# US 2014/0152420 A1 · Capacitive data transfer in an electronic lock and key assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152420 A1 - Document ID: US20140152420A1 - Status: Published application - Kind: A1 - Application number: 13/706,267 - Filed: 2012-12-05 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: Knox Company - Applicants: Knox Company - Inventors: Keith T. Wolski - Web page: https://patentgrep.com/patent/US20140152420A1 ## CPC - G07C 9/00182: {operated with unidirectional data transmission between data carrier and locks} - G05B 1/01: electric - G07C 9/00309: {operated with bidirectional data transmission between data carrier and locks} - G07C 2009/00769: {with data transmission performed by wireless means} - G07C 2009/00777: {by induction} - Y10T 70/7136: Key initiated actuation of device - Y10T 70/7441: Key - Y10T 70/8081: Electric - G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An electronic key may include a partial capacitor comprising a capacitive metal plate in communication with a processor. The capacitive metal plate of the partial capacitor is configured to form a capacitor with a corresponding capacitive metal plate of a lock when brought into proximity with the metal plate of the lock. Data may be transferred from the key to the lock using a capacitor formed by combining the two metal plates, wherein a common ground is established between the metal plate of the key and the metal plate of the lock through a parasitic capacitance present between the key and lock circuitry. ## Claims ### Claim 1 An electronic key comprising: a housing; a power source disposed within the housing; a processor in communication with the power source; and a partial capacitor comprising a first capacitive metal plate in communication with the processor, the first capacitive metal plate of the partial capacitor configured to form a capacitor with a corresponding second capacitive metal plate of a lock when brought into proximity with the second capacitive metal plate of the lock; wherein the processor is programmed to transfer data signals at least partially by using the partial capacitor. ### Claim 2 (depends on 1) The electronic key of claim 1, wherein the first capacitive metal plate comprises an annulus. ### Claim 3 (depends on 2) The electronic key of claim 2, wherein the annulus comprises a front surface that lies in a plane substantially perpendicular to a longitudinal axis of the key. ### Claim 4 (depends on 2) The electronic key of claim 2, wherein the annulus comprises a gap configured to inhibit electrical current in the annulus. ### Claim 5 (depends on 1) The electronic key of claim 1, wherein the first capacitive metal plate comprises an electrical contact tab that is in electrical communication with the processor. ### Claim 6 (depends on 1) The electronic key of claim 1, further comprising a dielectric cover covering at least a portion of the first capacitive metal plate. ### Claim 7 (depends on 2) The electronic key of claim 2, further comprising a key power coil. ### Claim 8 (depends on 7) The electronic key of claim 7, wherein the key power coil and the first capacitive metal plate are concentric. ### Claim 9 (depends on 8) The electronic key of claim 8, further comprising a nose portion disposed within a hole formed by the annulus, wherein the key power coil is disposed at least partially within the nose portion. ### Claim 10 (depends on 7) The electronic key of claim 7, wherein the electronic key is configured to simultaneously transfer data using the first capacitive metal plate and transfer power using the key power coil. ### Claim 11 (depends on 7) The electronic key of claim 7, further comprising a ferromagnetic core of the key power coil disposed at least partially behind the first capacitive metal plate, wherein wire leads of the key power coil project through an aperture in the ferromagnetic core. ### Claim 12 (depends on 7) The electronic key of claim 7, wherein the key power coil is configured to inductively couple with a corresponding lock power coil of the lock assembly, wherein parasitic stray capacitance between the key power coil and the lock power coil provide a common reference for the first capacitive metal plate and the second capacitive metal plate. ### Claim 13 (depends on 2) The electronic key of claim 2, wherein the plate has a diameter greater than 5 mm. ### Claim 14 (depends on 13) The electronic key of claim 13, wherein the plate has a diameter between 6 mm and 9 mm. ### Claim 15 A method for communicating with an electronic lock, the method comprising: capacitively coupling a first metal plate of a key assembly with a second metal plate of a lock assembly; and transmitting data from the key assembly to the lock assembly by applying a data signal to the first metal plate. ### Claim 16 (depends on 15) The method of claim 15, further comprising inductively coupling a first power coil of a key assembly with a second power coil of a lock assembly; ### Claim 17 (depends on 16) The method of claim 16, wherein parasitic capacitance between the first power coil and the second power coil provides a common reference for the first metal plate and the second metal plate. ### Claim 18 (depends on 15) The method of claim 15, wherein coupling the first metal plate with the second metal plate comprises positioning the first metal plate in proximity to the second metal plate. ### Claim 19 (depends on 16) The method of claim 16, further comprising transmitting power using the first power coil simultaneously while transmitting the data. ### Claim 20 An electronic lock comprising: a housing; a locking mechanism disposed within the housing; a processor disposed within the housing; and a partial capacitor comprising a first capacitive metal plate in communication with the processor, the first capacitive metal plate configured to form a capacitor with a corresponding second capacitive metal plate of a key when brought into proximity with the second capacitive metal plate of the key; wherein the processor is programmed to process data signals received through the partial capacitor to actuate the locking mechanism. ### Claim 21 (depends on 20) The electronic lock of claim 20, wherein the first capacitive metal plate comprises an annulus. ### Claim 22 (depends on 21) The electronic lock of claim 21, wherein the annulus comprises a gap configured to inhibit electrical current in the annulus. ### Claim 23 (depends on 20) The electronic lock of claim 20, further comprising a dielectric cover covering at least a portion of the first capacitive metal plate. ### Claim 24 (depends on 21) The electronic lock of claim 21, further comprising a lock power coil. ### Claim 25 (depends on 24) The electronic lock of claim 24, wherein the lock power coil and the first capacitive metal plate are concentric. ### Claim 26 (depends on 21) The electronic lock of claim 21, further comprising a nose portion disposed within a hole formed by the annulus, wherein the lock power coil is disposed at least partially within the nose portion. ### Claim 27 (depends on 20) The electronic lock of claim 20, wherein the electronic lock is configured to simultaneously transfer data using the first capacitive metal plate and transfer power using the lock power coil.