| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball point pen wherein a clearance between a valve body and a valve chamber is appropriate, action of the valve body is smooth and writing is smooth by developing a structure of the ball point pen wherein a projection of the valve chamber is eliminated, an undercut part of the valve chamber is solved, and when a pen point tip is directed downward, a rear end opening of the pen point tip is not blocked with the valve body. SOLUTION: A shape of an opening 15 of a rear end part of a pen point tip S is square. When the ball point pen is postured in the pen point tip 5 directed upward, a valve body 8 abuts liquid tightly against a valve seat 25, and ink is prevented from back flow. When the pen point tip 5 has a posture of facing downward, though the valve body 8 abuts aginst the opening 15 of the rear part of the pen point tip 5, since the rear end part opening 15 of the pen point tip 5 is square, a shperical surface of the valve body 8 does not conform to the rear end opening 15, and a vacant space 16 is generated at a corner part of the opening 15. The ink flows into the pen point tip 5 side via the vacant space 16, and supplied to a writing ball 10. |
