One very popular type of printing device is the inkjet printer. Some inkjet printers use a replaceable fluid container to supply ink and/or other fluids to a fluid ejection mechanism to print onto a medium. The fluid container and fluid ejection mechanism are sometimes integrated together into a single replaceable unit that may be referred to as a pen or print cartridge. The fluid ejection mechanism may include, for example, a printhead that selectively deposits ink or other fluids onto a print medium, such as paper, through an array of nozzles. Such fluid ejection may be initiated in the printhead, for example, using thermal or piezoelectric action.
A fluid container may include one or more internal chambers that act as reservoirs for one or more fluids. A fluid holding member may be arranged within a chamber to hold the fluid in a manner that allows it to be selectively ejected through the printhead. The fluid holding member provides a backpressure that usually prevents the fluid from simply draining or drooling out of the printhead nozzles. By way of example, certain fluid holding members include fluid-absorbing foam material.
Fluid stored in the fluid holding member may be provided to the printhead through a fluid conduit. The fluid conduit, which may be referred to as a standpipe, extends into the chamber and provides an opening that contacts a surface of the fluid holding member. The fluid conduit may also include a filter or screen in contact with the fluid holding member.
The fluid container may also include an air vent that allows air pressure within a chamber to equalize or otherwise adjust with the external atmosphere's pressure. Such an air vent also allows for additional air to enter into the chamber during printing as the fluid therein is consumed through ejection.
Air or other gas that is trapped or otherwise held inside the fluid container may affect the operation of the fluid container as the pressure of the trapped air changes. For example, in certain print cartridges increased pressure of trapped air may affect the backpressure provided by the fluid holding member such that fluid may leak or drool out of the printhead.
The accompanying drawings illustrate various embodiments of the present invention and are a part of the specification. The illustrated embodiments are merely examples of the present invention and do not limit the scope of the invention.
The illustrative drawings shown and described herein are simplified depictions (not to scale) showing some of the features that may be provided in a fluid container for a printing device. These simplified drawings are not intended to limit the applicability or scope of the appended claims to more or less complex fluid containers.
Fluid holding member 106 may include, for example, one or more materials and/or parts that accept, hold, and release fluid(s) as desired for proper operation. In certain implementations, fluid holding member 106 includes foam or the like providing a controlled capillary force. Such materials and arrangements are well known, for example, see U.S. Pat. No. 4,771,295 issued to Baker et al. In this example a lid 108 is provided to further define chamber 104 when attached to housing 102. Here, an air vent 110 extends through lid 108. While not shown, air vent 110 may take a serpentine route (e.g., a labyrinth path), as is well known.
A fluid conduit 112 extends inwardly into chamber 104. While not necessary, in this example, fluid conduit 112 is at least partially integrally formed with housing 102. Fluid conduit 112 includes a fluid opening 114 through which fluid in fluid holding member 106 may be drawn during printing. Here, a screen or filter 116 is also shown as being arranged over or otherwise covering fluid opening 114. Filter 116 tends to prevent debris and/or air from entering fluid conduit 112. Filter 116 may also act to keep a fluid flow path through fluid conduit 112 clear by preventing intrusion of fluid holding member 106 into the fluid conduit 112.
Fluid that is drawn from fluid holding member 106, through filter 116 (if present), enters into fluid conduit 112 and is supplied to a fluid ejection mechanism 118. Fluid ejection mechanism 118, in this example, includes a printhead 118 having a plurality of nozzles 120. Those skilled in the art will recognize that fluid ejection mechanism 118 may include other components (not shown) such as circuitry, interconnects, other fluid chambers, channels, conduits, etc.
The fluid in fluid conduit 112 may be held at less than atmospheric pressure to prevent the fluid from drooling out nozzles 120. As is well understood, this negative relative pressure, or backpressure, must not be so great that air is pulled into the interior of fluid ejection mechanism 118 (e.g., firing chambers (not shown) associated with the nozzles), thereby emptying them of ink and causing them to no longer function when needed.
Various systems have been devised to provide the appropriate backpressure. One reliable such system uses a fluid holding member 106, which may include, for example, a porous material, such as synthetic foam, to provide backpressure by capillary action. In other implementations, fluid holding member 106 may include other types of capillary force providing structures such as, for example, a body of bonded polyester fibers or the like.
While this example is drawn to a print cartridge that will be used on-axis, the various methods and apparatuses provided herein are clearly adaptable to off-axis printing devices, and to other non-printing fluid storage and/or fluid delivery devices or the like.
Fluid holding member 106 contacts filter 116 as illustrated by the compressed and bulging protrusions above air pocket 122. For illustrative purposes, an air space 136 is shown within chamber 104 between fluid holding member 106 and lid 108. Air space 136 may be optional and formed or otherwise maintained by protrusions or the like (not shown) associated with lid 108, housing 102 and/or fluid holding member 106. Air within air space 136 is fluidically coupled via air vent 108 to atmosphere 134, which is located external to container 100.
As illustrated in this example, at least one air pocket 122 is defined within chamber 104 below fluid holding member 106 and between an interior surface 132 (see
Fluid holding member 106 may, for example, be arranged such that there is some compression with fluid conduit 112 and/or filter 116. This is illustrated in the drawings by the slight bulging of fluid holding member 106 about filter 116 and above air pocket 122. Such compression is known to increase the capillarity provided by fluid holding member 106 in a region nearby or otherwise adjacent to filter 116.
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As used herein the term non-wetted is not necessarily meant to require a certain level of dryness. Instead, the term “non-wetted” is intended to differentiate between two states that regions or portions of fluid holding member 106 may be in based on the presence or the lack of extractable levels of fluid. Thus, for example, while a fluid holding member may contain some type of fluid everywhere or nearly everywhere the “wetted” portion will include enough fluid to allow some fluid to be drawn through the fluid conduit for printing or the like as intended by design. Conversely, the “non-wetted” portions will not include enough fluid to allow some fluid to be drawn through the fluid conduit for printing or the like as intended by design. A wetted portion may therefore overtime become a non-wetted portion as a result of the fluid being drawn from it.
Another notable distinction is that, comparing equal volumes of the fluid holding member, a non-wetted portion will be more permeable to air than the wetted portion since at least some of the internal pathways through the wetted portion will contain fluid.
As illustrated in the example of
The unwanted pressure may be caused by pressure differences between air pocket 122 and atmosphere 134. For example, changes in altitude during shipping may cause the air pressure of atmosphere 134 to be significantly lower than the air pressure of the air within air pocket 122. In another example, changes in temperature of the air within air pocket 122 may result in a pressure difference. While in these two examples the pressure difference occurs because the air pressure of the air within air pocket 122 is higher than the atmospheric air pressure, it is recognized that the pressure difference may occur because the air within air pocket 122 is lower than the atmospheric air pressure. However it occurs, such a pressure difference may cause fluid 124 to drool or otherwise leak out of nozzles 120.
Thus, in accordance with certain aspects of the present invention, one or more novel features are provided to reduce restriction of air flowing between vent 110 and air pocket 122.
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The preceding description has been presented only to illustrate and describe embodiments of the invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. Many modifications and variations are possible in light of the above teaching.
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Number | Date | Country | |
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20070008389 A1 | Jan 2007 | US |