WO1997016314A1

WO1997016314A1 - Ink cartridge with improved volumetric efficiency

Info

Publication number: WO1997016314A1
Application number: PCT/US1996/017341
Authority: WO
Inventors: James D. Story
Original assignee: Jetfill, Inc.
Priority date: 1995-11-03
Filing date: 1996-11-01
Publication date: 1997-05-09
Also published as: EP0868307A1; AU7526096A; CA2236599A1

Abstract

A cartridge for delivering and containing ink contains an ink retention cavity (16), a first zone (14) adjacent to the ink retention zone (16) with a means (13) for introducing the liquid ink from the ink retention cavity (16) into the first zone (14), a second zone (12) being extended from the first zone (14) and an egress port (18). The degree of capillarity in the first zone (14) is greater than the degree of capillarity in the second zone (12). The degree of capillarity in the second zone (12) is greater than that in the ink retention cavity (16). The first and second zones contain a vacuum-producing material. Since the cartridge of the invention uses capillarity in the regulation of the flow of the ink, it can be used at any orientation without leakage.

Description

INK CARTRIDGE WITH IMPROVED VOLUMETRIC EFFICIENCY

SPECIFICATION Field of the Invention

The present invention relates to an ink jet cartridge with improved ink capacity and containment. Background of the Invention Ink jet cartridges such as those used in ink jet printers, facsimiles, postal meters and other recording devices are generally well known in the art. Such cartridges comprise an ink reservoir for supplying ink. The ink is supplied to a printhead through a series of microchannels, where the ink is heated, charged, or pumped causing it to be expelled through the printhead onto a recording sheet.

Ink cartridges are commonly comprised of a cavity which may be partially or entirely filled with foam. Foam commonly serves as an ink retention device, preventing ink from freely flowing out of a cartridge because of gravity or changes in ambient temperature or pressure. In order to be commercially viable, ink jet cartridges need to fulfill three objectives: (1) the ability to supply a large amount of ink within a Iimited amount of space; (2) means to prevent ink from oozing out of the cartridge; and (3) means to prevent the creation of a vacuum within the cartridge. The latter, in particular, causes the flowability of ink supply to decrease despite the presence of ink within the cartridge.

The ink jet cartridge configurations of the prior art having ink containment areas have limitations making them commercially unattractive. For instance, U.S. Patent No. 5,430,471 discloses a multi-zoned ink cartridge wherein the zones are connected in series by a liquid supply material. During operation, ink oozes out of the liquid supply port of the cartridge. This typically occurs when the liquid supply material becomes saturated. Such saturation is normally attributed to positive pressure caused by either a temperature or altitude increase.

European Patent Application No. 0 639461 A2 further describes a cartridge using capillary action and gravity for ink containment. When inverted, ink migrates from the liquid supply gap connecting the ink cavity and the vacuum material section. The cartridge contains a groove to prevent ink leakage when the cartridge is inverted. This cartridge's reliance on gravity further reduces the orientations in which the cartridge can effectively operate. U.S. Patent No. 5,509,140 discloses an ink cartridge for use with a bubble jet printer which is composed of two zones. The zones, which are separated by a partition, communicate with each other through an opening at the bottom wall of the partition. The zone closest to the opening has an air vent and is in contact with the ink jet recording head and contains a sponge- like material for producing a negative pressure. The second zone, sealed from ambient air except through the opening at the bottom wall of the partition, contains the ink. The partition further has a groove for forming an air flow passage from the second to the first zones. Under operation, the internal pressure of the cartridge decreases as a result of the pressure difference between the second zone and the first zone. Air is introduced into the first zone through the air vent which proceeds into the second zone. This alleviates the pressure differential. In the process, ink leaks from the second zone.

U.S. Patent No. 5,453,771 discloses another ink cartridge for an ink jet printer. This cartridge contains an ink cavity and an adjustment room containing compressed fibers. The densities of the fibers increase towards the feed passageway into the ink jet head. A longitudinal bulkhead separates the ink cavity and the adjustment room. A connection opening at the lower part of the bulkhead bridges the adjustment room with ink cavity. An ink egress port is connected posteriorly to the adjustment room. Due to the constant path of travel of ink and air between the adjustment room and ink cavity, such ink cartridges cannot be shipped opened. In addition, ink characteristically leaks from such cartridges in shipment.

