A passive RFID circuit (transponder) generally consists of a tuned circuit, which often takes the form of a external antenna which receives both power and an information signal from the electromagnetic field emanated by a second system component (RFID reader), and a integrated circuit, which contains the microprocessor and memory components by which the transponder decodes and respond to an interrogation signal.
The design of the tuned circuit, herein referred to as the “antenna”, can be carefully designed in order to facilitate satisfactory response to the field emanated by the RFID reader. Configuring the antenna such that disruption of the antenna by breaking one of the conductive traces of the antenna may be used to produce a tamper evident RFID device. Such RFID circuits can be used for wristbands and security locking devices, such as package security. The proper configuration and stability of passive components of the antenna (such as resistors and capacitors) can be required to maintain suitable performance of the antenna. A security device may be configured such that tampering with these passive components will cause either impaired or wholly different function of the device. Thus it is possible to configure a tamper evident RFID whose function is altered by configuring the passive components of the antenna. Further the device may be configured such that tampering with the components will likely disrupt several components simultaneously thus rendering the tamper evident nature of the device more robust than one in which tampering disrupts only one component.
In the RFID circuit 100 of
An RFID wristband with a robust tamper evident closure may be formed by the insertion of the strap 108 of the wristband through the hole 106a and effecting the fastening of the wristband by folding the circuit along line l. Any attempt to cut the wristband is likely to sever the circuit that extends through the band if the band is cut in any position. Any attempt separate the adhesively joined sections is likely to disrupt the tuning of the circuit, such as by damaging the capacitors, and render the antenna non-functional. The antenna portion and/or capacitor(s) can be made of a conductive ink material that is susceptible to damage.
The substrate can have printed indicia, such as the line l, along a centerline of the fold section. A strap 108 can fit through the center hole 106a. The RFID antenna portion 104 can extend through the strap portion 108. A connection region can be used to connect the antenna portion 104 to an RFID IC 110. When the strap 108 is adhered to the wristband the RFID antenna portion 104 can extend completely around the wristband such that the wristband cannot be cut off without modifying the RF response of the RFID circuit.
One embodiment of the present invention is an RFID wristband comprising a substrate 102, an antenna portion 104 on the substrate 102; a strap 108 on the substrate 102; and a fold section 106 on the substrate 102. The fold section 106 can contain an adhesive layer (shaded region) and wherein when the fold section 100 is folded together with the adhesive layer at least one capacitor is created which set the RF response of the RFID circuit. The fold section can have hole 106a that the strap 108 fits into such that adhesive layer of the fold section 106 can hold the strap 108 in place. When the strap 108 is held in place with the adhesive. The strap 108 can be positioned apart from any capacitor.
The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to one of the ordinary skill in the relevant arts. The embodiments were chosen and described in order to best explain the principles of the invention and its partial application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention is defined by the claims and their equivalents.
Number | Name | Date | Kind |
---|---|---|---|
3759246 | Flack et al. | Sep 1973 | A |
5058161 | Weiss | Oct 1991 | A |
5463377 | Kronberg | Oct 1995 | A |
5598032 | Fidalgo | Jan 1997 | A |
5629981 | Nerlikar | May 1997 | A |
5874902 | Heinrich et al. | Feb 1999 | A |
5892611 | Iisuka | Apr 1999 | A |
5942978 | Shafer | Aug 1999 | A |
5963134 | Bowers et al. | Oct 1999 | A |
6049461 | Haghiri-Tehrani et al. | Apr 2000 | A |
6089284 | Kaehler et al. | Jul 2000 | A |
6107920 | Eberhardt et al. | Aug 2000 | A |
6111520 | Allen et al. | Aug 2000 | A |
6130623 | MacLellan et al. | Oct 2000 | A |
6133833 | Sidlauskas et al. | Oct 2000 | A |
6144303 | Federman | Nov 2000 | A |
6147605 | Vega et al. | Nov 2000 | A |
6181287 | Beigel | Jan 2001 | B1 |
6204760 | Brunius | Mar 2001 | B1 |
6384727 | Diprizio et al. | May 2002 | B1 |
6400323 | Yasukawa et al. | Jun 2002 | B2 |
6421013 | Chung | Jul 2002 | B1 |
6514790 | Plettner et al. | Feb 2003 | B1 |
6774800 | Friedman et al. | Aug 2004 | B2 |
6849936 | Berman et al. | Feb 2005 | B1 |
7168626 | Lerch et al. | Jan 2007 | B2 |
7283054 | Girvin et al. | Oct 2007 | B2 |
20020140608 | Zaghloul et al. | Oct 2002 | A1 |
20030116790 | Kikuchi et al. | Jun 2003 | A1 |
20030173408 | Mosher et al. | Sep 2003 | A1 |
20040066296 | Atherton | Apr 2004 | A1 |
20040070510 | Zhang et al. | Apr 2004 | A1 |
20040104274 | Kotik et al. | Jun 2004 | A1 |
20040189470 | Girvin et al. | Sep 2004 | A1 |
20060087437 | Lerch et al. | Apr 2006 | A1 |
Number | Date | Country |
---|---|---|
0 903 805 | Mar 1999 | EP |
Number | Date | Country | |
---|---|---|---|
20070125867 A1 | Jun 2007 | US |