Note: Descriptions are shown in the official language in which they were submitted.
W093J05966 PCTJGB92/01691
MARKING INSTRUMENTS ,'-
This invention relates to marking instrwments and
is especially concerned with such instruments, e.g.
pens and markers, having a tip to which a liquid is
supplied from a reservoir to be applied onto a
substrate, such as a sheet of paper, by means of the tip
which is moved over the surface of the substrate ~o
leave a liquid t~ace.
: In the case of pens, a variety of different tip
forms are known in the art and include rolling balls,
nlbs, wire nibs, fibre tips, felt tips and others. For
markers broad blade felt or fibre tips are most common
due to the desire to lay down a wide b~nd of liquid.
Many of the kno~n tips and the feed mechanisms which
deliver and control the flow of liquid to the tips
~ suffer from one or more of the following drawbacks:-
;~ i) dry-out as a result of liquid drying up at the tip
E : ~ andjor in ~he feed mechanism, with the result that the
marker is slow and/or difficult to prime, which can be
! ~ very inconvenient to the user;
; ii) drops of liquid-can be thrown from the tip if the
instrument is dropped or subjected to a flicking actioni
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W093~059S~ PCT/GB92/016;
iii) ink leakage can occur if the pen is subjected to
temperatures and/or pressure changes;
iv) unless the surface of the substrate is ~mooth,
there can be a harsh feel due to the tip being rigidly
fixed relative to the body which is gripped in the hand
of the user.
The pr~sent invention aims to provide a marking
instrument ~hich alleviates these drawbacks and an
instrument according to the invention comprises a body,
a liquid r~servoir chamber defined within the body, a
liquid feed device defining a channel for conducting
liquid from the reservoir to a marki~g tip, valve means
for controlling communica~ion between the reservoir
chamber and the feed channel, and an elastomeric member
partly confining the reservoir chamber and supporting
the feed device with respect to the body, whereby the
feed device is retractable relative to the body under a
force exerted against the tip by applying the tip
against a substrate and in response to such retraction
the reservoir chamber is pressurised by deflection of
~he elastomeric member and the valve means is opened to
allow liquid to enter the feed channel from the
reservoir.
In the normal condition, iOe. when there is no
force exerted on the tip to retxact the feed device, the
valve means is closed and flow of liquid from the
reservoir to the tip is positively precluded. The
retraction of the feed device caused by applying the tip
against a suhstrate lightly pressurises the reservoir
and has the effect of pumping liquid into the feed
channel to ensure a rapid supply of ink to the tip even
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in a situation where liquid may have dried up in the
delivery system between the reservoir and the tip. The
elastomeric member provides an effective hydraulically
damped spring suspension for the tip so that the tip is
easily able to follow surface irregularit~e~rwith the
result tha~ the instrument has an improved feel compared
with prior art instruments with fixed tips.
In accordance with a preferred and especially
advantageous feature the valve means is defined by
direct cooperation between the elastomeric member and
the feed device. The feed device may have a seat with
at least one port which is normally closed by the
elastomeric member and which is opened upon the
elastomeric member flexing under displacement of the
feed device. A valve arrangement o~ this form is simple
in operation and inexpensive to manufacture. The
elastomeric member serves several functions including
that of the valve me~ber.
In a particularly convenilent construction the feed.
device defines a radially directed valve part and the
elastomeric member has an aperture through which the.
feed device extends so that an inner peripheral surface
of the elastomeric member cooperates with the valve
seat.
Marking instruments constructed in accordance with
the invention may be equipped with a variety of
different tips and the invention is not limited to any
particular type of tip.
