JP3310806B2 - Identification signs and anti-theft systems - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an identification sign used for identifying an article or the like, and a theft prevention system using the identification sign.

[0002]

2. Description of the Related Art Conventionally, as identification marks used for theft prevention, for example, Fe, Co and the like disclosed in JP-A-55-143695 and JP-A-58-39396 are disclosed. An identification mark formed of a ferromagnetic amorphous metal piece is known.

Since the direction of magnetization of such an amorphous metal piece is sharply reversed when it is subjected to an alternating magnetic field, when this magnetization reversal is detected by a detection coil or the like, the detection output becomes an output containing many high-frequency components. A signal is obtained. Therefore, by detecting the presence or absence of a high-frequency component in the output signal, it is possible to detect the presence or absence of the amorphous metal piece in the alternating magnetic field.

The above-mentioned amorphous metal piece is attached to an article such as a book or clothing packaging as an identification mark, and an alternating magnetic field generation region is provided at a predetermined place such as an exit of a building to provide an identification mark. By issuing an alarm when the attached article passes through the generation area, the article can be prevented from being stolen.

[0005] Further, by using the above-mentioned amorphous metal piece as an identification mark indicating the characteristic of the article, the characteristic of the article can be detected in a non-contact state, and the identification mark can be used for distribution management of the article. Can be used.

[0006]

However, the above-mentioned amorphous metal piece has a low saturation magnetic flux density and a small output voltage induced in the detection coil due to the magnetization reversal. Therefore, to accurately detect the presence or absence of magnetization reversal,
It is necessary to take measures to increase the output voltage, such as increasing the number of turns of the detection coil, increasing the cross-sectional area and length of the amorphous metal piece, or reducing noise.

For example, in order to obtain a required output level, it is necessary to form an amorphous metal wire having a diameter of about 100 μm or more. Further, if the length of the amorphous metal wire is not formed to be at least about 800 times the wire diameter, sharp magnetization reversal does not occur, so that the length is necessarily 100 mm or more. In this case, there is a problem that the amorphous metal wire is too large to be used as an identification mark of an article.

If the number of windings of the detecting coil is increased or a measure for reducing noise is taken to obtain a required output level, the size of the detecting device becomes large and the manufacturing cost increases. .

The present invention has been made in view of the above points, and an object of the present invention is to provide an identification mark and an anti-theft system that can be accurately detected without increasing the size and the manufacturing cost.

[0010]

In order to achieve the above object, the identification mark according to the present invention has a Si concentration of 2.5 to 2.5.
Fe-S with 3.5 wt% and Mo concentration of 3.5-4.5 wt%
It is provided with a metal piece formed of an i-Mo alloy and having a sharp magnetization reversal when an alternating magnetic field exceeding its coercive force is applied.

The metal piece is formed in a linear shape and has a wire diameter of 30.
The length is formed to 300 to 500 times the wire diameter. The antitheft system according to the present invention has a Si concentration of 2.5 to 3.5 wt% and a Mo concentration of 3.5.
A metal piece which is made of an Fe-Si-Mo alloy of about 4.5 wt% and which generates a sharp magnetization reversal when an alternating magnetic field exceeding its coercive force is applied; A detection device that determines the presence or absence of the anti-theft sign for an article passing through a predetermined inspection area, and issues an alarm when the presence of the anti-theft sign is detected.

[0012] The detection device includes a magnetic field application unit that applies an alternating magnetic field having a strength exceeding the coercive force of the metal piece to the inspection region, a reception unit that outputs a change in the magnetic field in the inspection region as an output signal, Detecting means for detecting, from the output signal, a pulsed output resulting from the magnetization reversal of the metal piece; comparing means for comparing the detected pulsed output with reference data prepared in advance; Alarm means for issuing an alarm when the data matches the reference data.

[0013]

The metal piece of the identification mark constructed as described above is
When an alternating magnetic field having an amplitude larger than the coercive force is received, a sharp magnetization reversal occurs due to a large Barkhausen effect. By detecting the change in the magnetic field accompanying the magnetization reversal by a receiving means such as an electromagnetic induction coil, a pulse-like output is detected. The magnetization reversal hardly depends on the frequency of the applied alternating magnetic field, and the same pulse output can be obtained even when the frequency of the alternating magnetic field is low. By comparing this pulsed output with predetermined reference data or the like, the presence or absence of an identification mark,
The type and the like can be determined.

When the identification mark is attached to an article and used as an anti-theft sign, when the article passes through a predetermined inspection area, the presence or absence of the anti-theft sign is detected by a detection device, and the presence of the anti-theft sign is detected. Raises an alarm if it is done.

