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Security system with optical waveguide

Inactive Publication Date: 2012-11-29
ORELL FJUSSLI ZIKHERKHAJTSDRUK AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0004]Hence, it is an object to provide a security document of the type mentioned initially that further improves counterfeiting security.
[0006]Since waveguides are generally difficult to manufacture, this measure increases security. The coupler allows to couple light into the waveguide or to observe light guided within the waveguide.
[0008]The document advantageously comprises a first and a second coupler. The two couplers are arranged and structured such that light coupled into the waveguide by means of the first coupler is at least partially transmitted to and coupled out by the second coupler. This makes it possible to operate and verify the waveguide by means of a light source and an observation means (such as a human eye or a detector) outside the waveguide.
[0009]Advantageously, the substrate is non-transparent (i.e. absorbing for the light guided in said waveguide) and has a window or half-window. At least one coupler is arranged in the window. This allows to easily observe light coupled out of the coupler and / or to easily couple light into the waveguide through the coupler, while most of the coupler can be protected by the substrate.
[0012]The waveguide can be embedded at least partially in the substrate, thereby making an exchange or removal more difficult.
[0013]If the waveguide comprises a first and a second layer, with the first layer having a refractive index higher than the second layer, the first layer can be used to guide the optical waves, while the second layer serves to isolate the guided wave from the surroundings. In particular, the second layer can be arranged between the first layer and the substrate, thereby preventing said wave to be absorbed or scattered by the substrate. Advantageously, the waveguide also comprises a third layer, again with the first layer having a higher refractive index than the third layer. The first layer is arranged between the second and the third layer, thereby isolating the wave guided in the first layer on both sides. This is particularly useful if the waveguide is embedded at least over part of its length in the substrate.

Problems solved by technology

Since waveguides are generally difficult to manufacture, this measure increases security.

Method used

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first embodiment

[0031]A first embodiment of the invention is shown in FIGS. 1 and 2, which shows a security document in the form of a banknote.

[0032]The shown security document comprises a flexible or rigid substrate 1 of paper or plastics, onto which graphical elements, for example in the shape of security designs 2, illustrations 3 and indications of value 4, are printed in known manner. In addition the document possesses a security feature 5, the design of which is described in the following.

[0033]In the embodiment of FIGS. 1 and 2, substrate 1 consist of a laminate of a first paper layer 6a, a second paper layer 6b, and a waveguide 7 in the form of a transparent plastics layer between them. The paper layers 6a, 6b are non-transparent. Two windows 8a, 8b are provided in substrate 1. They are formed by holes in the two paper layers 6a, 6b. Waveguide 7 extends through both of them.

[0034]At the location of the windows 8a, 8b, waveguide 7 is provided with a first and a second coupler 10a, 10b, respe...

second embodiment

[0040]FIG. 3 shows a second embodiment of a waveguide-based security device. It illustrates different types of couplers that can be used, as well as a different type of substrate.

[0041]First, in FIG. 3, substrate 1 is substantially solely formed by waveguide 7, and the paper sheets 6a, 6b have been replaced by ink layers 12a, 12b, which have e.g. been applied to both sides of waveguide 7 by means of printing techniques, such as offset print. Again, two windows 8a, 8b are formed on the document by omitting any print in the corresponding regions or by applying only ink or varnish of reduced absorbance.

[0042]In the region of first window 8a, the first coupler is formed by scattering objects embedded in (or arranged on) waveguide 7. The scattering objects can e.g. be formed by embedding scattering particles in waveguide 7, or by locally modifying waveguide 7, e.g. by means of laser irradiation.

[0043]In the region of second window 8b, second coupler 10b is also embedded within waveguide ...

third embodiment

[0049]Yet another embodiment is shown in FIG. 4. Here, one of the couplers, e.g. second coupler 10b, has been replaced by at least one perforation, advantageously a plurality of perforations, 14. Each perforation extends through waveguide 7 and creates an edge therein that gives rise to a scattering of the light within waveguide 7. Hence, when light is propagating along waveguide 7, part of it is scattered at the perforations 14, and the perforations 14 will start to emit light. The perforations 14 advantageously extend all the way through non-transparent substrate 1, thus that light can be emitted to both sides of the document.

[0050]The perforations can e.g. be manufactured by means of laser drilling, such as described in WO 2004 / 011274.

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Abstract

A security document comprises a substrate (1) and an optical waveguide (7). Couplers (10a, 10b) are provided in the waveguide (7) for coupling light into and out of the waveguide. The couplers (10a, 10b) can e.g. by gratings, scattering objects, holograms, luminescent dyes or perforations. The authenticity of the document can be verified using methods based on the properties of the waveguide.

Description

TECHNICAL FIELD[0001]The invention relates to the field of security documents, such as banknotes, passports or credit cards.BACKGROUND ART[0002]Security documents have a substrate, which may be flexible, and on or in which there is arranged at least one security feature for the verification of the authenticity of the security document.[0003]Volume or surface holograms or refractive gratings have, inter alia, been suggested as security features, in particular for bank notes, credit cards or passports. Even though such features are hard to counterfeit, they can be imitated if sufficient efforts are undertaken by a counterfeiter.DISCLOSURE OF THE INVENTION[0004]Hence, it is an object to provide a security document of the type mentioned initially that further improves counterfeiting security.[0005]This object is achieved by a security document comprising a substrate and an optical waveguide arranged on and / or in said substrate. The waveguide comprises at least a coupler structured and a...

Claims

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Application Information

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IPC IPC(8): B42D15/00
CPCB42D2033/20B42D2035/20G02B6/34G07D7/12B42D25/346B42D25/355B42D25/00B42D25/328B42D25/29B42D25/324B42D25/351B42D25/36B42D25/21B42D25/40G02B6/26
Inventor EICHENBERGER, MARTIN
Owner ORELL FJUSSLI ZIKHERKHAJTSDRUK AG