Other cartridges known in the art use springbags, which require them to be regularly shaped in order to provide spring action to drive two parallel plates apart. The resulting underpressure which is produced prevents ink leakage during operation. In addition, the reservoir holding capacity of such cartridges is diminished in light of their inability to make use of irregular or small spaces. Springbag cartridges further require a multitude of high-precision parts including plates, springs, flexible bags, housings, and sealing or connection members. Such dissimilar materials further need to be sealed.

Other cartridges of the prior art are characterized by a bubble generator for supplying underpressure. Such bubble generators rely on gravity and require an adequate amount of surface tension. The ink supply is kept in contact with the bubble generator in order to generate the requisite surface tension to sustain the under pressure. The number of orientations in which such cartridges can be used is therefore Iimited. Brief Description of the Drawings

FIG. I is a front exterior view of an ink jet cartridge defined by the invention.

FIG. II is an exploded view of a disassembled ink jet cartridge of the invention.

FIG. Ill is a frontal exterior view of an embodiment of the ink jet cartridge of the invention. FIG. IV is a lateral view of the invention demonstrating the use of a transfer wicking material within the ink receptacle.

FIG. V is an exploded view of a disassembled ink jet cartridge defined by the invention. Summary of Invention An improved system for delivering and containing ink, readily adaptable to irregular geometric shapes, comprises a cartridge containing an ink receptable, an egress port, an ink flow regulating zone and ink overflow zone. In operation, the ink flow regulating zone has a higher degree of capillarity than the ink overflow zone. At least a portion of the ink flow regulating zone is located adjacent to the ink receptacle, ink ingress ports connect the ink receptacle and the ink flow regulating zone. The ink overflow zone, partitioned from the ink receptacle, may laterally extend from the ink flow regulating zone. The ink overflow zone further contains an air vent. The cartridge is typically composed of plastic and manufactured using conventional injection molding processes known in the art. The ink flow regulating zone and the ink overflow zone further contain a vacuum-producing material. These zones regulate the sequential emptying and filling of ink via capillary action into the cartridge. Since the cartridge of the invention uses capillarity in the regulation of the flow of the ink, it can be used at any orientation without leakage. Description of the Preferred Embodiments

The cartridge of the invention is used with an ink jet recording apparatus. It is capable of supplying the requisite amount of ink to the recording head during the recording operation. The cartridge is of the exchangeable type and can be easily mounted or demounted relative to the recording apparatus without ink leakage. Alternatively, the cartridge may be the non-exchangeable type, permanently affixed to the recording apparatus. The cartridge further will not leak in transit.

Referring now to FIG. I, the cartridge of the invention 10 consists of an ink receptacle 16 for storing ink, an ink flow regulating zone 14, an ink overflow zone 12 and an ink egress port 18. Ink flow regulating zone 14, in intimate contact with ink egress port 18, controls the flow of ink into the egress port. Ink egress port 18 connects to the ink jet recording head. At least a portion of ink flow regulating zone 14 is contiguous with ink receptacle 16. The ink flow regulating zone typically does not contain an air vent. Boundary wall 11 represents the juncture between ink flow regulating zone 14 and ink receptacle 16 as well as ink receptacle 16 and ink overflow zone 12. Boundary wall 11a between ink receptacle 16 and ink flow regulating zone 14 contains one or more openings 13 dividing the ink receptacle from the zones of capillarity. (As used herein, the term "capillarity" shall refer to the ink affinity of a given zone and its ability to use capillary action to draw or release ink to other zones or zones of the cartridge.) At openings 13, ink receptacle 16 is in intimate contact with ink flow regulating zone 14.

Ink flow regulating zone 14 is flush against boundary wall 11a. In such intimate contact, ink flows through opening(s) 13 into the ink flow regulating zone 14 from ink receptacle 16.

The conduit or passageway created by openings 13 typically are in the form of slits, holes or some variation thereof. Its geometry is not critical although in the present invention, multiple small diameter round holes are normally employed. Openings 13 permit the flow of ink from ink receptacle 16 into ink flow regulating zone 14.

Ink overflow zone 12 is connected to ink flow regulating zone 14. The capillarity affinity of ink overflow zone 12 is less than that of ink flow regulating zone 14, yet higher than that of ink receptacle 16. Ink flow regulating zone 14 and ink overflow zone 12 are composed of a vacuum producing material. Differences in capillarity between these zones may be created by selection of the vacuum producing material.

