Patents by Inventor Craig T. Johnson

Craig T. Johnson 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: 5907742
    Abstract: A lamp control scheme for rapid warmup of a cold cathode fluorescent lamp, to minimize the warmup time while maintaining long lamp service light. The lamp is over-driven with high current for up to a predetermined time limit to accelerate mercury vaporization. The drive current is then reduced to a normal level. The scanner light output is monitored by a sensor circuit, and the system waits until the light output exceeds a minimum output and the light profile is sufficiently stable. The scanner is then calibrated to a white reference, and the closed loop control of the signal level is activated. The scan or copy process is now performed, and the light level control is deactivated as needed. Thereafter, between uses the lower lamp current is 40% of normal level to keep the lamp warm while extending the life of the product. If the product has not been used in a long time, the lamp is turned off.
    Type: Grant
    Filed: March 9, 1997
    Date of Patent: May 25, 1999
    Assignee: Hewlett-Packard Company
    Inventors: Craig T. Johnson, Gary W. Gragg, Jeffrey A. Sunamoto, Stephen B. Witte
  • Patent number: 5434956
    Abstract: Each two-dimensional alignment mark on a printing medium is found by using information about the whole mark area, or with respect to each of two different directions relative to the medium by using a distinctive two-dimensional pattern or characteristic of the mark; or by finding the mark centroid, or by scanning the mark region to obtain a two-dimensional representation for analysis--and preferably by combinations of these procedures. An image is then aligned and printed by reference to the mark so located. A previous image may also be preprinted in known relation with the mark, so that the new image is aligned with the preprinted one--sometimes on the same piece of medium. Preferably information used includes the mark's intended size, shape, areal disposition and other properties; and a two-dimensional search template is defined which matches the mark in at least one of these.
    Type: Grant
    Filed: November 4, 1992
    Date of Patent: July 18, 1995
    Assignee: Hewlett-Packard Company
    Inventors: Myungsae Son, Craig T. Johnson, Richard M. Dartez