In the detection of the anti-theft sign, the detecting device applies an alternating magnetic field having a strength exceeding the coercive force of the metal piece to the inspection area by the magnetic field applying means, and detects the magnetic field in the inspection area by the receiving means such as the detection coil. Convert the change to an output signal. Since this output signal includes a low-frequency output signal corresponding to the alternating magnetic field applied by the magnetic field applying means, by removing this low-frequency output signal with a low-pass filter or the like, the high-frequency output associated with the magnetization reversal is removed. Is detected. Then, the detected pulse output is compared with predetermined reference data by the comparing means, and when they match, the existence of the anti-theft sign is determined and an alarm is issued by the alarm means.

The administrator of the detecting device can detect that the article with the anti-theft sign is passing through the inspection area by the alarm, and can prevent the article from being stolen beforehand.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1 and 2 show an embodiment of an anti-theft system using an identification mark according to the present invention. FIG. 1 shows an identification mark 10 as an anti-theft sign attached to a box-shaped article. Also, in FIG.
Each of the detection devices 20 for detecting the identification mark is shown.

As shown in FIG. 1, the identification mark 10 has an elongated metal wire 12 as a metal piece. This metal wire 12 has a Si concentration of 2.5 to 3.5 wt%, a Mo concentration of 3.5 to 4.5 wt%, a wire diameter of 30 to 125 μm, and a length of about 200 to 600 times the wire diameter, preferably. 300-500
It is composed of a Fe-Si-Mo single crystal alloy wire formed about twice as large. The cross-sectional shape of the metal wire 12 is preferably a circle, but may have an irregular cross-section such as an ellipse or a polygon. The metal wire 12 has a saturation magnetic flux density of about 1.2 to 2.0 times that of the amorphous metal wire.

The metal wire 12 has a strong magnetic anisotropy in the axial direction due to a magnetic effect due to its shape and crystal structure. Therefore, when the metal wire 12 receives an alternating magnetic field having an amplitude larger than its coercive force (for example, 0.1 to 1.0 Oe), a very steep magnetization reversal occurs due to a large Barkhausen effect.

When this magnetization reversal is detected by, for example, a solenoid coil, a pulse-like output as shown in FIG. 3 is obtained. That is, in FIG. 3, when the positive coercive force of the metal wire 12 is Hp and the negative coercive force is −Hp, when the alternating magnetic field exceeds these coercive forces Hp and −Hp, the metal wire 1
2 is generated, and a pulse output voltage corresponding to the magnetic reversal is detected. The width of this pulse is 10-10
Since the output voltage is very small at 0 μsec, the output voltage contains many high-frequency components of several KHz or more. The magnetization reversal is
Almost no dependence on the frequency of the applied alternating magnetic field, and even when the frequency is low, the same pulse output can be obtained.

The above-mentioned pulse output voltage obtained when an alternating magnetic field is applied to the metal wire 12 varies depending on the length of the metal wire with respect to the wire diameter, the Si concentration (wt%), and the Mo concentration (wt%). I do. FIG. 4 shows the measurement results obtained by measuring the relationship between the length / wire diameter ratio and the output voltage with respect to the metal wire 12 of this example made of an Fe—Si—Mo alloy and the metal wire made of an amorphous alloy. I have. The measurement was performed in a state where an alternating magnetic field having an exciting magnetic field of ± 1.5 Oe and an exciting frequency of 50 Hz was applied to a metal wire having a wire diameter of 90 μm disposed in a 200-winding / 5 mm detecting coil.

As can be seen from FIG. 4, Fe--Si--Mo
The metal wire 12 of the present embodiment made of an alloy has a length of 3 mm in diameter.
If it is 00 times or more, it is possible to obtain a larger and sufficient output voltage than the metal wire of the amorphous alloy. For example, in the case of a metal wire having a wire diameter of 30 to 125 μm, if the length exceeds 500 times the wire diameter, the wire becomes large and impractical.
It is desirable to set the range to 0 times.

FIG. 5 shows that Fe under the same measurement conditions as above.
The measurement result which measured the relationship between Mo density | concentration and output voltage regarding the metal wire 12 of this Example which consists of -Si-Mo alloy is shown. The measurement was performed with the Si concentration fixed at 3 wt%. As can be seen from this figure, the Mo concentration was about 3.5.
By setting the amount within the range of 4.5 wt%, a sufficient output voltage can be obtained.

FIG. 6 shows a metal wire 1 of this embodiment made of an Fe—Si—Mo alloy under the same measurement conditions as described above.
2 shows the measurement results obtained by measuring the relationship between the Si concentration and the output voltage for No. 2. The measurement was performed with the Mo concentration fixed at 4 wt%. As can be seen from this figure, by setting the Si concentration within the range of about 2.5 to 3.5 wt%,
A sufficient output voltage can be obtained.

