JP3255221B2 - Anti-theft tag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tag for notifying unauthorized removal of an article to be monitored for theft.

[0002]

2. Description of the Related Art Conventionally, as this kind of anti-theft tag,
The resonance circuit part of the tag attached to the theft monitoring article resonates with the radio wave of a specific frequency from the radio wave transmitting device, and the separation detecting means detects whether the tag has been separated from the theft monitoring article and separates the tag. An anti-theft tag is disclosed in which a separation notification unit controls a notification sound output unit based on a detection output of a detection unit (Japanese Patent Application Laid-Open No. 8-185584).
In this anti-theft tag, the resonance circuit portion is formed by forming a conductive metal foil of a predetermined shape on both surfaces of an insulating dielectric thin film by etching or the like. For example, an induction circuit portion formed in a spiral shape by a conductive metal foil on the surface of a thin film, and a surface-side planar pattern of a capacitor circuit portion continuous with the induction circuit portion is formed at the spiral center of the induction circuit portion. Is done. The separation detection means is a removal detection switch having an operation bar protruding from a surface of the tag attached to the article, and a power supply and a buzzer are electrically connected to the detection switch.
A circuit constituted by the detachment detection switch, the power supply and the buzzer is a separation notification unit, and the buzzer is a notification sound output unit. When the tag is attached to the article, the operation bar is pushed by the article and the removal detection switch is turned off, and when the tag is removed from the article, the operation bar is projected and the removal detection switch is turned on.

At the entrance of a store selling the theft monitoring article, a transmitting antenna and a receiving antenna are erected at a predetermined interval from each other, and these antennas are electrically connected to a control unit. The control unit causes the transmission antenna to transmit a radio wave having a frequency that resonates in the resonance circuit unit,
The signal level of the received signal from the receiving antenna is always checked. Further, a speaker for issuing an alarm is connected to the control output of the control unit. In the anti-theft tag configured as described above, when an article monitored for theft attempts to pass between the transmitting antenna and the receiving antenna without being cleared, the radio wave transmitted from the transmitting antenna is transmitted to the anti-theft article. Since the signal is resonated by the resonance circuit of the attached tag, a reception signal whose reception level is modulated is received by the reception antenna. As a result, the control unit issues an alarm from the speaker and can check the removal of uncleared goods. When the tag is removed from the article, the operation bar protrudes and the removal detection switch is turned on, so that the buzzer sounds and the theft can be monitored reliably.

[0004]

However, in the above-mentioned conventional anti-theft tag, when the tag is attached to an article whose surface is formed of a conductive material such as aluminum or a ferromagnetic material such as a steel plate, the resonance circuit portion is not provided. Since the self-inductance changes, the resonance frequency of the resonance circuit changes compared to when the tag is attached to an article whose surface is made of an insulating or non-magnetic material, making it unsuitable as an anti-theft tag Met. An object of the present invention is to provide an anti-theft tag in which the resonance frequency of the resonance circuit section does not change even if the surface of the theft monitoring article is formed of any material.

[0005]

The invention according to claim 1 is
As shown in FIGS. 1 and 3, this is an improvement of the anti-theft tag 12 provided with a resonance circuit section 14 attached to the theft monitoring article 11 and resonating with a radio wave of a specific frequency transmitted from the transmission antenna 13. The characteristic configuration is that a flake of a soft magnetic material is provided between the mounting surface of the article 11 and the resonance circuit portion 14.
Soft magnetic layer 16 formed of a composite material with plastic
There is where interposed. In the anti-theft tag according to the first aspect, when the resonance circuit portion 14 is attached via the soft magnetic layer 16 to the article 11 whose surface is formed of a conductive material such as aluminum or a ferromagnetic material such as a steel plate, resonance occurs. Since the circuit section 14 is electromagnetically shielded from the article 11 by the soft magnetic layer 16, the self-inductance of the resonance circuit section 14 is almost the same as that when the circuit section is attached to an article whose surface is formed of an insulating material or a non-magnetic material. The invention according to claim 2 is the invention according to claim 1, wherein the thickness of the flakes of the soft magnetic material is
Is 20 μm or less.

