| 摘要 |
PURPOSE:To simplify, and make a structure small and light by a method wherein a belt is laid on parallel cylindrical nuts respectively having right-handed threads and left-handed threads through another free roller, and is coupled with a moving stage. CONSTITUTION:When lead screws 4, 5 are revolved at uniform velocity in the same direction, driving rollers 8, 9, the nuts, try to move in the axial directions of the lead screws 4, 5, but forces trying to move the nuts are same in the magnitude and act in the direction opposite to each other, because the lead screws 4, 5 are threaded reversely each other with the same pitch. Since, however, the driving rollers 8, 9 are coupled through a belt 12, these forces cancel each other and the driving rollers 8, 9 are not moved in Y-direction, the axial direction. Accordingly, a stage 11 is moved in X-direction. The direction in which the stage 11 moves is changed according to a way of combination of directions in which the lead screws 4, 5 rotate. |