As shown in FIG. 1, such a metal wire 12 is fixed to a label 14 having an adhesive applied to the back surface.
This label is attached to the article 16 by attaching it to an arbitrary portion of the article 16. As shown in FIG. 7, a metal wire 12 is attached to a label 14 on which a barcode is printed.
May be fixed in advance, and in this case, it is possible to omit the label dedicated to the metal wire. Here, since the metal wire 12 is very thin and flexible, it can be easily attached not only to an article having a flat surface but also to an article having a curved surface such as a bottle or a can.

Further, the present invention is not limited to the label, and the metal wire 12 may be fixed to a tag such as a tag or a price tag, and the tag may be detachably attached to the article. On the other hand, as shown in FIG. 2, a detection device 20 that detects the identification mark 10 provided with the metal wire 12 includes a transmitter 24 that functions as a magnetic field application unit that generates an alternating magnetic field in an inspection area 22 through which the article 16 passes. And a receiver 26 for detecting a change in the magnetic field in the inspection area 11.

The transmitter 24 has a transmitting coil 27 and an AC generator 30 for supplying an alternating current to the transmitting coil via an amplifier 28. And the transmitting coil 27
Generates an alternating magnetic field corresponding to the alternating current supplied from the AC generator 30 via the amplifier 28, and applies the alternating magnetic field to the inspection area 22.

The receiver 26 includes a detection coil 32 functioning as an electromagnetic induction coil and a detection circuit 34 connected to the detection coil. The detection coil 32 is disposed at an interval enough for a person to pass through, for example, at an interval of 1 m.
7 and the inspection area 22 between the transmitting coil 27
Is formed. Then, a current corresponding to the magnetic field in the inspection region 22 is induced in the detection coil 32 constituting the receiving unit, and this current is output to the detection circuit 34 as an output signal.

The detection circuit 34 includes a low-pass filter 36, an amplifier 38, and a comparator 40 which are sequentially connected to the transmission coil 32. The low-pass filter 36 constitutes a detecting means, and cuts a low-frequency output signal corresponding to an alternating magnetic field generated by the transmitter 24 from among the output signals from the detection coil 32, to perform the magnetization reversal of the identification marker 10. Only the output signal of the high frequency component accompanied by the resulting pulse output is extracted. Since the pulse output includes a high frequency component, it is extracted without being attenuated by the low-pass filter 32. Further, since the pulse-shaped output is periodically output each time the polarity of the alternating magnetic field changes, the pulse-shaped output is detected almost instantaneously without relatively moving the article 16 with the identification mark 10 relative to the alternating magnetic field. You.

The comparator 33 functioning as a comparing means compares the detected pulse-shaped output with reference data prepared in advance, thereby collating the identification mark 10. An alarm device 44 is connected to the comparator 40 via a drive unit 42. The drive section 42 activates the alarm device 44 in accordance with the result of the comparison by the comparator 40, and the alarm device notifies the third person of the result of the comparison by, for example, a display means such as an indicator light or a notification sound.

The detection device 20 having such a configuration is installed at, for example, an exit of a building and monitors articles passing through the inspection area 22 to prevent theft. That is,
Usually, the transmitter 24 generates an alternating magnetic field larger than the coercive force of the metal wire 12 of the identification mark 10 in the inspection area 22, and the receiver 26 constantly monitors the magnetic field change in the inspection area 22.

As shown in FIG. 2, when the person carrying the article 16 with the identification mark 10 passes through the inspection area 22,
A pulse-like output is detected by the receiver 26 and the comparator 4
0 is compared with the reference data corresponding to the identification mark 10. As a result of the collation, when the detected pulse-shaped output matches the reference data, the detection circuit 34 determines that the identification mark 10 attached to the article 16 is an anti-theft sign, and Activate the alarm device 44. Therefore,
The administrator of the inspection area 22 can recognize from the alarm from the alarm device 44 that the article 16 is a stolen product, and can prevent theft before it occurs.

According to the identification mark 10 configured as described above, since the metal wire 12 is formed of the Fe-Si-Mo alloy, its saturation magnetic flux density is lower than that of the metal wire formed of the amorphous alloy. 1.2-2.0 times larger compared to
If the cross-sectional area is the same as that of the amorphous alloy wire, the level of the pulse output detected due to the magnetization reversal also increases. Therefore, by setting the length of the metal wire 12 to about 300 to 500 times the wire diameter, a sufficient detection output can be obtained, and as a result, an identification marker that can be accurately recognized without increasing the size is obtained. Obtainable. Further, since the detection output is large, the S / N ratio is also improved, and more accurate recognition is possible.

