Tags or labels useful in connection with an electronic article surveillance system

Description

[0001] The invention relates to a device for interacting with an electronic article surveillance system and to a device for use in a system for providing a facility with articles to which devices have been attached according to the preambles of independent claims 1 and 8, respectively.

[0002] The so-called "electronic article surveillance" involves the use of electronically detectable tags or labels which are attached to articles of merchandise in order to protect these articles from unauthorized removal, such as by shoplifting.

[0003] For enhanced security and inventory control, the use of electronic article surveillance (EAS) systems has become increasingly widespread. These systems utilize tags or labels which contain an electronic circuit (e.g., a resonant circuit) for interacting with an applied (e.g., swept radio-frequency) electromagnetic field. A transmitter and accompanying antenna produce this field, and a nearby receiver and accompanying antenna detect variations in the received field caused by the presence of a tag. This transmitting and receiving equipment is positioned at the location or locations where it is desired to detect the unauthorized removal of tag-bearing articles, e.g., at the exit of a retail store.

[0004] The tags attached to those articles whose removal is authorized (e.g., because these articles have been properly checked out) are either physically removed from the articles, or deactivated, i.e. treated so that they become incapable of producing detectable variations in the received field. Otherwise, these tags will be detected and an alarm signal will be produced by the equipment. Commercial EAS systems as generally described above are available from manufacturers such as Checkpoint Systems, Inc. of Thorofare, New Jersey, among others.

[0005] An important consideration in the use of such EAS systems is the manner in which the detectable tags or labels are applied to the articles which are to be protected. Some retail stores, for example, wish to have tags applied to all the articles in their inventory, while others wish to have tags applied only to some of these articles, leaving others untagged. Likewise the selection of the kinds of merchandise to be tagged may vary from store to store, and from time to time within the same store. Even within a common "family" of stores, such as the member stores of a chain, these practices may--and frequently do--vary from one store to another. This variety, coupled with the absence until now of any practical technique for avoiding local tag application, has led to the common practice for users of EAS systems to tag articles locally, at each EAS equipped store.

[0006] However, such "store" tagging is time consuming and labor intensive. Also, store tagging is often delegated to personnel who may be limited in training or interest. This can compromise the effectiveness of EAS, which is obviously significantly dependent upon proper tagging of the articles to be protected.

[0007] In view of all this, theoretical consideration has previously been given to the possibility of performing the desired tagging of articles at some other point, upstream from the store itself in the distribution chain, such as at the merchandise manufacturing stage, or at some intermediate stage of warehousing or distribution. This theoretical possibility has not found practical realization because of certain formidable obstacles.

[0008] If detectable tags were to be applied to articles of merchandise at their manufacturing stage, then a given product line would have to be processed in two different varieties, one tagged and one not tagged. Moreover, this segregation would have to be perpetuated throughout the subsequent distribution channels. The reason for this is that many--indeed most--stores do not yet use EAS. These non-EAS using stores would need to be reliably supplied with non-tagged articles; otherwise EAS tags would leave these stores, still attached to the articles being sold, and thereby create what is sometimes called "pollution" of the marketplace with EAS tags. Conversely, stores which do use EAS would have to be reliably supplied with tagged articles, or their EAS protection would become ineffective.

[0009] If, on the other hand, EAS tags were to be applied at an intermediate distribution stage, this would require breaking the bulk packaging which is typically used at those stages, handling the individual articles, and repackaging them in bulk. Furthermore, subsequent segregation of tagged and not-tagged articles would again be required.

[0010] US-A-4 021 705 discloses a device for interacting with an electronic article surveillance system wherein said device comprises a resonant circuit responsive to an applied radio-frequency field, and includes means for interacting with said electronic article surveillance system in a first mode of operation (fuse 23 destructed, fuse 32 intact) in which said resonant circuit is configured to resonate at a first frequency (detection frequency) corresponding to an operative frequency of said electronic article surveillance system, and in a second mode of operation (fuses 23 and 32 intact) in which said resonant circuit is configured to resonate at a second frequency (enabling frequency) different from the operative frequency of said electronic article surveillance system, said interacting means being capable of interacting with said electronic article surveillance system for activation thereof, said' interacting means including means for modification from said second mode of operation to said first mode of operation (application of energizing field in order to destruct fuse 23), said modification means being operative at said second frequency (enabling frequency). All embodiments disclosed in US-A-4 021 705 include circuits having simultaneous double resonances.

