Improved RF device

The present invention relates to a radio frequency (RF) device, a method of operating such a device and a system comprising such a device.

The use of smart card technology has evolved to such an extent that it has become an every-day item used in a large number of situations, such as identification and authorization means when requesting access to, e.g., a bank account via an ATM, when requesting entry via a building entrance locked by means of an electronic lock or when starting a vehicle whose engine starting mechanism is protected by an electronic lock.

One specific subset of smart cards is that of contact-less radio frequency smart cards. Such cards are activated by an RF field produced by a terminal, typically being integrated within an access control or authorization mechanism as exemplified above. The cards comprise a control unit, usually referred to as a Smart Card Controller (SCC), which typically holds private and proprietary information, and which is integrated in the card together with a coil inductor antenna. The coil inductor antenna is used to draw necessary supply of power for operation from the RF electromagnetic field provided by the terminal. Additionally, through the same RF field the SCC is communicating modulated information with the terminal. The mechanism is standardized as described, e.g., in ISO/IEC 14443.

A drawback related to state of the art contact- less RF smart cards is due to the fact that the coil antenna is in permanent connection with the SCC. Such a card is configured to communicate information that is stored in the card to a terminal whenever the card is placed within reach of an appropriately configured RF electromagnetic field, irrespective of whether or not a user/owner of the card is aware of such an RF field being present. This means that it is difficult for a user/owner to have total control over access to the information stored on the card.

A second development is the extension of the functionalities of smartcards, where the so-called multi- component cards contain additional circuitry for fulfilling additional functions to that of the controller. Examples of those are input functions like buttons, fingerprint sensors and other sensors and output functions like displays and sound generators. For operation of these functions the additional circuitry usually requires power and communication with the smartcard controller. Power solutions for cards, when not in a

contact terminal, are seriously limited by the available space for an in-card battery, whereas battery-free solutions in RF communication are hampered by power saving methods implemented by smartcard controllers, e.g. switching off external IO's to save power.

UK patent application publication 2407187 discloses a plurality of ways in which unauthorized access to a contact- less RF smart card is prevented. Entry of a PIN, sensing a fingerprint, sensing light, pressure and movement as well as RF shielding are examples of how to disable the card and thereby prevent unauthorized access.

An object of the present invention is to overcome drawbacks related to prior art arrangements as discussed above. This object is achieved in different aspects by way of a smart card, a method of operating a smart card and a system according to the appended claims.

Hence, in a first aspect, the present invention is a radio frequency (RF) device, preferably a contact-less smart card, comprising a control unit and an inductor configured to be connected to the control unit and configured to interact with a radio frequency electromagnetic field and thereby convey energy and/or modulated information to the control unit. The contact-less radio frequency smart card also comprises switching means that are configured to at least switch the inductor between a state of being connected to the control unit and a state of being disconnected from the control unit.

This is advantageous in that it is simple. By controlling the switching means to disconnect the inductor from the control unit, which typically will contain stored private and proprietary information, access is prevented without need for complicated means and procedures, such as detecting a fingerprint or interpreting a PIN code entry etc. as in prior art solutions.

In preferred embodiments, the RF device further comprises auxiliary circuitry where the switching means are configured to switch the inductor between a state of being connected to the control unit and a state of being connected to the auxiliary circuitry and/or to switch the control unit between a state of being connected to the inductor and a state of being connected to the auxiliary circuitry. For example, the auxiliary circuitry may comprise an input/output unit, such as a display unit, and a power unit and the power unit may further comprise a battery.

That is, either the inductor or the control unit are switched to the auxiliary circuitry, or both. This allows the auxiliary circuitry to communicate with the control unit via the RF terminals, which are the only ones functional when in contact-less operation. Moreover it reduces the interconnect between the auxiliary circuit and the control unit to the

bare minimum. The auxiliary circuit will then have supply power to the control unit through the antenna (i.e. inductor) connections or other means, which power could originate from a battery or from the power that the auxiliary circuitry gets from the inductor. At the same time the auxiliary unit gets connection to the inductor for communication to a terminal and/or for generating power from the terminal signal and/or for a separate inductor for its internal usage (e.g. an inductor in a DC:DC converter).

