Patents by Inventor Palitha Wickramanayake

Palitha Wickramanayake has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6905729
    Abstract: Methods of preparing media sheets for ink-jet printing applications are provided. In one embodiment, the media sheets can be prepared by dispersing or dissolving inorganic porous particulates and an active ligand-containing organosilane reagent in water; reacting the inorganic porous particulates and the active ligand-containing organosilane reagent to form media coating composition; and applying the media coating composition to a media substrate. In another embodiment, the media sheets can be prepared by coating a media substrate with inorganic porous particulates; dispersing or dissolving an active ligand-containing organosilane reagent in water to form a liquid coating composition; and applying the liquid coating composition to the inorganic porous particulates that has previously been coated on the substrate.
    Type: Grant
    Filed: October 25, 2002
    Date of Patent: June 14, 2005
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventor: Palitha Wickramanayake
  • Publication number: 20050084630
    Abstract: Systems and methods for producing permanent ink-jet images are provided. In one embodiment, a system comprises a media substrate coated with a porous media coating, wherein the porous media coating comprises inorganic porous particulates, and wherein at least a portion of the inorganic porous particulates have a first reactive group covalently attached thereto. The system further includes an ink-jet ink containing a dye, wherein the dye comprises a second reactive group, and wherein the first reactive group and the second reactive group are configured to react with one another upon contact to form a covalent bond.
    Type: Application
    Filed: October 16, 2003
    Publication date: April 21, 2005
    Inventors: Vladek Kasperchik, Palitha Wickramanayake, James Shields, Gary Ungefug
  • Publication number: 20040219311
    Abstract: Silica-based, chemically-bonded porous coatings, synthesized via the reaction of organo silanes with silica, are used as coatings for inkjet image printing. Silica is used as the base material in all cases, due to its favorable chemical properties of the surface, and the favorable pore structure. The silane-silica reaction product substantially retains the original pore structure of the pre-reacted silica. The disclosed embodiments solve the problems in the prior art in that any catalytic activity of the silica surface towards image fade is eliminated by the chemical modification of silica. This improves the image fade and humid fastness properties of the coating.
    Type: Application
    Filed: May 25, 2004
    Publication date: November 4, 2004
    Inventors: Palitha Wickramanayake, James P. Shields
  • Publication number: 20040209017
    Abstract: A method for the preparation of a print medium that helps to reduce unwanted print artifacts such as bronzing, gloss non-uniformity, print smudging, and coalescence. Specifically, a method can comprise a step of preparing a coating composition with an acidic pH and a step of coating a media substrate with the coating composition to form an ink-receiving layer thereon. The coating composition can comprise a dispersion of inorganic particulates, a polymeric binder, and a weak base comprising a salt of an alkali metal and a weak acid. The weak base generates gas bubbles in the coating composition as a result of the acidic pH.
    Type: Application
    Filed: February 6, 2004
    Publication date: October 21, 2004
    Inventors: Peter C. Zahrobsky, Matthew Thornberry, Palitha Wickramanayake, Urs Fuerholz, Linda C. Uhlir-Tsang, Eric L. Burch
  • Publication number: 20040209015
    Abstract: An additive used in a print medium to reduce bronzing. The additive increases a pH of the print medium. The additive is an organic base or an inorganic base. The additive reduces bronzing of an image printed with a dye-based inkjet ink.
    Type: Application
    Filed: April 15, 2003
    Publication date: October 21, 2004
    Inventors: Palitha Wickramanayake, Matthew Thornberry
  • Patent number: 6805736
    Abstract: Ink sets that are particularly suitable for inkjet printing over a large range of uncoated papers, have reduced bleed between color and black inks, and include black and color inks that are mutually compatible in pens. The ink sets include at least one pigment-based black ink having cationic and anionic dispersant groups, and at least one color dye or pigment that interacts with the black ink when printed on a receiving medium. The black pigment is self-dispersed and is dual treated with cationic and anionic dispersant groups. When printed onto an alkaline medium, the black pigment will carry a net negative charge that will interact with the positively charged color dyes and/or pigments and, thus, be bleed arrested. When printed onto an acidic medium, the black pigment will have a positive charge, will interact with the negatively charged color dyes and/or pigments, and thus be bleed arrested.
    Type: Grant
    Filed: January 2, 2003
    Date of Patent: October 19, 2004
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventor: Palitha Wickramanayake
  • Publication number: 20040129171
    Abstract: Ink sets that are particularly suitable for inkjet printing over a large range of uncoated papers, have reduced bleed between color and black inks, and include black and color inks that are mutually compatible in pens. The ink sets include at least one pigment-based black ink having cationic and anionic dispersant groups, and at least one color dye or pigment that interacts with the black ink when printed on a receiving medium. The black pigment is self-dispersed and is dual treated with cationic and anionic dispersant groups. When printed onto an alkaline medium, the black pigment will carry a net negative charge that will interact with the positively charged color dyes and/or pigments and, thus, be bleed arrested. When printed onto an acidic medium, the black pigment will have a positive charge, will interact with the negatively charged color dyes and/or pigments, and thus be bleed arrested.
