JPH11118765A - Metal detector and metal detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge whether a plurality of types of metals exist or not in a product and whether the amount is appropriate or not by generating a metal reaction signal in reaction to the metals and judging a signal level when a product is passed through a magnetic field and the product has the metals. SOLUTION: A product P is carried by a conveyor C and is passed between a transmission coil and reception coils 6 and 7 of a metal detection machine 1. When a product P has a metal, the metal affects a magnetic field E and the magnetic flux of the coils 6 and 7 becomes unbalanced, a difference is generated in an inducted voltage, and a voltage signal is inputted to a differential amplifier 10. The amplified differential signal passes through a phase discriminator 12 as a metal reaction signal and is outputted to a judging means 4. A level for judging the mixture of unneeded iron is set to a judgment level d1 by a level-setting means 3, and a judgment level for sealing a needed soup bag made of aluminum is set to d2. A signal level is compared with judgment levels d1 and d2 by the judging means 4. And, the mixture of iron and presence or absence of sealing of the soup bag made of aluminum are judged based on the result and are displayed in a bar graph.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal detector for detecting the presence or absence or amount of metal contained in a product, and a metal detection system using the same.

[0002]

2. Description of the Related Art Generally, a metal detector detects the mixing of an unnecessary metal that should not be contained in a product or a missing part of a necessary metal product that should be contained in a product. When a metal is contained in a product, a metal reaction signal generating circuit that generates a metal reaction signal in response to the metal, a signal level of the metal reaction signal is compared with a determination level, and based on the comparison result, Determination means for determining the mixing of unnecessary metals or the missing of necessary metal products.

[0003] For example, in the case of a food product in which an aluminum soup bag is included in a packed instant noodle product, the conventional metal detector performs the following operation depending on the object to be defective. . If the signal level of the metal reaction signal exceeds the first determination level, which is a detection criterion for the mixing of unnecessary metals, it is determined that metal such as unnecessary iron pieces is mixed in the food, and the product is determined to be defective. If the signal level of the metal reaction signal is lower than the second determination level, which is the detection standard for the required metal product, it is determined that the aluminum soup bag (metal product) required for food is out of stock and is defective. And

[0004]

However, the determination level of the metal detector is a single level, and a defective product containing unnecessary metals cannot be detected even if a necessary metal product is missing. That is, conventionally, it has not been possible to simultaneously detect the incorporation of the unnecessary metal in the product and the detection of the shortage of the required metal product with one metal detector. On the other hand, if two metal detectors having different determination levels are juxtaposed, space saving and cost reduction cannot be achieved.

[0005] Further, in the above-mentioned metal detector, when detecting whether or not a required metal product is one bag, only the presence / absence of the required metal product can be detected because the determination level is single as described above. However, it was not possible to eliminate the case where two or more necessary metal products entered the product.

The present invention solves the above problems and provides a metal detector and a metal detection system capable of determining the presence or absence of a plurality of types of metals in a product or the appropriateness of the amount of the same type of metal. It is intended to be.

[0007]

In order to achieve the above object, a metal detector according to one aspect of the present invention passes a product in a magnetic field, and when the product contains a metal, the metal detector detects the metal. A metal reaction signal generating circuit that generates a metal reaction signal by reacting, a signal level of the metal reaction signal is compared with a plurality of determination levels, and based on the comparison result, a plurality of types of metals in the product are determined. A determination means is provided for determining at least one of the presence or absence and the appropriateness of the amount of the same type of metal.

According to the metal detector, since a plurality of determination levels are provided for the metal reaction signal, the determination means can perform a plurality of determinations at the same time according to the magnitude of the signal level of the metal reaction signal. The presence or absence of multiple types of metals in the product,
Alternatively, the appropriateness of the amount of the same type of metal can be determined.

