Ballpoint pen
AssigneeMitsubishi Pencil Company, Limited
InventorsYoshihisa Osano, Yoshihide Ishii, Misao Ooyama, Saki Hanatani
Life of this patent
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Abstract
A ballpoint pen 10 includes: a ballpoint pen tip 20 having a writing ball 30 and a holder 21 holding the writing ball 30; a shaft tube 12 to which the rear end part of the ballpoint pen tip 20 is mounted; and ink 40 accommodated in the shaft tube 12. The holder 21 has an ink guiding hole 26 formed from the rear end thereof toward the head end thereof and a ball house 22 formed with the inner circumference near the head end of the holder 21 expanded. The writing ball 30 is formed of a zirconia sintered body with the content of an aluminum element being less than 0.1 weight %, and the ink 40 contains inorganic particles 41.
Claims5
A ballpoint pen, comprising:
- a ballpoint pen tip having a writing ball and a holder holding the writing ball;
- a shaft tube to which a rear end part of the ballpoint pen tip is mounted;
- and
- ink accommodated in the shaft tube,
- the holder having:
- an ink guiding hole formed from a rear end of the holder toward a head end of the holder;
- and
- a ball house formed with an inner circumference near a head end of the holder expanded,
- the writing ball being formed of a zirconia sintered body with a content of an aluminum element being less than 0.1 weight %, and
- the ink containing inorganic particles,
- wherein at least some of said inorganic particles of said ink have a Vickers hardness that is larger than the Vickers hardness of the zirconia sintered body of said writing ball, and
- wherein dark color regions derived from alumina are not observed when a surface or a cross section of the writing ball is observed with a scanning electron microscope.
Dependencies are inferred from the claim text.