CH713299B1 - Portable object comprising a near-field connection device. - Google Patents

Abstract

The present invention provides a portable object comprising a near-field communication device. The communication device comprises an electronic chip (1) provided with two terminals (2, 3) connected to an electrical circuit comprising an antenna (4) and a filter (5). The communication device is arranged to receive and transmit at a defined frequency corresponding to the resonance frequency of the electrical circuit. In an original manner, the portable object comprises a control member capable of being moved between two predefined positions, namely an active position in which the communication device is activated and a passive position in which the communication device is deactivated. The electrical circuit further comprises a branch branch (6) provided with a mechanical switch (7) capable of switching between an open state and a closed state in response to a movement of the control member from one to the other of its predefined positions by causing a modification of the resonance frequency of the electrical circuit.

Description

TECHNICAL AREA

[0001] The present invention relates to the field of microtechnology. It relates more particularly to a portable object comprising a near-field connection device.

PRIOR ART

[0002] It is known to produce portable objects incorporating near-field communication means, for example using a radio frequency tag. These connection means are composed of an electronic chip, or integrated circuit, electrically connected to an antenna. Most of the time, these devices do not need a standalone power supply and are intended to automatically communicate with a reader whenever they approach one. The electromagnetic field of the reader generates an induced current in the antenna which powers the chip and allows it in turn to emit a signal via the antenna.

[0003] Such devices are commonly found in smart cards which allow contactless payments to be made at the terminals provided for this purpose. We also know the applications EP 603 721, EP 974 878, CH 690 525 or CH 704 583 which describe watches comprising means of near field communication in which the antennas are hidden in different places of the watch such as the dial, the middle , the bezel, the window seal or the glass. Other configurations include housing the antenna in the back, the movement or even the bracelet. The integration of these contactless communication devices into a watch allows numerous applications such as carrying out information, identification, locking, access control or payment operations.

[0004] However, these automatic communication devices present a great vulnerability vis-à-vis malicious third parties who could, by approaching a transmitter receiver, recover confidential information without the knowledge of their owners or execute bank transfers to their profit. Different countermeasures have been developed to secure near-field communication devices. Payment cards can thus be placed in shielded cases which act like a Faraday cage and prevent communication from being established. Application US 2016/0188925 describes a method for activating or deactivating a radio frequency tag having an electronic switch using an appropriate auxiliary reader. The electronic unlocking operation can be tedious and impractical since it requires handling an object other than that through which communication is established. In addition, it presents a security vulnerability because the near-field communication device remains vulnerable between the moment it is activated and the moment communication is established. The various known security methods are unsuitable for certain portable objects such as a wristwatch, are impractical and do not completely eliminate the risk of hacking.

SUMMARY OF THE INVENTION

The present invention aims to propose a means for securing a near-field communication device integrated into a portable object which is easy to use and more secure than the solutions of the prior art.

[0006] More precisely, the invention relates to a portable object comprising a near-field communication device. The communication device comprises an electronic chip provided with two terminals connected to an electrical circuit comprising an antenna and a filter. The communication device is arranged to receive and transmit at a defined frequency corresponding to the resonance frequency of the electrical circuit. In an original manner, the portable object comprises a control member capable of being moved between two predefined positions, namely an active position in which the communication device is activated and a passive position in which the communication device is deactivated. The electrical circuit further comprises a branch branch provided with a mechanical switch capable of switching between an open state and a closed state in response to a movement of the control member from one to another of its predefined positions by causing a modification of the resonant frequency of the electrical circuit.

[0007] This arrangement makes it possible to secure a near-field communication device integrated into a portable object while simplifying the operations necessary for this security.

[0008] According to an advantageous variant of the invention, the electrical circuit comprises a bridge carrying a capacitor parallel to the antenna.

[0009] According to another advantageous variant of the invention, the antenna and the bridge are connected to the terminals of the electronic chip.

[0010] According to another advantageous variant of the invention, the branch branch is connected to the terminals of the electronic chip.

[0011] According to another advantageous variant of the invention, the bridge comprises a second component mounted in series with the capacitor and the branch branch is connected between the two components of the bridge and on a terminal of the electronic chip.

[0012] According to another advantageous variant of the invention, the second component is a capacitor or an inductor.

[0013] According to another advantageous variant of the invention, the branch branch comprises a component connected in series with the switch, the component being a capacitor, an inductor or a resistor.

According to another advantageous variant of the invention, an inductor is mounted between a terminal of the electronic chip and the capacitor and the branch branch is mounted parallel to the inductor.

[0015] According to another advantageous variant of the invention, the mechanical switch is a Reed switch and the portable object comprises a permanent magnet movable with reference to the Reed switch and capable of modifying the state of the Reed switch in response to a movement of the control member.

[0016] According to another advantageous variant of the invention, the portable object comprises a safety switch arranged to change state simultaneously with the Reed switch in the presence of an external magnetic field.

[0017] According to an advantageous variant of the invention, the portable object comprises an elastic return means arranged to automatically return the control member from the active position to the passive position.

[0018] According to another advantageous variant of the invention, the portable object is a watch.

