Note: Descriptions are shown in the official language in which they were submitted.
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LIQUID CONTAINMENT AND DISPENSING DEVICE
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
This invention relates to a liquid containment and dispensing device.
More particularly, this invention relates to a liquid containment and
dispensing device
with a self contained pump. The device of this invention is useful for
containing and
dispensing printing ink in an ink jet printer.
2. DESCRIPTION OF THE PRIOR ART
Pending U.S. Patent Application Serial No. 08/429,987, now U.S. Patent
5,784,087 the disclosure of which is incorporated herein by reference, and
published
European Application EP 0 741 038 A2, which claims priority based on the
aeforesaid
U.S. Patent Application, describe a liquid containment and dispensing device
with a self
contained pump that was developed for use in containing and dispensing
printing ink in
an ink jet printer. The pump of the aforesaid device includes a linearly
acting pumping
member that reciprocates within a pumping chamber, which is defined by a
perimetrical
wall, and the pumping chamber is covered by a thin, flexible diaphragm, which
is
fabricated from a laminate of thin films. The diaphragm is then heat-staked to
a free edge
of the perimetrical wall that surrounds the pumping chamber.
The use of a flexible diaphragm fabricated from a laminate of films
requires great care in its heat staking to the perimetrical wall of a pumping
chamber,
however, due to the tendency of such a diaphragm to form wrinkles around its
outside as
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sufficient material is left in the central portion of the diaphragm to permit
it to flex
sufficiently to accommodate the pumping motion of the pumping member. Further,
the
use of heat-staking to secure the diaphragm to the perimetrical wall also
requires great
care in the control of the temperatures used in the heat-staking operation, as
excessively
high temperatures can degrade the thin films used in the diaphragm, while
excessively
low temperatures can result in a poor quality seal between the diaphragm and
the
perimetrical wall.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a liquid containment
and dispensing device, especially a liquid containment and dispensing device
that is
useful in containing and dispensing printing ink in an ink jet printer, with a
pumping
chamber cover that does not tend to wrinkle around its outside, where it is
joined to a free
edge of a perimetrical wall of the pumping chamber. Further, the invention as
described
above incorporates a crimped metallic ring to help secure the pumping chamber
cover to
the free edge of the perimetrical wall of the pumping chamber to augment the
seal that is
formed therebetween by heat-staking.
The elimination of wrinkles in the pumping chamber cover according to
the present invention is obtained by pre-shaping a sheetlike cover material by
a
thermoforming operation, to thereby provide a domed configuration to a central
portion
of the cover that results in sufficient flexibility to accommodate the
reciprocation of a
pumping element without requiring excessive material in the surrounding
portion of the
cover. In the preferred embodiment of the present invention, the cover is
formed from a
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sheetlike material that is a thin laminate of two or more polymeric films,
with a suitable
adhesive between adjacent layers of such laminate to prevent delamination of
the layers
thereof. At least one of the films is a material with good resistance to
oxygen and
moisture vapor transmission, such as ethylene vinyl alcohol copolymer (EVOH),
which is
preferably used in the interior of the laminate, with an innermost layer of a
low density
polyethylene (LDPE), which has good flexibility and bonds well to the
perimetrical wall
of the pumping chamber when the wall and the liquid containment and dispensing
device
chassis of which it is a part is formed from polyethylene by injection
molding. The
outermost layer of the pumping chamber cover is then formed from a high heat
resistant
polymer such as nylon (a polyamide material) for good resistance to abrasion
and to
prevent the film structure from sticking to the heat staking die.
Accordingly, it is an object of the present invention to provide an
improved liquid containment and dispensing device of a type that has a self
contained
pump. More particularly, it is an object of the present invention to provide a
liquid
containment and dispensing device as described above that has utility in
containing and
dispensing printing ink in an ink jet printer.
It is also an object of the present invention to provide an improved
pumping chamber cover for use in a liquid containment and dispensing device of
the type
described above.
For a further understanding of the present invention and the objects
thereof, attention is directed to the drawing and the following brief
description thereof, to
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the detailed description of the preferred embodiment of the invention and to
the appended
claims.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is an exploded, perspective view of a liquid containment and
dispensing device according to the preferred embodiment of the present
invention;
Fig. 2 is sectional view, at an enlarged scale, taken on line 2-2 of Fig. ;
and
Fig. 3 is a fragmentary view, at a further enlarged scale, of the element
illustrated in Fig. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A liquid containment and dispensing device according to the preferred
embodiment of the present invention is indicated generally by reference
numeral 10 in
Fig. 1. The liquid containment and dispensing device 10 is made up of a hard
protective
shell 12 that is closed at an end 12a, which will be the upper end when the
device 10 is
installed, for example, in an ink jet printer. A molded plastic chassis 14 is
installed in an
opposed, open end 12b of the shell 12, and the chassis 14 has a pumping
chamber 16
defined and surrounded by a perimetrical wall 18, which is formed integrally
with the
chassis 14.
