Optical density scanning head

Abstract

Abstract The present device has a housing means which has a central aperture into which there is located a source of white light and a lens arrangement to direct the white light to a focal point which lies just beyond the base of the housing. The housing means has four other apertures formed therein which lie at approximately 45° to the base of the housing and which open into the central aperture so that light reflected from said focal point will be directed through each of said four other apertures. In the preferred embodiment three of said other apertures lie 120° apart and each of these has a different color light filter located therein which receive reflected light from said focal point. In each of said last mentioned apertures the associated color light filter is followed by an infra-red light filter and thereafter by a photosensitive device. Accordingly the present device can direct white light to an area of a sheet of material which is characterized by one or more of the basic colors cyan, magenta and yellow and can produce simultaneously three electrical signals each of which is indicative of the optical density of a different one of the basic colors cyan, magenta and yellow present at said area to which the white light is directed. The fourth aperture normally has a plug therein but when it is removed, the user can make a visual inspection therethrough to see that the white light is properly focused on the area to be monitored.

Inventors

• 👤 Philip E. Tobias

Bibliographic Details