JPH02290589A - Magnetic marker and device for reading and identifying this marker - Google Patents

Abstract

PURPOSE:To identify not only articles but the kinds of the articles as well by disposing magnetic thin bands, etc., having square magnetic history characteristics and being further different in the magnitude of coercive force and magnetic flux in parallel in the longitudinal directions thereof. CONSTITUTION:First and 2nd exciting coils 9a, 9b are so disposed as to form an L shape with each other when viewed in the plane direction with respect to a belt 4. The belt 4 on which the articles 2 attached with the magnetic markers 1 passes in the coil 9a in an arrow direction and the coil 9b is positioned alongside the belt 4. The coil 9a is connected to a 1st AC oscillator 6 and the coil 9b to the 2nd AC oscillator 6b, respectively. The detecting coils 10a, 10b are disposed respectively on the upper side and lower side of the belt 4 and formed as double coils in order to negate the induced electromotive force by the coils 9a, 9b and are connected to a measuring instrument. An AC rotating magnetic field is generated in a hatched region 11 when an AC current is passed to the coils 9a, 9b. The phases of the AC current to be passed to the coils 9a, 9b are previously shifted by 90 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic marker that is attached to an article to identify the type, quantity, etc. of the article, and a reading and identification device therefor.

[Conventional technology]

It is known that by attaching a marker to an article and reading the marker, it is used to detect the quantity of the article or to prevent the article from being stolen. Conventionally, such markers have been desired to be small and inexpensive. Also, to prevent damage caused intentionally or carelessly,
Since the marker is attached to an item so that it cannot be seen directly, markers that can use magnetism, microwaves, etc. are used. For example, a marker uses an amorphous magnetic ribbon or thin wire to apply a magnetic field, or an aluminum foil is irradiated with microwaves.

In particular, the method of passing an object to be detected to which an amorphous magnetic material is attached as a marker through an alternating magnetic field and detecting the change in magnetic flux that occurs in the amorphous magnetic material takes advantage of the effective soft magnetic properties of the amorphous magnetic material. This method is superior in that there are few restrictions on the position of the marker and the objects to be detected, and that highly sensitive, compact, and lightweight markers can be used.

On the other hand, FIG. 20 shows a schematic diagram of the main part configuration of a conventional magnetic marker reading and identification device for reading and identifying such markers. In FIG. 20, an article 2 to which a magnetic marker 1 in the form of an amorphous ribbon or thin wire is attached is placed on a bevellet 4 stretched between two pulleys 3, and as the belt 4 runs due to the rotation of the pulleys 3, it moves in the direction of the arrow. Moving. The excitation coil 5, AC oscillator 6, detection coil 7, and measuring device 8 are also shown as enlarged views in FIGS. 21(a) and 21(b), respectively. In FIG. 20, an excitation coil 5 that generates an alternating magnetic field is connected to an alternating current oscillator 6, and a detection coil 7 that detects as an induced electromotive voltage the change in magnetic flux accompanying the magnetization reversal of the magnetic marker 1 caused by the alternating magnetic field is a measuring device. 8 is connected. This measuring device 8 has a function of identifying the pulse 'swelling train generated in the detection coil 7 by pattern recognition. The detection coil 7 is a twin coil for canceling the induced electromotive voltage generated in the detection coil 7 itself by the excitation coil 5.

The magnetic marker 1 uses, for example, a plurality of magnetic ribbons or thin wires such as a CO-based amorphous alloy, and these are affixed to the article 2 that is the object to be detected.The magnetic marker 1 is fixed to a plastic material or the like. It is also possible to configure the detection element as a detection target element and attach it to the article 2 for use.

This device has magnetic markers 1 and 1, respectively, as shown in FIG.
When a plurality of articles 2, ie objects to be detected, to which are pasted pass over the excitation coil 5 on the belt 4, the detection coil 7 detects the pulse voltage generated by the alternating magnetic field generated there. , the measuring device 8 identifies the type of each detected object.

[Problem to be solved by the invention]

As mentioned above, markers using amorphous magnetic materials are useful, but the following points still need to be solved.

The first is the identifiability of the marker. Conventionally, this type of marker uses magnetic materials that are all made of ribbons or thin wires with the same magnetic properties, so the voltage generated by the magnetic field can only be measured and obtained based on the presence or absence of the marker, that is, the presence or absence of the article. The problem is that it is not possible to recognize the type of classified goods, only the presence or absence and quantity. Therefore, it is desirable to be able to use this marker when, for example, classifying and counting a large number of identical products by manufacturer, and therefore it is necessary to further improve the structure and usage of the marker.

Second, when the magnetic flux change that occurs in an amorphous magnetic material in an alternating magnetic field is extracted as an induced electromotive force by a detection coil, the faster the magnetic flux change occurs, the faster the detection coil can obtain a steep pulse voltage, which makes it easier to detect the pulse voltage. easy and
This is preferable because it is less susceptible to disturbance magnetic fields. However, in order to cause a rapid change in magnetic flux, the magnetic material used should have a rectangular Φ-Hffl hysteresis characteristic, and in order to maintain this square characteristic, the shape of the magnetic material should be changed so that the demagnetizing field is small. It is necessary to make it happen. That is,
The shape of the marker needs to be sufficiently large in length compared to its width, which results in an increase in the overall size of the marker.

On the other hand, the problem with the conventional magnetic marker reading identification device shown in FIG. 20 lies in the installation state of the excitation coil 5. That is, only one excitation coil 5 is provided below the belt 4 on which the article 2 is placed. The position and direction of the item 2 on which the magnetic marker 1 is attached are not necessarily constant, so when the magnetic marker 1 passes through the alternating current magnetic field area generated by the excitation coil 5, its position or direction changes. The difference causes the output from the detection coil 7 to vary and become unstable.

The present invention has been made in view of the above points, and its purpose is to provide a small magnetic marker configured to be attached to an article so as to enable not only the presence or absence of the article but also the identification (type) of the article. It's about doing.

Another object of the present invention is to provide a magnetic marker reading and identification device that can extract a stable output voltage from a detection coil regardless of the position or direction in which an article to which a magnetic marker is attached is placed. .

[Means to solve the problem]

In order to achieve the above object, the magnetic marker of the present invention has a rectangular magnetic hysteresis characteristic, and has a plurality of magnetic thin strips or thin wires having different coercive force and ffl flux, or stress at the surface and center. Two layers of thin wires with different distributions are arranged in parallel in the longitudinal direction.

In order to achieve the above object, the magnetic marker reading and identification device of the present invention passes an alternating magnetic field through an article to which a magnetic marker is attached while traveling on a belt, and detects a pulse voltage due to a change in magnetic flux generated in the magnetic marker. Excitation coils for generating an alternating magnetic field for a device for identifying articles taken out from detection coils are arranged as follows. That is,
A first excitation coil in which the magnetic marker passes through the center hole together with the belt, and a second excitation coil located on one side of the belt and forming an L-shape with respect to the first excitation coil,
Alternatively, two pairs of the first and second excitation coils are used, and the first excitation coils and the second excitation coils are both arranged to face each other.

[Effect]

The magnetic marker of the present invention is made by arranging a plurality of thin strips or thin wires of magnetic material having square ΦH% characteristics, or thin wires consisting of two layers with different stress distributions at the surface and center in parallel in the longitudinal direction. The magnetic materials arranged in parallel have different coercive force values, and the maximum magnetic flux generated in each row of magnetic markers by applying an alternating magnetic field is made to have a different value by changing the cross-sectional area. Therefore, when an external magnetic field is applied, the phase of magnetization reversal and the amount of change in magnetic flux differ for each row, and each row is obtained as a unique pulse voltage train. By pattern recognition of these voltage trains with a measuring instrument, the type of marker can be determined. can be judged.

In addition, by applying a wire drawing process to a thin wire with high magnetostriction,
By using a two-layer structure with compressive stress on the surface and tensile stress on the center, the magnetic flux reversal limit magnetic field is increased in an alternating magnetic field, and rapid magnetization reversal is performed, with less influence from demagnetizing fields. Therefore, such magnetic wires can be relatively short, and the marker can be made more compact.

