Patent ID: 6496251
Filing Date: 2002-12-17
Classification: G06K

Abstract:
An apparatus for detecting properties of sheet material by reflected light comprising:an illuminating device arranged to illuminate a line defined along a line plane parallel to the sheet material; a detecting device arranged to detect light reflected along said line; a primary imaging device positioned near an immediate vicinity of said line and having a focal length wherein said illuminating device is positioned generally along a focal plane thereof; and a secondary imaging device positioned along the focal plane of said primary imaging device and disposed between said sheet material and said detecting device; wherein said primary imaging device converts divergently emitted light from said illuminating device into a substantially parallel light pencil to illuminate said line in a first illumination plane at a predetermined angle of incidence, said first illumination plane intersecting said line plane along said line and defining a first illumination angle therewith; wherein said primary imaging device imaging light reflected along said line in a first detection plane at a predetermined angle of reflection onto the secondary imaging device, said secondary imaging device having an aperture arranged to substantially receive those light pencils reflected along said line at said angle of reflection, said first detection plane intersecting said line plane along said line and defining a first detection angle with said line plane; wherein the angle of incidence is equal to the angle of reflection, and the first illumination angle is equal to the first detection angle.