Slingshot Printing LLC v. HP Inc.

Western District of Texas, txwd-6:2019-cv-00362

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2 USOO6394593B1 (12) United States Patent (10) Patent No.: US 6,394,593 B1 Komplin et al. (45) Date of Patent: May 28, 2002 (54) VENT SYSTEM FOR INKJET PEN HAVING 5,844,577 A 12/1998 Pawlowski, Jr. ............... 347/6 INTERNAL PRESSURE REGULATOR 5,936,650 A 8/1999 Ouchida et al. .............. 347/85 5,980,032 A 11/1999 Pawlowski, Jr. et al. ..... 347/86 (75) Inventors: Steven Robert Komplin; James 2Y------ a t A '' split al. .............. i. CW C al. . ... . .. ... ... .. . .. .. Hald Powers, both of Lexington, KY 6,033,064 A 3/2000 Pawlowski, Jr. et al. ..... 347/87 () 6,120,138 A 9/2000 Xiao et al. .................... 347/85 (73) Assignee: Lexmark International,9 Incs 6,137,513 A 10/2000 Pawlowski, Jr. et al. ..... 347/86 Lexington, KY (US) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term of this JP 09 156124 6/1997 patent is extended or adjusted under 35 JP 10 s 6/1998 U.S.C. 154(b) by 0 days. JP 11 10530 4/1999 Primary Examiner Anh T. N. Vo (21) Appl. No.: 09/870,204 (74) Attorney, Agent, or Firm-David E. LaRose; Luedeka, (22) Filed: May 30, 2001 Neely & Graham (51) Int. Cl." ................................................. B41J 2/175 (57) ABSTRACT (52) U.S. Cl. ......................................................... 347/86 The invention relates to a vent System for an inkjet pen of (58) Field of Search .............................. 347/84, 85, 86, the type having an internal pressure regulator. The vent 347/87 System provides air flow communication between the eXte rior of the inkjet pen and an interior chamber associated (56) References Cited with the pressure regulator while Substantially inhibiting the U.S. PATENT DOCUMENTS flow of water vapor out of chamber to the exterior of the pen. The vent System includes an elongate flow path defined 5,526,030 A 6/1996 Baldwin et al. .............. 347/87 adjacent the exterior of the pen, the flow path having a first 5. A 7/1996 Flyn et al - - - - - 347/85 end in flow communication with the chamber and a Second 600,358 A 5,736,992 A 2/1997 Baldwin et al. .............. 347/87 4/1998 Pawlowski, Jr. ............... 347/7 end in flow communication with the exterior of the pen. 5,777,647 A 7/1998 Pawlowski, Jr. et al. ..... 347/86 5.841,454 A 11/1998 Hall et al. .................... 347/87 18 Claims, 6 Drawing Sheets 92 90 2 2 U.S. Patent May 28, 2002 Sheet 1 of 6 US 6,394,593 B1 / -- 2 U.S. Patent May 28, 2002 Sheet 2 of 6 US 6,394,593 B1 2 U.S. Patent May 28, 2002 Sheet 3 of 6 US 6,394,593 B1 2 2 2 U.S. Patent May 28, 2002 Sheet 6 of 6 US 6,394,593 B1 2 US 6,394,593 B1 1 2 VENT SYSTEM FOR INKJET PEN HAVING jet pen of the type having an internal pressure regulator. The INTERNAL PRESSURE REGULATOR vent System provides air flow communication between the FIELD OF THE INVENTION exterior of the inkjet pen and an interior chamber associated with the pressure regulator while Substantially inhibiting the The invention relates to an improved inkjet printhead and flow of water vapor from the chamber to the exterior of the to a vent System for maintaining desirable environmental pen. conditions within the printhead. In a preferred embodiment, the invention provides an ink jet pen having an exterior portion and an interior portion, BACKGROUND and a pressure regulator within the interior portion including Inkjet printers typically include a print head having either a chamber associated therewith. The vent System is provided heaters or piezoelectric devices for ejecting ink during by an elongate air flow path defined adjacent the exterior of printing. In either case, liquid ink is directed from a reservoir the pen, the flow path having a first end in flow communi to a plurality of chambers, each associated with a heater or cation with the chamber of the internal pressure regulator piezoelectric device and a nozzle. The heaters/piezoelectric and a Second end in flow communication with the exterior of devices are electronically controlled to eject ink in a desired 15 the pen. It is particularly preferred that the vent System be Sequence that corresponds to the image to be printed. configured to substantially inhibit water vapor flow to the To provide