BIOMETRIC DEVICE WITH LOW POWER USAGE

Abstract

A biometrically authorisable device 102 comprises: a biometric sensor 130 for obtaining biometric data from a user; a control system 114, 128 for controlling the device, wherein the control system 114, 128 is arranged to provide access to one or more protected functions of the device 102 in response to identification of an authorised user via the biometric sensor 130; and an internal power source for powering the biometric sensor 130 and the control system 114, 128; wherein the control system 114, 128 is able to place the device 102 into a zero-power standby mode when the device 102 is not in use; and wherein the device comprises a movement sensor 16 for reactivating the device 102, the movement sensor 16 generating an electrical voltage in response to movements of the device 102 and the device 102 being arranged to reactivate in response to an electrical voltage relating to one or more types of movements of the device 102.

Claims

1. A biometrically authorisable device comprising: a biometric sensor for obtaining biometric data from a user; a control system for controlling the device, wherein the control system is arranged to provide access to one or more protected functions of the device in response to identification of an authorised user via the biometric sensor; and an internal power source for powering the biometric sensor and the control system; wherein the control system is able to place the device into a zero-power standby mode when the device is not in use; and wherein the device comprises a movement sensor for reactivating the device, the movement sensor generating an electrical voltage in response to movements of the device and the device being arranged to reactivate in response to an electrical voltage relating to one or more types of movements of the device.

2. A biometrically authorisable device as claimed in claim 1, wherein the one or more types of movements of the device that trigger reactivation include an acceleration or a deceleration movement that does not regularly occur during normal handling of the device whilst it is not in use.

3. A biometrically authorisable device as claimed in claim 1 or 2, wherein the one or more types of movements of the device that trigger reactivation include a tap of the device on a hard surface.

4. A biometrically authorisable device as claimed in claim 1, 2 or 3, wherein the one or more types of movements of the device that trigger reactivation include a repeated tap of the device on a hard surface.

5. A biometrically authorisable device as claimed in any preceding claim, wherein since the movement sensor generates an electrical voltage in reaction to a movement then the device is arranged to move out of the zero-power standby mode and be reactivated without any on-going supply of power from the internal power source to the control system in the zero-power standby mode.

6. A biometrically authorisable device as claimed in any preceding claim, wherein the movement sensor is a piezoelectric sensor such as a piezoelectric accelerometer, a piezoelectric sounder, or a piezoelectric microphone.

7. A biometrically authorisable device as claimed in claim 6, wherein the piezoelectric sensor is a piezoelectric sounder comprising a layer of piezoelectric material sandwiched between two electrodes.

8. A biometrically authorisable device as claimed in any preceding claim, comprising: an electrical switch forming part of a connection of the internal power source to the control system and/or the biometric sensor; wherein a change in state of the electrical switch reactivates the device; and wherein the electrical switch is activated by the electrical voltage generated by the movement sensor in response to the one or more types of movements of the device.

9. A biometrically authorisable device as claimed in claim 8, wherein the device is arranged so that an electrical voltage higher than a threshold level is required in order to trigger the electrical switch.

10. A biometrically authorisable device as claimed in any preceding claim, wherein the control system is arranged such that after reactivation of the device from the zero-power standby mode an additional authorisation is required before full use of the device is permitted.

11. A biometrically authorisable device as claimed in any preceding claim, wherein the device is arranged enter the zero-power standby mode after it has been left unused for a period of time.

12. A biometrically authorisable device as claimed in any preceding claim, wherein the device is arranged to enter the zero-power standby mode in response to interaction with the user.

13. A biometrically authorisable device as claimed in claim 12, wherein the interaction with the user is a movement detected via the movement sensor

14. A biometrically authorisable device as claimed in any preceding claim, wherein the device is arranged enter the zero-power standby mode in response to the movement sensor detecting certain movements that are associated with loss or theft of the device.

15. A biometrically authorisable device as claimed in any preceding claim, wherein the control system is arranged to identify movements of the device based on the electrical voltage output by the movement sensor when the device is activated, and to change the operating mode of the device in response to pre-set movements.

16. A biometrically authorisable device as claimed in any preceding claim, wherein the biometric sensor is a fingerprint sensor.

17. A biometrically authorisable device as claimed in any preceding claim, wherein the device is a smartcard.

18. A method for controlling a biometrically authorisable device comprising: a biometric sensor for obtaining biometric data from a user; a control system for controlling the device; an internal power source for powering the biometric sensor and the control system; and a movement sensor that generates an electrical voltage in response to movements of the device; the method comprising: providing access to one or more protected functions of the device in response to identification of an authorised user via the biometric sensor; placing the device in a zero-power standby mode when the device is not in use; and using an electrical voltage from the movement sensor relating to one or more types of movements of the device to trigger reactivation of the device and take it out of the zero-power standby mode.

