Method and apparatus for ink container locking

The present invention is an ink container for providing ink to an ink-jet printer. The ink container includes an inlet configured for connection to a pressurization source. The ink container also includes an expandable outer shell configured for expansion upon activation of the pressurization source. The expandable outer shell has an engagement feature that is configured for engagement with a corresponding engagement feature associated with the ink-jet printer. The expandable outer shell has an unexpanded position allowing removal of the ink container from the ink-jet printer and an expanded position wherein the outer shell engagement feature engages with the engagement feature associated with the ink-jet printer to resist removal of the ink container from the ink-jet printer.

BACKGROUND OF THE INVENTION 
The present invention relates to ink-jet printing systems, and more 
particularly, ink-jet printing systems which make use of ink containers 
that are replaceable separate from a printhead. 
Ink-jet printers frequently make use of an ink-jet printhead mounted to a 
carriage which is moved back and fourth across a print media, such as 
paper. As the printhead is moved across the print media, a control system 
activates the printhead to eject or jet ink droplets onto the print media 
to form images and text. 
Previously used printers have made use of an ink container that is 
separably replaceable from the printhead. When the ink cartridge is 
exhausted the ink cartridge is removed and replaced with a new ink 
container. The use of replaceable ink containers that are separate from 
the printhead allow users to replace the ink container without replacing 
the printhead. The printhead is then replaced at or near the end of 
printhead life and not when the ink container is exhausted. 
One type of replaceable ink container is disclosed in U.S. Pat. No. 
4,558,326 entitled "Purging System for Ink Jet Recording Apparatus" to 
Kimura et al. discloses the use of a replaceable ink cartridge having a 
hermetically sealed ink container bag disposed therein. The ink container 
bag in Kimura is in fluid communication with a recording head. Kimura 
makes use of the selective application of compressed air to the ink 
cartridge for pressurizing the ink container bag for forcing ink through 
the recording head thereby purging bubbles or solid matter from the ink 
flow path. When the purging of bubbles and solid matter is complete, the 
source of pressurized air is removed from the cartridge body and the 
cartridge body is vented to atmospheric pressure. After purging is 
complete, the recording apparatus in Kimura is operated with the source of 
pressurized air removed from the cartridge body. 
There is an ever present need for ink containment systems that are capable 
of providing ink at high flow rates to a printhead thereby allowing high 
throughput printing. This ink supply system should be cost effective to 
allow relatively low cost per page printing. In addition, the ink supply 
should be capable of providing ink at high flow rates in a reliable manner 
to the printhead. An interruption in the flow of ink to the printhead 
during operation of the printhead can result in excessive heating of the 
printhead. Operating the printhead without ink can result in catastrophic 
failure of the printhead or a reduction in printhead life. 
Additionally, these ink supplies should be capable of operating over a wide 
range of environmental conditions, such as atmospheric pressures and 
changes in atmospheric pressures. These ink supplies should also be 
transportable over a wide range of environmental conditions without 
effecting the integrity or reliability of the ink supply. For example, the 
ink supply should be capable of withstanding rapid changes in atmospheric 
pressure without a reduction in reliability or reduction in the integrity 
of the ink container. 
Finally, the ink supply should be easily replaceable as well as form 
reliable fluid connection with the printing device while minimizing or 
eliminating ink spillage which can reduce the reliability of the printing 
device. 
SUMMARY OF THE INVENTION 
The present invention is an ink container for providing ink to an ink-jet 
printer. The ink container includes an inlet configured for connection to 
a pressurization source. The ink container also includes an expandable 
outer shell configured for expansion upon activation of the pressurization 
source. The expandable outer shell has an engagement feature that is 
configured for engagement with a corresponding engagement feature 
associated with the ink-jet printer. The expandable outer shell has an 
unexpanded position allowing removal of the ink container from the ink-jet 
printer and an expanded position wherein the outer shell engagement 
feature engages with the engagement feature associated with the ink-jet 
printer to resist removal of the ink container from the ink-jet printer. 
In one preferred embodiment the engagement feature associated with the 
expandable outer shell is a raised portion on an outer surface of the 
expandable outer shell. In this preferred embodiment the engagement 
feature associated with the ink-jet printer is a recessed portion on the 
ink-jet printer. The expandable outer shell has an expanded position in 
which the raised portion extends into the recessed portion to resist 
removal of the ink container from the ink-jet printer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 depicts a schematic representation of a printing system 10 which 
includes the ink container 12 of the present invention. Also included in 
the printing device 10 is a printhead 14 and a pump 16. The pump 16 is 
connected by a conduit 18 for providing pressurized gas to the ink 
container 12. A marking fluid, such as ink 19, is provided by the ink 
container 12 to the printhead 14 by a conduit 20. This marking fluid is 
ejected from the printhead 14 to accomplish printing. 
The ink container 12 which is the subject of the present invention includes 
a fluid reservoir 22 for containing ink 19, an outer shell 24, and a 
sealing portion or cap 26. In the preferred embodiment the cap 26 includes 
a gas interconnect 28 configured for connection to conduit 18 for 
pressurizing the outer shell 24 with gas. A fluid interconnect 30 is also 
included in the cap 26. The fluid interconnect 30 is configured for 
connection to the conduit 20 for providing a fluid connection between the 
fluid reservoir 22 and fluid conduit 20. 
