Acoustic-magnetic Anti-theft label

Abstract

Disclosed in the present invention is an acoustic-magnetic anti-theft label, wherein in the acoustic-magnetic anti-theft label, a wire-shaped bias element which is made by means of a low-cost metal wire cold-drawing process is used. Compared with sheet-shaped bias elements in the prior art which are made by means of a cold-rolling process, the bias wire in the present invention has better hysteresis loop squareness due to sufficient shape anisotropy being produced after large deformation of a wire-shaped structure of the bias wire in an axial direction, such that the magnetic flux of the bias wire in the axial direction is stable. Moreover, there is a small change in the cross-sectional area of a wire material relative to that of a cold-rolled steel strip, such that a bias element which is formed by means of magnetizing the wire material has a small fluctuation in terms of magnetic flux; therefore, an acoustic-magnetic label in which a wire material is biased has a good alarm performance, a good batch activation performance and an efficient deactivation performance. By means of directly cold-drawing a low-cost material not containing (or containing a relatively low content of) Co or Ni by using a large amount of deformation to obtain a bias wire with a final cross-sectional area of 0.03-0.79 mm2, and cutting the bias wire into sections to serve as bias wire elements of acoustic-magnetic labels, an unexpectedly good alarm effect is produced.

Description

Acousto-magnetic anti-theft tag Technical Field

[0001] The present invention relates to the technical field of acousto-magnetic anti-theft technology, in particular to an acousto-magnetic anti-theft tag. Background Art

[0002] Acoustomagnetic technology has been widely used in electronic object surveillance and anti-theft devices for about 30 years. The specific working principle of the acoustomagnetic anti-theft system is: the transmitting antenna transmits an alternating magnetic field. When the acoustomagnetic anti-theft tag enters the alternating magnetic field (detection area), and the resonant frequency of the acoustomagnetic anti-theft tag is consistent with the carrier frequency in the alternating magnetic field, due to the magneto-elastic resonance effect, the resonant plate in the acoustomagnetic anti-theft tag will generate a resonance signal under the action of the magnetic field provided by the bias plate and be received by the receiving antenna, thereby detecting the presence of the acoustomagnetic anti-theft tag. The acoustomagnetic anti-theft system generally consists of two parts: one is a detector including a transmitting antenna and a receiving antenna, which uses the transmitting antenna to emit an alternating magnetic field to form a detection sensing area between the transmitting antenna and the receiving antenna, and uses the principle of magneto-elastic resonance to search for the presence of acoustomagnetic anti-theft tags within a specific range. When the acoustomagnetic anti-theft tag appears, an alarm is triggered; the second is the acoustomagnetic anti-theft tag, which is mainly composed of a resonance plate that generates magnetomechanical resonance and a bias plate that provides a bias magnetic field, which is generally cut into appropriate sizes by amorphous metal thin strips. The bias magnetic field provided by the bias plate can generate a predetermined resonant frequency (generally 58kHz) in the detection area and reflect it to the receiving antenna.

[0003] However, since Anderson first invented the acoustomagnetic tag (U.S. Patent No. 4,510,489), all patented and actual decodable acoustomagnetic tags (soft tags) have used sheet-like biasing elements. The biasing elements of existing acoustomagnetic anti-theft tags all use cold-rolled metal strips (sheet-like biasing elements) with a thickness of approximately 0.05-0.08 mm. This precision machining requires a very complex process, requiring the use of large, high-precision cold rolling mills with 20 or 26 rollers, high-precision strip leveling machines (each worth tens of millions of yuan or more), and high-precision slitting machines to produce qualified semi-hard or soft magnetic biasing elements (sheet-like) for acoustomagnetic anti-theft tags. Therefore, the processing technology for sheet-like biasing elements is difficult. Furthermore, compared to the high directionality achieved through axial cold drawing, the axial texture produced by cold-rolling thin strips alone, or after heat treatment, lacks sufficient directionality. This results in some low-cost simple alloys being unable to achieve high hysteresis loop squareness along the length direction. This leads to unstable magnetic flux in the bias element of low-cost sheet-like alloys (such as high-carbon steel and Fe-based low-alloy steels (i.e., Fe-based steels with very low content of other elements), as well as other semi-hard or soft magnetic materials), reducing the detection range and alarm stability of the acoustomagnetic anti-theft tag. Existing technologies are forced to use relatively expensive alloys, such as those containing high Co and Ni content, to achieve high hysteresis loop squareness along the rolling direction through specific heat treatment after cold rolling, resulting in high cost for the bias element (sheet).

[0004] Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide an acoustomagnetic security tag whose biasing element (wire) has high shape anisotropy, resulting in good hysteresis loop squareness, which stabilizes the magnetic flux along the length of the biasing wire. Furthermore, the cross-sectional area of ​​the wire relative to the cold-rolled steel strip varies little, resulting in minimal fluctuations in the magnetic flux of the biasing element after magnetization, thereby providing excellent alarm performance for the acoustomagnetic tag. Furthermore, the amount of processing scrap for cold-drawn wire is generally lower than that for cold-rolled steel strip, reducing costs.

