JPH0711582B2 - Magnetic marker - Google Patents

Description

The present invention relates to a magnetic marker attached to an article in order to detect the quantity, type, etc. of the article.

[Prior Art] It is known that a marker is attached to an article and the marker is used to detect the quantity and type of the article or to prevent the article from being stolen. Conventionally, such a marker is also protected against damage and theft, and since the marker is attached to an article so that the marker cannot be seen directly, magnetism or microwave is applied. For example, a marker is used to apply a magnetic field using an amorphous magnetic ribbon or a thin wire, or aluminum foil is irradiated with microwaves. In particular, the method of detecting the magnetic flux change that occurs in the amorphous magnetic material by passing the target object to be detected with the amorphous magnetic material attached as a marker in an alternating magnetic field is one that utilizes the excellent soft magnetic characteristics of the amorphous magnetic material. Yes, it is excellent in that a highly sensitive and lightweight marker can be constructed.

[Problems to be Solved by the Invention] Although a marker using an amorphous magnetic material is useful, it still has the following problems. Conventionally, in this type of marker, the magnetic materials used are all made of thin strips or thin wires having the same magnetic characteristics, and the voltage signal of the detection coil generated by the alternating magnetic field is determined only by the magnetic characteristics. The presence / absence of the article, that is, only the presence / absence of the article and the quantity of the article cannot be recognized. Therefore, it is desirable to be able to use this marker when, for example, a large number of products are classified by manufacturer and counted. Therefore, it is necessary to further improve the structure and use of the marker.

The present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic marker having a structure that enables not only the presence / absence of an article to be attached to the article but also the identification (type) of the article. Especially.

[Means for Solving the Problems]

The magnetic marker of the present invention is arranged in the longitudinal direction and has a magnetic hysteresis characteristic of a rectangular shape and a high magnetic permeability, and a plurality of magnetic ribbons or fine wires having different magnetic flux magnitudes extend in the extension direction of one end of each of these magnetic ribbons. Alternatively, an article can be identified by attaching a magnetic material having magnetism having a magnetic force that changes the coercive force for reversing the magnetization of the thin wire.

[Action]

In the magnetic marker of the present invention, a plurality of thin strips or thin wires of a soft magnetic material having a rectangular BH characteristic are arranged in parallel in the longitudinal direction thereof, and each soft magnetic material is magnetized as a bias magnetic field. By adding a hard magnetic material, the magnitude of the magnetic flux reversal magnetic field due to the external magnetic field of the soft magnetic material will be different from each other, and further, the maximum magnetic flux of each soft magnetic material will change the original material characteristics or cross-sectional area. Since the value is different depending on the magnetic marker, the phase of magnetization reversal and the amount of change in magnetic flux are different for each soft magnetic ribbon or thin wire when an external AC magnetic field is applied to the magnetic marker, and each has its own pulse voltage train. The marker type can be determined by recognizing the pattern of these voltage sequences obtained by the measuring instrument.

〔Example〕

 The present invention will be described below based on examples.

First, an outline of an article identification device to which the magnetic marker according to the present invention is applied will be described. FIG. 1 is a schematic diagram of a main part configuration showing an example of the apparatus. In FIG. 1 , the article 2 to which the magnetic marker 1 is attached is on a belt 4 stretched between two rotating parts 3 and moves in the direction of the arrow together with the belt 4 by the rotation of the rotating part 3. The excitation coil 5, the AC oscillator 6, the detection coil 7, and the measuring instrument 8 are also shown in an enlarged view in FIG. In FIG. 2, an exciting coil 5 for generating an alternating magnetic field is connected to an alternating current oscillator 6, and a detecting coil 7 for detecting a change in magnetic flux due to reversal of magnetization of the magnetic marker 1 caused by the alternating magnetic field as an induced electromotive voltage is connected to a measuring instrument 8. To be done. The measuring instrument 8 has a function of identifying the pulse voltage train generated in the detection coil 7 by pattern recognition. The detection coil 7 is a twin coil in order to cancel the induced electromotive voltage generated by the exciting coil 5.

With the above configuration, as shown in FIG. 1 , when a plurality of articles 2 to which the magnetic markers 1 are attached, that is, the objects to be detected ride on the belt 4 and pass near the exciting coil 5, they are generated there. The magnetization of the magnetic marker 1 is reversed by the alternating magnetic field present, and the change in magnetic flux due to this is detected as a pulse voltage by the detection coil 7, whereby the measuring instrument 8 can identify the type of each detected object.