19. A method as claimed in claim 18, comprising reactivating the device in response to an acceleration or a deceleration movement that does not regularly occur during normal handling of the device whilst it is not in use.

20. A method as claimed in claim 18 or 19, comprising placing the device in the zero-power mode in response to a pre-set movement associated with a theft or loss of the card and/or when the device has undergone a period of inactivity.

21. A method as claimed in claim 18, 19 or 20, comprising requiring renewed identification of the authorised used via the biometric sensor after the device is reactivated and taken out of the zero-power standby mode.

Description

[0047] Certain preferred embodiments on the present invention will now be described in greater detail, by way of example only and with reference to the accompanying drawings, in which:

[0048] FIG. 1 illustrates a circuit for a smartcard with a fingerprint sensor;

[0049] FIG. 2 illustrates a smartcard including an external housing; and

[0050] FIG. 3 illustrates a smartcard with a laminated card body.

[0051] By way of example the invention is described in the context of a fingerprint authorised smartcard that includes contactless technology and uses power harvested from the card reader as well as having a battery. These features are envisaged to be advantageous features of one application of a biometric device with a movement sensor, but are not seen as essential features. A smartcard may hence alternatively use a physical contact and/or be powered only by the battery, for example.

[0052] FIG. 1 shows the architecture of a smartcard 102 that is provided with the proposed movement sensor and zero-power off functionality. A powered card reader 104 transmits a signal via an antenna 106. The signal is typically 13.56 MHz for MIFARE and DESFire systems, manufactured by NXP Semiconductors, but may be 125 kHz for lower frequency PROX products, manufactured by HID Global Corp. This signal is received by an antenna 108 of the smartcard 102, comprising a tuned coil and capacitor, and then passed to a communication chip 110. The received signal is rectified by a bridge rectifier 112, and the DC output of the rectifier 112 is provided to processor 114 that controls the messaging from the communication chip 110.

[0053] A control signal output from the processor 114 controls a field effect transistor 116 that is connected across the antenna 108. By switching on and off the transistor 116, a signal can be transmitted by the smartcard 102 and decoded by suitable control circuits 118 in the sensor 104. This type of signalling is known as backscatter modulation and is characterised by the fact that the sensor 104 is used to power the return message to itself.

[0054] A movement sensor 16 is connected in an appropriate way to the processor 114, and the connection includes an electrical switch such as a transistor that is also linked with the battery (not shown) of the device. The movement sensor 16 generates an electrical voltage in response to some or all movements of the smartcard 102. This sensor 16 might be a piezoelectric sounder or a MEMs piezoelectric accelerometer, for example.

[0055] In order to avoid a drain on the battery when the smartcard 102 is not in use there is a zero-power standby feature. An electrical switch such as a transistor links the battery to the processor 114 and other elements of the electrical circuit of the smartcard 102. The processor 114 can disconnect the battery using the electrical switch when it is required to place the smartcard 102 into a zero-power standby mode. For example, this may be when the smartcard 102 has been inactive beyond a certain length of time, or when the user interacts with the smartcard 102 in a way that has been set up to prompt the zero-power standby mode. In one example a tap of the smartcard 102 on a hard surface with sufficient force will cause the processor 114 to switch from an active mode into a zero-power standby mode.

[0056] With the use of such a zero-power standby feature then there is no use of the battery when the card is not in use. This is to be contrasted with smartcards where the processor 114 is always watching for the user to use the fingerprint sensor 130 or otherwise interact with the card.

[0057] In order for a zero-power standby feature to be practical it is necessary to also have a convenient means for turning the card back on, and the proposed smartcard 102 uses the movement sensor 16 for this purpose. Since the movement sensor 16 generates an electrical voltage in response to a movement that it does not need the battery to be connected for it to be able to reactivate the processor 114. Instead, the electrical voltage can be used to activate the electrical switch that connects the battery with the processor 114 and other elements of the electrical circuit of the smartcard 102. In particular, the electrical switch can be a transistor which is switched from one state to another in reaction to the electrical voltage generated by the movement sensor 16. The threshold voltage that is required to activate the transistor can be set such that the smartcard 102 only moves out of the standby mode when there is a sufficiently positive movement, for example a tap of the smartcard 102 on a hard surface. The voltage should be calibrated in order to avoid an excessive frequency of inadvertent activation of the smartcard 102 whilst it is being carried by the user.

