REMOTE IDENTIFICATION DEVICE
TECHNICAL FIELD The present invention relates to a remote identification device .
The present invention may be used to advantage for protecting retail articles against imitation and shoplifting, to which the following description refers purely by way of example. BACKGROUND ART
In the retail business, there is increasing demand for a means of identifying articles at a distance, particularly for the purpose of preventing shoplifting. One of the most commonly used methods of preventing shoplifting is to use magnetic, magnetic-acoustic or chipless RF markers, which are either fixed permanently to the articles or can only be removed using specially designed tools not for sale to the public. At present, such markers are applied by retail operators, which poses various problems, by being relatively expensive, and by the marker normally being recognizable and therefore subject to tampering. As a result, there is increasing
demand on the part of retailers for manufacturers to incorporate the markers in the articles at the production stage (so-called "source marking") .
A more recent development is to combine or replace magnetic markers with radio-frequency identification devices, in particular transponders, which can be provided with a programmable memory for storing a relatively large mass of data, unlike magnetic markers, which are normally limited to a presence-indicating function. On the other hand, transponders have the drawback of being unreliable, by being put out of use when surrounded by a conducting metal element, such as aluminium foil, to shield the electric field.
To be read at a suitable distance to prevent imitation and shoplifting, currently marketed transponders must be relatively large, which therefore makes them difficult to apply to the articles at the manufacturing stage.
DISCLOSURE OF INVENTION It is an object of the present invention to provide a remote identification device designed to eliminate the aforementioned drawbacks, and which, at the same time, is cheap and easy to produce, and is small enough to be applied easily to a respective article during manufacture of the article.
According to the present invention, there is provided a remote identification device as claimed in Claim 1.
The present invention also relates to a support for producing a remote identification device.
According to the present invention, there is provided a support for producing a remote identification device and as claimed in Claim 23.
It is a further object of the present invention to provide a transponder for producing a remote identification device, and which is designed to eliminate the aforementioned drawbacks, while at the same time being cheap and easy to produce, and small enough to apply the remote identification device easily to a respective article during manufacture of the article.
According to the present invention, there is provided a transponder as claimed in Claim 2 . BRIEF DESCRIPTION OF THE DRAWINGS
A number of non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Figure 1 shows a schematic view in perspective of a remote identification device in accordance with the present invention;
Figure 2 shows a further embodiment of the Figure 1 identification device;
Figure 3 shows a further embodiment of the Figure 1 identification device.
BEST MODE FOR CARRYING OUT THE INVENTION
Number 1 in Figure 1 indicates as a whole a remote identification device comprising a support 2 in the form
of a label, i.e. much greater in width and length than in thickness. More specifically, remote identification device 1 falls within the category known commercially as "smart labels", which comprises identification devices in the form of a thin film and possibly with a surface printable on both sides. Smart-label identification devices can normally be made of various dielectric materials, such as paper, PVC, PET, and polyamide (the latter normally used for clothing labels) . Identification device 1 comprises a transponder 3 housed in a portion 4 of support 2; and a magnetic marker 5 housed in a portion 6 of support 2, longitudinally alongside portion 4. More specifically, support 2 in the accompanying drawings is 22 mm wide, 48 mm long, and less than 0.1 mm thick; portion 4 is 16 mm wide and 48 mm long; and portion 6 is 6 mm wide and 48 mm long.
Various tests have shown that the Figure 1 arrangement of portions 4 and 6 of support 2 enables both transponder 3 and magnetic marker 5 to operate independently with no harmful mutual interference.
Transponder 3 comprises an integrated microcircuit 7; and an antenna system 8 in turn comprising a flat, annular radiating" antenna 9 connected to integrated microcircuit 7. More specifically, antenna 9 is polygonal (rectangular in Figure 1) and covers the whole surface area of portion 4. In a different embodiment not shown, antenna 9 is fractal-shaped, e.g. in the form of a tree or Serpinski fractal, to increase its efficiency for a
given covered surface area. Tests have shown the importance of maintaining a width to length ratio of antenna 9 of 1:2.7 to 1:3.2, with a typical value of 1:3, to achieve the best possible efficiency of antenna system 8.
Magnetic marker 5 comprises one or more wires 10, each of which comprises a combination of textile fibers and fibers of amorphous magnetic material with weak ferromagnetic or magnetostrictive properties, and is of the type described in Patent Application WO-0153575-A1 included herein by way of reference. Wires 10 are extremely small (about 30 micron in diameter) , are mechanically strong, freely pliable and chemically resistant, and can be embedded in plastic material for improved heat and chemical protection. Various types of textile fibers can be used, e.g. natural fibers (cotton, wool) , synthetic fibers (polyester, polyamide, polypropylene, nylon), and semisynthetic fibers.
In a preferred embodiment, wires 10 acting as identification elements are associated with an enabling/disabling element for enabling or disabling remote recognition of wires 10. In a preferred embodiment, the enabling/disabling element is formed as described in Patent Application WO-9953458-A1 or WO- 0163577-A1, which are included herein by way of reference. Alternatively, the enabling/disabling element may be selected from known magnetic marker disabling elements, such as low-permeability semisolid magnetic
elements .