[0019] According to another advantageous variant of the invention, the watch comprises a pivoting bezel which is the control member.

[0020] According to another advantageous variant of the invention, the watch comprises a crown or a pusher which is the control member.

[0021] According to another advantageous variant of the invention, the portable object is a smart card.

BRIEF DESCRIPTION OF THE FIGURES

[0022] Other details of the invention will appear more clearly on reading the description which follows, made with reference to the appended drawings in which: – Figures 1 to 7 represent different block diagrams of a communication device a portable object according to the invention, – Figure 8 represents a diagram of the gain of the antenna, therefore its performance, as a function of the frequency of a communication device according to the invention, – Figures 9 and 10 represent a sectional view of the branch branch and a switch, respectively in the open and closed positions.

DETAILED DESCRIPTION

[0023] Figures 1 to 7 represent block diagrams of the secure near-field communication device that the invention proposes to integrate into portable objects. The communication device comprises an electronic chip 1 provided with two terminals 2, 3 connected to an electrical circuit comprising an antenna 4 and a filter 5, typically a band-pass filter. The near-field communication device is arranged to receive and transmit at a defined frequency corresponding to the resonance frequency of the electrical circuit which is also the operating frequency of the reader with which the portable object is intended to communicate. The resonant frequency of the antenna is adapted in order to have the best performance (gain) in the useful frequency band, and therefore to allow reception and transmission in a controlled manner and according to the RFID standards in force. The electrical circuit comprises a branch branch 6 provided with a switch 7 capable of switching between an open state and a closed state. The switch 7 is controlled by the movement of a control member included in the portable object. The control member is able to be moved between two predefined positions, namely an active position in which the communication device is activated and a passive position in which the communication device is deactivated. Moving the control member from one of its predefined positions to the other causes the switch 7 to switch and modifies the resonance frequency of the electrical circuit and therefore its ability to communicate with a target reader.

[0024] In all the examples presented, the filter comprises a bridge 8 mounted in parallel with the antenna 4. It is also possible that this bridge is mounted in series, and that the other components are also placed in a dual manner to obtain similar effects, without departing from the scope of the invention. Only cases with a parallel bridge will be treated as an example in the remainder of the description.

[0025] In the examples of Figures 1 and 2, the bridge comprises only a capacitor 9, the antenna 4 and the capacitor 9 being connected to the terminals of the electronic chip 1. The branch branch 6 is also connected to the terminals 2, 3 of electronic chip 1, if switch 7 is in the closed position.

[0026] In the examples of Figures 3 to 6 the bridge comprises a second component 10 in addition to the capacitor 9 which can in particular be an inductor or a second capacitor. In this case the branch branch 6 is connected in parallel to the second component 10, on one side to a terminal 2 of the electronic chip 1 and on the other between the two components of the bridge 8.

The branch branch 6 may also include a component 11 connected in series with the switch 7, this component 11 possibly being a capacitor, an inductor or a resistor.

In the example presented in Figure 7, an inductor 12 is mounted between a terminal 3 of the electronic chip 1 and the capacitor 9 and the branch branch 6 is mounted parallel to the inductor 12.

[0029] Those skilled in the art will be able to create a large number of variants from the examples proposed by combining the different alternatives proposed with each other.

The diagram in Figure 8 represents the gain of the antenna of the communication device as a function of frequency in the case of a circuit with a band-pass filter. The central reception frequency of the passband is the resonance frequency fo of the electrical circuit. The transmission frequency of the reader is within the bandwidth of the circuit. Outside this reception range, the signal is too attenuated and the communication device can no longer function. In the case of an LC circuit comprising a capacitor and a coil, the resonance frequency is given by the formula: f0=1/2 π √LC

The modified circuit has a new resonance frequency f' sufficiently far from fo so that a signal emitted in the frequency range of the RFID device is no longer detected, thus deactivating the communication device.

[0032] Figures 9 and 10 represent a section of a detail of a portable object according to the invention, in this case a watch from which the case 20 can be seen. A bezel 21, pivotally mounted with reference to the case 20, comprises a near-field communication device such as those shown schematically in Figures 1 to 7 and comprising an antenna 4, an electrical circuit and an electronic chip. Flexible conductive blades 22, 23 housed in the housing 20 are arranged to come into contact with tabs 24, 25 of the electrical circuit when the bezel 21, which here is the control member, is in the active position shown in Figure 10 The flexible blades 22, 23 form a branch branch 6 which may optionally include an additional component 11, in particular a capacitor, an inductor or a resistor. When the control member is in the passive position shown in Figure 9, the branch branch 6 is connected to the electrical circuit via the tabs 23, 24 which has the effect of modifying the resonance frequency and making the device inactive. The portable object also includes an elastic return means 26 arranged to automatically return the control member to its passive position and thus secure the device.

The embodiment of a switch in Figures 9 and 10 is only a non-limiting example. Those skilled in the art will know how to adapt other devices to achieve this function. In particular, the control member can be a push button or the control crown. In an interesting configuration, the galvanic switch described above can be replaced by a flexible blade magnetic switch of the Reed switch type. In this case, the portable object also includes a permanent magnet movable with reference to the Reed switch 26, the relative movement of the Reed switch and the magnet being caused by the movement of the control member. As before, the assembly is arranged so that the movement of the control member, between its predefined positions, modifies the state of the Reed switch.