    Type: Application
    Filed: January 2, 2003
    Publication date: July 8, 2004
    Inventor: Palitha Wickramanayake
  • Publication number: 20040081772
    Abstract: Methods of preparing media sheets for ink-jet printing applications are provided. In one embodiment, the media sheets can be prepared by dispersing or dissolving inorganic porous particulates and an active ligand-containing organosilane reagent in water; reacting the inorganic porous particulates and the active ligand-containing organosilane reagent to form media coating composition; and applying the media coating composition to a media substrate. In another embodiment, the media sheets can be prepared by coating a media substrate with inorganic porous particulates; dispersing or dissolving an active ligand-containing organosilane reagent in water to form a liquid coating composition; and applying the liquid coating composition to the inorganic porous particulates that has previously been coated on the substrate.
    Type: Application
    Filed: October 25, 2002
    Publication date: April 29, 2004
    Inventor: Palitha Wickramanayake
  • Publication number: 20040022946
    Abstract: Ceramic pigment-based, chemically-modified porous coatings can be used for enhancing image permanence of ink-jet image printing. Specifically, a porous coated media sheet, comprising a media substrate, having a porous coating coated thereon comprising a modified ceramic pigment including a fixer group and a stabilizer group, each covalently attached to the ceramic pigment is disclosed. Additionally, a method and system for preparing permanent ink-jet images is also provided.
    Type: Application
    Filed: July 30, 2003
    Publication date: February 5, 2004
    Inventors: Kent D. Vincent, Sivapackia Ganapathiappan, Sean Xiao-An Zhang, Palitha Wickramanayake
  • Publication number: 20030198801
    Abstract: The present invention is drawn to a coated substrate for ink-jet ink printing comprising a substrate, having coated thereon, a porous coating, wherein the porous coating comprises silica covalently attached to a chelating agent, an ultraviolet blocker, and/or a hindered amine light stabilizer. In one embodiment, the chelating agent, ultraviolet blocker, and/or hindered amine light stabilizer can be substantially homogenously distributed on the silica.
    Type: Application
    Filed: April 10, 2002
    Publication date: October 23, 2003
    Inventors: Palitha Wickramanayake, Larrie A. Deardurff, James P. Shields
  • Publication number: 20030175451
    Abstract: Silica-based, chemically-bonded porous coatings, synthesized via the reaction of organo silanes with silica, are used as coatings for inkjet image printing. Silica is used as the base material in all cases, due to its favorable chemical properties of the surface, and the favorable pore structure. The silane-silica reaction product substantially retains the original pore structure of the pre-reacted silica. The disclosed embodiments solve the problems in the prior art in that any catalytic activity of the silica surface towards image fade is eliminated by the chemical modification of silica. This improves the image fade and humid fastness properties of the coating.
    Type: Application
    Filed: March 12, 2002
    Publication date: September 18, 2003
    Inventors: Palitha Wickramanayake, James P. Shields
  • Patent number: 6300391
    Abstract: The ink set of this invention comprises at least two inks, one of which contains a pH sensitive polymer, a glycol ether, and preferably a self-dispersing pigment colorant. A second ink is provided which comprises incompatible inorganic or organic salts or has an appropriate pH. The polymer precipitates onto a medium upon contact with the second ink, thereby providing improved dry time as well as bleed and halo control.
    Type: Grant
    Filed: October 1, 1999
    Date of Patent: October 9, 2001
    Assignee: Hewlett-Packard Company
    Inventors: Dennis P Parazak, Palitha Wickramanayake
  • Publication number: 20010018472
    Abstract: The ink set of this invention comprises at least two inks, one of which contains a pH sensitive polymer, a glycol ether, and preferably a self-dispersing pigment colorant. A second ink is provided which comprises incompatible inorganic or organic salts or has an appropriate pH. The polymer precipitates onto a medium upon contact with the second ink, thereby providing improved dry time as well as bleed and halo control.
    Type: Application
    Filed: October 1, 1999
    Publication date: August 30, 2001
    Applicant: HEWLETT-PACKARD COMPANY
    Inventors: DENNIS P. PARAZAK, PALITHA WICKRAMANAYAKE
  • Patent number: 6036759
    Abstract: The ink set of this invention comprises an anionic black pigmented ink and at least one color ink containing a dye or pigment colorant. The performance of these ink sets is improved by the addition of specific cationic surfactant or cationic (quaternary) salts which interact with the anionic black pigmented ink to provide improved black to color bleed control.