A more complete understanding of the invention will
be had from the following detailed description given
with reference to the accompanying drawings in which:-
~ igure l is an axial section through a markinginstrument embodying the invention;
Figure 2 is an enlarged scale cross-section of the
forward end part of the instrument;
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Figures 3 and 4 are views similar to Figure 2 and
illustrating modified forms of elastomeric mem~er;
Figure 5 is an axial cross~section through a
forward end portion of a fibre tip pen according to the
invention, the valve being shown in a closed~condition;
Figure 6 is a view corresponding to Fiyure 5 but
with the valve shown open;
Figure 7 is a longitudinal cross-section throu~h a
forward end part of a fibre tip highlighting marker in
accordance with the invention, the valve being shown
closed;
Figure 8 shows the fibre tip marker of Figure 7
with the valve opened;
Figure 9 is a longitudinal cross-section through
forward end part of another pen embodying the invention;
Figure 10 is a cross-secti.on through the feed
device of the pen shown in Figure 9, taken in the plane
X--X
Figure 11 is a view similar to Fig. 9 illustrating
a modified pen construction;
Figure 12 in scrap cross-section showing a modified
porting arrangement;
Figure 13,shows the device of Fig. 12 partly in
plan; and
Flgures 14/ 15 and 16 illustrate alternative ~ip
constructions.
The marking instrument shown in Figures 1 and 2 has
a ~ody comprising a cylindrical barrel 1 closed at its
rear end by a plug 2 provided with an air venting hole
3. At its forward end the barrel has a counterbore
terminating in a forwardly directed radial shoulder 5
which defines a seat for the peripheral portion of an
elastomeric member 6 which has the form of a circular
disc washer or diaphragm made of silicone rubber. The
washer is held clamped against the shoulder 5 by a
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W093~05966 ~ fi ~ PCT/GB92/01691
sleeve insert 8 fitted tightly into the end of the
barrel. Received in the sleeve and guided thereby for
axial sliding movement is a piston 9 having opposed
frustoconical ends, the forward end defining a marking
tip lO for contact with a substrate surface~and the
inner end defining a reduced central surface for contact
with the washer 6. A capillary restrictor 12 extends
through an axial bore formed in the piston to define a
capillary channel 14 for delivering a controlled flow of
marking liquid to the tip lO, this restrictor projecting
rearwardly of the piston. Closely surrounding a rear
end portion of the restrictor is a sleeve 15 which acts
as a valve seat for cooperation with a valve member
constituted by an inner edge of the washer 6. Thus, the
sections of the restrictor 12 and sleeve 15 protruding
from the rear end of the piston extend through a central
aperture in the washer, and these sections are provided
with a plurality, e.gO four raclial ports 16 which
co~m11nicate with the capillary channel of the restrictor
and open at the surface of the valve sleeve. The inner
end of the channel 14 is sealecl off ~y a plug 13. In
the normal condition when the marker is not being used,
~ the washer 6 covers and closes the ports 16 from
comm11nication with a liquîd reservoir ch~er 17 for
: marker fluid defined in the barrel and confined at the
forward end by the washer 6. The rear end of the
reservoir chamber is closed by an ink follower 20, such
as a grease plug or an elastomeric member, which moves
along the barrel behind the fluid as it is used up so
that measures to allow air to enter the reservoir
: chamber are not necessary. In the normal condition of
the pen the valve is tightly closed and the fluid within
the reservoir chamber 17 is protected against drying
out. In addition, if the instrument is flicked or
dropped fluid is prevented from passing from the
reservoir chamber.
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W093/05966 ~ ~ i3 ~ ~ PCT/GB92/016
When the instrument is to be used and the tip lO is
applied against a substrate surface, the piston 9
retracts into the barrel against the resilience of the
washer 6, the rear end of the piston pressing on the
inner ed~e region of the washer and causi~-the washer
to flex inwardly. The resilient deflection of the
washer has two impor-tant effects. Firstly, the aperture
in the washer expands and the ports 16 are uncovered to
open up communication between the reservoir chamber 17
and the capillary channel 14, thereby allowing fluid to
flow from the reservoir to the tip to be laid down onto
the substrate. Secondly, the movement of the washer
lightly pressurises the fluid within the reservoir
chamber producing a pumping action to ensure a rapid
delivery of fluid to the tip. Of course, when the force
on the tip is removed e.g. due to it being lifted away
from the su~strate, the restoring force applied by the
elastomeric washer displaces the piston forwardly and
ensures the valve closes again.
