Patents by Inventor James J. Appel

James J. Appel 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: 5461412
    Abstract: In an optical output device in which a beam of light is generated, focused to a spot, and scanned across an image plane to form a scan line, scan line curvature caused by offset between at least one light source and an optical axis of the device is corrected. The invention may be embodied in an apparatus that includes a light source capable of emitting the beam of light at a selected one of at least two selectable wavelengths and a deflecting element such as a prism that refracts the beam of light by an amount that depends on the wavelength of the beam.
    Type: Grant
    Filed: July 23, 1993
    Date of Patent: October 24, 1995
    Assignee: Xerox Corporation
    Inventors: Thomas L. Paoli, James J. Appel
  • Patent number: 5444239
    Abstract: A fiber optic system is used in a laser ROS scanning system to generate a start of scan signal. In one embodiment, a single optical fiber is positioned at the beginning of a scan line sweep. The fiber transmits a portion of a scan beam energy to a photodetector located on a local electronics board. The photodiode generates an output signal which is sent as an input to a high speed comparator. A second input to the comparator is a divided down and delayed analog of the photodetector output signal. The comparator compares the two voltage wave forms and generates electrical signals at the precise time the two wave forms intersect or crossover. The comparator output is used to initiate the SOS signal of a gas or laser diode ROS.
    Type: Grant
    Filed: March 25, 1994
    Date of Patent: August 22, 1995
    Assignee: Xerox Corporation
    Inventors: Aron Nacman, James J. Appel, Andrew M. Strauch
  • Patent number: 5381259
    Abstract: In an overfilled ROS polygon system, the total optical path length is minimized by focusing modulated laser beams onto the polygon facets in the cross scan direction by placing a single cylindrical lens between the laser diode and a collimator lens. The combined cross scan power of the cylinder lens and the collimator lens provides the cross scan focusing at the required high magnification.
    Type: Grant
    Filed: October 14, 1993
    Date of Patent: January 10, 1995
    Assignee: Xerox Corporation
    Inventor: James J. Appel
  • Patent number: 5377036
    Abstract: In an overfilled ROS polygon architecture, stray reflection from facets adjacent the completely filled (illuminated) facet are neutralized by placing an optical isolator in the path of the unwanted stray reflections. In a first embodiment, the isolator comprises a linear polarizer and a quarter wave plate. In a second embodiment, the isolator comprises a liquid crystal quarter wave plate and a cholesteric liquid crystal cell.
    Type: Grant
    Filed: December 10, 1992
    Date of Patent: December 27, 1994
    Assignee: Xerox Corporation
    Inventors: James J. Appel, John A. Durbin, John R. Andrews
  • Patent number: 5371526
    Abstract: A raster output scanner (ROS) laser diode architecture produces plurality of laser beams, having dissimilar wavelengths and dissimilar polarizations which are passed through wavelength and polarization discriminating optics to alternately pass or reflect the beams that have been scanned by a single polygon mirror. Polarization of the beams is accomplished via post emission polarizers, such as, for example, half-wave plates. These separated beams then expose their associated photo-receptors, for example, of a multistation printer, with a rasterized image that is subsequently transferred to a support medium such as plain paper, and developed into an image.
    Type: Grant
    Filed: September 22, 1992
    Date of Patent: December 6, 1994
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Thomas L. Paoli
  • Patent number: 5341158
    Abstract: A raster output scanner (ROS) laser diode architecture enables a plurality of laser diodes, which produce light beams at separated wavelengths, to be spaced a convenient distance apart for a multistation printer, by arranging the diodes in a line that is parallel to the fast scan direction of the ROS. Wavelength discriminating optics are used to alternately separate and reflect the light beams reflected from a single ROS polygon mirror. These separated and reflected beams then expose their associated photoreceptors with a rasterized image that is subsequently transferred to a support medium such as plain paper and developed into an image.
    Type: Grant
    Filed: September 22, 1992
    Date of Patent: August 23, 1994
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Thomas L. Paoli, Tibor Fisli
  • Patent number: 5313291
    Abstract: A color correction method is provided for an electronic printing system that results in a color print that is made as close as possible to what an operator actually observes on a monitor screen (What you see is what you get). The printing system includes a computer, a color printer, and a color monitor.A calibration is automatically performed by the system's computer through the use of calibration software, a series of test patterns stored in the computer memory, a monitor calibrating device, and a scanner equipped with color trichromatic measurement capabilities.
