US Patent 4,177,994
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
An apparatus for simulating the game of golf and aiding golfers in improving their game by providing an indoor practice facility. The apparatus employs a unique penetrable grid consisting of parallel spaced-apart conductors in one plane positioned ahead of a second group of conductors in a second plane parallel to the first plane. The conductors are connected in an electrical circuit, and when the grid is struck by a golf ball, a conductor in one group engages a conductor in the other group thereby producing a signal that is used to provide an accurate measurement of the direction and velocity of the golf shot. The electrical circuit includes diodes and electrical connections to a units lead and a tens lead. Each pair of units and ten leads is connected to the detecting means. The detecting means includes latches to detect the contact of the first ones of the conductors in the first and second planes. A screen is positioned behind the penetrable grid in order to stop the flight of driven golf balls, and provide a surface on which images of a golf course may be projected. Using this apparatus, the lie of the golf ball resulting from that shot can be predicted and plotted on a map of the golf course. The basic procedure employed using the apparatus can be repeated to simulate play over an entire golf course.
Lindquist, Everet F. Golf game and practice apparatus. US Patent 4,177,994 filed December 20, 1976 and issued December 11, 1979. https://ir.uiowa.edu/patents/18