Ball point pen

Details Ball point pen Ball point pen

2003-10-22

2004-10-19

Huson, Gregory L. (Department: 3751)

Coating implements with material supply

Including ball, roller or endless-belt tool

Ball

C401S142000

Reexamination Certificate

active

06805511

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a ball point pen having low-viscosity ink directly reserved in an ink tube, and an ink follower disposed at a rear end of the ink.
In the conventional art, as disclosed in JP-Y2-2555677 (Japanese Registered Utility Model Publication Number: 2555677), a ball point pen has a paste-like backflow preventing agent disposed in an ink tube charged with ink in front of the backflow preventing agent, a tip fixed to a front end of the ink tube while rotatably holding a ball partially protruding from a front end of the tip, and a spring for urging the ball to come into contact with an inward front end edge of the tip when the ball point pen is not used. Further, low-viscosity aqueous ink is charged in the ink tube.
In the conventional-art ball point pen, low-viscosity aqueous ink is charged. Accordingly, abundant ink outflow characteristic can be satisfied when writing starts. There is however the possibility that scratchiness may occur in writing at an early stage after the start of writing because ink outflow characteristic has a tendency to decrease gradually as the head of ink (i.e., water head pressure of ink applied on the pen point) decreases gradually after the start of writing.
To eliminate the scratchiness in writing, it may be conceived that the gap between the inner surface of the front end edge portion and the ball is formed largely in advance. In this case, there is however the possibility that blur may occur in writing because the outflow of ink is too much after the start of writing.
SUMMARY OF THE INVENTION
The present invention is developed to solve the problem in the conventional art and an object of the invention is to provide a ball point pen in which there is no possibility of occurrence of scratchiness and blur in writing until almost consumption of charged ink after the start of writing, even though low-viscosity ink is charged in the ball point pen.
The inventor has made eager examination to solve the problem. As a result, it has been found that occurrence of scratchiness and blur in writing can be suppressed when an outflow of ink (i.e., the amount of consumed ink) until almost consumption of charged ink after the start of writing is specified. The inventor has further paid attention to the fact that the decrement of the head of ink and the increase of the gap between the inner surface of the front end edge portion and the ball (i.e., abrasion of the ball seat) are intimately related to the outflow of ink. As a result, it has been found that the outflow of ink until almost consumption of charged ink after the start of writing can be kept in a proper range to suppress occurrence of scratchiness and blur in writing when the decrement of the head of ink and the increase of the gap between the inner surface of the front end edge portion and the ball are specified.
(1) That is, according to a first aspect, the invention provides a ball point pen
1
including: a tip body
2
including a front end edge portion
21
and a ball seat
22
provided inward at a front end, and a ball
3
rotatably held in the front end edge portion
21
and the ball seat
22
; an ink tube
6
formed so that the tip body
2
is provided at a front end of the ink tube
6
; ink
7
reserved in the ink tube
6
; an ink follower
8
disposed at a rear end of the ink
7
and advancing with consumption of the ink
7
; and an elastic member
4
for urging the ball
3
forward to bring the ball
3
into close contact with an inner surface of the front end edge portion
21
of the tip body
2
, wherein the value of outflow of ink per writing distance of 100 m until a measurement time just before outflow of 80% of the amount of charged ink from the start of writing in the case where an outflow of ink is measured at intervals of a writing distance of 100 m is selected to be in a range between a value smaller by 20 mg than the outflow of ink in the writing distance range of from 0 m to 100 m and a value larger by 20 mg than the outflow of ink in the writing distance range of from 0 m to 100 m.
According to the first aspect, the outflow of ink until almost consumption of charged ink after the start of writing can be kept in a proper range to thereby suppress occurrence of scratchiness and blur in writing.
If the outflow of ink per writing distance of 100 m is smaller than a value smaller by 20 mg than the outflow of ink in the writing distance range of from 0 m to 100 m, there is the possibility that scratchiness may occur in writing because the outflow of ink decreases remarkably compared with that at the time of the start of writing. On the contrary, if the outflow of ink per writing distance of 100 m is larger than a value larger by 20 mg than the outflow of ink in the writing distance range of from 0 m to 100 m, there is the possibility that blur may occur in writing because the outflow of ink increases remarkably compared with that at the time of the start of writing.
The phrase “a measurement time just before outflow of 80% of the amount of charged ink from the start of writing in the case where an outflow of ink is measured at intervals of a writing distance of 100 m” is used for specifying the writing distance in the case where almost of charged ink is consumed.
The writing distance range in the case where almost of charged ink is consumed may be more preferably set “a measurement time just after outflow of 80% of the amount of charged ink from the start of writing in the case where an outflow of ink is measured at intervals of a writing distance of 100 m” in order to elongate the writing-enabled distance in which the outflow of ink can be kept in a proper range.
(2) Preferably, in a second aspect, in addition to the first aspect, in the ball point pen according to the invention, the decrement &Dgr;H of the head of ink per writing distance of 100 m until a measurement time just before outflow of 80% of the amount of charged ink from the start of writing in the case where an outflow of ink is measured at intervals of a writing distance of 100m is selected to be in a range of from 3 mm to 12 mm.
According to the second aspect, occurrence of scratchiness and blur in writing can be surely prevented until almost of charged ink is consumed after the start of writing.
If the decrement &Dgr;H of the ink head per writing distance of 100 m is smaller than 3 mm, there is the possibility that scratchiness may occur in writing easily because the outflow of ink from the front end of the tip body
2
is too little. On the contrary, if the decrement &Dgr;H of the ink head per writing distance of 100 m is larger than 12 mm, there is the possibility that blur may occur in writing easily because the outflow of ink from the front end of the tip body
2
is too much.
The phrase “the decrement &Dgr;H of the ink head per writing distance of 100 m” means an average of descending speed of the ink head due to writing in a time range of from the start of writing to a measurement time just before consumption of 80% of the amount of charged ink in the case where an outflow of ink is measured at intervals of a writing distance of 100 m. The term “ink head” used herein means a height (mm) of the rear end of ink from the pen point when the ball point pen is placed with the pen point down.
(3) Preferably, in a third aspect, in addition to the second aspect, in the ball point pen
1
according to the invention, the increment &Dgr;C of longitudinal movable length C of the ball
3
at a front end of the tip body
2
per writing distance of 100 m until a measurement time just before outflow of 80% of the amount of charged ink from the start of writing in the case where an outflow of ink is measured at intervals of a writing distance of 100 m is selected to be in a range of from 0.1 &mgr;m (0.0001 mm) to 1.5 &mgr;m (0.0015 mm) (more preferably in a range of from 0.1 &mgr;m to 1.0 &mgr;m, further preferably in a range of from 0.1 &mgr;m to 0.5 &mgr;m).
According to (3), the outflow of ink can be more surely set in a proper range until almost of charged ink is consumed after

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