In the magnetic marker reading identification device of the present invention, two or more excitation coils are used, and the phase of the alternating current flowing through the excitation coils is set to 9.
Since the magnetic markers are shifted by 0', a rotating magnetic field that is a combination of an alternating current magnetic field parallel to the traveling direction of the magnetic marker and an alternating current magnetic field perpendicular to the traveling direction of the magnetic marker can be applied to the magnetic marker. Therefore, even if the position or direction of the article to which the magnetic marker is attached differs, the alternating current magnetic field also acts in the longitudinal direction of the magnetic marker at least once, resulting in a stable output without causing variations in the pulse voltage obtained. is detected.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a schematic partial perspective view showing the arrangement row of excitation coils of a magnetic marker reading identification device according to the present invention, and the same parts as in FIG. 20 are indicated by the same numbers. In FIG. 1, two excitation coils are provided, the first excitation coil 9
The excitation coil a and the second excitation coil 9b are arranged so as to form an L-shape with respect to the belt 4 when viewed in a plan direction. The belt 4 carrying the article 2 to which the magnetic marker 1 is attached passes through the first excitation coil 9a in the direction of the arrow, and the second excitation coil 9b is located on which side of the belt 4. The first excitation coil 9a is connected to the first AC oscillator 6a, and the second excitation coil 9b is connected to the first AC oscillator 6a.
are connected to the second AC oscillator 6b, respectively. The detection coils 10a and 10b are arranged above and below the belt 4, respectively, and are twin coils in order to cancel the induced electromotive force caused by the first excitation coil 9a and the second excitation coil 9b. Then, they are each connected to a measuring device 8.

When an alternating current is applied to the two excitation coils 9a and 9b in this state, an alternating current rotating magnetic field is generated in the shaded area 11. At this time, the first excitation coil 9a and the second excitation coil 9
The phases of the alternating currents flowing through the electrodes b are shifted by 90 degrees from each other, and the waveforms of these alternating current magnetic fields are shown in FIG. FIG. 2(A) shows the alternating current magnetic field waveform caused by the first exciting coil 9a, and FIG. 2(B) shows the alternating current magnetic field waveform caused by the second exciting coil 9b, and in both cases, the vertical axis represents the magnetic field strength. The horizontal axis is time. Therefore, when the magnetic marker 1 passes through the alternating current rotating magnetic field generating region 11, the alternating magnetic field applied to the magnetic marker 1 is the sum of the alternating magnetic fields shown in FIGS. 2(A) and 2(B). In this case, the AC magnetic field generated by the first excitation coil 9a is applied parallel to the traveling direction of the magnetic marker 1, and the AC magnetic field generated by the second excitation coil 9b is applied perpendicular to the traveling direction of the magnetic marker 1. . Therefore, when the AC magnetic field applied to the magnetic marker 1 at times a, b, c, d, and e shown in FIGS. 2(A) and 2(B) is expressed as a vector, it becomes as shown in FIG. 3. The AC magnetic field generated by the first excitation coil 9a and the second excitation coil 9b is combined to form a rotating magnetic field. In the arrangement of the two excitation coils according to the present invention, while the magnetic marker 1 passes through the alternating current rotating magnetic field generating region 11, the period T of the rotating magnetic field is at least 1 or more, that is, the alternating magnetic field rotates once. Adjust the speed of the belt 4 as follows. If the starting point of the AC magnetic field vector in Figure 3 is aligned with the center point of the magnetic marker 1, and the time change in the direction and intensity of the AC magnetic field at that point is expressed by the magnitude of the vector, the result will be as shown in Figure 4. , the dotted line represents the alternating current rotating magnetic field. a, b, c, d in Figure 4,
e are times a, b, and in Figures 2 and 3, respectively.
This corresponds to c, d, and e. FIG. 5 illustrates the positional relationship when the longitudinal direction of the magnetic marker 1 attached to the article 2, that is, the direction of the arrow, is not parallel to the traveling direction of the belt 4. In either case, as the magnetic marker 1 passes through the alternating current rotating magnetic field generating region 11, an alternating magnetic field can be applied at least once in the longitudinal direction of the magnetic marker 1, so that the magnetic marker 1 made of an amorphous magnetic material etc. It becomes possible to effectively generate a pulse voltage generated by a change in magnetic flux in the longitudinal direction of the detection coils 10a and 10b shown in FIG.
Therefore, stable output can be detected from As mentioned above, the detection coils 10a and 105 are twin coils, but they are arranged at different distances from the magnetic marker 1, in other words, the belt 4. It consists of a magnetic marker 1 and detection coils 10a, 10.
This is because if they are equidistant from each other, pulse voltages caused by changes in the magnetic flux of the magnetic marker 1 are canceled out. Then, before the magnetic marker 1 enters the alternating current rotating magnetic field generating region 11, the induced voltage generated in the detection coils 10a and 10b is adjusted to O by the first excitation coil 9a and the second excitation coil 9b. put.

