JPH064726A - Magnetic marker for article discrimination - Google Patents

Abstract

PURPOSE:To prevent the degradation of detection precision by making one set of plural magnetic thin wires having the same coercive force and arranging plural sets of magnetic thin wires, which are different in coersive forces, in parallel with the direction of an applied magnetic field. CONSTITUTION:Three pairs of magnetic thin wires, namely, six thin wires in total are attached on a fixed plate 12 made of plastics or the like. That is, the coersive force of the pair of magnetic thin wires 2a1 and 2a2 is H1, and that of magnetic thin wires 2b1 and 2b2 is H2, and that of magnetic thin wires 2c1 and 2c2 is H3, and these three pairs of magnetic thin wires are arranged at proper intervals. Therefore, an induced voltage from a detecting coil due to the change of the magnetic flux of magnetic thin wires is increased several times in comparison with the individual use of magnetic thin wires whose coersive forces are different from one another. Thus, the distance between a magnetic marker and the detecting coil can be made long, and the detection precision of article discrimination is not degraded even if the length of magnetic thin wires is limited by the size of an article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic marker attached to an article to identify the type and quantity of the article.

[0002]

2. Description of the Related Art There is known a method in which an article having a magnetic marker is passed through an alternating magnetic field, an induced voltage due to a magnetic flux generated in the magnetic marker is detected by a coil, and the type and quantity of the article are identified. FIG. 9 is a schematic view showing an example of the main configuration of an article identification device using a magnetic marker. In FIG. 9, an article 3 to which a magnetic marker 1 having a magnetic wire 2 is attached is on a belt 5 stretched between two pulleys 4, and the article 3 runs along with the magnetic marker 1 by a rotation of the pulley 4 and a belt 5. Move up in the direction of the arrow. Two exciting coils 6 are arranged so as to sandwich the belt 5 from both sides while the belt 5 is running, and these exciting coils 6 are connected to an AC power supply 7. A plurality of detection coils 8 provided in the vicinity of the belt 5 sandwiched between the two exciting coils 6
Is connected to the measuring instrument 9.

In this way, the belt 5 together with the article 3
Since the magnetic flux of the magnetic marker 1 traveling above changes due to the alternating magnetic field generated from the exciting coil 6, this device takes out the change of the magnetic flux as an induced voltage generated in the detection coil 8, and measures it. The personal computer 10 connected to is used for processing to identify the article 3.

Next, the magnetic marker 1 used here will be outlined. For the magnetic marker 1, it is suitable to use a thin wire of an amorphous magnetic alloy having a square magnetic hysteresis curve and a large Barkhausen effect. The magnetic marker 1 is formed by arranging a plurality of such magnetic fine wires 2 having different coercive forces in parallel in parallel with the magnetic field direction, and the magnetic fine wires 2 can be directly attached to the article 3 for use.
For example, it is general that a plurality of plastic plates or the like are fixed and the base plate is attached to the article 3 for use. When each magnetic wire 2 travels on the belt 5 together with the article 3 and passes through the AC magnetic field band, the magnetic flux is rapidly reversed at the time when the magnetic field generated by the exciting coil 6 reaches the coercive force value.
A pulsed voltage is induced in the detection coil 8. The type and quantity of the article 3 can be identified from this induced voltage.

FIG. 10 is a magnetic hysteresis curve diagram showing the relationship between coercive force and magnetic flux density for the magnetic wire 2 used in the magnetic marker 1. In FIG. 10, the coercive force is H ₁ , H ₂ ,
The magnetic hysteresis curves of three types of H ₃ magnetic thin wires 2a, 2b, 2c are shown. The magnetic fine wires 2 used for the magnetic marker 1 can increase the number of articles to be identified as more magnetic fine wires 2 having different coercive forces are used, but here, for convenience of explanation, the coercive force is three.

