U.S. patent application number 15/312685 was filed with the patent office on 2017-07-20 for anti-counterfeiting label for detecting cork alterations.
This patent application is currently assigned to WISEKEY SEMICONDUCTORS. The applicant listed for this patent is WISEKEY SEMICONDUCTORS. Invention is credited to Ghislain BOIRON, Mikael DUBREUCQ, Jean-Pierre ENGUENT, Pierre PIC.
Application Number | 20170203895 15/312685 |
Document ID | / |
Family ID | 51352670 |
Filed Date | 2017-07-20 |
United States Patent
Application |
20170203895 |
Kind Code |
A1 |
PIC; Pierre ; et
al. |
July 20, 2017 |
ANTI-COUNTERFEITING LABEL FOR DETECTING CORK ALTERATIONS
Abstract
A near field magnetically coupled contactless device includes a
foldable substrate in the form of a tape; two metal surfaces
located facing each other on opposite sides of the substrate in a
region of interest of the substrate, configured such that a
piercing of the region of interest causes a permanent short circuit
between the two metal surfaces; and a circuit configured to detect
a short circuit between the two metal surfaces.
Inventors: |
PIC; Pierre; (Ceyreste,
FR) ; ENGUENT; Jean-Pierre; (Aix en Provence, FR)
; DUBREUCQ; Mikael; (Aix en Provence, FR) ;
BOIRON; Ghislain; (Aix en Provence, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WISEKEY SEMICONDUCTORS |
Meyreuil |
|
FR |
|
|
Assignee: |
WISEKEY SEMICONDUCTORS
Meyreuil
FR
|
Family ID: |
51352670 |
Appl. No.: |
15/312685 |
Filed: |
May 18, 2015 |
PCT Filed: |
May 18, 2015 |
PCT NO: |
PCT/FR2015/051290 |
371 Date: |
November 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65D 55/06 20130101;
G06K 19/0739 20130101; B65D 1/023 20130101; H04B 5/0062 20130101;
H04L 9/32 20130101; B65D 2555/02 20130101; B65D 2203/10 20130101;
G06K 19/07 20130101; B65D 55/028 20130101; B65D 39/0011 20130101;
G06K 19/07798 20130101; B65D 2539/008 20130101; G06K 19/07381
20130101; B65D 39/0058 20130101; G08B 13/2431 20130101 |
International
Class: |
B65D 55/06 20060101
B65D055/06; G06K 19/077 20060101 G06K019/077; H04B 5/00 20060101
H04B005/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 21, 2014 |
FR |
14 54571 |
Jul 2, 2014 |
FR |
14 56328 |
Dec 1, 2014 |
FR |
14 61751 |
Claims
1. A near field magnetically coupled contactless device,
comprising: a foldable substrate in the form of a tape; two metal
surfaces located facing each other on opposite sides of the
substrate in a region of interest of the substrate, configured such
that a piercing of the region of interest causes a permanent short
circuit between the two metal surfaces; and a circuit configured to
detect a short circuit between the two metal surfaces.
2. The device of claim 1, comprising: an antenna circuit tuned to a
nominal frequency, including an antenna and a first capacitor
connected to the antenna; and a sacrificial capacitor formed by the
two metal surfaces connected to the antenna circuit to contribute
to the tuning of the antenna circuit to the nominal frequency.
3. The device of claim 2, wherein the sacrificial capacitor is
connected in series with the antenna.
4. The device of claim 2, wherein the antenna encircles the region
of interest.
5. The device of claim 2, comprising a control microcircuit
connected to be powered by the antenna circuit, and including
information transmission functions and cryptographic functions;
wherein the antenna circuit tuning parameters are selected so that
a short circuit of the sacrificial capacitor lowers the supply
power received by the microcircuit to a level insufficient for
supplying the cryptographic functions, yet sufficient for supplying
the transmission functions.
6. The device of claim 2, comprising a conductive track for
connecting the sacrificial capacitor to the antenna circuit,
configured to cross areas of preferential rupture of the tape.
7. A container comprising: a cork; and a contactless device
according to claim 6 adhesively secured over the container and the
cork so that the region of interest of the substrate is in
correspondence with the cork.
8. The container of claim 7 in the form of a bottle comprising a
cap enveloping the cork, the neck of the bottle, and the tape, the
cap including, in the vicinity of the cork, a material permeable to
magnetic field.
