Invention Grant
US07976068B2 Double-blind security features 有权
双盲安全功能

Double-blind security features
Abstract:
A compound security feature is formed by printing latent images together with visually integrated settings using an invisible ink. Even if illuminated by a wavelength capable of rendering the inks visible, the latent images remain visually indistinguishable from their visually integrated settings. However, the latent images and visually integrated settings differ in one or more less obvious ways so that the latent images can be distinguished by using a visual aid.
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