# US 11,307,635 B2 · Field-powered biometric device, and method of controlling a field-powered biometric device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,307,635 B2 - Document ID: US11307635B2 - Status: Granted - Kind: B2 - Application number: 16/609,573 - Filed: 2018-04-24 - Published: 2020-02-27 - Granted: 2022-04-19 - Earliest claimed: 2017-05-05 - Assignees: Fingerprint Cards Anacatum IP AB - Applicants: Fingerprint Cards AB - Inventors: Peter Almers; David Carling; Rolf Sundblad; Nicholas Weiner; Benjamin Willcocks - Web page: https://patentgrep.com/patent/US11307635B2 ## CPC - G06K 19/0723: {the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs} - G06F 1/10: Distribution of clock signals {, e.g. skew} - G06F 1/263: {Arrangements for using multiple switchable power supplies, e.g. battery and AC (G06F1/30 takes precedence)} - G06F 1/3206: Monitoring of events, devices or parameters that trigger a change in power modality - G06F 1/3243: {Power saving in microcontroller unit} - G06F 11/3024: {where the computing system component is a central processing unit [CPU]} - G06F 11/3062: {where the monitored property is the power consumption (power management in a computing system G06F1/3203)} - G06F 21/32: using biometric data, e.g. fingerprints, iris scans or voiceprints - G06F 21/602: {Providing cryptographic facilities or services} - G06F 21/6245: {Protecting personal data, e.g. for financial or medical purposes} - G06K 19/07: with integrated circuit chips - G06K 19/0712: {the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier (active means for hindering electromagnetic reading or writing G06K19/07336)} - G06K 19/0715: {the arrangement including means to regulate power transfer to the integrated circuit} - G06K 19/0718: {the sensor being of the biometric kind, e.g. fingerprint sensors (fingerprint sensors in general G06V40/13; biometric access-control systems in general, see G07C9/00)} - G06V 40/1306: {non-optical, e.g. ultrasonic or capacitive sensing} - H04B 5/26: using coils - H04B 5/45: Transponders - H04B 5/79: for data transfer in combination with power transfer - H04W 52/0261: {managing power supply demand, e.g. depending on battery level} - H04W 52/0296: {switching to a backup power supply} - Y02D 30/70: in wireless communication networks - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A method of controlling operation of a field-powered biometric device comprising biometric acquisition circuitry, processing circuitry controllable to transition between a first functional state having a first power consumption and a second functional state having a second power consumption lower than the first power consumption, and power management circuitry. The method comprises the steps of monitoring, by the power management circuitry, a property indicative of a supply voltage to the processing circuitry; controlling, when the monitored property indicates that the supply voltage has fallen to a first threshold voltage, the processing circuitry to transition from the first functional state to the second functional state; and controlling, when the monitored property indicates that the supply voltage has increased to a second threshold voltage higher than the first threshold voltage, the processing circuitry to transition from the second functional state to the first functional state. ## Claims ### Claim 1 A field-powered biometric device using electrical power harvested from a time-varying electrical field for acquiring and performing operations on a biometric representation of a user, said field-powered biometric device comprising: biometric acquisition circuitry for acquiring the biometric representation of the user; processing circuitry connected to said biometric acquisition circuitry for receiving the biometric representation from said biometric acquisition circuitry and performing said operations on the biometric representation, said processing circuitry being controllable to transition between a first functional state exhibiting a first power consumption and a second functional state exhibiting a second power consumption lower than said first power consumption; power management circuitry connected to said processing circuitry, said power management circuitry being configured to: monitor a property indicative of a supply voltage to said processing circuitry; control, when said monitored property indicates that said supply voltage has fallen to a first threshold voltage, said processing circuitry to transition from said first functional state to said second functional state; and control, when said monitored property indicates that said supply voltage has changed from said first threshold voltage to a second threshold voltage higher than said first threshold voltage, said processing circuitry to transition back from said second functional state to said first functional state, wherein: said processing circuitry is controllable to a third functional state in which said processing circuitry saves settings to prepare for shut-down to be able to resume operation when the supply voltage is later improved, and said processing circuitry erases cryptographic and/or biometric data stored by the field-powered biometric device in the third functional state; and said power management circuitry is further configured to: control, when said monitored property indicates that said supply voltage falls below a third threshold voltage lower than said first threshold voltage, said processing circuitry to transition from said second functional state to said third functional state. ### Claim 2 (depends on 1) The field-powered biometric device according to claim 1, wherein said processing circuitry is configured to: pause said operations on the