According to another aspect of the present invention, there is provided a metal detector for allowing a product to pass through a magnetic field and, when the product contains a metal, reacting to the material of the metal to generate a metal reaction signal. A signal generation circuit, a plurality of phase discriminators for discriminating the metal reaction signal for each phase according to the material of the metal, and a signal level of each metal reaction signal discriminated for each phase is provided according to the phase. In comparison with the determined determination level, a plurality of comparing means for outputting each comparison result, based on each of the comparison results, the presence or absence of a plurality of types of metals in the product,
A determination unit that determines whether the amount of at least one type of metal is appropriate; and a plurality of the determination levels are set in the comparison unit corresponding to the determination unit that determines whether the amount of metal is appropriate.

According to the above metal detector, the metal reaction signal is discriminated for each phase corresponding to the material of the metal, and a determination level is provided according to the phase. Since a plurality of determination units are provided, the determination unit can perform a plurality of determinations at the same time based on the determination level provided according to the type of the metal. At the same time, the determination can be made with high accuracy.

Preferably, the plurality of types of metals are an unnecessary metal that should not be included in a product and a required metal that should be included in a product. It is a necessary metal to be included in.

[0012] The metal detection system according to the present invention includes a conveyor for conveying a product made of food, and the above-described metal detector for detecting metal contained in food conveyed by the conveyor. The contained metal can be detected while being conveyed by the conveyor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a metal detection system using a metal detector according to the first embodiment of the present invention. In this system, a metal detector 1 is arranged on a production line for transporting and producing a product P on a conveyor C. The metal detector 1 allows the product P to be included in the product P while being transported on the conveyor C. Metal to be detected.

The metal detector 1 applies a magnetic field E to the conveying path of the conveyor C, passes the product P through the magnetic field E, and reacts to the metal when the product P contains metal. A metal reaction signal generating circuit 2 for generating a metal reaction signal;
Phase discriminator 12 for discriminating the metal reaction signal into a predetermined phase
And a plurality of, for example, level setting means 3 for setting two determination levels d1 and d2, and comparing the signal level of the metal reaction signal with the plurality of determination levels d1 and d2, and based on the comparison result, Determining means 4 for determining the presence or absence of two types of metals in the product P; The comparison result is displayed by a display unit 16 such as a bar graph that displays a signal level based on the number of lighting of the arranged bars (FIG. 2). Further, the plurality of types of metals are unnecessary metals that should not be included in the product and required metals that should be included in the product.

The metal reaction signal generating circuit 2 includes a magnetic field generating unit 8 which generates an magnetic field E by supplying an exciting current to the transmitting coil 5.
And a magnetic sensor 9 formed by a pair of receiving coils 6 and 7 arranged at positions receiving equal amounts of magnetic fluxes of a magnetic field E generated from the transmitting coil 5 and the transmitting coil 5, and voltages from the receiving coils 6 and 7. And a differential amplifier 10 for inputting a signal. When the metal included in the product P passes through the magnetic field E, the magnetic flux intersecting the two receiving coils 6 and 7 becomes unbalanced, causing a difference in the induced voltages of the receiving coils 6 and 7, and a voltage signal having the difference. Is input to the differential amplifier 10, and
The differential signal is output from the differential amplifier 10 as a metal reaction signal.

Next, the operation of the present system will be described. The product in this system is, for example, a bag of instant noodle food, which detects the contamination of iron (Fe) which is an unnecessary metal that should not be contained in the bag, and at the same time, it is necessary that the product be contained in the bag. This is to detect a missing part of a soup bag made of metal (aluminum (Al)).

First, before performing metal detection by the present system, in order to increase the detection sensitivity of metal contamination, a phase discriminator 12 is used, for example, for input of both metal reaction signals of iron and aluminum. A well-known gain adjustment is performed in which the phase to be discriminated is set and the gain is adjusted so that an appropriate combined output is obtained.

In FIG. 1, a product P is conveyed by a conveyor C and passed between a transmission coil 5 and reception coils 6 and 7 of the metal detector 1. When a metal is contained in the product P, the metal affects the magnetic field E and the two receiving coils 6 and 7
Are imbalanced, and a difference occurs in the induced voltages of the receiving coils 6 and 7, and these voltage signals are input to the differential amplifier 10. The differential signal amplified by the differential amplifier 10 is output to the determination means 4 via the phase discriminator 12 as a metal reaction signal.

