Patent Application
20060187054
The present invention relates to a decision machine of detection tag using magnetic field, used for confirmation of the deactivation of a magnetic detection tag (hereinafter referred to also as detection tag or EM tag). More particularly, the present invention relates to a decision machine of detection tag using magnetic field, which is used for confirming, after the deactivation operation of a detection tag, whether or not the detection tag has been deactivated reliably by a deactivation operation.
Detection tags using a magnetic field as a detection means are known. They are attached to goods, etc., are carried with the goods and, when passing through particular gates, are detected by the gates; thereby, the circulation of goods is controlled and the theft of goods is prevented (claim 1 of JP 1994-342065A). Such a detection tag using a magnetic field is also called EM (electric magnetic) tag.
On the other side of the soft magnetic substance layer 160 is laminated a release liner 169 via a pressure-sensitive adhesive layer 168.
In using this detection tag, the release liner 169 is peeled and the release liner 169-removed detection tag is adhered to goods or the like to be controlled.
Incidentally, 174 is a detection tag. When the detection tag 174 moves between the gates 170 and 172 to a direction indicated by an arrow R, in a state fitted to goods, etc. (not shown), the magnetic field S formed between the gates 170 and 172 is distorted by the detection tag 174. By detecting this distortion of the magnetic field S using the detector (not shown), the passing of the detection tag 174 between the gates 170 and 172 is detected.
In
For example, when goods or the like purchased normally is in a state that it can be carried out, the detection tag 174 adhered to the goods or the like is deactivated beforehand. Owing to this deactivation operation, there occurs no distortion of magnetic field when the detection tag 174 adhered to the goods or the like is passed between gates 170 and 172. Consequently, the detection tag adhered to the goods or the like is not detected during the passing between the gates and the goods or the like is carried outside.
Meanwhile, when the goods or the like is carried out illegally, the detection tag 174 adhered thereto is in a state not deactivated. Therefore, when the goods or the like containing the detection tag 174 not deactivated is passed between gates 170 and 172, distortion of magnetic field takes place. Detection of this distortion of magnetic field can detect illegal take-out of goods or the like.
Deactivation of detection tag can be achieved by magnetizing the hard magnetic substance layer 165 of detection tag shown in
When the detection tag shown in
In deactivating a detection tag by using a conventional deactivation machine, however, all the detection tags subjected to the deactivation are not always deactivated reliably and there are cases of no deactivation. In such cases, even the commodities purchased legally are detected at gates and are regarded as illegally purchased commodities, causing a big problem.
In order to solve this problem, the present inventors proposed a deactivation machine comprising the above-mentioned deactivation machine using permanent magnets and a means for confirmation of deactivation, fitted thereto (Japanese Patent Application 2004-322700). This means for confirmation of deactivation comprises total two loop coils each having a function of generating a magnetic field and a function of detecting the reflected signal from a detection tag, and a signal-detecting circuit.
In the means for confirmation of deactivation, the two loop coils generate magnetic fields. Any detection tag which has not been deactivated successfully, reflects the generated magnetic fields and the reflected signals are received by the two loop coils. The reflected signals received are taken out as a differential signal of the two loop coils and thereby the deactivation or non-deactivation of detection tag is confirmed.
In the deactivation machine proposed above, it was found that the detectability of the means for confirmation of deactivation may be low depending upon the entering direction when a detection tag enters a deactivation surface (a surface at which magnets are arranged alternately). For example, the detection sensitivity for a detection tag entering the periphery of the deactivation surface may be low. In such a case, deactivation state of a detection tag subjected to deactivation operation may not be decided correctly.
The present inventors made a study in order to solve the above problem and thought of a cross coil constituted by a plurality of coils for magnetic field generation which have been wound so as to form a predetermined differential angle between the central axes of the individual coils. By supplying AC powers of different phases to this cross coil, the magnetic field generated by the cross coil become uniform. As a result, variation of the detection sensitivity for detection tag, which occurs depending upon the entering site of detection tag, can be eliminated.
The present invention has been completed based on the above finding. Accordingly, the present invention aims at providing a decision machine of detection tag using magnetic field, which can reliably confirm the deactivation of detection tag irrespectively of the entering site of detection tag.