FIG. 6 is a perspective view schematically showing the arrangement of the excitation coils when four excitation coils are provided. Although the detection coil is not shown, the belt 4 is similar to the embodiment shown in FIG. placed above and below. That is, in FIG. 6, there are two coils corresponding to the first excitation coil 9a through which the belt 4 shown in FIG. The first excitation coil 9 is formed by using two pieces corresponding to the second excitation coil 9b that is L-shaped.
Four excitation coils are arranged such that the second excitation coils 9b face each other and the second excitation coils 9b face each other. As shown in FIG. 6, when a pair of first excitation coil 9a and second excitation coil 9b are combined, the alternating current rotating magnetic field generating region, not shown in FIG. The spread of the magnetic flux is smaller than in the illustrated region 11, and parallel magnetic fields in two directions are applied reliably and uniformly to generate a uniform rotating magnetic field over the entire region. As a result, the magnetic marker 1 is magnetized uniformly no matter where it is placed in the width direction of the belt 4, and an extremely stable pulse voltage can be detected from the detection coil (not shown). It becomes possible.

Next, the structure and function of the magnetic marker of the present invention will be described.

FIG. 7 shows a partially cutaway perspective view of the detected element 20 having the magnetic marker 1, (a) and (b).
, (C). Both la,
1b is a magnetic ribbon whose Φ-H curve is shown in FIG.

The following description will be made with reference to FIGS. 7 and 8.

In FIG. 7, two magnetic thin strips 1a and lb are arranged at regular intervals in the longitudinal direction and fixed between fixing plates 9 made of thin plastic, for example, to form a detected element 20. . The magnetic ribbons 1a and lb have a length of, for example, about 50 fl. For each detected element 20, in FIG. 7(a), the width dimensions of the magnetic ribbons 1a and 1b are the same as 2B, and in FIG. 7(b), the cross-sectional area of 1b is Figure 7 (C
), the cross-sectional area of 1a is set to be 1.5 times the cross-sectional area of 1b.

The magnetic ribbons 1a and lb have a rectangular shape Φ-H characteristic, and are made of a material with excellent other magnetic properties, such as a CO-based amorphous alloy, and la and lb each have a coercive force. Hc
need to be different.

When using materials with the same saturation magnetic flux density, the maximum magnetic fluxes are made different by changing the cross-sectional area of either one of the ribbons 1a and lb. That is, FIG. 7(b)
This is the case of (C). Φ of these ribbons 1a and lb
The 1H curve is expressed as A-1 and A-2 for 13, and B-1 and B-2 for 1b, and the combinations thereof are shown in FIG. That is, in FIG. 8, in the case of FIG. 7(a), since the cross-sectional areas of the ribbons 1a and 1b are the same, the magnetic flux Φ of A-1 and B-1 and the hysteresis characteristic of the magnetic field H are the same maximum magnetic flux. shows. In the case of FIG. 7(b), the cross-sectional area of the ribbon 1b is 1.5 times that of the ribbon 1a, so the Φ-H characteristic in FIG. 8 is a combination of A-1 and B-2.

In Fig. 7(C), the cross-sectional area of the ribbon 1a is 1.5 of that of the ribbon 1b.
The Φ-H characteristic in FIG. 8 is a combination of A-2 and B-1.

Next, a pulse voltage train generated in the detection coil 10 when the article 2 to which the magnetic marker 1 as described above is attached is passed through an alternating current magnetic field by the above-mentioned magnetic marker reading and identification device will be described. FIG. 9 shows the AC waveform and the pulse output at each detected element 20 in FIG.
The pulse output of a is expressed as AI, and the pulse output of the ribbon 1b is expressed as B weight. Figure 9 (a), (b), (
C) shows a time-series pulse voltage train generated in the detection coil 10 according to the order of magnetization reversal corresponding to the difference in coercive force of each ribbon, and these are the same as those of the detected element 20 in FIG. This is obtained from (a), (b), and (C). That is, it can be seen that a pulse output corresponding to the magnetic flux change of the Φ-H characteristic shown in FIG. 8 can be obtained by the combination of the ribbons 1a and lb.