desirable conditions for controlling the flow of exterior of the pen from the chamber of the pressure regu ink from the reservoir to the chambers, the reservoir may lator. initially be placed under a condition of a slight vacuum with In another aspect the invention provides an ink cartridge respect to ambient pressure. The vacuum condition is com for an inkjet printer. The cartridge includes a body portion monly referred to as a "backpressure'. In order to maintain including a first panel portion having an interior Surface a desired backpressure in the reservoir throughout the oper opposite an exterior Surface, a Second panel portion attach ating life of the printhead, a pressure regulating device may able to the body portion to define a cavity for containing ink be included. The preSSure regulating device is intended to between the first panel portion and the Second panel portion, help maintain a desired negative pressure in the reservoir 25 and a chamber defined within the cavity adjacent the interior and adjust against pressure changes in the reservoir resulting Surface of the body portion. A lung type preSSure regulator from, for example, increases or decreases in operating is disposed within the cavity adjacent the chamber. An air temperatures and pressures (e.g., hot, cold or altitude diffusion path provides flow communication between the changes or pressure changes associated with air travel) and exterior surface of the body portion and the chamber. The air from pressure changes associated with a decrease of the diffusion path includes an elongate flow path defined adja Volume of ink in the reservoir through use of the printhead. cent the exterior surface of the body portion, the flow path One problem associated with pressure regulators is that having a first end in flow communication with the chamber the pressure regulators are often made from materials that and a Second end in flow communication with the exterior are permeable to water vapor. Water evaporating from the surface of the body portion, whereby flow of water vapor out ink tends to flow by diffusion to areas of lower relative 35 of the chamber is significantly inhibited. humidity, in this case, the pressure regulator chamber. The As described in more detail below, the vent system relative humidity of the pressure regulator chamber is advantageously helps to maintain a desirable climate within affected by air flow into the chamber from the atmosphere chamber of the pressure regulator So that water evaporation exterior to the ink reservoir as the volume of ink in the from the ink is inhibited. In particular, the vent System is reservoir decreases. The flow of air affects the relative 40 configured to maintain a relatively humid environment humidity of the chamber providing a relative humidity within the chamber associated with the pressure regulator differential that induces water evaporation from the ink and while permitting air flow into and out of the chamber. By net water vapor flow into the chamber. maintaining the humidity of the chamber above a desired Some printheads further include so-called "bubble gen value, water vapor permeation through the lung material erators." Bubble generators generally include a valved ori 45 from the ink is minimized. Hence the water content of the fice that permits controlled flow communication of air ink in the pen over time remains relatively constant. LOSS of between the interior and the exterior of the ink reservoir. water from the ink is detrimental to the operation of the pen. Such bubble generators are generally designed to permit air In addition, when incorporated in inkjet pens of the type to "bubble' into the reservoir to increase the pressure within having a bubble generator in flow communication with the the reservoir (i.e., reduce the vacuum). A problem attendant 50 chamber of the pressure regulator, the vent System functions to bubble generators is leakage of ink to the exterior of the to reduce the incidence of ink leakage to the exterior of the reservoir. Another problem is drying of ink in the reservoir pen. adjacent the bubble generator which leads to dysfunction, BRIEF DESCRIPTION OF THE DRAWINGS causing undesirable reservoir environmental conditions and Further advantages of the invention will become apparent reduction in printhead operation and longevity. 