Such embodiments have an advantage in that they overcome a drawback related to state of the art RF devices that are equipped with auxiliary circuitry needing electric power also when the device is not placed within reach of an appropriate RF electromagnetic field capable of providing power to the device. A typical example of such circuitry is a display that is configured to, e.g., provide a visual indication relating to the information stored in the SCC. Such a device needs a power source to operate when the device is not in the RF field of a communication terminal. Typically, a power source is realized as a battery integrated into the device. However, such a battery delivers a voltage which typically does not match the required voltage for the SCC, implementing a communication protocol such as ISO/IEC 14443 or ISO/IEC 7816 (the interface with the controller could also follow ISO/IEC 7816 or other, ISO/IEC 14443 being the preferred). Therefore, a DC:DC converter is necessary, with the concomitant need for an inductor. Typically, such an inductor is bulky at least in relative terms when considering the small size of a device such as a smart card. By connecting the already existing inductor via the switching means to the auxiliary circuit, e.g. the power unit, a substantial amount of space can be saved on the smart card or, conversely, a smaller device can be manufactured. Moreover a DC:DC converter based on a inductor is more efficient than the ones without, which makes more efficient usage of the limited power available in the device. In a further embodiment the auxiliary circuitry contains a battery circuit that converts surplus power that is caught by the inductor to DC voltage, which is fed to the (rechargeable) battery. For example, the surplus energy in the RF field of a terminal could be used during a transaction and/or after a transaction is completed. Nevertheless, other available RF energy could be used continuously, both unintentional fields or intentional fields like in a "RF smartcard battery charger", which may be in the form of a terminal without an information stream.

For a battery-free solution in an RF field the auxiliary circuitry may contain a power block that extracts power from the inductor to feed the total auxiliary circuitry and the control unit, whereas the connection between the control unit and the auxiliary circuitry could

be used to have the control unit write information on a display screen that is part of the auxiliary circuitry.

In another embodiment, the RF device further comprises an input unit, e.g. in the form of a sensor, connected to any of the control unit and the auxiliary unit configured to detect a signal from the input unit and in response to the signal control the switching means.

That is, by providing an input unit such as a touch sensor, light sensor etc., it is possible to detect whether or not the device is physically in the hands of a person and thereby indicate a desire to use the device to communicate via an RF field. In other words, it is possible to control whether the antenna coil (i.e. the inductor) is to be connected in case the device is hand- held, or disconnected when it is not hand- held, e.g. when the device is stored in a wallet. A light sensor may be used to control the usage to situations where the antenna is connected only when the device is in a lighted environment.

Complementing the first aspect of the invention, a second aspect is that of a method of operating a radio frequency device, preferably a contact-less smart card, as discussed above. Such a method comprises the procedure of switching the inductor between a state of being connected to the control unit and a state of being disconnected from the control unit.

In preferred embodiments of such a method where the RF device comprises auxiliary circuitry, the inductor is switched between a state of being connected to the control unit and a state of being connected to the auxiliary circuitry and/or the control unit switched between a state of being connected to the inductor and a state of being connected to the auxiliary circuit.

Furthermore, where the auxiliary circuitry comprises a power unit the method may comprise switching the inductor between a state of being connected to the control unit and a state of being connected to the power unit, and controlling the power unit to charge the battery.

In a preferred embodiment, where the device comprises an input unit, the method comprises detecting a signal from the input unit, and controlling the switching means in response to the detected signal. In a third aspect, the invention provides a system comprising a RF device as discussed above and a radio frequency transceiver arrangement.

The invention will now be described by way of illustrative examples with reference to the accompanying drawings, where:

Figure 1 is a schematically illustrated block diagram of a system comprising a smart card and a terminal according to the present invention. Figure 2 is a schematically illustrated block diagram of an embodiment of a smart card according to the present invention.