[0006] To achieve the above object, an embodiment of the present invention provides an acousto-magnetic anti-theft tag, comprising: a resonant plate and at least one bias wire for providing a bias magnetic field for the resonant plate; the cross-sectional area of ​​the bias wire is 0.03 to 0.79 mm 2 .

[0007] In some embodiments, the biasing wire has a length of 10-40 mm.

[0008] In some embodiments, the number of the bias wire is 1, and the length of the bias wire is 10-40 mm.

[0009] In some embodiments, the number of the bias wire is 1, and the length of the bias wire is 30-40 mm.

[0010] In some embodiments, the number of the bias wires is 2-3, and the length of each bias wire is 10-40 mm.

[0011] In some embodiments, the number of the bias wires is 2-3, and the length of each bias wire is 10-35 mm.

[0012] In some embodiments, the number of the bias wires is 2-3, and the length of each bias wire is 22-35 mm.

[0013] In some embodiments, when the length of the bias wire is greater than 30 mm, the bias wire may be curved.

[0014] In some embodiments, the bias wire is a semi-hard magnetic or soft magnetic bias wire.

[0015] In some embodiments, the DC coercivity of each bias filament is 8-55 Oe.

[0016] In some embodiments, the bias wire is made of a low-cost Fe-based alloy material.

[0017] In some embodiments, the bias wire is made of an Fe-based alloy containing no or low content of Co or Ni.

[0018] In some embodiments, the biasing wire is composed of carbon and iron.

[0019] In some embodiments, the weight percentage of carbon in the biasing filament is 0.6-1.1 wt%.

[0020] In some embodiments, the bias wire is composed of an iron-based alloy that also contains nickel.

[0021] In some embodiments, the bias wire is composed of nickel and iron.

[0022] In some embodiments, the weight percentage of nickel in the bias wire is 8-18 wt %.

[0023] In some embodiments, the bias wire is composed of an iron-based alloy that also contains nickel and at least one other transition metal.

[0024] In some embodiments, the bias wire is composed of nickel, at least one transition group metal, and iron.

[0025] In some embodiments, the weight percentage of nickel in the bias wire is 45-55 wt %, and the sum of the weight percentages of the at least one transition group metal does not exceed 5 wt %.

[0026] In some embodiments, the weight percentage of nickel in the bias wire is 8-22 wt %, and the sum of the weight percentages of the at least one transition group metal does not exceed 5 wt %.

[0027] In some embodiments, the bias wire is composed of an iron-based alloy that also contains manganese.

[0028] In some embodiments, the weight percentage of manganese in the bias wire is 8-14%, and the weight percentage of other transition metals is 0-5 wt%.

[0029] In some embodiments, the biasing wire is composed of manganese and iron.

[0030] In some embodiments, the weight percentage of Mn in the bias wire Fe—Mn alloy is 8-14 wt %.

[0031] In some embodiments, the alarm distance of the acoustomagnetic anti-theft tag in the X direction is 70 to 90 cm; wherein the X direction is: the length direction of the acoustomagnetic anti-theft tag is parallel to the ground and perpendicular to the surface of the detection antenna of the double-door detector Ultrapost of the acoustomagnetic anti-theft tag, and the installation distance of the detection antenna is 6 feet or 1.8 meters.

[0032] In some embodiments, the alarm distance of the acoustomagnetic anti-theft tag in the Y direction is 20 to 40 cm; wherein the Y direction is: the length direction of the acoustomagnetic anti-theft tag is parallel to the ground and parallel to the surface of the detection antenna of the double-door detector Ultrapost of the acoustomagnetic anti-theft tag, and the installation distance of the detection antenna is 6 feet or 1.8 meters.

[0033] In some embodiments, the alarm distance of the acoustomagnetic anti-theft tag in the Z direction is 40 to 65 cm; wherein the Z direction is: the length direction of the acoustomagnetic anti-theft tag is perpendicular to the ground and parallel to the surface of the detection antenna of the double-door detector Ultrapost of the acoustomagnetic anti-theft tag, and the installation distance of the detection antenna is 6 feet or 1.8 meters.

[0034] In some embodiments, the method of manufacturing the biasing wire comprises:

[0035] The alloy disc is subjected to annealing and softening heat treatment, and then cold-drawn (or heat-treated) at a cross-sectional reduction rate greater than 90% to obtain the bias wire.

