{"schema_version":"1.0","canonical_url":"https://patentable.app/patents/US-9754142","patent":{"patent_number":"US-9754142","title":"Method for detecting that contactless CPU card leaves radio-frequency field","assignee":null,"inventors":[],"filing_date":"2012-12-21T00:00:00.000Z","publication_date":"2017-09-05T00:00:00.000Z","cpc_codes":["G06K","G06K"],"num_claims":10,"abstract":"A method for detecting that a contactless CPU card leaves a radio-frequency field relates to the field of smart cards. The method comprises: receiving and judging whether a valid instruction sent by an upper computer is received, and conducting a corresponding operation according to the received instruction; as a notification card search instruction, conducting a card search operation, and judging whether returned information is received; obtaining card number information about a contactless card according to the returned information; as an APDU instruction, sending A data to the card in accordance with a designated format, judging whether a response is received, and sending the operation result to the upper computer; as an extension instruction, executing a corresponding operation, and sending the operation result to the upper computer; when a valid instruction is not received, judging the mark of the card in the radio-frequency field, and if the card is in the radio-frequency field, conducting a card detection operation, and sending the operation result to the upper computer; and if the card is not in the radio-frequency field, conducting a card search operation. The present invention can detect the problem that a CPU card leaves a radio-frequency field in real time."},"analysis":{"summary":null,"layman_explanation":null,"technical_analysis":null,"business_analysis":null,"faqs":null,"topics":[],"tech_cluster":null},"seo":{"title":"Method for detecting that contactless CPU card leaves radio-frequency field","description":"A method for detecting that a contactless CPU card leaves a radio-frequency field relates to the field of smart cards. The method comprises: receiving and judging whether a valid instruction sent by a","keywords":[]},"attribution":{"source":"Patentable","source_url":"https://patentable.app","canonical_url":"https://patentable.app/patents/US-9754142","license":"CC-BY-4.0-like","license_terms":"AI-generated analysis on this page (summary, layman_explanation, technical_analysis, business_analysis, faqs) may be reused with attribution and a visible link back to the canonical URL above. Patent abstracts, claims, and bibliographic data are USPTO public domain.","required_link":"https://patentable.app/patents/US-9754142","citation_suggestion":"Patentable. \"Method for detecting that contactless CPU card leaves radio-frequency field\" (US-9754142). https://patentable.app/patents/US-9754142","copyright_holder":"Nomic Interactive Technology LLC"},"links":{"html":"https://patentable.app/patents/US-9754142","json":"https://patentable.app/api/llm-context/US-9754142","site":"https://patentable.app","llms_txt":"https://patentable.app/llms.txt"},"generated_at":"2026-06-06T06:36:23.000Z"}