METHOD AND APPARATUS FOR CHECKING SECURITY DOCUMENTS

METHODE ET APPAREIL POUR VERIFIER LES DOCUMENTS DE SECURITE

English Abstract

The invention concerns a method and devices for checking security documents.
According to this process which uses known capacitive coupling, electrical
signals are transmitted by transmitting antennae via electrically conductive
security features to receiving antennae and amplified. The amplitude responses
and time characteristics of the electrical signals are then evaluated and
compared with existing signal responses, by being converted into signal
responses having easily comparable parameters. In order to enable the testing
arrangement to be specifically selective, a selective amplifier is
additionally coupled to the evaluation electronics. Currency-specific
definition by means of the evaluation electronics according to the invention
is attained in that, for a given currency, a time limit of the test signal
amplitude can be determined by means of controllers, for example, this time
limit differing from the duration of the amplitude response of all the other
currencies.

French Abstract

L'invention concerne un procédé et des dispositifs permettant de vérifier des documents de sécurité. Selon le procédé de vérification de documents de sécurité, qui fait appel au couplage capacitif connu en soi, il est prévu que des signaux électriques émanant d'antennes émettrices soient transmis à des antennes réceptrices par le biais de caractéristiques de sécurité électroconductrices, et amplifiés. Ces signaux sont ensuite évalués d'après leur réponse d'amplitude et leur réponse en temps, et comparés à des courbes de signaux existantes, par conversion en courbes de signaux présentant des paramètres facilement comparables. Afin de parvenir à une sélectivité spécifique du dispositif de vérification, un amplificateur sélectif est en outre couplé à l'unité électronique d'évaluation. On parvient à une définition propre à la monnaie à l'aide de l'unité électronique d'évaluation, du fait qu'une limite de temps de l'amplitude du signal de vérification différant de la durée de la réponse d'amplitude de toutes les autres monnaies, peut être déterminée par exemple à l'aide de contrôleurs.

Claims

Claims
1. Method of examining security documents by utilizing capacitive
coupling between transmitter and receiver and transmission of energy
between transmitter and receiver by bridging an electromagnetic field by
electrically conductive security strips, tapes, threads or two-dimensionally
structured security materials as well as following evaluation electronics,
characterized by the fact that several antennae arranged in one or more
planes and functioning as transmission and receiving sensors form test fields
in the range of conventional optical sensors present in processing machines
and spatially corresponding with a capacitive test sensor circuit in a
processing machine and activating the test sensor circuit, and that in
connecting the antennae electromagnetic energy is transmitted over the test
object in dependence of its geometry and/or its conductivity, and that several
antennae are energized at least in different phase positions and feed the
transmitted energy to a succeeding selective amplifier (14), that for preventinginterfering energies as well as for suppressing basic conductivities of test
objects, e.g. bank notes, a phase comparator at the output of the selective
amplifier as well as special filters for suppressing interfering and extraneous
energies and an evaluation unit are arranged such that it is possible to
classify electrically conductive security strips, tapes, threads or
two-dimensionally structured security materials, whereby the test object is
force-guidedly moved through the test field in an undefined lateral disposition
during a checking operation.
2. Method according to claim 1, characterized by the fact that the
electronic evaluation circuitry substantially consisting of an analog to digitalconverter and controller or integrator (15), trigger (16), controller, mono-flop(17) and/or AND gate (18) defines amplitude limit excesses (A) and/or the
currency-specific time tk on the basis of the signal characteristic at the output

