Patent Publication Number: US-6666552-B2

Title: Diaphragm/check valve used in inkjet cassette to air removal for extended life storage

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Provisional Application No. 60/239,084 filed on Oct. 6, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to the art of cartridges for dispensing ink, and more particularly, to cartridges for dispensing ink that use a reduced-pressure area in the cartridge to more efficiently use the capacity of the cartridge, to increase the shelf life and quality of the ink dispensed, and to minimize leakage from the cartridge by minimizing the volume and pressure of extraneous fluids (e.g., air) retained in the cartridge and in the ink therein. 
     Cartridges for dispensing ink have been provided heretofore, and generally are comprised of a housing having a cavity therein for storing a quantity of ink, and a dispensing port extending through the housing from the cavity through which ink may flow. Such a cartridge is operatively associated with an output recordation device, such as a printer. Typically, the printer has a printhead, and the dispensing port is in fluid communication with the printhead so that ink can be transferred from the cavity in the cartridge to the output medium, such as paper. 
     A housing generally has a top wall, such as a cover, that extends across the top of the housing to fully enclose the cavity. The cover is secured to the housing forming a fluid-tight seal along a seam between the housing and the cover. One or more ports, in addition to the dispensing port, may extend through the housing to permit the ingress and egress of ink or air. Once the cover has been secured to the housing and the cartridge has become a generally closed container, the cartridge is filled with ink. At various stages throughout this filling process, the dispensing port and other ports will be sealed to prevent leakage and evaporation of the ink. 
     In ink cartridges of the foregoing character, air may be retained in the cartridge during the filling process. The trapped air can mix into the ink during the filling process or after the filling process. This can reduce the storage life of the ink cartridge, result in interruption of ink flow from the cartridge and lead to a reduction in the quality of output from a printer using such a cartridge. Air trapped in the cartridge may expand in response to temperature or pressure changes and thereby undesirably force some of the stored ink from the cartridge. To minimize such print voids or other problems, ink cartridges are often filled in a reduced-pressure environment. A variety of difficulties are encountered when employing such a filling procedure. The filling operation often requires expensive equipment to perform the filling operation under these conditions. Sealing the port in a conventional manner, such as by plugging or covering the ports, does not overcome the problem of air entrapped in the cartridge either prior to or during the filling process. Furthermore, once the cartridge has been sealed in a conventional manner, there is no way to remove entrapped air from the cartridge. As such, it will be appreciated that filling cartridges in this manner can be difficult and inefficient, often requiring expensive equipment to effectively perform such filling operations, and may still lead to a reduction in the quality of ink cartridges. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, an ink cartridge is provided that avoids or minimizes the problems and difficulties encountered with ink cartridges of the foregoing nature, while promoting the desired simplicity of structure, economy of manufacture, ease of assembly, and maintaining the quality of ink stored and dispensed in association with such ink cartridges. 
     More particularly, in this respect, ink cartridges according to the invention include a housing having a cavity therein for the storage of a quantity of ink. A dispensing port extends through the housing from the cavity such that ink may be dispensed through the port. The housing has a top wall, such as a cover, extending there across and enclosing the cavity. In the present embodiment, the top wall is in the form of a cover and is secured to the housing by welding, bonding or adhesive, for example, forming a fluid-tight seal with the housing. In addition to the dispensing port, the housing may have one or more additional ports extending therethrough placing the cavity in fluid communication with the ambient atmosphere. One of the additional ports, the vacuum port, is fitted with a check valve that permits the flow of fluid through the port in substantially one direction. 
     The check valve is supported on the cartridge adjacent the vacuum port, and permits fluid to flow from the cavity inside the cartridge out through the port without permitting substantial flow of fluid in the reverse direction, that is, flow of fluid into the cavity from the ambient atmosphere. 
     An arrangement of the vacuum port and check valve according to the subject invention includes an elastomeric check valve having a body portion and a valve portion, and a vacuum port having a retaining portion and a fluid-passage portion. The body portion of the check valve is housed in the retaining portion of the vacuum port such that the fluid-passage portion remains substantially unobstructed. The valve portion of the check valve extends from the body portion along the exterior of the housing beyond the fluid-passage portion of the vacuum port and engages an external surface of the housing forming a fluid-tight seal between the valve portion and the external surface. 
