Patents by Inventor Thomas A. Fields

Thomas A. Fields 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: 7639407
    Abstract: Laser beam scan line nonlinearity is compensated for by providing algorithms for generating linearity profiles which are used by a corresponding registration system in an electrophotographic device to determine the placement of Pels across a scan line.
    Type: Grant
    Filed: March 24, 2004
    Date of Patent: December 29, 2009
    Assignee: Lexmark International, Inc.
    Inventors: Cyrus B. Clarke, William P. Corbett, Thomas A. Fields, Christopher D. Jones
  • Patent number: 7403214
    Abstract: The dynamic range of an electrophotographic device may be shifted by calibrating a laser power of a laser source to operate within a first range of power levels during a laser power adjustment operation. At least one laser control parameter is modified after calibrating the laser power so that the laser source is operable within a second range of power levels different from the first range of power levels and a beam emitted by the laser source is controlled within the second range of power levels when the beam is directed towards an image area of a photoconductive surface.
    Type: Grant
    Filed: February 21, 2006
    Date of Patent: July 22, 2008
    Assignee: Lexmark International, Inc.
    Inventors: Thomas A. Fields, Christopher D. Jones, William P. Cook, Cyrus B. Clarke, Jonathan C. Frey
  • Patent number: 7375738
    Abstract: Systems and methods are provided for electronically adjusting an image to compensate for laser beam process direction position errors in an electrophotographic device. Initially, a bow profile is defined that characterizes the process direction position errors of a laser beam across a scan line. The device subsequently reads an image to be printed from a first memory location, performs pixel shifts on select columns thereof based upon the bow profile, and temporarily stores the adjusted image data to a second location of memory. The adjusted image data is then communicated to a printhead of the device.
    Type: Grant
    Filed: March 24, 2004
    Date of Patent: May 20, 2008
    Assignee: Lexmark International, Inc.
    Inventors: William P. Corbett, Thomas A. Fields, Allen P. Johnson, Christopoher D. Jones
  • Patent number: 7349123
    Abstract: Systems and methods are provided for characterizing laser beam process direction position errors in an electrophotographic device. Once the process direction position errors of a given beam laser beam system have been characterized, an image is adjusted or warped prior to being processed by the laser beam system to compensate for laser beam process direction position errors, e.g., bow and skew.
    Type: Grant
    Filed: March 24, 2004
    Date of Patent: March 25, 2008
    Assignee: Lexmark International, Inc.
    Inventors: Cyrus B. Clarke, Thomas A. Fields, Allen P. Johnson, Christopher D. Jones
  • Patent number: 7206012
    Abstract: An optical scanner is provided having a memory device thereon. The memory device may store operational characteristics of the optical scanner or data that characterizes laser beam scan path and/or laser power requirements by each laser of the optical scanner. The memory device may be used to store historical information such as device temperature, cycles of operation and other historical information of components within a corresponding electrophotographic device. Still further, the electrophotographic device to which the optical scanner is installed may write operational data to the memory device, for example, to store a backup of registration and other operational parameters that are typically stored by the controller of the electrophotographic device.
    Type: Grant
    Filed: March 24, 2004
    Date of Patent: April 17, 2007
    Assignee: Lexmark International, Inc.
    Inventors: William P. Cook, Thomas A. Fields, Allen P. Johnson, Christopher D. Jones, Gregory L. Ream
  • Patent number: 7123282
    Abstract: A method of minimizing visual artifacts resulting from a laser scan process in an electrophotographic machine, the electrophotographic machine including a photoconductive device having an image forming surface. The method including the steps of obtaining correction data relative to a bowed image and offsetting at least a portion of non-bowed image data dependent upon the correction data, and additionally dependent upon halftone cell growth of a halftone cell.
    Type: Grant
    Filed: January 14, 2004
    Date of Patent: October 17, 2006
    Assignee: Lexmark International, Inc.
    Inventors: Thomas A. Fields, Craig E. Hadady, Christopher D. Jones, Philip J. Heink
  • Patent number: 4205211
    Abstract: An improved apparatus for alloying a surface of a workpiece of the type in which an electrode, formed of the alloying material, is connected to a pulse generating machine which creates repetitive spark discharges between the electrode and the workpiece when the electrode is in engagement with the workpiece, the improvement being a safety circuit which prevents energization of the electrode until it is engaged with the workpiece.
    Type: Grant
    Filed: November 23, 1977
    Date of Patent: May 27, 1980
    Assignees: Alloying Surfaces, Inc., Richard A. Serlin
    Inventors: Richard A. Serlin, Thomas A. Field