55 The present invention relates to a vent System for use with by reference to the detailed description when considered in inkjet pens of the type having internal pressure regulators. conjunction with the figures, which are not to Scale, wherein The vent System advantageously functions to maintain desir like reference numbers indicate like elements through the able environmental conditions within the inkjet pen for Several views, and wherein: improved pen operation and longevity. In addition, for pens 60 FIG. 1 is an inside perspective view of a first portion of of the type having an internal pressure regulator in flow an ink cartridge body of a printhead into which the vent communication with the bubble generator, the vent System System of the present invention may be incorporated; functions to inhibit ink leakage from the pen. FIGS. 2 and 2a are outside perspective views of the ink cartridge body portion of FIG. 1; SUMMARY OF THE INVENTION 65 FIG. 3 is a top perspective view of a printhead body for With regard to the above and other objects and use with a printhead made using the ink cartridge body advantages, the invention provides a vent System for an ink portion of FIG. 1; 2 US 6,394,593 B1 3 4 FIG. 4 is an inside perspective view of a Second portion below with reference to FIGS. 5 and 6 serves to maintain a of an ink cartridge body that is combinable with the first predetermined pressure in cavity 12 as the Volume of ink in portion of FIG. 1; the cavity decreases. The pressure regulator 98 also helps to FIG. 5 is a perspective View of a lung-type pressure compensate for pressure changes in ink cavity 12 due to regulator incorporated into the first body portion of FIG. 1; temperature, ambient pressure in the printer or cartridge environment and the like. FIG. 6 is a cross-sectional view of a printhead having a In order to maintain the preSSure in the ink cavity 12 lung-type pressure regulator and incorporating a vent System above a predetermined minimum pressure, the bubble gen in accordance with the invention. erator 40 is selected to induce gas flow into cavity 12 while DETAILED DESCRIPTION OF THE preventing flow of ink out of cavity 12. The gas flow bubbles PREFERRED EMBODIMENTS entering the cavity 12 flow through the ink and accumulate in an upper portion of cavity 12 above the ink level. In this The invention relates to a vent system 4 for use with an way, the pressure in cavity 12 is maintained above a prede inkjet pen 6 of the type having an internal preSSure regulator termined minimum pressure. In most applications, the pre 8. The vent system 4 advantageously functions to inhibit ink 15 determined minimum pressure or back pressure ranges from leakage from the pen 6 and to maintain desirable environ about -12 to about -24 centimeters (cm) of water. mental conditions within the inkjet pen for improved pen The ball 44 inserted in aperture 42 has a diameter ranging operation and longevity. from about 1 to about 5 millimeters, preferably about 3 The pen 6 with which the vent system 4 is used preferably millimeters and is preferably made of a corrosion resistant includes a lung-type internal pressure regulator 8. The material compatible with the ink in the ink cartridge body preferred configuration for the basic construction of a pen 6 10. Such corrosion resistant materials include but are not having an internal pressure regulator 8 for use with the vent limited to glass, ceramic, StainleSS Steel, fluorocarbon poly system 4 of the present invention is described in U.S. Pat. merS and the like. The most preferred material is stainless No. 6,168,267, issued on Jan. 2, 2001 Komplin and entitled Steel. "PRESSURE CONTROLLED INK CARTRIDGE 25 The pressure regulator 8 is preferably a lung-type regul (ASSigned to Lexmark International, Inc.), the disclosure of lator 98 having a lung chamber 66 defined by lung frame which is incorporated herein by reference in its entirety. walls 70, 72, 74 and 76 and a portion of first side panel 22 Accordingly, and with initial reference to FIGS. 1 and 2, lying within the area defined by lung frame walls 70, 72, 74 the pen 6 preferably includes a Substantially rectangular ink and 76. At least one of the lung frame walls preferably has cartridge body 10 containing