GB2249526A

GB2249526A - Safety cap far a writing instrument

Info

Publication number: GB2249526A
Application number: GB9123654A
Authority: GB
Inventors: Takashi Isoda
Original assignee: Mitsubishi Pencil Co Ltd
Current assignee: Mitsubishi Pencil Co Ltd
Priority date: 1990-11-07
Filing date: 1991-11-07
Publication date: 1992-05-13
Anticipated expiration: 2011-11-07
Also published as: GB2249526B; DE4136612A1; DE4136612C2; JPH0473589U; GB9123654D0

Abstract

The cap is formed of inner and outer caps (18, 6) between which ribs (13, 19) define air passages so that air can pass right through the cap to prevent asphyxiation if swallowed. When the writing tip (5) is inserted into the cap, the air that it displaces is vented through the air passages to prevent cyclical increases and decreases in pressure upon inserting and removing the writing tip (5) from causing liquid to be sucked out of the tip (5) and creating a mess. In the final stage of inserting the tip (5), the tip (5) pushes the inner cap (18) a short distance against the force of a spring (24). The in nor cap (18) contains an elastomer insert (23) which, with the spring (24), forms an air-tight seal around the tip (5) to prevent the tip (5) from drying out. <IMAGE>

Description

I- CAP FOR A LIQUID APPLICATOR 22495?0 The present invention relates to an

improved cap for the front end of a liquid applicator such as a writing instrument (e.g. a sign pen, a marker, an aqueous ball pen and the like) to prevent evaporation of the liquid (e.g. ink) contained therein.

Conventional caps are formed of resin materials which are good at preventing evaporation of the ink. They are put on the front end of the writing instrument, with the front end tightly inserted in an inner hole of the cap or an inner cap provided in the inner hole.

However, occasionally, depending upon the size and shape of the cap, a child may swallow the cap by mistake and because the cap is only open at one end the cap may block the throat, thereby resulting in asphyxiation.

Also, inserting the writing tip of the writing instrument into the cap, and removing it therefrom, raises and lowers the pressure to which the writing tip is exposed. This can cause ink to leak out of the writing tip, potentially dirtying a user's hands and clothes.

According to the present invention, there is provided a cap for covering a front end portion of a liquid applicator, the cap comprising: an outer cap having an inner hole with a first end and a second end, the second end being open for receiving therein the front end portion of the liquid applicator; an opening in the first end of the outer cap; a tube-like inner cap having a closed first end and an open second end and slidably mounted in the inner hole of the outer cap with the open second end of the inner cap facing towards the open second end of the outer cap, the inner cap being movable between a first position and a second position closer to the second end of the outer cap than the first position; biasing means for biasing the inner cap to move towards its second position; and air passage means between the inner and outer caps for providing one or more air passages between the opening in the first end of the outer cap and the second end of the inner cap whilst the inner cap is in its second position, whereby, with the inner cap in its second position, air can flow from the opening to the open second end of the outer cap to prevent asphyxiation if the cap becomes lodged in a person's mouth, throat or i trachea and whereby, during insertion of the front end portion of the liquid applicator into the cap, air displaced as an applicator tip of the free end portion moves from the second end of the outer cap to the point at which it is inserted into the second end of the inner cap and the free end portion starts to push the inner cap away from its second position is vented out of the opening via the air passage(s) so that the applicator tip remains substantially at atmospheric pressure.

Compared with the amount of air displaced as the applicator tip moves from the second end of the outer cap to the point at which it is inserted into the second end of the inner cap and the free end portion starts to push the inner cap away from its second position, the amount of air displaced as the free end portion pushes the inner cap from its second to its first position is usually comparatively small and unlikely to cause pressure fluctuation induced liquid leakage from the applicator tip if not vented andlor isolated from the applicator tip. Venting and not isolating this displaced air is the least favourable of the three combinations because, whilst preventing pressure fluctuation induced liquid leakage from the applicator tip, it leaves the applicator tip in communication with the atmosphere when the cap is fully fitted (i.e. when the inner cap has been pushed to its first position) and therefore the applicator tip may dry out.

Preferably, the inner cap includes sealing means for sealing the applicator tip within the second end of the inner cap to isolate the applicator tip from the air displaced as the free end portion pushes the inner cap from its second to its first position.