A pumping element 20, shown fragmentarily, is positioned within the
pumping chamber 16 and is reciprocable therein, a coil spring 22 being
provided to bias
the pumping element 20 away from the closed end 12a of the shell 12. The
pumping
chamber 16 is closed by a cover or diaphragm 24, whose outer portion is heat-
staked to a
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free edge of the perimetrical wall 18 that surrounds the pumping chamber 16.
The
diaphragm 24 is then further secured to the perimetrical wall 18 by an
aluminum crimp
ring 26 to further ensure that the seal between the diaphragm 24 and the
perimetrical wall
18 remains secure throughout the life of the ink containment and dispensing
device 10.
Ink or other liquid is dispensed from the liquid containment and
dispensing device 10 by deflecting the central part of the diaphragm 24 to
deflect the
pumping element 20 within the pumping chamber 16, against the force of the
coil spring
20, to thereby pump the liquid from a flexible pouch (not shown), which is
secured to the
underside (in the illustrated arrangement) of the chassis 14 through a fluid
outlet portion
28 of the chassis 14. As thus far described, the liquid containment and
dispensing device
functions in the manner described in the aforesaid Serial No. 08/429,987 (EP 0
741
038 A2), except that the device of such reference does not disclose the use of
a crimp ring
corresponding to the crimp ring 26 of the device 10 of Fig. 1.
The device 10 of Fig. 1 differs further from the device of the aforesaid
reference in that the diaphragm 24 is preshaped, for example, by a
thermoforming
operation, to provide it with a domed central portion 24a and a planar
surrounding edge
portion 24b, which is the portion that is heat-staked to the perimetrical wall
18 on the
chassis 14. The diaphragm 24, thus, has sufficient excess material in its
central portion
24a without requiring excess material in its surrounding edge portion 24b to
be able to
flex as required during the pumping of ink or other liquid from the device 10,
as
described above. Such excess material can lead to wrinkling in an otherwise
planar
diaphragm, which can complicate the problem in properly heat-staking a
diaphragm to
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the free edge of a perimetrical wall of a liquid containment and dispensing
device of the
type described. Such wrinkling can also cause premature failure of the
diaphragm
material as a result of the flexing cycle.
As is shown in Fig. 2 and even more clearly in Fig. 3, the diaphragm 24 is
formed from a lamination of layers of polymeric materials of various
compositions. The
layers include an innermost layer 24c of any member of the polyethylene
material family,
such as LDPE, LLDPE, HDPE, metallocene PE, ethylene vinyl acetate and ethylene
ethyl
acrylate or blends thereof, preferably with a density in the range of
0.880g./cc.-
0.964g./cc. Any such material has good strength and flexibility and heat-
stakes well to
the perimetrical wall of the chassis 14 when the chassis 14 is formed of
polyethylene.
The diaphragm 24 also includes an intermediate layer 24d of a material with
good
resistance to gas and moisture vapor transmission, such as nylon and nylon co-
polymers,
PVDC and EVOH, which is the preferred material. The diaphragm 24 also includes
an
outermost layer 24e of a polymer selected for high melt temperature, abrasion
resistance
and flex life, such as nylon and nylon co-polymers and polypropylene. Since
the material
of the layers 24c, 24d, 24e, as described, do not bond well to one another,
preferably
layers 24f, 24g of an adhesive are provided between adjacent layers of the
diaphragm 24
to prevent the layers 24c, 24d, 24e from delaminating in service.
The diaphragm 24, as described, is preferably produced by co-extrusion
because adhesives used in co-extrusion are usually higher in molecular weight
than those
used in laminated composites, such higher molecular weight adhesives being
less
susceptible to being dissolved by aggressive printing inks.
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While Figs. 2 and 3 may create the impression that the diaphragm 24 has
substantial thickness, in practice, for a diaphragm 24 for a device 10 that is
designed to
contain 500 ml. of printing ink, a standard size, the diaphragm 10 will have a
total
thickness of the order of 5 mils (0.005 in.).
Although the best mode contemplated by the inventor for carrying out the
present invention as of the filing date hereof has been shown and described
herein, it will
be apparent to those skilled in the art that suitable modifications,
variations and
equivalents may be made without departing from the scope of the invention,
such scope
being limited solely by the terms of the following claims and the legal
equivalents
thereof.
What is claimed is:
