JPH02145988A - Detecting method of magnetic marker - Google Patents

Abstract

PURPOSE:To enable discrimination of a substance to be detected, by using at least one magnetic marker different in a magnetic hysteresis characteristic for each substance to be detected and by analyzing a waveform of a voltage outputted by a change in a magnetic flux generated in an alternating-current magnetic field. CONSTITUTION:A detecting element 9 is prepared by using two amorphous magnetic slender wires 1a and 1b having soft magnetism for a magnetic marker 11 and by fixing these wires in parallel with each other between fixing plates 10 of plastic or the like. For these wires, substances being different in a magnetic hysteresis characteristic are used so that the maximum magnetic flux of the slender wire 1a is larger than that of the slender wire 1b and that the coercive force of the slender wire 1a is smaller than that of the slender wire 1b. When an article having the element 9 stuck thereon is set to a discriminating device and an external alternating-current magnetic flux is applied thereto, an induced electromotive voltage being different in a waveform, an output level and a phase is detected as a single or compound waveform, since each magnetic material has different flux-field hysteresis characteristics (the coercive force, the maximum magnetic flux, permeability, etc.). By subjecting said waveform to a frequency analysis to discriminate a frequency pattern intrinsic to each marker 11, the classification of the article can be determined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of detecting a magnetic marker attached to an article in order to identify the type, quantity, etc. of the article.

[Conventional technology]

It is known to attach a marker to an article and use this marker to detect the quantity of the article or to prevent the article from being stolen. Conventionally, such markers have been made using magnetic or microwave-enabled markers, such as those that use an amorphous matrix ribbon or thin wire to apply solar radiation to the marker, or aluminum foil that is irradiated with microwaves. be. In particular, when an article with an amorphous magnetic material attached as a marker is passed through an alternating magnetic field, the magnetic properties of the amorphous conductive material are reversed by the alternating magnetic field, making it possible to detect magnetic field fluctuations, which is different from conventional amorphous matrix materials. It utilizes excellent soft magnetic properties, is highly sensitive, and is compact.

It has the excellent feature of being able to use lightweight markers.

FIG. 6 is a schematic diagram showing the main structure of an article identification device using an amorphous magnetic ribbon or thin wire as a marker. In FIG. 6, an article 2 to which a magnetic marker 1 in the form of an amorphous magnetic ribbon or thin wire is attached is placed on a belt 4 stretched between two rotating parts 3, and as the belt 4 travels in the direction of the arrow due to the rotation of the rotating parts 3. Move to. The assistance coil 5° The AC oscillator 6, the detection coil 7, and the measuring device 8 are also shown as enlarged views in FIGS. 7(a) and (bl).In FIG. A detection coil 7 is connected to the AC oscillator 6 and detects, as an induced electromotive force, a change in magnetic flux caused by magnetization reversal of the magnetic marker 1 caused by the AC magnetic field. The detection coil 7 has a function of identifying the pulse voltage train generated by the excitation coil 5 by pattern recognition.The detection coil 7 is a twin coil for canceling the induced electromotive force generated by the excitation coil 5.

The magnetic marker 1 is made of, for example, at least one magnetic ribbon or thin wire made of an amorphous alloy, and is attached to an article 2 that is an object to be detected. This can also be used as a detection element fixed on the article 2 by pasting it on the article 2.

As shown in FIG. 6, in this device, a plurality of articles 2 each having a magnetic marker 1 affixed thereto, that is, an object to be detected, is placed on a belt 4.
When passing over the excitation coil 5 one after another, the detection coil 7 detects the pulse voltage generated by the alternating current magnetic field generated there, and the measuring device 8 confirms the quantity of each detected object. It is something to know.

[Problem to be solved by the invention]

Although markers using amorphous matrix materials are useful, they still have the following problems. Conventionally, this type of marker uses a thin strip or wire of magnetic material that has the same -8 characteristics, so the presence or absence of the marker can be determined by measuring the detected voltage generated by fluctuations in the research field.

In other words, only the presence or absence and quantity of the articles are known, and the type of the classified articles cannot be recognized. Therefore, it is desirable to be able to use this marker, for example, when classifying and counting a large number of products by type, and therefore it is necessary to further improve the structure and usage of magnetic markers.

The present invention has been made in view of the above points, and its purpose is to provide an identification method that is attached to an article and makes it possible to identify not only the presence or absence of the article but also the article (type). .

[Means to solve the problem]

The magnetic marker detection method of the present invention uses magnetic markers that have different hunting history characteristics depending on the material or shape, and attaches one or more magnetic markers to an object to be detected. The voltage waveforms measured individually or in combination are frequency-analyzed and the detected object is identified as a frequency spectrum.

[Effect]

The magnetic marker detection method according to the present invention uses, as a magnetic marker, at least one thin strip or thin wire of a soft magnetic material having a flux-field hysteresis characteristic (Φ) arranged in parallel in the longitudinal direction. When an external alternating magnetic field is applied to a ribbon or wire, the Φ-H characteristics (coercive force,
The induced electromotive force with different maximum magnetic flux, permeability, and phase can be obtained as a single waveform or a combined waveform, so this waveform can be detected as a frequency scale and the frequency pattern unique to the magnetic marker can be detected by g.
By identifying the magnetic marker, the type of the article can be determined.

〔Example〕

Since the article identification device to which the present invention is applied is the same as that shown in FIG. 6, the explanation will be omitted, and the magnetic marker detection method of the present invention will be described below. FIG. 1 shows a partially cutaway perspective view of a detection element 9 having a magnetic marker 11.
Here, as shown in FIG. 1, the magnetic marker 11 includes, for example, two amorphous magnetic thin wires 1a and lb having soft magnetism.
The detection elements 9 are arranged in parallel to each other and fixed between fixed plates 10 made of thin plastic, for example.
will be explained assuming that it is attached to article 2 in FIG.

