Ballpoint pen refill and fabrication method thereof

Details Ballpoint pen refill and fabrication method thereof Ballpoint pen refill and fabrication method thereof

1997-08-18

1999-11-16

Recla, Henry J.

Coating implements with material supply

Including ball, roller or endless-belt tool

Ball

401209, 401212, 401216, 401217, 401219, B43K 710

Patent

active

059845597

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a ballpoint pen refill that uses an ink which is accommodated within an ink-accommodating tube and which has a viscosity that reduces with shear (a thixotropic property) such that the viscosity thereof is high in a static state but drops when a ball rolls. More particularly, it relates to a ballpoint pen refill in which drying out or leakage of the ink from an end portion of the tip is prevented by a configuration in which a coil spring is disposed within a front end aperture of the ink-accommodating (ink) tube and presses against a ball, either directly or via a movable member, within an inner reshaped surface of a front end rim that holds the ball of the ballpoint pen tip.


BACKGROUND ART

A capped ballpoint pen of the prior-art shown in FIG. 7 uses an ink which is endowed with a thixotropic property and which is poured directly into an ink-accommodating tube 1. The ink 2 that is endowed with a thixotropic property, such that the viscosity thereof is high in a static state but drops when the ball rotates during writing, is accommodated within the ink-accommodating tube. An ink follower 3 that follows the consumption of the ink and also prevents the ink from flowing backwards, is inserted at a rear portion of this ink. An engagement portion 9d of a tip holder member 9 is fitted in the front end of the ink-accommodating tube, and a ballpoint pen tip 4 is fitted in a front end aperture 9a thereof. A stopper 5 provided with a ventilation means is fitted in the rear end of the ink-accommodating tube 1. This type of ballpoint pen refill is inserted into a penholder tube B in a state such that only a writing portion protrudes from the front end thereof, and a front end portion of this penholder tube is covered by a cap C.
The prior-art ink-accommodating tube 1, shown in FIG. 8, has a smaller-diameter portion 1c that is open at the front end and a larger-diameter portion 1d that is open at the rear end. The ink 2 endowed with a thixotropic property and the ink follower 3 at the rear of this ink are incorporated within the ink-accommodating tube 1. The ballpoint pen tip 4 is fitted into a front end aperture 1a of the ink-accommodating tube 1, and a coil spring 7 that always presses a ball 6 against an inner reshaped surface 4f of a front end rim portion 4b that holds the ball is also disposed therein. The stopper 5 provided with a ventilation means (such as an opening) is fitted into the rear end of the ink-accommodating tube 1. This example relates to a refill which uses an ink having a thixotropic property and which is poured directly into an ink-accommodating tube, whereby drying of the ink at the front end of the tip or leakage thereof is prevented.
In the prior-art, a ballpoint pen or refill that uses a low-viscosity ink (a water-based ink) necessitates a complicated structure. This complicated structure may be similar to that of an internal-wadding type of water-based ballpoint pen wherein ink is guided to a tip end portion by a relay core in which ink is absorbed by an ink-absorbing member of cotton-like fibers covered by an outer film. Another example of a complicated structure may be that of a pen-core type of water-based ballpoint pen that uses a pen core member having an ink-flow adjustment function that comprises comb grooves which pour the ink directly into the ink-accommodating tube, ink grooves, and air grooves. A ballpoint pen or ballpoint pen refill which is formed by the direct pouring of an ink endowed with a thixotropic property, which provides clear handwriting with the same smooth writing feeling as that of a low-viscosity ink, has an advantage in that it is simple to pour the ink directly into the ink-accommodating tube. This feature is obtained because, although the ink maintains a high viscosity in a static state, the viscosity drops at the instant at which a shearing action occurs in the ink in contact with the ball surface when the ball rotates, so that the ink becomes a fluid.
On the other hand, if a state is assumed in which an impact

REFERENCES:
patent: 4973180 (1990-11-01), Hori
patent: 5277510 (1994-01-01), Okamoto et al.
patent: 5678942 (1997-10-01), Kobayashi et al.

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