JPH05250530A - Method for determining dimensions of magnetic narrow wire for magnetic marker - Google Patents

Abstract

PURPOSE:To maintain a large induced voltage generated in a detecting coil even at the time of using short magnetic narrow wires by determining the wire diameter in accordance with the allowable length of magnetic narrow wires. CONSTITUTION:A diagram of relations between respective allowable lengths of plural magnetic narrow wires different by diameter used for a magnetic marker and the induced voltage generated by AC exciting of the magnetic marker is obtained, and a diagram of relations between allowable lengths and wire diameters with an optimum induced voltage value as the parameter is obtained. The wire diameter for the allowable length is determined in accordance with this diagram, and thereby, the optimum wire diameter is determined in accordance with the allowable length of magnetic narrow wires, and material characteristics of magnetic narrow wires are effectively used to minimize the reduction of the induced voltage generated in the detecting coil regardless of the use of short magnetic narrow wires, and high-precision detection is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a wire diameter with respect to an allowable length of a magnetic wire attached to an article and used as a magnetic marker for identifying the kind and quantity of the article.

[0002]

2. Description of the Related Art A method is known in which an article having a magnetic marker is passed through an alternating magnetic field, and an induced voltage due to a magnetic flux generated in the magnetic marker is detected by a coil to identify the type of the article. FIG. 7 is a schematic view showing the configuration of the main part of an example of an article identification device using a magnetic marker.
In FIG. 7, the article 2 with the magnetic marker 1 attached is on the belt 4 stretched over the two pulleys 3, and the article 2 together with the magnetic marker 1 is on the belt 4 traveling by the rotation of the pulley 3 in the direction of the arrow. Moving. While the vehicle is running on the belt 4, two exciting coils 5 are arranged so as to sandwich the belt 4 from both sides.
It is connected to the. A plurality of detection coils 7 provided near the belt 4 sandwiched between the two exciting coils 5 are connected to a measuring instrument 8. The magnetic flux of the magnetic marker 1 traveling on the belt 4 together with the article 2 is changed by the alternating magnetic field generated from the exciting coil 5. The change in magnetic flux is detected by the coil 7
It is taken out as an induced voltage generated in 1 and processed by the measuring device 8 to identify the article 2.

Next, the magnetic marker 1 will be described. In the magnetic marker 1, a plurality of magnetic fine wires having different coercive forces are fixed in parallel on, for example, a plastic plate. As the material of the magnetic marker 1, it is suitable to use a thin wire of, for example, an amorphous magnetic alloy having a large Barkhausen effect with a magnetic hysteresis curve having a square shape. The number of magnetic fine wires to be used varies depending on the type of the identification article, but here, the case where five magnetic fine wires are used will be described. The magnetic hysteresis curve of each magnetic wire is shown in FIG. The horizontal axis of FIG. 8 represents a magnetic field, and each symbol H represents coercive force. As shown in FIG. 8, the magnetic marker 1 uses the same five magnetic fine lines a _{1 to} a ₅ whose coercive force is different at almost equal intervals in order to make the time intervals of induced voltages to be described later the same. In FIG. 8, each magnetic thin wire has the same sign on the + side and the-side,
The magnetic hysteresis curve of the same material is shown. When these are excited by an alternating current with the magnetic field waveform shown in FIG. 9, a time t ₁ corresponding to the coercive force H _{1 to} H ₅ of each magnetic thin wire a _{1 to} a ₅
The magnetic flux abruptly reverses at ~ t5, and _five pulsed voltages are induced in the detection coil 7. This induced voltage can be processed by the measuring instrument 8 to identify the article 2.

[0004]

As described above, the magnetic marker 1 for identifying an article using the amorphous magnetic alloy thin wire is useful, but has the following problems to be solved. When the article 2 is identified using the magnetic marker 1, even if the article 2 is located at a position distant from the detection coil 7 to some extent, the range of application of the size of the article 2 can be expanded if the article 2 can be accurately detected. You can For that purpose, the induced voltage generated from the magnetic wire used for the magnetic marker 1 must be increased. This induced voltage increases as the diameter of the magnetic thin wire used increases and the length increases.