The invention will now be described by way of a non-limiting embodiment with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a writing instrument and a cap in accordance with the present invention; Fig. 2 is a perspective view showing the cap detached from the body of the writing instrument; Fig. 3 is an exploded perspective view showing the body and the cap, partly in vertical section; Fig. 4 is a half sectional view of the cap with the body completely inserted thereinto; Fig. 5 is a cross-section taken along the line V - V of Fig. 4; Fig. 6 is a cross-section taken along the line VI - VI of Fig. 4; and Fig. 7 is a half sectional view of the cap with the body partly inserted thereinto.

The embodiment of the present irivention is a cap for a writing instrument such as a sign pen, a marker, an aqueous ball pen, etc. and fits over the writing tip of the body of the writing instrument to prevent evaporation of ink therefrom. The cap is constructed so that, even if accidentally swallowed by a little child, it does not asphyxiate the child because an air passage is provided therein. Also, the ink does not leak from the writing tip or an adjacent air hole as a result of pressurization and depressurization of the writing tip upon insertion and removal of the body in and from the cap. Thus, there is no staining of the hands or clothing of the user. As shown in Figs. 3 - 7, plural ribs 13 are provided around the bottom of the side wall of an inner hole 10 of an outer cap 6. Through the bottom wall with a rear surface 15 of the outer cap 6, an opening 8 is formed, leaving a stepped portion 14. On the inner side wall of the cap 6 are formed f irst and second annular engaging protrusions 11, 12. There is housed in the outer cap 6 a tubular inner cap 18 whose rear end is closed to form a bottom portion 21. The inner cap 18 has a front end hole in which a closed bottom sealing member 23 of air-impermeable elastomer is inserted and a plurality of ribs 19 are formed around the front end outer periphery thereof. The inner cap 18 is inserted in the inner hole 10 of the outer cap 6 with a compression spring 24 positioned between the front end step portions 16 of the ribs 13 and the rear end step portions 20 of the ribs 19. The front end of the inner cap 18 is biased by the spring 24 against the engaging protrusion 12 provided on the inner side wall of the inner hole 10. The engaging protrusion 12 defines the limit of rearward movement of the cap 18. There are plural gaps 17 and 22 respectively between the outer periphery of the inner cap 18 and the ribs 13 of the inner hole 10 and between the inner hole 10 and the ribs 19 of the inner cap 16. The gaps 179 22 provide an air passage between the rear end opening 8 of the outer cap 6 and the front end of the inner hole 10 when the cap is not inserted on the body 2. Thus, air may flow through the cap from one end to the other.

On a front portion on a shaft 3 of the writing instrument body 2 is formed an annular engaging protrusion 4 and on the front end of the shaft 3 is provided a writing tip 5 of the type suitable for an aqueous ball pen or the like. In the body 2 is an ink reservoir (not shown) containing a liquid ink and a control device (not shown) for properly adjusting the flow of ink and for storing ink in response to changes in the internal pressure of the ink reservoir. The location of the annular engaging protrusion 11 of the cap is such that, when it engages the annular engaging protrusion 4 of the shaft 3 when the body 2 is inserted into the inner hole 10 of the cap, the inner cap 18 retracts by a distance S as shown in Fig. 4. The front portion of the writing tip 5 presses against the rear end wall of the sealing member 23 and the bottom portion 21 of the inner cap 18 is virtually flush with the rear end outer surface 15 of the outer cap 6.

As may be seen, when the body 2 is fully inserted in the cap as shown in Fig. 4, the front portion of the body is tightly inserted in the sealing member 23 with the writing tip 5 pressed against the rear end wall of the sealing member 23. Accordingly, the sealing member 23 prevents both the drying out of the writing tip 5 and the evaporation of ink frorn the air hole provided adjacent the writing tip. Furthermore, because the inner cap 18 retracts as the body 2 is inserted into the cap, the interiors of the cap and the sealing member are not pressurized. As the body 2 is removed from the cap, the inner cap 18 is pushed forwards by the restoring force of the spring 24 and keeps pace with the body 2 until the inner cap 18 hits the engaging protrusion 12, at which point the writing tip 5 starts to be withdrawn from the inner cap 18. However, because at this stage the opening 8 and gaps 17, 22 ensure that the writing tip 5 and associated air hole remain at atmospheric pressure and are not subjected to a negative pressure as the body 2 slides out past the seal provided by engaging protrusion 11, no ink is sucked out of the writing tip 5 or its associated air hole.