Description
FIELD
[0001] The invention relates to near field magnetically coupled
contactless identification devices, e.g. NFC, ISO 14443, or ISO
15693 devices, and more specifically to an anti-counterfeiting
contactless device for ensuring authenticity of the contents of a
bottle.
BACKGROUND
[0002] U.S. Pat. No. 7,898,422 describes an anti-counterfeiting NFC
device integrated in a wine bottle cork. The device is arranged so
that the insertion of a corkscrew damages the antenna or the
control microcircuit.
[0003] When the device is intact, it can be interrogated remotely
by an NFC reader to retrieve information on the product, and also
to confirm the authenticity of the information. When the cork has
been removed, the NFC device is damaged, so that the cork cannot be
reused to authenticate the content of a new bottle.
[0004] US patent application 2005-0012616 discloses an RFID tag
having a sacrificial antenna designed to be broken at the opening
of a container, for example. The sacrificial antenna enables
reading the tag in an extended distance range. When the sacrificial
antenna is broken, the tag can continue to operate in an
antenna-less mode with a limited reading distance range.
[0005] US patent application 2007-0210173 describes an RFID tag in
two parts, each of which includes an independent RFID component
having cryptographic functions. A tag rupture renders one of the
two RFID components inoperative. A reader is programmed to signal
that the tag is intact if it manages to negotiate authentication
with both RFID components of the tag. The tag is considered as
damaged if only one authentication can be negotiated.
SUMMARY
[0006] In general, a near field magnetically coupled
anti-counterfeiting tag is provided, comprising a control
microcircuit configured to implement a basic function and a
cryptographic function; a sacrificial conductive track arranged
across a sacrificial area of the tag; and a circuit for detecting
continuity of the sacrificial track, cooperating with the
microcircuit to implement the basic function without implementing
the cryptographic function when the sacrificial track is
broken.
[0007] The microcircuit may be a standard microcircuit comprising a
programmable digital input/output pin, the sacrificial track being
connected between the input/output pin and a power supply pin of
the microcircuit, the microcircuit being programmed to test the
state of the input/output pin to determine the implementation of
the cryptographic function.
[0008] Alternatively, the tag may include an antenna circuit
configured to ensure a continuity detection function, the
sacrificial track being connected to the antenna circuit so that
its rupture shifts the frequency tuning of the antenna circuit, the
offset in the tuning frequency being selected such that the supply
power received by the microcircuit is lowered to a level
insufficient for implementing the cryptographic function, yet
sufficient for implementing the basic function.
[0009] The tag may include a compliant substrate tape; an antenna
included in the antenna circuit; a capacitor connected to the
antenna circuit; a sacrificial impedance; and the sacrificial track
running along the tape to connect the sacrificial impedance to the
antenna circuit.
[0010] The tag may include two metal surfaces facing each other on
opposite sides of the substrate in a region of interest of the
substrate, configured such that a piercing of the region of
interest causes a permanent short circuit between the two surfaces;
and a circuit configured to detect a short circuit between the two
metal surfaces.
[0011] Alternatively, the tag may include a sacrificial structure
including a conductive track connecting the sacrificial impedance
to the antenna circuit, the track configured in meanders occupying
a region of interest of the substrate so that a piercing of the
area of interest severs the conducting track.
[0012] The antenna may include turns wound in a ring around a
central area of the tape; the sacrificial impedance may be arranged
at a first end of the tape; and the sacrificial track may include a
loop extending to the second end of the tape.
[0013] The tag may include several tapes intersecting at the
antenna area, the sacrificial track forming a loop in each tape
segment extending from the antenna, except the tape segment
supporting the sacrificial impedance.
[0014] The tag may include several tapes intersecting at the
antenna area, the sacrificial track forming a loop in the tape
segment opposite the one supporting the sacrificial impedance.
[0015] A container may be provided comprising a cap and a tag of
the abovementioned type, wherein the substrate region bearing the
antenna has a smaller diameter than the cap, and is fixed by gluing
on the container and cap, so that the antenna is centered over
cap.