The level for judging unnecessary iron contamination by the level setting means 3 is set to a judgment level d1, and the level for judging that a necessary aluminum soup bag is contained in addition to unnecessary iron contamination is judged. The level is set to d2. The signal level of the metal reaction signal S is compared with the judgment levels d1 and d2 by the judging means 4, and based on the comparison result, as shown in the following (1) to (3), aluminum is mixed with Missing of the soup bag made of plastic is determined. The result of this comparison is displayed by the bar graph 16 in FIG.

(1) If the signal level of the metal reaction signal S is equal to or higher than the judgment level d2, the signal level is in zone 3 and the soup bag is contained, but it is judged that iron is also mixed. Product P is rejected. (2) If the signal level is equal to or higher than the determination level d1 and lower than d2, as shown in FIG. 2, the signal level is in zone 2 (shown in FIG. 50), and iron is not mixed, so that a soup bag is contained. The product P is determined to be a passed product. (3) If the signal level is less than the determination level d1, it is determined that no unnecessary metal is mixed in but the soup bag is not contained, and the product P is excluded.

As described above, the present system is provided with two determination levels d1 and d2 for one metal reaction signal S, so that the determination means 4 determines the product level in accordance with the signal level of the metal reaction signal S. It is possible to simultaneously determine the presence / absence of two types of metals, that is, determination of mixing of unnecessary metals in P and determination of missing required metal products.

When an aluminum (or other metal) ramen bag is also contained in addition to the above aluminum soup bag, it is determined at the same time that the unnecessary metal is mixed with the unnecessary metal product. When determining a shortage, the determination levels are d1 to d.
3 is set to three. The bag of the ramen noodles is not limited to aluminum and may be made of another metal.

When the size of the determination levels d1 and d2 is changed by using the above system, it is not determined whether or not unnecessary metal in the product P is mixed. It can be determined whether the bag is a bag, that is, whether the amount of the same type of metal is appropriate. In this case, the above-described gain adjustment is performed in accordance with the phase of the metal reaction signal of aluminum, and the level for determining one aluminum soup bag is determined by the level setting means 3 as the determination level d1.
The level for judging two or more soup bags is the judgment level d2.
(2 times d1).

If the signal level of the metal reaction signal S of aluminum is equal to or higher than the judgment level d2, it is judged that two or more soup bags are contained and the soup bag is excluded, and the signal level is equal to or higher than the judgment level d1 and lower than d2. If the signal level is less than the determination level d1, no soup bag is contained, so that the soup bag is excluded.

Next, a second embodiment will be described.
As shown in FIG. 3, the metal detector 1A used in the present system allows the product P to pass through the magnetic field E, and when the product P contains a metal, generates a metal reaction signal in response to the metal. A metal reaction signal generating circuit 2A. The metal reaction signal generating circuit 2A is different from the first embodiment in that a plurality of first and second differential amplifiers 10A and 10B are provided.

The metal detector 1A includes first and second phase discriminators 12A and 12B for discriminating the metal reaction signal for each phase corresponding to the metal, and a judgment level D1 for each phase of the metal reaction signal. And D2 and D3, respectively, and first and second level setting means 3A and 3B, and the signal levels of the respective metal reaction signals discriminated for each phase are determined by decision levels D1 and D2 provided according to the phase. , D3 and the first and second comparing means 14 for outputting each comparison result.
A, 14B, and determination means 4A for determining the presence or absence of a plurality of types of metals in the product P and determining whether or not the amount of at least one type of metal is appropriate based on each of the comparison results. The second corresponding to the determination means 4A for determining whether the amount of the metal is appropriate.
A plurality of determination levels D2 and D3 are set in the comparing means 14B.

Next, the operation of the present system will be described. This system is, for example, similar to the first embodiment, an instant noodle in which a product P is packed in a bag, and detects the intrusion of iron (magnetic material), which is an unnecessary metal, in the bag, and at the same time, in the bag, This is for detecting whether or not one aluminum soup bag (non-magnetic material), which is a necessary metal product, is one bag.