When the detection output of the metal wire 12 is set to be equal to that of the amorphous alloy wire, the wire diameter can be made smaller than that of the amorphous alloy wire, and the length can be made shorter. Therefore, the size of the identification mark can be reduced.

Further, since the detection output is increased, accurate detection is possible even when the number of turns of the detection coil 32 of the detection device 20 for detecting the presence or absence of the identification mark is reduced. As a result, the detection device and the anti-theft system The overall size and cost can be reduced.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, since the identification mark according to the present invention can detect the passage of an article in a non-contact state, the above-described product,
The present invention can be applied not only to the prevention of theft of articles such as important documents and books, but also to the distribution management of cargo.

When an identification sign is used for the distribution management of such a cargo, as shown in FIG. 8, an identification sign 10 having the same configuration as that of the above embodiment is provided on the surface or inside of the cargo 50, and The transmitting coil 27 and the detecting coil 32 of the detecting device 20 are provided on both sides of the transport path 52. Then, the pulse output based on the identification mark 10 attached to the cargo 50 passing between the transmitting coil 27 and the detection coil 32 is detected, and the cargo 50 is identified. As a result of the identification, for example, when the predetermined identification mark 10 is detected, the driving unit 42
By operating the sorting mechanism 54 via the interface, the transport path 52 can be switched and the cargo 50 can be automatically sorted.

[0038]

As described in detail above, according to the present invention,
A large pulse-shaped output having a high S / N ratio can be obtained,
A small identification mark capable of accurate identification can be provided. Accordingly, the size and cost of the detection device for detecting the identification mark can be reduced, and the size and cost of the entire anti-theft system can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an article provided with an identification mark according to one embodiment of the present invention.

FIG. 2 is a perspective view showing the entirety of an anti-theft system using the identification sign as an anti-theft sign.

FIG. 3 is a diagram showing a relationship between an excitation magnetic field of a metal wire of the identification mark and an output.

FIG. 4 is a diagram showing the relationship between the length / wire diameter ratio of the metal wire and the output voltage in comparison with an amorphous metal wire.

FIG. 5 is a diagram showing a relationship between the Mo concentration of the metal wire and an output voltage.

FIG. 6 is a view showing the relationship between the Si concentration of the metal wire and the output voltage.

FIG. 7 is a plan view showing an embodiment in which an identification mark according to the present invention is combined with a barcode label.

FIG. 8 is a perspective view schematically showing an embodiment in which the identification mark according to the present invention is applied to distribution management of cargo.

[Explanation of symbols]

10: identification sign, 12: metal wire, 20: detection device,
22 ... inspection area 24 ... transmitter, 26 ... receiver, 34 ... detection circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-60095 (JP, A) JP-A-7-92909 (JP, A) JP-A-1-131995 (JP, A) JP-A-55-1990 143695 (JP, A) JP-A-58-39396 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08B 13/24 C22C 38/00 303 C22C 38/12

Claims (5)

(57) [Claims] 1. An Fe-Si-Mo alloy having a Si concentration of 2.5 to 3.5 wt% and a Mo concentration of 3.5 to 4.5 wt%, and an alternating magnetic field exceeding its coercive force is applied. An identification marker with a metal piece that causes a sharp magnetization reversal at the time. 2. An Fe--Si--Mo alloy having a Si concentration of 2.5 to 3.5 wt% and a Mo concentration of 3.5 to 4.5 wt%, and an alternating magnetic field exceeding its coercive force is applied. A metal wire that causes a steep magnetization reversal when the metal wire has a wire diameter of 30 to 125 μm and a length of 300 to 125 μm.
Identification mark formed 500 times. 3. An Fe--Si--Mo alloy having a Si concentration of 2.5 to 3.5 wt% and a Mo concentration of 3.5 to 4.5 wt%, and an alternating magnetic field exceeding its coercive force is applied. In the case of the theft prevention sign attached to the article equipped with a metal piece that causes a sharp magnetization reversal at the time, the presence or absence of the above-mentioned anti-theft sign for the article passing through the predetermined inspection area is determined, A detection device that issues an alarm when detected. 4. The metal piece has a wire diameter of 30 to 125 μm.
The anti-theft system according to claim 3, wherein the anti-theft system is formed in an elongated shape having a length of 300 to 500 times the wire diameter. 5. The detection device according to claim 1, wherein the detection device applies an alternating magnetic field having a strength exceeding the coercive force of the metal piece to the inspection region, and a reception device that outputs a change in the magnetic field in the inspection region as an output signal. Means, detecting means for detecting a pulse output generated from the output signal due to the magnetization reversal of the metal piece, comparing means for comparing the detected pulse output with reference data prepared in advance, 4. The anti-theft system according to claim 3, further comprising: an alarm unit that issues an alarm when a pulse output matches the reference data.