Patent ID: 7038764
Filing Date: 2006-05-02
Classification: A63B,G01P

Abstract:
1. An apparatus for determining the velocity of a projectile moving along a trajectory, said apparatus comprising of: a first sensing plane perpendicular to said trajectory comprising a plurality of light emitting devices and a plurality of light sensitive detectors, the light emitting device being position to emit light beams to form a first light curtain in a plane perpendicular to said trajectory, the light sensitive detectors being position to form a first detecting plane perpendicular to said trajectory and parallel to said first light curtain, the said first detecting plane to be position close to the first light curtain so as to be able to detect reflected light from the first light curtain, the said reflected light as caused to be reflected as the projectile passes the first light curtain, the light sensitive detectors having the means for producing a first signal indicative of the entry of the projectile into the first light curtain; a second sensing plane perpendicular to said trajectory comprising a plurality of light emitting devices and a plurality of light sensitive detectors, the light emitting device being position to emit light beams to form a second light curtain in a plane perpendicular to said trajectory, the light sensitive detectors being position to form a second detecting plane perpendicular to said trajectory and parallel to said second light curtain, the said second detecting plane to be position close to the second light curtain so as to be able to detect reflected light from the second light curtain, the said reflected light as caused to be reflected as the projectile passes the second light curtain, the light sensitive detectors having the mean for producing a second signal indicative of the entry of the projectile into the second light curtain, the said second sensing plane being position parallel to said first sensing plane and aligned with said trajectory a distance apart; means responsive to said first and second signal for measuring the interval between the passage of said projectile through said first sensing plane to said second sensing plane for calculating a velocity corresponding to the measured time and the distance between said first and second sensing plane and displaying said calculated speed; an enclosure with a plurality of openings along one planar face, said openings to coincide with said light emitting devices and said light sensitive detectors of said first and said second sensing plane and said light emitting devices and said light sensitive detectors are contained within said enclosure below said openings.