[0011] The present invention is suitable for a technique for protecting articles by means of EAS, without having to apply the necessary detectable tags or labels to these articles at the actual EAS-using stores.

[0012] The present invention is also suitable for a tagging technique which no longer requires a store to individually tag articles which are to be protected by EAS.

[0013] The present invention is also suitable for a tagging technique which can be performed without having to break the bulk packaging of the articles to be protected by EAS.

[0014] The present invention is also suitable for a tagging technique which can be performed without having to break bulk packaging, while still enabling individual stores to adhere to their individual practices with regard to which articles are to bear EAS detectable tags.

[0015] The present invention is also suitable for an EAS tagging technique which makes it unnecessary to create two segregated varieties of the same articles, one tagged and one not tagged, upstream from the stores in which these articles are to be retailed.

[0016] It is the primary object of the present invention to provide EAS tags or labels which are particularly suitable for the achievement of the above-stated objects.

[0017] This object is achieved in accordance with the present invention by a device comprising the features of the characterizing parts of independent claims 1 and 8, respectively.

[0018] The device according to the present invention is used for tagging the articles in question, not at the individual EAS equipped stores, as heretofore, but upstream in the distribution chain, preferably in conjunction with their manufacture. This upstream tagging is performed by means of tags which, at that stage, are not yet detectable by the EAS equipment with which they are ultimately destined to function. Furthermore, these tags remain undetectable through the subsequent distribution channel, until they reach that stage at which it is inherently determined that all the so-tagged articles in a given bulk package will be used in an EAS equipped store. This will typically occur at the merchandise receiving facility of such an individual store. At that stage, the tags previously attached to the individual articles are rendered detectable and the articles with the now-detectable tags attached, are then processed through the store in conventional manner.

[0019] By proceeding in accordance with the above described technique, the time and labor required for store tagging is eliminated and the reliability of the tagging procedure greatly enhanced. Moreover, it becomes practical to tag articles in ways which are less visible to the shopper, thereby further improving the protection provided by EAS, and also overcoming possible esthetic as well as functional objections to the use of visible EAS tags.

[0020] For further details, reference is made to the detailed description which is provided below, taken in conjunction with the accompanying drawings.

[0021] Advantageous embodiments of the device according to the present invention form the subject-matters of the dependent claims.

[0022] Figure 1 is a flow diagram of the treatment technique of a device according to the present invention.

[0023] Figure 2 is a diagrammatic plan view of a tag according to the invention which is useful in implementing the technique diagrammed in Figure 1.

[0024] Figure 3 is a diagrammatic cross-sectional view of the tag of Figure 2, taken along the line 3-3 in Figure 2.

[0025] Figure 4 is a diagram of the equivalent circuit of the tag of Figure 2.

[0026] In the several figures, like reference numbers denote similar structure.

[0027] Referring to the flow diagram of Figure 1, block 10 represents the manufacturing stage of the articles of merchandise which are to be subjected to a technique described in the following.

[0028] As indicated by block 11, EAS tags are applied to these articles in conjunction with their manufacture.

[0029] Further these tags are then in a state in which they would not be detectable by the particular type of EAS equipment with which they are designed to ultimately function.

[0030] Block 13 represents the distribution channel through which these now-tagged articles then pass on their way to the retail stores.

[0031] Block 14 represents the merchandise receiving facility of one of these retail stores.

[0032] Block 15 represents means, located preferably at store receiving facility 14, for "activating" the EAS tags attached to the articles which reach receiving facility 14 from distribution channel 13. By "activating" is meant rendering these tags detectable by the store's EAS equipment.

[0033] Block 16 represents the retail store in which the received articles, now bearing tags which are detectable, are displayed for retail sale.

[0034] Block 17 represents the means, in store 16, for deactivating those tags which are attached to articles whose removal from store 16 has become authorized, by virtue of the fact that these articles have been properly checked out.

[0035] Block 18 represents the EAS detection equipment with which the store 16 is equipped and the activity of detecting tags which have not been deactivated at checkout.

[0036] In the flow diagram of Figure 1, the manufacturing stage represented by block 10 may be entirely conventional, with the sole exception that EAS tags are applied to the merchandise at that stage. However, this application can also be carried out by various, but well known and conventional means. For example, an EAS tag may simply be adhesively attached either to each article itself, or to the individual package for that article. Since these EAS tags are typically similar in external configuration to a thick piece of paper, 25,4 mm or 50,8 mm (an inch or two) square, and coated on one side with pressure sensitive adhesive, such application may involve nothing more than simply pressing them against a surface of the article or its individual packaging. In this regard, the application procedure may be the same as would previously have been performed at the retail store, itself, except that it can now be performed more efficiently, and more reliably, by means of the same type of machinery which is conventionally used in manufacturing to apply other kinds of tags and labels to articles of merchandise.

