Registers – Records – Conductive
Reexamination Certificate
1999-05-26
2003-09-23
Frech, Karl D. (Department: 2876)
Registers
Records
Conductive
C235S487000
Reexamination Certificate
active
06622921
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an identification element having an integrated circuit and an antenna coil connected to the integrated circuit(RFID transponder)
BACKGROUND OF THE INVENTION
The advantage of RFID transponders compared to the bar-codes predominantly used in particular in the goods marking sector is that they permit a direct exchange of information, meaning that no visual contact is needed between the interrogating device and the transponder for the information transfer. Unlike bar-codes, furthermore, it is an easy matter with RFID transponders to change their information content directly as and when required.
It will be understood, of course, that RFID transponders may find application in the most diverse areas, particularly in the fields of production, further processing and handling of goods as well as in the security sector. Examples include the identification marking of people and animals, the identification marking of baggage and packages, particularly at airports and post offices, and the identification marking of vehicles during their production or in multistory car parking garages.
The disadvantage of the known RFID transponders compared to bar-codes is the immense difference in price between the two elements. This is also the reason why the use of RFID transponders in the sales sector has been restricted so far to fringe areas. In particular there has been no interest to date in using RFID transponders to present price information or other data when selling mass products in department stores and warehouses, considering that an RFID transponder costs in the region of DM 10. This naturally makes their use as disposable identification markers completely out of the question.
RFID transponders are constructed as either passive or active elements. If the RFID transponder is used as an active element, the housing enclosing the integrated circuit contains an additional energy source usually in the form of a battery. RFID transponders are able to operate in the most diverse frequency ranges, for example, in the low frequency range at 125 kHz, in the medium frequency range at 13.56 MHz, or in the microwave range at typically 2.45 GHz. The present invention relates preferably—but by no means exclusively—to passive transponders operating in the medium frequency range.
A data carrier with an integrated circuit is known in the art from European Patent EP 0 682 321 A2. The data carrier disclosed there is comprised of a card body and an integrated circuit connected electrically via contact elements to at least one coil composed of one or several layers. The elements combine to form a resonant circuit which operates at a predetermined resonant frequency. The purpose of the coil is to supply energy and/or to exchange the data of the integrated circuit with external devices. Circuit and contact elements are each constructed as a separate module.
The manufacturing cost of this known configuration of a transponder is so high that it is only suitable for use on up-market products. It is completely unsuited for use on mass products.
A method of bonding an integrated circuit to a resonant circuit mounted on a flexible substrate and a corresponding transponder is described in European Patent EP 0 821 406 A1. The resonant circuit disclosed is formed of two electrically conductive patterns arranged on either side of the flexible substrate. The resonant circuit has a certain inductance and a certain capacitance. To ensure a reliable bond between the integrated circuit and the resonant circuit, the bonding area on the flexible substrate is cleaned. Then the integrated circuit is connected to the resonant circuit by a technique referred to as wire bonding which is known from semiconductor technology. To prevent the bond from being destroyed by external impact, a protective coating is applied to the integrated circuit and the bonding area.
A disadvantage of this known method and known transponder is the relatively high cost for the individual parts and for the manufacture, considering that it is absolutely necessary, following bonding the integrated circuit to the resonant circuit, to apply a protective coating to the circuit and the bonding area. Typically, transponders are integrated into labels. Because in the area of the chip the transponder is substantially thicker than in the remaining areas, this presents major printing problems using, for example, a thermal printer for printing labels. Moreover, the conducting patterns forming the resonant circuit are applied to the substrate by etching. Etching is a relatively expensive process which, in addition, poses a severe environmental pollution problem.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an economically priced and reliably operating identification element.
This object is accomplished in that the antenna coil is comprised of a lower conducting track and an upper conducting track, that each track includes a plurality of turns, that the two tracks are arranged on either side of a dielectric layer, and that the relative position of the two tracks is such that they overlap substantially only in one or in two selected areas.
The advantages of the present invention reside in that the inductance of the antenna coil is relatively high as a result of the high number of turns of the two tracks. In particular, the inductance can be dimensioned such that, with a predetermined interrogation field in a predetermined space, the output voltage is sufficient to activate, that is, operate the integrated circuit. Furthermore, the feature involving overlapping of the two tracks essentially only at their inner and/or outer ends produces the effect that these areas make the major contribution to the capacitance of the antenna coil, while the contributions made by the remaining areas of track overlap (that is, the areas in which the tracks intersect) are vanishingly small. This makes it possible to obtain a higher inductance and hence again a higher induced voltage for operating the integrated circuit at the predetermined excitation frequency of the antenna coil.
In an advantageous aspect of the present invention, provision is made for the two antenna coils to be electrically interconnected in one of the two areas of track overlap, preferably in the outer area of track overlap.
In an advantageous further feature of the identification element of the present invention, provision is made for the integrated circuit to be a non-encapsulated chip. Obviously, this presents an extremely economical solution. In cases where the identification element is integrated into a label, printing as by a thermal printer is in addition substantially facilitated because a non-encapsulated transponder is substantially thinner than an encapsulated transponder.
Preferably, the conducting tracks are parts which are die-stamped from a metal foil material. A very low-cost method of manufacturing resonant labels is known in the art from European Patent EP 0 655 705 A1. The manufacturing method disclosed in this patent can be employed in the manufacture of the antenna coil.
According to an advantageous aspect of the solution of the present invention, it is proposed using a dielectric adhesive for the dielectric layer. This aspect is equally described in the European Publication referred to above.
The operating voltage of the integrated circuit, meaning the non-encapsulated chip, is of the order of 2 volts. In an advantageous aspect of the identification element of the present invention, provision is made for the number of turns of the tracks, which number is proportional to the inductance of the antenna coil and hence to the induced voltage, and for the size of the area of track overlap to be selected such that the output voltage of the antenna coil is in the voltage range with the predetermined interrogation field in a predetermined space.
To compensate for manufacturing tolerances, an advantageous embodiment of the identification element of the present invention provides for the antenna coil, following manufacture, to be tunab
Altwasser Richard
Robson David
Franklin Jamara A
Frech Karl D.
Jones Tullar & Cooper P.C.
Meto International GmbH
LandOfFree
Identification element does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Identification element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Identification element will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3107221