During operation, the compressed area, defined by the vacuum producing material, created at boundary wall 11a creates a localized area of high capillary forces or "wicking." This eliminates ink diffusion from ink flow regulating zone 14 to ink overflow zone 12, thereby maximizing the area available to accommodate ink which may be displaced from the ink receptacle if a relative positive pressure condition were to exist.

Ink overflow zone 12 functions as a wick, passively drawing ink which overflows from ink flow regulating zone 14. As a result, ink is prevented from drooling out of the ink egress port. Because of the affinity for ink of ink flow regulating zone 14 relative to ink receptacle 16 the ink flow regulating zone can be placed higher than the printhead or in any other orientation within the cartridge without regard to gravity. In light of the flexibility allowed in the placement of the ink flow regulating zone within the cartridge, a wide variety of cost efficient configurations for the cartridge are possible while increasing volumetric efficiency, reliability and the operating environment of the cartridge.

Under normal operations of the ink jet recording apparatus, the ink is ejected through the orifice of the ink jet recording head thereby producing suction in the cartridge. Ink exits the cartridge through the ink egress port 18. As air in ink receptacle 16 contracts and expands in reaction to the fluctuations in temperature and pressure, an equal amount of ink will be displaced from ink receptacle 16 into ink flow regulating zone 14 through openings 13. The amount of displaced ink can be determined by Boyle's ideal gas law (PV=nRT). The internal pressure of ink receptacle 16 decreases as a result of the pressure difference between ink receptacle 16 and ink flow regulating zone 14. With the continued recording operation, this pressure difference continues to increase.

Ink overflow zone 12 further contains air vent 17 for maintaining ambient pressure, thereby preventing either a vacuum or ink expulsion from the cartridge. Air is introduced into the cartridge through air vent 17 in the ink overflow zone. Ink receptacle 16 is maintained at a slight under pressure. This under pressure prevents the leakage of ink from the cartridge. During the ink jet recording operation, the above process is repeated, so that substantially a constant vacuum is maintained in the cartridge.

Surplusage of ink entering ink flow regulating zone 14 passes into ink overflow zone 12. The ink overflow zone is partitioned by side boundary wall 11b and longitudinal boundary wall 11c from ink receptacle 16. No openings are located within either boundary walls 11b or 11c. Ink therefore is incapable from flowing directly from ink receptacle 16 into ink overflow zone

12. Since the capillarity of ink flow regulating zone 14 is greater than the capillarity of ink overflow zone 12, after becoming normalized, ink migrates from ink overflow zone 12 to ink flow regulating zone 14 back into ink receptacle 16 until the ink overflow zone is emptied. If, however, ink flow regulating zone 14 is saturated or becomes oversaturated, ink overflow zone

12 will accept the overflow, thereby preventing the ink from drooling out of the cartridge through the ink egress port. Because the ink flow regulating zone can be effectively completely drained of ink without causing starving of the printhead, its ability to accept ink during environmental fluctuations, such as variations in temperature or altitude, is increased.

Once filled with ink, the cartridge of the invention is capable of maintaining a nearly constant back pressure during periods of environmental fluctuation. This is principally attributed to the fact that ink flow regulating zone 14 is always saturated and ink overflow zone 12 acts only as an overflow zone to accommodate the ink which has moved from ink receptacle

16. Further, since all of the ink is first used from the vacuum-producing material and lastly from the ink in ink receptacle 16, it is normally easier and more accurate to determine the actual ink level.

Ink receptacle 16 has the highest ink capacity of any of the zones of the cartridge since its volume is not occupied by any material. An advantage of the present invention therefore is the ability of the ink receptacle to occupy a greater percentage of the cartridge as compared to the cartridges of the prior art. This allows more ink to be contained within the same unit of volume. Essentially, ink receptacle 16 is the only part of the cartridge of the invention which is dependent on gravity; ink being gravitationally fed to ink flow regulating zone 14.

Ink receptacle 16 of the invention further has an efficiency value approaching 100% since it can deliver relatively all the ink it contains through the openings in boundary wall 11a. In another embodiment of the invention, a third zone of different capitta ly is defined by a vacuum producing material located at the point of connection of the cartridge with the printer. This third zone has a capillarity which is higher than the capillarity of ink flow regulating zone 14. The vacuum producing material of this third zone is selected to render the desired degree of capillarity. In operation, the vacuum producing material of this third zone couples itself to the vacuum producing material of the ink flow regulating zone during the compression stage.