[0037] The distribution channel represented by block 13 in Figure 1 may be entirely conventional, comprising the various transportation means for moving merchandise to retail stores, the warehouses in which it is stored, etc. While in this channel, the merchandise is typically contained in bulk packaging, such as cardboard cases, each containing multiple units of the individual articles. These cases now contain articles to which not-yet-detectable EAS tags have already been attached.

[0038] Store receiving facility 14 may also be conventional, in that it comprises the customary unloading location and material handling equipment used by retail stores to receive their merchandise.

[0039] However, there is also provided at this receiving facility 14 the means 15 for activating the heretofore not-detectable tags attached to the received merchandise. How this is done is described later in this specification.

[0040] Thereafter, this received merchandise is treatedinthesame wayasinanyother EAS equipped store. That is, it is processed through store 16 in conventional manner, e.g. by being displayed in the merchandise display area and checked out after being selected by customers for purchase. As part of the checkout operation, the EAS tags are subjected to deactivation by means 17, or alternatively are detected by EAS detection equipment 18 upon unauthorized removal. All of this may be accomplished in completely conventional manner by completely conventional means.

[0041] In particular, the conventional EAS equipment 18 used to detect EAS tags which have not been deactivated by means 17 may be of the so-called swept-frequency RF type. Briefly, this type of equipment transmits a radio frequency (RF) signal whose frequency is periodically varied between, say, 7.4 and 9.0 MHz. The EAS tags for use with this type of equipment comprise an inductor-capacitor (LC) circuit which is resonant within that transmitted band, e.g. at approximately 8.2 MHz. The presence of the EAS tag distorts the RF signal and that distortion is detected by a nearby receiver which then gives an alarm.

[0042] Such swept-frequency RF EAS-detection equipment is disclosed for example, in US-A-3 500 373, US-A-3 810 147 and US-A-3 828 337. As for the deactivating means 17, this may also operate on a swept-frequency RF basis in the 7.4 to 9.0 MHz range. Such deactivatring means is disclosed, for example, in US-A-4 498 076 and in US-A-4 567 473.

[0043] Commercial EAS detection equipment, as well as deactivation equipment of this swept-frequency RF type is available from Checkpoint Systems, Inc. of Thorofare, New Jersey.

[0044] Turning now to Figures 2, 3 and 4, these diagrammatically illustrate a kind of EAST tag according to the present invention, in conjunction with EAS equipment of the above-mentioned swept-frequency RF type.

[0045] This tag 20 comprises a dielectric substrate 21, which may be made of polyethylene and which bears on each side a conductive pattern 22 and 23, respectively, which may be of aluminum.

[0046] As is particularly clearly visible in Figure 2, the angular spiral portion of pattern 22 defines an inductor 22a, while the square portion in the center defines one plate of a capacitor 24. The opposite plate of capacitor 24 is defined by the corresponding square portion of pattern 23 which is shown in phantom by broken lines in Figure 2. One plate of a second, smaller capacitor 25 is defined by the triangular portion at the upper right-hand end of the spiral portion of pattern 22. The opposite plate of this second capacitor 25 is defined by the corresponding triangular portion of pattern 23 shown in phantom by broken lines in Figure 2. Also in pattern 23, a conductive path 26 (shown in phantom by broken lines in Figure 2) connects the plates of capacitors 24 and 25.

[0047] Referring to Figure 4, the equivalent circuit of the EAS tag 20 shown in Figures 2 and 3 is seen to consist of a resonant circuit defined by inductor 22a and capacitors 24 and 25.

[0048] In accordance with the present invention, the tag 20 is further provided with two indentations, 26a and 27. Indentation 26a is formed in capacitor 24, while indentation 27 is formed in capacitor 25.

[0049] Given that the EAS equipment 18 in Figure 1, by which tag 20 is to be ultimately detectable, and the deactivating equipment 17 by which tag 20 is to be ultimately capable of being deactivated, are both of the swept-frequency RF type previously mentioned, with transmitted signals varying in frequency between 7.4 and 9.0 MHz, then the values of inductor 23 and capacitors 24 and 25 are so chosen that tag 20 initially forms an LC circuit which is resonant at a frequency substantially above the 7.4 to 9.0 MHz range, e.g. at a frequency of approximately 18 MHz. The values of inductor 22a and capacitor 24 are further so chosen that, if capacitor 25 is shorted out, then tag 20 forms an LC circuit which is resonant within the 7.4 to 9.0 MHz range, e.g. at approximately 8.2 MHz.