of the selective amplifier (14).
3. Method according to claim 1 or 2, characterized by the fact that an
authenticity classification is performed by an electronic evaluation circuitry by
setting an amplitude limit (A) for the authenticity of currencies to be checked.
4. Method according to claim 1 or 2, characterized by the fact that the
classification of different bank notes and/or security documents is performed
by an electronic evaluation circuitry by setting, preferably by a controller, a
currency-specific time (tk) and that the test objects having a time t1..tk-1..tnare sorted out.
5. Method according to claim 4, characterized by the fact that with
currencies having identical times (tk) an additional examination is performed
following the authenticity
6. Method according to claim 1 or 2, characterized by the fact that the
evaluation electronics, preferably one or more controllers, by time comparison
and/or voltage comparison delivers a machine-specific signal for deposition
individually classifies objects in special slots or stacking containers.
7. Method according to claim 1 or 2, characterized by the fact that in a
direction intersecting the direction of movement of the test objects the
antennae and/or electrodes are of such two-dimensional longitudinal extent
that even at a defined lateral play of the test objects and regardless of
whether a test object passes through the test apparatus with its front or rear
surface facing upwardly, the security strip or thread will in any case sweep
over the antennae and/or electrodes contacting them at a defined spacing.
8. Method according to claim 1 or 2, characterized by the fact that an
additional examination is performed the result of which is combined by an
\
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AND gate with the signal of the evaluation electronics without necessitating
changing the software of the given processing machine.
9. Apparatus for examining security documents having elements for
capacitive coupling, transmission of energy between transmitter and receiver
by bridging an electromagnetic field by electrically conductive security strips,tapes, threads or two-dimensionally structured security materials and
evaluation electronics, for practicing the method according to claim 1,
characterized by
- conventional optical sensors present in a processing machine for
activating a capacitive test sensor arrangement;
- test fields formed by several sensors arranged in one or more planes
and functioning as transmitting and receiving antennae;
- a selective amplifier (14) and
- a phase camparator connected to the output thereof;
- special filters for suppressing interfering and extraneous energies; as
well as
- an electronic evaluation circuit essentially comprising an analog to
digital converter and a controller or integrator (15), trigger (16), controller,mono-flop (17) and, if desired, an AND-gate, and that during the checking
operation the test object is arranged for moving by the sensors in defined
contact therewith at an undefined lateral disposition by means of hold-down
devices and/or feed belts (10), rollers arranged in this area.
10. Apparatus according to claim 9, characterized by the fact that the
sensors functioning as transmitting or receiving antennae are structured as
strip sensors (8;9) in one plane or in two planes positioned opposite each
other and/or mirror-symmetrically.
11. Apparatus according to claim 9 or 10, characterized by the fact that
the strip sensors (8;9) are provided with recesses and/or apertures and/or
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windows (7) or that such are arranged in the immediate vicinity of the strip
sensors (8;9).
12. Apparatus according to one or more of preceding claims 9 to 11,
characterized by the fact that sensors in test units are arranged mirror-symmetrically
relative to the test zones and/or security strips, threads and/or
tapes of objects to be checked, preferably bank notes, security documents
and packing materials.
13. Apparatus for examining security documents having elements for
capacitive coupling, transmission of energy between transmitter and receiver
by bridging an electromagnetic field by electrically conductive security strips, tapes, threads or two-dimensionally structured security materials and
evaluation electronics, for practicing the method according to claim 1,
characterized by the fact that a plurality of transmitting antennae (A2, A3,
B2.1..B2.n) and a plurality of receiving antennae (A1, B1.1..B1.n) forming a
test sensor arrangement (54) are arranged such that security strips which are
uninterruptedly electrically conductive as well as those provided with a
plurality of electrically conductive sections insulated from each other in a
security strip may be checked, whereby the test sensor arrangement (54) is
arranged displaced tangentially parallel to an arcuate conductor (56) or
tangentially parallel relative to a feed roller (55) and that there are arranged,
orthogonally relative to the direction of the longest dimension of a security
strip and orthogonally to the direction of movement of a document to be
checked, two transmitting antennae (A2, A3) energized at opposite phases
with low or high frequency energy, and one or more oppositely placed
receiving antennae (A1) and, between them, several transmitting antennae
(B2.1..B2.n) disposed parallel relative to the transmitting antennae (A2, A3)
and several receiving antennae (B1.1..B1.n) parallel relative to the
transmitting antennae (B2.1..B2.n), whereby adjacent transmitting antennae
B2.1..B2.1+1) and associated receiving antennae (B1.1, B1.1+1) are displaced
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by a defined distance, preferably the distance between a transmitting antenna
(B2.l) and associated receiving antennae (B1.l) and that the shortest distance
of a transmitting antenna (B2.l) from its associated Receiving antenna (B1.l)
is less than the shortest distance between one of the transmitting antennae
(A2, A3) and the receiving antennae (A1).
14. Apparatus according to claim 13, characterized by the fact that
several transmitting antennae (A2, A3, B2.1..B2.n) and several Receiving
antennae (A1, B1.1..B1.n) are arranged over the entire width of the document
feed path.
15. Apparatus according to claim 13 or 14, characterized by the fact that
the transmitting antennae (A2, A3, B2.1..B2.n) and the receiving antennae
(A1, B1.1..B1.n) are arranged in a plane adjacent to each other, in parallel
and displaced such that an authenticity check of the documents is performed
independently of sides and independently of edges relative to two parallel
document edges.
16. Apparatus according to claim 13, characterized by the fact that
receiving antennae (B1.1..B1.n) and transmitting antenna (B2.1..B2.n)
displaced parallel and/or in a line transversely of the direction of are arranged
in spaced apart relationship such that each security element to be checked
sweeps over a receiving antenna (B1.1..B1.n) and an associated transmitting
antenna (B2.1..B2.n) regardless of its disposition within the document.
17. Apparatus according to claim 13, characterized by the fact that the
longest side of a transmitting antenna (B2.l) and the longest side of the
associated receiving antenna (B1.l) corresponds to the width of the
conductive marking of the security strip.
18. Apparatus according to claim 13, characterized by the fact that
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following rectifiers (45, 48..50) and selective amplifiers (46, 51..53) there are
arranged manipulatable or software-controlled switching and setting
elements, in particular micro-controllers (47) such that the output signals of
the selective amplifiers (46, 51..53) may be combined or logically connected.
19. Apparatus according to claim 13, characterized by the fact that
following rectifiers (45, 48..50) and selective amplifiers (46, 51..53) there are
arranged manipulatable or software-controlled switching and setting
elements, in particular micro-controller (47) such that a change-over between
different types and kinds of documents and degrees of wear is performed
without a change in the arrangement of the sensors.
20. Apparatus according to claim 13, characterized by the fact that the
shortest distance between two transmitting antennae (B2.1) arranged in a row
is greater than the shortest distance between two electrically conductive and
insulated markings of the security strip and that change-over elements are
arranged such that the antennae (A3) are used either as transmitting or as
receiving antennae, depending upon the feeding of the document to be
checked.
21. Apparatus according to claim 13, characterized by the fact that
software or manually controlled switching elements are arranged such that
one or more transmitting antennae (B2.1) and the corresponding receiving
antennae (B1.1) may be selectively activated or deactivated.

Representative Drawing