DIFFUSE CAVITY ILLUMINATORS FOR NON-PLATEN OR DVT RIS SYSTEMS
Original Publication Date: 1982-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
An optimum geometry for a diffusely reflective cavity illuminator is a generally rectangular configuration shown in the Figure. As shown, a cavity illuminator 10 shown in cross-section, is positioned beneath a platen 12 upon which a document 14 is to be copied. It is assumed the scanning requirements are such that illumination scan strip 16 is smaller than 0.5 inch. A pair of elongated light sources 18, 19 are placed within the cavity. The interior walls of the cavity are coated with a diffuse paint providing a high reflectance value R in the actinic spectral region. A diffuse white paint is frequently used for this purpose. The cavity has a total perimeter P and has a width W extending into the plane of the Figure. Illumination from within the cavity illuminates point Q in the center of the illumination slit through an aperture 20 having a width L The document reflects a bundle of rays, represented by a principal ray ?; which exit the illuminator through a second aperture 22 of width L1 and are projected via a lens 24 onto an imaging plane (not shown).