[0050] The above-mentioned US-A-4 498 076 and US-A-4 567 473 disclose the use of indentations such as 26a and 27 provided in capacitors 24 and 25 of tag 20 in order to create a short circuit between the conductive patterns on opposite sides of the dielectric substrate. In these documents, the shorting out is used to deactivate an EAS tag which is designed for use in conjunction with swept-frequency RF EAS equipment.

[0051] In the present invention, the indentation 26a in capacitor 24 is provided for the very same purpose, namely for use in ultimately deactivating tag 20 at state 17 in Figure 1. However, in the present invention, the indentation 27 in the other capacitor 25 is provided for the exact opposite purpose, namely for use in activating tag 20, which had previously been not-detectable at the EAS detection stage 18 in Figure 1.

[0052] The electronic equipment which is used at activation stage 15 in Figure 1 in cooperation with a tag 20 may be the same as illustrated and described in said US-A-4 498 076 and US-A-4 567 473, with two exceptions.

[0053] One exception is that the frequencies at which it operates are in a range which includes the higher frequency (of approximately 18 MHz) at which tag 20 is initially resonant. This higher range may be from 16.5 to 19.5 MHz.

[0054] The other exception is that this electronic equipment operates at a substantially higher power.

[0055] By operating in the higher frequency range, the equipment becomes capable of shorting out the capacitor 25 via indentation 27. By operating at high enough power, it becomes capable of shorting out that same capacitor simultaneously in a plurality of tags 20, such as would be present in a bulk package containing multiple units of merchandise articles to which such tags had been attached at the manufacturing and tag application stage 10, 11 of Figure 1.

[0056] With their capacitors 25 so shorted out, all the tags 20 in the bulk package at receiving facility 14 in Figure 1 have now become activated, and have therefore become detectable at stage 18 in completely conventional manner.

[0057] Moreover, they have now also become deactivatable at stage 17, also in completely conventional manner.

[0058] Detection at stage 18 would result simply from having such an activated tag 20 present in the swept-frequency RF field, whose distortion by that tag is then sensed by the EAS receiver, causing an alarm.

[0059] Deactivation at stage 17 would result from operating as disclosed in said US-A-4 498 076 and US-A-4 567 473, namely by shorting out capacitor 24 via its indentation 26a. With both capacitors 24 and 25 (see Figure 4) so shorted out via respective indentations 26a, 27, the tag 20 again becomes undetectable at stage 18 of Figure 1.

[0060] As previously noted, in order to perform the simultaneous activation of the tags attached to all the articles in a bulk package of merchandise, it may be necessary to operate the activating means 15 at higher power than the deactivating means 17, which is typically used to deactivate only one tag at a time. Such higher power may exceed the limit imposed by regulatory agencies such as the United States Federal Communications Commission. If that should be the case, then a simple treatment is to provide an enclosure which contains the RF fields produced by the activating means and which is large enough to contain both that means and the EAS tag bearing merchandise, still in its bulk package. This enclosure may take any of various conventional forms, such as a metal box. The same treatment, namely enclosure of the activating means and the bulk package, may also be used if the frequency range within which the activating signal is transmitted presents a problem in terms of regulatory requirements. That frequency range is preferably so chosen that it does not include integral multiples of the frequency range within which the deactivation signal is subsequently transmitted. That is to forestall the possibility that the activating signal may also cause deactivation of the now-activated tags due to possible spurious resonances at multiples of the resonant frequency of the activated tags.

[0061] As previously noted, in order to activate tag 20 by changing its resonant frequency from its initial value (e.g. approximately 18 MHz) to its second value (e.g. approximately 8.2 MHz), capacitor 25 is shorted out by the application of a sufficiently strong field at the initial frequency. The total voltage developed by this applied field will appear across the series combination of that capacitor 25 and capacitor 24 (see Figure 4). However, this total voltage will be distributed between those capacitors in inverse proportion to their plate sizes. By making capacitor 25 substantially smaller than capacitor 24, the voltage across the former will always be substantially larger than that across the latter. In view of this, and in view of the fact that the indentations in both may be made substantially similar, capacitor 25 will break down before capacitor 24, as is desired.

