JPH04112281A - Signal processing method for article discriminating device - Google Patents

Abstract

PURPOSE:To certainly operate the discrimination of articles in a fixed time by allowing plural pulse voltage column signals from plural detecting coils to pass a comparator, selecting the detecting coils in which the pulse voltage column signals capable of being discriminated are generated, and operating the arithmetic, processing of the signals from the detecting coil. CONSTITUTION:When an article 2 to which a magnetic marker 1 is adhered, that is, an object to be detected passes between magnetic coils 5a and 5b while being put on a belt 4, a magnetic marker 1 is magnetized by AC magnetic field generated there, and the magnetic fluxes are reversed. Then, the kind of the magnetic marker 1, that is, the article 2 is discriminated by selecting a signal which is optimal for the detection of the magnetic marker 1, among pulse voltage columns generated detecting coils 7a-7c in accordance with the change of the magnetic fluxes at that time, and comparing the pulse voltage columns with reference pulse voltage columns in order to recognize a pattern. Thus, the discrimination of the article 2 is efficiently and accurately operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal processing method for a magnetic marker attached to an article and used for identifying the type of article or counting the quantity of the article.

[Conventional technology]

It is known that attaching a marker to an article, using a magnetic material as the marker, and applying an alternating magnetic field to the marker is used to prevent the article from being stolen.For example, the magnetic material has a square magnetic history characteristic. When an article to which an amorphous magnetic thin wire or ribbon marker is attached passes through an alternating current magnetic field, the change in magnetic flux caused by the magnetization of the marker being reversed by the alternating magnetic field can be extracted from the detection coil.

Amorphous magnetic materials have unprecedented soft magnetic properties, making it possible to obtain small and lightweight markers with high sensitivity. By arranging the bands in combination, the magnitude of the magnetic field differs when the magnetization is reversed in an alternating current magnetic field, so this can be detected as a time-series pulse voltage and the type of magnetic marker, that is, the article, can be identified. It is possible.

[Problem to be solved by the invention]

The detection coil used in the above article identification device is
Since detection sensitivity is insufficient with just one coil, multiple detection coils are arranged in the AC magnetic field band to obtain a constant detection sensitivity regardless of the passing position of the article. To identify markers, when processing signals from detection coils, especially when a plurality of detection coils are used, the signal processing must be performed efficiently and accurately. An object of the present invention is to provide an effective signal processing method when a plurality of detection coils are used in an identification device.

[Means to solve the problem]

In the signal processing method of the present invention, a plurality of signals generated from a plurality of detection coils installed in an article identification device are passed through a comparator, and a pulse voltage exceeding a predetermined threshold is generated using the comparator. In order to make a 1.0 judgment on the presence or absence of a pulse voltage train depending on whether it occurs or not, and to reliably select the optimal detection coil for detection, the presence or absence of a pulse voltage train is judged by a comparator several times. A signal that is determined to have a pulse voltage train after several checks is passed through a selection circuit to select that detection coil, and the signal from the selected detection coil is passed through an arithmetic circuit to read the pulse voltage train pattern, and this arithmetic signal is Items are identified by passing them through a personal computer.

[Effect]

The time from generation to disappearance of the pulse voltage train generated in the detection coil depends on the shape of the detection coil, the speed at which the magnetic marker passes through the AC magnetic field band, the amount of magnetic flux generated by the magnetic marker,
The time during which a signal effective for identifying an object is generated from the detection coil is determined by the distance between the magnetic marker and the detection coil, etc., so the signal most suitable for detection is generated from among the multiple detection coils installed. The above-mentioned signal processing method of the present invention, in which the signal processing method of the present invention must be performed by selecting a detection coil to perform signal processing, takes these points into full consideration. After selecting a detection coil that generates an identifiable pulse voltage train signal through a comparator, the product can be identified within a specified time by processing the signal from the selected detection coil. It can be done reliably.

〔Example〕

The present invention will be explained below based on examples.

