The invention relates to an ink cartridge for a printer.
If a simple box filled with ink is used as an ink cartridge, ink will
escape in handling through the delivery aperture in the cartridge
and possibly also through the breather hole. The cartridge will
also leak if the ambient atmospheric pressure drops.
One known cartridge attempts to remove those problems by
providing a body of low capillary force sponge or foam material
which is saturated with ink and fills the entire cartridge. This
does mean however that the volume of ink that the cartridge can
hold is significantly reduced.
Another known ink cartridge is currently sold by Canon K.K. and
is disclosed in GB-A-2268911. The cartridge has two
compartments separated by a solid wall which reaches almost to
the floor of the cartridge. The front compartment to one side of
the wall includes a breather hole above a larger delivery aperture.
The front compartment is filled with a body of low capillary
action foam. The wall includes ribs extending into the first
compartment and leading to the lower edge of the wall. As ink is
withdrawn through the delivery aperture, air enters through the
breather hole. The cartridge achieves negative pressure by the
fact that ambient air has to pass through the opening between the
two compartments which is at the bottom of the cartridge when it
is installed on the machine. The ribs on the dividing wall allow
the air to pass by the foam in the first compartment to go under
the wall and into the second compartment. The ink in the foam
in the first compartment would effectively impede the passage of
tile air, were the ribs not there.
According to one aspect of the invention, there is provided an ink
cartridge for a printer, the cartridge including a body of capillary
material therein and bridging a breather hole in the cartridge and
a body of capillary material therein and bridging a delivery
aperture of the cartridge, and means for holding the bodies in
place to leave a storage volume behind them while permitting air
to pass through the bodies into the storage volume.
The cartridge can thus consist of a single, undivided compartment
and preferably has that configuration. Negative pressure is
achieved by the fact that ambient air has to pass from the breather
hole, and through the ink saturated material in order to replace
used ink in the cartridge. Each body has a sufficiently high
capillary force to result in a negative pressure within the cartridge
sufficient preferably to prevent any leakage of ink from the
cartridge during handling and in operation.
The means for holding the bodies in place may take any suitable
form and may comprise at least one projection, such as a rib,
preferably a pair of oppositely disposed ribs. The holding means
may comprise at least one strut across the cartridge. Preferably
the holding means covers less than three quarters of the body to
permit ready flow of air. Unlike the cartridge of GB-A-2268911
the holding means may be apertured at the top or centrally or may
define a regular or irregular array of apertures evenly or unevenly
distributed. The holding means may thus form a perforated
barrier.
The body of capillary material bridging the delivery aperture may
lie in contact with the part of the cartridge wall defining the
delivery aperture. The body of capillary material bridging the
breather hole may be spaced from the part of the cartridge
defining the breather hole so that there is a void defined between
the body and the part of the cartridge defining the breather hole.
Indeed, according to another aspect of the invention there is
provided an ink cartridge for a printer, the cartridge including a
body of capillary material bridging a breather hole of the
cartridge, the body being spaced from the part of the cartridge
defining the breather hole so that there is a void defined between
the body and the part of the cartridge defining the breather hole.
The body of capillary material bridging the breather hole may be
integral with the body of capillary material bridging the delivery
aperture. The bodies of capillary material may fill less than half
of the cartridge to improve the volume of ink which can be held
by the cartridge. Preferably the body or bodies are large enough
to provide the required negative pressure while providing the
largest volume for ink storage in the cartridge.
The cartridge may be relatively slim and flat, and may be
substantially rectangular. The cartridge may include at least one
strengthening member between the two largest faces of the
cartridge. This will prevent possible ink leakage as a result of
squeezing of the cartridge. The cartridge may comprise a zig-zag
array of strengthening members but in other embodiments the or
each strengthening member may take any suitable form and where
a plurality of strengthening members are provided they may be in
any convenient arrangement. At least one strengthening member
may lie perpendicularly to the largest faces of the cartridge. At
least one strengthening member may lie centrally of the cartridge.
Embodiments of the invention will now be described by way of
example and with reference to the accompanying drawings, in
which:
Fig. 1 is a side elevation in cross-section of the cartridge of
the first embodiment of the invention; Fig. 2 is a plan view in cross-section of the cartridge of
Fig. 1; Fig. 3 is a front elevation of a part of the cartridge of Fig.
1; Fig. 4 is a front elevation of a part of the cartridge in a
second embodiment.
The cartridge 10 of the embodiment is generally rectangular being
deeper than it is tall and taller than it is wide. The front wall 12
of the cartridge includes a smaller breather hole 14 above a larger
delivery aperture 16. A zig-zag arrangement of struts 18 extends
across the container 10 between the side walls 20,22 from the top
wall 24 to the bottom wall 26 of the container 10, substantially
parallel to the front wall 12 and mid-way between the front and
rear walls 12,28. The struts 18 form a unitary member 30 in the
shape of a plurality of "Z"'s one on top of the other. The strut
member 30 is held in position within the cartridge 10 by means of
four ribs 32,33, two on each side of the cartridge 10 which define
channels facing one another to receive the edges of the strut
member 30. A high density body of foam 34 is provided and fills
the front of the cartridge 10 abutting the walls of the cartridge 10
at the front of the cartridge except for the area of the front wall
12 around the breather hole 14, where there is a cylindrical recess
to provide a void behind the breather hole 14. The body of foam
34 extends rearwardly almost as far as the strut member 30 being
held in place by the front two ribs 32 and strut member 30. The
cartridge 10 is supplied to a user full of ink and with a seal over
the breather hole 14 and delivery aperture 16. The initial
conditions necessary to ensure negative pressure when the seal is
pulled from the cartridge, are achieved by sealing the cartridge
with a partial vacuum inside as it leaves the filling machine.
In use, ink will not leak out of the breather hole 14 or delivery
aperture 16 of the cartridge 10 while being handled by a user
because of the negative pressure in the cartridge and the capillary
force of the foam body 34. The cartridge 10 can be jolted or
dropped but the capillary force will ensure that ink does not
escape. Squeezing of the cartridge 10 which might otherwise
cause leakage is resisted by the struts 18 which act as
reinforcement in view of the relatively flat slim shape of the
cartridge 10. The void behind the breather hole 12 will fill with
air as the ink within the cartridge is removed through the delivery
aperture 16 providing further security against leakage. The
density of the foam will ensure that as ink is withdrawn in use
through the delivery aperture 16 negative pressure is maintained
in the cartridge due to the resistance to entry of ambient air
presented by the ink saturated foam bridging the breather hole 14.
The ribs 32,33 and struts 18 provide little or no barrier to
movement of air into the storage volume at the rear half of the
cartridge 10.
Fig. 4 shows an alternative to the strut member 30. The holding
member 40 in this case is in the form of a rectangular sheet 42
having semi-circular cut- outs 44,46. There is one cut-out 44 at
each end and a series of pairs of oppositely disposed cut-outs 46
along the sides of the sheet 42. The sheet 42 in place again
forms a perforated barrier to hold the foam body 34 and allow air
to pass readily through.