| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a ball for ball-point pen which makes it hard for the line drawn on the paper to be discontinuous and makes it hard for ink balls to occur, and to provide a writing utensil using this. <P>SOLUTION: The ball for ball-point pen 6 made of ceramics, includes a plurality of openings whose Haywood diameter at maximum is 78 μm or less on the surface thereof, variable coefficients V<SP>1/2</SP>/X of some of the openings whose equivalent circle max diameters exceed 2 μm satisfying the following formula; 0.95≤V<SP>1/2</SP>/X≤1.75. (Where V<SP>1/2</SP>/X is the standard deviation of the equivalent circle diameter; X is the average value of the equivalent circle diameter). <P>COPYRIGHT: (C)2010,JPO&INPIT |