[0036] Compared to the prior art, the acousto-magnetic anti-theft tag disclosed in the present invention uses a very low-cost metal wire cold-drawing process to produce a filamentous biasing element. Compared to the sheet-like biasing element produced by the cold-rolling process in the prior art, the biasing wire of the present invention has sufficient shape anisotropy in the large deformation texture along the axial direction due to its filamentous long strip structure, and has better hysteresis loop squareness, so that the magnetic flux of the biasing wire along the length direction is stable, thereby making the acousto-magnetic tag have excellent alarm performance. At the same time, the cross-sectional area of ​​the wire material changes little relative to the steel strip after cold rolling, which also makes the magnetic flux of the biasing element after magnetization very stable, thereby making the acousto-magnetic tag have excellent alarm performance. In addition, the amount of processing scrap of cold-drawn wire material is usually less than that of cold-rolled steel strip, which reduces costs.

[0037] Compared to the existing technology, when a thin sheet of biasing piece is attached to the sealing surface of the label resonant cavity, if double-sided tape is directly applied to the adhesive-free sealing surface, the biasing piece has a large projected area, so a piece of double-sided tape must be pre-applied to the sealing surface to adhere the inner surface of the biasing piece, and then double-sided tape is applied to the outer surface of the biasing piece to prevent the label from being pulled away from the adhesive surface. The biasing wire of the present invention has a very small projected area, eliminating the need for pre-applied double-sided tape. Instead, a layer of double-sided tape can be directly applied to the biasing wire to securely adhere the biasing piece, making it difficult for the label to be pulled away after being attached to the product surface. This significantly reduces material costs and simplifies the processing process.

[0038] The acoustomagnetic tags made of bias wires show better performance in both magnetization activation and deactivation demagnetization than those made of bias plates, because the magnetization and demagnetization fields of bias wires are more directional than those of bias plates.

[0039] In addition, compared to the magnetic "pinning" of the resonant plate by the "end face" of the bias plate, the magnetic "pinning" or "damping" effect of the "end point" of the bias wire on the resonant plate is reduced. Under the same magnetic flux, the tag resonance amplitude can be larger.

[0040] In addition, in some embodiments, low-cost materials such as high-carbon steel without any Co or Ni are directly stretched to a cross-sectional area of ​​0.03 to 0.79 mm using a large deformation amount. 2 The bias wire is cut into sections to make the bias wire element of the acousto-magnetic tag, which produces an unexpectedly good alarm effect and excellent large-scale activation and efficient deactivation performance. It avoids the expensive high-precision cold rolling and subsequent high-precision stripping processing costs, and breaks the inertial thinking that metal wire is not suitable for making acousto-magnetic tag bias elements, and successfully makes a practical acousto-magnetic tag. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 is a schematic structural diagram of an acousto-magnetic anti-theft tag provided by an embodiment of the present invention;

[0042] FIG2 is a schematic diagram of the XYZ detection directions of the acousto-magnetic anti-theft tag provided by an embodiment of the present invention in a double-door detector Ultrapost (installation distance is 6 feet or 1.8 meters);

[0043] FIG3 is a first configuration of a bias wire in an acousto-magnetic anti-theft tag provided by an embodiment of the present invention;

[0044] FIG4 is a second configuration of a bias wire in an acousto-magnetic anti-theft tag provided by an embodiment of the present invention;

[0045] FIG5 is a third configuration of a bias wire in an acousto-magnetic anti-theft tag provided by an embodiment of the present invention;

[0046] FIG6 is a fourth configuration of a bias wire in an acousto-magnetic anti-theft tag according to an embodiment of the present invention;

[0047] FIG7 is a fifth configuration of a bias wire in an acousto-magnetic anti-theft tag according to an embodiment of the present invention;

[0048] FIG8 is a sixth configuration of a bias wire in an acousto-magnetic anti-theft tag according to an embodiment of the present invention;

[0049] FIG. 9 is a seventh configuration of a bias wire in an acousto-magnetic anti-theft tag provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0051] Traditional acousto-magnetic anti-theft tags consist of a resonant plate and a sheet-shaped biasing element. This sheet-shaped biasing element is manufactured through a difficult cold rolling process. Currently, there are no reports of using a bias wire as the biasing element in acousto-magnetic anti-theft tags, and no literature has reported that bias wire can be used to create commercially viable acousto-magnetic anti-theft tags. Conventional technology believes that the bias wire is too small relative to the size of the resonant plate, and the magnetic flux may be insufficient, making it impossible to produce a practical acousto-magnetic anti-theft tag with satisfactory alarm performance.

[0052] In order to overcome this existing technical bias, this embodiment provides the following solutions:

[0053] An acoustic magnetic anti-theft tag comprises: a resonance plate and at least one bias wire for providing a bias magnetic field for the resonance plate; the cross-sectional area of ​​the bias wire is 0.03 to 0.79 mm2 .

