# US 2019/0379243 A1 · Method for detecting foreign material, and device and system therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0379243 A1 - Document ID: US20190379243A1 - Status: Published application - Kind: A1 - Application number: 16/539,511 - Filed: 2019-08-13 - Published: 2019-12-12 - Earliest claimed: 2016-07-01 - Assignees: LG Innotek Co., Ltd. - Applicants: LG Innotek Co., Ltd. - Inventors: Jae Hee PARK; Yong Il KWON - Web page: https://patentgrep.com/patent/US20190379243A1 ## CPC - H02J 50/60: responsive to the presence of foreign objects, e.g. detection of living beings - G01N 27/02: by investigating impedance - G01R 27/26: Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants {; Measuring impedance or related variables} - H02J 3/02: using a single network for simultaneous distribution of AC power at different frequencies - H02J 7/02: for charging batteries from AC mains by converters - H02J 7/64: against overvoltage - H02J 13/10: characterised by displaying of information or by user interaction, e.g. supervisory control and data acquisition [SCADA] systems - H02J 50/12: of the resonant type - H02J 7/47: Arrangements for checking compatibility or authentication between one component, e.g. a battery or a battery charger, and another component, e.g. a power source - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A method for detecting a foreign object disposed in a charging area of a wireless power transmitter can include transmitting, by the wireless power transmitter, a power signal having a predetermined strength; measuring, via a controller, a peak frequency of the power signal; receiving, from a wireless power receiver, information about a reference peak frequency of the wireless power receiver; determining, via the controller, a threshold frequency based on the reference peak frequency; and determining, via the controller, whether the foreign object is present in the charging area based on a comparison of the measured peak frequency of the power signal with the determined threshold frequency. ## Claims ### Claim 1 A method for detecting a foreign object disposed in a charging area of a wireless power transmitter, the method comprising: transmitting, by the wireless power transmitter, a power signal having a predetermined strength; measuring, via a controller, a peak frequency of the power signal; receiving, from a wireless power receiver, information about a reference peak frequency of the wireless power receiver; determining, via the controller, a threshold frequency based on the reference peak frequency; and determining, via the controller, whether the foreign object is present in the charging area based on a comparison of the measured peak frequency of the power signal with the determined threshold frequency. ### Claim 2 (depends on 1) The method according to claim 1, wherein the peak frequency of the power signal is shifted when the foreign object is present in the charging area. ### Claim 3 (depends on 1) The method according to claim 1, wherein the information includes a foreign object detection status packet comprising a reference peak frequency value of the reference peak frequency of the wireless power receiver. ### Claim 4 (depends on 3) The method according to claim 3, wherein the reference peak frequency is measured with the wireless power receiver turned off. ### Claim 5 (depends on 1) The method according to claim 1, wherein the threshold frequency is determined based on a preset tolerance in addition to the reference peak frequency. ### Claim 6 (depends on 1) The method according to claim 1, wherein the reference peak frequency includes a frequency corresponding to a Q-factor in an operating frequency range of the wireless power transmitter. ### Claim 7 (depends on 1) The method according to claim 1, further comprising: transmitting, by the wireless power transmitter, a response indicating the foreign object is present in the charging area when the measured peak frequency of the power signal is greater than the threshold frequency; and transmitting, by the wireless power transmitter, the response indicating the foreign object is not present in the charging area when the measured peak frequency of the power signal is equal or less than the threshold frequency. ### Claim 8 (depends on 7) The method according to claim 7, further comprising: suspending the power signal if the controller of the wireless power transmitter determines the foreign object is present in the charging. ### Claim 9 A wireless power transmitter for detecting a foreign object disposed in a charging area of the wireless power transmitter, the wireless power transmitter comprising: a transmitting unit configured to transmit a power signal having a predetermined strength; and a controller configured to: measure a peak frequency of the power signal, receive, from a wireless power receiver, information about a reference peak frequency of the wireless power receiver, determine a threshold frequency based on the reference peak frequency, and determine whether the foreign object is present in the charging area based on a comparison of the measured peak frequency of the power signal with the determined threshold frequency. ### Claim 10 (depends on 9) The wireless power transmitter according to claim 9, wherein the peak frequency of the power signal is shifted when the foreign object is present in the charging area. ### Claim 11 (depends on 9) The wireless power transmitter according to claim 9, wherein the information includes a foreign object detection status packet. including a reference peak frequency value of the reference peak frequency of the wireless power receiver. ### Claim 12 (depends on 9) The wireless power transmitter according to claim 9, wherein the reference peak frequency includes a frequency corresponding to a Q-factor in an operating frequency range of the wireless power transmitter. ### Claim 13 (depends on 9) The wireless power transmitter according to claim 9, wherein the controller is further configured to: transmit a response indicating the foreign object is present in the charging area when the measured peak frequency of the power signal is greater than the threshold frequency, and transmit the response indicating the foreign object is not present in the charging area when the measured peak frequency of the power signal is equal or less than the threshold frequency. ### Claim 14 (depends on 9) The wireless power transmitter according to claim 9, wherein the controller is further configured to: suspend the power signal if the controller determines the foreign object is present in the charging area. ### Claim 15 A method for detecting a foreign object disposed in a charging area of a wireless power transmitter, the method comprising: transmitting, by a wireless power receiver to the wireless power transmitter, a foreign object detection status packet including information about a reference peak frequency of the wireless power receiver; and receiving, by the wireless power receiver from the wireless power transmitter, a response indicating the foreign object is present or not present in the charging area, wherein the response is determined based on the reference peak frequency of the wireless power receiver. ### Claim 16 (depends on 15) The method according to claim 15, wherein the response indicates the foreign object is present in the charging area when a measured peak frequency of a power signal transmitted by the wireless power transmitter is greater than a threshold frequency. ### Claim 17 (depends on 15) The method according to claim 15, wherein the response indicates the foreign object is not present in the charging area when a measured peak frequency of a power signal transmitted by the wireless power transmitter is equal to or less than the threshold frequency. ### Claim 18 (depends on 16) The method according to claim 16, wherein the peak frequency of the power signal is shifted from the reference peak frequency when the foreign object is present in the charging area. ### Claim 19 (depends on 15) The method according to claim 15, wherein the reference peak frequency includes a frequency corresponding to a Q-factor in an operating frequency range of the wireless power transmitter. ### Claim 20 (depends on 15) The method according to claim 15, further comprising: suspend receiving a wireless power transmitted from the wireless power transmitter if the response indicating the foreign object is not present in the charging area is received.