Here, a method for recognizing pulse voltage trains will be described.

When the detected element 20 having the marker 1 passes through an alternating current magnetic field, in practice, the marker 1 does not always face the same direction with respect to the alternating magnetic field.

The pulse output level detected by the detection coil 10 depends on the vector component of the alternating current magnetic field in the longitudinal direction of the marker 1, so there is a high possibility that the output level will be different each time the marker 1 passes through the alternating magnetic field. It becomes difficult to identify the pulse voltage train in the output level state. Therefore, when using the conventional magnetic marker reading identification device, this problem can be solved as follows. The first method is to change the pulse voltage train to the mutual output level (As, Bt in Figure 9).
It is identified through relative comparison.

For example, the first output (As)t expressed in time series,
The nth output (At)n,(B,)s is the reference
Bt)n as (As)n/(AI)1t(Bt
)n/(Bt)t.

According to this method, it is possible to pattern the pulse voltage train without being influenced by the direction of the magnetic marker. The second method is to integrate the pulse voltage train, ie, dΦ/dt. By integrating the pulse voltage 6 oc dΦ/di, a pattern as shown in FIG. 10 can be obtained in time series. FIGS. 10(a), (b), and (C) are shown as integral processing of the pulse voltages in FIGS. 9(a), (b), and (C), respectively. In the first dimensionless processing method, the pulse voltage train is digitized and identified, whereas in the second integral processing method, changes in Φ accompanying the process of increasing or decreasing are identified as a pattern. However, in this case as well, the direction of the marker relative to the external alternating magnetic field can be determined by making the second, third, ... n-th integral values dimensionless based on the first integral value. A stable pattern can be obtained for each type marker without being affected.

The above-mentioned identification process is unnecessary in the magnetic marker reading identification device using an alternating current rotating magnetic field according to the present invention.

Two types of ribbons with different coercive forces, 1a and lb, are used as markers, and the cross-sectional area of these strips is changed to detect the detected element 10.
The magnetic marker of the present invention increases the number of magnetic thin strips with different coercive forces and further changes the cross-sectional area of these strips. The number of identification types can be increased.

This is shown in Figures 7, 8, and 9, and Figures 11 and 1.
2 and 13, and the same reference numerals are used to facilitate comparison with the previous figure. However, regarding the shape of the magnetic ribbon, magnetic hysteresis, and pulse output, in Figure 11, the magnetic marker 1 has increased IC so that it consists of three magnetic ribbons, and in Figure 12, it is C-t, c. -2, C in Figure 13
,,C, are added.

Figure 11 shows three magnetic ribbons la and l with different coercive forces.
This figure shows an element 20 to be detected in which a magnetic marker 1 consisting of B, LC is fixed to a fixing plate 19. In this case, by creating a combination of each magnetic ribbon with a cross-sectional area 1.5 times larger, seven types of magnetic markers can be obtained from FIG. 11(a) to FIG. 11(g) in the order of symbols. Table 1 shows the combinations based on the cross-sectional area ratio.

Table 1, Figure 12 is a Φ-H diagram showing changes in magnetic flux due to differences in cross-sectional area.
, B-1 and B-2 for the ribbon No. 1b, and C-1 and C-2 for the ribbon IC. Table 2 shows the combinations of Φ-H characteristics.

Similarly to FIG. 9, FIG. 13 also shows the pulse output of each ribbon, and seven types of patterns from (a) to (g) can be obtained based on the combination of FIGS. 11 and 12.

As described above, a magnetic marker consisting of a plurality of magnetic ribbons with different coercive forces Hc but the same saturation magnetic flux density Bs can be created by changing the cross-sectional area between the ribbons, that is, by setting the amount of change in magnetic flux. The characteristics of the pulse voltage train pattern unique to the marker can be determined, making it possible to easily identify the article.

Furthermore, the magnetic marker of the present invention has a coercive force Hc from the beginning,
It is also possible to make a magnetic marker using a plurality of magnetic materials having mutually different saturation magnetic flux densities Bs. An example of this is shown in FIG. 14 as the Φ-H diagram and pulse output pattern of three magnetic materials D, E, and F, as in the previous figures. In this case, since each magnetic material has a different pulse voltage level depending on the saturation magnetic flux density B8 of each magnetic material, it can effectively function as an identification marker even if the cross-sectional area is the same. For example, it is possible to obtain the desired magnetic properties of CO-based amorphous magnetic alloys by appropriately selecting the material composition and heat treatment conditions. If a mutual difference cannot be obtained, by changing the cross-sectional area at the same time, a pulse voltage train sufficient for pattern recognition can be obtained.

