f) In case the ball does not rotate on paper 2

• The ball pen transfers the ink of the pen to paper by rotating the ball on paper. For that reason it is ideal to write with a writing angle of 60° or more for the ball to rotate.
• The ball does not rotate properly when writing a pen lying down, and the ink does not come out in the place of writing. In some cases, the paper may be scraped off with a pen tip causing jams in the paper, or the parts holding the ball may wear out in the paper and leak ink.

In case multiple colure pen

• For multi-colored ballpoint pen, the refill of each color is installed at a position away from the center of the barrel. Therefore, when the pen tip is extended, the pen tip of each color becomes "slightly oblique" toward the center of the barrel. In the above picture, the yellow broken line shows the center of the barrel, the red broken line shows the center of the pen tip (the side closer to the writing surface). As a result, even with an angle at which writing can be done without problem even with a single-function pen, with "multicolor ballpoint pen" "only the refill on the side close to the writing surface" becomes the further angle, parts that support the ball at the tip of the pen scratch the paper surface, making paper fibers more likely to occur.