WO2004009374A2

WO2004009374A2 - Writing implement cap

Info

Publication number: WO2004009374A2
Application number: PCT/GB2003/003293
Authority: WO
Inventors: Michael Devine
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-07-24
Filing date: 2003-07-23
Publication date: 2004-01-29
Anticipated expiration: 2005-01-24
Also published as: GB0217102D0; AU2003260709A1; AU2003260709A8; WO2004009374A3; GB2391166A

Abstract

A writing implement for use with a writing implement such as a pen having a pen nib, the cap having a sealed end comprising a membrane of resiliently flexible material having an elongate slit formed therein, wherein the membrane is constructed and arranged so that the slit is closed so as to form a substantially airtight seal when the nib is within the cap and the nib protrudes through the slit out of the cap through the opened slit to allow the pen to write.

Description

A WRITING IMPLEMENT CAP

The present invention relates to writing implements such as pens, and in particular although not exclusively to writing pen caps for felt-tip pens.

Conventional felt-tip pens comprise an ink reservoir into which protrudes one end of a nib formed from closely interwoven fibres. Ink is moved by capillary action out of the reservoir along the nib, to the opposite, end thereof, which can then be used to transfer the ink to a writing surface. In many felt-tip pens the whole reservoir is filled with fibres soaked in ink.

In normal operation the writing end of the nib will always be saturated with ink. When exposed to air this ink will evaporate, leading to drying out of the nib. This in turn leads to the nib becoming clogged up with dry ink, and prevents the pen from writing normally.

Traditionally, this problem is overcome by the provision of a removable cap which is placed over the pen nib when the pen is not in use and which is removed from the pen when writing. The cap provides an airtight seal which prevents evaporation of ink, and this keeps the writing end of the nib wet.

Such removable caps have the problem that many users forget to replace the cap once they have finished writing. This means that the nib may be exposed to the air for a considerable period of time, leading to drying out. The cap may become lost entirely.

Furthermore, many felt-tip pens are designed for use particularly by children. Easily detachable caps are particularly likely to become lost if a pen is regularly used by children. In addition, the caps themselves are small and could easily be inadvertently swallowed, thus causing a health risk. It is therefore desirable to provide a pen cap for use with a pen whose nib can be protected from drying out without the use of a conventional cap.

In accordance with a first aspect of the present invention there is provided a writing pen cap for use with a pen having a pen nib, .the cap having a sealed end comprising a membrane of resiliently flexible material having an elongate slit formed therein, wherein the membrane is constructed and arranged so that the slit is closed so as to form a substantially airtight seal when the nib is within the cap and the nib protrudes through the slit, out of the cap through the opened slit to allow the pen to write.

The cap is therefore attached to the pen when the nib is within the cap and whilst writing. When the nib is in the retracted position contained within the cap, the membrane seals the open end of the housing, preventing air leaving the cap and thus preventing evaporation from the nib.

The membrane is preferably constructed and arranged so that the pen nib can be pushed through the slit to move from a position within the cap a writing position. Because the membrane is_. formed of a resiliently flexible material it may be pushed aside by the pen nib itself.

The slit is preferably formed in a sigmoid shape. This increases the length of the slit for a given size of membrane, which reduces the resistance when the nib is pushed through it Furthermore the surface area of resilient material each side of the slit is increased, increasing the likelihood of an airtight seal being produced when the nib is retracted. In order to further increase this surface area, the angle of the slit may vary along the length of the slit

The resiliently flexible material may comprise rubber or a silicone elastomer. If a cap is lost or not replaced any uncovered nib of a writing implement can mark or stain articles when brought into contact therewith. For example, a ball point pen with an exposed nib in a shirt pocket would stain the clothing.

Accordingly, another aspect of the present invention provides a writing implement cap for use with a writing implement having a nib, the cap comprising an open-ended tube slidably mounted in a barrel of the writing implement and movable between a first position in which the tube shields the nib of the writing implement and a second position in which the tube exposes the nib of the writing implement to allow use thereof.