BRIEF DESCRIPTION OF DRAWINGS
[0016] Other advantages and features will become more clearly
apparent from the following description of particular embodiments
of the invention provided for exemplary purposes only and
represented in the appended drawings, in which:
[0017] FIG. 1 shows an embodiment of an anti-counterfeiting NFC tag
for a bottle;
[0018] FIG. 2 is an equivalent electrical block diagram of the
device of FIG. 1;
[0019] FIG. 3 shows a use case of the device of FIG. 1 on a wine
bottle;
[0020] FIG. 4 shows an alternative of the device of FIG. 1;
[0021] FIG. 5 shows another embodiment of an anti-counterfeiting
NFC tag for a bottle;
[0022] FIG. 6 shows a use case of the device of FIG. 5 on a wine
bottle;
[0023] FIG. 7 shows another embodiment of an anti-counterfeiting
NFC tag for a bottle;
[0024] FIG. 8 is an equivalent electrical block diagram of the
device of FIG. 7;
[0025] FIG. 9 shows an alternative of the device of FIG. 7;
[0026] FIG. 10 shows another embodiment of an anti-counterfeiting
NFC tag for a bottle;
[0027] FIG. 11 shows another embodiment of an anti-counterfeiting
NFC tag for a bottle; and
[0028] FIGS. 12 and 13 show an alternative of the tag of FIG. 11 in
two forms that are industrially feasible with current
technologies.
DESCRIPTION OF EMBODIMENTS
[0029] In the context of the aforementioned U.S. Pat. No.
7,898,422, once the bottle has been opened, the NFC device becomes
silent. However, the user may wish to consult the information
again, for example to share it with a friend, or visit the
producer's website to order new bottles.
[0030] A tag of the type described in US patent application
2005-0012616 does not differentiate the sealed or open state of a
container in the information returned by the tag. Indeed, the
information returned is the same, whatever the state of the
sacrificial antenna, provided the tag reader can supply the tag in
its antenna-less mode.
[0031] A double tag of the type described in the aforementioned US
patent application 2007-0210173 requires two independent NFC
circuits and two different steps for attaching the tag to the
object to protect, which increases the manufacturing cost.
Furthermore, each NFC circuit, being independent, preserves its
full functionality when interrogated by the tag reader.
[0032] Contactless anti-counterfeiting devices, for example of NFC
type, are provided hereinafter for containers, in particular
bottles or vials, in the form of tags that are inexpensive to
manufacture. In addition, the tags are designed to allow
authentication when intact, and mere reading and transmission of
information when they are broken following the opening of the
container. Indeed, when the container is opened, the user may
simply wish to read the information available in the contactless
device without performing an authentication.
[0033] FIG. 1 illustrates a first embodiment of an
anti-counterfeiting NFC tag which will be referred to as "dual
mode". The tag is in the form of a tape 10 of insulating material
serving as a substrate to form conductive tracks according to
common manufacturing techniques of RFID tags. One end of the tape
is enlarged to accommodate an NFC antenna 12 formed of several
turns of a conductive track.
[0034] A microcircuit 14 is mounted near the connection between the
tape 10 and the antenna 12 and is connected to the antenna
terminals by a track 12-1 on the same side as the antenna, and a
track 12-2 on the opposite side, joining the end of the inner turn
of the antenna through a via 16a. A via 16b couples the
microcircuit 14 to the track 12-2.
[0035] The microcircuit 14 is flip-chip assembled or fixed with a
conductive adhesive. The microcircuit integrates NFC device
management functions. Since the device can provide an
authentication function, it is an active device, that is to say,
the microcircuit integrates a microcontroller and cryptographic
functions. The microcircuit then draws its power from the energy
supplied to the antenna by an NFC reader, which can be a
smartphone, tablet, watch, etc. provided with an NFC interface.
[0036] Tracks 12-1 and 12-2 extend to the opposite end of the tape,
where they are respectively connected to two conductive surfaces
formed on both sides of the tape. These opposing conductive
surfaces form a sacrificial capacitor C1s.
[0037] The device is designed to be secured to a container, e.g. a
bottle, so that the central portion of the tape is placed across a
sealing element 18 of the container, for example a cork. It is
desired that the tape breaks while also severing the tracks 12-1
and 12-2 when the bottle is opened, that is to say when the cork 18
is pulled. For this purpose, the bond between the tape and the
container may be designed to have a rupture strength greater than
that of the tape. A high bonding strength may be obtained with
glue, and the required rupture strength may be ensured by gluing
the tape over a sufficient surface area.
[0038] The rupture strength of the tape may also be reduced by
providing breaking points 20 near the cork, as shown. Preferably,
these breaking points are located at the edge of the bonding area
of the tape, which causes a rupture-promoting stress.
[0039] The tape may be bound to the container by the face bearing
the majority of the conductive tracks. The adhesive force of the
tracks to the container is generally higher than the adhesive force
of the tracks to the tape. As a result, any attempt to remove the
tag causes tearing of the conductive tracks, which remain stuck to
the container.
