Patent ID: 8714856

Claim:
A ballpoint pen tip comprising a writing ball for transferring ink attached to a surface thereof to a writing object and a holder having this writing ball rotatably provided at a tip; the holder being provided with: a ball housing formed as a housing space for rotatably housing the writing ball, a back hole extending from the rear end of the holder to the vicinity of the ball housing, and an ink guide hole having a section arcuately curved towards an outer edge and allowing the ball housing and the back hole to communicate with each other; a recess gradually tapered toward the ink guide hole being formed in the bottom of the ball housing; the recess being provided with: a plurality of inclined surfaces inclined in such a way that normals of the plurality of inclined surfaces pointing out of a volume point towards a center axis of the pen, and a plurality of troughs formed in parts where these inclined surfaces intersect and extending radially from the ink guide hole to serve as channels communicating the ink guide hole and a frontal part of the writing ball; each of the inclined surfaces being formed with a ball receiving seat surface composed of a concave surface corresponding to the spherical surface of the writing ball to receive the writing ball; and each of the ball receiving seat surfaces being formed inclined in such a way that normals of the ball receiving seat surfaces pointing out of the volume point towards the center axis of the pen, with an arcuately curved peripheral edge.