In addition, when a Co-based amorphous alloy ribbon has a shape, especially one in which the length is not very large compared to the width, the permeability decreases due to the demagnetizing field when magnetized, and the magnetization reverses. The speed will be slower. In this case, since the usual rectangular M-H curve described above cannot be obtained, by appropriately selecting the material composition and heat treatment, the Φ-H characteristic shown in FIG. 15 can be imparted. 15th
The figure shows the Φ-H diagram and pulse output pattern for ribbon materials L, M, and N. Depending on the length/width of the ribbon material, pulses can be generated using such magnetic flux jump characteristics. It is possible to generate the magnetic marker, and it is possible to obtain the same effect as a magnetic marker having a normal rectangular magnetic hysteresis characteristic.

Above, we have described an example of setting ribbons having different amounts of magnetic flux change by selecting the cross-sectional area or saturation magnetic flux density of a plurality of magnetic materials with different coercive forces for the magnetic marker of the present invention. Another possible method is to increase the cross-sectional area by increasing the number of rows used.

However, when a single thin ribbon is formed from a plurality of strips, even though they have the same magnetic properties, there is a possibility that the sharp magnetization reversal of the square jff-H characteristics may be slightly shifted over time. As a result, the pulse voltage appears as a time-series deviation, causing an error in pattern recognition. Therefore, as previously stated, it is desirable that the ribbon be taken from the same material for each marker, with only the cross-sectional area varying.

When using the magnetic marker of the present invention, if noise occurs in the pulse voltage train, the pulse voltage train will be detected for at least several cycles while the magnetic marker passes through the detection band of the AC magnetic field. , and by averaging them, error factors caused by noise can be removed. Although the pulse voltage train has been described so far as being detected by the detection coil 10, a highly sensitive magnetic field sensor can also be used as another means for detecting changes in leakage magnetic flux generated from the magnetic marker 1. When detecting with a magnetic field sensor, a differential type is used to remove the influence of alternating magnetic fields.1 Therefore, the detection output is the same as the above-mentioned integral processing method.
It becomes step-like as shown in the figure.

The magnetic material forming the magnetic marker of the present invention has a different coercive force and has a square g-H% property, and the jitter of the detected pulse voltage is small, making it possible to detect and identify the pulse voltage in time series. However, the aforementioned Co-based amorphous alloy has excellent magnetic properties and high corrosion resistance, and has the advantage that the detection output is less affected by external stress due to its low magnetostriction. Regarding the shape of the attached magnetic marker, it is suitable to use a thin strip in terms of output sensitivity and environmental resistance. Of course, in addition to the thin strips described above, thin wires can also be used.

Furthermore, when using a magnetic thin wire for a magnetic marker, in addition to CO-based amorphous alloy, the shape of the magnetic marker is made smaller by using a pulse voltage caused by the extremely steep magnetization reversal 1 of a high magnetostrictive Fe-based amorphous alloy wire. You can also
The case where this magnetic thin wire is used as a marker material will be explained below.

Amorphous magnetic fine wires are usually produced by spinning in a rotating liquid, and the standard wire diameter is about 130 μm.

This is because strong compressive stress and torsional stress remain on the surface during ultra-rapid solidification. This property is particularly easy to obtain with re-based amorphous thin wires that have high material strength and a large magnetostriction constant. Furthermore, this Fe-based amorphous thin wire can be made into a thin wire with a two-layer stress structure in which the front layer and the core portion have significantly different stress distributions by drawing and subsequent heat treatment under tension.

When such amorphous magnetic thin wire is used as a magnetic marker, strong tension exists in the core near the center.
The energy density of the domain wall becomes high, and as a result, the magnetic flux reversal limit magnetic field He becomes large, a large Barkhausen effect occurs at the time of magnetic flux reversal, and a steep pulse pressure is obtained in the detection coil.

