FR2812434A1 - METHOD FOR SECURING SENSITIVE ARTICLES AND RELATED ARTICLES - Google Patents

Abstract

A marker which may consist of very fine metallic fibres with microactuators as junctions is installed using the printing ink or a special security wire into a banknote or other document to be protected. The junctions may be opened or closed by magnetic or electric action to give a fibre configuration which will produce a known response to a given excitation.

Description

The present invention relates to a method for securing articles

  sensitive, and a sensitive article subject to such a process.

  The invention finds an advantageous application in the production of banknotes or fiduciary documents, but can also be applied to the manufacture of product authentication labels.

  sensitive or to the security of any sensitive product.

  Many techniques are known for associating with an object a marking which is imperceptible to an observer, but which can be recognized by

  a machine for authentication purposes.

  It is thus known to integrate into banknotes markings invisible to the naked eye, but having specific optical, electromagnetic or electrical properties, only machines

  adapted to determine the presence of these properties.

  More specifically, there are methods for integrating into banknote paper fibers, for example metallic fibers, having specific electrical or electromagnetic properties, recognizable at a distance by machines capable of emitting an excitation signal of the fibers and to collect and recognize a specific signature

of said fibers.

  An example of such a method can be found in US Pat. No. 4,265,703. The fibers can thus be detectable by microwave reading (of the microwave type in particular) or by magnetic field measurement (the

  fibers then providing a specific magnetic signature).

  Such provisions constitute security elements of the tickets, but do not absolutely guarantee the absence of counterfeiting because it is always possible that counterfeiters are aware of the characteristics of the expected response of the tickets to an authentication excitation, and elaborate marking means

reproducing these characteristics.

  In addition, it would be advantageous, in certain circumstances, to distinguish more particularly a given batch of tickets or sensitive products by a specific marking, in order to follow the progress of

  these notes or objects once put into circulation.

  This could be used to establish traceability of the progress of the specific batch, for statistical purposes for example. One could thus imagine associating with a particular batch of products such as perfume bottles such a specific marking, to visualize the geographic distribution of the bottles of this batch. This could also be implemented

  work for the marking of batches of particular banknotes.

  An object of the invention is to allow marking of sensitive objects such as banknotes, with a level of

  increased security compared to the known arrangements mentioned above.

  Another object of the invention is to make it possible moreover to establish a

  traceability on particular batches of such sensitive objects.

  In order to achieve these goals, the invention relates according to a first aspect to a method of securing an article such as a fiduciary document, comprising: * the integration into said article of at least one marker having a characteristic response to an excitation given, said given excitation and said characteristic response possibly being of an electrical and / or magnetic nature, said response being imperceptible to an observer, the exposure of the article to said given excitation, When collecting said response, * and verifying the authenticity of the article by comparison of the response with a reference response, characterized in that the method also comprises the modification of a property of at least one marker so as to modify said characteristic response. Preferred but nonlimiting aspects of the method according to the invention are as follows: said property modification is carried out without contact with the article, said property modification is carried out by exposure to an electric or magnetic field, said marker including a property is modified is produced in the form of sections of metallic fibers connected by connections that can be opened by exposure to an electric or magnetic field, To said modified property is linked to a microwave reflection coefficient, To said connections are produced by microactuators, * said connections are made by structures deformable by magnetostriction, said property modification is reversible, To said article is produced on a paper support, * said marker having a characteristic response to a given excitation is integrated into said article in the form of fibers, boards or metallic particles, ò said marker having a characteristic response to a given excitation is integrated into a printing ink of said article, To said marker having a characteristic response to a

  given excitation is integrated into a safety wire, said wire being itself

even integrated into said article,

  Upon said modification of ownership is controllable.

  According to a second aspect, the invention also relates to a fiduciary document produced on a paper or polymer support incorporating at least one marker whose electrical or electromagnetic property is modifiable so as to modify the response of said marker to a field.

  electric or electromagnetic excitation.

  Preferred but non-limiting aspects of the fiduciary document according to the invention are as follows: On said modification of property is carried out by exposure to a

electric or magnetic field.

  To said marker, a property of which is modified, is produced in the form of sections of metallic fibers connected by links which can be opened by exposure to an electric or magnetic field. To said modified property is linked to a microwave reflection coefficient.

  * said connections are made by microactuators.

  * said connections are made by deformable structures

by magnetostriction.

  Said marker presenting a characteristic response to a given excitation is integrated into said document in the form of

  fibers, boards or metallic particles.

  * the marker having a characteristic response to a given excitation is integrated into a printing ink of said document. * said marker having a characteristic response to a

  given excitation is integrated into a safety wire, said wire being itself

even integrated into this document.

  Other aspects, aims and advantages of the invention will appear better

  on reading the following description of preferred embodiments of

  the invention, which is made with reference to the marking of banknotes, but it will be understood that the invention can be implemented with any type

sensitive article.

