초록 ▼

A method of determining in a game of tennis the point of contact of a service ball relative to a service line by (a) monitoring a field of view along the service line and producing an electronic representation of an upper boundary of the ball as it passes through the field of view, (b) scanning the

A method of determining in a game of tennis the point of contact of a service ball relative to a service line by (a) monitoring a field of view along the service line and producing an electronic representation of an upper boundary of the ball as it passes through the field of view, (b) scanning the upper boundary of that representation progressively in the direction of the ball flight and determining at successive spaced positions along the path of the ball the angle of definition of the boundary, and (c) comparing successive values of that angle and noting the position of the ball at which that angle reduces relatively rapidly to a lower or even a negative value. A preferred method determines and compares successive horizontal components of successive sections of the boundary which have successive equal value vertical components.

대표청구항 ▼

[ I claim:] [1.] A method of monitoring in a ball game the position relative to a reference line (20, 28) extending linearly between near and far ends thereof, of the first contact of a game ball (12) with a playing surface (10) carrying said reference line (20, 28), which method includes the follow

[ I claim:] [1.] A method of monitoring in a ball game the position relative to a reference line (20, 28) extending linearly between near and far ends thereof, of the first contact of a game ball (12) with a playing surface (10) carrying said reference line (20, 28), which method includes the following steps:(a) from said near end of the reference line (20, 28), directing a single homogeneous collimated radiation beam (42) of substantially parallel separate rays of radiation along said reference line (20, 28) so as to irradiate a predetermined field (44) at said far end of the reference line (20, 28) lying adjacent the reference line (20, 28), said radiation beam (42) having a transverse cross section such as will be materially but not wholly interrupted by the passage of the game ball (12) through the beam (42) when in play near said reference line (20, 28);(b) at the far end of the reference line (20, 28), receiving at closely spaced locations (46) in said field (44) respective separate spaced rays of said radiation beam (42), which locations (46) are disposed in a column and row, or similar formation;(c) converting the respective received separate rays of beam radiation into corresponding electrical signals;(d) storing the respective electrical signals in respective signal storage elements (60) of a storage means (58) for retention therein until reset by the passage of the game ball (12) through the radiation beam (42), each said storage element (60) when storing a said electrical signal representing a ray of said radiation beam (42) which is not interrupted by the game ball (12), and each said storage element when not so storing a said electrical signal representing a ray of said radiation beam (42) which is interrupted by the game ball (12);(e) deriving from said storage means (60) a representation of the path (14, 16) of an upper or a lower peripheral part of the game ball (12) as the game ball (12) impacts and bounces on the playing surface (10) at or near the reference line (20, 28) whilst passing through the radiation beam (42);(f) observing changes in the declination of that path (14, 16); and(g) deriving from the changes in declination of that path (14, 16) the position of first contact of the game ball (12) with the playing surface (10).