Abstract: There is provided a ballpoint pen tip that minimizes thin spots such as impact thin spots even if upward writing or an impact causes entry of air, allows rapid return to normal writing, and minimizes manufacturing costs. A writing ball and a check ball included in the ballpoint pen tip are placed close to each other with a slight clearance therebetween to leave an inner space with a slight capacity. Thus, even if air enters from a caulking portion, the volume of the air stored inside is slight, and an air pool can be rapidly eliminated. Further, both the writing ball and the check ball can be provided in a front end of the ballpoint pen tip, and assembly operations can be easily performed without inverting the ballpoint pen tip.

Abstract: There is provided a ballpoint pen tip that minimizes thin spots such as impact thin spots even if upward writing or an impact causes entry of air, allows rapid return to normal writing, and minimizes manufacturing costs. A writing ball and a check ball included in the ballpoint pen tip are placed close to each other with a slight clearance therebetween to leave an inner space with a slight capacity. Thus, even if air enters from a caulking portion, the volume of the air stored inside is slight, and an air pool can be rapidly eliminated. Further, both the writing ball and the check ball can be provided in a front end of the ballpoint pen tip, and assembly operations can be easily performed without inverting the ballpoint pen tip.

Abstract: A pen cap having at least two engaging portions (59f, 59r) specifically adapted to engage a receiving-side engaging portion (51f) formed on the mouthpiece-side end (7) of a hollow barrel and a receiving-side engaging portion (51r) formed on the tail-plug-side end of the hollow barrel (9), respectively. The engaging portions on the cap are at different locations along the cap's longitudinal axis. Furthermore, the engaging portions on the cap have their engaging surfaces disposed radially outward at different distances relative to the cap's longitudinal axis.

Abstract: A ball-point pen capable of preventing back leakage of ink when the pen is used to write with the ball-point tip above the ink reservoir. The pen has a ball-point tip (15); an ink reservoir (17) and a joint (19) connecting the ink reservoir with the tip for delivering ink to the tip. The joint has a tip-side bore (37a) and reservoir-side bore (33a) connected by a communicating hole (45), for allowing ink to pass from the reservoir-side bore to the tip-side bore. The communicating hole (45) is composed of a large-diameter portion (45b) and a small-diameter portion (45s) connected to the tip-side bore and the reservoir-side bore, respectively, and is eccentric to both bores. A ball 49 having a greater diameter than the bore diameter of the small-diameter portion is disposed to be freely movably in at least a part of a space formed between the rear end of the tip and the large diameter portion when the tip is fitted into the tip-side bore.

Abstract: This invention provides a metal tip for a ball-point pen, having an ink guide hole (2) formed at the center of the bottom surface of a ball holding portion (1) and radial grooves (3) arranged around the ink guide hole. The ink guide hole has a diameter 30 to 55% the diameter of a ball and a length 1.2 to 2 times the diameter of the ink guide hole. A cleaning tool, used for removing a flash which is formed during formation of the radial grooves (3) by cutting (broaching) and which projects into the ink guide hole (2), is set to have a diameter 70 to 97% the diameter of the ink guide hole, so that only a base portion of the projecting flash is left.

Abstract: A ball-point pen having a coupling, a tip at the distal end of the coupling, and a reservoir tube at the proximal end of the coupling. The tip may held in a tip holder, which, in turn, is coupled to the distal end of the coupling. A valve chamber is formed within the coupling with a ball seat having a guide hole therethrough on the rear portion of the valve chamber and projecting ridges on the front portion of the valve chamber. When the ball-point pen is positioned with its tip upward, a ball valve is brought into contact with the ball seat to close the guide hole and thereby prevent back flow of ink. When the ball-point pen is positioned with its tip downward, the guide hole is opened and the ball valve contacts the rear ends of the projecting ridges, so that ink flows into the tip through the guide hole, the valve chamber, and grooves formed between the ridges. A spring may be interposed in the inner hole of the tip with its proximal end held in place by the coupling.