[0040] The tracks are usually aluminum, making it difficult to
repair severed tracks by welding or brazing due to the insulating
oxide layer that forms on aluminum upon exposure to air.
[0041] FIG. 2 is an equivalent electrical diagram of the device of
FIG. 1. The microcircuit 14 may include a dedicated microcontroller
UC implementing the logic and analog functions of the microcircuit,
including supplying power to the circuit from the field supplied to
the antenna by an NFC reader, demodulation of signals transmitted
by the reader, modulation of the impedance of the antenna for
transmitting signals to the reader, and generation of secure keys
to authenticate the transmitted information.
[0042] The microcircuit further includes a capacitor C1 connected
across the antenna 12. The tracks 12-1 and 12-2 connect the
sacrificial capacitor C1s in parallel with the capacitor C1. The
antenna 12 and the capacitors C1 and C1s form an antenna circuit
whose tuning frequency is determined by the sum of the values of
the capacitors C1 and C1s, and by the inductance of the antenna.
These values are chosen to tune the antenna circuit to a typical
nominal frequency chosen for good interoperability between
standards compliant devices, e.g. 14 MHz.
[0043] When the sacrificial capacitor C1s is disconnected from the
antenna circuit after severance of the tape, the antenna circuit is
tuned to a frequency offset above the nominal frequency, e.g. 17
MHz, defined solely by the capacitor C1 and the inductance of the
antenna. As a result, the device may still be powered by the field
of a reader, but the transmitted power is lower.
[0044] To perform authentication operations, the microcontroller UC
of microcircuit 14 has cryptographic functions. The microcontroller
may include a general purpose processor CPU assisted by a
cryptographic coprocessor CCP.
[0045] Mere reading of information stored in the microcircuit and
transmission thereof by the antenna does not solicit the CPU very
much and requires little electrical power. The coprocessor CCP is
then not used. The current consumption may be less than 1 mA. This
power level can be provided even by an out of tune antenna
circuit.
[0046] A cryptographic operation, however, solicits both the CPU
and the coprocessor CCP, and may consume a current of several
milliamperes. This power level cannot be provided if the antenna
circuit is too severely out of tune, even when touching the tag
with the reader.
[0047] With these elements, assuming that C1+C1s is the value
required to obtain an antenna circuit tuned to the nominal
frequency, the value C1 is chosen so that, in the absence of
capacitor C1s, the antenna circuit is tuned enough to produce the
power required for mere reading and transmission of information,
but not enough to produce the power required by a cryptographic
operation.
[0048] In an example where the nominal frequency is 14 MHz, the
desired operation is obtained when the offset tuning frequency is
chosen near 17 MHz in a given technology.
[0049] The microcircuit may then be programmed to systematically
start with the production of information and end with the
cryptographic operations. Breaking the tape disconnects the
capacitor C1s from the antenna circuit, causing the tuning shift of
the antenna circuit. In this case, when the microcircuit starts the
cryptographic operations, the supply voltage collapses, causing a
reset of the microcircuit. The microcircuit reboots and starts the
same cycle again.
[0050] FIG. 3 shows an exemplary use case of an anti-counterfeiting
NFC tag of the type of FIG. 1 on a bottle of wine 30. (For clarity
of the figure, the spaces between elements have been exaggeratedly
enlarged.) The cork 18 is flush with the upper end of the bottle
neck. The central part of the tape 10 covers the cork 18
horizontally. The ends of the tape are folded down vertically to
fit the sides of the neck, and are fixed to the neck by a layer of
glue 34. The tape may be flexible enough to allow folding over the
top end of the neck and fit the radius of the neck. In this case,
the antenna is preferably planar.
[0051] A bottle of wine is usually provided with a protective cap
32 that covers the cork and the upper end of the neck. As shown,
the cap may also cover the tape 10. In this case, as the cap is
often metallic, it is preferable that the antenna 12 is outside the
cap so that it is exposed to electromagnetic fields. The length of
the tape 10 is chosen accordingly.
[0052] The NFC tag thus laid out can be read by a customer using
their NFC smartphone or other NFC reader. In particular, when the
tag is intact, they may proceed with an authentication using a
secure key available in the tag to confirm that the product
conforms to the information provided by the tag via an
authentication server and a dedicated application. They may also,
using the same application or a generic application, consult the
product's features, even when the anti-counterfeiting tag is
broken, including the type of information that may appear on a
paper label of the bottle. Several bottles of a same batch may have
tags sharing the same identifier or key.