[0054] Furthermore, referring to Figure 1, in addition to the bias wire 1 and resonance piece 2 mentioned above, the acoustomagnetic anti-theft tag also includes a box body 3, a cover film 4, a box lid 5, and double-sided tape 6. One or more resonance pieces 2, which are superimposed on each other and match the size of the box body, are placed in the cavity of the box body 3. The length of the resonance piece is 35-45mm, the width is 2.3-10mm, and the resonance piece is an amorphous resonance element. The box body 3 is covered with a box lid 5 composed of double-sided tape 6 and a cover film 4. The cover film 4 and the resonance piece 2 are arranged in layers. The bias wire 1 is arranged inside or outside the box body 3, close to the resonance piece 2. The resonant frequency of the acoustomagnetic anti-theft tag is 57.1-58.9kHz. A further preferred embodiment is that the resonant frequency of the acoustomagnetic anti-theft tag is 57.5-58.5kHz.

[0055] For example, the cross section of the bias wire is circular. Assuming a diameter of 0.5 mm, the corresponding cross-sectional area is approximately 0.20 mm. 2 The diameter can also be 0.4mm, 0.6mm, 0.7mm, 1.0mm, etc., or other sizes, as long as the cross-sectional area is within 0.03-0.79mm. 2 That’s it, no further elaboration will be given here.

[0056] It is worth noting that the cross-section of the bias wire is not limited to a circle, but can also be an ellipse, a square, etc. By using different molds during the production (cold drawing) of the bias wire, bias wires with different cross-sectional shapes can be obtained, which is not limited here.

[0057] Whether the bias material after cold drawing needs heat treatment to achieve a DC coercivity index of 8-55 Oe is well known to those skilled in the art. How to manufacture a qualified resonant plate is also a well-known technology and will not be described again.

[0058] When implementing the embodiments of the present invention, the inventors discovered after creative work that: compared with the sheet-shaped biasing elements produced by the cold rolling process in the prior art, the present invention adopts a low-cost metal wire cold drawing process to produce the wire-shaped biasing wire element, and the raw material is directly drawn into the metal wire with a large deformation amount (preferably a cross-sectional reduction rate greater than 90%). The large deformation texture along the axial direction produces sufficient shape anisotropy, which is cut into segments to obtain a cross-sectional area of ​​0.03 to 0.79 mm. 2The bias wire is directly used as the bias element of the acoustomagnetic anti-theft tag, which produces an unexpectedly good alarm effect. It avoids the expensive high-precision cold rolling and subsequent high-precision strip processing costs, and does not need to adopt the precision steel strip cold rolling process that is more difficult to process. In addition, some bias wires can have a good stable magnetic flux along the length direction without heat treatment after cold drawing, which makes the acoustomagnetic anti-theft tag have excellent alarm performance. The bias wire after heat treatment can also be used to make a very stable acoustomagnetic tag. The present invention proves that the bias wire after cold drawing has a better hysteresis loop squareness in the axial direction than the cold-rolled thin strip, breaking the inertial thinking that metal wire is not suitable for the bias element of the acoustomagnetic anti-theft tag, and successfully making a practical acoustomagnetic anti-theft tag.

[0059] In an optional embodiment, the bias wire has a length of 10-40 mm. For example, the bias wire can have a length of 10 mm, 20 mm, 30 mm, 35 mm, etc. Of course, other values ​​within this length range can also be selected based on practical requirements, and further details are not provided here. The bias wire length range of the embodiments of the present invention is related to the size of the resonant plate, and those skilled in the art can adjust the bias wire length based on practical needs.

[0060] In an optional embodiment, the number of the bias wire is one, and the length of the bias wire is 10-40 mm. In an embodiment of the present invention, if the number of the bias wire is only one, in order to ensure the anti-theft performance of the acousto-magnetic anti-theft tag, the length of the bias wire is set to 30-40 mm.

[0061] For example, the number of bias wires is 1, the diameter is 1.0 mm, and the length is 35 mm. Alternatively, the number of bias wires is 1, the diameter is 0.6 mm, and the length is 30 mm. Alternatively, the number of bias wires is 1, the diameter is 0.7 mm, and the length is 40 mm. Alternatively, the number of bias wires is 1, the diameter is 0.7 mm, and the length is 32 mm. Of course, other values ​​within the specified range can also be selected according to actual requirements, and no further details will be given here.

[0062] In an optional embodiment, the number of the bias wires is 2-3, and the length of each bias wire is 10-40 mm; preferably 10-35 mm; more preferably 22-35 mm.

[0063] For example, the number of offset wires is 2, each with a diameter of 0.5 mm and lengths of 22 mm and 30 mm, respectively. Alternatively, the number of offset wires is 3, each with a diameter of 0.2 mm and lengths of 22 mm, 25 mm, and 30 mm, respectively. Alternatively, the number of offset wires is 2, each with a diameter of 0.4 mm and length of 30 mm, respectively. Of course, other values ​​within the specified range can also be selected based on actual requirements, and further details will not be given here.