[0058] In order to add extra security then when the smartcard 102 moves from the zero-power standby mode to the active mode it also requires biometric authorisation, via the fingerprint sensor 130 in this case, before full access to protected functions of the smartcard 102 is permitted. As noted above when the smartcard 102 is active then it could be arranged so that a tap of the smartcard 102 on a hard surface will cause the processor 114 to switch from an active mode into the zero-power standby mode. When this feature is combined with the requirement for biometric authorisation after the card is reactivated from being in the zero-power standby mode then there is yet further security, since the user can quickly tap the card when they wish to ensure that the biometric security is active. In many situations it is possible to tap the card when a user feels that there is a risk of theft or for any reason becomes uncomfortable with the situation in relation to access to the secure features on the smartcard 102. In a further refinement of this the processor 114 can be arranged to associate certain movements with loss or theft of the smartcard 102 and to then deactivate the card by disconnecting the battery when such movements are detected.

[0059] For example, if a smartcard 102 is snatched from the user's hand then this will have a characteristic pattern of movement and acceleration of the card 102, which can be sensed by the movement sensor 16 and matched by the processor 114 to a preset sequence of movements that is deemed to require deactivation of the smartcard 102. In addition, with some types of movement sensors 16 it may be possible to detect movements characteristic of dropping of the smartcard 102, such as freefall followed by an impact. This could be another preset sequence of movements that is deemed to require deactivation of the smartcard 102 in order that if the card is inadvertently dropped then it cannot be picked up by an unauthorised user still in an active state.

[0060] Similar advantages in relation to theft or loss of the card can be obtained in a variation of the above feature in which rather than fully deactivating the card by disconnection of the battery at the electronic switch, the processor 114 simply cancels any existing biometric authorisation so that subsequent use of the card will require renewed biometric authorisation.

[0061] The movement sensor 16 might also be used to control operation of the smartcard 102 whilst the card is activated, in which case it senses movements of the card and provides an output signal to the processor 114, which is arranged to detect and identify movements that are associated with required operating modes on the card as discussed below.

[0062] The smartcard further includes a fingerprint authentication engine 120 including a fingerprint processor 128 and a fingerprint sensor 130. This allows for enrolment and authorisation via fingerprint identification. The fingerprint processor 128 and the processor 114 that controls the communication chip 110 together form a control system for the device. The two processors could in fact be implemented as software modules on the same hardware, although separate hardware could also be used.

[0063] The antenna 108 comprises a tuned circuit including an induction coil and a capacitor, which are tuned to receive an RF signal from the card reader 104. When exposed to the excitation field generated by the sensor 104, a voltage is induced across the antenna 108.

[0064] The antenna 108 has first and second end output lines 122, 124, one at each end of the antenna 108. The output lines of the antenna 108 are connected to the fingerprint authentication engine 120 to provide power to the fingerprint authentication engine 120. In this arrangement, a rectifier 126 is provided to rectify the AC voltage received by the antenna 108. The rectified DC voltage is smoothed using a smoothing capacitor and then supplied to the fingerprint authentication engine 120. In addition to the use of harvested power the smartcard also has a battery (not shown) that supplies power when harvested power is not available and also optionally can be used in parallel with the harvested power. In some cases the harvested power may be used to re-charge the battery and to thereby indirectly power other parts of the smartcard, rather than being used to power the sensor 16 and fingerprint authentication engine 120 directly.

[0065] The fingerprint sensor 130 of the fingerprint authorisation engine, which can be an area fingerprint sensor 130, may be mounted on a card housing 134 as shown in FIG. 2 or fitted so as to be exposed from a laminated card body 140 as shown in FIG. 3. The card housing 134 or the laminated body 140 encases all of the components of FIG. 1, and is sized similarly to conventional smartcards. The processor 128 comprises a microprocessor that is chosen to be of very low power and very high speed, so as to be able to perform fingerprint matching in a reasonable time.

[0066] The fingerprint authentication engine 120 is arranged to scan a finger or thumb presented to the fingerprint sensor 130 and to compare the scanned fingerprint of the finger or thumb to pre-stored fingerprint data using the processor 128. A determination is then made as to whether the scanned fingerprint matches the pre-stored fingerprint data. In a preferred embodiment, the time required for capturing a fingerprint image and authenticating the bearer of the card 102 is less than one second.

[0067] If a fingerprint match is determined and/or if appropriate movements are detected via the movement sensor 16, then the processor takes appropriate action depending on its programming. In this example the fingerprint authorisation process is used to authorise the use of the smartcard 104 with the contactless card reader 104. Thus, the communication chip 110 is authorised to transmit a signal to the card reader 104 when a fingerprint match is made. The communication chip 110 transmits the signal by backscatter modulation, in the same manner as the conventional communication chip 110. The card may provide an indication of successful authorisation using a suitable indicator, such as a first LED 136.