Figure 3 is a schematically illustrated block diagram of another embodiment of a smart card according to the present invention.

Figure 4 is a schematically illustrated block diagram of yet another embodiment of a smart card according to the present invention.

Figure 5 is a schematically illustrated block diagram of yet another embodiment of a smart card according to the present invention.

Figure 1 shows a system 100 comprising a contact- less radio frequency (RF) smart card 102 and an RF transceiver arrangement 110. The RF transceiver arrangement 110 comprises a control device 118, typically a computer running appropriate software for controlling communication in the system 100, a transceiver 112 that establishes an RF electromagnetic field 116 via an antenna 114. In a typical implementation, the RF transceiver arrangement 110 is configured such that it forms a single unit that usually is referred to as a terminal. No further details will be discussed relating to specific details of the operation of the RF transceiver arrangement 110, as this is outside the scope of the present invention. Details regarding the operation of the RF transceiver arrangement 110 may, e.g., be found in the specifications of the standard ISO/IEC 14443. The contact- less RF smart card 102 of the system 100 comprises an antenna in the form of a coil inductor 104. Although not visible in figure 1, the coil inductor 104 typically comprises a conductive wire or lead that is wound a number of turns along the periphery of the smart card 102, and provides a specific inductance value between it's two ends as the skilled person will realize. The inductor 104 is connected to switching means 106 that also connects to a control unit 108. Usually, the control unit 108 is referred to as a smart card controller (SCC).

As already discussed above, by controlling the switching means 106 to be disconnect the inductor 104 from the control unit 108, which typically will contain stored private and proprietary information, access by the terminal 110 to the information stored in

the SCC 108 is prevented. In the example shown in figure 1, the switching means 106 will disconnect the inductor 104 from the SCC 108 as a response to a signal from the SCC, typically due to control operations performed by the SCC 108 when communicating with the terminal 110. However, as will be discussed further below, the control of when the switching means 106 are to disconnect the inductor 104 from the SCC 108 may be controlled in other ways.

As the skilled person will realize, the switching means 106 may be realized by any appropriate state-of-the-art active switching circuitry, such as bi-directional FETs or MEM devices etc. Turning now to figure 2, another embodiment of a contact-less RF smart card

202 will be described. Similar to the smart card 102 described with reference to figure 1, the smart card 202 comprises an antenna in the form of a coil inductor 204, switching means 206 and a control unit (SCC) 208. Auxiliary circuitry 220 is also connected to the switching means 206. As will be discussed further below, the auxiliary circuitry 220 may comprise a display or any other appropriate circuitry. Similar to the example described above, the switching means 206 will disconnect the inductor 204 from the SCC 208 as a response to a signal from the SCC. The switching means 206 may be configured such that it is capable of creating any cross connection between the inductor 204, the auxiliary circuitry 220 and the SCC 208 or only part of those. That is, the inductor 204 may be switched into connection with the auxiliary circuitry 220 while being disconnected from the SCC 208. Likewise, the inductor 204 may be switched into a disconnected state with respect to both the auxiliary circuitry 220 and the SCC 208, while the SCC 208 is switched into connection with the auxiliary circuitry 220. The control of when the switching means 206 are to perform the connect and disconnect operations may be controlled by any of the SCC 208 and the auxiliary circuitry 220.

Turning now to figure 3, a more detailed example of a smart card 302 configured with auxiliary circuitry 320 will be presented. Again, similar to the smart cards 102, 202 described with reference to figures 1 and 2, the smart card 302 comprises an antenna in the form of a coil inductor 304, switching means 306 and a control unit (SCC) 308. The auxiliary circuitry 320 is also connected to the switching means 306.

