Patent ID: 7140799

Claim:
A writing implement comprising: an ink storage part storing ink, a writing tip applying the ink, an ink guiding hole connecting said ink storage part and said writing tip, and a reverse flow prevention mechanism provided in a midway of said ink guiding hole and preventing reverse flow of the ink; said reverse flow prevention mechanism comprising: a valve chamber consisting of a part of said ink guiding hole, an inflow port opened to the ink storage part side of said valve chamber and having a smaller inner diameter than that of the valve chamber, an outflow port opened to the writing tip side of said valve chamber and having a smaller inner diameter than that of the valve chamber, a valve element stored in said valve chamber and being movable in the valve chamber by its own weight, a restricting body being stored in said valve chamber at a position on the outflow port side of said valve element, being formed not to touch said writing tip, and being formed in a shape not to interrupt an ink flow in the valve chamber and not to close said outflow port, and being movable in said valve chamber by its own weight, and a valve seat provided around said inflow port; said inflow port being closed by said valve element falling toward the inflow port by its own weight to touch said valve seat when said writing tip is faced upward; said inflow port being opened by said valve element falling toward said outflow port by its own weight to depart from said valve seat and touching said restricting body not to reach the outflow port when said writing tip is faced downward.