Patent ID: 7862249
Filing Date: 2011-01-04
Classification: B43K

Abstract:
1. A ballpoint pen tip comprising: a holder; a first tapered surface formed by tapering an outer periphery at a front end of the holder; a connecting surface being a surface formed at a front end side of the first tapered surface, and making an outside angle larger than 180° with respect to the first tapered surface in a virtual section including an axis of the holder; a second tapered surface being a tapered surface formed at a front end side of the connecting surface, and making an outside angle smaller than 180° with respect to the connecting surface in the virtual section; a ball house formed as an inner space of the first tapered surface, the connecting surface, and the second tapered surface; a back hole formed as an inner space extending from a rear end of the holder to a vicinity of the ball house; an ink hole being a hole with a circular section penetrating between the ball house and the back hole; channel grooves being a plurality of grooves provided at regular intervals around the ink hole so as to communicate between a bottom surface of the ball house and the ink hole; a writing ball located in the ball house; a ball seat formed in the bottom surface of the ball house by transferring a part of a curved surface of the writing ball; and a bent portion being formed by inwardly bending a front end portion of the second tapered surface; a boundary between the first tapered surface and the connecting surface being referred to as a first shoulder portion; a boundary between the second tapered surface and the bent portion being referred to as a second shoulder portion; and the second shoulder portion being located inside an virtual tangent line between the first shoulder portion and the writing ball in the virtual section.