an interior cavity 12 for a Surface, Such as the Surface of lung frame wall 70 adjacent containing ink. The body 10 has first, second, third and the bubble generator 40 which promotes gas bubble forma fourth side walls 14, 16, 18 and 20 defining the perimeter of tion in the interior cavity 12 (FIG. 1). Lung frame wall 70 cavity 12. The side walls 14-20 are each attached to a first is preferably angled with respect to an axis parallel with side panel portion 22. Side wall 18 may contain a handle or cartridge Side wall 14 thereby providing increasingly greater preferably contains ridges 24 and 26 which are disposed 35 spacing between lung frame wall 70 and cartridge Side wall toward opposite ends 28 and 30 of side wall 18 for use in 14 proceeding from cartridge Side wall 16 to cartridge Side inserting and removing ink cartridge body 10 from a print wall 20. head body 31 (FIG.3). Side wall 18 is preferably arc-shaped A number of advantages are provided by use of a lung so that side wall 20 has a length greater than side wall 16. Structure possessing angled lung frame wall 70. One advan Side wall 20 also preferably contains a latch 32 for attaching 40 tage is that because frame wall 70 is not closely adjacent the ink cartridge body 10 to a printhead body 31 of an ink aperture 42, there is less inhibition of bubble formation as jet printer. gas flows into cavity 12 through aperture 42 of bubble Side wall 16 of the cartridge body 10 preferably contains generator 40. Less inhibition of bubble formation results in a plurality of staggered tabs such as tabs 34, 36 and 38 which a greater range of preSSure control in cavity 12. may be removed to provide identification of the ink cartridge 45 Another advantage is that there is more room between with respect to its proper location in a printhead body 31. lung frame walls 70, 72, 74 and 76 and cartridge side walls The tabs 34, 36 or 38 may be removed as by cutting or 14, 16, 18 and 20 for tooling used to form cartridge side breaking the tabs from Side wall 16 to define an ink cartridge walls 14, 16, 18 and 20 and lung frame walls 70, 72, 74 and containing tab 34, tab 36 or tab 38 which is made to 76. The increased tooling room provides an increased cool correspond to keying channels 33, 35 or 37 of cartridge slots 50 ing rate of the cavity side of side walls 14, 16, 18 and 20 39, 41 or 43 of the printhead body 31 (FIG. 3). A wider which in turn reduces the warpage of cartridge Side walls 14, cartridge body similar to cartridge body 10, preferably 16, 18 and 20 caused by unequal cooling through the containing no removable tabs, is insertable in cartridge Slot thickness of the wall material. Reducing the warpage of Side 45 of the printhead body 31. walls 14, 16, 18 and 20 increases the ability to form gas and Referring again to FIG. 1, a bubble generator 40 which 55 liquid tight seals between second side panel 78 (FIG. 4) and includes an aperture 42 and a ball 44 is preferably disposed the welding ledge 80 around the periphery of the cartridge in the first side wall 14 of the rectangular cartridge body 10. body 10 defined by the edges of cartridge side walls 14, 16, The aperture 42 of the bubble generator 40 is in fluid flow 18 and 20. communication with the interior cavity 12 of the body 10. The sloping configuration of lung frame wall 70 also Aperture 42 provides an orifice for the bubble generator 40. 60 functions to direct ink or other liquids which may have After the cavity 12 is filled with ink, a reduced pressure flowed into lung chamber 66 toward aperture 64 thereby or back pressure is applied to the cavity 12, preferably improving the drainage rate of liquids or ink from chamber through an ink feed port 94, described below, to provide a 66. It is thus preferred to locate aperture 64 in an apexial area predetermined preSSure differential between cavity 12 and of chamber 66 defined by the intersection of frame walls 70 an inkjet printhead. AS ink is ejected by a printhead, the 65 and 72 as shown in FIG. 1. Volume of ink in cavity 12 decreases. A pressure regulator Another advantage of the sloped or angled orientation of 98, preferably a lung, which is described in more detail lung frame wall 70 is the provision of areas 84 and 82 2 US 6,394,593 B1 S 6 between cartridge side walls 14 and 16 and