These magnetic fine wires 2a having three types of coercive force,
2b and 2c are the maximum value of the triangular magnetic field AC + H_m,-
H_mFig. 11 shows the relationship of the induced voltage generated when excited by
Show. The alternating magnetic field waveform is shown by the dotted line in FIG.
The horizontal axis represents time, and the vertical axis represents the magnitude of magnetic field and induced voltage.
You FIG. 11 shows time t₁Induced voltage e₁Is the coercive force H
₁Magnetic thin wire 2a at time t₂Induced voltage e
₂Is the coercive force H₂Magnetic thin wire 2b of₃
Induced voltage e₃Is the coercive force H₃Magnetic thin wire 2c
Which indicates that. That is, referring again to FIG.
And the coercive force is H₁, H₂, H₃3 magnetic thin
The magnetic marker 1 having the lines 2a, 2b, 2c is the excitation coil.
H when passing through the AC magnetic field band due to₁~ H₃To
Corresponding time t₁~ T₃The magnetic flux suddenly reverses at
A pulsed voltage is induced in the coil 8 and its maximum value is
e₁, E₂, E₃Then, the induced voltage is processed by the measuring instrument 9.
It is possible to identify the article 3 by
It

[0007]

As described above, a method of efficiently identifying various types and a large number of articles 3 using the magnetic marker 1 is useful, but the following points must be solved. It is a matter of course that the higher the detection accuracy is, the better the identification of the article 3 using the magnetic marker 1 is. However, if the article can be detected even if the distance between the magnetic marker 1 and the detection coil 8 is long to some extent, various articles 3 can be detected. The scope of application can be expanded. For that purpose, it is necessary that the induced voltage due to the magnetic flux change of the magnetic thin wire 2 used for the magnetic marker 1 is large. This induced voltage basically increases as the diameter of the magnetic thin wire 2 increases and the length increases. On the other hand, the magnetic marker 1 attached to the article 3 to be identified is restricted in its length depending on the shape and size of the article 3. Therefore, when it is necessary to shorten the magnetic marker 1,
That is, when the magnetic thin wire 2 is shortened, the induced voltage becomes small and the detection accuracy decreases.
There is a problem that the distance between the detection coil 8 and the detection coil 8 cannot be increased.

The present invention has been made in view of the above points, and an object thereof is to provide a magnetic marker for identifying an article which does not deteriorate the detection accuracy even if the magnetic thin wire is shortened depending on the shape and size of the article. To provide.

[0009]

In order to solve the above-mentioned problems, the magnetic marker for article identification of the present invention is constructed as follows. A set of magnetic fine wires with the same coercive force is set, and a plurality of sets with different coercive force of the magnetic fine wires are arranged in parallel between each pair in parallel with the direction of the applied magnetic field. However, strictly speaking, the coercive force may differ slightly depending on the sampling point.For such magnetic fine wires, a plurality of magnetic fine wires with slightly different coercive forces are set as a set, and the magnetic fine wire is Multiple sets of magnetic coercive force that differ greatly are arranged in parallel in parallel with the direction of the applied magnetic field, and the lengths of multiple magnetic wires belonging to each pair are changed, or a part of the magnetic wires belonging to each pair is changed. Array with an angle to the direction of the applied magnetic field,
Make the coercive force of each magnetic wire the same.

[0010]

Since the magnetic marker for identifying articles according to the present invention is configured as described above, the induced voltage from the detection coil due to the change in the magnetic flux of the magnetic thin wire is obtained by simply using magnetic thin wires having different coercive forces one by one. Since it is several times larger than that of the product, it is possible to increase the distance between the magnetic marker and the detection coil, and even when the length of the magnetic thin wire is restricted by the size of the product, the detection accuracy of the product identification is improved. The range of application of the article identification device using this magnetic marker can be expanded without lowering. Furthermore, for a slight difference in coercive force between a plurality of magnetic thin wires taken from the same wire, the apparent coercive force of the other magnetic thin wire changes due to the magnetic flux from one of the adjacent magnetic thin wires. In order to prevent the voltage from being generated separately, the length of the pair of magnetic wires is changed to match the coercive force value, or the magnetic wires are angled with respect to the magnetic field direction. The same effect as described above can be obtained by making the pulse voltage induction times coincide with each other.