[0064] In an optional embodiment, when the bias wire is longer than 30 mm, the bias wire is curved. In this embodiment of the present invention, due to the size limitations of the acousto-magnetic anti-theft tag, for example, when the bias wire is positioned at the bottom of the resonant cavity of the resonant plate, the size of the resonant cavity is limited. Therefore, when the bias wire is longer than 30 mm, the bias wire is configured to be curved.

[0065] In an optional embodiment, the bias wire is a semi-hard magnetic bias wire or a soft magnetic bias wire.

[0066] It is worth noting that the semi-hard magnetic bias wire or soft magnetic bias wire can be repeatedly decoded and activated. The bias wire is a key component in the acousto-magnetic anti-theft tag, which enables the detection system to clearly distinguish the activated state and the inactivated state (decoded state) of the acousto-magnetic anti-theft tag. For example, the acousto-magnetic anti-theft tag on the paid goods can be demagnetized and decoded on the decoder to allow the goods to leave the store without triggering the alarm at the door.

[0067] In an optional embodiment, each bias wire has a DC coercivity of 8-55 Oe. Coercivity is a characteristic of magnetic materials, referring to the reverse magnetic field strength required to reduce the magnetization intensity of a magnetic material to zero after it has reached magnetic saturation. It represents the material's ability to resist demagnetization. When implementing this embodiment of the present invention, a DC coercivity of 8-55 Oe can improve the performance of repeated decoding and activation of the acoustomagnetic anti-theft tag.

[0068] In an alternative embodiment, the bias wire is composed of carbon and iron.

[0069] Specifically, the bias wire of the present invention, which is composed solely of carbon and iron, does not exist in the prior art. This bias wire, produced through a cold-drawing process, exhibits a stable magnetic flux along its length, resulting in excellent alarm performance for the acousto-magnetic tag. Furthermore, this invention breaks away from the conventional wisdom that nickel must be added to the bias element. The carbon-iron bias wire still maintains the anti-theft performance of the acousto-magnetic anti-theft tag while reducing its production cost.

[0070] In an optional embodiment, when the bias wire is composed of carbon and iron, the weight percentage of carbon in the bias wire is 0.6-1.0 wt %.

[0071] Specifically, the ratio of carbon to iron affects the performance of the bias wire. As the carbon content increases, the yield point and tensile strength increase. Carbon can increase the cold brittleness and aging sensitivity of the bias wire. In practical applications, controlling the carbon content has a great impact on the performance of the bias wire production. Since the length of the bias wire is affected by the size of the acousto-magnetic anti-theft tag, when the bias wire is too long, it needs to be bent. Considering that too high a carbon content will reduce the plasticity and impact toughness of the bias wire, and reduce its resistance to atmospheric corrosion, therefore, limiting the weight percentage of carbon to within 1.1wt% can make the bias wire less likely to break when manufacturing the acousto-magnetic anti-theft tag, and can increase the service life of the tag.

[0072] In an optional embodiment, the bias wire is composed of nickel and iron. It is understandable that the bias wire is composed only of nickel and iron without other transition metals, and the components are simple, which simplifies the initial raw material production process.

[0073] In an optional embodiment, when the bias wire is composed of nickel and iron, the weight percentage of nickel in the bias wire is 8-18 wt %.

[0074] In an optional embodiment, when the bias wire is composed of manganese and iron, the weight percentage of manganese in the bias wire is 8-14 wt %.

[0075] In an alternative embodiment, the bias wire is composed of nickel, at least one transition metal, and iron.

[0076] In an optional embodiment, when the bias wire is composed of nickel, at least one transition metal, and iron, the weight percentage of nickel in the bias wire is 45-55 wt%, and the total weight percentage of the at least one transition metal does not exceed 5 wt%. For example, the weight percentage of nickel in the bias wire is 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, etc. Of course, other values ​​within this weight percentage range can also be selected according to actual requirements, and further details are not provided here.

[0077] In an optional embodiment, when the bias wire is composed of nickel, at least one transition metal, and iron, the weight percentage of nickel in the bias wire is 8-22 wt%, and the total weight percentage of the at least one transition metal does not exceed 5 wt%. For example, the weight percentage of nickel in the bias wire is 8 wt%, 11 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, etc. Of course, other values ​​within this weight percentage range can also be selected according to actual requirements, and further details are not provided here.

[0078] In an optional embodiment, the manufacturing process of the bias wire includes: subjecting the alloy disc to annealing and softening heat treatment, cold drawing the alloy disc with a cross-sectional reduction rate greater than 90%, and then heat treating to obtain the bias wire.

[0079] For example, for metal materials, cold drawing refers to drawing at room temperature in order to obtain a certain shape and certain mechanical properties, applying longitudinal tension and transverse pressure to the material at the same time, thereby improving the strength of the product. Cold drawing processing must be carried out on a special cold drawing machine. Compared with cold rolling, the cold drawing process is relatively simple, which can improve the efficiency of producing bias wire and reduce production costs. In an embodiment of the present invention, after the alloy disc (unprocessed bias material) is annealed and softened, the alloy disc is cold drawn with a large deformation amount of greater than 90% of the cross-sectional shrinkage rate, and the cross-sectional area is cold drawn to 0.03 to 0.79 mm. 2 , (or after heat treatment) to obtain a magnetic bias wire, which is cut into bias wire elements with a length of 20-40 mm.

