[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 portions 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 which falls under Art.54(3)EPC 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 the 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.
[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, arid has improved safety properties to guarantee
with a minimum risk of injuries of a person who swallowed the cap, sufficient air
for breathing to flow along the cap.
[0005] According to the invention this problem is solved by a cap for a writing instrument
containing ink, having safety ventilation meams enabling an air flow along the cap,
if the cap has lodged in a person's windpipe when swallowed accidentally, the cap
being closed on all sides with the exception of an insertion end, 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, said ventilation path being formed by a pair of axial
ribs projecting from the outside of the cap and arranged parallel to each other at
a distance with an air passage formed therebetween, in which said ribs being closely
spaced to define an air passage therebetween of a mimimum cross-sectional area of
3.4 mm² and having outer side faces tangentially and substantially continuously merging
into the peripheral surface of the cap.
[0006] Accordingly the ventilation path is defined by the channel formed between the ribs.
When the cap is swallowed, the windpipe can span across the channel, so that an air
passage of a certain mimimum cross-sectional area remains. On the other hand the ribs
are not spaced apart from each other at such a distance that there would be a risk
that the windpipe could be drawn into the channel which might result in infuries and
clogging of the windpipe. Further as another measure to avoid injuries of the windpipe,
the outer side faces of the ribs are formed in manner that they circumferentially
extend and merge into the surface of the cap in a smooth manner.
[0007] A feature of the caps according to the present invention is the 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 corresponds in their sealing
function to convential 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 any cavities which are not easily accessible, as well as an improved
safety function, in that the portions of the caps, which are citical, can readily
be checked at a glance as regards their functional state. A further advantage is the
relatively high freedom as regards the design of the caps.
[0008] The invention will be described in detail hereafter with reference to a preferred
embodiment and the drawings. In the drawings, identical or similar parts bear the
same reference numerals.
Figure 1 is a perspective view of a safety cap according to the invention,
Figure 2, 3 and 4 show the safety cap according to Figure 1 in general view, plan
view and view from the left.
The safety cap according to the invention is based on the presence of a pair of ribs
on the cap surface extending axially and projecting substantially radially, which
ensure that if the cap is swallowed, the windpipe cannot come into contact with its
surface along the entire periphery.
[0009] In the drawings the reference numeral 101 relates to the cap, which is substantially
cigar-shaped and whereof the outer diameter normally amounts to no more than 16 mm.
The reference numeral 102 relates to a pair of projecting ribs formed on the outer
surface of the cap 101, which extend axially along the cap. The open insertion end
of the cap 101 bears the reference numeral 104. As illustrated, an outer annular end
face may remain between the insertion opening 104 and the facing end of the ribs 102,
which end face has an axial length which should not exceed 2 mm.
[0010] The outer side faces 101 of the pair of ribs 102 extending in parallel one beside
the other at a distance apart are shaped so that they pass tangentially or continuously
into the outer surface of the cap 101, so that the airway is defined substantially
solely by the passage 106 enclosed between the ribs 102. The shaping of the side faces
110 of the ribs reduces the danger of injury to the windpipe or gullet, if the cap
101 is swallowed accidentally. The cap 101 in the present embodiment may have a substantially
cylindrical shape.
[0011] If the cap 101 is fitted to a writing instrument containing ink (not shown), as in
the aforedescribed embodiments, the interior of the cap is hermetically sealed and
consquently drying-up of the writing point is effectively prevented. If the cap 101
is accidentally swallowed, an axial airway remains between the side faces of the ribs
102. In conjunction with a covering placed around ist, the airway creates a cross-sectional
area for the passage of air, which due to suitable dimensions of the ribs 102 is designed
such that it amounts to at least 3.4 mm², preferably 6.8 mm² at each axial point of
the cap 101.
1. A cap for writing instruments containing ink, having safety ventilation meams enabling
an air flow along the cap, if the cap has lodged in a person's windpipe when swallowed
accidentally, the cap being closed on all sides with the exception of an insertion
end (4), 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, said ventilation path being
formed by a pair of axial ribs (102) projecting from the outside of the cap and arranged
parallel to each other at a distance with an air passage (106) formed therebetween,
characterized in that said ribs (102) being closely spaced to define an air passage
therebetween of a mimimum cross-sectional area of 3.4 mm² and having outer side faces
(110) tangentially and substantially continuously merging into the peripheral surface
of the cap (101).
2. A cap according to any one of the preceding claims, 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).
