| 摘要 |
<p>A counterfeit resistant document having a set of indicia on a background field. The set of indicia and the backgroud field are characterized by different optical reflectivities for incident light having wavelengths within the response spectrum of the human eye, and are substantially nonabsorbing with respect to incident light having wavelengths within the response spectrum of color xerographic copying machines. The document includes two types of ink particles deposited on a substrate, with the types of ink particles having different, non-uniform spatial distributions over the background field, and at least a first type being substantially non-absorbing with respect to light in the response spectrum of a color copier. The distributions define the indicia set by providing that substantially no ink particles of the first type overlie the substrate within the contours of the indicia, and particles of that type immediately surround those contours, so that a uniform optical reflectivity is present over the indicia and immediately surrounding the background field for incident light having wavelengths within the copier spectrum.</p> |