[0080] In a specific embodiment, the detection of the acoustomagnetic anti-theft tag uses a commercially available detector, for example, an Ultrapost double-door detector produced by Sensormatic, which is installed in large quantities at the entrances of various stores. The center distance between the two doors is 6 feet or 1.8 meters (that is, the installation distance of the detection antenna is 6 feet or 1.8 meters). The detection method for the tag of the present invention is to detect the tag at a height of one meter from the ground. The XYZ detection direction is shown in Figure 2. The tag approaches the detector surface on the closer side until the alarm is triggered. The length from the center of the tag to the alarm surface on the closer end at this time is measured as the alarm distance. The X direction is: the length direction of the acoustomagnetic anti-theft tag is parallel to the ground and perpendicular to the surface of the detection antenna of the detector Ultrapost of the acoustomagnetic anti-theft tag. The Y direction is: the length direction of the acoustomagnetic anti-theft tag is parallel to the ground and parallel to the surface of the detection antenna of the detector Ultrapost of the acoustomagnetic anti-theft tag. The Z direction is: the length direction of the acoustomagnetic anti-theft tag is perpendicular to the ground and parallel to the surface of the detection antenna of the detector Ultrapost of the acoustomagnetic anti-theft tag.

[0081] In various embodiments of the present invention, the alarm distance of the acoustomagnetic anti-theft tag in the X direction in an Ultrapost double-door detector with an installation width of 6 feet or 1.8 meters is 70 to 90 cm; in an embodiment of the present invention, the alarm distance of the acoustomagnetic anti-theft tag in the Y direction in an Ultrapost detector with an installation width of 6 feet or 1.8 meters is 20 to 40 cm; in an embodiment of the present invention, the alarm distance of the acoustomagnetic anti-theft tag in the Z direction in a double-door Ultrapost detector with an installation width of 6 feet or 1.8 meters is 40 to 65 cm.

[0082] To facilitate understanding of the above-mentioned embodiments, test results of the alarm distance of the acoustomagnetic anti-theft tag under different resonance plate properties are provided herein. When testing the alarm distance data of each group of acoustomagnetic anti-theft tags, the acoustomagnetic anti-theft tag is moved in the X, Y, or Z direction respectively to shorten the distance between the acoustomagnetic anti-theft tag and the detector surface at the closer end until the alarm is triggered.

[0083] Test example 1:

[0084] The alloy disc (after annealing and softening heat treatment) is multi-stage cold drawn with a large deformation (preferably greater than 90% cross-sectional shrinkage) to a diameter of 0.5 mm (cross-sectional area of ​​about 0.2 mm). 2 A magnetic bias wire with a coercivity of 29 Oe was cut into two bias wires, 10 and 30 mm in length. The alloy contained 0.6-1.1 wt% C, with the balance being Fe. The two bias wires were placed near the resonant cavity of the three resonant plates. The placement of the bias wires is shown in Figure 3. The test alarm distances were 90 cm in the X direction, 38 cm in the Y direction, and 61 cm in the Z direction.

[0085] Test example 2:

[0086] The alloy disc (after annealing and softening heat treatment) is multi-stage cold drawn with large deformation (greater than 90% cross-sectional shrinkage) to a diameter of 0.2mm (cross-sectional area of ​​about 0.03mm). 2 ) A magnetic bias wire with a coercivity of 8-10 Oe was cut into 20, 20, and 30 mm lengths to obtain three bias wires. The alloy contained 49 wt% Ni, up to 5 wt% of one or more other transition metals, and the balance was Fe. The three bias wires were placed near the resonant cavity of two 6.8 mm wide resonant plates. The placement of the bias wires is shown in Figure 4. The test alarm distances were 90 cm in the X direction, 35 cm in the Y direction, and 58 cm in the Z direction.

[0087] Test example three:

[0088] The alloy disc (after annealing and softening heat treatment) is cold drawn with a large deformation (greater than 90% cross-sectional shrinkage) to a diameter of 0.4 mm (cross-sectional area of ​​about 0.13 mm) 2 ) After heat treatment, a magnetic bias wire with a coercivity of 35 Oe was obtained. This wire was then cut into two 30 mm long bias wires. The alloy contained 18 wt% Ni, up to 5 wt% of one or more other transition metals, and the balance was Fe. The two bias wires were placed near the resonant cavity of four 4.2 mm wide resonant plates. The placement of the bias wires is shown in Figure 5. The test alarm distance was 80 cm in the X direction, 29 cm in the Y direction, and 55 cm in the Z direction.

