Ink applicator, ink backflow prevention mechanism of ink...

Coating implements with material supply – Including ball – roller or endless-belt tool – Ball

Reexamination Certificate

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C401S219000

Reexamination Certificate

active

06283662

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an applicator such as a ball-point pen or the like. Particularly, the present invention provides a structure suitable to constitute the applicator like the ball-point pen which contains an aqueous ink of various types or more particularly an aqueous ink of a considerably high viscosity.
The term “aqueous inks” used hereinafter generally denotes “inks each containing water or a water-soluble organic solvent” in comparison with “oily inks”.
BACKGROUND OF THE INVENTION
Typically, the conventional ball-point pens have oily inks filled therein. However, some novel types of ball-point pens containing aqueous inks instead of the oily inks have recently developed, wherein the aqueous inks are less viscous than the oily inks. The flow rate of the aqueous inks effluent from such novel type ball-point pens is high enough to ensure the drawing of thicker lines, but these pens are likely to cause the problem of “scratchy lines or blurred strokes”.
This problem results from the fact that a ball-retaining cavity in each of those novel type ball-point pens can not necessarily hold therein a sufficient amount of an aqueous ink less viscous than the oily inks. If the novel type ball-point pens are left for a while to take their upside down position where penpoint tips face upwards, then a considerable amount of the ink will flow down into an ink reservoir from the ball-retaining cavity. Therefore, the ball-retaining cavity will become almost empty to render scratchy or blurred the first strokes or lines.
Some improvements proposed to incorporate check valves to resolve the problem of such a backflow of the ink are disclosed in:
Japanese Patent Publication No. Sho. 28-717,
Japanese Utility Model Publication No. Sho. 54-15703, ibid. 54-15704,
Japanese Utility Model Laying-Open Gazette No. Sho. 62-30684,
Japanese Utility Model Publication No. Hei. 4-52067,
Japanese Utility Model Laying-Open Gazette No. Hei. 6-64956, and ibid. 6-83376.
The Japanese Utility Model Publication No. Hei. 4-52067 is regarded as the most typical one, and the structure of ball-point pen disclosed therein will be discussed below.
FIGS.
25
(
a
) and
25
(
b
) are cross-sectional views of the ball-point pen shown in this publication and comprising a built-in valve.
A ball-point pen
100
shown in the publication 4-52067 comprises a pen-handle
101
and an ink core
102
inserted therein. The ink core
102
consists of a penpoint tip (a.k.a. ‘nib’)
105
, an ink reservoir
106
, a connector
107
and a valve body
108
. The penpoint tip
105
has a writing ball
109
installed therein. The ink reservoir
106
is a cylindrical member to hold therein an aqueous ink. The connector
107
connects the penpoint tip
105
to the ink reservoir
106
and has a bore
110
communicating therewith. A valve seat
111
and lugs
113
are formed in and integral with the bore
110
.
The penpoint tip
105
is fitted in a distal end of the connector
107
, with the ink reservoir
106
being fitted thereon.
The prior art ball-point pen
100
has a valve chamber
115
defined between the valve seat
111
and the lugs
113
, within the bore
110
of the connector
107
.
If and when this prior art pen
100
takes a position where its penpoint tip
105
faces upwards, then the valve body
108
will contact and rest on the valve seat
111
in a manner shown in FIG.
25
(
a
). Consequently, a central opening through the valve seat
111
will be stopped so as to prevent the ink in the penpoint tip
105
from flowing backward therefrom.
However, the penpoint tip
105
may be positioned to face down-wards so that the valve body
108
leaves the seat
111
, then engages with and stands still on the lugs
113
as shown in FIG.
25
(
b
). The ink in the reservoir
106
will thus move towards the penpoint tip
105
, flowing through gaps that exist between the valve body
108
and the lugs
113
.
In the prior art ball-point pen
100
, its spherical valve body
108
is movable fore and aft within the valve chamber
115
, in response to whether the pen stands upright or whether reversed upside down. Thus the ink is permitted to flow forward towards the penpoint tip
105
, but is inhibited from flowing backward towards the ink reservoir
106
. This structure will diminish the problem of “scratchy first strokes”.
In the pen
100
known in the art, an inner periphery of the bore
110
extending through the connector
107
serves as a peripheral wall of the valve chamber
115
. Unfavorably, it is difficult for the valve chamber
115
thus formed to be of a sufficient preciseness.
In detail, the connector
107
may usually be formed by the injection molding such that the lugs
113
protruding from its inner periphery renders ‘undercut’ a region where the valve chamber
115
is located. Therefore, a wrenching force will unavoidably be applied to such a region of the valve chamber
115
when removing those connectors from an injection mold, thus failing to provide them with an unvarying accuracy in dimension and thereby lowering the highest possible precision.
It also is difficult to design and adopt an optimum clearance between the valve chamber
115
and the valve body
108
in such a prior art ball-point pen
100
. If the clearance is too small, then the valve body
108
moving within said chamber will sometimes be stopped therein at an intermediate position. In a case wherein the clearance is too large, the valve body
108
will possibly rock transversely and undesirably fail to rest tightly on the valve seat
111
.
The other prior art ball-point pens likewise suffer from the same or similar problems. In each of the ball-point pens known from the Publications or Gazettes listed above, an internal surface of the connector is utilized as the periphery of the valve chamber. This will result in a lower dimensional accuracy of the valve chambers thus formed. Accordingly, there will be involved a difficulty in predetermination of an appropriate clearance between each valve chamber and the valve body, thus failing to ensure smooth motion of the valve body.
In view of the problems inherent in the prior art, a primary object of the present invention is to provide a ball-point pen such that its valve chamber is formed with an epoch-making accuracy in dimension and such an improved accuracy will in turn enable optimization of the clearance between a valve body and the valve chamber, whereby the valve body thus rendered capable of moving more smoothly will afford a smoother hand-writing.
DISCLOSURE OF THE INVENTION
The present inventors have made various researches and studies to achieve the object just described above, and from a fundamental aspect of the present invention, it now provides a structure such that a penpoint tip has a region of an increased inner diameter for receiving a valve body partially or wholly, as disclosed in our basic patent application (No. Hei.9-349938) filed with the Japanese Patent Office. The ball-point pen provided herein from the fundamental aspect does comprise the penpoint tip having a distal end in which a writing ball is secured and having an ink-feeding bore extending through and axially of the penpoint tip, an ink reservoir for holding therein an amount of an ink, a connector for connecting the pen-point tip to the reservoir, a communicating bore formed through the connector so as to communicate with both the ink reservoir and the penpoint tip, and a valve seat formed in the communicating bore such that a valve body moving axially of the pen is allowed to rest on and engage with the valve seat. This ball-point pen is characterized in that the penpoint tip has an increased-inner-diameter region that is formed in and adjacent to an opening of the ink-feeding bore and located in the connector so that the valve body is capable of transferring partially or wholly into the ink-feeding bore, and that the ink-feeding bore has an engagement portion capable of engaging with and stopping the valve body in such a manner that interstice(s) for passage of the ink is provided between the engageme

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