| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that a mechanical pencil mechanism bites (breaks) a lead by the shock when the mechanism is accommodated in a shaft.SOLUTION: In a writing utensil, a mechanical pencil unit having a chuck body for holding and releasing a lead and a chuck ring which surrounds a front portion of the chuck body and opens/closes the chuck body is arranged retractable in a shaft cylinder. An outer circumferential part corresponding to a lead holding part of the chuck body includes at least a horizontal portion substantially parallel to the axis and an inclined portion which is located behind the horizontal part and inclined in the axial direction. On the other hand, an inner circumferential part of the chuck ring is formed substantially parallel to the axis. In the writing utensil in which the mechanical pencil unit is retractable, the ratio K/D is ≥14% and <30%, where K denotes the sliding area in which the chuck ring is slidable to the chuck body when the chuck body is attached to the chuck ring to hold the lead, and D denotes the length from a front end of the chuck body to a rear end of the inclined surface. |