Here, the auxiliary circuitry 320 comprises a DC power unit 322 with a battery 324 and a display unit 326. As in the example discussed in connection with figure 2, in addition to be capable of disconnecting the inductor 304 from any of the circuitry on the card 302, the switching means 306 is also configured such that it is capable of creating the

necessary connections, part of any cross connection possible, between the inductor 304, the DC power unit 322, the display unit 324 and the SCC 308. For example, the inductor 304 may be switched to be in connection with the DC power unit 322 and thereby form a part of it's circuitry providing a suitable DC power level to the display unit 326 (and the SCC) in a situation where the display unit 326 is presenting information to a viewer. Simultaneously the SCC could be switched to the display unit, allowing it to exchange the information that needs to be displayed to the display. The inductor 304 may also be used together with the DC power unit 322 during a battery replenishing operation, during which the display 326 typically is disconnected from the DC power unit 326. The actual control of when the switching means 306 are to perform the connect and disconnect operations may be controlled, in addition to any of the SCC 308 and the auxiliary circuitry 320, also by the SCC 308 in response to a signal generated by a sensor 328 that is connected to the SCC 308 or to the auxiliary circuitry 320 (not drawn). The sensor 328 may be in the form of a touch sensor, light sensor etc. It is then possible to detect whether or not the smart card 302 is physically in the hands of a person and thereby indicate a desire to use the card to communicate. A light sensor may be used to control the usage to situations where the inductor 304 is connected only when the smart card 302 is in a lighted environment.

Figure 4 illustrates another embodiment of a smart card 402 configured with auxiliary circuitry 420. Here, the switching means are illustrated schematically as a number of terminals 406a, 406b, 406c and 406d configured as a double switch allowing switching of the auxiliary circuitry 420 in series with an inductor 404 to controller 408 connection or completely removing the auxiliary circuitry 420 from that connection.

The auxiliary circuitry 420 comprises a power block 432 that converts energy received by the inductor 404 from an RF field (not shown in figure 4) to power for use within the auxiliary circuitry 420 and for feeding the controller 408.

As illustrated in figure 4, the auxiliary circuitry 420 may also comprise a modem 430 allowing communication between the auxiliary circuitry 420 and the terminal (not shown in figure 4) via the inductor 404. Furthermore, the auxiliary circuitry 420 may also contain a second modem 434 configured for communication between the auxiliary circuitry 420 and the controller 408. This second modem 434 is configured for feeding power to the controller 408 using either AC or DC.

Figure 5 illustrates yet another embodiment of a smart card 502 configured with auxiliary circuitry 520. Here, the switching means are illustrated schematically as a

number of terminals 506a, 506b, 506c, 506d and 506e configured as a double switch allowing switching of auxiliary circuitry 520 in series with the inductor 504 to controller 508 connection or completely removing the auxiliary circuitry 520 from that connection.

As illustrated in figure 5, the auxiliary circuit may comprise a splitter 540 that is configured to split a signal received via the inductor/antenna 504 into that for use by the auxiliary circuitry 520 and into that for the power of the controller 508.

The signal for use by the auxiliary circuitry 520 is fed to a power supply 541 capable of supplying the auxiliary circuitry 520 with power.

As illustrated in figure 5, the signal for use by the auxiliary circuitry 520 may be fed to a modem 542 for allowing communication between a terminal (not shown in figure 5) and the auxiliary circuitry 520.

A signal intended for the controller 508 is fed through a filter 544 that blocks a data part of the signal but allows the carrier wave to pass through. This filter 544 may typically be in the form of a passive high pass filter. The carrier wave contains the power to drive the controller 508.

At the controller side, i.e. at the switch terminals 506d and 506e, the forwarded carrier wave is modulated in a modulator 546 and demodulated in a demodulator 548 for communication between the controller 508 and the auxiliary circuitry 520. In a typical implementation, the switching means may be configured such that switching between the modulator 546 and the demodulator 548 is allowed.

Hence, in summary, a contact-less radio frequency smart card comprises a control unit and an inductor configured to be connected to the control unit and configured to interact with a radio frequency electromagnetic field and thereby convey energy and modulated information to the control unit. The contact-less radio frequency smart card also comprises switching means that are configured to at least switch the inductor from being connected to the control unit to being disconnected from the control unit.