JPH05250506A - Reading and discriminating device for magnetic marker - Google Patents

Abstract

PURPOSE:To obtain a uniform and wide-range AC magnetic field area due to an exciting coil part by reducing the variation of the pulse voltage value of a detecting coil part. CONSTITUTION:The detecting coil part which has plural detecting coils 9a wound around the spool of a hollow supporting body whose inside diameter is larger than the shape of an article, is used and a magnetic marker is allowed to pass the inside part of the hollow supporting body. The exciting coil part which has at least three exciting coils 13a which are formed in the outer peripheral part of the enclosure to have the same axis is used. These detecting coil part and exciting coil part are combined and provided to obtain an approximately fixed pulse voltage value independently of the passage position of the magnetic marker 1, and a uniform AC magnetic field zone is considerably extended. Since both of them are used, respective advantages are involved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic marker reading / identifying device attached to an article in order to identify the type, quantity, etc. of the article.

[0002]

2. Description of the Related Art The construction of a magnetic marker reading and identifying apparatus for reading information such as the type and quantity of an article from a magnetic marker attached to the article, and a detection coil used in this apparatus are disclosed by the same applicant. JP-A-2-290589, JP-A-3-41387, and Japanese Patent Application No. 2-3183.
No. 03, etc.

FIG. 4 is a schematic diagram for explaining the configuration and operation of the magnetic marker reading / identifying apparatus. In FIG. 4, a magnetic marker 1 composed of a plurality of amorphous magnetic thin wires or ribbons having rectangular magnetic hysteresis characteristics or magnetic flux jump characteristics having different coercive forces.
The article 2 attached with is mounted on a belt 4 stretched over two pulleys (not shown), and moves in the direction of the arrow as the belt 4 runs due to the rotation of the pulleys. Two exciting coils 5 for generating an alternating magnetic field are installed at a predetermined position in a section where the article 2 is conveyed by the belt 4 so as to be connected to an alternating current oscillator 6, and the magnetization reversal of the magnetic marker 1 caused by the alternating magnetic field is accompanied. the detection coil only 7a for detecting a power sale magnetic flux change as induced electromotive voltage detection coil unit 7 connected to the plurality of series, is connected to the instrument 8 below the belt 4. In FIG. 4, the article 2 to which the magnetic marker 1 is attached passes through the central portion of the exciting coil 5, but the two exciting coils 5 may be arranged so as to face each other on the side surface of the belt 4.

In the magnetic marker reading / identifying apparatus as described above, the pulse voltage train from the detection coil unit 7a is read a plurality of times, and the measuring instrument 8 performs averaging. The voltage from the detection coil unit 7a includes noise such as disturbance noise and white noise in addition to the induced electromotive voltage generated by the magnetization reversal of the magnetic marker 1. Therefore, the induced electromotive voltage and the noise can be detected only once. Sometimes it is difficult to distinguish Noise having no periodicity with respect to time can be subjected to arithmetic averaging to reduce the noise voltage and increase the S / N ratio. Further, the pulse voltage train generated in the detection coil unit 7a is generated twice in the 1/4 cycle and the 3/4 cycle during one cycle of the AC magnetic field. When the timing at which the AC magnetic field becomes 0 is the origin of the pulse generation time, the pulse generation times are different due to the influence of geomagnetism. When such a pulse voltage train is added and averaged, a pulse voltage train having a number equal to or larger than the true number of pulses is generated, which causes an error in reading identification. Therefore, in this device, sampling is performed only at any one time.