The ink flow regulating zone is in intimate contact with the third zone without means for the passage of ambient air. As a result, ink and air exchange may be precisely regulated. The vacuum producing material in the ink overflow zone and the ink flow regulating zone may be any known material capable of accommodating the fluid displaced by the expansion which occurs in the ink receptacle. Vacuum materials characterized by relatively high void volumes, such as foam-like or sponge-like materials made of fibers and porous materials having continuous pores, are preferred since it is easy to adjust the vacuum and the ink retaining power with such materials. Such materials include polyether foams, polyester foams, polyurethane foams and sponges, felt and porous plastic. Typically, the vacuum producing materials for use in these zones have as high as 97% or more void volumes. In a particularly preferred embodiment, the vacuum-producing material is a polyether reticulated foam. Alternatively, the vacuum producing material may be glass beads as well as sand or polyamides such as nylon -6,6.

The vacuum producing material may be the same or a different absorbent material in the ink overflow zone and the ink flow regulating zone. Varying degrees of absorbency of the vacuum producing material may be obtained by compressing the material or by treating it to provide different capillarity action. Increasing the amount of compression provides for increased capillarity.

In a most preferred embodiment, the vacuum producing material is a foam or sponge having between about 60 to about 110 ppi (pores per inch).

It may further be characterized by a felting firmness factor of between 1 to about 5. The firmness factor is dependent on such physical properties of the ink formulation as surface tension and viscosity. Generally, a smaller pore size (or higher ppi) provides for greater capillarity as does an increased compression of the absorbent material. Since such vacuum-producing materials have a large surface area, some of the displaced ink may not be extracted, thereby reducing ink delivery efficiency of the cartridge. It is therefore desirable to minimize the size of the ink flow regulating zone. In particular, it is desirable to minimize the size of the ink flow regulating zone as well as the ink overflow zone and maximize the size of the ink receptacle.

FIG. II is an exploded view of the disassembled ink jet cartridge of the invention and represents another embodiment wherein the cartridge contains three distinct zones of differing capillarity. Central body 1 of the ink cartridge contains ink receptacle 16, ink overflow zone 12 and ink flow regulating zone 14. Vacuum producing material 27, preferably a prefabricated block of absorbent material, is inserted into both ink overflow zone 12 and ink flow regulating zone 14. The vacuum producing material for these zones, which may be a unitary piece or separate pieces of material, have varying absorbency for retaining the recording ink. The compressibility of the vacuum producing material in each of these zones is nevertheless different. The vacuum producing material is generally more highly compressed within ink flow regulating zone 14. This provides for greater capillarity in this zone than in ink overflow zone 12.

Openings 13 in boundary plate 11a serve as conduits for the liquid ink. There are no corresponding openings in boundary plate 11b which separates ink receptacle 16 from ink overflow zone 12, as does boundary plate 11c.

An air vent 22a extends to the outside at port 26 of cap 24. The vent empties into ink overflow zone 12. The vent surrounded by vent passageway 22b which extends through ink receptacle 16 and shields it from air seepage. Cap 24 further includes priming dome 28 on its exterior wall for manually priming the cartridge. The priming dome is composed of a flexible or resilient material and, when depressed by the user, decreases the volume of ink within ink receptacle 16. The ink is thus forced into ink flow regulating zone 14. Priming may be further enhanced if dome 28 is actuated with vent plug 25 installed in air vent 26 and 22a. When dome 28 is actuated, a positive pressure is developed which forces ink from egress port 34 into the printhead.

Cap 24 further contains ink supply port 21 for filling the initial ink formulation into the cartridge. Fill hole plug 23, typically a glass or metal bead or plastic ball, is inserted into ink supply port 21. The cartridge may further be optionally sealed with air vent cap 25 which is lodged over outside air port 26 and air vent 22a. This provides for greater protection against pressure or air passage during storage and transit. At the time of usage, it is preferred to remove air vent cap 25 to relieve pressure. Plug 29 is then removed.

