Writing instrument having automatic sealing structure

Abstract

A writing instrument having an automatic sealing structure, in which a hinge part of a holder has projection jaws formed thereon having a role of a stopper that can prevent a hinge shaft from being excessively pivoted, thereby more effectively preventing ink from drying out due to complete sealing of the nib. The writing instrument having an automatic sealing structure, including: a body case having a front opening formed in one end thereof; a knock part coupled to the other end of the body case so as to make a nib protrude from or be retracted into the front opening of the body case by a pushing operation thereof; a cartridge inserted into the body case together with a spring in a state in which the knock part and the nib are coupled to both ends thereof, respectively; at least one O-ring fixedly fitted in the body case; a holder fixedly fitted in the body case so that one end thereof is covered by the O-ring; and a ball shutter pivotally coupled to the holder to allow the nib to protrude or be sealed according to the pivoting thereof, wherein the ball shutter includes hinge shafts formed in a fan shape, and hinge parts of the holder, in which the hinge shaft is pivotally positioned, have projection jaws formed thereon by protruding inwardly to limit a pivot range of the hinge shaft.