On the other hand, since the magnetic marker 1 is attached to the article 2 to be identified, its length is naturally limited by the shape and size of the article 2. Therefore, when the attachment range of the magnetic marker 1 to the article 2 is small, that is, when the magnetic thin wire has to be shortened, the induced voltage generated from the magnetic marker 1 becomes small and the detection accuracy deteriorates. From this, it is desirable that the magnetic marker 1 can be detected with high accuracy regardless of the length of the magnetic thin wire.

The present invention has been made in view of the above points, and an object of the present invention is to appropriately select a wire diameter capable of accurately identifying an article according to an allowable length of a magnetic thin wire for a magnetic marker. It is to provide a method to determine.

[0007]

In order to solve the above problems, the method of the present invention is to determine the diameter of a magnetic thin wire according to the allowable length of the magnetic thin wire. Relationship between the allowable lengths of magnetic wires with different diameters and the induced voltage generated by AC excitation of the magnetic marker, and then the relationship between the allowable length and the wire diameter with the optimum induced voltage value as a parameter. A line diagram is obtained, and the line diameter for the allowable length is determined from this line diagram.

[0008]

The induced voltage generated in the detection coil due to the change in the magnetic flux of the magnetic thin wire becomes smaller as the length of the magnetic thin wire becomes shorter, but the aspect depends on the wire diameter of the magnetic thin wire. As described above, the method of the present invention can effectively utilize the material characteristics of the magnetic thin wire by determining the optimum diameter of the magnetic thin wire according to the allowable length of the magnetic thin wire. , The reduction of the induced voltage generated in the detection coil can be suppressed to the minimum, and highly accurate detection can be performed.

[0009]

EXAMPLES The method of the present invention will be described below based on examples. FIG. 1 is a diagram showing the relationship between the length and the induced voltage for each diameter of a magnetic thin wire. Here, as a typical diameter of the magnetic thin wire, 30 μm is a dotted line, 50 μm is a solid line,
100 μm is represented by a chain line. From FIG. 1, the induced voltage becomes larger as the wire diameter becomes thicker when the magnetic thin wire is longer, but the induced voltage becomes smaller when the magnetic thin wire becomes shorter, and the degree of change varies depending on the wire diameter. It can be seen that the smaller the diameter, the larger the diameter.

However, in reality, the wire diameters are 40 μm and 60 μm.
For magnetic thin wires with other wire diameters, etc., the same diagram as in Fig. 1 was obtained by a separate experiment, and if all of these were plotted on the diagram, the diagram would be complicated and difficult to understand.
As mentioned above, in FIG.
Although only m, 50 μm, and 100 μm are lifted, FIG. 2 is a diagram showing the relationship between the length and the length of the induced voltage due to the change in the magnetic flux of each magnetic fine wire, which is the maximum, and the wire diameter. That is, FIG. 2 shows the optimum wire diameter for the length of each magnetic thin wire.

5 coercive force different from each other, wire diameter 5
FIG. 3 shows a waveform diagram of an induced voltage generated in the detection coil 7 when the magnetic marker 1 is constructed by using a magnetic wire of 0 μm and a length of 50 mm. Similarly, FIG. 4 is an induced voltage waveform diagram when the magnetic thin wire has a diameter of 30 μm and a length of 50 mm, and FIG. 5 is an induced voltage waveform diagram when the magnetic thin wire has a diameter of 50 μm and a length of 25 mm. Is the diameter of the magnetic thin wire 30μ
The induced voltage waveform figure when m and length are 25 mm is shown.

Here, the length 50 of the magnetic wire shown in FIGS.
When the wire diameter is 50 μm, the induced voltage value is about 20% higher than the wire diameter of 30 μm. Similarly, comparing the magnetic fine wires with a length of 25 mm shown in FIGS. 5 and 6, contrary to the case of the magnetic fine wires with a length of 50 mm, the wire diameter of 30 μm is 50 μm.
It can be seen that the induced voltage value is about 70% larger than that of No. 1, and it is advantageous to properly use the wire diameter depending on the allowable length of the magnetic thin wire.

