| 摘要 |
<p>In order to make an arm supporting base small, to enable the arm supporting base to move horizontally and rotatably, to prevent an occurrence of a fatigue of the arm operating a mouse for personal computer and to enhance the efficiency of work, a plurality of ball bearings are interposed between a movable base and a fixed base in such a manner as the movable base is prevented from being removed from the fixed base and the movable base may move in all directions relatively to the fixed base in a certain range. <IMAGE></p> |
