Light pen for personal digital assistant, has joint stopped by edge extending towards interior on height of drum when cylinder passes drum, and push rod pressed in drum to move push cylinder to compress spring during retraction of pen

摘要

The pen has a cap (50) having an upper joint (53) stopped by an edge extending towards interior on a height of a drum (20) when a cylinder (51) passes the drum to drive fixation of inner threads (511) on outer threads (521) of a pushrod (52). The push rod is pressed in the drum to move a push cylinder (42) for compressing a spring (44) during retraction of the pen so that tooth (412) rotates from a groove (431) towards a groove (432) in a clockwise direction. The rotation of the tooth drives a control bar (41) to skip a pitch for completely hiding the pen in a hollow receptacle.