Ballpoint pen

Patent metadata

Field	Value
Publication number	US-9533528-B2
Application number	US-201414476960-A
Country	US
Kind code	B2
Filing date	Sep 4, 2014
Priority date	Sep 6, 2013
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

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.

First claim

The invention claimed is:

1. 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.

2. The ballpoint pen according to claim 1 , wherein the inorganic particles are selected, at least, from carbon black, alumina, boron nitride or titanium oxide.

3. The ballpoint pen according to claim 1 , wherein convex parts derived from alumina are not observed on a surface of the writing ball when writing is finished.

4. The ballpoint pen according to claim 1 , wherein the holder has a ball receiving seat provided on a bottom of the ball house and formed around the ink guiding hole, a plurality of ink grooves arranged equidistantly around the ink guiding hole so as to connect the ball receiving seat and the ink guiding hole.

5. The ballpoint pen according to claim 1 , wherein said content of said aluminum element is 0.06 weight % or less.

Assignees

• Mitsubishi Pencil Co

Inventors

• Osano yoshihisa
• Ishii Yoshihide
• Ooyama Misao
• Hanatani Saki

Classifications

• B43K1/084

  Ball beds · CPC title

• B43K1/082 Primary

  Balls · CPC title

• B43K7/08

  Preventing leakage · CPC title

• B43K7/00

  Ball-point pens ({B43M11/085 takes precedence}; multiple-point writing implements B43K27/00) · CPC title

• B43K7/105

  Feed bars · CPC title