| 摘要 |
PROBLEM TO BE SOLVED: To provide a tip for ballpoint pen employing shear-rate thinning viscous ink, in which non-writing or patchy writing due to back shock is prevented and bubbles will not remain in the tip after deaeration treatment. SOLUTION: An ink introducing port 12 is provided with an ink groove 12a having a length, not reaching to an ink passage 13, while a resilient member 20 is constituted of a small diametrical spring unit 21, inserted loosely into the ink introducing port 12 to push a transfer ball 1 through the tip end of the same, and a large diametrical spring unit 22 formed at the rear side of the small diametrical spring unit 21. The small diametrical spring unit 21 is provided with a seat winding unit 21a, in which the coils at the tip end side are adhered to each other, whereby the reverse flow of ink, flowing from the ink groove 12a toward the ink passage 13, is prevented upon the back shock and, further, the invasion of the tip end unit of the resilient member 20 into the ink groove 12a or into a gap between the inner surface of an ink house 11 and the transfer ball 1 can be prohibited. |
