Ball-point pen
AssigneeMitsubishi Pencil Company, Limited
InventorKazuhiko Furukawa
Life of this patent
Estimating the term…
Abstract
A ball-point pen having a point assembly, in which the inside and outside diameters of a press formed portion (3) for preventing a ball (1) from slipping out, a sealing face (8), the projected amount of the ball, the diameter of a ball seat (16), the longitudinal backlash and the like are formed in optimized dimensions, sealing face (8) is configured so as to have a radius of curvature approximately equal to that of ball (1), and ball seat (16) having a radius of curvature approximately equal to that of ball (1) is formed in the rear of ball (1), while a multiple number of channels (4) for leading ink (13) to the pen point are provided inside the point assembly.
Claims20
A ball-point pen comprising:
- ink reservoir tube which stores an ink therein;
- point assembly which is disposed in the front of the ink reservoir tube and holds a ball to be a writing point at the front end thereof by means of a press formed portion at the front end of the holder so that the ball is rotatably projected from the front part thereof and is prevented from slipping out;
- and aqueous ink, characterized by meeting all the following requirements 1) to 3):
- 1) the writing ball diameter .phi.A, the diameter .phi.J of the ink hole constituting interior ink passage, the ball seat angle P and the ball seat diameter .phi.K satisfy the following relations:
- 100.degree.<P<150.degree.
- .phi.A.times.0.40<.phi.J<.phi.A.times.0.80
- .phi.A.times.0.50<.phi.K<.phi.A.times.0.90
- 2) three or more channel grooves constituting an ink passage during writing, are provided in the rear, with respect to the axial direction, of the ball, the channel grooves being terminated partway not penetrating rearward to the ink reservoir tube, and the circumscribed circle diameter .phi.Q of the channels, the finished diameter .phi.S, with respect to transversal direction, of the side wall for limiting the loosely held ball, the ball projected amount H when the ball is put in close contact with the ball seat and the ball seat diameter .phi.K satisfy the following relations:
- .phi.A.times.0.95<.phi.Q<.phi.A.times.1.05
- .phi.A.times.1.02<.phi.S<.phi.A.times.1.10
- H.times.2.3<.phi.K
- 3) the loosely held ball can move in the axial direction with a longitudinal backlash M falling within the range:
- .phi.A.times.0.01<M<.phi.A.times.0.10.
A ball-point pen comprising:
- ink reservoir tube which stores an ink therein;
- and
- point assembly which is disposed in the front of the ink reservoir tube and holds a ball to be a writing point at the front end thereof by means of a press formed portion at the front end of the holder so that the ball is rotatably projected from the front part thereof and is prevented from slipping out, characterized by meeting all the following requirements 1) to 3):
- 1) the angle B of the tapered press formed portion, the writing ball diameter .phi.A, the outside diameter F of the press formed portion, the inside diameter .phi.G of the press formed portion and the projected amount H of the ball satisfy the following relations:
- 60.degree.<B<100.degree.
- .phi.A.times.0.90<.phi.F<.phi.A.times.1.10
- .phi.A.times.0.90<.phi.G<.phi.A.times.0.98
- .phi.A.times.0.20<H<.phi.A.times.0.40
- 2) the inside diametric portion has a circumferential sealing face having a width I and a radius of curvature approximately equal to the radius of the writing ball, I falling in the following range:
- .phi.A.times.0.01<I<.phi.A.times.0.15
- 3) the loosely held ball can move in the axial direction with a longitudinal backlash M falling within the range:
- .phi.A.times.0.01<M<.phi.A.times.0.10.
Dependencies are inferred from the claim text.