In the preferred embodiment the fluid reservoir 22 is formed from a 
flexible material such that pressurization of the outer shell produces a 
pressurized flow of ink from the fluid reservoir 22 through the conduit 20 
to the printhead 14. The use of a pressurized source of ink in the fluid 
reservoir 22 allows for a relatively high fluid flow rates from the fluid 
reservoir 22 to the printhead 14. The use of high flow rates or high rates 
of ink delivery to the printhead make it possible for high throughput 
printing by the printing system 10. 
FIG. 2 depicts one embodiment of the printing system 10 shown in 
perspective. The printing system 10 includes a printing housing or printer 
chassis 32 containing one or more ink containers 12 of the present 
invention. The embodiment shown in FIG. 2 is shown having four similar ink 
containers 12. In this embodiment, each ink container contains a different 
ink color. Therefore, four color printing is accomplished by providing 
cyan, yellow, magenta and black ink from the four ink containers 12 to one 
or more printheads 14. Also included in the printer chassis 32 is a 
control panel 34 for controlling operation of the printer 10 and a media 
slot 36 from which print media such as paper is ejected. 
As ink 19 in each ink container 12 is exhausted the ink container 12 is 
replaced with a new ink container 12 containing a supply of ink. In 
addition the ink container 12 may be removed from the printer chassis 32 
for reasons other than an out of ink condition such as changing inks for 
an application requiring different ink properties or for use on different 
media. It is important that the ink container 12 is not removed during 
certain events such as when the printer is operating or when the ink 
container 12 is pressurized. Removal of the ink container 12 during 
operation of the printing system 10 can result in improper cooling of the 
printhead. Thermal printheads often require ink flow through the printhead 
during printing to maintain printhead temperatures within an operating 
temperature range. If the flow of ink 19 through the printhead is 
interrupted by the removal of the ink container 12, then the proper 
operating range may not be achievable resulting in overheating of the 
printhead. This overheating, if sufficient, can result in catastrophic 
failure of the printhead. 
In the case of pressurized ink delivery systems such as show in FIG. 1 it 
is important that the ink container 12 not be removed from the printer 
chassis 32 when the container is pressurized. Removal of a pressurized ink 
container 12 can result in ink splattering or spilling from the fluid 
interconnect 30. Ink spillage is objectionable not only for the operator 
of the printer who must handle the spattered ink container 12 but also 
from a printer reliability standpoint. Inks used in ink-jet printing 
frequently contain chemicals such as surfactants which if exposed to 
printer components can effect the reliability of these printer components. 
Therefore, ink spillage inside the printer can reduce the reliability of 
printer components thereby reducing the reliability of the printer. 
The present invention, as will be described with respect to the embodiments 
shown in FIGS. 3A and 3B and 4A and 4B, is directed to a locking method 
and apparatus for selectively preventing or resisting the removal of the 
ink container 12 from the printer housing or chassis 32. By selectively 
preventing the removal of the ink container 12 problems such as operation 
of the printhead without ink and ink spilling or splattering, to name a 
few, can be reduced or eliminated. 
FIGS. 3A and 3B depict an ink container 12 of the present invention which 
includes locking features of the present invention for selectively 
resisting or preventing removal of the ink container 12 from the printer 
chassis 32. Because both ink containers are similar, except for the color 
of ink contained within their respective fluid reservoir, the same 
reference numbering will be used for each ink container 12. The ink 
containers 12 include an outer shell 24 having an outer surface thereon. 
Also included on each ink container 12 is an air interconnect 28 and a 
fluid interconnect 30 (not shown) which are configured for connection to a 
corresponding air and fluid interconnects 34 and 36, respectively 
associated with the printer chassis 32. With the ink container 12 properly 
inserted into the printer chassis 32 the air interconnect 28 and fluid 
interconnect 30 associated with the ink container 12 engage with 
corresponding fluid and air interconnects 34 and 36, respectively, 
associated with the printer chassis 32. Proper insertion of the ink 
container 12 into the printer chassis 32 establishes communication between 
the printhead 14 and the fluid reservoir 22 and establishes communication 
between the inner portion of outer shell 24 and the pump 16. 
An important feature of the present invention is an engagement feature or 
raised portion 38 shown on the outer surface of outer shell 24. In the 
preferred embodiment the raised portion 38 is positioned on opposite sides 
of the outer shell 24 of ink container 12. With the ink container 12 
properly inserted into the printer chassis 32 sidewalls 40 associated with 
the printer chassis 32 have a corresponding engagement feature 42. In one 
preferred embodiment the engagement feature 42 is a depression or recessed 
portion which is properly aligned with the raised portion 38 on the ink 
container 12. 