By the way, the speed of lil1 flux reversal is affected by the demagnetizing field determined by the shape of the magnetic material, so in order to rapidly reverse the magnetic flux, the wire diameter of the amorphous thin wire should be 1 as described above.
Although the magnetic marker is small at 30 μm, it requires a sufficiently large length of 7 cm or more, resulting in an increase in the overall size of the magnetic marker. However, as mentioned above, by making the large Parkhausen effect noticeable by the stress structure inside the amorphous wire, H'' −Ho≧H
d. (However, HO is the domain wall displacement limit) is more likely to hold true, and rapid magnetic flux reversal due to the large Parkhausen effect can become dominant. As a result, even if the amorphous thin wire has a relatively short length of 2 to 3 cm, it is possible to obtain a steep induced pulse voltage. This is because strong compressive stress is applied to the surface layer by the drawing process of the Fe-based amorphous magnetic thin wire and subsequent heat treatment in a magnetic field under tension, which induces axial magnetic anisotropy in the core part. This is because the random stress introduced at the same time as the wire drawing process can be removed to clarify the magnetic flux reversal limit magnetic field H'', resulting in a remarkable large Barkhausen effect.

For comparison, the ultra-quenched state (a) and the two-layer stress structure after processing and heat treatment (b) are shown. FIG. 17 shows a partial cutaway of a detected element 20A in which a magnetic marker IA, which has a two-layer stress structure and combines amorphous magnetic wires 1d, le, and if with different magnetic flux reversal limit magnetic fields Hz, is installed on a fixed plate 19A. It shows a perspective view. These magnetic thin wires 1d,
The lengths of le and if are both 30 m. The Φ-H% characteristics of these are shown in FIG. Magnetic wire 1d, le
,if can be changed by changing the wire drawing rate and heat treatment conditions.
The magnetic flux reversal limit magnetic field H゜ and the saturation magnetic flux Φmax can be made different from each other. FIG. 19 shows the pulse voltage detected by the detection coil 10 using the AC magnetic field waveform generated by the excitation coil and the magnetic marker I shown in FIG. 17, which corresponds to each magnetic thin wire 1d, le, and if. For convenience, the same symbols are used here to represent the outputs. As already mentioned, the pulse voltage train detected by the detection coil 10 is subjected to signal processing such as ld/ld, te/le, if/if, etc. by the measuring device 8 to form a pattern to identify the type of person using the magnetic marker I. The same is true for thin strips.

In addition, in a magnetic marker I using multiple magnetic thin wires with a two-layer stress structure, several combinations are possible by changing the magnetic flux reversal limit magnetic field H'' and the magnetic flux size depending on the cross-sectional area for each magnetic thin wire. However, this point can be handled in the same way as the case of the magnetic marker 1 using the thin ribbon described above, so the explanation thereof will be omitted.When using the amorphous magnetic thin wire as described above, It is possible to construct an @ki marker to identify the item.

〔Effect of the invention〕

Conventionally, magnetic markers with an article number attached and used to recognize this were made of magnetic materials with the same characteristics and could only detect the presence or absence of the article or the quantity. is the square 1B-H characteristic. Since a plurality of thin strips or thin wires of magnetic material having mutually different coercive forces and saturation magnetic fluxes are arranged in parallel in the longitudinal direction, when their magnetization is reversed by an external magnetic field,
Magnetic flux changes corresponding to a plurality of magnetization reversals in time series can be detected as a pulse voltage train by the detection coil. After signal processing of this pulse voltage train, it is possible to perform pattern recognition using a measuring instrument. As a result, even the type of magnetic marker, that is, the article, can be effectively identified. Furthermore, when using magnetic thin wires, we apply appropriate processing and heat treatment to create a two-layer structure with significantly different stress states, with strong compressive stress on the surface and strong tension in the center, resulting in axial magnetic anisotropy, resulting in magnetic flux reversal. By increasing the critical magnetic field H'', this magnetic thin wire is controlled by rapid magnetization reversal based on the large Barkhausen effect rather than the demagnetizing field effect depending on the shape of the magnetic marker, so the length becomes relatively short. A short, compact and highly sensitive magnetic marker can be obtained.