The cartridge of the invention may further comprise endcap 30 which fits underneath the area defined by ink overflow zone 12 and ink flow regulating zone 14. Endcap 30 contains elevated riser 32. The endcap fits on the bottom of central body 1. Elevated disk 32 contains egress channel

34; the bottommost portion of which serves as the egress port which connects to the ink jet printer and supplies the ink to the printhead. Anterior to egress port 34 is egress zone 36 which is in direct contact with ink flow regulating zone 14. In another embodiment of the invention, ink overflow zone 12 is in contact with both egress zone 36 and ink flow regulating zone 14. In operation, drooling within the egress zone causes the ink to flow to the ink overflow zone. When normalized, the ink would then flow to the ink flow regulating zone. The flow of ink within such a cartridge proceeds from the zone of lowest capillarity to the zone of highest capillarity.

Egress zone 36 is composed of a material capable of rendering a capillarity greater than the capillarity of ink flow regulating zone 14. In a most preferred embodiment, egress zone 36 is comprised of a porous material, such as a porous plastic, like "tip mix" available from Porex Technologies located in Fairburn, Georgia. In an alternative embodiment, a fine wire mesh or a material such as Goretex™ may be employed.

Thus, the cartridge of FIG. II contains three zones, each of which is characterized by a distinctive capillarity. Ink overflow zone 12 has the lowest capillarity. Egress zone 36 has the highest capillarity. Ink flow regulating zone 14 has a capillarity intermediate between the capillarity of the ink storage zone and the egress zone. Distinction is capillarity in ink overflow zone 12 and ink flow regulating zone 14 may be obtained by use of vacuum- producing materials of varying density. Altematively, vacuum-producing materials of equal density may be used in the zones. In this case, local compression exerted during operation of the cartridge on ink flow regulating zone 14 will render higher capillarity than that exhibited in ink overflow zone

12.

The bottommost portion of egress zone 36 preferably contains projecting ring 38 onto which egress zone 36 is retained. An O-ring seal is preferably provided within ring 38 to ensure a fluid tight connection between the egress zone and the printhead of the ink jet cartridge.

Ink flow regulating zone 14 is in intimate contact with egress zone 36 and is instrumental in the transfer of ink into the zone of higher capillarity, egress zone 36. The absence of air vents facilitates regulation of ink and air exchange. When compressed by the printhead, the high capillary force within egress zone 36 causes ink to be ejected into the printhead. The necessity of priming is thereby markedly reduced, if not eliminated. The priming efficiency of the ink jet cartridge is further increased (without having to rely on priming dome 28) in light of the localized compression of ink flow regulating zone 14.

As illustrated in FIG. II, the area of ink receptacle 16 may be from 1 to 5 times the area of the overflow zone 12. The diameter of the pores of the vacuum-producing material in ink flow regulating zone 14 and ink overflow zone 12 typically is around 50 and 100 μ, respectively. The size of the porous disk comprising the zone of highest capillarity is typically around 8 μ. FIG. Ill presents a lateral exterior view of the embodiment set forth in

FIG. II. The cartridge preferably contains a means for the user to grip cap 24 to facilitate removal of the cartridge from the housing. Illustrated are a series of raised ridges 38 on the side surface of the cartridge.

The cartridge, easily manufactured using conventional injection molding processes, is typically composed of plastic such as polystyrene, acrylonitrile butadiene styrene resin, styrene acrylonitrile resin, high density polyethylene and polypropylene as well as commercially available plastics such as K-resin. In a most preferred embodiment, the cartridge is made of transparent plastic in order to allow the user to readily determine the amount of ink remaining in the cartridge. Cap 24 and endcap 30 are secured to the central body of the cartridge by ultrasonic welding such as by those techniques conventionally used for far field welding and near field welding.

Ink flow regulating zone 14 is adjacent to and connects with ink receptacle 16 as well as ink overflow 12. Only ink flow regulating zone 14 is contagious with ink overflow zone 12. Ink flow regulating zone 14 is further contagious with the zone of highest capillarity, when present, whether as egress zone 36, as illustrated in FIG. II, or as the zone defined by the point of connection of the cartridge with the printer.

To prevent ink starving, the zone of highest capillarity needs to be the last zone which becomes empty of ink. Thus, when the ink jet cartridge contains the three zones illustrated in FIG. II, egress zone 36 becomes void of ink only when ink overflow zone 12 and ink flow regulating zone 14 are depleted of ink.

When the ink jet cartridge of the invention has a third zone of different capillarity defined by a vacuum producing material located at the point of connection of the cartridge with the printer, this zone becomes void of ink only when the other two zones - ink overflow zone 12 and ink flow regulating zone 14 - become depleted of ink.

