| 摘要 |
PURPOSE: A stepping motor is provided to stably support an axis of a rotor all the time, thereby preventing a ball from being uncoupled from a lead screw. CONSTITUTION: The ratio of the length of the other end of a lead screw to a pre-pressurization length is larger than 2. The lead screw is supported by a pivot bearing(82). The pre-pressurization length is a length of one end of a rotative axis(11) supported by a pre-pressurization device. The length of the other end of the lead screw is the length of the other end of the lead screw which is inserted into the pivot bearing. The ratio of lengths is in the range of 2.01 to 5. |