    Type: Grant
    Filed: November 25, 1991
    Date of Patent: May 17, 1994
    Assignee: Xerox Corporation
    Inventors: James J. Appel, John A. Durbin, Richard F. Lehman
  • Patent number: 5311536
    Abstract: Nonmonolithic laser arrays having a plurality of lasing elements mounted on protruding members of a stacked support which includes spacers between the protruding members. The protruding members and spacers are comprised of thermally conductive, but electrically insulative material such as BeO. The conductive layers on the spacers and protruding members assist in providing electrical contact to the lasing elements. The stacked support accurately locates and separates the lasing elements and enables low thermal and electrical crosstalk between the lasing elements.
    Type: Grant
    Filed: July 23, 1993
    Date of Patent: May 10, 1994
    Assignee: Xerox Corporation
    Inventors: Thomas L. Paoli, James J. Appel
  • Patent number: 5287125
    Abstract: Compensation for process direction photoreceptor motion in a Raster Output Scan system is provided by moving the cylinder lens located between the laser source and a rotating spot scanning mechanism, e.g., a polygon. The cylinder lens is moved in the process direction in response to error signals generated by a SOS detector and timing marks on the photoreceptor drum surface, or an encoder on the drum shaft. The lens movement is obtained by sending motion error signals to a piezoelectric actuator which increases in length to impart the desired motion to the cylinder lens.
    Type: Grant
    Filed: August 5, 1991
    Date of Patent: February 15, 1994
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Kenneth R. Ossman
  • Patent number: 5278400
    Abstract: A method and apparatus for applying coded data to a substrate and decoding the data in which the data are encoded in cells having a determined number of pixels. The pixels are coded, preferably by binary printing, in accordance with the number of coded pixels and not their position. In decoding of the cells, the gray scale levels of the pixels are sensed, and converted to digital signals. The digital signals are summed, for all of the pixels of the cell, and compared with multiple threshold levels in order to recover the data.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: January 11, 1994
    Inventor: James J. Appel
  • Patent number: 5270849
    Abstract: In an overfilled ROS polygon architecture, stray reflection from facets adjacent the completely filled (illuminated) facet are prevented from affecting the scan line images by aligning the optical axis of the pre-polygon and post-polygon optical components at an optimum angle .phi.' so that the stray light reflections at the photoreceptor occur only at non-image forming scan times (outside the image scan time). The optimum angle .phi.' is expressed by the relationship .phi.'=2(.OMEGA..+-.1/2.theta.) where .OMEGA. is given by the expression 360/X, X being the number of scanning facets, and .theta. being the scanning angle.
    Type: Grant
    Filed: December 10, 1992
    Date of Patent: December 14, 1993
    Assignee: Xerox Corporation
    Inventors: Edward C. Bock, James J. Appel
  • Patent number: 5264869
    Abstract: Spot registration or position in an optical output device, such as a raster output scanner (ROS), may be controlled in a slow, or process, scan direction by interposing in the image path an electro-optic element whose angular dispersion varies for a given wavelength as a function of the electrical bias applied to it. By orienting the electro-optic element such that dispersion control is perpendicular to the fast or line scan direction of the ROS, varying the electrical bias applied to it varies the dispersion in the slow scan direction. The electro-optic element may be, for example, a prism of AlGaAs. Bias applied to the electro-optic element may be in response to the output of a means for detecting and quantifying such positional errors and/or in response to predetermined correction information output from a processor controlled memory unit or the like. Spot position for single or multiple beam optical output devices may be achieved.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: November 23, 1993
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Thomas L. Paoli
  • Patent number: 5212381
    Abstract: A method of slow, or process, scan direction spot registration or position control in an optical output device, such as a raster output scanner (ROS), may be facilitated by interposing in the image path an electro-optic element whose angular dispersion varies for a given wavelength as a function of the electrical bias applied to it. By orienting the electro-optic element such that dispersion control is perpendicular to the fast or line scan direction of the ROS, varying the electrical bias applied to it varies the dispersion in the slow scan direction. The electro-optic element may be, for example, a prism of AlGaAs. Bias applied to the electro-optic element may be in response to the output of a means for detecting and quantifying such positional errors and/or in response to predetermined correction information output from a processor controlled memory unit or the like. Spot position for single or multiple beam optical output device may be achieved.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: May 18, 1993
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Thomas L. Paoli
  • Patent number: 5208456
    Abstract: In an optical output device wherein a beam of light is generated and focused to a spot upon an image plane, such as a photoreceptor in a xerographic printing apparatus, an apparatus for controlling the position of the spot in the slow scan direction of the image plane including a light source capable of emitting the beam of light at a selected one of at least two selectable wavelengths and beam deflecting means for deflecting the beam of light an amount which depends on the wavelength of the beam of light, the amount of deflection determining the position of the spot in the slow scan direction on the image plane. The light source may be of the solid state laser type, and may emit a plurality of beams of light the spots from which may be individually or together selectively positioned in the slow scan direction on the image plane. The beam deflecting element may be a semiconductor prism, for example of AlGaAs, and have a controllable bias applied thereto to allow further control of spot positioning.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: May 4, 1993
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Thomas L. Paoli
  • Patent number: 5204523
    Abstract: In an optical output device wherein a beam of light is generated and focused to a spot upon an image plane, such as a photoreceptor in a xerographic printing apparatus, an method for controlling the position of the spot in the slow scan direction of the image plane including the steps of generating a beam of light, deflecting the beam of light by way of an optical beam deflecting elements such that the optical beam deflecting element deflects the path of the beam of light by an amount that is determined by the wavelength of the light beam, and varying the wavelength of the beam of light such that the amount that the beam of light is deflected by the optical beam deflecting element is varied to achieve control of the position of the spot at which the beam of light is incident on the image plane in the slow scan direction.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: April 20, 1993
    Assignee: Xerox Corporation
    Inventors: James J. Appel, Thomas L. Paoli
  • Patent number: 5153768
    Abstract: A multiple diode laser ROS scanning system is modified to eliminate the need for buffering scan lines so that they can be brought into the required adjacent lines at a photosensitive surface. The wavelength of the diode outputs are selected such that each diode differs from the other within a selected range. The beams are collimated and directed through a dispersive element such as a prism which is positioned so as to cause the beams to converge towards each other. After reflection from a reflective facet surface of a polygon, the beams are swept across the surface of an image media as adjacent scan lines.