The zone of highest capillarity further exhibits the highest ink affinity as well as the lowest ink holding efficiency of any of the zones of the ink cartridge of the invention. The zone of highest capillarity further has high ink transferability.

When the cartridge is subjected to an increase in temperature or elevation, air present in ink receptacle 16 will expand. This expansion of air causes the ink to flow from ink receptacle 16 into ink flow regulating zone 14. The ink flow regulating zone being saturated has relatively little ability, if any, to accept ink from the ink receptacle. The displaced ink will therefore flow from ink flow regulating zone 14 into ink overflow zone 12. This is especially true since the zone of highest capillarity is also saturated. Since ink overflow zone 12 typically contains minimal, if any, ink, it has a great capacity to accept the displaced ink. As ink receptacle 16 returns to its normal environment (cooler relative temperature or lower altitude), air in the ink receptacle will contract, thereby sucking in either air or ink. Since ink flow regulating zone 14 and the zone of highest capillarity both have high affinity for ink, ink will migrate from ink overflow zone 12 to ink flow regulating zone 14 until the vacuum in ink receptacle 16 is equalized by the replacement of ink. If ink overflow zone 12 is void of ink, air will be suctioned into the ink overflow zone through air vent 17 and migrate to ink receptacle 16. Air will only pass through ink flow regulating zone 14 when ink overflow zone 12 is void or almost void of ink because of the high affinity of liquid in ink flow regulating zone 14 relative to affinity for liquid in ink overflow zone 12.

During printing, the printhead actively sucks ink through the ink egress port from the zone of highest capillarity. The zone of highest capillarity in turn draws ink through ink flow regulating zone 14 from either ink overflow zone 12 or ink receptacle 16. If ink overflow zone 12 contains ink, air will not pass through ink flow regulating zone 14 because of the ink flow regulating zone's high capillarity relative to the ink overflow zone. Ink migrating from ink overflow zone 12 to ink flow regulating zone 14 will displace any air or void spaces in ink flow regulating zone 14. A vacuum thereby forms in ink receptacle 16.

Since the vacuum cannot be relieved, ink is therefore supplied by ink overflow zone 12. When ink overflow zone 12 is emptied, ink flow regulating zone 14 will become partially emptied, thereby allowing air to occupy some of the void space. When this occurs, air will pass from the ink flow regulating zone 14 to ink receptacle 16, relieving the vacuum in the ink receptacle, thereby allowing ink to flow from the ink receptacle into ink flow regulating zone 14. The zone of highest capillarity remains unaffected because it remains saturated, given its high capillarity for ink.

In a preferred embodiment, the size of the ink flow regulating zone is minimized in relation to the ink overflow zone and the ink receptacle.

Thus, the flow of ink throughout the ink jet cartridge of the invention proceeds from the zone of lowest capillarity to the area of highest capillarity.

When the zone of highest capillarity is fully saturated, the flow of ink from the zone of lowest capillary ceases.

FIG. V represents yet another embodiment of the invention. The body 56 of cartridge 50 comprises ink receptacle 16, ink flow regulating zone 14, ink overflow zone 12 and egress zone 36. Partition 11a divides ink receptacle 16 and ink flow regulating zone 14. Slot 11d within partition 11a allows for the flow of ink into ink flow regulating zone 14.

Vacuum producing material 27a and 27b, preferably prefabricated blocks of absorbent material, is inserted into ink overflow zone 12 and ink flow regulating zone 14. Material 27c is inserted into egress zone 36.

Materials 27a, 27b and 27c may consist of a unitary piece of material or consist of separate pieces. Preferably, materials 27a and 27b are one unified piece of absorbent material and material 27c is a second piece. In operation, these materials have different degrees of absorbency; material 27b having a higher degree of capillarity than material 27a; material 27c having a higher degree of capillarity than material 27b. In a preferred embodiment, material 27c is a foam having 2.5 times the density of material

27b.

While material blocks 27a and 27b may be comprised of the same absorbent material and have the same density, the space limitations of ink flow regulating zone 14 are such that the capillarity of block 27b in operation will be higher than the capillarity of block 27a. This is the case even though material block 27a in operation undergoes little, if any, compression; the added density resulting from the tight aerial space of ink flow regulating zone

14 and the compression of absorbent material 27b within ink flow regulating zone 14.