The present invention, which has achieved the above aim, is as described below.
a cross coil constituted by a plurality of individual coils which have been wound round a frame member so as to form a predetermined differential angle between the central axes of the individual coils,
a magnetic power supply part comprising an oscillator for generating an AC power and a phase modulator for differing each other the phase of AC power generated by the oscillator, by a predetermined differential angle, to supply powers of different phases to the individual coils,
a signal processor part connected to the plurality of individual coils, and
a decision part for deciding the output signal sent from the signal processor part.
a cross coil constituted by a plurality of individual coils which have been wound round a frame member so as to form a predetermined differential angle between the central axes of the individual coils,
a magnetic power supply part comprising an oscillator for generating an AC power and a phase modulator for differing each other the phase of AC power generated by the oscillator, by a predetermined differential angle, to supply powers of different phases to the individual coils,
at least one detection coil provided parallel to a plane including the central axes of the individual coils,
a signal processor part connected to the at least one detection coil, for processing the output signal of the detection coil, and
a decision part for deciding the output signal sent from the signal processor part.
In the decision machine of detection tag using magnetic field according to the present invention, there is used, as a coil for magnetic field generation, a cross coil constituted by a plurality of individual coils which have been wound so as to form a predetermined differential angle between the central axes of the individual coils. Therefore, a reduction in the detection sensitivity for detection tag, which occurs depending upon the entering site of detection tag, can be eliminated with no necessity of intensifying the electric current supplied to the coils. As a result, the deactivation of detection tag can be confirmed reliably. Thus, there can be reliably avoided a mistake by which a non-deactivated detection tag is detected at gates.
In these drawings, 22 is a cross coil; 24 is a magnetic power supply part; 26 is a detection tag; 28, 28a and 28b are each a signal processor part; 30 is a decision part; 42 and 62 are each a frame member; 44, 48, 64, 66 and 68 are each a coated conductor.
46 is a first individual coil; X, Y and Z are each an arrow; 50 is a second individual coil; a is an angle formed by the central axes of individual coils; 32 is an oscillator; 34 is a phase modulator; 910 is a cross coil; 82 is a detection coil; 83 is a substrate; 84a to 84i are each a small coil; 94a and 94b are each a circular planar coil; 95 is a magnetic power supply part; and P is a differential output.
Embodiments of the present invention are described in detail below with referring to the accompanying drawings.
To the cross coil 22 are supplied a plurality of AC powers of different phases from a magnetic power supply part 24. Owing to this supply of powers, an alternating magnetic field is formed along the surface of the cross coil 22. When a detection tag 26 is moved along the surface (the upper surface in
A coated conductor 48 is wound on the outer surface of the first individual coil 46 along the opposing two sides of the frame member 42 which are different from the above-mentioned two opposing sides, whereby a flat, second individual coil 50 is formed. Accordingly, the direction of the central axis of the second individual coil 50, i.e. the direction of the magnetic flux formed by the second individual coil 50 is the direction of an arrow Y shown in Fig. l(a). Thus, the first individual coil 46 and the second individual coil 50 have respective central axes on the same plane and the angle a formed by the two central axes is 90°.
As to the size of the cross coil 22, there is no particular restriction. The size may be such that, when the detection tag 26 is moved along the upper surface of the cross coil 22, the deactivation of the detection tag 26 can be ascertained magnetically. The movement distance of the detection tag 26, necessary for magnetic ascertainment of the deactivation of the detection tag 26 is preferred to be generally 30 mm or more and, from the standpoint of practical application, 30 to 100 mm.
A second individual coil 50 is supplied the other AC power portion of the same phase generated by the oscillator 32. Therefore, the first individual coil 46 and the second individual coil 50 are supplied AC powers of different (by 90°) phases. As a result, the distribution of the magnetic field intensity above the cross coil 22 becomes highly uniform. Consequently, any non-deactivated detection tag 26 which enters above the upper surface of the cross coil 22, can be detected reliably irrespectively of the entering site of the detection tag 26.
The Alternating magnetic field above the cross coil 22, which has been distorted by entering of the detection tag 26, is detected by the first individual coil 46 and the second individual coil 50; the detected signals are sent to signal processor parts 28a and 28b, and are subjected to processings such as Fourier transform, filtration and the like; then, the deactivation or non-deactivation of the detection tag 26 is ascertained by a decision part 30.
When the number of individual coils is n, the angle a formed by each two adjacent central axes of the individual coils is most preferably:
α=180/n (degree)
The angle α is not restricted to the above and may be:
α=180/n±180/2n (degree)
because this angle functions with no substantial problem.
The magnetic field intensity generated by the individual coils is preferably 120 A/m or more at the detection site of detection tag and 150 to 250 A/m from the standpoint of practical application.
In the second embodiment, a magnetic field is generated by a cross coil and the distortion of the magnetic field caused by a detection tag is detected by a detection coil which is different from the cross coil and provided separately.