     Accordingly, the present invention advantageously provides a cartridge for dispensing ink in which the ink is stored under a reduced pressure relative to the ambient atmosphere, and the cartridge includes a check valve that facilitates removal of air trapped in the cartridge after the filling process. 
     Other advantages of the invention reside in improved print quality and operation, as well as extended shelf life of the ink cartridge. 
     Furthermore, an ink cartridge of the foregoing character is comprised of a minimum number of parts and is structurally simple, thereby promoting and maintaining the economical production of the ink cartridge. 
     Still other benefits and advantages will become apparent to those skilled in the art upon reading and understanding the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional elevation view through on embodiment of an ink cartridge in accordance with the present invention. 
     FIG. 2 is a plan view of the ink cartridge shown from the direction of line  2 — 2  of FIG.  1 . 
     FIG. 3 is an enlarged partial view of the ink cartridge shown in FIG. 1 with the check valve in the closed, sealed position. 
     FIG. 4 is an enlarged, partial view of the ink cartridge shown in FIG. 1 with the check valve shown in the open, unsealed position. 
     FIG. 5 is an enlarged, partial view of the ink cartridge shown in FIG. 1 with the check valve shown in a closed, sealed position and further including a sealing member extending over the check valve. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Referring now in greater detail to the drawings, wherein the showings are for the purpose of illustrating preferred embodiments of the invention only, and not for the purpose of limiting the invention, FIG. 1 illustrates an ink cartridge  10  having a housing  12 , a seal member  14  extending along the exterior of housing  12 , and a check valve  16  supported on housing  12  and between the housing and seal member  14 . 
     Housing  12  includes a bottom wall  18  and side walls  20  extending from bottom wall  18  and defining a cavity  22  therebetween. Extending from bottom wall  18  opposite cavity  22  is a tube-like member or chimney  24 . Extending through chimney  24  from cavity  22  is a dispensing port  26 . Sidewalls  20  of housing  12  terminate at top edge  28 . A cover  30  engages top edge  28  of housing  12  and encloses the cavity  22 . Cover  30  is permanently attached or fused to top edge  28  of housing  12  and a fluid-tight seal is formed between the cover and the housing. It will be appreciated that attachment may be made by any one of a variety of suitable methods, such as welding, bonding or gluing. It will be further appreciated that ink cartridges are generally well known and may including housings having a top wall in a form other than the illustrated cover. 
     In addition to dispensing port  26 , housing  12  includes a fill port  32  and a vacuum port  34 . Fill port  32  may be of any one of a variety of configurations suitable for receiving a fill nozzle for injecting a quantity of ink IK into cavity  22  of housing  12 . Fill port  32  may be closed off or sealed by a plug  36  after the fill operation has been completed. Vacuum port  34  is shown in FIG. 2 as having a keyhole shape that includes a valve-retaining portion  38  and a fluid-passage portion  40 . It will be appreciated that vacuum port  34  may take any one of a variety of shapes or configurations suitable for both retaining check valve  16  and providing a passage for fluid through cover  30  from cavity  22 . Such configurations may include a vacuum port having a plurality of separate passages, one or more of which may be used to retain check valve  16  while others are utilized as a fluid passage. Cover  30  also includes a recess  42  adjacent vacuum port  34  and having an inside peripheral wall  43  and a base wall  44 . In the current embodiment, a seal-engaging surface  46  extends from base wall  44 , and may be integrally formed from the same material as cover  30  or may be formed from a separate or different material and attached to cover  30 . Additionally, it will be appreciated that in other embodiments seal engaging surface  46  may be eliminated, or the surface may be recessed into base wall  44 . It will be further appreciated that seal engaging surface  46  may have a portion having refined surface characteristics for improving engagement with valve portion  50  of check valve  16 , such as a reduced roughness, a reduced amount of contamination or foreign deposits, or a coating extending over the surface. 