Next, the function of the magnetic marker according to the present invention will be described.

The magnetic marker 1 is composed of, for example, a plurality of Fe-based amorphous magnetic fine wires and is attached to an article 2 which is an object to be detected. The magnetic marker is fixed to a plastic material or the like to form a detection element. The detection element can be attached to the article 2 for use. Here, a detection element having a magnetic marker will be described.

FIG. 3 is a partially cutaway perspective view of the detection element 10 having the magnetic marker 11 and installed on the fixed plate 9.
(A), (b), and (c) represent three types of cases. 1A, 1B, and 1C are amorphous magnetic thin wires, but in the embodiment of FIG. 3, the magnetic flux reversal limit magnetic field in an alternating magnetic field is increased due to the strong two-layer structure stress distribution and magnetic anisotropy,
An Fe-based amorphous magnetic wire with outstanding rectangular characteristics is used. In the following, as for (a), (b), and (c) three types of embodiments shown in FIG. 3, the Φ-H characteristic diagrams of FIGS. 4 to 9 and the pulse voltage train generated in the detection coil are also shown. It will be described with reference to FIG. FIG. 3 (a) shows three Fe-based amorphous magnetic wires 1A, 1B, 1C having almost the same coercive force and maximum magnetic flux.
Are arranged at regular intervals in the longitudinal direction, and are fixed between fixing plates 9 such as a thin plastic to form the detecting element 10 . Here, the magnetic fine wires 1B and 1C are provided with bias magnetic field applying magnetic materials 11B and 11C having different magnetization levels to the amorphous fine magnetic wires 1B and 1C, respectively. As the magnetic material for applying the bias magnetic field, a magnetically hard material such as Fe-Cr system having an appropriate residual magnetic flux and coercive force is used. 4 (a) to 4 (c) are Φ of the amorphous magnetic thin wires 1A, 1B, 1C.
Fig. 4 shows changes in -H characteristics, and when the characteristics of these thin wires are as shown in Fig. 4 (a), by adding magnetic materials 11B, 11C to the amorphous magnetic thin wires 1B, 1C,-△ HB respectively. ,-△ HC DC bias field is applied (△ H
B <ΔHC), the Φ-H characteristics of the amorphous magnetic wires 1B, 1C with respect to the external AC magnetic field H are shown in FIG. 4 (b),
The magnetic field that shifts to a higher magnetic field as shown in (c) and is reversed to the maximum magnetic flux side becomes higher like HB in FIG. 4 (b) and HC in FIG. 4 (c). Therefore, amorphous magnetic wire 1A, 1B,
The magnetic flux reversal magnetic field of 1C is HA <HB <HC, and the magnetic flux reversal in the AC magnetic field, that is, the induced electromotive voltage in the detection coil 7 is as shown in the voltage-time diagram showing the pulse voltage train in FIG. In the case of reversing to the maximum magnetic flux side (+ Φ), the induced electromotive voltage corresponding to the amorphous magnetic thin wires 1A → 1B → 1C is generated in time series. When reversing to −Φ side, 1C → 1B →
The order is 1A.

In FIG. 3 (a), since the maximum magnetic fluxes of the amorphous magnetic wires 1A, 1B, 1C are almost equal, the induced electromotive force can be obtained at almost the same level. Next, the embodiment of FIG. 3 (b) is Change the cross-sectional area of the amorphous magnetic wires 1A, 1B, 1C, that is, set the wire diameter to 1A <1B <1C, and make the maximum magnetic flux different from each other.
B and 1C are cases where hard magnetic materials having the same wire diameter for adding a bias magnetic field are added.

The Φ-H characteristics of the amorphous magnetic wires 1A, 1B, 1C in this case are shown in FIG. 6, where ΦmaxA <ΦmaxB <ΦmaxC. The induced voltage generated in the detection coil 7 is shown in FIG. The induced voltage is e _A <e _B <e _C from the difference of dΦ / dt corresponding to the level of the maximum magnetic flux.