[0089] Test example 4:

[0090] The alloy disc (after annealing and softening heat treatment) is cold drawn with a large deformation (greater than 90% cross-sectional shrinkage) to a diameter of 1.0 mm (cross-sectional area of ​​about 0.79 mm) 2 ) After heat treatment, a magnetic wire with a coercivity of 15 Oe was obtained. This wire was cut into 35 mm pieces to form a bias wire. The alloy contained 14 wt% Mn, with the remainder being Fe. This bias wire was placed near the resonant cavity of five 2.6 mm wide resonant plates. The placement of the bias wire is shown in Figure 6. The test alarm distance was 75 cm in the X direction, 20 cm in the Y direction, and 51 cm in the Z direction.

[0091] Test example 5:

[0092] The alloy disc (after annealing and softening heat treatment) is cold drawn with a large deformation (greater than 90% cross-sectional shrinkage) to a diameter of 0.6 mm (cross-sectional area of ​​about 0.29 mm) 2 ) After heat treatment, a magnetic bias wire with a coercivity of 20 Oe was obtained. This wire was cut into 30 mm pieces to form a bias wire. The alloy contained 20 wt% Ni, up to 5 wt% of one or more other transition metals, and the balance was Fe. This bias wire was placed at the bottom of the resonant cavity of five 2.6 mm wide resonant plates. The placement of the bias wire is shown in Figure 7. The test alarm distance was 72 cm in the X direction, 23 cm in the Y direction, and 49 cm in the Z direction.

[0093] Test example six:

[0094] The alloy disc (after annealing and softening heat treatment) is cold drawn with a large deformation (greater than 90% cross-sectional shrinkage) to a diameter of 0.7 mm (cross-sectional area of ​​about 0.38 mm) 2) After heat treatment, a magnetic bias wire with a coercivity of 35 Oe was obtained. This wire was cut into 40 mm pieces to form a bias wire. The alloy contained 8 wt% Mn, with the remainder being Fe. This bias wire was bent and placed near the resonant cavity of three 6.0 mm wide resonant plates. The placement of the bias wire is shown in Figure 8. The test alarm distance was 80 cm in the X direction, 31 cm in the Y direction, and 45 cm in the Z direction.

[0095] Test example seven:

[0096] The alloy disc (after annealing and softening heat treatment) is cold drawn with a large deformation (greater than 90% cross-sectional shrinkage) to a diameter of 0.7 mm (cross-sectional area of ​​about 0.38 mm) 2 ) After heat treatment, a magnetic bias wire with a coercivity of 35 Oe was obtained. This wire was cut into 32 mm pieces to form a bias wire. The alloy contained 10 wt% Ni, with the remainder being Fe. This bias wire was bent and placed near the resonant cavity of four 4.0 mm wide resonant plates. The placement of the bias wire is shown in Figure 9. The test alarm distance was 78 cm in the X direction, 25 cm in the Y direction, and 52 cm in the Z direction.

[0097] The integration results of the above 7 samples can be found in Table 1.

[0098] Table 1 Detection distances corresponding to different specifications of acoustic magnetic anti-theft tags

[0099] The above examples 1 to 7 are experimental data obtained with different compositions, and different resonant sheet widths and numbers of sheets. The alarm distance of the acoustomagnetic anti-theft tag in the X-direction can reach approximately 70 to 90 cm, that is, the effective protection width can also reach approximately 1.4 to 1.8 meters. This exceeds the width of another widely used EAS protection system on the market, the RF protection system (usually installed with a width of one meter), and has broad commercial prospects.

[0100] Furthermore, the acousto-magnetic anti-theft labels are closely arranged on the same plane as a single sheet, with at least one edge of the acousto-magnetic anti-theft label separated from the edge of an adjacent acousto-magnetic anti-theft label by less than 0.1 mm. A single sheet of 40-120 labels is formed, and each box of commercially available labels contains at least 20 sheets. The acousto-magnetic anti-theft labels are arranged parallel to each other and perpendicular to the length of the supporting base tape to form a roll. The edges of the acousto-magnetic anti-theft labels are separated from the edges of adjacent acousto-magnetic anti-theft labels by 2-4 mm. A single roll of 2000-8000 labels is formed, and each box of commercially available labels contains at least one roll.