First, an outline of an article identification device to which the magnetic marker detection method according to the present invention is applied will be described. FIG. 1 is a schematic diagram showing the main part configuration of an example of the device. In FIG. 1, an article 2 to which a plurality of magnetic markers 1 are attached is placed on a belt 4 stretched between two pulleys 3, and the article 2 is carried along with the magnetic marker 1 on a belt 4 that travels by the rotation of each pulley 3. Move in the direction of the arrow above. Two excitation coils 5a that generate an alternating magnetic field so as to sandwich the belt 4 from both sides.
, 5b are arranged, and these are connected to an AC oscillator 6. A plurality of detection coils, for example 7a7b and 7c, are connected in series to the measuring device 8 and the personal computer 9, for detecting the change in magnetic flux accompanying the magnetization reversal of the magnetic marker 1 caused by the alternating magnetic field as an induced electromotive voltage. The detection coils 7a, 7b, and 7c are all twin coils in order to cancel the electromotive force induced by the alternating current magnetic field. Measuring instrument 8
The induced electromotive force pulse train generated in the detection coil 7 is subjected to signal processing, and the pattern can be recognized, for example, 1°0 depending on the presence or absence of a pulse voltage at a predetermined phase that is the reference of the alternating current magnetic field.
The personal computer 9 has a function of identifying the type of the magnetic marker 1.

With the above device configuration, the magnetic marker 1 as shown in FIG.
When the article 2, that is, the object to be detected, to which is pasted rides on the belt 4 and passes between the magnetic coils 5a and Sb, the magnetic marker 1 is magnetized by the alternating magnetic field generated there, and the magnetic flux is reversed. Detection coil 7 due to magnetic flux change
Among the pulse voltage trains generated at a, 7b, and 7c, the optimal signal for detecting the magnetic marker 1 is selected, and the pulse voltage train is compared and contrasted with the reference pulse voltage train to determine the difference of 1.0 from the presence or absence of the pulse voltage. By converting and recognizing patterns,
The magnetic marker 1, that is, the type of article 2 is identified.

Next, the structure of the magnetic marker used in the present invention and its identification method will be described. It is suitable to use, for example, an iron-based amorphous magnetic thin wire or thin ribbon having rectangular magnetic hysteresis characteristics as the M1 marker. Although a plurality of magnetic markers 1 can be used as they are, a case will be described in which a plurality of magnetic markers 1 are arranged and configured as one detection element. FIGS. 2(a) and 2(b) are partially peeled perspective views showing the detection element side. Figure 2(a) shows a magnetic marker using four amorphous magnetic thin wires 1-, 1b, 1c, and 1m, arranged in parallel in the longitudinal direction.
The second magnetic marker (2) is embedded in, for example, two thin plastic fixing plates 13.

On the other hand, in FIG. 2(b), the amorphous magnetic thin wire 1,
, 1 h.

A magnetic marker is constructed using the three wires 1 and 1, and is placed on the detection element side. That is, these detection elements l are shown in Fig. 2 (
In the case of b), the amorphous magnetic thin wire 1c is missing compared to Fig. 2(a). And these magnetic thin wires 111°15. lゎ、1. have different coercive forces Hc, and their magnetic characteristic diagrams are shown in Figure 3. As shown in Figure 3, the magnetic thin wires 1-, 1
The respective coercive forces H corresponding to b, 1 c, l m
c is in the relationship Hc-<Hcb<Hcc<HCd.

Figures 4 (a), (b), and (C) show the AC magnetic field waveforms and the detection coil 7a + 7b due to the AC magnetic field.
Figure 4(a) shows the AC magnetic field waveform, and Figure 4(a) shows the pulse voltage train induced in either +7c. ) are detection coils 7a, 7b, 7 when using magnetic marker ■
A pulse voltage train occurring in either of the pulse voltage trains is shown in FIG. 4 (C), and the horizontal axis represents time. Here, Figure 4 (
Figure 4 (a) shows the alternating current magnetic field waveform of a) in the case of a triangular wave.
) to (C), the predetermined phases of the triangular alternating current magnetic field Ha+ Hb, )(c,
It can be seen that a pulse voltage is generated at Ha. Hl represents the maximum value of the alternating magnetic field. If these pulse voltage trains are expressed by the measuring instrument 8 as 1.0 depending on the presence or absence of the pulse voltage, Table 1 shows.