Some preferred embodiments of the invention will now be described by way of example, only and with reference to the accompanying drawings, in which:

Figure 1 is a cross sectional view of a pen with a nib in a retracted position;

Figure 2 is a top view of the pen of Figure 1 ;

Figure 3 is a cross sectional view of the pen of Figure 1 with the nib in an extended position;

Figure 4 is a top view of the pen shown in Figure 3;

Figures 5 A, 5B and 5C are cross sections through the seal shown in Figure 2;

Figure 6 is a cross-section through a pen and cap combination embodying the present invention; and

Figure 7 is a detail of the cap of Figure 6. Figure 1 is a view of an exemplary felt-tip pen 1. The pen 1 comprises a generally cylindrical outer housing 2, inside which is slidably received an_. inner housing 3, shown here in a retracted position. The inner and outer housing may be fabricated from any suitable material, for example moulded plastics. The inner housing 3 includes an ink reservoir 4 which extends most of the way therethrough. A nib 5 is inserted into the top end of the inner housing 3 so that a writing end 6 protrudes from the top of the inner housing 3, the other end 7 extending downwards into the ink reservoir 4. It will be understood that "top" and "bottom" refer to the pen only when in the orientation shown in Figure 1. Ink is moved by capillary action along the nib 5 from the reservoir 4 to the writing end 6.

The outer housing 2 has at least one open end 8, shown at the top in Figure 1. This allows the inner housing to be moved forward so that the writing end 6 of the nib 5 protrudes beyond the outer housing 2. The open end is sealed or closed by a membrane 9 of silicone elastomer having a slit 10 formed therein, as shown in Figure 2. The silicone is resiliently flexible, and the edges of the slit form an airtight seal against one another when the seal is in the form of a flat disc as shown in Figure 1.

As can be seen from Figure 2, the slit 10 in the seal 9 is generally in the form of a sigmoid shape. This enables the length of the slit 10 to be increased for a given diameter of the outer housing 2. The slit may be formed as an "S" shape or a "Z" shape, or any suitable configuration for increasing the length of the slit.

Returning now to Figure 1, an optional seal ring 11, formed for example of rubber, may be provided between the inner housing 3 and outer housing 2.

When the pen is in the retracted position shown in Figure 1, a sealed, chamber

12 is thus formed between the seal ring 11 and the seal 9. Since the writing end 6 of the nib 5 is contained within this sealed chamber 12 there will be very little evaporation of ink. Alternatively a close fit between the inner housing 3 and outer housing 2 may render the seal ring 11 unnecessary.

When it is desired to use the pen for writing, the inner housing 3 is pushed forwards through the outer housing 2. As this movement takes place, the writing end 6 of the nib 5 makes contact with the flexible seal 9 and pushes through, the slit 10, thus exposing it so it can be brought into contact with a writing surface, as shown in Figure 3 and Figure 4. The length of the slit 10, increased by its "S" shape, facilitates the opening of the slit 1 0 caused by moving the nib 5 therethrough.

When the user has finished writing, the inner housing 3 is pulled back through the outer housing so that the writing end 6 of the nib 5 passes back through the seal 9 into the sealed chamber 12. The slit 10 closes under the resilience of the seal material so that it again forms an airtight seal, and the pen returns to the configuration shown in Figure 1.

In preferred, configurations, some of the wet ink rubs off the sides of the nib 5 as it .is withdrawn through the slit. Although this is not essential, the wet ink on the sides of the slit enhance the seal formed as the slit closes.

Figures 5A to 5C show cross-sections through an optional modification of the seal 9 at three points along the length of the slit 10. Figure 5 A shows the seal at opposite ends of the slit 10, and Figure 5B shows a cross section at the centre of the slit 10. The angle of the sides of the slit changes along the length of the slit, thus increasing the area of resiliently flexible material forming the seal. As shown in Figures 1 and 3, the inner housing 3 also includes upper and lower ridges 13, 14 and a downwardly facing shoulder 15 arranged circumferentially around the outer surface thereof. The outer housing 2 includes upper and lower grooves 16, 17 and an upwardly facing shoulder 18 arranged around its inner surface. When the inner 15 housing 3 is in the retracted position shown in Figure 1, the downwardly facing shoulder 15 on the inner housing 3 abuts the upwardly facing shoulder 18 on the outer housing and prevents the inner housing from moving any further downwardly than the position shown in Figure 1. Furthermore, the upper ridge 13 mates with the lower groove 17 to hold the inner housing in position in the outer housing 2.