[0011]

EXAMPLES The present invention will be described below based on examples. Figure 1
Is the magnetic marker of the present invention11It is a schematic diagram showing the configuration of
It Figure 1 shows a magnetic marker11Is a view from above.
On a fixed plate 12 such as a plastic stick, two as a set
Three sets, a total of six magnetic wires are attached. Immediately
Then, the coercive force of the magnetic wire in each pair is equal to that of the magnetic wire 2a. ₁
And 2a₂Each is H₁, Magnetic wire 2b₁And 2b₂Gazo
Each H₂, And magnetic wire 2c₁And 2c₂Respectively
H₃And place these three sets with proper spacing
is there. Here, there are 3 types of coercive force and 2 types are 1 set.
The reason why the magnetic fine wire is is that the coercive force is three types in the above description.
I did so, so I copied it. Also, the same coercive force
The greater the number of magnetic thin wires, the greater the induced voltage.
Since it can be done, it may be decided depending on the usage conditions, but here
Then, in order to simplify the explanation, each pair has two. This porcelain
Qi marker11The article identification device used for is shown in FIG.
Since it is the same as what was done, the explanation is omitted.

FIG. 2 shows the magnetic marker 11 of FIG.
Maximum value of AC triangular wave + H _m , -H same as shown in
FIG. 9 is a voltage waveform diagram induced in the detection coil 8 when magnetized in the length direction by _m (not shown). As shown in FIG. 2, in the set of the magnetic wires 2a ₁ and 2a ₂ having the coercive force H ₁ , the pulsed voltage having the maximum value e ₁₀ is induced at the time t ₁ . Similarly, the set of magnetic fine wires 2b ₁ and 2b ₂ having coercive force H ₂ is
_The maximum value of the pulsed voltage induced at time t ₃ is e ₃₀ in the set of the magnetic wires 2c ₁ and 2c _{2 having} the coercive force H ₃ when the pulsed voltage having the maximum value e ₂₀ is induced at ₂ . The maximum values e ₁₀ , e ₂₀ , e ₃₀ of the induced voltage are the maximum value e of the induced voltage in the case of one magnetic thin wire of FIG. 11 when compared with the result of FIG. 11.
_It can be seen that it is about twice as large as that of ₁ , e ₂ and e ₃ . It goes without saying that the maximum value of the induced voltage is tripled when the magnetic thin wires are set to three.

The above results are obtained when the coercive force of two magnetic thin wires in a set is completely the same. However, in reality, coercive force may be slightly different from each other even if materials obtained from the same wire are used for the materials of the magnetic fine wires. In this case, when the magnetic marker 11 having the configuration shown in FIG. 1 is excited, the effective magnetic field of one magnetic thin wire in the set changes due to the magnetic flux generated in the other magnetic thin wire, and the apparent magnetic field is maintained. The difference in magnetic force is increased. This phenomenon will be referred to as magnetic mutual interference here. FIG. 3 is a waveform diagram of an induced voltage when magnetic mutual interference occurs. When magnetic mutual interference occurs, as shown in FIG. 3, the induced voltage is generated separately for each pair of magnetic wires, and the maximum value thereof is as shown in FIG.
It becomes the same as the value when using one magnetic thin wire of 2
The effect of using a pair of magnetic thin wires as a pair cannot be obtained.

Therefore, in order to avoid magnetic mutual interference, FIG. 4 shows the structure of the magnetic marker 11a in which the magnetic fine wires to be arranged are arranged with a large interval. The coercive force of the magnetic wires in FIG. 4 is classified into the magnetic wires 2a ₃ and 2a.
₄ , magnetic wires 2b ₃ and 2b ₄ , magnetic wires 2c ₃ and 2c ₄
The magnetic fine wires are arranged in the order of 2a ₃ -2b ₃ -2c ₃ -2a ₄ -2b ₄ -2c _{4 and} the intervals between adjacent 6 magnetic fine wires are expanded. By doing so, mutual magnetic interference is small, and a set of 2
If the difference in coercive force between the two magnetic thin wires is very small, the induced voltage value obtained by using each magnetic thin wire will be twice as large as the induced voltage value obtained in FIG. can do.

