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US 6,443,649 B1Granted
Free-ink type writing instrument
AssigneeMitsubishi Pencil Company, Limited
InventorsTakao Koyama, Kazuhisa Kirita, Atsushi Iwasa
Life of this patent
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Abstract
A free-ink type writing instrument includes: an ink tank for holding ink; a temporary ink collector for temporarily retaining the ink flowing out from the ink tank; a partitioning wall separating the ink tank and the temporary ink collector; and a pen core disposed from the ink tank, penetrating through the partitioning wall and the ink collector so as to allow ink to flow out from the ink tank, and is characterized in that the storage volume Vc of the ink collector and the ink tank volume Vo satisfy the relation Vc≧0.18 Vo.
Claims1
A free-ink type writing instrument comprising:
- an ink tank for holding ink;
- a temporary ink collector for temporarily retaining the ink flowing out from the ink tank;
- a partitioning wall separating the ink tank and the temporary ink collector;
- and
- a pen core disposed from the ink tank, penetrating through the partitioning wall and the ink collector so as to allow ink to flow out from the ink tank,
- characterized in that the ink stored in the ink tank has a vapor pressure ranging from 20 mmHg to 60 mmHg at a temperature of 25° C. and a surface tension of less than 30 mN/m at a temperature of 25° C., and the storage volume Vc of the ink collector and the ink tank volume Vo satisfy the relation Vc≧0.18 Vo.
3 more elements
Dependencies are inferred from the claim text.