Furthermore, when the cap is off the body 2 an air passage is formed between the front end of the inner hole 10 and the opening 8, thereby preventing accidents such as asphyxiation and the like if the cap is swallowed by mistake and clogs the throat.

With the construction and function as described above, even if a little child swallows the cap by mistake and clogs his or her throat, there is avoided an accident such as asphyxiation and the like because air is able to pass through the interior of the cap since an air passage is provided between the rear end opening 8 and the front of the inner hole 10 of the cap. Furthermore, the construction which enables the cap to achieve this does not decrease the visual attractiveness of the cap. Also, since inserting and removing the body 2 does not cause pressurization and depressurization of the interior of the cap and the front portion of the body 2, there is prevented the problem of ink spots oozing out from the writing tip or the air hole and staining the hands or clothing of the user.

Claims

1. A cap for covering a front end portion of a liquid applicator, the cap comprising:

an outer cap having an inner hole with a first end and a second end, the second end being open for receiving therein the front end portion of the liquid applicator; an opening in the first end of the outer cap; a tube-like inner cap having a closed first end and an open second end and slidably mounted in the inner hole of the outer cap with the open second end of the inner cap facing towards the open second end of the outer cap, the inner cap being movable between a first position and a second position closer to the second end of the outer cap than the first position; biasing means for biasing the inner cap to move towards its second position; and air passage means between the inner and outer caps for providing one or more air passages between the opening in the first end of the outer cap and the second end of the inner cap whilst the inner cap is in its second position, whereby, with the inner cap in its second position, air can flow from the opening to the open second end of the outer cap to prevent asphyxiation if the cap becomes lodged in a person's mouth, throat or trachea and whereby, during insertion of the front end portion of the liquid applicator into the cap, air displaced as an applicator tip of the free end portion moves from the second end of the outer cap to the point at which it is inserted into the second end of the inner cap and the free end portion starts to push the inner cap away from its second position is vented out of the opening via the air passage(s) so that the applicator tip re-mains substantially at atmospheric pressure.

2. A cap according to claim 1, wherein the inner cap includes sealing means for sealing the applicator tip within the second end of the inner cap to isolate the applicator tip from the air displaced as the free end portion pushes the inner cap from its second to its first position.

3. A cap according to claim 2, wherein the sealing means comprises an elastically deformable sealing member defining the open second end of the inner cap.

4. A cap according to claim 3, wherein the sealing member includes an abutment surface spaced from the second end of the inner cap for sealing the front end of the applicator tip when inserted in the second end of the inner cap.

5. A cap according to claim 3 or 4, wherein the sealing member is rnade of elastomer.

6. A cap according to any one of claims 1 to 5, wherein the air passage means comprises a plurality of inwardly projecting ribs extending along the inner hole of the outer cap adjacent to the first end thereof and a plurality of outwardly projecting ribs extending along the outer surface of the inner cap adjacent to the second end thereof.

7. A cap according to claim 6, wherein the ribs of the outer cap are separated along the axis of the cap from the ribs of the inner cap and the biasing means is located in the axial gap between the two sets of ribs.

8. A cap according to claim 7, wherein the biasing -neans is a coiled compression spring.

9. A cap according to any one of the preceding claims, wherein the outer cap has a first annular protrusion within its inner hole for defining the second position of the inner cap.

10. A cap according to clairn 9, wherein the outer cap has a second annular protrusion within its inner hole, closer to the second end of the outer cap than the first annular protrusion, for engaging with the front end portion of the writing instrument to retain it within the cap once it has pushed the inner cap to its first position.

11. A cap according to any one of the preceding claims, wherein, when the inner cap is in its first position, its closed first end projects into the opening in the first end of the outer cap.

12. A cap substantially as herein described with reference to and/or as illustrated in the accompanying drawings.

13. A liquid applicator in combination with a cap according to any one of the preceding claims.

14. All novel features and combinations thereof.