Ink egress port 18, which connects to the printhead of the recording apparatus, during shipment may be capped with plug stopper 51. Added precaution may further be provided by tape 52 which encompasses plug stopper 51. An air vent 53 located within ink overflow zone 12 extends to the outside. During shipment, plug stopper 54 preferably covers air vent 53.

Removal of plug stopper 54 decreases the pressure with zone 12, thereby forcing air to be removed from the cartridge (versus ink).

In a particularly preferred embodiment of the invention, rip cord 55 is inserted between plug stopper 54 and the port of air vent 53. Release of plug stopper 54 prior to removal of plug stopper 51 will allow pressure equalization without ink leakage.

Cartridge 50 is filled with ink through ink port 57. Fill plug 58 is then inserted inside ink port 57 to prevent leakage of ink. Cover plate 59 is then welded by conventional means over cartridge body 56. Support bases 58 are provided to more evenly affix the cover plate

59 onto body wall 56.

An altemative embodiment means is provided within the ink receptacle to feed the ink into the ink flow regulating zone. FIG. IV, illustrates such a means within the cartridge illustrated by explosive view in

FIG. II. FIG. IV demonstrates the use of a transfer wicking material 42 within ink receptacle 16. The wicking material may extend into cap-24. The wicking material feeds into opening 13 of boundary wall 11a, thereby allowing the ink within ink receptacle 16 to feed into ink flow regulating zone 14 by capillary forces. This embodiment makes it possible to operate the cartridge of the invention in any orientation, including in an inverted position.

Suitable as the transfer wicking material is any material capable of absorbing ink. Preferred are polyester fibers typically used in the art as well as bonded aligned fibers.

It is further possible to employ a transfer wicking material as an extension of the zone of highest capillarity to the point of connection of the cartridge with the printer. In this regard, the zone of highest capillarity acts as a conduit of the ink to the wicking material.

When the cartridge is filled, it is beneficial to minimize the air present in ink receptacle 16. This maximizes liquid capacity and reduces liquid displacement from ink receptacle 16 to ink flow regulating zone 14 as well as decreasing ink overflow to ink overflow zone 12. Ink volumetric efficiency is further increased while permitting the cartridge to be subjected to a wide range of environmental conditions without ink leakage.

Since the cartridge of the invention relies on zones of capillarity and is relatively unaffected by gravity or vibration, it is possible to ship a completely-filled cartridge while connected to the printhead even with vent 22b open to ambient conditions.

Inks useful for the ink jet cartridges of the invention include those inks having a viscosity of between about 1 to about 12 cps, preferably about 8 to about 12 cps, a surface tension between about 20 to about 70 dynes, preferably between about 30 to about 65 dynes, and a pH of between about 3 to about 11. Such inks are typically comprised of from about 40 to about 98 weight percent water, up to about 10 weight percent dye or pigment, from about 0 to about 40 weight percent water soluble organic solvents or humectants and from about 0 to about 10 weight percent surfactants or other conventional additives such as biocides, buffers and salts. The invention is not restricted to any particular aqueous or solvent based ink nor to a particular dye or pigment.

Various modifications may be made in the nature, composition, operation and arrangement of the various elements, steps and procedures described herein without departing from the spirit and scope of the invention as defined in the following claims.