[0062] By proceeding in accordance with this technique, it is not necessary to distinguish, in manufacturing or distribution, between products to be delivered to EAS equipped stores and others. Rather, all products can be tagged, and the EAS equipped stores themselves can then activate those which they receive, while other stores need do nothing at all.

[0063] Moreover, these tags can now be applied to the individual articles of merchandise in a manner which would not be convenient for store tagging. For example, there would be no problem, at the manufacturing and tag application stage (10, 11 in Figure 1), to apply EAS tags on the inside of the "bubble pack" or on the inside of a cardboard box containing a particular article. This would have the advantage of concealing the EAS tag, so that a shopper would not even know that this particular article is protected.

[0064] It will be understood that many other variations to use the device according to the invention are possible, without departing from the inventive concept.

[0065] For example, the use is not limited to articles for sale in retail stores. Other applications can also benefit, such as book stores, video stores, etc.

[0066] Also, although the preferred application of the above described technique is to situations in which all the tagged articles in a bulk package are activated simultaneously, it will be understood that the same technique can be utilized to activate these articles after they have been subdivided into smaller quantities, or even one at a time. The other advantages which arise from having applied the tags in conjunction with the manufacture will then still apply.

[0067] Accordingly, it is desired that the scope of the present invention be defined only by the appended claims.

Claims

1. A device (20) for interacting with an electronic article surveillance system wherein said device (20) comprises one and only one inductor (22a), the inductor forming a portion of a resonant circuit, the resonant circuit being responsive to an applied radio-frequency signal generated by said electronic article surveillance system said resonant circuit interacting with said electronic article surveillance system in a first mode of operation for detection of said device (20), in which said resonant circuit is configured to have a single resonance at a first frequency corresponding to an operative frequency of said electronic article surveillance system, and in an initial second mode of operation for activation of said device (20), in which said resonant circuit is configured to have a single resonance at a second frequency corresponding to an activation frequency different from the operative frequency of said electronic article system, said resonant circuit including activating means (27) for modifying said resonant circuit from being capable of resonating at the second frequency to being capable of resonating at the first frequency by exposure of said resonant circuit to the applied radio-frequency signal at the second frequency, and deactivating means (26) for modifying said resonant circuit from being capable of resonating at either the first or the second frequency by exposure of said resonant circuit to an applied radio-frequency signal at the first frequency.

2. The device (20) of claim 1 wherein said resonant circuit is comprised of etched circuit portions (22, 23) formed on opposing sides of a substrate (21), wherein said activation means is an indentation (27), formed at a first selected location along one of said etched portions (22, 23) to define a narrowed space between said etched circuit portions (22, 23) at said first selected location.

3. The device (20) of claim 2, wherein said first location is selected to comprise a series resonant circuit operative at said first frequency following exposure of said device (20) to an applied radio-frequency field at said second frequency.

4. The device (20) of claim 1, wherein said deactivation means is an indentation (26a) formed at a second selected location along one of said etched circuit portions (22, 23) to define a narrowed space between said etched portions (22, 23) at said selected location.

5. The device (20) of claim 4, wherein said second location is selected to develop a short circuit in said series resonant circuit following exposure of said device (20) to an applied radio-frequency field at said first frequency.

6. The device (20) of claim 5, wherein said device (20) is configured so that the indentation (26a, 27) provided at said first location will operate to complete said series resonant circuit before the indentation (26a, 27) provided at said second location will operate to develop a short circuit in said series resonant circuit upon exposing said device (20) to an applied radio-frequency field at said second frequency.

7. The device (20) of claim 4, wherein said series resonant circuit includes two capacitor elements (24, 25), a first of which defines said first location for an indentation (26a, 27) and a second of which defines said second location for an indentation (26a, 27), and wherein the first of said capacitor elements (27) is comprised of plate portions which are smaller than plate portions comprising the second of said capacitor elements (24).

8. A device (20) for use in a system for providing a facility (16) with articles to which said device (20) has been attached, said device (20) being capable of being detected by an electronic article surveillance system, said system for providing a facility with articles comprising:

means for attaching to said articles, before they reach said facility, said device (20) which is not capable of being detected by said electronic article surveillance system at the time it is attached, but which is capable of being activated to become capable of being so detected;

means (13) for supplying said articles to said facility (16);

means (15) operative at a second frequency for activating said device (20) upon receipt at said facility (16); and said electronic article surveillance system comprising:

means (18) operative at a first frequency for detecting said device (20); and

means (17) operative at a first frequency for deactivating said device (20), wherein said device (20) comprises a single tuned resonant circuit having two capacitors (24, 25) and one and only one inductor (22a) said single tuned resonant circuit being resonant at said second frequency as supplied to said facility, and activating means (27) for selectively disabling one of said capacitors (24, 25) whereby said circuit becomes resonant at said first frequency.