Table 1 Next, a method for processing a plurality of input signals from a plurality of detection coils installed will be described. FIG. 5 shows the excitation coils 5a, 5b, and the like when a magnetic marker (or a detection element using the magnetic marker) 14.15.1.6 configured as, for example, a magnetic marker (2) or (u) passes over the belt 4. The alternating current magnetic field band 17 generated by the detection coils 7a and 7b
, 7c, and magnetic marker 14. Is.

16, and is shown in a schematic diagram as seen from above the belt 4. For example, as shown in FIG. 5, the magnetic marker 14 is on the left end of the belt 4.

When the magnetic marker 15 is placed at the center and the magnetic marker 16 is placed at the right end, the magnetic marker 14.
15.16 moves in the direction shown by the arrow as the belt 4 runs, and when either of these magnetic markers 14, 15.16 passes through the alternating current magnetic field zone 17 in the shaded area, The detection coils 7a, 7 installed in
Different pulse voltage trains are induced in b and 7c, respectively. In FIG. 5, at time t1, the magnetic marker 14.1
5.16 is located on the straight line connecting A-A', and the magnetic marker enters the alternating current magnetic field band 17 generated by the excitation coils 5a5b installed on both sides of the belt 40 at time tl, so it is not magnetized. begins to generate magnetic flux. Then, time passes as →t3→t4, and at time t, the magnetic marker leaves the alternating current magnetic field band 17 and finishes generating magnetic flux. In the case of FIG. 5, the magnetic markers 14, 15, 16 generate magnetic flux between times t and t, which induces pulse voltages in the detection coils 7a, 7b, and 7c.

Examples of the pulse voltage train are shown in FIGS. 6(a) and 6(b).

FIG. 6(a) shows that when any of the magnetic markers 14, 15, 16 reaches a position on the straight line connecting B-B' at time t in FIG. The shape of the induced pulse voltage train is expressed by the combination of each magnetic marker and each detection coil. Similarly, FIG. 6(b) shows time 1 in FIG. magnetic marker 14
．． Figure 6 (→, (b) shows the pulse voltage train induced in the detection coils 7a, 7b, and 7c when one of 15.16 reaches a position on the straight line connecting c-c'. As shown, the pulse voltage induced in each detection coil differs depending on the change in the relative position between the detection coils 7a, 7b, 7c and the magnetic markers 14, 15, 16. Therefore, each magnetic marker can be identified by its position. The detection coils that generate the pulse voltage trains with the highest possible output levels are not always the same.

The present invention provides a magnetic marker in an alternating current magnetic field zone 17 on the belt 4.
The system selects a detection coil that generates the optimal pulse voltage train for article identification no matter what position it passes through, and performs signal processing only on the signal from that detection coil.
The procedure for processing a plurality of signals generated from the detection coils 7a7b and 7c will be described below. FIG. 7 is a schematic diagram showing a measurement system of an apparatus for explaining the signal processing method, and the same reference numerals are used for parts common to those in FIG. 1. In FIG. 7, the measuring device 8 includes comparators 18a, 18b, 18c, a detection coil selection circuit 19. It includes an arithmetic circuit 20. First, signals from detection coils 7a, 7b, and 7c are sent to comparators 18c and 18b, respectively.

At step 18c, the presence or absence of a pulse voltage train is determined, which is determined based on the cases shown in FIGS. 8(a), (b), and (C). FIGS. 8(a) to (C) are schematic diagrams that define a certain threshold voltage and show this threshold voltage and pulse voltage series, and here, as shown in FIG. 8(a), the pulse voltage If the output of the train exceeds a certain threshold, it is considered to be before the pulse voltage train, and if it does not exceed the threshold as shown in Figure 8 (b) and (C), it is considered that there is no pulse voltage train, and the presence or absence of the pulse voltage train is determined. is judged as 0.1. Then, to make a more reliable judgment, perform this check several times.

For example, Table 2 shows the results of determining the presence or absence of a pulse voltage when the detection coils 7a, 7b, and 7c are checked three times.

Table 2 Table 2 shows the results of 0.1 determination of the presence or absence of a pulse voltage train three times.In this case, the signal from the detection coil that was determined to be 1 (before the pulse voltage train) all three times was The detection coil selection circuit 19 in FIG. Items can be identified.