In the anti-theft tag according to claim 2,
The thickness of the soft magnetic material flakes in the composite material is 20 μm
The frequency of the radio wave transmitted from the transmitting antenna
Suppresses eddy currents in the soft magnetic layer even at high wave numbers
Self-inductance of the resonance circuit
Does not change.

[0007] The invention according to claim 3 is based on claim 1 or 2.
Such invention, wherein the soft magnetic material further forms a soft magnetic layer
Is amorphous alloy, permalloy, soft magnetic iron, silicon steel
Plate, sendust alloy, Fe-Al alloy or soft magnetic ferrule
It is one of the sites. amorphous
Alloys such as cobalt-based, iron-based and nickel-based
A magnetic susceptibility material is used. Amorphous alloys are Co, F
e, Ni total 70-98 wt%, B, Si, P total
2-30% by weight, other Al, Mn, Zr, Nb, etc.
including.

[0008] As a specific example of the cobalt alloy, Co
-84% by weight, Fe-5.3% by weight and Si-8.5% by weight
% And B-2.2% by weight, Co-84% by weight
And Fe-3.3% by weight, B-1.3% by weight and P-9.8.
% Alloy with Al-1.6% by weight, Co-89
Wt%, Fe-5.3 wt%, Si-2.3 wt%, and B
Alloy consisting of -3.4% by weight, Co-81.9% by weight
Fe-5.1% by weight, Si-10% by weight and B-3% by weight
Alloy consisting of 80% by weight of Co and 10% by weight of Fe
Alloy composed of Si-6% by weight and B-4% by weight, Co-7
8.8% by weight, Fe-5.1% by weight and Si-6.1% by weight
%, B-4.7% by weight and Ni-5.3% by weight.
There are gold etc. A specific example of an iron-based alloy is Fe-9
An alloy consisting of 5.4% by weight and B-4.6% by weight, Fe-
91.4% by weight, Si-5.9% by weight and B-2.7% by weight
% Alloy. Specific examples of Ni-based alloys
Consists of Ni-94.5% by weight and P-5.5% by weight
Alloys and the like.

As the permalloy, 78-Permalloy, 45-P
ermalloy, Hipernik, Monimax, Sinimax, Radiometal,
1040 Alloy, Mumetal, Cr-Permalloy, Mo-Permalloy, S
upermalloy, Hardperm, 36-Permalloy, Deltamax, square
Hysteresis permalloy, JIS PB class 1 and 2, JIS PC
1 to 3 types, JIS PD 1 and 2 types, JIS PE 1 and 2 types
Used. As electromagnetic soft iron, industrial pure iron, armco
Iron, Cioffi pure iron, low carbon steel plate, etc. are used. Silicon steel
Non-oriented silicon steel sheet, oriented silicon steel sheet, etc.
Is used. As Sendust Fe-Al alloy,
Alpalm, Hyper Mar, Sendust, Super Sen
Dust or the like is used. Low for soft magnetic ferrite
Magnetic flux density of Mn-Mg based alloy, Mn-Zn based alloy, Ni
-Uses Zn-based alloys and Mn-Zn-based alloys with high magnetic flux density
Can be. In the anti-theft tag according to claim 2, the tag is soft.
When the above soft magnetic material is used for the magnetic layer, the magnetic permeability becomes 10
00 or more and coercive force as small as 100 A / m or less
Surface with low hysteresis loss.
Resonance circuit from articles made of conductive or ferromagnetic materials
Electromagnetic shielding of the part can be ensured.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIGS. 1 to 3, the tag 12 attached to the theft monitoring article 11 has a resonance circuit section 14 that resonates with a radio wave of a specific frequency transmitted from the transmission antenna 13 and a resonance circuit section 14 that resonates with the mounting surface of the article 11. A soft magnetic layer 16 interposed between the circuit section 14 and the circuit section 14. The article 11 is a container 11 made of a steel plate which is a ferromagnetic material in this embodiment.
a, drinking water, edible oil, candy, etc.
The resonance circuit section 14 includes a base plate 17 formed of an insulating material such as paper or a plastic thin plate, and a coil formed on one surface of the base plate 17 in a substantially square spiral shape by a conductive material such as copper or aluminum. Part 18 and base plate 17
(See FIGS. 1 and 2), which is adhered to one surface of the coil and electrically connected to the coil portion 18. The capacitor 19 includes a pair of electrode layers 19a bonded to each other via a dielectric layer (not shown). The coil portion 18 is formed by spirally winding an insulated conducting wire into a substantially square shape and attaching it to the base plate 17, or by etching or punching a conductive material such as aluminum foil or copper foil laminated on the base plate 17. Unnecessary portions are removed by, for example, forming a substantially square spiral shape.