[0101] In an embodiment of the present invention, a bias wire is produced by cold-drawing a wire material. Compared with the sheet-like bias element produced by the cold-rolling process in the prior art, the bias wire of the present invention has sufficient shape anisotropy in the large deformation texture along the axial direction due to its long filamentous strip structure, and has better squareness of the hysteresis loop, so that the magnetic flux of the bias wire along the length direction is stable, thereby making the acousto-magnetic tag have excellent alarm performance. At the same time, the cross-sectional area of ​​the wire material changes less than that of the steel strip after cold rolling, which also makes the magnetic flux fluctuation of the biasing member after magnetization small, thereby making the acousto-magnetic tag have excellent alarm performance. In addition, the processing scrap of cold-drawn wire material is usually less than that of cold-rolled steel strip, which reduces costs. In addition, in some embodiments, low-cost materials such as high-carbon steel without any Co and Ni are directly drawn to a cross-sectional area of ​​0.03 to 0.79 mm with a large deformation amount. 2 The bias wire was cut into sections and used directly as the bias element of the acoustic magnetic tag, which produced an unexpectedly good alarm effect. It avoided the expensive high-precision cold rolling and subsequent high-precision slitting processing costs, and broke the inertial thinking that metal wire is not suitable for making the bias element of the acoustic magnetic tag, and successfully made a practical acoustic magnetic tag.

[0102] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An acoustic magnetic anti-theft tag, characterized in that: include: A resonance plate and at least one bias wire for providing a bias magnetic field for the resonance plate; The cross-sectional area of ​​the offset wire is 0.03 to 0.79 mm 2 .

2. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The length of the bias wire is 10-40 mm.

3. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The number of the bias wire is 1, and the length of the bias wire is 10-40 mm; preferably, the number of the bias wire is 1, and the length of the bias wire is 30-40 mm.

4. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The number of the bias wires is 2-3, and the length of each bias wire is 10-40 mm; preferably, the number of the bias wires is 2-3, and the length of each bias wire is 10-35 mm.

5. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: When the length of the bias wire is greater than 30 mm, the bias wire is bent.

6. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The bias wire is a semi-hard magnetic bias wire or a soft magnetic bias wire.

7. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The DC coercive force of each bias wire along the axial direction is 8-55 Oe.

8. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The bias wire is made of a low-cost Fe-based alloy material; preferably, the bias wire is made of a Fe-based alloy containing no or a low content of Co or Ni.

9. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The bias wire is composed of carbon and iron.

10. The acousto-magnetic anti-theft tag according to claim 9, characterized in that: The weight percentage of carbon in the bias wire is 0.6-1.1 wt%.

11. The acoustic-magnetic anti-theft tag according to claim 1, characterized in that: The bias wire is composed of an iron-based alloy that also contains nickel.

12. The acousto-magnetic anti-theft tag according to claim 11, characterized in that: The weight percentage of nickel in the bias wire is 8-18%.

13. The acousto-magnetic anti-theft tag according to claim 1, characterized in that: The bias wire is composed of an iron-based alloy also containing manganese.

14. The acousto-magnetic anti-theft tag according to claim 13, characterized in that: The weight percentage of manganese in the bias wire is 8-14%, and the weight percentage of other transition metals is 0-5wt%.

15. The acousto-magnetic anti-theft tag according to claim 1, characterized in that: The bias wire is composed of an alloy having an iron base and also containing nickel and at least one other transition metal.

16. The acousto-magnetic anti-theft tag according to claim 15, characterized in that: The weight percentage of nickel in the bias wire is 45-55wt%, and the total weight percentage of at least one other transition metal does not exceed 5wt%; or the weight percentage of nickel in the bias wire is 8-22wt%, and the total weight percentage of at least one other transition metal does not exceed 5wt%.

17. The acousto-magnetic anti-theft tag according to claim 1, characterized in that: The alarm distance of the acoustic magnetic anti-theft tag in the X direction is 70 to 90 cm; the X direction is: the length direction of the acoustic magnetic anti-theft tag is parallel to the ground and perpendicular to the surface of the detection antenna of the double-door detector Ultrapost of the acoustic magnetic anti-theft tag, and the installation distance of the detection antenna is 6 feet or 1.8 meters.

18. The acousto-magnetic anti-theft tag according to claim 1, characterized in that: The alarm distance of the acoustic magnetic anti-theft tag in the Y direction is 20 to 40 cm; the Y direction is: the length direction of the acoustic magnetic anti-theft tag is parallel to the ground and parallel to the surface of the detection antenna of the double-door detector Ultrapost of the acoustic magnetic anti-theft tag, and the installation distance of the detection antenna is 6 feet or 1.8 meters.

19. The acousto-magnetic anti-theft tag according to claim 1, characterized in that: The alarm distance of the acoustic magnetic anti-theft tag in the Z direction is 40 to 65 cm; the Z direction is: the length direction of the acoustic magnetic anti-theft tag is perpendicular to the ground and parallel to the surface of the detection antenna of the double-door detector Ultrapost of the acoustic magnetic anti-theft tag, and the installation distance of the detection antenna is 6 feet or 1.8 meters.

20. A method for preparing a bias wire having a DC coercivity of 8-55 Oe, comprising: The alloy disc is subjected to annealing and softening heat treatment, and the alloy disc is cold-drawn with a cross-sectional shrinkage rate greater than 90% to directly obtain the bias wire, or further subjected to corresponding heat treatment to obtain the bias wire.

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