| 摘要 |
<P>PROBLEM TO BE SOLVED: To make it possible to simply and economically form a female thread forming on the internal surface of an outer tube without using motor-driving molds in the ejection device of an eraser or the like utilizing a paired screw. <P>SOLUTION: A rack window (28) is formed by opening windows (27) corresponding to some part of the screw groove of the female thread at the predetermined axial pitch on a flat part (26) provided on the inner peripheral surface of the outer tube (16). In the outer tube (16), a cradle (25) rotating by an inner tube (24) is provided. To the cradle (25), a male thread (44) threaded with the rack window (28)is provided. By rotating the inner tube (24), the cradle (25) is axially shifted by the rack window, resulting in enabling to retract and extend the eraser. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