As shown in Figure 2 the washer 6 has the form of a
plain disc, but this is not essential and the
- elastomeric me~ber may be configuxed as required to
obtain the desired flexing characteristics for opening
and closi~g the valve and the resista~ce against tip
retr~ction. In Figures 3 and 4 for axample the washers
are shown to have annular grooves 20, in the first case
located near the outer edge and in the s~cond case
nearer the inner edge.
Shown in Figures 5 and 6 is a fibre tip pen
embodying the invention. The construction is largely
the same as that of the marker described above. The
washer is held in the barrel by a nose co~e 25 fitted in
the forward end and having an axial bore in which a
cylindrical piston 26 is accommodated. Extending
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through the piston is a fibre rod 27 with a free end
protruding through the leading end of the nose cone to
define a writing tip. The ports 16 in the valve sleeve
15 serve to deliver ink from the resexvoir chamber to
the rear end of the fibre rod when the va~v~ is opened
by a force exerted on the writing tip causing the feed
assembly consisting of the fibre rod, piston and valve
sleeve to retract and the washer 6 to flex, as shown in
Figure 6.
Illustrated in Figures 7 and 8 is a fibre tip
highlighter constructed according to the invention.
Again the valve arrangement is essentially as described
with reference to Figs. l to 4. The washer 6 is trapped
within the forward end of the barrel by a tubular nose
piece 30 fitted to the barrel. A fibre core 33 is
located within the nose piece and includes a head
portion which is slidably guided relative to the nose
piece by a bearing 34, the free end of the head being
arranged to protrude from the nose piece and being
shaped to define a broad ~dge for laying down a wide
line of marker fluid. The rear end of the core bears on
the central region of the washer 6 and is recessed to
accom~odate a ~central tube defining a feed channel 14
and the valve sleeve 15 surrounding the tube. When the
marker tip is pressed against a surface, the core 33
retracts and causes the elastomeric washer 6 to flex
rearwardly so that the valve is opened and the reservoir
chamber is pressurised, ~hereby fluid is supplied to the
core via the ports 16 and feed channel 14 and flows
along the ducts in the core to the tip to be laid down
thereby.
Figure 9 shows a pen embodying the invention with
the tip enclosed by a detachable cap 40. As in the
previous embodiments the barrel 1 is counterbored and
receives an elastomeric washer 6. Between the washer
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and the barrel shoulder, however, is held the flange of
a stop memb~r 41, the form and function o~ which are
described further below. The washer is retained in the
barrel by a nose cone 42 which has a central hole at its
apex. Slidably guided in this hole is a r0~-43 having
an axial capillary duct 44. The leading end of the rod
projecting from the nose cone defines a writing tip,
although the rod may in alternative embodiments serve to
deliver ink to a further tip component located at its
end. The rear end of the rod 43 is engaged in a sleeve
4S having a stepped ~ore and an ex-ternal shoulder which
abuts the washer 6 around its central aperture. Fitted
into the rear end of the sleeve which extends about half
way through the washer 6 is a pin 46 having a stem
portion received in the sleeve bore and an enlarged
head. Yormed on the radial shoulder between the stem
and head are spacer pips 48 (Fig. 10) so that a gap
defining a radially directed port is defined between
this shoulder and the confronting end face of the
sleeve. Furthermore, the stem of the pin has
longitudinal ribs 49 spaced therearound so that
longitudinal channels are de~ined between the stem and
~he inner surface (indicated ~y broken line 50 in Fig.
10) of the sleeve for conducting ink from the radial
port to the axial duct of the rod 43. The sleeve 45 and
pin 46 combine to form a ~alve seat with which the inner
peripheral portion of the washer 6 cooperates to control
ink flow to the writing tip from the reservoir cha~ber
17 enclosed in the barrel immediately behind the washer
6. The head of the pin projects rearwardly of the
washer and its rearward movement is limited by the stop
member 41 which is generally cup-shaped with holes 47 in
its planar end wall for passage of ink.