This will be described with reference to the diagram of FIG. 1 again. When determining the magnetic fine wire constituting the magnetic marker 1, the length of the magnetic fine wire corresponding to the intersection of the curves of FIG. 1 is determined. , If the actual allowable length is equal to this, any wire diameter may be used, and if the allowable length is greater than the length of the magnetic thin wire corresponding to the intersection, the one with the larger wire diameter is selected. When the allowable length is smaller than the length of the magnetic thin wire corresponding to the intersection, the smaller wire diameter is used. This may be determined from the relationship diagram of length and wire diameter in FIG. For example, when using a magnetic fine wire with an allowable length of 30 mm or more,
When the wire diameter is 35 μm or more and the allowable length is 20 to 30 mm, the wire diameter is 28 to 35 μm, and when the allowable length is 20 mm or less, the wire diameter is 28 μm or less.

[0014]

With respect to the magnetic fine wire constituting the magnetic marker used for identifying the article, the relationship between the induced voltage generated from the detection coil due to the change in the magnetic flux of the magnetic fine wire and the length and diameter of the magnetic fine wire itself has hitherto been known. It is not clear that the magnetic wire having the same wire diameter has always been used for the allowable length, but the method of the present invention can determine and select the optimum wire diameter according to the allowable length. Therefore, by effectively utilizing the material properties of the magnetic thin wire, when the magnetic wire having a short allowable length is used, the article to be identified is separated from the detection coil to some extent without lowering the induced voltage generated in the detection coil. Even at the position, it is possible to maintain the detection accuracy of the article identification sufficiently high.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the length of a magnetic thin wire and the induced voltage for each wire diameter.

FIG. 2 is a diagram showing the relationship between the length of the magnetic thin wire and the optimum wire diameter.

FIG. 3 is a waveform diagram of an induced voltage for a magnetic wire having a wire diameter of 50 μm and a length of 50 mm.

FIG. 4 is a waveform diagram of induced voltage for a magnetic wire having a wire diameter of 30 μm and a length of 50 mm.

FIG. 5 is a waveform diagram of an induced voltage for a magnetic wire having a wire diameter of 50 μm and a length of 25 mm.

FIG. 6 is a waveform diagram of an induced voltage for a magnetic wire having a wire diameter of 30 μm and a length of 25 mm.

FIG. 7 is a schematic diagram showing a main part configuration of an article identification device using a magnetic marker.

FIG. 8: Magnetic hysteresis curve diagram of magnetic wire

FIG. 9 is a magnetic field waveform diagram for alternating-current excitation of a magnetic marker.

[Explanation of symbols]

 1 Magnetic Marker 2 Article 3 Pulley 4 Belt 5 Excitation Coil 6 AC Power Supply 7 Detection Coil 8 Measuring Instrument

Claims (2)

[Claims] 1. A detection coil which is provided with a magnetic marker in which a plurality of magnetic thin wires having a high magnetic permeability and a rectangular magnetic hysteresis curve and having different coercive forces and which are different in coercive force are arranged in parallel in the longitudinal direction and which is excited by an alternating current to detect a coil. In determining the dimension of the magnetic fine wire for the magnetic marker for identifying the article by the induced voltage generated in the, the wire diameter is determined according to the allowable length of the magnetic fine wire restricted by the shape of the article. A method for determining the dimension of a magnetic thin wire for a characteristic magnetic marker. 2. The method according to claim 1, wherein first, a relationship diagram between the allowable lengths of a plurality of magnetic fine wires having different diameters and the induced voltage is obtained, and then the optimum induced voltage value is used as a parameter. A method for determining a dimension of a magnetic fine wire for a magnetic marker, comprising: obtaining a relational diagram between an allowable length and the wire diameter, and determining the wire diameter with respect to the allowable length from the diagram.