| 摘要 |
PURPOSE: An ink back flow preventing device of a ball point pen improves an ink back flow preventing effect by quickly closing the inlet of an ink by using a heavy ball valve. CONSTITUTION: Only, a pillar type valve(30) is contained in a valve room(12) such that an ink back flow preventing device having the pillar type valve(30) is easily manufactured and assembled. The pillar type valve(30) has a longitudinally concave ink passage(31) formed on the surface thereof, thereby easily extruded at low cost. The pillar type valve(30) is heavier and has wider surface than prior ball valves such that an interfacial tension between the surface of the valve(30) and the inner wall of the valve room(12) is increased.
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