Pen tip structure

Details Pen tip structure Pen tip structure

1986-01-24

1989-01-03

Apley, Richard J.

Coating implements with material supply

Including ball, roller or endless-belt tool

Ball

401216, 401284, B43K 710

Patent

active

047952865

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a pen tip structure characterized in that a ball retaining portion thereof and an ink flow space conducting the ink to the ball retaining portion can be simply structured just by assembling two members into one unit, resistance to rotation of the ball within the ball retaining portion during the writing operation is low, and, while the ink is transmitted by capillary action from the ink flow space to ink flow paths on the end surface portion of a ball receiving stem, i.e., into the ball retaining portion, extraction of the ink by the ball is smoothly carried out within this ball retaining portion, and provides good productivity in the manufacture and proper functioning in writing, suited for various applications such as for writing, drawing, and toilet purposes, and chiefly made of the same kind of metallic material.


BACKGROUND ART

Ballpoint pens are well known as writing instruments and utilize a ball in the pen tip portion which rotates due to frictional force created in the writing motion to deposit ink on the writing surface. The pen tip structure of the ballpoint pen comprises a ball retaining shaft and a ball rotatably received in the ball retaining portion of the ball retaining shaft. The bottom of the ball retaining portion of the ball retaining shaft is formed into a cone-shape and an ink flow hole is bored in the center of the cone-shaped bottom.
There are problems in connection with the manufacture and writing performance and electrostatic action a ballpoint pens as follows.


PROBLEMS IN MANUFACTURE

When the ball retaining shaft is made of metal, the ball retaining portion and the ink flow hole are manufactured by machining or forming, thus requiring high precision machining. When the ball retaining shaft is made of plastic, high precision forming dies are required.


PROBLEMS IN WRITING

Due to the fact that the bottom of the ball retaining portion for operably holding the ball for rotation under writing pressure is cone-shaped, such that the ball receives resistance to its rotation by wedging action, the ball is hindered from rotating smoothly and the extraction of the ink by the ball becomes unsteady. As a result, intermittence in the written line occurs, which means that such a ballpoint pen is not suitable for speed writing.


PROBLEMS DUE TO ELECTROSTATIC ACTION

When the pen tip is formed of a combination of different metals, e.g., when the ball retaining shaft is made of brass and the ball is made of a hard steel, corrosion due to the potential difference between the metals produces rust and the rust clogs the ink flow path, preventing smooth flow of the ink.
Accordingly, the present invention has as its primary object the provision of a pen tip structure which is free from the above stated problems encountered in the prior art, which is easy to manufacture, which allows the ball to rotate and extract the ink smoothly, and which is suited for speed writing.
Another object of the invention is the provision of a pen tip structure in which the ink flow path is formed of a plurality of paths communicating with each other at the center of the end surface portion of the ball receiving stem, whereby the entire region the ink is conducted thereinto on the bottom of the ball retaining portion including the portion with which the ball rubs is improved.
A further object of the invention is the provision of a pen tip structure in which the ink flow path is disposed from an end of the ink flow space to the center of the end surface portion of the ball receiving stem, whereby the region the ink is conducted thereinto at the bottom of the ball retaining portion with which the ball rubs is improved.
Still another object of the invention is the provision of a pen tip structure in which the ink flow path is disposed from an end of the ink flow space to the vicinity of the ball receiving surface portion in the center of the end surface portion of the ball receiving stem, whereby the strength of the ball receiving portion against which the ball rubs is

REFERENCES:
patent: 566558 (1896-08-01), Bell
patent: 2551490 (1951-05-01), Ferst et al.
patent: 3537801 (1970-11-01), Corte
patent: 3781123 (1973-12-01), Linz et al.
patent: 3904297 (1975-09-01), Hori
patent: 4384800 (1983-05-01), Dyama
patent: 4529329 (1985-07-01), Hirabayashi et al.

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