[0001] The invention relates generally to an improvement to caps for writing instruments
containing ink and in particular to a cap with a safety ventilation device in order
to facilitate an air flow along the cap, if the latter has lodged in a person's windpipe,
for example of a child, when swallowed accidentally.
[0002] In writing instruments which contain no ink, such as pencils and the like, hitherto
in order to prevent asphyxiation as a result of accidental swallowing, an opening
may be provided in the top of the cap covering the point of the pencil, so that if
the cap has lodged in a child's windpipe, air for breathing may continue to flow through
the cap, until medical assistance is given (see for example JP-A-39592/1986 and 118038/1977).
A transfer of this prinicple to a cap for writing instruments containing ink, in which
an evaporation of the ink must be prevented and the writing tip must be kept continuously
moist, is not readily possible, since due to this the function of the writing instrument
is jeopardised. In caps which serve to seal the writing tip of writing instruments
containing ink with respect to atmospheric air, the risk of asphyxiation therefore
exists in the case of accidental swallowing, such as is to be feared in particular
with children. Inter alia this risk has been expressed in a specification of the "British
Standard Institution", which is under preparation and dated June 23rd 1989, document
No. 89/38201.
[0003] It has already been proposed (see EP-A-0204252, JP-A-11016/1986), to provide an airway
in the cap, which however is sealed hermetically when the cap is fitted to the writing
instrument. It is typical of this type of safety caps that one or more perforations
are provided at one or more axial or peripheral points of the cap wall, which perforations
thus facilitate an exchange of air between the outside and inside of the cap. One
drawback of this solution is the complicated arrangement for achieving a sufficiently
tight encapsulation of the tip of the writing instrument, when the cap is fitted.
It is also known (DE-A-3728896), to provide a separate tubular air passage with open
axial ends and a cross-section closed peripherally all round, on the outside of the
cap, in order to separate the safety function from the sealing function. This solution
is not solely disadvantageous as regards the manufacturing difficulties connected
therewith, but in addition conceals the risk that in the course of time the air passage
is easily blocked by foreign bodies which have penetrated, such as food residues,
dirt deposits and the like and therefore the safety function can be lost. According
to EP-A-395 797 the ventilation path can be formed by a pair of axial ribs on the
outside of the cap, which are in a distance from each other which is greater than
the diameter of the cap body. In these circumstances there is a risk that the ventilation
channel between the ribs is clogged by drawn in portions of skin of the windpipe.
From EP-A-319 311 a safety cap is known which has also an axially extending ventilation
path on the outside of the cap underneath a clip which is connected to the cap in
a rigid, non-resilient manner. Finally from GB-A-2174374 a cap is known in which a
ventilation path is defined by a number of grooves axially extending on the outside
of the cap along an axial cap portion, which communicate with the interior of the
cap. Accordingly the interior of the cap, except for the insertion end, is not hermetically
closed as it would be desirable from the view point of an effective protection of
the writing part of a writing instrument against drying up. Further the design of
the grooves of the prior cap is such that the safety function of the cap is doubtful.
[0004] It is an object of the present invention to provide an improved safety cap having
a simple construction, which prevents drying up of the writing part of writing instruments
containing ink in an effective manner, and has improved safety properties to guarantee
sufficient air for breathing to flow along the cap.
[0005] According to the invention this problem is solved by a cap for writing instruments
containing ink, having a safety ventilation meams enabling an air flow along the cap,
if the cap has lodged in a person's windpipe when swallowed accidentally, said safety
ventilation means comprising at least one axial ventilation path on the outside of
the cap, which along at least part of its axial extension has an open cross-sectional
configuration, whereby when a covering is placed around the cap, a cross-sectional
area for ventilation in each radial plane is defined having a throughflow capacity
corresponding to the air requirement of a person, in which the cap being closed on
all sides with the exception of an insertion end, and in which said ventilation path
in combination being formed by a) a plurality of axial indentations or grooves formed
in the outer surface of the cap and spaced apart peripherally, and b) a substantially
plate-like retaining clip provided between an adjacent pair of axial indentations
or grooves.