lung frame walls rial sheet, such as adhesive strip 93 is adhesively secured to 70 and 72 respectively. Area 84 preferably has dimensions the surface 83 to cover substantially all of the channel 81, Sufficient to provide for a ball check valve Support Structure except for a portion adjacent the end 87. As will be 86 for a ball check valve device. Support structure 86 appreciated, the material 93 defines a boundary for the preferably includes rounded edges 88 and is adapted to channel 81 to provide an enclosed flow path or conduit guide a ball valve 90 and an urging device for ball valve 90 extending from the aperture 91 to the end 87 for travel of air Such as Spring 92 in a linear direction through aperture 94 and inhibition of water vapor diffusion therein. The term toward and away from boSS 96 containing an elastomeric "Substantially vapor impermeable" means that the transmis Septum 97 upon removal and insertion of an ink Supply sion of water vapor through the cover 93 is substantially less needle of a needle valve assembly 95 (FIG. 3) through boss than the diffusion of water vapor out of end 87 of the conduit 96, septum 97 and associated aperture 94. Septum 97 used 81 to the atmosphere. for Sealing boSS 96 includes a Septum made from a variety For ink jet pens having a bubble generator in flow of natural and Synthetic rubber materials. During use, an ink communication with the internal pressure regulator, Such as supply needle contacts ball valve 90 causing ball valve 90 to the bubble generator 40 being linked to the chamber 66 by recede from septum 97 thereby enabling ink to flow from 15 the vent 64, the vent system 4 advantageously inhibits cavity 12 through the needle to a corresponding printhead on leakage of ink to the exterior of the pen. For example, it will the printhead body 31 (FIG. 3). Upon removal of a needle be appreciated that ink leaking from the cavity 12 through from boss 96, ball valve 90 is urged by spring 92 toward the bubble generator 40 flows into the lung chamber 66 via septum 97 so that ball valve 90 again seals against the the vent 64. In order for this leaked ink to exit to the exterior septum 97 to prevent flow of ink therethrough when the of the pen 6, it must then exit the chamber 66 via the aperture cartridge body 10 is not attached to a printhead body 31. 91 and travel the length of the conduit provided by the channel 81/cover 93. The ball valve 90 and spring 92 are preferably constructed With reference to FIGS. 5 and 6, the lung 98 preferably of ink resistant materials. Such materials include but are not limited to glass, ceramic, fluorocarbon polymers and metals. includes lung chamber 66 defined by lung frame walls 70, Aparticularly preferred material for ball valve 90 and spring 25 72, 74 and 76 (FIG. 1) and a portion of first side panel 22 92 is stainless steel. lying with the area defined by frame walls 70, 72, 74 and 76. Returning to FIG. 1, area 82 in cavity 12 provides a A resilient flexible polymeric material 100 is attached to the peripheral edge 102 defined by frame walls 70, 72, 74 and Suitable location for a level Sensor for detecting the amount 76. The flexible polymeric material 100 may be selected of ink remaining in ink cavity 12. If lung frame wall 72 were from films that are compatible with the material used for Substantially parallel to cartridge Side wall 16, the distance forming the ink cartridge body 10 and inks used in the ink between frame wall 72 and cartridge side wall 16 would not cartridge and films adaptable to welding or adhesive attach be Sufficient for many of the ink level Sensing devices ment thereof to the lung frame walls 70, 72, 74 and 76. A commonly used with ink cartridges Such as magnetic level particularly preferred flexible polymeric material 100 a Sensors, photo-reflective level Sensors, ultraSonic level 35 copolymer polypropylene material available from Triangle Sensors, float-type level Sensors and the like. Plastics of Raleigh, N.C. under the trade name CPP40. The While the above advantages of an angled lung frame wall flexible polymeric material 100 is permeable to water vapor 70 have been described generally with respect to substan and therefore enables water evaporated from the ink in tially rectangular lung chamber 66, Similar results may be cavity 12 to flow into chamber 66. obtained with lung frame walls which is substantially 40 The conduit provided by the channel 81/sheet 93 enables circular, oval, triangular or other polygonal shape providing air flow communication between the chamber 66 and the there is increasingly greater Spacing between frame wall 70 external atmosphere while substantially inhibiting the dif and cartridge Side wall 14 when moving from cartridge Side fusion of water vapor in the channel 81 between the chamber wall 16 to cartridge side wall 20. 