9. The device of claim 8, wherein said capacitors (24, 25) are of different sizes and said disabling means comprises an indentation (26a, 27) in one of said capacitors (24, 25).

10. The device of claim 9, wherein there is also an indentation (26a, 27) in the other one of said capacitors (24, 25).

Ansprüche

1. Vorrichtung (20) zum Zusammenwirken mit einem elektronischen Warenüberwachungssystem, wobei die Vorrichtung (20) eine und nur eine Drosselspule (22a) aulweist, die einen Teil eines Schwingkreises bildet, wobei der Schwingkreis auf ein angelegtes Hochfrequenzsignal anspricht, das durch das elektronische Warenüberwachungssystem erzeugt wird, wobei der Schwingkreis mit dem elektronischen Warenüberwachungssystem in einer ersten Betriebsart zum Erfassen der Vorrichtung (20) zusammenwirkt, in welcher der Schwingkreis so konfiguriert ist, daß er eine einzelne Resonanz bei einer ersten Frequenz hat, die einer Betriebsfrequenz des elektronischen Warenüberwachungssystems entspricht, und in einer anfänglichen zweiten Betriebsart zum Aktivieren der Vorrichtung 20, in welcher der Schwingkreis so konfiguriert ist, daß er eine einzelne Resonanz bei einer zweiten Frequenz hat, die einer Aktivierungsfrequenz entspricht, welche von der Betriebsfrequenz des elektronischen Warenüberwachungssystems verschieden ist, wobei der Schwingkreis eine Aktivierungseinrichtung 27 aufweist zum Modifizieren des Schwingkreises so, daß er nicht mehr in der Lage ist, bei der zweiten Frequenz in Resonanz zu schwingen, sondern in der Lage ist, bei der ersten Frequenz in Resonanz zu schwingen, indem der Schwingkreis mit dem Hochfrequenzsignat bei der zweiten Frequenz beaufschlagt wird, und eine Deaktiviereinrichtung (26) zum Modifizieren des Schwingkreises derart, daß er weder bei der ersten noch bei der zweiten Frequenz in Resonanz schwingen kann, indem der Schwingkreis mit einem angelegten Hochfrequenzsignal mit der ersten Frequenz beaufschlagt wird.

2. Vorrichtung 20 nach Anspruch 1, wobei der Schwingkreis aus geätzten Schaltungsteilen (22, 23) besteht, die auf entgegengesetzten Seiten eines Substrats (21) gebildet sind, wobei die Aktiviereinrichtung eine Vertiefung (27) ist, die an einer ersten ausgewählten Stelle längs einem der geätzten Teile (22, 23) gebildet ist, um einen schmalen Raum zwischen den geätzten Schaltungsteilen (22, 23) an der ersten ausgewählten Stelle zu definieren.

3. Vorrichtung 20 nach Anspruch 2, wobei die erste Stelle so ausgewählt wird, daß sie einen Serienschwingkreis umfaßt, der bei der ersten Frequenz operativ ist, nachdem die Vorrichtung (20) mit einem aufgebauten Hochfrequenzfeld mit der zweiten Frequenz beaufschlagt worden ist.

4. Vorrichtung 20 nach Anspruch 1, wobei die Deaktiviereinrichtung eine Vertiefung (26a) an einer zweiten ausgewählten Stelle längs eines der geätzten Schaltungsteile (22, 23) ist, die einen verschmälerten Raum zwischen den geätzten Teilen (22, 23) an der ausgewählten Stelle bildet.

5. Vorrichtung 20 nach Anspruch 4, wobei die zweite Stelle so ausgewählt wird, daß in dem Reihenschwingkreis ein Kurzschluß vorhanden ist, nachdem die Vorrichtung 20 mit einem aufgebauten Hochfrequenzfeld mit der ersten Frequenz beaufschlagt worden ist.

6. Vorrichtung 20 nach Anspruch 5, wobei die Vorrichtung 20 so konfiguriert ist, daß die Vertiefung (26a, 27), die an der ersten Stelle vorgesehen ist, bewirken wird, daß der Reihenschwingkreis geschlossen wird, bevor die Vertiefung (26a, 27), die an der zweiten Stelle vorgesehen ist, wirksam wird, um einen Kurzschluß in dem Reihenschwingkreis bei Beaufschlagung der Vorrichtung 20 mit einem aufgebauten Hochfrequenzfeld mit der zweiten Frequenz zu bilden.

