Patent ID: 8713808
Filing Date: 2014-05-06
Classification: A63C

Abstract:
1. An apparatus for providing a temporary visible reference line across a surface, comprising: a movable structure dimensioned and arranged to be supported by and project upwardly from an athletic field surface; a laser source supported by the movable structure, the laser source being positionable at an elevated location relative to the athletic field surface and operative to direct optical energy at a wavelength of between 380 nm and 750 nm upon the athletic field surface while said movable structure is maintained substantially in a first orientation relative to the athletic field surface; a position sensing system operative to determine when said movable structure is no longer maintained substantially in the first orientation; a safety switch operative to disable the laser source when said movable structure is no longer maintained substantially in the first orientation; and a collision detection system adapted to sense an impending collision with a rapidly approaching player, said safety switch being responsive to the collision detection system to disable to the laser source before such collision occurs.