| 摘要 |
PURPOSE:To freely set a final gear reduction ratio or the like comparatively by setting a reduction ratio between a final output stage gear and its preceding stage gear to one over an integral number. CONSTITUTION:A reduction ratio between a final output stage gear 1e and its preceding stage gear 1d is set to one over an integral number. Moreover, a ratio of number of teeth of other gears 1a, 1b, 1c is not especially set to an integral number ratio. Even when mis-centering error or the like takes place in any of 1st-3rd gears 1a-1c which are intermediate gears, since only the gear reduction ratio of gears after a gear having the eccentricity is effective to a ball screw 3, the error is reduced by the reduction ratio and almost no hindrance is caused to the feeding accuracy of an original. Thus, the final gear reduction ratio of a reduction gear train 1 is comparatively freely set. |