The soft magnetic layer 16 is made of an amorphous alloy, permalloy, electromagnetic soft iron, silicon steel plate, sendust alloy, F
It is formed of a soft magnetic material such as an e-Al alloy or a soft magnetic ferrite. The soft magnetic layer 16 is formed in a flat plate shape having substantially the same area as the base plate 17, and is adhered by an adhesive 21 to one surface of the base plate 17 on which the coil portion 18 and the capacitor 19 are formed. The soft magnetic layer 16 adhered to the base plate 17 is bonded to the article 1 via an adhesive 22.
1, that is, on the surface of a steel plate container 11a (FIGS. 1 to 3). The transmitting antenna 13 and the receiving antenna 23 are erected at a predetermined distance from an entrance (not shown) of a store that sells the article 11 (FIG. 3). The receiving antenna 23 is connected to a control input of the control unit 24, and the transmitting antenna 13 is connected to a control output of the control unit 24. A speaker 26 that issues an alarm is connected to the control output of the control unit 24.

The control unit 24 is configured to cause the transmission antenna 13 to transmit a radio wave having a frequency that resonates in the resonance circuit unit 14 and to always check the signal level of the reception signal from the reception antenna 23. That is, the signal level when the radio wave transmitted from the transmission antenna 13 is directly received by the reception antenna 23 is set as a reference value, and the transmission antenna 13
When the receiving antenna 23 receives the radio wave transmitted from the tag 12 and resonates in the resonance circuit section 14 of the tag 12, the signal level becomes higher than the reference value by a predetermined value. At this time, the control section 24 makes the speaker 26 sound. It is configured as follows.

The operation of the anti-theft tag configured as described above will be described. When the article 11 to which the tag 12 is attached passes from the transmitting antenna 13 and the receiving antenna 23 in order to take it out of the store without permission, the resonance circuit section 14 of the tag 12 picks up the radio wave transmitted from the transmitting antenna 13 and resonates. Wake up. At this time, since the resonance circuit section 14 is electromagnetically shielded from the steel plate container 11a of the article 11 by the soft magnetic layer 16, the self-inductance of the resonance circuit section 14 hardly changes. As a result, a radio wave having a predetermined frequency based on the self-inductance of the coil unit 18 and the capacitance of the capacitor 19 is re-emitted from the resonance circuit unit 14. When the receiving antenna 23 receives the re-radiated radio wave, the control unit 24, based on the received signal, controls the article 11 for which the fee has not been paid.
Is detected to be taken out without permission.
Sounds an alarm. On the other hand, when the fee is paid regularly, a strong radio wave is radiated to the tag 12 at an accounting place (not shown), and the capacitor 19 of the resonance circuit unit 14 is destroyed. As a result, the transmitting antenna 13 and the receiving antenna 23
Even when the article 11 passes through the space, the resonance circuit 14 does not resonate, so the control unit 24 does not sound the speaker 26.