    Type: Grant
    Filed: April 30, 1998
    Date of Patent: March 14, 2000
    Assignee: Hewlett-Packard Company
    Inventors: Palitha Wickramanayake, Raymond J. Adamic
  • Patent number: 6019827
    Abstract: An aqueous microemulsion-based ink-jet ink composition is provided which employs a second organic solvent that is miscible with both the discontinuous and the continuous phase. Specifically, the ink-jet ink composition of the present invention comprises at least one dye; and a microemulsion comprising at least one high boiling water-insoluble organic compound, at least a second high boiling compound miscible with both aqueous and organic phases, at least one amphiphile, and water, wherein the amphiphile is present in an amount sufficient to solubilize the water-insoluble organic compound.
    Type: Grant
    Filed: July 15, 1997
    Date of Patent: February 1, 2000
    Assignee: Hewlett-Packard Company
    Inventors: Palitha Wickramanayake, Dennis P. Parazak
  • Patent number: 5713989
    Abstract: Bleed control and fast dry times are achieved in aqueous pigment dispersion-based ink-jet ink compositions by formulating the ink compositions to comprise at least one aqueous pigment dispersion and a microemulsion comprising at least one water-insoluble organic compound, at least one hydrotropic amphiphile, and water. The hydrotropic amphiphile is present in the microemulsion in an amount sufficient to solubilize the water-insoluble organic compound.
    Type: Grant
    Filed: October 29, 1996
    Date of Patent: February 3, 1998
    Assignee: Hewlett-Packard Company
    Inventors: Palitha Wickramanayake, Dennis P. Parazak
  • Patent number: 5565022
    Abstract: Ink-jet ink compositions are provided which exhibit fast dry times and bleed-free prints when printed onto a print medium so that the throughput of an ink-jet printer may be increased. The ink compositions of the invention comprise (a) at least one dye; (b) at least one high-boiling, water-insoluble organic compound; (c) at least one amphiphile; and (d) water. The dye may be either water-soluble or water-insoluble and the high boiling organic compound has a vapor pressure low enough such that only water evaporates from the ink during normal printing operations. The amphiphile is present in an amount sufficient to solubilize the water-insoluble organic compound in the water. Preferably, the amphiphile belongs to a class of compounds known as hydrotropes.
    Type: Grant
    Filed: September 14, 1995
    Date of Patent: October 15, 1996
    Assignee: Hewlett-Packard Company
    Inventor: Palitha Wickramanayake
  • Patent number: 5531816
    Abstract: Bleed control and fast dry times are achieved in pigment-based ink-jet ink compositions by formulating the ink compositions to include at least one appropriately modified pigment in a water-insoluble organic compound, which is microemulsified with an amphiphile and water. By employing a vehicle formulated in accordance with the invention, the present pigment-based ink-jet ink compositions are bleed-free and fast-drying and exhibit the inherent waterfastness of pigments. Moreover, the use of a modified pigment improves print quality by passivating the pigment particles to eliminate agglomerations between the particles and by providing pigment particles of substantially uniform size, thereby yielding more uniform thickness and coverage on a print medium. In short, pigment-based ink-jet ink compositions formulated in accordance with the invention offer the best qualities of pigments as colorants while reducing or eliminating the problems conventionally associated therewith.
    Type: Grant
    Filed: September 14, 1995
    Date of Patent: July 2, 1996
    Assignee: Hewlett-Packard Company
    Inventor: Palitha Wickramanayake
  • Patent number: 5342440
    Abstract: Water-insoluble black dyes are formulated in a micro-emulsion-based ink. When printed adjacent to color inks (yellow, magenta, cyan) containing water-soluble dyes, bleed does not occur between the black and the color dyes.
    Type: Grant
    Filed: October 26, 1992
    Date of Patent: August 30, 1994
    Assignee: Hewlett-Packard Corporation
    Inventor: Palitha Wickramanayake
  • Patent number: 5226957
    Abstract: Water-insoluble dyes are formulated in a microemulsion-based ink, which have true waterfastness, are non-threading, and are bleed-alleviated. The ink-jet inks have a formula comprising: (a) about 0.05 to 0.75 wt % of a high molecular weight colloid; (b) about 0.1 to 40 wt % of at least two surfactants, comprising at least one surfactant and at least one co-surfactant; (c) about 0.5 to 20 wt % of at least one co-solvent; (d) about 0.1 to 5 wt % of at least one water-insoluble dye; (e) about 0.1 to 20 wt % of an oil; and (f) the balance water. The inks of the invention form a stable microemulsion, which results in bleed alleviation, excellent line definition without threading, and excellent print quality.
    Type: Grant
    Filed: March 17, 1992
    Date of Patent: July 13, 1993
    Assignee: Hewlett-Packard Company
    Inventors: Palitha Wickramanayake, John R. Moffatt