    Type: Grant
    Filed: February 26, 1991
    Date of Patent: October 6, 1992
    Assignee: Xerox Corporation
    Inventor: James J. Appel
  • Patent number: 5140605
    Abstract: A diode laser structure is thermally stabilized by passing current through heater strips along the sides of the diode laser cavity. The thermally stabilized diode laser structure comprises a first confinement layer and a substrate of one conductivity type, an active layer, a second confinement layer and a contact layer of an opposing conductivity type. Disordered regions extend from the contact layer through to the first confinement layer defining diode laser cavities. Resistive regions are formed within the disordered regions. Individual contacts on the contact layer aligned with each diode laser cavity inject current through the diode laser cavity to the contact on the substrate causing emission of coherent light through the edge of the diode laser structure. Individual contacts on the contact layer aligned with resistive region inject current through the resistive region to the contact on the substrate causing generation of heat.
    Type: Grant
    Filed: June 27, 1991
    Date of Patent: August 18, 1992
    Assignee: Xerox Corporation
    Inventors: Thomas L. Paoli, Kenneth R. Ossman, James J. Appel
  • Patent number: 5113202
    Abstract: A single pass highlight color printing system is enabled by utilizing the disparity between the on-time of a printing system and the on-time of an optical image bar. The image bar output is adapted to be separated into two image outputs which expose two separate areas of a photoreceptor. Each exposed area is developed by a toner of a desired color and the developed image, having two colors thereon, is transferred to a copy sheet to form a two-color output copy.
    Type: Grant
    Filed: August 1, 1990
    Date of Patent: May 12, 1992
    Assignee: Xerox Corporation
    Inventors: Robert P. Loce, James J. Appel
  • Patent number: 5089908
    Abstract: A multiple diode laser array used in a ROS scanning system is modified to reduce the effects of undesirable spatial exposure variation at the surface of certain type of layered, semi-transparent photoreceptors. The spatial absorption variation is later manifested as a "plywooding" pattern formed on output prints derived from the exposed photoreceptor. The laser array is modified to form a merged scanning beam at the photoreceptor surface of two or more diode outputs, each output operating at a different wavelength than the other. In one embodiment, a plurality of diodes, each at a different wavelength, are sequentially addressed, and an image of each diode is scanned across the photoreceptor which results in an exposure distribution that would be similar to that formed by an incoherent beam.
    Type: Grant
    Filed: July 26, 1991
    Date of Patent: February 18, 1992
    Assignee: Xerox Corporation
    Inventors: Ronald E. Jodoin, Robert P. Loce, William L. Lama, James D. Rees, Abd-El-Fattah A. Ibrahim, James J. Appel
  • Patent number: 5081497
    Abstract: A document registration guide as provided by mounting a retractable pattern bearing substrate beneath a glass document platen. The substrate operates in the manner of a window shade, presenting a plurality of document outlines which are visible to an operator during a pre-copy state. The operator can select the appropriate document outline pattern, and position the document to be exposed along the outline ensuring the required and proper registration for that document. At start of scan, the substrate is retracted out of the document exposure area and is returned to its initial position at the end of the copying cycle.
    Type: Grant
    Filed: February 13, 1991
    Date of Patent: January 14, 1992
    Assignee: Xerox Corporation
    Inventors: Vinod K. Agarwal, John A. Durbin, James J. Appel