In this embodiment, drinking water, edible oil and candy contained in a container made of a steel plate which is a ferromagnetic material are described as the articles. However, it is contained in an aluminum container which is a conductive material. It may be drinking water or the like, or an article formed of an insulating material, a non-magnetic material, or any other material. If the article is a book, the tag of the present invention can be attached to the sales card with an adhesive, and the book purchased properly can be removed at the checkout place of the store, so that the transmitting antenna and the receiving antenna can be used. The loudspeaker does not give an alarm when passing through. Further, in this embodiment, the coil portion is formed in a substantially square spiral shape, but may be formed in a substantially circular spiral shape or another type of spiral shape. Also, in this embodiment,
Although the soft magnetic layer is attached to the surface of the article via an adhesive, it may be attached to the surface of the article via an adhesive tape coated on both sides with an adhesive. The thickness of the soft magnetic layer is not particularly limited as long as the electromagnetic shielding effect is exhibited.
It is preferably in the range of m to 500 μm. Further, the soft magnetic layer can be formed of a composite material of flakes of soft magnetic material and plastic. In this case, in order to prevent eddy currents from being generated in the flakes, it is preferable that the thickness of the flakes of the soft magnetic material be set to 20 μm or less. As the plastic, it is preferable to use acrylic resin, polyester, polyvinyl chloride, polyethylene, polystyrene, epoxy, or the like having an insulating property.

[0015]

Next, examples of the present invention will be described in detail together with comparative examples. <Embodiment 1> As shown in FIGS. 1 and 2, the base plate 17 of the resonance circuit portion 14 of the tag 12 attached to the article 11 is made of an insulating material such as paper having a length, width and thickness of 40.
The coil portion 18 is formed in a plate shape of mm, 40 mm, and 0.1 mm, and is formed by winding an insulated conductive wire having a diameter of 0.2 mm on one surface of the base plate 17 nine times in a substantially square spiral shape.
Was pasted. The length of the outermost side of the coil portion 18 was 30 mm, and the length of the innermost side was 10 mm. However, the capacitor 19 shown in FIG. 2 was not connected to both ends of the coil unit 18. This is because the resonance frequency of the resonance circuit section 14 changes depending on the material of the article 11 because the self inductance of the coil section 18 changes, and the capacitance of the capacitor 19 does not change even when the material of the article 11 changes. is there. Further, the soft magnetic layer 16 was bonded to one surface of the base plate 17 with the coil portion 18 interposed therebetween. The soft magnetic layer 16 is composed of 80% by weight of Co, 10% by weight of Fe and 6% by weight.
, 40 mm, 40 mm, and 25 μm in thickness, width, and thickness, respectively, using an alloy of Si and 4% by weight of B. This tag 12 was Example 1.

<Embodiment 2> Although not shown, the soft magnetic layer is made of a composite material of flakes of a cobalt-based amorphous alloy and an acrylic resin to have a length, width and thickness of 40 mm and 4 mm, respectively.
A tag was formed in the same manner as in Example 1 except that the tag was formed at 0 mm and 0.6 mm. The cobalt-based amorphous alloy is composed of 80% by weight of Co, 10% by weight of Fe,
An alloy consisting of 4% by weight of Si and 4% by weight of B. The flakes of this alloy ranged in diameter from 0.05 mm to 0.5 mm and in thickness from 5 μm to 50 μm. This tag was designated as Example 2. <Embodiment 3> Although not shown, the length, width and thickness of the soft magnetic layer were made of permalloy of 40 mm, 40 mm and 0.1 mm, respectively.
A tag was formed in the same manner as in Example 1 except that the tag was formed to be 05 mm. The permalloy is a JIS PC. <Comparative Example 1> A tag was formed in the same manner as in Example 1 except that a soft magnetic layer was not used, although not shown.