66 and the exterior of the pen. This feature has been Returning to FIG. 2, there is shown the body 10 having a 45 observed to beneficially provide an environment within the serpentine groove or channel 81 on an exterior surface 83 of chamber 66 that is of relatively high humidity (e.g., from side panel 22 thereof opposite an interior surface 85 of the about 60% relative humidity (RH) to about 100% RH). ink cartridge 10. The channel 81 is continuous between Maintenance of Such desirable humidity reduces the pres opposite ends 87 and 89, with an aperture 91 located Sure difference driving vapor permeation through the poly adjacent end 89 extending between the surfaces 83 and 85. 50 meric material 100 and reduces the partial pressures of the The channel 81 is preferably formed during molding of the dry gas constituents of air (predominantly nitrogen and body 10. oxygen), So as to reduce the partial pressure differences, The channel 81 preferably has a length of from about 10 which affect air permeation through the polymeric material mm to about 600 mm and a substantially uniform cross 100. This is beneficial to extend the shelf and service life of Sectional area defining a conduit having a cross-sectional 55 the pen 6 and also of pens not having the bubble generator area of from about 0.2 mm° to about 2.0 mm. The aperture linked to the internal preSSure regulator. 91 is preferably circular, with a radius corresponding to that After heat attaching the polymeric material 100 to frame of the channel. The channel 81 may be Straight, Serpentine walls 70, 72, 74 and 76, the material 100 is heated while or other labyrinth shape, provided the ratio of the channel applying a reduced pressure to lung chamber 66 by means of overall length (L) to its cross-sectional area (CA) for flow 60 vent hole 64 or aperture 91 thereby causing material 100 to ranges from about 20 mm (L) to about 6000 mm (L/CA). closely conform to lung chamber 66. Heating the material The channel 81 is preferably substantially centrally located 100 while applying reduced pressure to lung chamber 66 has on the surface 83, with the aperture 91 being located within been found to reduce Wrinkles and improve the preSSure the boundaries of the lung frame walls 70-76 so that the response of pressure regulator 98. Prior to filling cavity 12 aperture 91 is located adjacent the lung frame wall 72. 65 with ink, a piston member 106 and urging member 108 are With reference now to FIG. 2a, a substantially vapor and inserted in cavity 12 within the perimeter of frame walls 70, liquid impermeable cover, preferably a flexible plastic mate 72, 74 and 76 for urging polymeric material 100 toward first 2 US 6,394,593 B1 7 8 Side panel portion 22. A Second Side panel 78 is then attached Having described various aspects and embodiments of the to the first, second, third and fourth side walls 14, 16, 18 and invention and Several advantages thereof, it will be recog 20 of the cartridge body 10. A ball 44 is inserted in the nized by those of ordinary skills that the invention is aperture 42 of the bubble generator 40 (FIG. 1) and a film Susceptible to various modifications, Substitutions and revi is applied over channel 110 and aperture 64 to seal the Sions within the Spirit and Scope of the appended claims. aperture 64 and channel 110 connecting apertures 42 and 64. What is claimed is: The cavity 12 is then filled with ink and a reduced pressure 1. An ink cartridge for an inkjet printer, the cartridge is applied to cavity 12. comprising a body portion including a first panel portion Despite the use of an angled pressure regulator 98 in having an interior Surface opposite an exterior Surface cavity 12, side walls 14, 16, 18 and 20 (FIG. 1) may still be exposed to an atmosphere having an