Rfid-label with an element for regulating the resonance frequency

• US 6,796,508 B2
• Filed: 02/19/2003
• Issued: 09/28/2004
• Est. Priority Date: 03/28/2000
• Status: Expired due to Fees

• Current Assignee: Lucatron AG
• Original Assignee: Lucatron AG
• Inventors: Müller, Philipp
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): LE, UYEN CHAU N
• Application Number:
  US10/239,793
• Publication Number:
  US 20030169153A1
• Time in Patent Office: 587 Days
• Field of Search: 235/492, 235/441, 235/451, 235/462.13
• US Class Current: 235/492
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• 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: G08B 13/2414 using inductive tags
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2431 Tag circuit details

Abstract

An RFID label comprises a resonant circuit consisting of a coil and a capacitor. The RFID label is provided with an additional element (13, 17, 20, 21) for regulating the resonance frequency of the resonant circuit. The additional element is applied to the surface of the RFID label after production of the same. The additional element can be especially a sticker with a conductive layer, which is stuck in such a way that it partially overlaps individual conductive surfaces of the label to produce an additional capacitance, or which is simply stuck into the coil to reduce the effective inductance of the coil. Alternatively, the element can be formed by a layer with a high relative permittivity which is applied between two conductive surfaces.

Claims

1. RFID label for identification of an article comprising a substrate made of a plastic film and conductive surfaces on the front and the back side of the substrate, the conductive surfaces forming, a plurality of electrical components including an electrical resonant circuit which comprises a coil with at least one coil winding and a capacitor with a first capacitor plate on the front side of the substrate and a second capacitor plate on the back side of the substrate with a first conductive surface being arranged on the front side of the substrate conductively connected with the second plate of the capacitor on the back side of the substrate, wherein the RFID label further comprises an integrated semiconductor circuit in the form of a miniature chip, electrical terminals of which being connected, on one side, to the first conductive surface and, on another side, to a conductive surface that is essentially at the same electrical potential as the first plate of the capacitor, thereby the miniature chip being driven by a voltage of the capacitor, and an additional element other than the article subsequently applied to a surface of the RFID label which changes the a resonant frequency of the resonant circuit.

2. The RFID label according to claim 1, wherein the additional element includes a sticker with a metallic conductive layer.

3. The RFID label according to claim 2, characterized in that the sticker is applied to at least partly overlap at least two conductive surfaces arranged next to each other on the same side of the substrate, for increasing an effective capacitance of the resonant circuit.

4. The RFID label according to one of claim 2 or 3, characterized in that the sticker is arranged to at least partly overlap the first conductive surface as well as one conductive surface which is essentially at the same electrical potential as the first plate of the capacitor, for increasing an effective capacitance of the resonant circuit.

5. The RFID label according to claim 3, characterized in that the sticker is applied to the same side of the substrate as the conductive surfaces with which the sticker acts jointly with an adhesive insulating layer directly on these conductive surfaces.

6. The REID label according to any one of claims 2 and 3, characterized in that the sticker is applied at least partly in an area inside the coil for reducing an effective inductance of the resonant circuit.

7. The RFID label according to claim 6, characterized in that the area inside the coil (4) has a center and that the sticker is applied away from this center.

8. The RFID label according to any one of claims 1-3, further comprising a local layer of a material having a high dielectric constant, the local layer bridging a gap between two conductive surfaces of a different electrical potential on the same side of the substrate.

9. The REID label according to claim 8, characterized in that the material can be applied in a liquid or paste state and subsequently solidifies and/or dries and/or hardens.

10. The REID label according to claim 8, characterized in that the local layer bridges a gap between the first conductive surface as well as a conductive surface that is essentially at the same electrical potential as the first plate of the capacitor.

11. The RFID label according of claim 8, wherein the dielectric constant is in the range between ε

_r 2 and 10.

12. The REID label according to claim 3, characterized in that the sticker is applied to the opposite side of the substrate to the conductive surfaces with which the sticker acts jointly.

13. The RFID label according to claim 3, characterized in that the sticker is conductively connected to a conductive surface on one side of the substrate and the sticker is also arranged at least partly overlapping another conductive surface of a different potential on the opposite side of the substrate.

14. The RFID label according to claim 2, wherein the sticker is made of aluminum.

15. The REID label according to claim 1, wherein the additional element is applied to one of the conductive surfaces on the front or back side of the substrate.

16. The REID label according to claim 1, wherein the additional element is applied on a free surface inside the coil and the additional element does not overlap with any of the conductive surfaces.

17. The RFID label according claim 1, wherein a size of the additional element is smaller than a size of the RFID label.

18. The REID label for identification of an article comprising:

a substrate made of a plastic film; and

conductive surfaces on the front and the back side of the substrate,

wherein the conductive surfaces form a plurality of electrical components including;

an electrical resonant circuit which comprises a coil with at least one coil winding;

a capacitor with a first capacitor plate on the front side of the substrate and a second capacitor plate on the back side of the substrate;

a first conductive surface being arranged on the front side of the substrate conductively connected with the second plate of the capacitor on the back side of the substrate; and

a sticker subsequently applied to one of the conductive surfaces on the front or back side of the substrate which changes a resonant frequency of the resonant circuit, characterized in that the sticker is applied to the opposite side of the substrate to the conductive surfaces with which the sticker acts jointly.

19. The REID label for identification of an article comprising:

a substrate made of a plastic film; and

conductive surfaces on the front and the back side of the substrate,

wherein the conductive surfaces form a plurality of electrical components including;

an electrical resonant circuit which comprises a coil with at least one coil winding;

a capacitor with a first capacitor plate on the front side of the substrate and a second capacitor plate on the back side of the substrate;

a first conductive surface being arranged on the front side of the substrate conductively connected with the second plate of the capacitor on the back side of the substrate; and

a sticker subsequently applied to one of the conductive surfaces on the front or back side of the substrate which changes a resonant frequency of the resonant circuit,

characterized in that the sticker is conductively connected to a conductive surface on one side of the substrate and the sticker is also arranged at least partly overlapping another conductive surface of a different potential on the opposite side of the substrate.