Patents by Inventor Dirk A. Zwemer

Dirk A. Zwemer 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).

  • Publication number: 20060077400
    Abstract: Measurement of sample surface flatness of a continuously moving sample. A conveyor continuously conveys a sample beneath a grating disposed at a non-zero angle with respect to the plane of conveyance. The relative distance between the sample and the angled grating changes with the horizontal translation of the sample. A camera disposed above the sample and the grating captures, at constant time intervals, a sequence of images, each image comprising a shadow moiré fringe pattern that is indicative of the sample's surface flatness. The continuous change in relative distance between the sample and the grating introduces a known or unknown phase step between the shadow moiré fringe patterns of each successive image. A computer associated with the camera processes the images to determine phase values of pixels at, and the relative height of the sample surface at, selected pixel locations of the sample.
    Type: Application
    Filed: September 30, 2005
    Publication date: April 13, 2006
    Applicant: AkroMetrix, LLC
    Inventors: Dirk Zwemer, Jiahui Pan, Gregory Petriccione, Sean McCarron
  • Patent number: 5835223
    Abstract: A system for measuring surface characteristics of an electronic interconnection component, such as a printed circuit board, by analyzing shadow moire patterns. Printed circuit boards are carried on a continuous conveyor under a grating. For each printed circuit board, a shadow moire fringe pattern is created in response to a determination that the printed circuit board is properly located under a grating and within the field of view of a camera. Fringes of the shadow moire fringe pattern are quantified over one or a multiple of analysis paths to determining if the printed circuit board is unacceptably warped, in which case a signal is generated. For each printed circuit board, multiple images can be captured and mathematically combined, by image subtraction, to produce an enhanced shadow moire fringe pattern that is analyzed for warpage.
    Type: Grant
    Filed: December 30, 1996
    Date of Patent: November 10, 1998
    Assignee: Electronic Packaging Services, Ltd.
    Inventors: Dirk A. Zwemer, Patrick B. Hassell
  • Patent number: 4620916
    Abstract: Degradation retardants reduce electrochemical degradations and provide significantly increased operation lifetimes for the colloidal suspensions of electrophoretic display devices. Suitable degradation retardants include redox agents capable of being repeatedly, reversibly oxidized and reduced in the colloidal suspensions.
    Type: Grant
    Filed: September 19, 1985
    Date of Patent: November 4, 1986
    Inventors: Dirk A. Zwemer, Solomon I. Beilin, Long K. Truong, Lewis T. Lipton