  It has been said that it was known to associate banknotes with means of marking imperceptible to an observer such as metallic fibers, the presence of which in the note can only be recognized by a suitable machine. Such fibers thus constitute security markers of the ticket. And it is possible to associate other types of markers, with a specific physical, chemical, or even biological property, with a ticket. We will now describe a ticket comprising a security marker whose, according to the invention, the characteristic response to an excitation emission can be modified if desired. Thus, according to an essential aspect of the invention, it is possible to specifically process a particular ticket or batch of tickets to modify the

  response of the batch tickets to the excitation of the authentication machine.

  According to a first embodiment, the fibrous frame of the banknotes can comprise metallic fibers including an authentication machine

  is able to determine the electrical conductivity.

  To be integrable in the ticket paper and aesthetically acceptable, these fibers must have a suitable diameter (60 μm maximum for a paper whose grammage is of the order of 100 g / m2), with a

  length up to a few centimeters.

  When a ticket containing such fibers is exposed to microwave radiation, part of this radiation is absorbed

  by the fibers while the unabsorbed part is reflected.

  And the ratio between the reflected part and the absorbed part depends on the characteristics of the fibers, inter alia their diameter or a characteristic dimension, their length, and the implantation of the fibers.

  in the ticket (concentration and dispersion of fibers).

  Thus, it is possible to design an authentication machine provided with means for emitting microwave radiation, and with means for receiving and measuring the part of the radiation reflected. Such a machine makes it possible to characterize the presence of the fibers in the banknotes, and

  the characteristics of the fibers set out above.

  The ratio between the reflected and absorbed microwave energy can thus be defined as representative of a microwave conductivity of the fibers. And this conductivity is directly linked to the characteristics of the

  fibers, and in particular their length.

  To distinguish the banknotes from the selected batch, the conductivity of the fibers present in these particular banknotes is modified according to the invention by implementing a technique for modifying conductivity which can be actuated at

  distance as described below.

  To implement such a modification of the conductivity of the fibers and according to a first embodiment, at least some of said fibers have been made up of two or more sections of fiber, the

  sections being linked two by two by microactuators.

  A microactuator is a nanostructure formed by vacuum deposition (or possibly by another technique, for example electrolytic deposition) of layers of particles on a substrate (of silicon by

example).

  And it is possible to modify the state of such a microactuator by exposure to an electric field. Depending on the characteristics of the microactuator, the threshold value of the electric field beyond which

  the structure of the microactuator is modified can be very weak.

  However, in the context of the invention, microactuators will be used, the structure of which can only be modified by exposure to a field greater than a threshold of the order of a few tens of Volts, of

  preferably around 150 Volt.

  More specifically, the microactuators are deposited using

  masks so as to connect two sections of fibers.

  The fiber sections were made up by cutting by chemical attack of a fiber, which was itself produced by deposits

  of electrically conductive metal on a substrate such as silicon.

  Such deposits can have a total thickness of the order of a few microns to a few tens of microns. The chemical attack can be carried out by deposition of acid or sodium hydroxide, depending on the constituent metal

fiber.

  One thus constitutes tickets comprising an imperceptible marking in the form of metallic fibers, the characteristics of said imperceptible marking being able to be altered following the exposure of the ticket to a field.

  electric above the threshold mentioned above.

  Indeed, if these tickets are exposed to an electric field whose value is greater than this threshold, the microactuators are activated so that the fiber sections are separated from each other, and the conductivity of the ticket

is modified.

  Thus, the microactuators play the role of switches actuable by exposure to an electric field, to modify the response of the ticket to

  the exposure of the authentication machine radiation.

  And given the large value of the electric field threshold for actuating microactuators, an untimely modification of the structure of the fibers, and therefore of the characteristics of the ticket response, is avoided. According to an alternative embodiment, the microactuators can be replaced by geometrically deforming structures under exposure to a magnetic field, under the effect of a magnetostriction phenomenon. In this case, the deformation of these structures is adapted to separate the fiber sections, so that the conductivity of the ticket is also altered as a result of the opening of the "switch" that

constitutes the deformable element.

  The markers can also be manufactured using a sheet of ferroelectric material deposited on a flexible polymer support cut into fibers, wires or any other type of small particle (up to a few tens of microns thick and a few

mm2 on the surface).

  These particles can then be incorporated directly into the paper weft of the banknotes, or into a ticket printing ink, or else deposited directly on the banknote (in this case they can be

coated with varnish).

  They can also be manufactured from a polymer wire support of a few microns in diameter on which these ferroelectric materials have been deposited followed by their protective layers. The wire is then itself deposited on the paper, or integrated into the weft of the ticket paper. In this way, we combine the characteristics of the materials

  ferroelectric with those of fibers.

  It has been said that a preferred application of the invention relates to the security of banknotes; however, as has been said, it is also possible to apply the invention to other types of sensitive articles. In particular, according to the invention, it will be possible to produce security articles or documents produced not on a paper support, but on a polymer support (ticket with a fibrous frame comprising polymers, or supports of the credit card type, insertion into a glue

associated with the support).