biometric representation when being transitioned from said first functional state to said second functional state; and resume said operations on the biometric representation when being transitioned back from said second functional state to said first functional state. ### Claim 3 (depends on 1) The field-powered biometric device according to claim 1, further comprising an energy storage device arranged and configured to: receive current and store electrical energy when an available electrical power harvested from the electrical field is greater than a required electrical power needed for operation of said field-powered biometric device; and provide current to the processing circuitry when the available electrical power harvested from the electrical field is less than the required electrical power needed for operation of said field-powered biometric device. ### Claim 4 (depends on 3) The field-powered biometric device according to claim 3, wherein said energy storage device comprises a capacitor. ### Claim 5 (depends on 1) The field-powered biometric device according to claim 1, further comprising clock signal providing circuitry connected to said processing circuitry for providing a clock signal to said processing circuitry, said clock signal providing circuitry being configured to provide said clock signal with a constant clock frequency to said processing circuitry, regardless of whether the processing circuitry is in said first functional state or in said second functional state. ### Claim 6 (depends on 1) The field-powered biometric device according to claim 1, wherein said power management circuitry is further configured to: disconnect, when said monitored property indicates that said supply voltage has fallen to said first threshold voltage, said clock signal providing circuitry from said processing circuitry; and reconnect, when said monitored property indicates that said supply voltage has changed from said first threshold voltage to said second threshold voltage, said clock signal providing circuitry to said processing circuitry. ### Claim 7 (depends on 1) The field-powered biometric device according to claim 1, further comprising energy harvesting circuitry connected to said biometric acquisition circuitry, to said processing circuitry, and to said power management circuitry, for: interacting with said time-varying electrical field to transform wireless energy from the electrical field to AC-power in said field-powered biometric device; and converting said AC-power to DC-power. ### Claim 8 (depends on 7) The field-powered biometric device according to claim 7, wherein said energy harvesting circuitry comprises a coil for interacting with said time-varying electrical field, and a rectifier connected to the coil. ### Claim 9 (depends on 1) The field-powered biometric device according to claim 1, further comprising voltage limiting circuitry arranged and configured to limit said supply voltage to the processing circuitry to a maximum supply voltage higher than said second threshold voltage. ### Claim 10 (depends on 1) The field-powered biometric device according to claim 1, wherein: said processing circuitry comprises a cryptographic block; and said processing circuitry, in said third functional state, further erases any data in said cryptographic block. ### Claim 11 (depends on 1) The field-powered biometric device according to claim 1, wherein said biometric acquisition circuitry comprises a fingerprint sensing arrangement. ### Claim 12 A method of controlling operation of a field-powered biometric device comprising biometric acquisition circuitry, processing circuitry controllable to transition between a first functional state having a first power consumption and a second functional state having a second power consumption lower than said first power consumption, and power management circuitry, said method comprising the steps of: monitoring, by said power management circuitry, a property indicative of a supply voltage to said processing circuitry; controlling, when said monitored property indicates that said supply voltage has fallen to a first threshold voltage, said processing circuitry to transition from said first functional state to said second functional state; and controlling, when said monitored property indicates that said supply voltage has increased to a second threshold voltage higher than said first threshold voltage, said processing circuitry to transition from said second functional state to said first functional state, wherein: said processing circuitry is controllable to a third functional state in which said processing circuitry saves settings to prepare for shut-down to be able to resume operation when the supply voltage is later improved, and said processing circuitry erases cryptographic and/or biometric data stored by the field-powered biometric device in the third functional state; and said method further comprises the step of: controlling, when said monitored property indicates that said supply voltage falls below a third threshold voltage lower than said first threshold voltage, said processing circuitry to transition from said second functional state to said third functional state. ### Claim 13 (depends on 12) The method according to claim 12, wherein: when said monitored property indicates that said supply voltage has fallen to the first threshold voltage, said processing circuitry is controlled to pause operations on a biometric representation of a user; and when said monitored property indicates that said supply voltage has changed from said first threshold voltage to the second threshold voltage, said processing circuitry is controlled to resume said operations on the biometric representation of the user.