〔Effect of the invention〕

A magnetic marker in which a magnetic hysteresis curve exhibits a rectangular shape and a plurality of amorphous magnetic thin wires or ribbons having different coercive forces are selectively arranged in parallel in the longitudinal direction at desired intervals;
Alternatively, by using a detection element in which this magnetic marker is fixed to plastic or the like, attaching it to an article and passing an alternating magnetic field through it, the type of magnetic marker, that is, the article, can be detected by pattern recognition of the time-series pulse voltage train generated in the detection coil. In the case of identification, in the present invention, as described in the embodiment, multiple signals generated from multiple detection coils installed in the article identification device are passed through a comparator, respectively, and the comparator is used to pass the multiple signals generated from the multiple detection coils installed in the article identification device. The presence or absence of a pulse voltage train is determined several times depending on whether a pulse voltage is generated or not, and the signal that is determined to be before the pulse voltage train is sent through a selection circuit to the detection coil. In other words, the optimal detection coil is selected in the limited time until the article passes through the AC magnetic field band, and the signal from this detection coil is passed through an arithmetic circuit to read the pulse voltage train pattern, making it possible to identify the article. This allows for efficient and accurate operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the main part configuration of an article identification device to which the present invention is applied, and FIGS. 2(a) and (b) are partially peeled perspective views showing the configuration of a detection element using a magnetic marker. Figure 3 is a magnetic characteristic line diagram of magnetic thin wire, Figure 4 (the river is an alternating current magnetic field waveform diagram,
Figure 4(C) is a pulse voltage train diagram when using magnetic marker H, Figure 4(C) is a pulse voltage train diagram when using magnetic marker U, and Figure 5 is a magnetic marker, excitation coil, and detection coil. Fig. 6(a) is a schematic diagram showing the positional relationship between the two, Fig. 6(a) is a diagram showing the shape of a pulse voltage train due to the combination of a magnetic marker and a detection coil at a certain time, and Fig. 7 is a measurement system of an article identification device. A schematic diagram showing FIG. 8(a),
(Mirror) and (C) are schematic diagrams showing a threshold voltage pulse voltage train. 1.11. ■, 14.15.16: Magnetic marker 1
゜1b, 1c, 1i' magnetic thin wire, 2: article, 3: pulley,
4: Held, 5a, 5b: Excitation coil, 6: AC oscillator, 7a, 7b, 7c: Detection coil, 8: Measuring instrument,
9: Personal computer, l: Detection element, 13: Fixed plate, 17: AC magnetic field band, 18a, 18b, 18c
: Comparator, 19: Detection coil selection circuit, 20: Arithmetic circuit. Agent + Physician Yama Ro Iwao - - 1 Go - U Wake 7 - Car Figure 2 Figure 5 11811t3 Figure 6 (b) I want to do 41IL □ 0 ---- lI @ l reply (LJ - column gv

Claims (1)

[Scope of Claims] 1) A magnetic marker having a rectangular magnetic hysteresis curve and a plurality of amorphous magnetic thin wires or ribbons each having a different coercive force and selectively arranged in parallel in the longitudinal direction at a predetermined interval, or these. A detection element on which a magnetic marker is fixed is attached to an article, passed through an alternating current magnetic field band, and the type of magnetic marker is identified by pattern recognition of the pulse voltage train generated in multiple detection coils installed within this alternating magnetic field band. When performing signal processing for an article identification device, multiple signals of pulse voltage trains generated from multiple detection coils are passed through a comparator, and a 0.1 judgment is made based on whether or not a pulse voltage higher than a preset threshold voltage is generated. Next, the signal that is determined to have a pulse voltage train is passed through a detection coil selection circuit to select the corresponding detection coil, and then the signal from this selected detection coil is passed through an arithmetic circuit to read the pulse voltage train pattern. A signal processing method for an article identification device, characterized in that the calculated signal is passed through a personal computer to identify the article. 2) A signal processing method for an article identification device according to claim 1, characterized in that the 0.1 determination is made multiple times based on whether or not a pulse voltage higher than a threshold voltage is generated.