Patent ID: 8162554
Filing Date: 2012-04-24
Classification: B43K

Abstract:
1. A writing implement including a knock mechanism capable of advancing a writing tip by push-out operation, comprising: a holding section for holding the writing tip; a shaft tube for containing the holding section; a knock section for covering a rear end portion of the shaft tube; a push-out section for pressing the holding section toward a front end in operative association with push-out operation of the knock section; and a damper space being provided between the knock section and the shaft tube and sealed off from the outside; volume of the damper space being reduced by the push-out operation of the knock section, wherein: the rear end portion of the shaft tube is formed as a reduced-diameter portion having a reduced outer diameter; the knock section is shaped to cover the rear end portion of the shaft tube; a front half portion of an inner space of the knock section is formed as a large-diameter portion having a larger inner diameter; a rear half portion of the inner space of the knock section is formed as a small-diameter portion having a smaller inner diameter; the push-out section is protruded from a rear end surface of the small-diameter portion of the knock section; the push-out section passes through the reduced-diameter portion to abut against the holding section; the inner diameter of the large-diameter portion is formed to be slightly larger than an outer diameter of a base portion which consists a front side portion of the shaft tube before the reduced-diameter portion; the inner diameter of the small-diameter portion is formed to be slightly larger than the outer diameter of the reduced-diameter portion of the shaft tube and smaller than the outer diameter of the base portion, a front-seal member that seals a clearance between the base portion and the large-diameter portion is mounted to an outer periphery of the base portion, a rear-seal member that seals a clearance between the reduced-diameter portion and the small-diameter portion is mounted to an outer periphery of the reduced-diameter portion, and a clearance between the large-diameter portion and the reduced-diameter portion is cut off from the outside by the front-seal member and the rear-seal member to form the damper space.