Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-04-24
2004-01-13
Vo, Anh T.N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S085000
Reexamination Certificate
active
06676252
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to inkjet printers and methods and more particularly relates to an inkjet printer cartridge and method of assembling same, the cartridge being adapted to avoid chemical interaction between ink stored in the cartridge and a seal sealing the cartridge.
An inkjet printer produces images on a recording medium by ejecting ink droplets onto the recording medium in an image-wise fashion. The advantages of non-impact, low-noise, low energy use, and low cost operation in addition to the ability of the printer to print on plain paper are largely responsible for the wide acceptance of ink jet printers in the marketplace.
More specifically, an ink jet printer comprises an inkjet printer cartridge that includes a plurality of ink ejection chambers and a plurality of ink ejection orifices in communication with respective ones of the ink ejection chambers. At every orifice a heat actuated ink ejector, such as found in thermal ink jet printers, is used to produce an ink droplet. In such thermal ink jet printers, a heater locally heats the ink body and a quantity of the ink phase changes into a gaseous steam bubble. The steam bubble raises the internal ink pressure sufficiently for an ink droplet to be expelled through the ink ejection orifice and toward the recording medium. Thermal inkjet printers are well-known and are discussed, for example, in U.S. Pat. Nos. 4,500,895 to Buck, et al.; U.S. Pat. No. 4,794,409 to Cowger, et al.; U.S. Pat. No. 4,771,295 to Baker, et al.; U.S. Pat. No. 5,278,584 to Keefe, et al.; and the Hewlett-Packard Journal, Vol. 39, No. 4 (August 1988), the disclosures of which are all hereby incorporated by reference.
The inkjet printer cartridge itself may be a carriage mounted printer cartridge that reciprocates transversely with respect to the recording medium (i.e., across the width of the recording medium) as a controller connected to the printer cartridge selectively fires individual ones of the ink ejection chambers. Each time the printer cartridge traverses the recording medium, a swath of information is printed on the recording medium. After printing the swath of information, the printer advances the recording medium the width of the swath and the printer cartridge prints another swath of information in the manner mentioned immediately hereinabove. This process is repeated until the desired image is printed on the recording medium. Alternatively, the printer cartridge may be a page-width printer cartridge that is stationary and that has a length sufficient to print across the width of the recording medium. In this case, the recording medium is moved continually and normal to the stationary printer cartridge during the printing process.
Inks useable with thermal inkjet printers, whether those printers have carnage-mounted or page-width printer cartridges, are specially formulated to provide suitable images on the recording medium. Such inks typically include a colorant, such as a pigment or dye, and an aqueous liquid, such as water, and/or a low vapor pressure solvent. More specifically, the ink is a liquid composition comprising a solvent or carrier liquid, dyes or pigments, humectants, organic solvents, detergents, thickeners, preservatives and other components. Moreover, the solvent or carrier liquid may be water alone or water mixed with water miscible solvents such as polyhydric alcohols, or organic solvents. Various liquid ink compositions are disclosed, for example, by U.S. Pat. No. 4,381,946 titled “Ink Composition For Ink-Jet Recording” issued May 3, 1983 in the name of Masafumi Uehara, et al.
The printer cartridge includes a central cavity that is filled with ink of a predetermined color during manufacture of the cartridge. Composition of the cartridge walls may comprise polyethylene naphthalate, which is known to be resistant to corrosive effects of ink materials. The terminology “corrosive effect” means chemical deterioration when the ink comes in contact with a material. The printer cartridge also includes an inlet aperture in communication with the cavity for allowing the cavity to be filled with the ink. Disposed in the inlet aperture is an elastomeric seal that seals the aperture, so that the ink does not exit the cavity through the aperture after being filled with ink. The composition of the elastomeric seal may comprise constituents, such as silicone rubber with zinc oxide and stearic acid as additives. An exemplary inkjet printer cartridge is disclosed more fully, for example, by U.S. Pat. No. 6,113,229 titled “Interchangeable Fluid Interconnect Attachment And Interface” issued Sept. 5, 2000, in the name of Max Stephen Gunther, et al. and assigned to the assignee of the present invention, the disclosure of which is hereby incorporated by reference.
As a step in manufacture of the cartridge, an adhesive tape is placed over the exterior of the ink ejection orifices to prevent ink leaking from the orifices during packaging, shipment and storage of the newly manufactured cartridge. The composition of the adhesive tape exposed to the ink adjacent to the ink ejection orifice may comprise zinc stearate as a constituent. After manufacture, the cartridge is packaged and typically shipped to a retailer or distributor of such cartridges whereupon the cartridge may be stored for a period of time, such as several months, prior to delivery to an end user of the cartridge. Of course, before placing the cartridge in the printer carriage, the end user manually removes the adhesive tape covering the ink ejection orifices, so that ink can be ejected from the cartridge during the printing process.
During printing, the ink in the cartridge cavity is gradually depleted. When sufficiently depleted, the cartridge is discarded and replaced with another cartridge containing ink. However, the heat actuated ink ejector typically remains operable even after depletion of the ink in the cartridge. In other words, the heat actuated ink ejector has useful operational life remaining although the ink in the cartridge is depleted. This has given rise to an after-market in which used cartridges are refilled, resold and re-used. This has also given rise to development of inkjet printer systems using an external ink supply reservoir connectable to the depleted cartridge for refilling the cartridge by means of a hollow ink supply needle. The needle is capable of piercing the seal to inject ink into the cavity formed in the cartridge.
However, it has been observed that during storage of the newly manufactured ink cartridge, the ink in the cavity may chemically interact with the zinc oxide and stearic acid constituents of the seal that seals the cartridge cavity. Over time, the ink leaches the zinc oxide and stearic acid from the seal to form zinc stearate crystals in the ink in the cavity. These zinc stearate crystals then migrate to the ink ejection orifices to clog or block the ink ejection orifices. However, the precise mechanism by which the zinc stearate crystals form is not completely understood. In this regard, zinc stearate may instead remain in solution (i.e., dissolved) in the ink in the cavity and only form crystals on the adhesive tape covering the orifices. In this instance, the crystals may accumulate in the orifices to clog or block the orifices. In any event, it is undesirable to block the ink ejection orifices. It is undesirable to block the ink ejection orifices because blocking the ink ejection orifices interferes with proper ejection of ink drops during printing. Thus, it would be desirable to avoid chemical interaction between the ink and the seal during shipment and prolonged storage. Consequently, a problem in the art is chemical interaction between the ink and the seal.
Therefore, what is needed is an inkjet printer cartridge adapted to avoid chemical interaction between ink stored in the cartridge and a seal sealing the cartridge.
SUMMARY OF THE INVENTION
In its broad form, the present invention comprises a printer ink cartridge comprising a shell defining a cavity and a port; a seal spanning the p
Bilotta Michael F
Cruz-Uribe Antonio
Stevens Walter S.
Vo Anh T.N.
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