Patents by Inventor Ervin D. Labrum

Ervin D. Labrum 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: 4408873
    Abstract: Subtractive filters are moved into and outfrom the light path between a lamp and a supported color transparency in a color enlarger to provide three separate exposures for the colors red, green and blue. Operator setable means provides an exposure time for each color exposure based on the color density of a standardized transparency. Balance circuit adjusts the exposure time for each color exposure to compensate for differences in color density between the standardized transparency and a transparency from which a color print is to be made. The balance circuit includes a light intensity sensor between the transparency and the lens. Magenta and yellow filters are moved together into the light path to produce the color red. Yellow and cyan filters produce the color green. Cyan and magenta filters produce the color blue. At the end of the red exposure the cyan filter is moved back into the white light path before the yellow filter is withdrawn.
    Type: Grant
    Filed: December 8, 1980
    Date of Patent: October 11, 1983
    Inventor: Ervin D. Labrum