[0005]

However, the magnetic marker reading / identifying apparatus having the above-described structure has the following problems. As mentioned above, the article 2 with the magnetic marker 1
Is identified by a magnetic marker 1 consisting of an amorphous magnetic thin wire or ribbon.
It is to detect the magnetic flux change accompanying the magnetization reversal as the induced electromotive force. As a characteristic of the amorphous magnetic thin wire, the magnetic poles are polarized in the axial direction, and the magnetic flux density distribution formed in the surrounding space by the amorphous magnetic thin wire is the center of the amorphous magnetic thin wire, such as a bar magnet. It has a cylindrical spread on the shaft. Further, the magnitude of the magnetic flux density at a certain space point is attenuated in proportion to the square of the distance to the space point about the amorphous magnetic thin wire. Therefore, in the device configuration as shown in FIG. 4, even if the distance between the detection coil unit 7 and the magnetic marker 1 is slightly different, the magnitude of the magnetic flux density and the magnetic flux amount interlinking with the detection coil unit 7 are different from each other. Since it is attenuated in proportion to the square of, the way of placing the article 2 on the belt 4 needs to be set so that the distance between the article 2 and the detection coil unit 7 is not too large.

The alternating magnetic field applied to the magnetic marker 1 must be uniform at least within the range where the detection coil section 7 is located in the region where the magnetic marker 1 passes. Since conversion of pulse voltage to bit signal occurs at different times for each pulse voltage, multiple windows are set on the time axis and the presence / absence of pulse voltage in the window is checked.
Since the bit is obtained as the value signal, if the AC magnetic field strength in the region where the magnetic marker 1 passes is non-uniform, the time at which the pulse voltage is generated fluctuates, and the outside of the set window or another window is generated. In some cases, a pulse voltage may be generated inside, and the obtained signal is different from the original bit signal.

Further, as described above, in order to raise the S / N ratio of the signals, a plurality of signals are added and averaged to reduce the noise level. However, when pulse signals having different generation times are added and averaged, The pulse voltage value becomes a value that is considerably lowered due to the instantaneous value, and the phenomenon that the signal level is not reached also occurs. On the other hand, in order to obtain a uniform magnetic field, there is a method of using a Helmholtz coil or a solenoid coil as the exciting coil 5. The device of FIG. 4 utilizes a Helmholtz coil. In the Helmholtz coil, two circular coils having the same radius have the same central axis, and the coil spacing has the same dimension as the coil radius. In this way, the magnetic field is nearly uniform near the center of the central axis of the coil. Similarly, in the case of a solenoid coil, the magnetic field is almost uniform on the central axis. However, since the solenoid coil requires continuous winding of copper wire in a cylindrical shape, winding work becomes difficult when the device is large, while the Helmholtz coil has a uniform magnetic field range between coils on the central axis. It has a drawback that it is only near the center and is limited to a very narrow range.

The present invention has been made in view of the above points, and an object thereof is to provide a detection coil section for reducing fluctuations in pulse voltage value, and an excitation coil section for obtaining a uniform AC magnetic field region in a wide range. Another object of the present invention is to provide a reading / identifying device for a magnetic marker having the following.

[0009]

In order to solve the above-mentioned problems, a magnetic marker reading / identifying apparatus of the present invention comprises a plurality of hollow markers provided on the outer circumference of a hollow support having an inner diameter larger than the shape of the article. A detection coil unit having a detection coil is used, and a magnetic marker is passed through the inner diameter portion of the hollow support, or at least three excitation coils are formed on the outer peripheral portion of the housing so as to share the central axis. The excitation coil unit is used, and the detection coil unit and the excitation coil unit are combined and provided.

[0010]

The magnetic marker reading / identifying device of the present invention is configured as described above, and thus the detecting coil section is
Since the article to be identified is passed through the inner diameter portion of the detection coil portion, the magnetic flux generated from the magnetic marker can be most efficiently interlinked with the detection coil, and a larger pulse voltage can be obtained than in the past. Further, when the inner diameter of the detection coil is increased, the amount of magnetic flux interlinking the detection coil portion is attenuated in proportion to the first power of the inner diameter, so that the reduction rate of the pulse voltage value becomes smaller than that in the conventional case. Furthermore, when the article passes through the inner diameter portion of the detection coil portion, a substantially constant pulse voltage value can be obtained regardless of the passage position of the magnetic marker.

