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US 9,375,972 B2Granted
Writing instrument
AssigneeKabushiki Kaisha Pilot Corporation
InventorsHirotaka Masuda, Naoto Masushige
Life of this patent
Estimating the term…
Abstract
A writing instrument includes a pen point retaining member, a pen point that is attached to a first end of the pen point retaining member, an ink tank that is attached to a second end of the pen point retaining member, and an ink that is accommodated in the ink tank. The ink includes a lubricating interface layer-forming compound, and a carbonaceous film is formed on at least one of a surface of the ball or a contact portion of the ball holding portion with the ball.
Claims9
A writing instrument comprising:
- a pen point retaining member;
- a pen point that comprises a ball and a ball holding portion that rotatably holds the ball, and is attached to a first end of the pen point retaining member;
- an ink tank that is releasably attached to a second end of the pen point retaining member;
- and
- an ink that is accommodated in the ink tank and comprises a lubricating interface layer-forming compound,
- wherein a carbonaceous film is formed on at least one of a surface of the ball or a contact portion of the ball holding portion with the ball, the carbonaceous film comprising a carbon atom and an oxygen atom bound to the carbon atom,
- and wherein surface tension of the ink is between 20 mN/m and 40 mN/m in an environment at 20° C.
4 more elements
Dependencies are inferred from the claim text.