atmospheric pressure, Slightly warped or bowed as a result of the injection molding a Second panel portion attachable to the body portion to proceSS used to form cartridge 10. In order to counteract the define a cavity for containing ink between the first panel tendency for side walls 14, 16, 18 and 20 to bow or warp, portion and the Second panel portion, and a chamber defined Second Side panel 78 is adapted to contain urging members within the cavity adjacent the interior Surface of the first 118 (FIG. 4) which are preferably disposed in predetermined panel portion of the body portion, a lung type preSSure 15 regulator disposed within the cavity adjacent the chamber, locations on second side panel 78. Urging members 118 are preferably upstanding, Substantially rectangular tabs con and an air diffusion path for providing flow communication taining a chamfered edge Such as edge 122 which assists in between the chamber and the atmosphere, the air diffusion urging side walls 14, 16, 18 and 20 outwardly so to maintain path comprising an elongate flow path defined on the first the planarity of side walls 14, 16, 18 and 20 to reduce the panel portion of the body portion, the flow path having a first inward bowing of the side walls for sealably welding weld end in flow communication with the chamber and a Second projection 124 to the welding ledge 80 of cartridge body 10 end located on the exterior Surface of the first panel portion (FIG. 1). Five urging members 118 are shown on side panel of the body and in flow communication with the atmosphere, 78, however, side panel 78 may contain more or fewer whereby the flow path enables air flow communication urging members 118 as the need arises and depending on the between the chamber and the atmosphere while substantially length of side walls 14, 16, 18 and 20 of body 10. 25 inhibiting flow of water vapor out of the chamber. Another feature of second side panel 78 is raised wall 120 2. The ink cartridge of claim 1 wherein the flow path which is disposed inward of weld projection 124 and pro comprises a channel on the exterior Surface of the first panel vides protection for the Weld projection 124 against damage portion of the body portion, the channel having a first end during handling of the second side panel 78. Protection of and a Second end, the first end including an aperture extend Weld projection 124 is desirable because the Weld projection ing between the interior and exterior Surfaces of the first 124 is relatively flimsy and may be easily damaged if panel portion, and a Substantially liquid and gas imperme bumped or otherwise struck with a foreign object. The weld able cover positioned over all portions of the channel except projection 124 provides a site for ultrasonically welding a terminal portion adjacent the Second end of the channel. second panel 78 to the welding ledge 80 of body 10. In the 3. The ink cartridge of claim 1 wherein the flow path is alternative, an adhesive may be applied to ledge 80 or to the 35 Substantially Serpentine. second side panel 78 in the absence of weld projection 124 4. The ink cartridge of claim 1 wherein the flow path is to adhesively attach the side panel 78 to the cartridge body Substantially Straight. 10. Welding or adhesives are required to provide a liquid and 5. The ink cartridge of claim 1 wherein the flow path has gas tight seal between body 10 and panel 78 so as to avoid a cross-sectional area ranging from about 0.1 to about 2.0 ink leakage, evaporation of liquid ink components and/or 40. undesired pressure changes within cavity 12. 6. The ink cartridge of claim 1 wherein the ratio of flow Another aspect of side panel 78 is guiding member 126 path length to flow path cross-sectional area ranges from which includes a guide bar 128 and a stop member 130. about 20 mm to about 6000 mm. Guide bar 128 is positioned to be spaced between the two 7. An ink cartridge for an inkjet printer, the cartridge portions of Support structure 86 (FIG. 1) so as to retain ball 45 comprising a body portion including a first panel portion valve 90 and spring 92 between guide bar 128 and rounded having an interior Surface opposite an exterior Surface edges 88 of support structure 86. Stop member 130 provides exposed to an atmosphere having an atmospheric pressure, a retainer for Spring 92 So that Spring 92 can exert urging a Second panel portion attachable to the body portion to resistance on ball valve 90 thereby sealing orifice 94 when define a cavity for containing ink between the first and the cartridge body 10 is not attached to a printhead body 31. 