| 摘要 |
PURPOSE:To attain contactless and instantaneous measurement of the spin of a golf ball and to eliminate the influence of noises by attaching a reflective mark on the surface of a golf ball through a detection angle and by detecting the rotation of the marked part of the ball. CONSTITUTION:The reflective mark 1 having a detection angle theta is attached to a golf ball 10. A light projecting surface 4 and a light receiving surface 5 each consisting of optical fibers 3 are disposed directly below the track of the ball. When the leading end of temark 1 come to a bottom position (A) during the spin of the ball, light emitted from a light source 6 and projected through a lens 8, an infrared ray filter 9 and an optical fiber 3 is reflected by the mark. The reflected light is inputted a light receiving element 7 through the optical fiber 3 to provide a signal. The signal is continuously provided until the trailing end of the mark comes to the bottom position (B). The signal is inputted a time detector 14 through an amplifier 13 to measure the duration t of the signal. The spin s=60Xtheta/(tX360)rpm is calculated by an arithmetic unit 15 on the basis of the detection angle theta and the duration t and is displayed on an indicator 16. |
