Resonant tag

• US 5,119,070 A
• Filed: 10/15/1991
• Issued: 06/02/1992
• Est. Priority Date: 01/25/1989
• Status: Expired due to Term

• Current Assignee: Checkpoint Manufacturing Japan Co., Ltd. (CCL Industries Incorporated)
• Original Assignee: Tokai Metals Company Limited
• Inventors: Suzuki, Yuji, Matsumoto, Takeshi
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US07/774,158
• Time in Patent Office: 231 Days
• Field of Search: 340/572, 361/397, 361/410
• US Class Current: 340/572.5
• CPC Class Codes: B32B 2519/02 RFID tags
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/242 Tag deactivation
• CPC Class Codes: G08B 13/2437 Tag layered structure, processes for making layered tags
• CPC Class Codes: G08B 13/244 Tag manufacturing, e.g. continuous manufacturing processes
• CPC Class Codes: G08B 13/2442 Tag materials and material properties thereof, e.g. magnetic material details
• CPC Class Codes: H01L 27/01 comprising only passive thin-film or thick-film elements formed on a common insulating substrate passive two-terminal components without a potential-jump or surface barrier for integrated circuits, details thereof and multistep manufacturing processes therefor H01L28/00
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor
• CPC Class Codes: H05K 3/4084 by deforming at least one of the conductive layers

Abstract

A resonant tag carries a plurality of resonant circuits having different resonant frequencies. The resonant circuit is composed of a first conductive pattern formed by a conductive metal foil on one surface of an insulating thin film and a second conductive pattern formed by a conductive metal foil on the other surface of the insulating thin film. The first conductive pattern contains an inductor element and an element of the capacitor, which correspond to a resonant frequency of the resonant circuit. The second conductive pattern contains the other element of the capacitor element. The capacitor element of the second conductive pattern, which corresponds to the resonant frequency, is disposed at a position where it faces the capacitor element of the first conductive pattern formed on one surface of the insulating thin film. When the resonant tag is used, the conductive metal foils formed on the two surfaces of the insulating synthetic resin film are electrically connected so as to turn off part of the resonant circuits, so that the resonant tag can be identified by a combination of resonant frequencies inherent in the remaining resonant circuits. For example, n (two or more) resonant circuits having different resonant frequencies may be formed on a resonant tag so that the tag can be identified in 2ⁿ -1 (or 2ⁿ) different ways.

Claims

1. A resonant tag having an insulating substrate with opposite surfaces and a plurality of resonant circuits, each resonant circuit comprising:

an inductor element pattern formed on one of said opposite surfaces of said substrate, having an inductor terminal portion centrally located on said one surface and said inductor element pattern extending spirally from the inductor terminal portion and ending in a first triangular portion at one corner of the resonant circuit,

a capacitor element pattern formed on the other opposite surface of said substrate, having a capacitor terminal portion centrally located and in alignment with the inductor terminal portion on the opposite surface of the substrate, said capacitor element pattern extending from the capacitor terminal portion to a second triangular portion at one corner of the resonant circuit, said first and second triangular portions being in alignment with each other on opposite sides of the substrate, each of said inductor element pattern and said capacitor element pattern being oriented so as to provide the resonant circuit with a central area essentially free of conductive elements,

means for selectively electrically connecting the centrally located inductor and capacitor terminal portions of the inductor and capacitor element patterns of each resonant circuit to form an LC resonant circuit having an independent inherent resonant frequency in accordance with said inductor and capacitor element patterns, and

an electrically independent conductive pattern forming a separating pattern around each resonant circuit to shield the resonant circuit frequency from the electromagnetic effects of each of the other resonant circuit frequencies.

2. A resonant tag according to claim 1, wherein the plurality of resonant circuits are formed in a plurality of rows, wherein said capacitor element patterns of one of said rows are oriented in a first direction and said capacitor element patterns of at least two other of said rows are oriented in a second direction, said second direction being different from said first direction.