<Comparative Test and Evaluation> The tags of Examples 1 to 3 and Comparative Example 1 were placed on an acrylic plate (thickness 1 mm), an aluminum plate (thickness 1 mm) and a steel plate (thickness 1 mm), respectively. Insert the tag coil into the RF
Impedance analyzer HP 4191A (Yokogawa Hyu
Connect to the Retto-Packard Co., Ltd.), by changing the frequency
Was boss measure the self-inductance of the coils portion. Table 1 shows the results.

[0018]

[Table 1]

As is clear from Table 1, when the tag of Comparative Example 1 was placed on an aluminum plate or a steel plate, the self-inductance for each frequency of the radio wave was greater than when the tag of Comparative Example 1 was placed on an acrylic plate. However, when the tags of Examples 1 to 3 were placed on any of an acrylic plate, an aluminum plate, and a steel plate, the self-inductance for each frequency of the radio wave hardly changed. As a result, Examples 1 to
With the tag No. 3, it was found that the resonance frequency for each frequency of the radio wave was substantially constant, regardless of the material to which the tag was attached.

[0020]

As described above, according to the present invention, the anti-theft tag attached to the theft monitoring article has the resonance circuit portion which resonates with the radio wave of the specific frequency transmitted from the transmitting antenna. Since the soft magnetic layer formed of a soft magnetic material is interposed between the mounting surface of the article and the resonance circuit portion, the surface of the resonance circuit portion is formed of a conductive material or a ferromagnetic material by the soft magnetic layer. In addition, since the above-mentioned article is electromagnetically shielded, the self-inductance of the resonance circuit portion hardly changes. That is,
The resonance frequency of the resonance circuit unit attached to the article is substantially the same as that when the article is attached to an article whose surface is formed of an insulating material or a non-magnetic material.

If the soft magnetic material forming the soft magnetic layer is any of an amorphous alloy, permalloy, electromagnetic soft iron, silicon steel sheet, sendust alloy, Fe-Al alloy or soft magnetic ferrite, these soft magnetic materials are transparent. Since the magnetic susceptibility is large, the coercive force is small, and the hysteresis loss is small, the resonance circuit portion can be reliably electromagnetically shielded from an article whose surface is formed of a conductive material or a ferromagnetic material. Furthermore, if the soft magnetic layer is a composite material of flakes of soft magnetic material and plastic, even if the frequency of the radio wave transmitted from the transmitting antenna is high, generation of eddy currents in the soft magnetic layer is suppressed. Has almost no change in self inductance. That is, the resonance frequency of the resonance circuit unit attached to an article whose surface is formed of a conductive material or a ferromagnetic material is substantially the same as that of a case where the surface is attached to an article whose surface is formed of an insulating material or a non-magnetic material. .

[Brief description of the drawings]

FIG. 1 shows an anti-theft tag according to an embodiment of the present invention.
Sectional view on the AA line of FIG.

FIG. 2 is a sectional view taken along line BB of FIG. 1;

FIG. 3 is a diagram showing a state in which an article to which the tag is attached is passed between a transmitting antenna and a receiving antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Article 12 Tag 13 Transmission antenna 14 Resonant circuit part 16 Soft magnetic layer

Continuation of the front page (56) References JP-A-8-222937 (JP, A) JP-A-59-182791 (JP, U) JP-B-7-82592 (JP, B2) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G08B 13/24

Claims (3)

(57) [Claims] An anti-theft tag (12) provided with a resonance circuit (14) attached to a theft monitoring article (11) and resonating with a radio wave of a specific frequency transmitted from a transmission antenna (13), Soft between the mounting surface of the article (11) and the resonance circuit section (14)
An anti-theft tag comprising a soft magnetic layer (16) formed of a composite material of a flake of a magnetic material and a plastic . 2. The flake thickness of the soft magnetic material is 20 μm.
The anti-theft tag according to claim 1, wherein 3. A soft magnetic material is amorphous alloy forming a soft magnetic layer, permalloy, electromagnetic soft iron, silicon steel, sendust alloy, Fe-Al alloy or theft of claim 1 or 2, wherein either of the soft ferrite Prevention tag.