Invisible, machine-detectable security marking, production of the security marking, and security system comprising this security marking
AssigneeSicpa Holding SA
InventorsChristoph Müller-Rees, Jürgen Küpfer, Horst Leigeber, Georg Schwalb
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Abstract
The invention relates to a security marking whose level of proof against forgery is greater than that of known security markings, comprising liquid-crystalline material with chiral phase, wherein the security marking is imperceptible to the eye and the properties of the liquid-crystalline material with chiral phase can be detected with the aid of detection systems.
Claims12
A security marking useful for detecting forgery, said security marking comprising at least two invisible liquid crystalline materials with chiral phase and having no color in the visible region observable by the eye, said invisible liquid crystalline material detectable with the aid of a detection system,
- wherein said two invisible liquid crystalline materials have central wavelengths of their reflection spectrum which differ by more than 1%, or bandwidths of their reflection band which differ by more than 2%, and have opposite handedness.
A security system comprising an article carrying a security marking comprising at least one invisible liquid crystalline material with chiral phase, having no color in the visible region observable by the eye and having a reflection band, and a test setup for recognizing said at least one security marking by identification of a characteristic form of the reflection band of said visible liquid-crystalline material, said characteristic form being measured at at least two spectrally different points on the reflection band of said invisible liquid-crystalline material, wherein at least one spectral point corresponds to the peak of the reflection band at a given condition of light incidence and reflection, and a second spectral point corresponds to a wavelength wherein the intensity of the reflection band has fallen to from 10% to 50% of the intensity of the peak of the reflection band.
Dependencies are inferred from the claim text.