[0034] In a variant embodiment not shown, the portable object comprises a main Reed switch as well as an additional safety switch intended to protect against the risk of a fraudulent connection using a reader and a magnet placed by a malicious third party near the portable object. This safety magnet is also a reed switch. Unlike the main reed switch, the safety switch is not associated with a permanent magnet because it is not intended to change state during normal operation but only in the event of an attack.

The safety switch can, for example, be mounted in series with the main reed switch. The safety switch is in this case an NC type switch, normally closed, that is to say that it is closed in the absence of a magnetic field and that it switches to the open position under the effect of a magnetic field. The main reed switch is NO type, normally open, and operates in the opposite way to the previous one. In the event of an attack using a magnet, the safety switch and the main switch switch simultaneously under the influence of the external magnetic field, so that the communication device remains inactive. Preferably the main reed switch and the safety switch are arranged as close as possible, ensuring that the movement of the permanent magnet, controlling the main switch, has no effect on the safety switch.

[0036] A person skilled in the art will be able to make multiple variations from the embodiments presented without departing from the scope of the claims. The passive position of the control member can for example correspond to an open state of the switch as well as to a closed state.

[0037] The portable objects according to the invention offer great ease of use and better security than those provided with electronic switches of the prior art whose change of state must be controlled in advance from an electronic device externally, for example from a smartphone. It is possible to easily adapt this secure near-field communication device to any type of portable object such as a smart card, for example.

[0038] Advantageously, the security device proposed by the invention makes it possible to reduce the risks of fraudulent communication because the device can be activated while the portable object is already in the vicinity and under the magnetic influence of the reader with which it is intended to communicate, so that communication is instantly established with the target reader as soon as the control member is moved to the active position. In addition, the automatic return of the control member to its passive position immediately secures the device as soon as the desired operation has been carried out and even though the portable object is still within the range of the magnetic field of the target reader.

[0039] Furthermore, the mechanical locking means proposed by the invention gives the user control over the security of the near-field communication device and provides him with the confidence which was hitherto lacking in the use of this technology.

Claims (15)

1. Portable object comprising a near-field communication device, the communication device comprising an electronic chip (1) provided with two terminals (2, 3) connected to an electrical circuit comprising an antenna (4) and a filter (5) , the communication device being arranged to receive and transmit at a defined frequency corresponding to the resonance frequency of the electrical circuit characterized in that the portable object comprises a control member capable of being moved between two predefined positions, namely a position active in which the communication device is activated and a passive position in which the communication device is deactivated and in that the electrical circuit comprises a branch branch (6) provided with a switch (7) capable of switching between a state open and a closed state in response to a movement of the control member from one to the other of its predefined positions by causing a modification of the resonance frequency of the circuit. 2. Portable object according to claim 1, characterized in that the electrical circuit comprises a bridge (8) parallel to the antenna (4), carrying a capacitor (9). 3. Portable object according to the preceding claim, characterized in that the antenna (4) and the bridge (8) are connected to the terminals (2, 3) of the electronic chip (1). 4. Portable object according to one of the preceding claims characterized in that the branch branch (6) is connected to the terminals (2, 3) of the electronic chip (1). 5. Portable object according to one of claims 2 and 3 characterized in that the bridge (8) comprises a second component (10) mounted in series with the capacitor (9) and in that the branch branch (6) is mounted in parallel with the second component (10) by being connected on one side to a terminal (2) of the electronic chip (1) and on the other between the two components of the bridge (8). 6. Portable object according to the preceding claim characterized in that the second component (10) is a capacitor or an inductor. 7. Portable object according to one of the preceding claims characterized in that the branch branch (6) further comprises a component (11) connected in series with the switch (7), the component (11) being a capacitor, an inductance or resistance. 8. Portable object according to claim 2 characterized in that an inductor (12) is mounted between a terminal (3) of the electronic chip (1) and the capacitor (9) and in that the branch branch (6) is mounted parallel to the inductance (12). 9. Portable object according to one of the preceding claims characterized in that the switch (7) is a Reed switch and in that the portable object comprises a permanent magnet movable with reference to the Reed switch and capable of modifying the the state of the Reed switch in response to a movement of the control member. 10. Portable object according to claim 9 characterized in that it comprises a safety switch arranged to change state simultaneously with the Reed switch in the presence of an external magnetic field. 11. Portable object according to one of the preceding claims, characterized in that it comprises an elastic return means (26) arranged to automatically return the control member from the active position to the passive position. 12. Portable object according to one of the preceding claims characterized in that the portable object is a watch. 13. Portable object according to the preceding claim characterized in that it comprises a pivoting bezel (21) and in that the control member is the bezel (21). 14. Portable object according to claim 12 characterized in that it comprises a crown or a pusher and in that the control member is the crown or the pusher. 15. Portable object according to one of claims 1 to 11 characterized in that the portable object is a smart card.