[0053] The tracks 12-1, 12-2 of FIG. 1 can be relatively long and
form parasitic antennas that capture spurious electromagnetic
fields. When the tape 10 is wrapped in a metal cap (FIG. 3), the
cap offers protection from these magnetic fields. In other
situations, the cap may be transparent to the fields, or be
absent.
[0054] FIG. 4 illustrates an alternative of the tag of FIG. 1, less
sensitive to parasitic fields. The pair of tracks 12-1, 12-2 is
configured to form a twisted pair. For this purpose, for example,
the tracks 12-1 and 12-2 are not actually "twisted", but sinuous in
opposite phases.
[0055] Certain wine connoisseurs may wish to keep the cork, which
bears the main information relating to the wine. In this case, it
would be convenient that the active part of the NFC tag remains on
the cork, so that the connoisseur can get more detailed information
about wine by reading the information contained in the tag, using a
smartphone for example.
[0056] FIG. 5 shows an embodiment of an anti-counterfeiting tag
dedicated to this use. The NFC tag is designed so that its active
part, namely the antenna 12 and the microcircuit 14, remains fixed
on the upper end of the cork, and that this active part allows
reading information without authentication once the cork is
extracted.
[0057] The tag here includes a substrate in the form of two crossed
tapes 10a and 10b. The antenna 12 is arranged at the intersection
of the two tapes, and includes turns wound in a ring around a
sufficiently large central area for allowing a corkscrew to
penetrate without damaging the antenna. As shown, the central area
of the substrate may include an opening 50 to facilitate
penetration of the corkscrew and limit the deformation of the
substrate. The outer diameters of the antenna 12 and the annular
region of the supporting substrate are at most equal to the
diameter of the cork.
[0058] The tape segments or wings extending radially from the
antenna are designed to separate from the central area upon
extraction of the cork, and may include for this purpose breaking
points 20 in the vicinity of the outer diameter of the annular
region bearing the antenna. The microcircuit 14 and its connection
tracks to the antenna circuit are arranged within the annular
region of the substrate so that they do not remain on the tape
segments when the cork is extracted. The sacrificial capacitor C1s
is arranged at the distal end of one of the wings, here the right
wing that is part of tape 10a.
[0059] This structure is similar to that of FIG. 1, considering the
antenna and the right wing bearing the sacrificial capacitor C1s.
The additional wings render access to the cork more difficult
without breaking the tag. As shown, the track 12-1 may form a loop
in each of the three additional wings before joining the
corresponding pin of the microcircuit 14, so that the track is
severed when any of the wings is broken.
[0060] FIG. 6 shows an exemplary use case of an anti-counterfeiting
NFC tag of the type of FIG. 5 on a bottle of wine 30. (For clarity
of the figure, the spaces between elements have been exaggeratedly
enlarged.) The cork 18 is flush with the top end of the bottle neck
or is slightly recessed. The central annular part of the substrate
carrying the antenna 12 is adjusted on the upper end of the cork 18
and is secured thereto by a layer of glue 36. The wings of tapes
10a, 10b are folded down vertically to fit the sides of the neck,
and are fixed to the neck by a layer of glue 34.
[0061] To open the bottle, a corkscrew may be introduced through
the central opening 50 of the tag without damaging the antenna 12.
The extraction of the cork 18 breaks the wings, and therefore
removes the sacrificial capacitor C1s from the antenna circuit. The
active part of the tag, without the sacrificial capacitor C1s,
remains fixed on the upper end of the cork. This active part
remains operational for a simple reading of information, but not
for performing an authentication. Authentication is possible only
if the tag is intact, that is to say, fixed on a unopened
bottle.
[0062] A protective cap 32 generally envelops the upper end of the
neck, including the wings of tapes 10a, 10b. If the cap is
metallic, it preferably includes a portion 32-1 facing the antenna,
shown in gray, that is permeable to magnetic field. In order to
promote the passage of field lines at the periphery of the antenna,
the portion 32-1 preferably has a larger diameter than the antenna.
It shall be noted that this embodiment provides a discreet NFC tag,
which does not alter the appearance of the bottle, which is
something that some producers or manufacturers may desire.
[0063] The tag of FIG. 5 has been shown by way of example in the
form of two crossed tapes 10a and 10b forming four radial wings.
