PRINTED SECURITY FEATURE, OBJECT COMPRISING SUCH A PRINTED SECURITY FEATURE, AND PROCESS OF PRODUCING THE SAME

摘要

There is described a printed security feature (1) provided onto a printable substrate, which security feature includes a printed area (100) consisting of a multiplicity of adjacent rectilinear and/or curvilinear elements (110, 120) printed with a given spatial frequency. The rectilinear and/or curvilinear elements are printed with at least first and second inks which exhibit the same or substantially the same optical appearance when illuminated with visible white light, such that the security feature produces a first graphical representation when illuminated with visible white light, at least the first ink being an ink which responds to non- visible light excitation by producing a characteristic optical response differentiating the first ink from the second ink. The security feature produces a second graphical representation when illuminated with non-visible light, which second graphical representation exhibits a distinctive two-dimensional graphic element (B) which is revealed only when the security feature is illuminated with non-visible light. Inside boundaries (160) of the distinctive two-dimensional graphic element, a part (P3) of the rectilinear and/or curvilinear elements is printed with a combination of the first and second inks, the rectilinear and/or curvilinear elements being subdivided, within that part, into first and second juxtaposed sections (110a, 110b, 120a, 120b) which are respectively printed with the first ink and with the second ink. Outside the boundaries of the distinctive two-dimensional graphic element, portions (P1, P2) of the rectilinear and/or curvilinear elements are printed with only one of the at least first and second inks. The at least first and second inks are printed in register one with respect to the other so that the boundaries of the distinctive two-dimensional graphic element are not visible when the security feature is illuminated with visible white light and the distinctive two-dimensional graphic element only becomes visible when the security feature is illuminated with non-visible light.