A variable-color region (106) of an information-presentation structure extends to an exposed surface (102) at a surface zone (112) and normally appears along it as a principal color. An object-tracking control apparatus (808) tracks movement of an object (104) over the surface. As the object impacts the zone at an object-contact area (116), an impact-dependent portion (138) of the VC region temporarily appears along a print area (118) of the zone as changed color materially different from the principal color if the impact meets threshold impact criteria and if the tracking indicates that the object is highly likely to impact the object-contact area. The print area closely matches the object-contact area in size, shape, and location. Impacts of bodies not tracked by the control apparatus substantially do not cause color change so that color change occurs substantially only for suitable impacts of the tracked object.

Disclosed is system and method for measuring the tension of a tennis net, and, alternatively or in addition, for determining if a service let occurs via the measuring of the net tension. The disclosed embodiments measure a force exerted on the center-strap or the singles stick by the net. In these embodiments, the measured force provides an accurate reflection of the tension of the net.

The invention is a foot-race game and associated apparatus which allows play by an individual or between a group of individuals or teams. The apparatus which is used in conjunction with the game employs physical base locations, where each base location is in communication with a computer. The computer issues commands for the base locations to emit one-colored light where different base locations emit different light colors corresponding to light colors assigned to different players. Before the game each player is assigned a color and must run to the base location emitting his color. The computer randomly shifts colors between base locations so that the player must chase his color between base locations as the game is played.

A golf device including a first elongated portion. The golf device may include a second elongated portion. The golf device may include an arch portion slideably engageable inside the first elongated portion and the second elongated portion.

A golf device including a first elongated portion. The golf device may include a second elongated portion. The golf device may include an arch portion slideably engageable inside the first elongated portion and the second elongated portion.

Disclosed is system and method for measuring the tension of a tennis net, and, alternatively or in addition, for determining if a service let occurs via the measuring of the net tension. The disclosed embodiments measure a force exerted on the center-strap or the singles stick by the net. In these embodiments, the measured force provides an accurate reflection of the tension of the net.

A variable-color region (106) of an information-presentation structure extends to an exposed surface (102) at a surface zone (112) and normally appears along it as a principal color. An impact-dependent portion (138) of the variable-color region responds to an object (104) impacting the zone at an object-contact area (116) by temporarily appearing along a print area (118) of the zone as generic changed color materially different from the principal color. The print area closely matches the object-contact area in size, shape, and location. The threshold impact criteria consist of multiple sets of different threshold impact criteria respectively associated with multiple specific changed colors materially different from the principal color. If the impact meets the threshold impact criteria, the generic changed color is the specific changed color for the criteria set met by the impact.

A variable-color region (106) of an information-presentation structure extends to an exposed surface (102) at a surface zone (112) and normally appears along it as a principal color. An impact-dependent portion (138) of the variable-color region responds to an object (104) impacting the zone at an object-contact area (116) by temporarily appearing along a print area (118) of the zone as generic changed color materially different from the principal color. The print area closely matches the object-contact area in size, shape, and location. Sound-generating apparatus (602 or 702) selectively generates a specified audible sound in response to the object impacting the object-contact area so as to meet the threshold impact criteria. The specified sound is separate from any audible sound originating at the object-contact area due physically to the impact.

A variable-color region (106) of a sports-playing structure of an information-presentation structure extends to an exposed surface (102) at a surface zone (112), normally appears along it as a principal color, and includes impact-sensitive and color-change components (182 and 184). A boundary line (1306/1308 or 1386/1388) extends along an in-bounds area (1302 or 1382) of the surface. A segment (192) of the impact-sensitive component responds to an object (104) impacting the zone at an object-contact area (116) by providing an impact effect if the impact meets threshold impact criteria. A segment (194) of the color-change component responds to the impact effect by causing an impact-dependent portion (138) of the region to temporarily appear along a print area (118) of the zone as changed color materially different from the principal color. The zone typically adjoins the boundary line or an internal line (1334 or 1396).

A variable-color region (106) of a football-playing or baseball/softball-playing structure of an information-presentation structure extends to an exposed surface (102) at a surface zone (112) and normally appears along it as a principal color. An impact-dependent portion (138) of the variable-color region responds to an object (104) impacting the zone at an object-contact area (116) by temporarily appearing along a closely matching print area (118) of the zone as changed color materially different from the principal color. For football, the zone typically adjoins an end or side line (1446 or 1448) to help determine whether the object, typically a person's shoe, impacted the surface in or out. For baseball/softball, the zone typically adjoins a foul line (1506) to help determine whether the object, a baseball/softball, impacted the surface fair or foul.