The number of wings may be arbitrary, but preferably at least equal
to two. All wings do not necessarily bear conductive tracks--for
instance, a tag may be provided with a first pair of opposite wings
bearing tracks, and a second pair of opposite wings without tracks.
The number of wings may be odd.
[0064] The anti-counterfeiting NFC tags of FIGS. 1 and 5 are
effective to identify bottles that have been opened and potentially
re-filled with a product of doubtful origin. However, they do not
detect the removal or replacement of content using a syringe, for
example using the Coravin.TM. process where the cork is pierced
with a syringe and the content is extracted while injecting an
inert gas into the bottle. Such a technique would leave the tag
intact.
[0065] FIG. 7 illustrates an embodiment of an NFC tag that can
detect a cork piercing attempt. The tag is made here on a substrate
of same cross-shape as the tag of FIG. 5. The central portion,
housing the antenna 12, however, has a larger diameter than the
cork. The antenna 12 is wound in a ring in the space between the
edge of the neck and the cork, thus leaving a central region of the
size of the cork, which central region forms a region of interest
to protect. This central region is used to form a sacrificial
capacitor C2s. The capacitor C2s is formed by two metal surfaces
facing each other, one formed on the upper face of the substrate
(in gray) and the other on the opposite face of the substrate (in
black). The metal surfaces are not shown the same size in order to
distinguish them in the figure--in practice they are the same size
and fill the region of interest corresponding to the top of the
cork. The microcircuit 14 is preferably also arranged in this
zone.
[0066] The antenna 12 and the sacrificial capacitor C2s are
connected in series in this embodiment. The lower surface of the
capacitor (in black) is directly connected to a first pin of the
microcircuit 14. A conductive track 70 connected to the upper
surface of the capacitor (gray) includes a loop extending into each
tape segment or wing extending radially from the central zone. The
last loop crosses the substrate through a via 72 and joins the
outer end of the antenna 12. The inner end of the antenna is
connected to the second pin of the microcircuit 14.
[0067] A tag of the type of FIG. 7 may be mounted on a bottle in
the manner shown in FIG. 6. The central area of the tag may be
glued over its entire surface on the cork. Any attempt to access
the cork then results in the piercing of the two metallic surfaces
of the sacrificial capacitor C2s. When piercing, the plastic
substrate between the two metal surfaces is compressed permanently,
while the metal of the upper surface stretches, following the
movement of the piercing object (a needle or corkscrew), and
reaches the lower surface. The lower surface, since it lies against
a glue layer that is generally harder than the substrate, deforms
less than the upper surface. This results in a crimping of the
deformed region of the upper metal surface with the lower metal
surface, so that the two surfaces of the capacitor become
permanently short-circuited, even upon extraction of the piercing
object. This short circuit also occurs when the metal surfaces of
the capacitor are aluminum, because aluminum is wrought in an inert
atmosphere to prevent oxide formation, and the areas put in contact
of both surfaces are devoid of oxide since they are protected by
the substrate.
[0068] This short-circuit of the sacrificial capacitor C2s may be
used to detune the antenna circuit so that the NFC device operates
in a degraded mode, i.e. so that it offers the reading functions,
but not the cryptographic functions.
[0069] The extraction of the cork moreover severs the wings and the
conductive track 70. This severance disconnects the antenna 12 from
the microcircuit, so that the NFC device becomes inoperative. The
tag is then silent.
[0070] FIG. 8 is an equivalent circuit diagram of the device of
FIG. 7. As previously indicated, the sacrificial capacitor C2s and
the antenna 12 are connected in series between the two pins of the
microcircuit 14. The antenna circuit thus includes the capacitor C1
of the microcircuit connected in series with the capacitor C2s and
the inductance of the antenna 12. When the capacitor C2s is
short-circuited, the antenna 12 is directly connected across the
capacitor C1.
[0071] Given these two configurations, the component values are
selected to achieve tuning to the desired nominal frequency when
the capacitor C2s is integral, and a tuning offset placing the
device in a degraded mode when the capacitor C2s is shorted. The
value of the sacrificial capacitor C2s is determined by the cork
diameter and the thickness of the substrate.
[0072] With a PET substrate of 38 microns typically used for RFID
applications and the diameter of a wine bottle cork (21 mm), a
capacitance of the order of 116 pF is obtained. Providing nine
turns for the antenna and a value of 104 pF for capacitor C1, a
tuning frequency on the order of 15 MHz is obtained, which is
sufficiently close to the desired nominal frequency of 14 MHz to
ensure all functions (reading and cryptography). When the capacitor
C2s is shorted, a tuning frequency of approximately 11 MHz is
obtained, just sufficient to ensure the reading functions.