  It is therefore possible according to the invention to specifically treat a batch of sensitive products such as tickets, provided with an imperceptible marking, to modify the characteristics of this marking in order to

distinguish the lot in question.

  Of course, the invention is not limited to the embodiments

described above.

  In particular, it is possible to implement the invention so as to control the characteristics of the response of the tickets when the

fibers have been disjoined.

  In this way, authentication by a machine can result in A valid ticket value, but not modified, if the response of the ticket conforms to a valid ticket reference response, stored in a memory of the authentication machine , To a valid modified ticket value (valid ticket which has been processed to mark it specifically), said modified valid ticket value also being predefined in a memory of the authentication machine, and constituting a second reference value different from the first one,

  At or an invalid ticket value.

  And response modification processing may be irreversible, or

well reversible.

  In addition, this treatment can be carried out remotely as in the embodiments described above (exposure to an electric or magnetic field), but also can be carried out by contact with tickets or

products to be modified.

  Finally, if a preferred application of the invention consists in modifying an electrical type response (the metallic fibers producing an antenna effect to absorb certain microwaves and to reflect others), the response whose characteristics are to be altered may also be magnetic (and the alteration of the response may in this case consist of the application of an excitation magnetic field so as to cause magnetic resonance and modify the magnetic characteristics

  markers, which can be fibers with soft magnetism).

  And it is of course possible to superimpose, in association with the same sensitive object, electrical markers and magnetic markers, the authentication machines being able in this case to include means for exciting the markers of the object and receiving their response solely electric, or only magnetic, or else

  electric and magnetic at the same time.

  And in the latter case, it is possible to modify only one type of response (electrical or magnetic) to distinguish the product that is

  wishes to follow more particularly.

Claims (22)

  1. A method of securing an article such as a fiduciary document, comprising: integrating into said article at least one marker having a characteristic response to a given excitation, said given excitation and said characteristic response possibly being of an electrical nature and / or magnetic, said response being imperceptible to an observer, On exposure of the article to said given excitation, * collecting said response, À and verifying the authenticity of the article by comparing the response to a reference response, characterized in that the method also includes modifying a property of at least one marker so as to modify said characteristic response.   2. Method according to claim 1, characterized in that said   modification of property is carried out without contact with the article.   3. Method according to claim 2, characterized in that said modification of property is carried out by exposure to a field electric or magnetic.   4. Method according to claim 3, characterized in that said marker, a property of which is modified, is produced in the form of sections of metal fibers connected by links which can be opened by   exposure to an electric or magnetic field.   5. Method according to claim 3 or 4, characterized in that said   modified property is related to a microwave reflection coefficient.   6. Method according to claims 4 and 5 taken as a whole,   characterized in that said connections are made by microactuators. 7. Method according to claim 4, characterized in that said connections   are made by structures deformable by magnetostriction.   8. Method according to one of the preceding claims, characterized in that   that said modification of property is reversible.   9. Method according to one of the preceding claims, characterized in that   that said article is produced on a paper support.   10. Method according to claim 9, characterized in that said marker having a characteristic response to a given excitation is integrated into said article in the form of fibers, boards or metallic particles.   11. Method according to one of the preceding claims, characterized in that   that said marker exhibiting a characteristic response to a   given excitation is incorporated into a printing ink of said article.   12. Method according to one of the preceding claims, characterized in that   that said marker having a characteristic response to a given excitation is integrated into a safety thread, said thread being itself integrated into this article.   13. Method according to one of the preceding claims, characterized in that   that said modification of property is controllable.   14. Fiduciary document produced on a paper or polymer support incorporating at least one marker, an electrical or electromagnetic property of which can be modified so as to modify the response of said   marker to an electric or electromagnetic excitation field.   15. Fiduciary document according to claim 14, characterized in that said modification of property is carried out by exposure to a field electric or magnetic.   16. Fiduciary document according to claim 15, characterized in that said marker, a property of which is modified, is produced in the form of sections of metal fibers connected by links which can be   opened by exposure to an electric or magnetic field.   17. Fiduciary document according to claim 15 or 16, characterized in that said modified property is linked to a reflection coefficient of microwaves.   18. Fiduciary document according to claims 16 and 17 taken in their   together, characterized in that said connections are made by microactuators. 19. Fiduciary document according to claim 16, characterized in that said connections are made by structures deformable by 2 5 magnetostriction.   20. Fiduciary document according to one of claims 14 to 19, characterized   in that said marker having a characteristic response to a given excitation is integrated into said document in the form of fibers,   metal plates or particles.   21. Fiduciary document according to one of claims 14 to 20, characterized   in that the marker exhibiting a characteristic response to a   given excitation is integrated into a printing ink of said document.   22. Fiduciary document according to one of claims 14 to 21, characterized   in that said marker having a characteristic response to a given excitation is integrated into a safety thread, said thread being itself integrated into this document.