| 摘要 |
The invention relates to the field of printed security documents and, more particularly, to security documents and methods of making security documents bearing enhanced security features. The security documents may include identification documents or any other known documents of value. The security document includes a transparent window area with an ultraviolet blocking agent incorporated therein. Invisible ultraviolet fluorescent ink patterns are printed on respective opposite sides of the ultraviolet blocking agent within the region of the transparent window area. When either the face side or back side of the security document is illuminated with ultraviolet light, only the pattern printed proximate that side within the area of the transparent window becomes visible. When both face and back sides are simultaneously illuminated with ultraviolet light, the patterns printed on both sides of the ultraviolet blocking agent within the area of the transparent window become visible at the same time.
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