For example, Fe-based amorphous magnetic wires are used as the magnetic wires 1a and lb, and the maximum generating flux ΦmaX*Hoda force Hc of la and 1b is Φmaxla>Φmax lb, Hc 1
a (Hc lb) The magnetic hysteresis characteristics of the two are different. This can be determined by the material and shape of the magnetic thin wire. Φ-H of the FB thin wire 1a, lb
The percentage properties are shown in Figure 2 (alt, (bl).

A magnetic thin wire 1a having such Φ and -H characteristics.

The waveform of the induced electromotive force generated in the detection coil 7 due to can reversal in the alternating current magnetic field of 1b and its frequency analysis results are expressed as W, 3
Shown in Figures (a) to (c). Figure 3 (a) shows the AC magnetic field waveform, and the induced electromotive force waveform is W, and as shown in Figure 3 (b), the peak waveform of the induced electromotive force according to the magnetic characteristics of each amorphous magnetic thin wire 1a, lb is It is a complex synthesized waveform. Frequency analysis is performed by discrete Fourier transform, and the sample waveform in a time window that is an integral multiple of the alternating current magnetic field period is subjected to frequency analysis and is expressed as a frequency spectrum included in the induced electromotive force waveform. The result is shown in FIG. 3(c).

FIG. 4(al) and (b) show the second amorphous magnetic wires 1a and lb in the magnetic marker 11.
This is an example of a case where the Φ-H% property is different from that shown in the figure. As shown in Fig. 4(a), 1a has a relatively smooth rotational magnetization reversal region that is almost the same as that in Fig. 2(al). In contrast, as shown in Figure 4 (bl), 1b has a rectangular characteristic in which magnetization is reversed mainly due to domain wall motion, and the magnetization is reversed in an alternating magnetic field for both. The induced electromotive force waveforms generated in the detection coil 7 become separated from each other due to the difference in Hc.This situation is illustrated in Figures 3(a) to (c).
5(a) to (cl).
is the waveform of the induced electromotive force. In this case, the frequency spectrum resulting from the discrete Fourier transform is mainly a spectrum corresponding to each induced electromotive voltage wave, as shown in Figure 5 (C), and the composite synthesis as shown in Figure 3 (C) The low frequency fundamental of the waveform does not appear.

As described above, by obtaining the characteristics of the induced electromotive voltage waveforms generated from a plurality of amorphous magnetic thin wires with different magnetic properties as a unique frequency spectrum pattern, the spectrum string can be identified by pattern recognition, that is, the magnetic marker 1
1 type can be identified.

Although the above description has been made using a plurality of magnetic thin wires, according to the detection method of the present invention, it goes without saying that only one maternal thin wire is used.
Books are also possible. However, when using a single magnetic thin wire, it is necessary to prepare many wires with different magnetic history characteristics, but when using multiple wires, only a combination of these can be used, so the number of types of magnetic thin wires can be reduced. This can be determined depending on the actual situation by carefully considering the type and quantity of the items to be identified.

〔Effect of the invention〕

In detecting a magnetic marker that is attached to an article and used to recognize it, the present invention uses at least one magnetic material with different magnetic hysteresis characteristics as the magnetic marker, and these materials are exposed to an external alternating current field (thereby causing magnetization reversal and The frequency spectrum of the induced electromotive force of each magnetic material generated in the detection coil that detects magnetic flux changes as an induced electromotive force is analyzed by frequency analysis and detected as a unique frequency spectrum of the magnetic marker. It becomes possible to pattern-recognize the rows with a measuring instrument, and as a result, it is possible to effectively identify the magnetic marker, that is, even the type of article.

[Brief explanation of the drawing]

FIG. 1 is a partially exploded perspective view of a detection element having a magnetic marker used in the present invention, and FIGS.
Figure 3 shows the Φ-H characteristic diagram of the magnetic thin wire of the magnetic marker, Figure 3 (ω+) shows the AC magnetic field waveform diagram, and the output waveform generated in the detection coil due to the combination of the Φ-H characteristics in Figure 2. Figure 4. Frequency spectrum diagram obtained by frequency analysis of the output waveform. Figure 4 (a) and (b) show that the magnetic thin wire is the second
Φ-H characteristic diagram of a combination different from that shown in the figure, Fig.
), (bl, and (c) are respectively an alternating current magnetic field waveform diagram, an output waveform diagram generated in the detection coil by a magnetic marker that combines the Φ-H characteristics in Figure 4, a frequency spectrum diagram obtained by frequency analysis of the output waveform, and Figure 6. is a schematic diagram showing the main part configuration of the article identification device, and Figure W!7 is a partially enlarged view of the device shown in Figure 6. 1.11...Magnetic marker 1a, lb...Amorphous magnetic thin wire, 2 ...article, 3...rotating part, 4.
... Belt, 5... Excitation coil, 6... AC oscillator, 7... Detection = illumination, 8... Measuring device, 9... Detection element, 10... Fixing plate. Figure 3 φ φ (a) (b) (b) Figure 4 Shu Langei (b) Figure 7

Claims (1)

[Claims] 1) A magnetic marker detection method that recognizes a detected object by passing the detected object to which a magnetic marker made of a soft magnetic material is attached through an alternating magnetic field, which detects at least one magnetic marker having different magnetic history characteristics for each detected object. Using two magnetic markers, frequency analysis is performed on the voltage waveform output to the detection coil due to magnetic flux changes occurring in each magnetic marker in an alternating magnetic field.
A magnetic marker detection method characterized by identifying an object to be detected as a frequency spectrum.