Next, even in the case of using the magnetic marker 11a shown in FIG. 4, a countermeasure for the case where the induced voltages are generated separately as shown in FIG. 3 will be described. Even if magnetic thin wires are taken from the same wire, the coercive force changes depending on their length. FIG. 5 is a diagram showing the relationship between the length of the magnetic thin wire and the coercive force. As the length of the magnetic thin wire increases as shown in FIG. 5, the coercive force also increases.
The coercive force of the magnetic wire can be adjusted by changing its length. FIG. 6 is a schematic view of the magnetic marker 11b configured by changing the length of the magnetic thin wire. In FIG.
Magnetic thin wire 2a ₅ and 2a ₆ are those collected from the same wire, the same in length, the coercive force is towards the magnetic wire 2a ₆ is slightly smaller than the magnetic thin wire 2a _5, the magnetic wire 2a ₅ the magnetic wire 2a ₆ The coercive force of both is made the same by making it slightly shorter. This relationship is the same for the magnetic wires 2b ₅ and 2b ₆ and the magnetic wires 2c ₅ and 2c ₆ . The arrangement of these magnetic fine wires is 2a _5- , as in the case of FIG.
2b ₅ -2c ₅ -2a ₆ -2b ₆ -2c ₆ are arranged in this order with a large interval. Here, an example in which the coercive force of the magnetic thin wire is adjusted by the length of all three sets has been described.
Alternatively, it may be sufficient to adjust the coercive force of the two magnetic thin wires. By using the magnetic marker 11b shown in FIG. 6, a large induced voltage similar to that in FIG. 2 can be generated without the induced voltage being generated separately.

Finally, another method for adjusting the coercive force of the magnetic wire will be described. It is not to make the magnetic fine wires parallel to the magnetic field direction but to arrange them at an angle. FIG. 7 is a schematic view showing a state in which the magnetic wire has an angle θ with the magnetic field direction. By doing so, the effective magnetic field applied to the magnetic wire can be expressed by the equation (1).

H _eff = H _ex cos θ (1) where H _eff : effective magnetic field applied to the magnetic wire H _ex : magnetic field applied from the outside Therefore, by changing the angle θ, the effective magnetic field, that is, the time when the voltage is induced is adjusted. It is possible.

FIG. 8 shows a magnetic marker 11 in which one of a pair of two magnetic fine wires is angled with respect to the magnetic field direction.
It is a schematic diagram of c . In FIG. 8, magnetic fine wires (2a ₇ , 2
a ₈ ), magnetic thin wires (2b ₇ , 2b ₈ ), magnetic thin wires (2c
₇ and 2c ₈ ) are paired, but the magnetic wire 2
towards the magnetic thin wire 2a ₈ than a ₇ is a case coercive force is large, the direction of magnetic wire 2a ₈ disposed at an angle that satisfies respect to the magnetic field direction (1), the magnetic wire 2a ₇
And the time of the induced voltage generated in the magnetic wire 2a ₈ are the same. Similarly, regarding the magnetic thin wires 2b ₇ and 2b ₈ and the magnetic thin wires 2c ₇ and 2c ₈ , angles are given to the magnetic thin wires 2b ₈ and 2c ₈ , respectively. Thus, a large induced voltage similar to that in FIG. 2 can be generated without the induced voltage being generated separately. However, in this case as well, the coercive force can be adjusted with one set of magnetic thin wires or two depending on the situation.
You may finish with only a pair.

[0019]

EFFECTS OF THE INVENTION Conventionally, when an article is identified using a magnetic marker, if the article to be identified is small, or the area to which the magnetic marker is attached is small even if the article has a large shape, the magnetic fine wire of the magnetic marker is used. Since it had to be shortened, the induced voltage taken out from the detection coil was low, and the article identification was not performed sufficiently. On the other hand, the magnetic marker of the present invention makes good use of the material properties of the magnetic fine wire as described in the embodiments, and is configured by using a plurality of sets of magnetic fine wires, and a plurality of sets of magnetic fine wires are used. Even when the length is restricted, the induced voltage can be significantly increased compared to the conventional magnetic marker in which magnetic wires are arranged one by one according to the material characteristics, and the range of mounting small articles or magnetic markers is narrow. Highly accurate identification is possible for articles.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a magnetic marker of the present invention.

FIG. 2 is a waveform diagram of an induced voltage when a magnetic marker of the present invention is excited.

FIG. 3 is a waveform diagram of induced voltage when magnetic mutual interference occurs in a magnetic marker.