FIGS. 4A and 4B represent a sectional view taken through lines 4-4' which 
passes through the raised portion 38 to better show the alignment of 
raised portions 38 and depressions or recessed portions 42. It can be seen 
from FIG. 4A that the walls 40 on either side of the ink container 12 are 
spaced to provide sufficient tolerance for insertion and removal of the 
ink container 12 from the printer chassis 32. Therefore, when an ink 
container 12 is either empty or an ink change is required the ink 
container 12 can be removed from the printer chassis 32 and a new ink 
container 12 inserted. 
FIG. 4B shows the ink container 12 with the outer shell 24 represented by 
dotted lines in an expanded position. The outer shell 24 of ink container 
12 is expanded by providing pressurized gas from pump 16 to the ink 
container 12. This pressurized gas produces an expansion of the ink 
container 12. Upon expansion of the ink container 12 the outer shell 24 
expands or is displaced furthest at the weakest structural portion of the 
ink container 12. Placement of the raised portion 38 at or near the 
weakest structural portion maximizes the displacement of the raised 
portion 38. This arrangement allows for effective interlocking between the 
raised portion 38 and the recessed portion 42 in the pressurized state 
while maximizing the distance between the raised potion 38 and the 
recessed portion 42 in the non-pressurized state. This in turn provides 
for maximum tolerance between the ink container 12 and the printer chassis 
32. Maximizing this tolerance reduces the manufacturing costs of both the 
ink container 12 and the printer chassis 32. 
The ink container 12 is pressurized by pump 16 to expand the ink container 
12 to lock the ink container 12 within the printer chassis 32. One example 
of the use of this expansion lock of the present invention is during the 
printing operation to prevent removal of the ink container 12 which can 
result in printhead damage. For the ink supply system shown in FIG. 1 the 
pressurization of the ink container 12 in addition to expanding the walls 
of the ink container 12 to prevent removal of the ink container 12 also 
pressurizes the fluid reservoir 22 for providing a pressurized ink supply 
to the printhead 14. 
It is important that during the printing operation the ink container 12 is 
not removed from the printer chassis 32. Removal of the ink container 12 
during the printing operation may result in activation of the printhead 
without a supply of ink within the printhead sometimes referred to as "dry 
firing". Operation of the printhead without a proper supply of ink can 
result in a catastrophic failure of the printhead, or reduction in 
printhead life or a reduction in reliability of the printhead. 
In addition, removal of the ink container 12 from the printer while the 
printer is in operation could result in the removal of a pressurized ink 
container. This ink container when left in a pressurized state for a long 
period of time without any structural support such as that provided by 
walls 40 of the printer chassis 32 may result in damage to the ink 
container 12. Pressurization of the ink container 12 over an extended 
period of time can result in the permanent deformation of the ink 
container 12. For this reason, it is desirable that the removal of the ink 
containers 12 from the printer chassis 32 be resisted or prevented when 
pressurized. 
The present invention requires only that the ink container 12 which expands 
when pressurized and that the expanded outer surface 24 engage the walls 
40 within the printer chassis 32. It is the friction of the outer surface 
24 and the walls 40 which prevent or resist removal of the ink container 
12 in the expanded position. To provide greater removal resistance raised 
portions 38 can be provided on the ink container outer surface 24 as well 
as corresponding recesses 42 in the inner walls 42 of the printer chassis 
32. It is the engagement of the raised portions 38 associated with the ink 
container 12 and the recessed portions 42 associated with the printer 
chassis 32 that provided added resistance to prevent or resist the removal 
of the ink container 12 when pressurized. 
The amount of resistance to removal of the ink container 12 from the 
printer chassis 32 depends on the stiffness of the outer shell 24, the 
orientation of the engagement portion relative to the direction of removal 
and the area of engagement between the raised portion 38 and the recessed 
portion 42 associated with the printer chassis 32. In the preferred 
embodiment the outer shell 24 is made from high-density polyethylene 
(HDPE) the thickness of the walls of the outer shell as well as the 
dimensions of the ink container 12 will effect the degree of outer shell 
expansion. In addition, extending the raised portion 38 along the outer 
shell 24 of the ink container 12 or using a larger number of raised 
portions 38 on the ink container 12 together with corresponding recessed 
portions 42 can be used to increase the resistance to removal of the ink 
container 12 from the printer chassis 32. For example, a series or pattern 
of ridges or bumps can be formed on the ink container 12 to define the 
engagement feature 38. These patterns of ridges or bumps interlock with 
corresponding patterns of ridges or bumps forming the engagement features 
42 associated with the printer to resist or prevent removal of the 
pressurized ink container 12. 
While the preferred embodiment of the present invention has been described 
as having raised portions that define the engagement portion 38 on the ink 
container 12 which selectively engage with depressions or slots that 
define the engagement portion 42 on the printer 32, this arrangement of 
engagement portions 38 and 42 can be swapped. For example, the engagement 
portion 38 on the ink container 12 can be a depression, slot or pattern of 
depressions which engage with a raised portion, raised ridge or a pattern 
of raised portions which define the engagement portion 42 associated with 
the printer 32. 
The present invention provides an elegant solution for selectively 
preventing the removal of ink containers. This solution is economical as 
well as highly reliable.