Coating implements with material supply – Material flows through porous tool – With flow-regulator
Patent
1998-01-28
1999-12-21
Bratlie, Steven A.
Coating implements with material supply
Material flows through porous tool
With flow-regulator
401148, 401273, B43K 518
Patent
active
060040580
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention is concerned with marking instruments of a kind in which a supply of marking fluid is stored in a reservoir and is delivered to a marking tip under control of a valve device arranged so that the reservoir is isolated when the instrument is not in use, e.g., so that leakage and/or dry out problems do not arise. The invention relates especially, but not necessarily exclusively, to writing instruments and is applicable to highlighter pens, felt tip pens, fibre tip pens, ball-point pens, roller ball pens and to pens of other types.
BACKGROUND OF THE INVENTION
In WO 93/05966 there is described a marking instrument having a valve device comprising a diaphragm with a central hole through which extends a feed member having a feed channel for conducting marking fluid to the marking tip. The inner end of the feed channel opens through radially directed ports which are normally closed by being covered by the inner peripheral surface of the diaphragm. For opening the valve, the feed member is adapted to retract under normal writing forces experienced due to the marking tip being applied against a surface, this retraction causing the diaphragm to deflect so that it lifts clear of the ports and thereby opens up communication between the feed channel and a reservoir chamber defined rearwardly of the valve. To ensure deflection of the diaphragm, its inner edge sits against a shoulder formed on the feed member. When the force against the marking tip is removed, due to the tip being lifted from the surface, the feed member is pushed forwardly by the diaphragm which closes the ports so that the reservoir chamber is once again isolated from the feed channel. It has been found that with some types of marking fluid, when the marking tip is lifted clear from a surface against which it has been pressed, marking fluid can continue to flow or ooze to the tip despite the diaphragm valve appearing to function correctly. Although the amount of fluid is small, the collection of excess fluid at the marking tip can detract from the performance of the marking instrument and is undesirable.
SUMMARY OF THE INVENTION
The present invention has the aim of providing a solution to the foregoing problem and in accordance with the invention there is provided a marking instrument comprising a feed member with a channel for conducting to a marking tip marking fluid supplied from a reservoir chamber, the channel having an inlet port at a peripheral surface of the feed member, a resilient valve member surrounding and arranged to seal against said peripheral surface for isolating the channel from the reservoir chamber, the feed member being retractable to deflect the valve member to open the port to the reservoir chamber, and a cavity defined between the valve member and the feed member to communicate with the port, deflection of the valve member in the opening direction causing the volume of the cavity to diminish and deflection in the other direction causing an increase in the cavity volume.
With the prior art diaphragm valve, when the diaphragm is deflected to open the valve a space can open between the diaphragm and the shoulder of the feed member and fill with marking fluid. The diaphragm moves to fill this space again when the feed member moves forwardly allowing the valve to close, and the marking fluid becomes displaced from this space and into the feed channel after the valve has closed. This is the cause of the oozing problem. By providing a cavity in accordance with the invention the tendency for marking fluid to be displaced into the feed channel after the valve has closed is eliminated and the problem is averted.
The cavity can be formed by a recess, e.g. a circumferential groove, in the peripheral surface of the feed member preferably located adjacent a shoulder provided on the feed member for abutment with the valve member. Alternatively, the cavity can be formed by shaping the valve member, such as by providing a valve diaphragm with a tapered surface for co-operation with the peripheral surf
REFERENCES:
patent: 2874679 (1959-02-01), Zeelouvitech
patent: 3589824 (1971-06-01), Andrews et al.
patent: 4364684 (1982-12-01), Kohno et al.
patent: 5332326 (1994-07-01), Hori
Bratlie Steven A.
Howley David A.
The Gillette Company
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