| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball point pen tip which ejects the proper discharge of ink from the end of the tip. SOLUTION: In a ball point pen tip, by a tip end fringe part 8 bent inward and a ball seat 9, a ball is held freely rotatably in a ball holding chamber 3 with a part projected from the tip end part 8. The diameter of an ink passage hole 5 is made 45-65% of the diameter of a ball 2. The volume of the ink bank part of a gap part excluding a radial groove extending radially from the ink passage hole which is formed by the ball 2 in the section of a ball seat from the central diameter part of the ball 2 and the side wall of a ball holding chamber 7 is made 3.0-12.0% of the volume of the ball. |