With respect to the exciting coil portion, it is possible to greatly expand the uniform alternating magnetic field band. The shape of each exciting coil is not limited to a circular shape as a Helmholtz coil, but may be a rectangular shape, and the exciting coil portion can be easily manufactured without forming a winding portion in the entire region unlike a solenoid coil. Furthermore, by using the above-described detection coil unit and excitation coil unit in combination, the respective advantages are synergized, and a large pulse voltage value is obtained from a magnetic marker that passes through a uniform AC magnetic field band, and highly accurate detection is performed. be able to.

[0012]

EXAMPLES The present invention will be described below based on examples. Since the magnetic marker reading / identifying apparatus of the present invention is basically the same as that shown in FIG. 4, the illustration and description of the entire apparatus are omitted at first, and first, the detection coil unit used in the apparatus of the present invention, Similarly, the exciting coil portion used in the device of the present invention will be described, and finally, a device combining these will be described.

FIG. 1 is a schematic cross-sectional view showing the structure of a detection coil unit 9 used in the magnetic marker reading / identifying apparatus of the present invention. In FIG. 1, the detection coil unit 9 includes a plurality of individual detection coils 9a each having a winding 11 wound around a plurality of protrusions provided on the outer periphery of a winding frame 10 which is a hollow structural support. It is an individually formed air-core coil, and has a structure in which an article to be identified is passed through its inner diameter portion. Therefore, the size of the inner diameter D of the detection coil unit 9 must be equal to or larger than the size of the passing article. Further detection coil section
9 , the distance L between the detection coils 9a is set to be equal to or less than the length of the magnetic thin wire, and the detection coils 9a are electrically connected in series.

In this way, the magnetic flux amount generated from the magnetic marker 1 can be most efficiently interlinked with each detection coil 9a, and conventionally only a part of the magnetic flux amount from the magnetic marker 1 can be used. Whereas not possible, the amount of magnetic flux that can be detected by the magnetic marker 1 increases, so that the obtained pulse voltage value also becomes larger than in the prior art. Next, FIG. 2 shows an exciting coil unit 12 used in the reading and identifying apparatus of the magnetic marker of the present invention.
It is a schematic cross-sectional view showing the configuration of. In FIG. 2, the exciting coil unit 12 has at least three exciting coils 13a fitted in a housing 13 made of a non-magnetic material, and the central axes of these are accurately matched, and the intervals between the exciting coils 13a are the same. I am doing it. In FIG. 2, three exciting coils 13a are shown.
Is shown, and these are electrically connected in series. Here, the three exciting coils 13a are used because in order to obtain a uniform alternating magnetic field band, each exciting coil 1
This is because three or more 3a are required. Also, the housing 1
By also using 3 as a mounting structure for the detection coil unit 9 (not shown), it is possible to form an integrated structure as a pulse voltage detection unit.

FIG. 3 is a schematic diagram showing a magnetic marker reading / identifying apparatus using a combination of the detecting coil unit 9 shown in FIG. 1 and the exciting coil unit 12 shown in FIG. The same reference numerals are used for. However, in FIG. 3, for convenience, the winding frame 10 of the detection coil unit 9 and the casing 13 of the excitation coil unit 12 are not shown, and the method for identifying the article 2 of this device is described in FIG. Since it is the same in principle as the above, the description thereof will be omitted. The apparatus of Figure 3, the axial direction of the magnetic marker 1 or the amorphous magnetic wire, as in the case of FIG. 4 is the same as the conveying direction of the article 2 by the belt 4, the inner diameter of the detection coil unit 9 4 is different from that shown in FIG. 4 in that the belt 4 that conveys the article 2 is passed through. There are four ways of placing the article 2 on the belt 4 with reference to the surface on which the magnetic marker 1 is attached to the article 2, but since the magnetic marker 1 passes through the inner diameter portion of the detection coil unit 9 , the article 2 is placed on the belt 4. It is possible to obtain a substantially constant pulse voltage regardless of the passing position of. Further, this magnetic marker reading / identifying device is installed vertically or diagonally between the belt conveying systems, and a step is formed between the entrance and the exit of the detection coil unit 9 through which the belt 4 passes, thereby detecting the detection coil unit. Even if the article 2 is dropped inside the article 9 or the inner wall surface of the detection coil unit 9 is slid, that is, the conveying speed is increased, the article 2 can be identified.

