| 摘要 |
PURPOSE:To let an accurate positioning device free of jarring be realized by providing the device with a pre-load means applying pre-load to a feed nut in the specified direction, and making it possible to adjust the aforesaid pre-load to a desired value when a driven section is positioned at a desired position via the feed nut with the feed screw rotated. CONSTITUTION:When a rotating drive section 9 is driven so as to allow its rotation to be transmitted to a feed screw 13 via a speed increase/decrease section 8 and a rotational shaft joint 11, a feed nut 15 engaged with the feed screw 13 is moved to the direction indicated by an arrow head (a), and a driven section 2 connected to the feed nut 15 by a connecting member 14 is moved to the same direction, so that for example, the optical means of an optical disc master exposure means rested over the driven section is moved with high accuracy. In this case, the supply of high pressure from a pressure source 17 which is adjusted to a desired value by a pressure control section 18, permits contact surface pressure between the feed screw 13 and the feed nut 15 to be kept roughly constant. By this constitution, friction torque is restrained from fluctuating, so that accuracy in positioning can thereby be enhanced. |