50 Second panel portions, a chamber defined within the cavity With respect to the cartridge body 10 and second panel 78, adjacent the interior Surface of the first panel portion of the all of the features described above, with the exception of the body portion, a water vapor permeable lung type preSSure ball 44, ball valve 90, spring 92, flexible polymeric material regulator disposed within the cavity adjacent the chamber, 100, piston member 106 and urging member 108 are molded and a vent System for air flow communication between the into the cartridge body 10 and side panel 78. Accordingly, 55 chamber and the atmosphere, the vent System comprising an body 10 and side panel 78 are preferably molded from elongate flow path defined on the first panel portion of the materials Selected from the group of thermoplastic materials body portion, the flow path comprising a channel on the including but not limited to polyphenylene oxide/ exterior Surface of the first panel portion of the body portion, polystyrene alloys, polypropylene, acrylonitrile/butadiene/ the channel having a first end and a Second end, the first end Styrene terpolymers, polystyrene/butadiene alloys or 60 including an aperture extending between the interior and copolymers, polyetherimide, poly Sulfone, polyesters and the exterior Surface of the first panel portion, and a Substantially like. A particularly preferred material for body 10 and panel liquid and vapor impermeable cover positioned over all 78 a polypropylene material having a melt flow rate of about portions of the channel except a terminal portion adjacent 12 grams per 10 minutes according to ASTM D-1238 and a the second end of the channel, whereby the flowpath enables density of about 0.9 grams/cm according to ASTM D-1505 65 air flow communication between the chamber and the atmo available from Huntsman Polypropylene Corporation of sphere while substantially inhibiting flow of water vapor out Woodbury, N.J. under the trade name P4G4B-036. of the chamber. 2 US 6,394,593 B1 9 10 8. The ink cartridge of claim 7 wherein the flow path is 13. The vent system of claim 12, wherein the flow path Substantially Straight. comprises a channel on the exterior of the pen, the channel 9. The ink cartridge of claim 7 wherein the flow path is having a first end and a Second end, the first end including Substantially Serpentine. an aperture extending between the exterior of the pen and the 10. The ink cartridge of claim 7 wherein the flow path has chamber, and a Substantially liquid and vapor impermeable a cross-sectional area ranging from about 0.1 to about 2.0 cover positioned over all portions the channel except a mm. terminal portion adjacent the Second end of the channel. 11. The ink cartridge of claim 7 wherein the ratio of flow 14. The vent system of claim 12, wherein the flow path is path length to flow path cross-sectional area ranges from Substantially Serpentine. about 20 mm to about 6000 mm. 15. The vent system of claim 12 wherein the flow path is 12. In inkjet pen having an exterior portion and an interior Substantially Straight. portion, and a pressure regulator within the interior portion 16. The vent system of claim 12 wherein the flow path has including a chamber associated there with, the improvement a cross-sectional area ranging from about 0.1 to about 2.0 comprising a vent System provided by an elongate air flow mm. path defined on an exterior Surface of the pen, the flow path 15 17. The vent system claim 12 wherein the ratio of flow having a first end in flow communication with the chamber path length to flow path cross-sectional area ranges from of the internal pressure regulator and a Second end in flow about 20 mm to about 6000 mm. communication with the exterior Surface of the pen, the vent 18. The vent system of claim 13, wherein the cover System being configured to Substantially inhibit water vapor comprises a flexible sheet material. flow to the exterior of the pen from the chamber of the preSSure regulator. k k k k k