| 摘要 |
PROBLEM TO BE SOLVED: To provide a retractable ball point pen capable of preventing a ball from falling due to a shock from dropping or knocking and keeping a stable amount of ink outflow.SOLUTION: A retractable ball point pen includes a friction body having rubber-like elasticity at a rear end part of a shaft tube, the friction body being capable of rubbing handwriting of thermochromic ink and thermally changing a color of the handwriting of the thermochromic ink with frictional heat caused from rubbing. A coil spring is arranged behind a ball, the coil spring pressing the ball against an inner wall at a pen tip with a pressing force higher than a total weight of the retractable ball point pen. A clearance of the ball in a longitudinal direction is 30 to 40 μm, and an outer diameter of a caulking part is 1.0 to 1.2 times a diameter of the ball. The retractable ball point pen with a pen tip ejected has a center of gravity at an intermediate part thereof or a rear side of the intermediate part. |