A further embodiment (not shown) may employ a group of separate, substantially parallel wires 10 sized and arranged to form a remote-readable binary identification code .
In actual use, identification device 1 can be applied easily to a respective article - in particular in the form of a label applied to an item of clothing - during manufacture of the article, by virtue of being small, mechanically strong, and printable on both sides, and, once applied to a respective article, may provide for safeguarding against shoplifting and imitation, and also for storing the history of the article. The shoplifting function is substantially performed by magnetic marker 5, which indicates its presence and cannot be easily shielded; while the imitation and history-storing functions are performed by transponder 3, which has a programmable memory (typically programmable about 100,000 times) for storing a relatively large amount of data. Magnetic marker 5 can be enabled and disabled repeatedly by the enabling/disabling element. More specifically, magnetic marker 5 is enabled when the article is displayed at the retail outlet, is disabled when the article is legitimately sold, and can be re- enabled if the article is returned to the retail outlet (e.g. to change the size of the article) .
Figures 2 and 3 show two alternative embodiments of antenna system 8 to enhance the efficiency of antenna
system 8 with substantially no change in the surface area of portion 4 of support 2.
In Figure 2, antenna system 8 comprises flat, annular radiating antenna 9 connected to integrated microcircuit 7; and a flat, annular reflecting/directing antenna 11 having a capacitive tuning element 12. In an alternative embodiment not shown, reflecting/directing antenna 11 has no capacitive tuning element 12. Radiating antenna 9 is coplanar with and surrounded by reflecting/directing antenna 11; and antennas 9 and 11 are designed to resonate at operating frequency, i.e. at the frequency of the RF (radio-frequency) field generated by a remote recognition device or so-called "reader" for remote reading/writing transponder 3. Antennas 9 and 11 are located and oriented so that the effect of their mutual inductance is greater than that produced by the sum of their individual inductances, and so that the capacitances required for tuning to the operating frequency are more or less perfect . Antennas 9 and 11 are polygonal (rectangular in Figure 2) . In a different embodiment not shown, antennas 9 and/or 11 are fractal-shaped, e.g. in the form of a tree or SerpinsTi fractal, to increase efficiency for a given covered surface area. Antenna 11 covers the whole surface area of portion 4; while antenna 9 is located within antenna 11, and covers a surface area of 25% to 33% of the surface area of antenna 11. Obviously, in this embodiment, the length ratio of the sides of antenna 9
can no longer be 1:3, and is substantially close to 1:1. Tests have shown the importance of maintaining a width to length ratio of antenna 11 of 1:2.7 to 1:3.2, with a typical value of 1:3, to achieve the best possible efficiency of antenna system 8. The mutual arrangement of antennas 9 and 11 to achieve maximum efficiency of antenna system 8 can be determined experimentally, and has generally been found to be that in which integrated microcircuit 7 and capacitive element 12 are located close to each other (as shown in Figure 2) .
The alternative embodiment in Figure 3 employs a further reflecting/directing antenna 13 substantially identical with reflecting/directing antenna 11 and having a respective capacitive tuning element 14. Antennas 11 and 13 are parallel, are positioned facing, but not coplanar with, each other, are separated by a given distance to achieve between them a relatively high capacitance, and function substantially like the plates of a parallel-plate capacitor. Support 2 comprises three superimposed, firmly connected layers 15, 16 and 17; end layer 15 houses integrated microcircuit 7, antenna 9, magnetic marker 5 and' antenna 11;" end layer 16 houses antenna 13; and intermediate layer 17 is located between end layers 15 and 16 to separate them and, if necessary, provide them with adequate mechanical support.
Preferably, end layers 15 and 16 are made of respective plastic films (typically PVC, PET or
polyamide) or paper; and intermediate layer 17 is made of a film of dielectric material, and is of a thickness, e.g. 0.02 to 0.08 mm, depending on the desired capacitance between antennas 11 and 13. Using further reflecting/directing antenna 13 as an inductor resonating at operating frequency increases the efficiency of antenna system 8 as a whole by accurately determining the frequencies and by increasing efficiency by mutual capacitance. The mutual inductance of antennas 9 and 11 is sufficient to enable integrated microcircuit 7 to operate with antenna system 8 with no further capacitive elements connected parallel to antenna 9, the elimination of which provides for excellent reception/transmission characteristics of transponder 3, for steady performance (by eliminating dispersion due to the manufacturing tolerance in the capacitance value) , and for cheaper fabrication.
The size, shape and position of antennas 9, 11 and 13 are normally determined by testing to achieve the desired performance of antenna system 8.
As shown in the accompanying drawings, in use, portions 4 and 6 of support 2 can be separated along a parting line 18 to separate transponder 3 from magnetic marker 5 in the event transponder 3 and magnetic marker 5 are to be used separately or located in different positions on a respective article.
Identification device 1 described above has numerous
advantages by being recognizable by both a transponder reading device and a conventional magnetic detector, and can therefore be used with existing security systems based exclusively on magnetic detectors. Moreover, identification device 1 is cheap and easy to produce and apply to articles, by virtue of the compact size of transponder 3, which also provides for highly efficient reception/transmission by virtue of the particular arrangement of antenna system 8 as shown in Figures 2 and 3.