The outer housing is formed of sufficiently resilient material that the upper ridge 13 can be forced out of the lower groove 17, and the whole of the inner housing pushed forward so that the upper and lower ridges 13, 14 mate with the upper and lower grooves 16, 17, respectively, when the inner housing is' in the extended position as shown in Figure 3. An upwardly facing shoulder 19 on the inner housing 3 then abuts the base 20 of the outer housing 2 to define the limit of the upward movement.

Referring now to Figures 6 and 7, the cap 30 of the invention is readily useable with felt-tipped pens and the like of substantially conventional structure. Like numerals for like parts are used. Little modification of the barrel 31 of a conventional felt-tipped pen 32 is required save to add appropriate ridges or grooves (akin to ridges 13,14 and/or grooves 16,17 of Figures 1 and 3) to the barrel 31 to co-operate with the engagement means on the inner surface of the cap 30 so that the cap 30 is securely held in two positions: a storage position with the nib 5 within the cap 30; and a writing position with the rib 5 protruding through the slit 10. The cap 30 is slidable between these two positions. It is envisaged that caps 30 embodying the present invention can be adapted or fitted to conventional felt-tipped pens or the like so that the conventional and detachable cap is dispersed with. The cap embodying the present invention remains attached to the pen when in both the storage positiion and the writing position.

It will be appreciated .that ^' variations from the above described embodiment may still fall within the scope of the invention. For example, the resiliently flexible material forming the seal 9 has been described as a silicone elastomer, but it could be rubber or any other material which naturally forms a seal.

Furthermore, although the embodiment described above is a felt-tipped pen, the invention may be used with any form of pen or writing implement where evaporation of ink from the nib is a problem.

The seal can be dispensed with entirely for writing implements that do not suffer from ink evaporation to such a great extent, for example, disposable ball point pens. In such embodiments, the cap 30 is slidably mounted to the writing implement as shown in Figures 6 and 7 and can be slid along the barrel 31 of the writing implement 32 between the writing position in which the nib 5 is exposed and the storage position in which the nib 5 is shielded by the cap so ^' that the nib cannot readily come into contact with other articles. The cap 30 is essentially a tube open at both ends. The tube can be shaped at its free end adjacent the nib 5 to conform to the shape of the barrel of the writing implement adjacent the nib 5.

In addition, the nib. may be extended and retracted using any suitable mechanism, and it will be understood that the system described employing . ridges and grooves to hold the inner housing in place is exemplary only. In the present specification "comprises" means "includes or. consists of and "comprising" means "including or consisting of.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A writing implement for use with a writing implement such as a pen having a pen nib, the cap having a sealed end comprising a membrane of resiliently flexible material having an elongate slit formed therein, wherein the membrane is constructed and arranged so that the slit is closed so as to form a substantially airtight seal when the nib is within the cap and the nib protrudes through the slit out of the cap through the opened slit to allow the pen to write.

2. A cap as claimed in Claim 1, wherein the membrane is constructed and arranged so that the pen nib can be pushed through the slit.

3. A cap as claimed in Claim 1 or 2, wherein the slit is formed in a sigmoid shape.

4. A cap as claimed in Claim 1, 2 or 3, wherein the angle of the slit varies along the length of the slit.

5. A cap as claimed in any preceding claim, wherein the resiliently flexible material comprises rubber.

6. A cap as claimed in any of Claims 1 to 5, wherein the resiliently flexible material comprises a silicone elastomer.

7. A writing implement cap for use with a writing implement having a nib, the cap comprising an open-ended tube slidably mounted in a barrel of the writing implement and movable between a first position in which the tube shields the nib of the writing implement and a second position in which the tube exposes the nib of the writing implement to allow use thereof.

8. A cap according to any preceding claim, wherein the end of the cap is shaped to conform to the shape of the writing implement adjacent the nib.

9. A cap according to any preceding claim in combination with a pen.

10. A combination according to Claim 9.

11. A cap substantially as herein described with reference to Figures 1 to 7.