FIG. 4 is a schematic diagram showing the configuration of the magnetic marker of the present invention in which the intervals between magnetic thin wires are increased.

FIG. 5 is a diagram showing the relationship between the length of the magnetic thin wire and the coercive force.

FIG. 6 is a schematic diagram showing the configuration of the magnetic marker of the present invention in which the length of the magnetic thin wire is changed.

FIG. 7 is a schematic diagram showing a state in which a magnetic thin wire has an angle with a magnetic field direction.

FIG. 8 is a schematic diagram showing the configuration of a magnetic marker of the present invention, one of two magnetic fine wires forming a set having an angle with respect to the magnetic field direction.

FIG. 9 is a schematic diagram showing a main configuration of an article identification device using a magnetic marker.

FIG. 10 is a magnetic hysteresis curve diagram of a magnetic wire.

FIG. 11 is a waveform diagram of induced voltage when magnetic wires having different coercive forces are excited by a triangular wave AC magnetic field.

[Explanation of symbols]

1 magnetic marker 2 magnetic nanowire 2a magnetic wire 2a ₁ magnetic wire 2a ₂ magnetic wire 2a ₃ magnetic nanowire 2a ₄ magnetic wire 2a ₅ magnetic wire 2a ₆ magnetic wire 2a ₇ magnetic wire 2a ₈ magnetic wire 2b magnetic wire 2b ₁ magnetic wire 2b ₂ magnetic wire 2b ₃ magnetic nanowire 2b ₄ magnetic wire 2b ₅ magnetic wire 2b ₆ magnetic wire 2b ₇ magnetic wire 2b ₈ magnetic wire 2c magnetic wire 2c ₁ magnetic wire 2c ₂ magnetic wire 2c ₃ magnetic nanowire 2c ₄ magnetic wire 2c ₅ magnetic wire 2c ₆ Magnetic thin wire 2c ₇ Magnetic thin wire 2c ₈ Magnetic thin wire 3 Article 4 Pulley 5 Belt 6 Excitation coil 7 AC power supply 8 Detection coil 9 Measuring instrument 10 Personal computer 11 Magnetic marker 11a Magnetic marker 11b Magnetic marker 11c Magnetic marker

Claims (6)

[Claims] 1. A magnetic marker for identifying an article for detecting a change in magnetic flux of each magnetic thin wire by AC-exciting a plurality of magnetic thin wires each having a square magnetic hysteresis curve, the magnetic markers having the same coercive force. A magnetic marker for article identification, comprising a set of thin wires, and a plurality of pairs of magnetic wires having different coercive forces from each other are arranged in parallel in parallel to the direction of the applied magnetic field. 2. The magnetic marker for identifying articles according to claim 1, wherein the plurality of magnetic fine wires belonging to each set are arranged with a space between which a change in magnetic flux can be detected. 3. A magnetic marker for detecting a change in magnetic flux of each magnetic thin wire by AC-exciting a plurality of magnetic thin wires each having a square magnetic hysteresis curve, wherein a plurality of magnetic thin wires having slightly different coercive forces are used. One set consists of multiple sets of magnetic fine wires whose coercive forces differ greatly from each other in parallel parallel to the direction of the applied magnetic field. A magnetic marker for identifying articles, characterized by adjusting the coercive force of a thin wire. 4. The magnetic marker according to claim 3, wherein one of the plurality of magnetic fine wires belonging to each set has a smaller coercive force and is shortened. 5. A magnetic marker for detecting a change in magnetic flux of each magnetic thin wire by AC-exciting a plurality of magnetic thin wires each having a square magnetic hysteresis curve, wherein a plurality of magnetic thin wires having slightly different coercive forces are detected. One set, a plurality of sets in which the coercive force of the magnetic fine wires greatly differ from each other are arranged in parallel, and some of the plurality of magnetic fine wires belonging to each set have an angle with respect to the direction of the applied magnetic field. A magnetic marker for identifying an article, characterized in that the coercive force of a magnetic thin wire is adjusted by. 6. The magnetic marker for identifying articles according to claim 5, wherein one of the plurality of magnetic fine wires belonging to each set has a smaller coercive force and has an angle with the magnetic field direction.