[0016]

As described above, the magnetic marker reading / identifying apparatus of the present invention has the following advantages as described in the embodiments. By passing the magnetic marker through the inner diameter of the detection coil part in which a plurality of detection coils are formed on the winding frame that is a hollow support, a substantially constant pulse voltage value can be obtained regardless of the position where the magnetic marker passes. As a result, the restrictions on how to place an article with a magnetic marker on the belt are remarkably relaxed, and the intervals between the detection coils are set to the length of the magnetic marker or less and the detection coils are electrically connected in series. By connecting, it is possible to detect a signal having the same pulse voltage value a plurality of times within a time period in which the article passes through the detection coil section, and the average of these signals is added to the S / S signal without affecting the pulse voltage value. The N ratio can be increased.

Since the central axes of the respective exciting coils are accurately aligned with each other by using the exciting coil portion in which at least three exciting coils are arranged in the housing, the AC magnetic field strength is uniform over a wide spatial range. Since it is possible to form a region having a pulse width, it is possible to always obtain a pulse signal having a constant pulse generation time regardless of the passage position of the magnetic marker in this region.

By using the magnetic marker reading / identifying device based on the combination of the above, the respective effects are synergized, and a pulse voltage value with little fluctuation is detected with high accuracy from a magnetic marker that passes a uniform AC magnetic field over a wide range. It is possible to

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of a detection coil unit used in the device of the present invention.

FIG. 2 is a schematic cross-sectional view showing the structure of an exciting coil unit used in the device of the present invention.

FIG. 3 is a schematic diagram showing an apparatus of the present invention in which the detection coil unit of FIG. 1 and the excitation coil unit of FIG. 2 are combined.

FIG. 4 is a schematic diagram for explaining the configuration and operation of a magnetic marker reading / identifying device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic marker 2 Article 4 Belt 5 Excitation coil 6 AC oscillator 7 Detection coil part 7a Detection coil single unit 8 Measuring instrument 9 Detection coil part 9a Detection coil 10 Winding frame 11 Winding 12 Excitation coil part 13 Housing 13a Excitation coil

Claims (4)

[Claims] 1. An article in which a plurality of magnetic fine wires or thin strips are used as magnetic markers and which are attached in parallel in the longitudinal direction is placed on a belt to pass an AC magnetic field band generated from an exciting coil during traveling, and A reading / identifying device of a magnetic marker for extracting a pulse voltage generated by a change in magnetic flux by a detection coil provided in an AC magnetic field band, wherein a plurality of detection coils provided on the outer circumference of a winding frame of a hollow support having an inner diameter larger than the shape of the article. And a detection coil unit for allowing a magnetic marker to pass through the inner diameter of the hollow support. 2. The magnetic marker reading / identifying device according to claim 1, wherein the intervals between the respective detection coils of the detection coil section are equal to or less than the length of the magnetic thin wire or the ribbon, and the respective detection coils are electrically connected. A magnetic marker reading / identifying device characterized by being connected in series. 3. The magnetic marker reading / identifying apparatus according to claim 1, further comprising an exciting coil portion formed on an outer peripheral portion of the casing, wherein at least three exciting coils sharing a central axis with the casing are formed. Read and identify device for magnetic markers. 4. A magnetic marker reading / identifying apparatus comprising: the detection coil section according to claim 1 or 2; and the excitation coil section according to claim 3.