     As is more particularly shown in FIGS. 3-5, check valve  16  includes a body portion  48  and a valve portion  50 . Body portion  48  extends into valve-retaining portion  38  of vacuum port  34 . Retaining members  52  extend from body portion  48  and retain check valve  16  in vacuum port  34  due to the outside diameter of retaining members  52  being larger than the inside diameter of valve-retaining portion  38 . It will be appreciated that retaining portion  38  and retaining members  52  may be of any one of a wide variety of configurations suitable for preventing the unintentional removal of check valve  16  from vacuum port  34 . Furthermore, check valve  16  may be formed from any one of a variety of materials. In the embodiment disclosed, check valve  16  is formed from an elastomeric material, such as silicon rubber. 
     Valve portion  50  of check valve  16  extends outwardly from body portion  48  and terminates at an outside peripheral wall  54 . Valve portion  50  of the check valve includes a seal portion  56  and a web portion  58 . In the embodiment shown in FIGS. 3-5, the valve portion of the check valve is annular in shape and seal portion  56  circumferentially extends about valve portion  50  radially inwardly of peripheral wall  54 . Web portion  58  of the valve portion extends from the body portion  48  and connects the seal portion  56  thereto. It will be appreciated that the valve portion may take the form of any one of a variety of shapes or sizes. 
     In the embodiment shown in FIGS. 3-5, seal engaging surface  46  of base wall  44  extends circumferentially about the vacuum port  34 . Seal portion  56  is positioned adjacent surface  46  and includes a sealing surface  60  that contacts the seal-engaging surface  46 . Fluid-passage portion  40  of vacuum port  34  extends radially inwardly of the seal formed between sealing surface  60  of the seal portion and seal-engaging surface  46  of the base wall such that check valve  16  fluidically isolates the vacuum port  34  and cavity  22  from the ambient atmosphere external to ink cartridge  10 . In the present embodiment, the sealing surface  60  is a circumferentially extending curvilinear surface. However, it will be appreciated that sealing surface  60  may take any one of a variety of suitable forms without deviating from the principles of the subject invention. 
     In operation, as shown in FIG. 3, the valve portion is biased toward a closed, sealed position in which the sealing surface  60  engages seal-engaging surface  46  forming a fluid-tight seal therebetween. As shown in FIG. 4, the induction of a reduced-pressure area PL external to ink cartridge  10  adjacent seal member  14  and vacuum port  34  causes the deflection of valve portion  50  due to the differential pressure. The air retained in high-pressure area PH will be removed through fluid-passage portion  40  of vacuum port  44  along the path indicated by arrow AF. Once the cavity has been sufficiently evacuated, the valve portion  50  returns to the closed, sealed position, as shown in FIG. 5, again forming a fluid-tight seal between sealing surface  60  and seal-engaging surface  46 . Once the valve portion  50  has returned to the closed, sealed position, a reduced-pressure area PL, relative to ambient, will exist within cavity  22  of cartridge  10  and be maintained and isolated from the ambient atmosphere PH outside ink cartridge  10  by the seal formed between sealing surface  60  and seal-engaging surface  46 . The flexural properties of the check valve  16  bias valve portion  50  toward the closed, sealed position. Additionally, the differential pressure between the ambient atmosphere outside the ink cartridge and the reduced-pressure area inside cavity  22  of ink cartridge will further bias the valve portion toward the closed, sealed position. To minimize any further chance that fill port  32  or vacuum port  34  will leak and allow the passage of air into cavity  22  or permit ink to evaporate or otherwise leak from the ports, seal member  14  extends across cover  30  of housing  12  to cover these ports. Seal member  14  may be welded, bonded or glued to cover  30 , and may be formed from a material such as a plastic, an elastomer, or a metallic foil that is typically heat sealed to the cover. 
     While considerable emphasis has been placed herein on the structures and structural interrelationships between the features of the embodiment disclosed, it will be appreciated that other embodiments of the invention can be made and that many changes can be made in the embodiments illustrated and described without departing from the principles of the invention. For example, the check valve may be constructed as illustrated in the drawings from other elastomer materials, or the device may be alternately manufactured from other materials such as metal, plastic or a composite material. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely illustrative of the present invention and not as a limitation.