First, before performing metal detection by the present system, the metal reaction between iron and aluminum is performed using the first and second phase discriminators 12A and 12B in order to increase the metal detection sensitivity as described above. The gain is adjusted according to the phase to be discriminated so that an appropriate output is obtained for the signal input. In this example, since it is necessary to eliminate the inclusion of a small amount of iron, the gain of the metal reaction signal of iron is largely adjusted.

In FIG. 3, if the metal is contained in the product P conveyed by the conveyor C, the induced voltages of the receiving coils 6 and 7 differ as described above. The voltage signals having these differences are input to the first and second differential amplifiers 10A and 10B, amplified, and output as metal reaction signals to the first and second phase discriminators 12A and 12B, respectively.

The iron metal reaction signal S1 is supplied to the first phase discriminator 1
By 2A, the metal reaction signal S2 of aluminum is discriminated by the second phase discriminator 12B for each phase according to the material of iron and aluminum. As shown in FIG. 4, for example, the phase of the metal reaction signal S1 of iron (magnetic substance) is about 30 ° with respect to the phase of the signal supplied to the transmission coil 5, and the metal reaction signal of aluminum (nonmagnetic substance) The phase of S2 is about 90 °.

The signal level of the iron metal reaction signal S1 is changed by the first comparison means 14A shown in FIG.
Is compared with the determination level D1 set by the first level setting means 3A in accordance with the phase (here, 30 °), and the signal level of the metal reaction signal S2 of aluminum is determined by the second comparison means 14B. The phase of the signal S2 (here, 9
0 °) is compared with a plurality of determination levels D2 and D3 set by the second level setting means 3B. Judgment level D
2 is set to a level for judging whether or not one aluminum soup bag is set, and the judgment level D3 (twice D2) is set to the soup bag 2
It is set to a level that determines whether there is more than one. As shown in FIG. 4, the determination level D2 for the metal reaction signal S2 of aluminum is larger than the determination level D1 of the metal reaction signal S1 for iron.

Based on the result of the comparison, the judging means 4A shown in FIG. 3 determines whether or not one aluminum soup bag is present together with iron as shown in [1] to [6] below. Is determined. FIG. 5 shows the determination result.

[1] If the signal level of the metal reaction signal S2 of aluminum is not less than the judgment level D2 and less than D3 (aluminum, yes),
If the signal level of the metal reaction signal S1 of iron is less than the determination level D1 (iron, nothing), one soup bag is contained and no iron is mixed, so that the product P is determined to be an acceptable product (illustrated). 51). [2] The signal level of the metal reaction signal S2 of aluminum is equal to or more than the judgment level D2 and less than D3 (aluminum, existence), and the signal level of the metal reaction signal S1 of iron is equal to or more than the judgment level D1 (iron, existence).
In this case, although one soup bag is contained, it is determined that iron is mixed, and the product P is excluded (illustration 52). [3] If the signal level of the metal reaction signal S2 of aluminum is less than the determination level D2 (aluminum, nothing) and the metal reaction signal S1 of iron
If the signal level is less than the determination level D1 (iron, nothing), it is determined that iron is not mixed in but the soup bag is not contained, and the product P is excluded (illustrated 53). [4] If the signal level of the aluminum metal reaction signal S2 is less than the determination level D2 (aluminum, nothing), and the iron metal reaction signal S1
Is equal to or higher than the determination level D1 (iron, present), it is determined that the soup bag is not contained and iron is mixed, and the product P is removed (illustration 54). [5] If the signal level of the aluminum metal reaction signal S2 is equal to or higher than the determination level D3 (aluminum, nothing), and the iron metal reaction signal S1
If the signal level is less than the determination level D1 (iron, nothing), it is determined that two or more soup bags are contained although iron is not mixed, and the product P is excluded (FIG. 55). [6] If the signal level of the metal reaction signal S2 of aluminum is equal to or higher than the determination level D3 (aluminum, nothing), the metal reaction signal S1 of iron
Is equal to or higher than the determination level D1 (iron, present), it is determined that two or more soup bags are contained and iron is mixed, and the product P is excluded (illustration 56).

