Patents by Inventor Peter G. Hofstra
Peter G. Hofstra 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).
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Patent number: 7372436Abstract: The present invention introduces a novel design for active matrix displays, utilizing both organic light-emitting diode (OLED) and thin-film electroluminescent technologies. In a first aspect there is provided a top-emitting OLED, including an optical interference contrast-enhancing stack that is placed on the top of the driving thin-film transistor, and which extendes to the entire pixel area to cover the reflecting parts of the pixel. In a second aspect, there is provided a bottom-emitting OIED wherein an optical interference contrast-enhancing stack is placed right under the driving thin-film transistor and, separately between the organic stack and the top electrode, typically a cathode. The optical interference contrast-enhancing stack suppresses light reflection from the thin-film transistor and the upper electrode.Type: GrantFiled: June 11, 2003Date of Patent: May 13, 2008Assignee: Luxell Technologies, Inc.Inventors: Alexey N. Krasnov, Richard P. Wood, David J. Johnson, Peter G. Hofstra
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Patent number: 6784602Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: GrantFiled: October 25, 2001Date of Patent: August 31, 2004Assignee: Luxell Technologies Inc.Inventors: Peter G. Hofstra, Alexey Krasnov
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Publication number: 20040052931Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: ApplicationFiled: April 14, 2003Publication date: March 18, 2004Inventors: Peter G. Hofstra, Alexey N. Krasnov
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Publication number: 20030214230Abstract: The present invention provides an electroluminescent device having a dark layer for reducing at least a portion of ambient light incident on the display. In one bottom emitting device embodiment, the dark layer is placed between the emitting layer and a reflective rear cathode. The dark layer comprises a partially reflective layer, an absorptive-transmissive layer, and a reflective layer.Type: ApplicationFiled: March 10, 2003Publication date: November 20, 2003Inventors: Richard P. Wood, Peter G. Hofstra, David J. Johnson, Alexey N. Krasnov
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Publication number: 20030127971Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: ApplicationFiled: October 25, 2001Publication date: July 10, 2003Inventors: Peter G. Hofstra, Alexey Krasnov
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Patent number: 6551651Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: GrantFiled: October 25, 2001Date of Patent: April 22, 2003Assignee: Luxell Technologies, Inc.Inventors: Peter G. Hofstra, Alexey Krasnov
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Publication number: 20020153834Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: ApplicationFiled: October 25, 2001Publication date: October 24, 2002Inventors: Peter G. Hofstra, Alexey Krasnov
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Patent number: 6411019Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: GrantFiled: July 27, 1999Date of Patent: June 25, 2002Assignee: Luxell Technologies Inc.Inventors: Peter G. Hofstra, Alexey Krasnov
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Publication number: 20020039871Abstract: The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.Type: ApplicationFiled: October 25, 2001Publication date: April 4, 2002Inventors: Peter G. Hofstra, Alexey Krasnov
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Patent number: 5378574Abstract: Ink jet inks and liquid developers are disclosed which contain colored particles comprising hydrophilic silica particles, to the surfaces of which dyes are covalently bonded through silane coupling agents. The ink jet inks generally comprise a liquid medium and a plurality of the colored silica particles. The liquid developers generally comprise a liquid medium, a resin, a plurality of the colored silica particles, and a charge control agent. The particles are prepared by a process which comprises reacting hydrophilic silica particles with a silane coupling agent in the absence of water to form particles having covalently attached thereto coupling agents, followed by reacting a dye with the coupling agent attached to the silica particles.Type: GrantFiled: June 23, 1989Date of Patent: January 3, 1995Assignee: Xerox CorporationInventors: Francoise M. Winnik, Barkev Keoshkerian, Raymond W. Wong, Stephan Drappel, Melvin D. Crocher, James D. Mayo, Peter G. Hofstra
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Patent number: 5100471Abstract: An aqueous ink jet composition comprised of a solvent and colored particles comprised of a polymeric core and a silica shell onto which dyes are covalently bonded.Type: GrantFiled: June 27, 1990Date of Patent: March 31, 1992Assignee: Xerox CorporationInventors: Francoise M. Winnik, Peter G. Hofstra