[0073] FIG. 9 illustrates an embodiment of an NFC tag that can
detect a cork piercing attempt, in the same format as the tag of
FIG. 1, i.e. with an antenna 12 offset to an end of the tape. The
central portion of the tape that covers the cork 18 carries the
metal surfaces forming the sacrificial capacitor C2s. The
microcircuit 14 is mounted in series in the track 12-1 that extends
through the tape. This track further connects to the upper metal
surface of the capacitor C2s after forming a loop toward the distal
end of the tape. The lower metal surface of the capacitor is
connected to the track 12-2.
[0074] This embodiment offers greater latitude to realize the
antenna 12 than the embodiment of FIG. 7, and it allows covering
the cork integrally with metal surfaces. It may however be less
suitable in cases where it is desired to integrally hide the tag
under the cap.
[0075] FIG. 10 illustrates an alternative similar to the tag of
FIG. 1, which can also detect piercing attempts. In contrast to the
tag of FIG. 1, one of the connection tracks of the sacrificial
capacitor C1s, here track 12-1, has a compact meander-like
configuration occupying the entire surface area of the region of
interest to protect. The pitch of the meanders is preferably less
than the diameter of the needle that could be used for piercing, so
that the insertion of the needle severs the track in at least one
location. If the track 12-1 cannot be configured with a small
enough pitch, the second track 12-2, on the other side of the
substrate, may be configured into complementary meanders, such that
segments of track 12-2 are interleaved with segments of track 12-1,
virtually dividing the pitch by two.
[0076] This tag will operate in degraded mode, allowing only
reading of information, both when the cork is removed (breaking the
tape and the tracks 12-1 and 12-2), and when the cork is pierced
(breaking a track segment in the protected area).
[0077] The configuration of FIG. 10 can be transposed to the cross
configuration of FIG. 5 or 7 if a discreet tag is desired that can
remain on the extracted cork in order to read information.
[0078] Many variations and modifications of the embodiments
described herein will be apparent to the skilled person. To achieve
a controlled tuning offset of the antenna circuit upon tag rupture,
a sacrificial capacitor (C1s, C2s) was disclosed as a preferred
embodiment--equivalent techniques may of course be used leading to
a tuning offset of the antenna circuit, for example by using a
sacrificial inductor or other sacrificial impedance in place of the
sacrificial capacitor.
[0079] Controlling the component values of the antenna circuit to
achieve the desired tuning offset, i.e. for providing enough power
supply, when the tag is broken, for the reading functions but
insufficient power supply for the cryptographic functions, may be
difficult under certain conditions. A feature of the dual-mode
devices disclosed so far is that they can use an off-the-shelf
microcircuit 14 having only two undifferentiated pins, which could
in certain circumstances simplify the industrialization processes
and reduce costs.
[0080] Inside Secure sells NFC device management microcircuits
under the name VaultIC.TM. 152, which have five pins--two pins to
connect the antenna, a ground pin GND, a programmable digital
input/output pin IO, and a pin VCC that may be used to power the
microcircuit from a battery or to power other components from the
energy gathered from the antenna. Such a microcircuit may be used
in a dual-mode tag structure with fewer constraints on the
achievement of the two modes of operation in large-scale
manufacturing.
[0081] FIG. 11 schematically shows such an NFC tag structure,
offering complete functionality when it is undamaged, and limited
functionality without encryption when it is damaged. The
microcircuit 14 thus includes five pins, two of which are connected
to the antenna 12 in a configuration similar to that of FIG. 1. The
conductive tracks 12-1 and 12-2 of the previous figures, here
denoted 12'-1 and 12'-2 are separate from the antenna track 12 and
are respectively connected to one of the power supply pins, e.g.
the ground pin GND, and the input/output pin IO of the microcircuit
14. The tracks 12'-1 and 12'-2 may be on the same face of the tape
10 and are connected to one another at the distal end of the tape
to form a loop that crosses the sacrificial area, corresponding for
instance to the location of the cork 18.
[0082] In some VaultIC microcircuits, the input/output pin IO is
pulled to the supply line VCC by a resistor, whereby its logic
level is high when it is not connected. In the configuration of
FIG. 11, the IO pin is held at a logic low level by the loop 12'-1,
12'-2. When the loop is broken, the IO pin goes high.