In addition, using the above-described system, when an aluminum ramen bag is contained in addition to the aluminum soup bag, the judgment level is set to four of D1 to D4.
At the same time as the detection of the mixing of the unnecessary metal, the appropriateness of the amount of the necessary metal product can be detected. The other bag may be made of another metal instead of aluminum, but in this case, the metal reaction signal is discriminated for each phase corresponding to the metal material, and the signal level is provided according to the phase. The appropriateness of the amount of the metal is determined by comparing the determined plurality of determination levels.

As described above, the invention of the second embodiment is as follows.
The presence or absence of a plurality of types of metals in the product P and the suitability of at least one type of metal can be simultaneously determined, and each metal reaction signal is discriminated for each phase, and the signal level is determined according to the phase. Since the determination is made by comparing with the provided determination level, the determination accuracy is higher than in the first embodiment.

[0036]

As described above, according to the metal detector according to the present invention, since a plurality of determination levels are provided for the metal reaction signal, the determination means determines the signal level of the metal reaction signal. Accordingly, a plurality of determinations can be made at the same time, so that the presence or absence of a plurality of types of metals in a product or the suitability of the amount of the same type of metal can be determined.

According to the metal detector according to another aspect of the invention, the metal reaction signal is discriminated for each phase corresponding to the material of the metal, a determination level is provided according to the phase, and the appropriateness of the amount of the metal is determined. Since a plurality of determination levels are provided, the determination means can perform a plurality of determinations at the same time based on the determination levels provided according to the type of metal. Appropriateness of the amount can be simultaneously and accurately determined.

Further, according to the metal detection system of the present invention, there are provided a conveyor for conveying a product made of food, and the above-mentioned metal detector for detecting a metal contained in food conveyed by the conveyor. Therefore, the metal contained in the food can be detected while being conveyed by the conveyor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a metal detection system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a display state of a metal reaction signal.

FIG. 3 is a configuration diagram illustrating a metal detection system according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a phase and a determination level of a metal reaction signal.

FIG. 5 is a diagram showing a determination result.

[Explanation of symbols]

1, 1A: metal detector, 2, 2A: metal reaction signal generation circuit, 4, 4A: determination means, C: conveyor, d1, d2
D1 to D3: judgment level, E: magnetic field, P: product.

Claims (5)

[Claims] 1. A metal reaction signal generating circuit for causing a product to pass through a magnetic field and generating a metal reaction signal in response to the metal when the product contains the metal, and a signal level of the metal reaction signal. A plurality of determination levels, and based on the comparison result, a determination unit that determines at least one of the presence or absence of a plurality of types of metals in the product and the appropriateness of the amount of the same type of metal. Equipped metal detector. 2. A metal reaction signal generating circuit for causing a product to pass through a magnetic field and generating a metal reaction signal in response to a material of the metal when the product contains a metal; A plurality of phase discriminators for discriminating each phase according to the material of the material, and comparing the signal level of each metal reaction signal discriminated for each phase with a determination level provided according to the phase, A plurality of comparison means for outputting a result; anda determination means for determining whether or not a plurality of types of metals are present in the product based on each of the comparison results, and determining whether the amount of at least one type of metal is appropriate. The metal detector in which a plurality of the determination levels are set in the comparison means corresponding to the determination means for determining whether the amount is appropriate. 3. The metal detector according to claim 1, wherein the plurality of types of metals are unnecessary metals that should not be included in a product and necessary metals that should be included in a product. 4. The metal detector according to claim 1, wherein the one kind of metal for which the appropriateness of the amount of the metal is determined is a necessary metal to be included in a product. 5. A metal detection system comprising: a conveyor for conveying a product made of food; and a metal detector according to claim 1 for detecting metal contained in the food conveyed by the conveyor. .