When the writing tip is pressed against a surface
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to be written on, the rod 43 retracts slightly moving
with it the valve sea~ formed by the sleeve 45 and pin
46 so that the inner periphery of the washer is
deflected rearwardly thereby pressurising the ink in the
reservoir chamber and opening the valve $o permit the
ink to pass to the writing tip. sy limiting the
rearward displacement, the stop mem~er 41 provides some
control over the pumping effect and hence the delivery
of ink to the tip. As shown the stop member is rigid
and defines a fixed stop, but it could be made resilient
to allow some additional rearward displacement under
increased forces applied against the writing tip.
Alternatively, resilient spring means may be provided on
the pin 46 for engaging the s-top member to
provide a gradually increasing resistance to further
rearward displacement of the writing tip as the pin 46
approaches the stop member. In this way a sudden stop
to retraction of the writing tip will be avoided. The
em~odlment shown in Fig. ll is provided with such spring
means in the form of leaf spring elements 55 integral
with the pin 46 and projecting outwardly therefrom in
rearwardly inclined directions. In this embo~iment the
periphery of the washer 6 is held between the forward
end of the stop me~ber 4l and an internal shoulder of
the nose piece 42 which extends over a front end por~ion
of the barrel 1. The stop member has a rearward
extension 57 within which is housed a porous pad 58
which serves as a damper. Thus, when the writing tip is
retracted and the central portion of the washer is
deflected rearwardly, flow of marker fluid from the sub-
chamber 59 defined between the pad 58 and the washer to
the main chamber 17 behind the pad is impeded by the pad
to enhance the initial pressurisation of the fluid in
the sub-chamber and hence flow of this fluid to the
writing tip through $he opened val~e. It will be
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appreciated that other means, such as a valve could be
used instead of the pad to enhance fluid pressurisation
and flow to the tip.
Another difference bPtween the pen of Flgure 11 and
that of Figure 9 is that the rod 43 is fitted with a
relatively short fibre rod 60 which defines the writing
tip. This construction allows the feed channels on the
upstream of the tip 60, i.e. the channel 44 and the
channels defined between the sleeve 45 and ~he pin 46 to
have larger flow areas, which facilitates effective
pumping of fluid all the way to the tip and which can
help to avoid any risk of the channels becoming blocked
due to dry out of marking fluid in the channels during
extended periods of non-use. Figures 12 and 13
illustrate a modified pin and sleeve assembly in which
large porting is conveniently provided for. The stem
portion of the pin 46 has a close fit in the sleeve and
is provided with two diametrically opposite longitudinal
grooves 62 running the full length of the stem. The
forward ends of these grooves are interconnected by a
groove 63 extending across the end face of the pin, this
groove also being in co~mllnication with the channel 44
passing through the ex~ruded rod 43. The rear ends of
the longitudinaï grooves 62 connect with radial grs~ ves
54 in the shoulder of the pin, these grooves defining
the valve ports which are con~rolled by the washer 6.
It will be appreciated that the precise form of the
tip and the feed mechanism for delivering fluid to the
tip from the valve are not important and hence the
invention is applicable to a wide variety of different
types of marking instrument. Shown in Figure 14 is a
roller ball tip assembly which may be fitted in~o the
sleeve 45 of the pens shown in Figs. 9 and 11 in place
of the rod 43. A ball housing 6S is telescoped together
with a feed rod 66 within a tubular case 67. The feed
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rod has an axial bore 68 which conducts marker fluid to
the ball 69. As shown a small secondary reservoir 70 is
defined by the ball housing immediately behind the ball,
but this may not be needed or could be given a greater
volume if required. Figure 15 shows an alternative tip
construction for a highlighter pen. The rod 43 has a
counterbore at its forward end and a fibre tip 72 has a
spigot inserted into the counterbore and an enlarged
head with a chisel blade edge for laying down a broad
line. An even more simple construction is depicted in
Figure 16 where the forward end of the rod 43 is fitted
with an overcap 74 of porous material forming a pad for
applying fluid to a substrate surface.
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