Claims

What is claimed is: 1. An ink jet cartridge comprising: (a) an ink retention cavity; (b) a first zone adjacent to at least a portion of the ink retention cavity and separated by a partition, said partition having openings for flowing liquid ink from the ink retention cavity into the first zone; (c) a second zone extending from said first zone, the degree of capillarity of said second zone being less than the degree of capillarity of said first zone, said second zone being partitioned from the ink retention cavity and having an air vent for admitting ambient air thereto; and (d) an ink egress port posterior to said first zone. 2. The ink jet cartridge of claim 1 , wherein the first and second zones contain a vacuum producing material. 3. The ink jet cartridge of claim 1 , wherein the vacuum producing material is selected from a foam-like or sponge-like material, porous plastic, nylon, sand, felt or glass beads. 4. The ink jet cartridge of claim 3, wherein the vacuum producing material is selected from the group of polyether foams, polyester foams and polyurethane foams. 5. The ink jet cartridge of claim 1 , further comprising a third zone posterior to said first zone, the capillarity of which is greater than the capillarity of the first zone. 6. The ink jet cartridge of claim 1 , wherein the ink retention cavity contains a wicking substance which empties into the openings of the partition. 7. The ink jet cartridge of claim 1 , further comprising compressible means for decreasing the volume of ink within the ink retention cavity. 8. The ink jet cartridge of claim 1 , wherein the liquid ink comprises water, coloring material and water-soluble organic solvent and has a surface tension of about 20 dynes/cm to about 70 dynes/cm. 9. The ink jet cartridge of claim 1 , wherein said cartridge is comprised of semitransparent plastic. 10. An ink jet cartridge comprising: (a) a cavity for retaining liquid ink; (b) a first zone adjacent to a portion of the cavity, and separated therefrom by a partition, said partition having an opening for passing the liquid ink from the cavity into the first zone; (c) a second zone extending from said first zone, the degree of capillarity of said second zone being less than the degree of capillarity of the first zone, the second zone being partitioned from the cavity and having an air vent for admitting ambient air thereto; and (d) a third zone adjacent to the first zone having a degree of capillarity greater than the degree of capillarity of the first zone, the posteriormost surface of said third zone being an egress port for the liquid ink. 11. The ink jet cartridge of claim 10, wherein the third zone is comprised of porous plastic or bonded aligned fibers. 12. The ink jet cartridge of claim 10, wherein the second and third zones contain a vacuum-producing material. 13. The ink jet cartridge of claim 10, wherein the first, second and third zones contain a vacuum producing material. 14. The ink jet cartridge of claim 12, wherein the vacuum producing material is selected from a foam-like or sponge-like material, nylon, porous plastic, sand, felt or glass beads. 15. The ink jet cartridge of claim 14, wherein the vacuum producing material is a polyether foam, polyester foam or polyurethane foam. 16. The ink jet cartridge of claim 10, wherein the cavity contains a wicking substance which empties into the openings of the partition. 17. The ink jet cartridge of claim 10, further comprising compressible means for decreasing the volume of ink within the cavity. 18. The ink jet cartridge of claim 10, wherein the liquid ink comprises water, coloring material and water-soluble organic solvent and has a surface tension of about 20 dynes/cm to about 70 dynes/cm. 19. An ink jet cartridge comprising an ink receptable, a plurality of interconnected zones comprising an ink flow regulating zone, an ink overflow zone having an air vent for admitting ambient air thereto and an ink egress zone, the ink egress zone terminating at an ink egress port, the ink flow regulating zone having a higher degree of capillarity than the ink overflow zone and the ink egress zone having a higher degree of capillarity than the ink flow regulating zone, the ink overflow zone, ink flow regulating zone and ink egress zone containing a vacuum producing material; wherein at least a portion of one end of the ink flow regulating zone is adjacent to the ink receptacle and separated therefrom by a partition and at least a portion of the other end of the ink flow regulating zone is adjacent to the ink egress zone, the ink overflow zone being contagious to the ink flow regulating zone though partitioned from the ink receptacle; said ink jet cartridge further containing at least one opening within the partition separating the ink receptacle and the ink flow regulating zone. 20. The ink jet cartridge of claim 19, wherein the vacuum producing material is selected from a foam-like or sponge-like material, porous plastic, nylon, sand, felt or glass beads. 21. The ink jet cartridge of claim 20, wherein the vacuum producing material is selected from the group of polyether foams, polyester foams and polyurethane foams. 22. The ink jet cartridge of claim 20, wherein the ink receptacle contains a wicking substance which empties into the opening of the partition. 23. The ink jet cartridge of claim 20, further comprising a resilient means for decreasing the volume of ink within the ink receptacle. 24. An ink jet cartridge comprising interconnected zones and an ink retention cavity, each of the interconnected zones containing an absorbent material providing varying degrees of capillarity, the zone of highest capillarity feeding through an egress port into the printhead of the printer and being adjacent to the ink retention cavity and separated therefrom by a partition, said partition having means for flowing liquid ink from the ink retention cavity into the zone of highest capillarity, the zone of lowest capillarity being a lateral extension of the zone of highest capillarity. 25. An ink jet cartridge comprising three interconnected zones and an ink retention cavity, each of the interconnected zones containing an absorbent material providing varying degrees of capillarity, the zone of highest capillarity feeding into an egress port and being anteriorly bound by the zone of medium capillarity, the zone of medium capillarity being separated from the ink retention cavity by a partition, said partition having means for flowing liquid ink from the ink retention cavity into the zone of medium capillarity, the zone of lowest capillarity being a lateral extension of the zone of medium capillarity.