7. Vorrichtung 20 nach Anspruch 4, wobei der Reihenschwingkreis zwei Kondensatorelemente 24, 25 aufweist, von denen ein erster die erste Stelle für eine Vertiefung (26a, 27) definiert und von denen ein zweiter die zweite Stelle für eine Vertiefung (26a, 27) definiert und wobei das erste und das zweite Kondensatorelement (27) aus Belagteilen besteht, die als die Belagteile, welche das zweite der Kondensatorelemente (24) umfaßt.

8. Vorrichtung 20 zur Verwendung in einem System zum Versorgen eines Geschäfts (16) mit Waren, an denen die Vorrichtung 20 befestigt worden ist, wobei die Vorrichtung 20 in der Lage ist, durch ein elektronisches Warenüberwachungssystem erfaßt zu werden, wobei das System zum Versorgen eines Geschäfts mit Waren umfaßt: eine Einrichtung zum Befestigen an den Waren, bevor diese das Geschäft erreichen, der Vorrichtung 20, die zu der Zeit, zu der sie befestigt wird, nicht durch das elektronische Warenüberwachungssystem erfaßbar ist, die aber aktivierbar ist, um so erfaßbar zu werden;
eine Einrichtung (13) zum Liefern der Waren zu dem Geschäft (16);
eine Einrichtung (15, die bei der zweiten Frequenz wirksam ist, um die Vorrichtung (20) nach Empfang in dem Geschäft (16) zu aktivieren; und
wobei das elektronische Warenüberwachungssystem umfaßt:

eine Einrichtung (18), die bei der ersten Frequenz wirksam ist, um die Vorrichtung (20) zu erfaßen; und

eine Einrichtung (17), die bei der ersten Frequenz wirksam ist, um die Vorrichtung (20) zu deaktivieren, wobei die Vorrichtung (20) einen einzelnen abgestimmten Schwingkreis umfaßt, der zwei Kondensatoren (24, 25) und nur eine Drosselspule (22a) aufweist, wobei der einzelne abgestimmte Schwingkreis bei der zweiten Frequenz in Resonanz schwingt, so wie er zu dem Geschäft geliefert worden ist und eine Aktiviereinrichtung (27) zum wahlweisen Unwirksammachen von einem der Kondensatoren (24, 25), wodurch die Schaltung in die Lage versetzt wird, bei der ersten Frequenz in Resonanz zu schwingen.

9. Vorrichtung nach Anspruch 8, wobei die Kondensatoren (24, 25) unterschiedliche Größen haben und wobei die Inaktiviereinrichtung eine Vertiefung (26a, 27) in einem der Kondensatoren (24, 25) umfaßt.

10. Vorrichtung nach Anspruch 9, wobei es auch eine Vertiefung (26a, 27) in dem anderen der Kondensatoren (24, 25) gibt.

Revendications

1. Dispositif (20) destiné à entrer en interaction avec un système électronique de surveillance d'objets, dans lequel ledit dispositif (20) comprend une et une seule inductance (22a), l'inductance constituant une partie d'un circuit résonant, le circuit résonant étant sensible à l'application d'un signal radiofréquence généré par ledit système électronique de surveillance d'objets, ledit circuit résonant entrant en interaction avec ledit système électronique de surveillance d'objet selon un premier mode de fonctionnement destiné à la détection dudit dispositif (20), dans lequel ledit circuit résonant possède une configuration telle qu'il a une résonance unique à une première fréquence correspondant à une fréquence de fonctionnement dudit système électronique de surveillance d'objets, et dans lequel, selon un deuxième mode initial de fonctionnement destiné à l'activation dudit dispositif (20), ledit circuit résonant possède une configuration telle qu'il a une résonance unique à une deuxième fréquence correspondant à une fréquence d'activation différente de la fréquence de fonctionnement dudit système électronique de surveillance d'objets, ledit circuit résonant comprenant un moyen d'activation (28) destiné à modifier ledit circuit résonant pour le faire passer de la capacité à résonner à la deuxième fréquence à la capacité à résonner à la première fréquence par exposition dudit circuit résonant à l'application du signal radiofréquence à la deuxième fréquence, et un moyen de désactivation (26) destiné à modifier ledit circuit résonant pour lui retirer la capacité à résonner soit à la première fréquence, soit à la deuxième fréquence, par exposition dudit circuit résonant à l'application du signal radiofréquence à la première fréquence.