[0006] A cap according to the present invention has a high sealing function resulting from
the fact that the caps are closed on all sides, i.e. there are no perforations leading
into the inside of the caps. The caps therefore correspond in their sealing function
to conventional caps used in writing instruments without a safety ventilation device.
Existing caps can therefore readily be replaced by safety caps according to the invention.
The construction of the safety ventilation device according to the invention has advantages
both as regards manufacturing techniques, since it is not necessary to form cavities
or perforations in the cap body which are not easily accessible, as well as an improved
safety function, in that the portions of the caps, which are critical, can readily
be checked at a glance as regards their functional state.
[0007] The invention will be described in detail hereafter with reference to an embodiment
and the drawings. In the drawings:
Figure 1 is a longitudinal sectional view of a safety cap according to an embodiment
of the invention, and
Figures 2, 3 and 4 show the safety cap according to Figure 1 in general view, plan
view and view from the left,
In Figures 1 to 4 the reference numeral 201 relates to a substantially cylindrical
cap with a closed axial top end and an open insertion end bearing the reference numeral
204. The outer diameter of the cap 201 normally amounts to no more than 16 mm. Attached
close to the top end of the cap 201 is a retaining clip 202, which is held by way
of a projection 207 formed on the surface of the cap 201, at a suitable distance from
the surface of the cap 201. Thus the writing part of a writing instrument (not shown)
if inserted through the insertion end 204 in the interior of the cap 201 can be hermetically
sealed against the outside. If desired, there may be provided within the cap 201 an
additional inner cap for receiving the front part of the writing instrument.
[0008] The reference numeral 206 relates to a number of indentations or grooves formed in
the outer surface of the cap 201, which extend along the cap from its top end to the
insertion end 204 and are distributed peripherally at a suitable distance from each
other. The free end of the retaining clip 2 may terminate at a distance m from the
insertion end 204, which distance should be not more than 2 mm.
[0009] A covering H placed around the cap 201 is indicated by the broken line in Figure
4. The covering H corresponds substantially to a windpipe in the region of a swallowed
cap 201. As shown in Figure 4, axial air paths are formed between the covering H and
the grooves or indentations 206, through which air for breathing can flow, because
at these portions a direct contact of the covering H or the windpipe with the surface
of the cap 201 is prevented. A pair of indentations or grooves 206 is provided adjacent
the retaining clip 202 laterally. The area 206 defined by the retaining clip 202,
the surface of the cap 201 and the covering H provides an enlarged air passage near
the retaining clip 202 for ventilation.
[0010] The cross-sectional area available as a whole for the ventilation in a radial plane
of the cap needs to be the same along the cap between the axial ends thereof. It is
important, howver, that a cross-sectional area for the ventilation is available at
each axial position of the cap which has a throughflow capacity coreresponding at
least to the minimum air requirement of a person. Experiments have shown that a minimum
cross-sectional area would be 3.4 mm², preferably 6.8 mm². Furthermore it is important
that the axial air paths on the outside of the cap have axial open ends which cannot
be clogged by a covering H placed around them, respectively by the the windpipe of
a person.
1. A cap for writing instruments containing ink, having a safety ventilation means enabling
an air flow along the cap, if the cap has lodged in a person's windpipe when swallowed
accidentally, said safety ventilation means comprising at least one axial ventilation
path on the outside of the cap, which along at least part of its axial extension has
an open cross-sectional configuration, whereby when a covering is placed around the
cap, a cross-sectionl area for ventilation in each radial plane is defined having
a throughflow capacity corresponding to the air requirement of a person, characterized
in that the cap (201) being closed on all sides with the exception of its insertion
end, and that said ventilation path being formed by a plurality of axial indentations
or grooves (206) formed in the outer surface of the cap and spaced apart peripherally,
and a substantially plate-like retaining clip (202) provided between an adjacent pair
of axial indentations or grooves (206).
2. A cap according to claim 1, characterized in that the cross-sectional area of the
ventilation path at any axial position of the cap (201) is greater than or equal to
3.4 mm².
3. A cap according to claim 1 or 2, characterized in that the ventilation path terminates
at a distance less than or equal to 2 mm from the insertion end (204) of the cap (201).
