Contactless identification device

• US 7,222,798 B2
• Filed: 06/01/2004
• Issued: 05/29/2007
• Est. Priority Date: 12/10/2001
• Status: Expired due to Term

• Current Assignee: Callahan Cellular LLC (Intellectual Ventures LLC)
• Original Assignee: Fractus SA
• Inventors: Ortigosa Vallejo, Juan Ignacio, Puente Ballarda, Carles
• Primary Examiner(s): ST CYR, DANIEL
• Application Number:
  US10/858,457
• Publication Number:
  US 20050161514A1
• Time in Patent Office: 1,092 Days
• Field of Search: 235/375, 235/487, 235/492, 235/494
• US Class Current: 235/492
• CPC Class Codes: G06K 19/045 the record carrier being of the non-contact type, e.g. RFID, and being specially adapted for attachment to a disc, e.g. a CD or DVD
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 5/40 Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

The invention relates to a contact-less identification device comprising a flat conducting structure as an electromagnetic sensor or transducer, and more particularly the invention relates to contactless cards, hybrid cards and radio operated electronic labels and tags. The electromagnetic sensor architecture according to the invention is suitable for all the applications where contactless or hybrid cards are of advantage: high volume paying and toll applications (public transportation, public sport events, person and good identification, access to controlled areas, control of shipment of goods, handling of luggage, product control in chain production environments), etc. The contact-less identification device according to the invention has had its performance enhanced by the use of space-filling techniques in the design of its electromagnetic sensor and by the use of a planar capacitor in conjunction with said flat conducting structure.

Claims

1. A contactless identification device comprising:

an integrated circuit;

a conducting wire or strip as an electromagnetic sensor; and

a capacitive element connected in parallel with said conducting wire or strip;

wherein the conducting wire or strip is a single-turn flat conducting wire and the capacitive element is a flat coplanar capacitor;

wherein the conducting wire or strip and the capacitive element are lying on a common single layer of the device;

wherein the capacitive element is surrounded by the conducting wire or strip;

wherein at least one of at least a portion of said conducting wire or strip and at least a portion of said capacitive element is shaped as a space-filling curve;

wherein the space-filling curve is defined as a curve composed by at least ten connected straight segments;

wherein said segments are smaller than a tenth of the operating free-space wave length and are spatially arranged so that none of said adjacent and connected segments form another longer straight segment.

2. The contactless identification device according to claim 1 wherein said segments intersect to each other at the tips of the curve.

3. The contactless identification device according to claims 1 or 2 wherein the corners formed by each pair of said adjacent segments are rounded or smoothed.

4. The contactless identification device according to claim 1 wherein the curve is periodic along a fixed straight direction of space if and only if the period is defined by a non-periodic curve composed by at least ten connected segments and no pair of said adjacent and connected segments define a straight longer segment.

5. The contactless identification device, according claim 1, wherein:

at least one of at least a part of said conducting wire or strip and at least a part of said capacitive element is shaped as a space-filling curve;

said space-filling curve features a box-counting dimension larger than one;

said box-counting dimension is computed as the slope of the straight portion of a log-log graph;

such a straight portion is substantially defined as a straight segment over at least an octave of scales on the horizontal axes of the log-log graph.

6. The contactless identification device according to claim 1, wherein at least one of at least a part of said conducting wire or strip and at least a part of said capacitive element is shaped either as a Hilbert or a Peano curve.

7. The contactless identification device according to claim 1 wherein at least one of at least a part of said conducting wire or strip and at least a part of said capacitive element is shaped as an SZ, ZZ, Hilbertzz, Peanoinc, Peanodec or Peanozz curve.

8. The contactless identification device according to claim 1, wherein said conducting wire or strip is shaped as a single-turn flat loop, in which at least a part of said loop is shaped as a space-filling curve.

9. The contactless identification device according to claim 1, wherein the conducting wire or strip forms a dipole electromagnetic sensor comprising two conducting arms in which at least a part of said conducting arms is shaped either as an space-filling curve, Hilbert, Peano, HilbertZZ, SZ, Peanoinc, Peanodec, PeanoZZ, or ZZ.

10. The contactless identification device, according to claim 1, wherein said capacitive element comprises two parallel conducting surfaces separated by a layer of insulating material and at least a part of said conducting surfaces is shaped as a space-filling curve.

11. The contactless identification device according to claim 1, wherein said capacitive element comprises two conducting coplanar surfaces separated by a gap between said coplanar metallic surfaces and at least a part of said gap or said conducting surfaces is shaped as a space-filling curve.

12. The contactless identification device according to claim 1, wherein at least one of the conductive wire or strip and the capacitive element is integrated in some of the inner layers of the identification device body.

13. The contactless identification device according to claim 1 wherein the conducting strip is a single-turn flat circular loop which includes radially-oriented space-filling structures.

14. The contactless identification device according to claim 1 wherein the conducting strip is a flat single-turn loop.

15. A method of manufacturing a contactless identification device, the method comprising:

forming a single-turn flat conducting strip and a flat coplanar capacitor element on a common single layer of a dielectric substrate so that the conducting strip and the capacitor element are connected in parallel;

wherein the coplanar capacitor element is surrounded by the conducting strip and

wherein at least one of the conducting strip and the capacitor element are formed following a space-filling curve.

16. The method according to claim 15 wherein the conducting strip and the capacitor are formed by printing conductive ink on a sheet-shaped substrate.

17. The method according to claim 15 wherein the conducting strip and the capacitor are formed by means of electrolytic etching part of a metal layer of a metal-dielectric sandwich sheet.

18. The method according to claim 15 wherein the conductive strip and the capacitor are integrated in one of the inner layers of a card body, an electronic label or radio frequency operated tag.

19. The method according to claim 15 wherein connecting terminals are formed in the connecting points between the conducting strip and the capacitor element, and a card chip is connected to said connecting terminals.