2. Dispositif (20) selon la revendication 1, dans lequel ledit circuit résonant est composé de parties de circuit gravées (22, 23) constituées sur les côtés opposés d'un substrat (21), dans lequel ledit moyen d'activation est une entaille (27), formée en un premier emplacement choisi le long de l'une desdites parties gravées (22, 23) afin de définir un espace plus étroit entre lesdites parties gravées (22, 23) audit premier emplacement choisi.

3. Dispositif (20) selon la revendication 2, dans lequel ledit premier emplacement est choisi de manière à comprendre un circuit résonant série fonctionnant à ladite première fréquence à la suite de l'exposition dudit dispositif (20) à un champ radiofréquence appliqué à ladite deuxième fréquence.

4. Dispositif (20) selon la revendication 1, dans lequel ledit moyen de désactivation est une entaille (26a) formée en un deuxième emplacement choisi le long de l'une desdites parties de circuit gravées (22, 23) afin de définir un espace plus étroit entre lesdites parties gravées (22, 23) audit emplacement choisi.

5. Dispositif (20) selon la revendication 4, dans lequel ledit deuxième emplacement est choisi de manière à développer un court-circuit dans ledit circuit résonant série à la suite de l'exposition dudit dispositif (20) à un champ radiofréquence appliqué à ladite première fréquence.

6. Dispositif (20) selon la revendication 5, dans lequel ledit dispositif (20) possède une configuration telle que l'entaille (26a, 27) prévue dans ledit premier emplacement fonctionne pour compléter ledit circuit résonant série avant que l'entaille (26a, 27) prévue dans ledit deuxième emplacement ne fonctionne pour développer un court-circuit dans ledit circuit résonant série à l'exposition dudit dispositif (20) à un champ radiofréquence appliqué à ladite deuxième fréquence.

7. Dispositif (20) selon la revendication 4, dans lequel ledit circuit résonant série comprend deux éléments de condensateurs (24, 26), le premier d'entre eux définissant ledit premier emplacement pour une entaille (26a, 27) et le deuxième d'entre eux définissant ledit deuxième emplacement pour une entaille (26a, 27), et dans lequel le premier desdits éléments de condensateur (26) est composé de parties de plaques qui sont plus petites que les parties de plaques composant le deuxième desdits éléments de condensateur (24).

8. Dispositif (20) prévu pour l'emploi dans un système destiné à fournir une installation (16) munie d'objets auxquels ledit dispositif (20) a été fixé, ledit dispositif (20) étant capable d'être détecté par un système électronique de surveillance d'objets, ledit système étant destiné à fournir une installation (16) munie d'objets comprenant :

un moyen de fixation aux dits articles, avant qu'ils n'atteignent ladite installation, ledit dispositif (20) n'étant pas capable d'être détecté par ledit système électronique de surveillance d'objets à l'instant auquel il est fixé, mais étant capable de se voir activé afin de devenir capable d'être détecté ;

un moyen (13) destiné à fournir lesdits articles à ladite installation (13) ;

un moyen (15) fonctionnant à une deuxième fréquence, destiné à activer ledit dispositif (20) lors de sa réception à ladite installation (16) ; et ledit système électronique de surveillance d'objet comprenant :

un moyen (18) fonctionnant à une première fréquence, destiné à détecter ledit dispositif (20) ; et

un moyen (17) fonctionnant à une première fréquence, destiné à désactiver ledit dispositif (20), dans lequel ledit dispositif (20) comprend un circuit résonant à accord unique comportant deux condensateurs (24, 25) et une et seulement une inductance (22a), ledit circuit résonant à accord unique étant résonant à ladite deuxième fréquence quand il est fourni à ladite installation, et un moyen (27) d'activation destiné à mettre hors service sélectivement l'un desdits condensateurs (24, 25), à la suite de quoi ledit circuit devient résonant à ladite première fréquence.

9. Dispositif selon la revendication 8, dans lequel lesdits condensateurs (24, 25) sont de tailles différentes et dans lequel ledit moyen de mise hors service comprend une entaille (26a, 27) dans l'un desdits condensateurs (24, 25).

10. Dispositif selon la revendication 9, dans lequel il y a aussi une entaille (26a, 27) dans l'autre desdits condensateurs (24, 25).

Drawing