RF tagging system with multiple decoding modalities

• US 5,604,486 A
• Filed: 05/27/1993
• Issued: 02/18/1997
• Est. Priority Date: 05/27/1993
• Status: Expired due to Fees

• Current Assignee: HID Corporation (Assa Abloy AB)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lauro, George L., Istvan, Rudyard L., Ghaem, Sanjar
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): WONG, ALBERT KANG
• Application Number:
  US08/067,923
• Time in Patent Office: 1,363 Days
• Field of Search: 340/572, 340/825.54, 340/505, 340/825.3, 340/825.44, 340/539, 235/383, 235/385, 342/42, 342/51
• US Class Current: 340/10.3
• CPC Class Codes: G08B 13/2414 using inductive tags
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2448 Tag with at least dual detection means, e.g. combined inductive and ferromagnetic tags, dual frequencies within a single technology, tampering detection or signalling means on the tag
• CPC Class Codes: G08B 13/2471 Antenna signal processing by receiver or emitter
• CPC Class Codes: G08B 13/2482 EAS methods, e.g. description of flow chart of the detection procedure

Abstract

An RF tagging system includes an RF tag (10, 30) and an RF tag reader 80. The RF tag includes a plurality of RF resonant circuits. Each RF resonant circuit is resonant at a given RF frequency. A group of decoder RF resonant circuits (12, 32) have resonant frequencies defining one of a plurality of predetermined decoding modalities. A group of data RF resonant circuits (14, 34) have resonant frequencies corresponding to a predetermined identification code when the resonant frequencies of the data RF resonant circuits are decoded in accordance with the one decoding modality. The RF tag reader detects the resonant frequencies of the decoder RF resonant circuits and determines the one decoding modality. The RF tag reader is operative in each of the plurality of predetermined decoding modalities, detects the resonant frequencies of the group of data RF resonant circuits, and decodes the resonant frequencies of the group of data RF resonant circuits in accordance with the one decoding modality to provide the identification code. The decoder RF resonant circuits may also indicate the number of data RF resonant circuits on the RF tag. The RF tag reader determines the predetermined number from the decoder RF resonant circuits to confirm the accurate detection of the data RF resonant circuits. The RF tag reader, when selecting a decoding modality in accordance with the detected resonant frequencies of the decoder RF resonant circuits, determines various frequency bands and alters the RF tag reader frequency detection operation for accurate detection of the data RF resonant circuits.

Claims

1. An RF tagging system comprising:

an RF tag including a plurality of RF resonant circuits, each said RF resonant circuits being resonant at a given RF frequency, said plurality of RF resonant circuits including a predetermined number of data RF resonant circuits having resonant frequencies, in various frequency bands, corresponding to a predetermined identification code and a group of decoder RF resonant circuits having resonant frequencies indicative of said various frequency bands; and

an RF tag reader for detecting the resonant frequencies of said data RF resonant circuits to provide said identification code and for detecting the resonant frequencies of said decoder RF resonant circuits and determining said various frequency bands, and altering reader frequency detection operation in accordance with the determined frequency bands, in accordance with said detected decoder resonant frequencies for accurate detection of all said data RF resonant circuits.