| abstract |
A security element comprising a first and a second pattern PAT 1 and PAT 2 formed in or on a substrate, the first pattern PAT 1 being formed by a first material INK1 applied to a first region of the substrate, the second pattern PAT 2 being formed by a second material INK 2 applied to a second region of the substrate, said first and second regions of the substrate overlapping, n whereinn a part of the first pattern PAT 1 overlaps with a part of said second pattern PAT 2, the first material INK 1 comprises a first luminescent dye or pigment DYE 1, which upon excitation by electromagnetic radiation falling within an excitation wavelength range λ 1 a of the first luminescent dye or pigment DYE 1 is capable of emitting electromagnetic radiation in at least one first emission wavelength range λ 1 e, and the second material INK 2 comprises a second luminescent dye or pigment DYE 2, which upon excitation by electromagnetic radiation falling within an excitation wavelength range λ 2 a of the second luminescent dye or pigment DYE 2 is capable of emitting electromagnetic radiation in at least one second emission wavelength range λ 2 e, and said first emission wavelength range λ 1 e of the first luminescent dye or pigment DYE 1 overlaps with the excitation wavelength range λ 2 a of the second luminescent dye or pigment DYE 2, so that upon irradiation with electromagnetic radiation within the excitation wavelength range λ 1 a of the first luminescent dye or pigment DYE 1 the second luminescent dye or pigment DYE 2 is excited, in the area of overlap of the patterns, to emit electromagnetic radiation in the emission wavelength range λ 2 e. |