Patents by Inventor Frederic R. Engstrom

Frederic R. Engstrom 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: 7350925
    Abstract: Described is an optical lens having a light-receiving surface facing a light source and a first structured surface opposite a first portion of the light-receiving surface. The first structured surface includes a plurality of first reflecting surfaces and first refractive surfaces. Each of the first refractive surfaces receives light from a corresponding first reflective surface for refractive transmission therethrough. The optical system may further include a second structured surface opposite a second portion of the light-receiving surface. The second structured surface includes a plurality of second refractive surfaces. Each of the second refractive surfaces receives light directly from the light-receiving surface.
    Type: Grant
    Filed: September 7, 2004
    Date of Patent: April 1, 2008
    Assignee: 3M Innovative Properties Company
    Inventor: Frederic R. Engstrom
  • Patent number: 7196687
    Abstract: Methods for illuminating the display area of a liquid crystal panel (13) are provided. Illumination light (17) is compressed into a stripe which is scanned across the display area in synchronization with the display's refresh cycle. In particular, the scanning is performed so that for each row of the display, the majority of the illumination light which impinges on the row as a result of the scan is in the last half of the cycle fresh period for the row. In this way, the ability to display moving objects is improved.
    Type: Grant
    Filed: November 3, 2003
    Date of Patent: March 27, 2007
    Assignee: 3M Innovative Properties Company
    Inventors: Arlie R. Conner, Frederic R. Engstrom
  • Patent number: 7029130
    Abstract: The present invention is particularly useful for projection systems in which portions of an unwanted light beam overlap with the image beam. Such an overlap reduces the image contrast. Under the present invention, an aperture is used to restrict the extent of the unwanted beam while an integrator changes the shape of the light beam illuminating the image display device. The integrator changes the illumination beam so as concentrate the light in those areas of the illumination beam that are transmitted through the aperture. When the aperture and the integrator are used together in the projection system, both the image brightness and the image contrast are increased.
    Type: Grant
    Filed: December 30, 2003
    Date of Patent: April 18, 2006
    Assignee: 3M Innovative Properties Company
    Inventors: Bruce L. Cannon, Gary B. Kingsley, Frederic R. Engstrom, Peter R. Oehler
  • Publication number: 20040135754
    Abstract: Methods for illuminating the display area of a liquid crystal panel (13) are provided. Illumination light (17) is compressed into a stripe which is scanned across the display area in synchronization with the display's refresh cycle. In particular, the scanning is performed so that for each row of the display, the majority of the illumination light which impinges on the row as a result of the scan is in the last half of the cycle fresh period for the row. In this way, the ability to display moving objects is improved.
    Type: Application
    Filed: November 3, 2003
    Publication date: July 15, 2004
    Inventors: Arlie R. Conner, Frederic R. Engstrom
  • Patent number: 4223083
    Abstract: An improved method of screening a color cathode ray tube of the shadow mask type is disclosed. The shadow mask is used to form a corresponding virtual mask on the outer or viewing surface of the CRT faceplate. The virtual mask then is employed as a substitute for the shadow mask in the subsequent photoprinting of a color display screen on the faceplates's inner surface. Advantages include reduced handling of the fragile shadow mask, which reduces the costs associated with replacing such masks if they become damaged, and better defined and registered phosphor deposits.
    Type: Grant
    Filed: December 27, 1977
    Date of Patent: September 16, 1980
    Assignee: Tektronix, Inc.
    Inventor: Frederic R. Engstrom