| 摘要 |
<p>A machine which can be used by a player practising a ball game such as tennis or badminton has an ejection mechanism comprising a pair of revolving discs (1a, 1b) spaced apart by a gap (2) through which can be drawn a ball (4) for ejection in a direction (3) which can be determined by appropriate adjustment of the vertical and horizontal positioning of the revolving discs by means of inclination drive (10) and sweep gear (12). Side spin or slice can be imparted to the ball by rotation of the revolving discs about an axis lying in the direction (3) of the ball ejection, whilst top spin or under spin can be imparted to the ball by varying the angular velocity of the discs (1a, 1b) by causing them to rotate at differing speeds. The ejection mechanism may be mounted on a height adjusting mechanism in order to vary the height at which the ball is ejected. The machine can be controlled by a microprocessor-based system which may be pre-programmed or operated by remote control.</p> |
