Data carrier with optically variable color

Details Data carrier with optically variable color Data carrier with optically variable color

1998-09-21

2001-02-06

Wellington, A. L. (Department: 3722)

Printed matter

Having revealable concealed information, fraud preventer or...

Having specific color

C283S086000, C283S091000, C283S094000, C283S109000, C427S007000

Reexamination Certificate

active

06183018

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a data carrier, in particular a paper of value, identity card or the like, which is provided with an optically variable security element having optically variable pigments without, or with only weak, body color of their own.
2. Description of the Prior Art
There have been manifold efforts lately to mark data carriers and protect them from falsification or forgery. In particular the improved quality of photocopiers has caused optically variable elements to be increasingly applied to security documents whose optically variable effect is not reproducible by copying machines.
For example it is known from EP 0 317 514 A1 to apply to a document a layer with iridescent substances which conveys a different color effect at different viewing angles. It is in particular proposed that the iridescent substance be applied flat to a subjacent, black, all-over layer. In a further working step the thus produced iridescent surface can be overlaid with information by overprinting this surface.
EP 0 435 029 A3 furthermore discloses the use of liquid-crystal polymers as optically variable elements whereby a color tilting effect arises upon a change of viewing or lighting angle. This effect is based substantially on the helical structure of the liquid-crystal phase, which can be fixed by crosslinking in polymers and furthermore adjusted via external conditions, such as mechanical pretreatment. This also makes it possible to selectively adjust the color tone of the color change.
SUMMARY OF THE INVENTION
The problem to be solved by the invention is to propose a data carrier, and a method for producing it, which has a novel optical effect and thus increased protection from forgery.
The invention is based on the idea of first providing the document with information contrasting with the data carrier, such as a finely structured print. One then provides this information with an optically variable effect by applying a transparent layer having an optically variable effect over at least a partial area of the information. One can use in particular transparent optically variable layers having optically variable pigments without, or with only slight, body color of their own. One can furthermore use other transparent optically variable layers, such as interference layer structures or optically variable foils such as liquid-crystal silicone polymer foils.
The layer having an optically variable effect can be applied according to the invention by coating, transfer printing, another manner of application, applying a foil or imprinting. The invention will be described by way of example using imprinting, but the abovementioned other techniques can also be used analogously for applying the optically variable layer.
When conventional coloring pigments are used to apply structured prints to a data carrier, the inventive method offers the possibility of providing this information with an optically variable effect For this purpose the information is provided flat at least in partial areas with a transparent, optically variable layer having e.g. an optically variable pigment without, or with only slight, body color of its own. The lack of body color in the optically variable pigments makes these pigments especially effective at the places where the first ink is located on the data carrier as a structured background. In contrast, the optically variable effect is not, or only hardly, visible at the places where no background print is present. When the abovementioned optically variable pigments are used in inks, the width or fineness of the producible structures is limited and is considerably greater than the line thicknesses achievable with conventional pigments, since the optically variable pigments are much larger than conventional pigments so that one cannot produce information as a high-resolution structure by directly printing the pigments. Furthermore the size of the optically variable pigments makes them unprintable by screen printing as of a certain mesh width of the screen, so that this technique cannot be used to produce a high-resolution structure anyway. It is therefore to be regarded as a particular advantage of the inventive method that this technique can now be used to provide even high-resolution structures with an optically variable effect when the high-resolution structures are printed with the first ink and then covered with the ink containing the optically variable pigment.
The invention accordingly achieves the advantage of providing the document with a high-resolution fine structure which furthermore has a previously unknown optically variable effect for the viewer. The inventive procedure offers the further advantage that the formation of the fine structure is decoupled from the formation of the optically variable effect, so that the pigments optimized for the case of application can be used for the particular desired effect.


REFERENCES:
patent: 4514085 (1985-04-01), Kaye
patent: 5808758 (1998-09-01), Solmsdorf
patent: 0 642 933 A1 (1995-03-01), None
patent: 2 283 456A (1995-05-01), None

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