In
In
This distortion of magnetic field is detected by a detection coil 82 provided above the cross coil 22; the detected signals are subjected to processings such as Fourier transform, filtration and the like at a signal processor part 28; then, the deactivation or non-deactivation of the detection tag 26 is ascertained at a decision part 30.
As described above, by arranging a plurality of small coils 84a to 84i, a large detection area is secured. Further, since the signals of distorted magnetic fields are taken as a differential output P of the individual small coils, external noises are cancelled, resulting in a higher detection accuracy.
In the above description, the detection coil 82 was provided above the cross coil 22. However, the detection coil 82 may be provided below the cross coil 22, as shown in
There were produced decision machines of detection tag using magnetic field, described in the following Examples and Comparative Example, and they were examined for the decision ability of deactivation of detection tag.
There were used detection tags whose detection distance had been adjusted to 10 mm. The detection distance was measured using gates for prevention of shoplifting, EG-C45 (a product of LINTEC CORPORATION).
The above detection tag was moved parallel to the surface of detection coil at a speed of 0.5 m/sec and there was obtained decisions of the machine. From the result there was examined the detection accuracy of the decision machine of detection tag using magnetic field. The distance between the detection tag moved parallel to the surface of detection coil and that of detection coil was maintained at 15 mm.
There was produced a decision machine of detection tag using magnetic field, having a constitution shown in
The first individual coil 46 and the second individual coil 50 were supplied alternate currents of 306 Hz and 1.2 A, which differed in phase by 90°.
The output signals from the two individual coils were subjected to Fourier transform at two signal processor parts 28a and 28b, as shown in
There was produced a decision machine of detection tag using magnetic field, having a constitution shown in
Cross Coil
A first individual coil 46 was formed by winding an enamel-coated copper wire of 0.5 mm in diameter 200 times along the two opposing sides of a frame member of rectangular prism shape, made of flat wooden plate having a width of 120 mm, a depth of 120 mm and a height of 30 mm. Then, an enamel-coated copper wire of 0.5 mm in diameter was wound 200 times round the first individual coil 46 to form a second individual coil 50, in such a way that the central axes of the first individual coil 46 and the second individual coil 50 formed an angle of 90°. Thereby, a cross coil 22 was produced.
The first individual coil 46 and the second individual coil 50 were supplied alternate currents of 306 Hz and 1.2 A, which differed in phase by 90°.
Detection Coil
An enamel-coated copper wire of 0.2 mm in diameter was wound 60 times clockwise in a circular ring shape of 20 mm in diameter, to form nine cylindrical coils each having a height of 2 mm. These nine coils were arranged on a cork plate-made substrate 83 in three lengthwise rows and three crosswise rows (each row contained three coils) so that the center-to-center distance between two adjacent coils was 30 mm and the central axis directions of all the coils became parallel to one another. Further, all the coils were connected in series so that the current directions of each two adjacent coils became opposite to each other.
The thus-produced detection coil 82 was provided in such a way that the lower side of each cylindrical coil was 10 mm apart from the upper surface of the cross coil 22, as shown in
In the detection coil 82, the current directions of each two adjacent coils are opposite to each other; therefore, the detection coil 82 is a kind of differential circuit. The total current (signal) of all the nine coils was sent to a signal processor part 28 and subjected to Fourier transform for conversion into frequency components. The frequency components obtained included, besides the frequency component 306 Hz of the supplied AC power, harmonic components which were 2, 3, 4, . . . times of 306 Hz. The presence of such harmonic components was examined by a decision part 30. Based on the result, the deactivation or non-deactivation of detection tag was ascertained. The result is shown in Table 1.
As shown in
In this decision machine of detection tag using magnetic field, alternate currents each of 306 Hz and 0.2 A, having the same phase were sent from a magnetic electric supply part 95 to the circular planar coils 94a and 94b, to generate an Alternating magnetic field. In this state, a detection tag 26 was allowed to enter the surface of the circular planar coil 94a horizontally with a distance of 15 mm kept between the detection tag and the surface of the circular planar coil 94a.
The differential output of the currents of the two circular planar coils 94a and 94b was taken out and the signal was subjected to Fourier transform at a signal processor part 28. The presence in the frequency components obtained, of harmonic components (306 Hz×2, 3, 4, . . .) besides the frequency component 306 Hz of the supplied alternate current was examined at a decision part 30. Based on the result, the deactivation or non-deactivation of detection tag was ascertained. The result is shown in Table 1.
A detection tag was allowed to enter the periphery or center of the upper side (detection surface) of a cross coil 22 or a circular planar coil, from the lengthwise direction (a direction parallel to the arrow Y of
D: There was detection of detection tag.
N: There was no detection of detection tag.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-31266 | Feb 2005 | JP | national |
