball, and then adhering the cover to the ball core so that the open mesh is positioned between the core and the cover.

Abstract: 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 sulfur-free adhesive may be used to secure the cover to the ball.

Abstract: An anti-copying system or method of coloring an original document with pre-selected background and image colors which, in combination, inhibit or prevent intelligible reproduction on xerographic and electrostatic copying machines.

Abstract: A tennis scorekeeping device having a pair of separately formed scorekeeping units adapted to be mounted one each side of a tennis racquet handle between the head of the racquet and the handle grip of the racquet, first manually manipulatable means on one of said units for scoring game points won by opposing players, and second manually manipulatable means on the other of said units for scoring the games won by opposing players.

Abstract: A gaming surface contact detecting system for detecting the presence of a particular type of projectile upon touchdown of the projectile on any gaming surface or surfaces and for locating the position of touchdown of the projectile in relation to the gaming surface or surfaces. The gaming surface contact detecting system includes a projectile with at least one surface portion of detectable material, and a surface signal means. The surface portion of the projectile may include a contact recognition surface such as a chemical surface or an electrical conductive surface. The surface signal means may include a second chemical surface or may include a sensing means. The surface signal means is connected on at least a portion of the gaming surface. Upon positive contact between the projectile and the surface signaling means, a signal is initiated that signals the touchdown of the projectile that bounces off the surface signaling means on the gaming surface.