[0068] The fingerprint processor 128 and the processor 114 can receive an indication of a non-fingerprint interaction with the fingerprint sensor 130, which can include any action detectable via the fingerprint sensor 130 as discussed above. The interaction of the user with the card via the fingerprint sensor 130 are used as a part of a non-fingerprint authorisation and also may be used to allow the user to control the smartcard by switching between different operating modes of the smartcard.

[0069] In some circumstances, the owner of the fingerprint smartcard 102 may suffer an injury resulting in damage to the finger that has been enrolled on the card 102. This damage might, for example, be a scar on the part of the finger that is being evaluated. Such damage can mean that the owner will not be authorised by the card 102 since a fingerprint match is not made. In this event the processor 114 may prompt the user for a back-up identification/authorisation check via an alternative interaction with the smartcard 102, which in this case includes one or more action(s) detected via the fingerprint sensor 130 and also optionally actions detected via other sensors, such as the movement sensor 16. The card may prompt the user to use a back-up identification/authorisation using a suitable indicator, such as a second LED 138. It is preferred for the non-fingerprint authorisation to require a sequence of interactions with the card by the user, this sequence being pre-set by the user. The pre-set sequence for non-fingerprint authorisation may be set when the user enrols with the card 102. The user can hence have a non-fingerprint authorisation in the form of a password entered using non-fingerprint interactions with the card to be used in the event that the fingerprint authorisation fails. The same type of non-fingerprint authorisation can be used in the event that a user is unable or unwilling to enrol with the card 102 via the fingerprint sensor 130.

[0070] Thus, as well as allowing communication via the circuit 110 with the card reader 104 in response to a fingerprint authorisation via the fingerprint sensor 130 and fingerprint processor 128 the processor 114 may also be arranged to allow such communication in response to a non-fingerprint authorisation.

[0071] When a non-fingerprint authorisation is used the card 102 could be arranged to be used as normal, or it could be provided with a degraded mode in which fewer operating modes or fewer features of the card 102 are enabled. For example, if the smartcard 102 can act as a bank card then the non-fingerprint authorisation might allow for transactions with a maximum spending limit lower than the usual maximum limit for the card 102.

[0072] The processor 114 receives the output from the movement sensor 16 and this allows the processor 114 to determine what movements of the smart card 102 have been made. The processor 114 identifies pre-set movements and other actions of the user that are linked with required changes to the operating mode of the smartcard. As discussed above, the movements may include any type of or combination of rotation, translation, acceleration, impulse and other movements detectable by the movement sensor 16. The other actions of the user may include actions detected via the fingerprint sensor, such as taps, swipes and so on as discussed above.

[0073] The operating modes that the processor 114 activates or switches to in response to an identified movement associated with the required change in operating mode may include any mode of operation as discussed above, including turning the card on or off, activating secure aspects of the card 102 such as contactless payment, or changing the basic functionality of the card 102 for example by switching between operating as an access card, a payment card, a transportation smartcard, switching between different accounts of the same type (e.g. two bank accounts), switching between communications protocols (such as blue tooth, wifi, NFC) and/or activating a communication protocol, activating a display such as an LCD or LED display, obtaining an output from the smartcard 102, such as a one-time-password or the like, or prompting the card 102 to automatically perform a standard operation of the smartcard 102.

[0074] The processor 114 has an enrolment mode, which may be activated upon first use of the smartcard 102. In the enrolment mode the user is prompted to enrol their fingerprint data via the fingerprint sensor 130. This can require a repeated scan of the fingerprint via the fingerprint sensor 130 so that the fingerprint processor 128 can build up appropriate fingerprint data, such as a fingerprint template. After a successful or an unsuccessful enrolment of fingerprint data the user may be prompted to enter a non-fingerprint authorisation. This could be optional in the case of a successful fingerprint enrolment, or compulsory if the fingerprint enrolment was not successful. The non-fingerprint authorisation might include movements detected by the movement sensor 16. The processor 114 can keep a record of these interactions in a memory, and it is arranged to provide at least partial authorisation to use some of the functions of the card in the event that the non-fingerprint authorisation is provided by the user.

[0075] The processor 114 can have a learn mode to allow for the user to specify which actions (including combinations of actions/interactions) should activate particular operating modes whilst the smartcard 102 is in use. This type of control of the smartcard 102 might be enabled only after a successful fingerprint or non-fingerprint authorisation. In the learn mode the processor 114 prompts the user to make the desired sequence of actions, and to repeat the movements for a predetermined set of times. These movements are then allocated to the required operating mode or to the non-fingerprint authorisation. With this latter feature the learn mode can allow for the sequence of movements used for the non-fingerprint authorisation to be changed by the user in the same way that a traditional PIN can be changed.