The next embodiment shown in FIG. 3 (c) is an amorphous magnetic thin wire 1A.
In this case, a line 11A made of a hard magnetic material is added to and the bias magnetic field level is larger than the coercive force of the amorphous magnetic thin lines 1A, 1B, 1C. The wire diameter is 1A <1B <1C as in FIG. 3 (b).
Bias magnetic field of magnetic materials 11A, 11B, 11C is-△ HA,-
△ HB,-△ HC are added. The Φ-H characteristics are as shown in FIGS. 8A to 8C, and the induced electromotive voltage of the detection coil 7 is as shown in FIG. 9.

In the embodiment shown in FIGS. 3 (a) to 3 (c), the bias magnetic field directions for the amorphous magnetic thin wires 1A, 1B, 1C are all set to the same direction, but bias is applied by the amorphous magnetic thin wires 1A, 1B, 1C in the same detection element. If the magnetic field directions are made different, the time width of the pulse voltage train obtained in time series for each amorphous magnetic thin wire can be made large, so that the number of identifications increases and the configuration of the magnetic marker becomes easy. Further, in the embodiment shown in FIGS. 3 (a) to 3 (c), a thin wire is attached as the magnetic material for applying a bias magnetic field, but as shown in FIG. 10, a hard magnetic thin film is formed on the substrate 12 by a sputtering method or the like. After forming 13A, 13B, and 13C in parallel so as to have a predetermined magnetic level at regular intervals, amorphous magnetic thin wires are formed.
Similar effects can be obtained as the detection element 15 in which 1A, 1B and 1C are fixed by the fixing plate 14 and installed.

Further, in the examples shown in FIGS. 3 (a) to 3 (c), the Fe-based amorphous magnetic material having a remarkable square characteristic was used as the material of the magnetic marker. Any magnetic material having a rectangular and high magnetic permeability, whose pulse-like output waveform of voltage can be separated in time series by the bias magnetic field according to the present invention, can be applied.

〔The invention's effect〕

A magnetic marker attached to an article and recognizing the same, wherein a plurality of soft magnetic material ribbons or thin wires having a square B-H characteristic and different saturation magnetic fluxes are magnetized as a bias magnetic field. By arranging so that each soft magnetic material has a different switching field, when the magnetizations of these soft magnetic materials are reversed by the external magnetic field, the magnetic speed change corresponding to a plurality of magnetization reversals is detected in time series. It is possible to detect as a pulse voltage train by the coil, and after the signal processing of this pulse voltage train, a pattern can be recognized by a measuring instrument, and as a result, even a magnetic marker, that is, the type of article can be effectively identified.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main part configuration of an article identification device to which a magnetic marker of the present invention is applied, FIG. 2 is a partially enlarged view of the device of FIG. 1, FIG. 3 (a), ( (b) and (c) are partially cutaway perspective views of a detection element having a magnetic marker of the present invention composed of three magnetic fine wires, and FIGS. 4, 6 and 8 are FIGS. 3 (a), (b) and (), respectively. Φ-H characteristic of the magnetic thin wire of the magnetic marker embodiment of c), FIGS. 5, 7, and 9 are FIGS. 3 (a), (b),
FIG. 10 is a voltage-time diagram showing a pulse voltage train generated in the detection coil in the magnetic marker embodiment (c), and FIG. 10 is a partially cutaway perspective view of the detection element of another embodiment of the magnetic marker according to the present invention. 1 , 11 ...... Magnetic marker, 1A, 1B, 1C ...... Amorphous magnetic fine wire 2 ...... Article 3 ...... Rotating part 4 ...... Belt 5
…… Excitation coil, 6 …… AC oscillator, 7 …… Detection coil, 8 …… Measuring instrument, 9,14 …… Fixing plate, 10, 15 …… Detecting element, 11A, 11B, 11C …… Magnetic material, 12 ...... Substrate, 13A, 13B, 1
3C: Magnetic ribbon.

Claims (1)

[Claims] 1. A magnetic marker which is attached to an object to be detected passing through an alternating magnetic field and which can recognize the object to be detected from a pulse voltage generated by the alternating magnetic field. A predetermined value that changes the coercive force for reversing the magnetization of these magnetic ribbons or thin wires in the extension direction of one end of each of the magnetic ribbons or thin wires that are arranged with intervals and exhibit rectangular magnetic hysteresis characteristics and have different magnetic flux magnitudes. A magnetic marker characterized by being accompanied by a magnetic material having the magnetic force of.