| 摘要 |
A writing instrument is provided with a retractable writing tip (25) moving between a first retracted position (9) and a second extended writing position (6). The writing instrument may be a retractable pen or a pencil. The writing tip (25) is extended for writing, or retracted when not in use, by moving a track follower (1,46) along a track (4). The track is shaped as a closed loop. The writing instrument preferably includes a hollow barrel (12) and a piston (9) connected to the barrel. The writing tip is provided on a writing cartridge housed within the hollow barrel. The piston is activated to move the follower along the track and to move the writing tip between the retracted and extended positions. The track may be a heart-shaped recess located on a surface of one of the piston or pen barrel. The track follower is located on the other one of the piston and pen barrel. Preferably, the track has four returns to guide the follower in a desired direction along the track. |