Further, in the magnetic marker reading and identification device according to the present invention, a plurality of excitation coils are arranged to generate a rotating AC magnetic field, and an effective AC magnetic field is applied to the magnetic marker regardless of its position or direction while traveling. As a result, there is no variation in the pulse voltage generated due to the leakage magnetic flux of magnetic markers such as amorphous magnetic materials, making it possible to stably detect the output and identify the type and quantity of items with higher accuracy. This is possible.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the magnetic marker reading and identification device according to the present invention, and FIG.
B) is an AC magnetic field waveform diagram generated by two excitation coils, Figure 3 is an AC magnetic field vector diagram at each point in time, Figure 4 is an AC magnetic field vector diagram with the starting points coincident, and Figure 5 is a diagram showing magnetic markers. FIG. 6 is a schematic diagram illustrating the positional relationship of attached articles, FIG. 6 is a schematic perspective view illustrating an example of the arrangement of excitation coils in another embodiment of the magnetic marker reading and identification device according to the present invention, and FIG. FIG. 8 is a partially cutaway perspective view of a detected element having a magnetic marker of the present invention made of two magnetic thin strips. FIG. 8 is a Φ-H diagram of the magnetic thin strip in FIG.
The figure also shows a voltage one-hour diagram representing the pulse voltage train generated in the detection coil, FIG. 10 shows a one-hour diagram of the integral value of the pulse voltage, and FIG. 11 shows a magnetic marker of the present invention consisting of three magnetic ribbons. FIG. 12 is a Φ-H diagram of the magnetic ribbon in FIG. 11; FIG. 13 is a voltage one-hour diagram showing the pulse voltage train generated in the detection coil; FIG. 14 is a partially cutaway perspective view of the detected element. The figure shows each Φ-H diagram of a magnetic marker using three magnetic materials with different coercive force and saturation magnetic flux, and a one-hour diagram of the pulse output generated in the detection coil. Figure 15 also shows a magnetic ribbon having magnetic flux jump characteristics. The Φ-H diagram and the pulse output one-hour diagram, Figure 16 shows the processing and heat treatment of a magnetic thin wire with a two-layer stress structure! Jn-H characteristic diagrams before and after processing, FIG. 17 is a partially cutaway perspective view of a detected element having a magnetic marker of the present invention made of magnetic thin wire with a two-layer stress structure, and FIG. 18 is the magnetic thin wire of FIG. 17. Φ-H diagram of , FIG. 19 is a one-hour diagram of the pulse output generated in the detection coil, FIG.
It is a partially enlarged view of the apparatus shown in the figure. 1, IA: Magnetic marker 1a, lb, lc:
ffl thin strip, ld, le, If: a thin wire, 2: article, 4: belt, 5.9a, 9b: excitation coil, 6, 6
a, 6b: AC oscillator, 7, 10a, 10b: detection coil, 8: measuring instrument, 19, 19A: fixed plate, 20.20
A: Element to be detected, 11: AC rotating magnetic field generation region. α l) c Be e 4th Senei 5 Sen qb Jizu High 7 Figure A-1 B-1 A-2 B-Z Kuzu 25 Kuzu qguchi A-1 A-2 B-2 'f1tz Ku p ε Fig. 14 C-+ C-Z F L M N (α) /A-gold marker (b-t 1i If

Claims (1)

[Claims] 1) A plurality of magnetic markers attached to an object to be detected passing through an alternating magnetic field, each having a rectangular magnetic hysteresis characteristic or a magnetic flux jump characteristic, each having a different coercive force and magnetic flux size. A magnetic marker characterized in that magnetic thin strips or thin magnetic wires are arranged in parallel in the longitudinal direction at predetermined intervals. 2) The magnetic marker according to claim 1, wherein the magnetic wire has a concentric two-layer stress structure with a compressive stress in the surface layer and a tensile stress in the center, and different stress distributions. 3) An article in which a plurality of magnetic ribbons or thin wires are used as magnetic markers and are attached in parallel in the longitudinal direction is placed on a belt and passed through an alternating magnetic field while running, and a pulse voltage is generated due to changes in the magnetic flux generated in the magnetic markers. an excitation coil for generating the alternating magnetic field of a device for detecting and identifying the article; a first excitation coil through which the magnetic marker passes together with the belt; and a second excitation coil arranged in an L-shape with respect to the first excitation coil. 4) In the apparatus according to claim 3, two pairs of the first excitation coil and the second excitation coil are combined, so that the first excitation coils are connected to each other and the second excitation coils are connected to each other. A magnetic marker reading identification device characterized in that magnetic marker reading and identification devices are arranged facing each other.