[0083] Thus, the microcircuit 14 may be programmed to test the
level of the IO pin at each reading. When the level is low, i.e.
when the tag is undamaged, the program in the microcircuit may be
designed to run all expected operations, namely the production of
plaintext information and the execution of an authentication
operation using cryptography. When the level is high, i.e. when the
loop 12'-1, 12'-2 is open, the program of the microcircuit may be
designed to produce the plaintext information but omit the
authentication operation.
[0084] One of the tracks 12'-1, 12'-2 may be meander-like as in
FIG. 10, the other being placed on the opposite face of the tape.
This allows detecting the severance of the track by removal of the
tag or piercing of the cork, causing the authentication step to be
skipped.
[0085] In other applications, the input/output pin IO of the
microcircuit 14 may be used to detect a short-circuit rather than
an open circuit. Thus, in a configuration similar to that shown in
FIGS. 7 and 9, the IO pin may be connected to one of the metal
surfaces of the sacrificial capacitor C2s, the other metal surface
being connected to ground. A piercing of the cork is then
detectable through the permanent short-circuit between the metal
surfaces forming the sacrificial capacitor C2s. Then, in the
absence of piercing, the IO pin is high. When the capacitor is
pierced, it is shorted and pulls the IO pin to ground. In this
case, the microcircuit reacts to the states of the IO pin with
inverted logic compared to the previous applications.
[0086] FIG. 12 shows an alternative of the tag of FIG. 11. The
antenna 12 is arranged in the center of the tape so that it is
centered over the cork when the tag is in place on the neck of a
bottle. The microcircuit 14 is located inside the antenna winding.
The two wings on either side of the antenna are crossed by the loop
12'-1, 12'-2, so that the severance of one of the wings is
sufficient to interrupt the loop. Each of the wings may have, on
each of its edges close to the central portion, several transverse
cuts 20' serving as breaking points.
[0087] Such a tag may be attached to the bottle only by its wings.
When the bottle is opened, the wings will break when the user cuts
and removes the cap covering the cork and tag. The central portion
of the tag remains usable without the authentication function to
share the information it contains.
[0088] This FIG. 12 corresponds to an actual operational prototype
produced with an aluminum track technology. The diameter of the
central portion of the tag is 25 mm, which is the diameter of the
neck of a wine bottle. This technology, in its current state,
produces relatively large vias that may occupy a large surface area
of the central region of the antenna, which may be an obstacle to
manufacturing tags according to FIGS. 5 and 7, since those tags
require an uncluttered area at the center of the antenna.
[0089] FIG. 13 shows a tag prototype of the type of FIG. 12 made
with a copper track technology. This technology can produce tracks
and vias with smaller features than aluminum technologies, whereby
a wide central area may be released, making it easier to
manufacture tags of the type of FIGS. 5 and 7.
[0090] Tags with offset antennas (particularly those of FIGS. 1 and
11) may also be used on containers with metal closure members, by
providing the rear side of the tag at the antenna level with an
electromagnetic insulation layer such as ferrite.
[0091] From FIG. 11, a continuity detection technique has been
disclosed using the IO pin of the microcircuit 14, this detection
technique essentially including the observation of a permanent
change in the voltage level of the IO pin.
[0092] To counter some tag repair options, the microcircuit may be
designed to emit a pseudo-random logic sequence on the IO pin. The
sacrificial loop may then be connected between the pin IO and a
second input/output pin programmed to compare the incoming logic
sequence to the sequence transmitted on pin IO. If the microcircuit
detects that the incoming sequence differs from the transmitted
sequence, it can switch into the mode with restricted
functionality.
[0093] In practice, the realization of this type of detection
requires no additional circuitry. Indeed, microcircuits used in
this type of product are usually provided with an "active shield"
protecting the microcircuits from intrusion, as described in U.S.
Pat. No. 8,296,845, for example. An active shield generally
includes a dense network of conductive tracks realized on the last
metal level of the chip. The tracks receive on one end a logic
pseudo-random sequence, and circuitry collects the signals at the
other ends of the tracks to compare them to the expected signal.
The microcircuit may be programmed to take preventive measures when
a signal mismatch is detected.
[0094] The microcircuit may be readily modified in this case to
extend one of the active shield tracks through the input/output
pins and the sacrificial loop. The interruption of the sacrificial
loop then has the same effect as severing the active shield
track.
* * * * *