JP2003084072A - Equipment for detecting metal, and method of regulating balance for equipment for detecting metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow balance of induced voltages in bi-axial two-pairs of respective detecting heads to be regulated easily. SOLUTION: In this metal detecting equipment having coaxial detection heads 30 and opposed type detection heads 40 for generating magnetic fluxes orthogonal each other, there are provided with a common area L1 where respective generated magnetic fields of the coaxial detection heads 30 and the opposed type detection heads 40 are crossed, and an independent area L2 extended up to an outside of an area where the generated magnetic fields of the opposed type detection heads 40 are not affected by the generated magnetic fields of the coaxial detection heads 30 and adjacent to the common area L1. The induced voltages in respective reception coils 32, 33 of the coaxial detection heads 30 are balanced by a coaxial side regulation part 51 arranged in the common area L1, and the induced voltages in respective reception coils 42, 43 of the opposed type detection heads 40 are balanced thereafter by an opposed side regulation part 52 arranged in the independent area L2.

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 a metal substance mixed in an object to be inspected, and more particularly to a metal detector provided with an adjusting mechanism for adjusting the balance of magnetic flux.

[0002]

2. Description of the Related Art A metal detector determines whether or not a metal is mixed in an object to be inspected by detecting a change in the inspection magnetic field caused by the metal mixed in the object to be inspected. FIG. 4 is a diagram showing the detection principle of the detection head in the metal detector. As shown in FIG. 4, conventionally, for example, the receiving coils 32 and 33 are arranged in front of and behind the central transmitting coil 31, and magnetic force lines parallel to the passing direction of the object W to be inspected (direction A in FIG. 4) are generated. A coaxial detection head 30 having a head coil arrangement for generation is used.

In the detection head 30, each coil 31,
In the inspection space S continuous inside 32 and 33, the induced voltages V1 having opposite phases to the receiving coils 32 and 33 that intersect with the magnetic flux due to the alternating magnetic field of the transmitting coil 31 in the center, respectively.
V2 is generated. The receiving coils 32 and 33 are arranged at the same distance with respect to the transmitting coil 31, and in the non-detection state in which the inspection object W is far from the inspection space S, the induced voltages V1 and V2 have the same magnitude and no difference. Becomes

For example, the object W to be inspected containing the metal M is
When it advances in the direction A in FIG. 4 and moves into the front receiving coil 32, the magnetic flux density in the receiving coil 32 increases, and conversely, the magnetic flux density in the receiving coil 33 decreases. Therefore, the induced voltage V1 of the receiving coil 32 becomes larger than the induced voltage V2 of the receiving coil 33. Then, when the inspected object W that has advanced to the inside of the receiving coil 33, the magnetic flux density inside the receiving coil 33 becomes larger than inside the receiving coil 32, so that the induced voltage V2 becomes larger than the induced voltage V1.
In this way, based on the change in the difference between the induced voltages V1 and V2 output from the detection head 30 (fluctuation of the magnetic field),
It is possible to determine whether or not the metal M is mixed in the inspection object W that has passed through the inspection space S.

In general, the detection head 30 is arranged so that a transfer conveyor (not shown) penetrates through the inspection space S, and is housed inside a substantially box-shaped casing 35 shown in FIG. . The housing 35 is formed of a magnetic shield material such as metal (eg, aluminum alloy or stainless steel). Then, the object W to be inspected is conveyed by the conveyor to pass through the inspection space S.

In the above structure, the difference between the induced voltages V1 and V2 in the receiving coils 32 and 33 does not become 0 in the non-detection state due to an error in manufacturing / assembling, and the balance of the induced voltage may be disturbed. is there. Therefore, the metal M cannot be detected accurately. Therefore, balance adjustment is necessary. In the conventional balance adjustment, as shown in FIG. 5, a metal plate 36, which is a magnetic material or a non-magnetic material, is attached to a portion of the inspection space S of the housing 35, or a magnetic material or a non-magnetic material is provided on the outer side. The balance was adjusted by inserting the metal rod 37 (for example, a screw). The adjustment with the metal plate 36 is performed by changing the attachment position with respect to the housing 35 and fixing the position at which the induced voltage is balanced. For the adjustment with the metal rod 37, the insertion depth with respect to the housing 35 is changed and fixed at a position where the induced voltage is balanced.

[0007]

By the way, the coaxial type detection head 3 used in the above-mentioned conventional metal detector is used.
In 0, for example, with respect to the needle-shaped or thin-plate-shaped metal M, the magnetic body, which is the metal M having the above-described shape, is arranged substantially orthogonal to the magnetic flux,
Alternatively, when the non-magnetic material, which is the metal M having the above-described shape, is mixed in the object W to be inspected in an arrangement parallel to the magnetic flux, the change in the magnetic flux is small, so that the difference between the induced voltages V1 and V2 is small and the detection sensitivity decreases. I will end up. That is, the metal M mixed in the inspection object W may not be detected.

Therefore, as shown in FIG.
A biaxial two-set metal detector using a detection head 40 whose magnetic flux direction is orthogonal to 0 together with the detection head 30 can be considered. As shown in FIG. 6, the detection head 40 has, for example, a transmission coil 41 arranged above the detection head 30 and arranged side by side reception coils 42 and 43 below the detection head 30 facing the transmission coil 41. The head coil is arranged so as to generate a magnetic force line orthogonal to the passing direction of the object W to be inspected (direction A in FIG. 4). The detection head 40 generates induced voltages V3 and V4 having opposite phases in the transmission coils 42 and 43 that intersect with the magnetic flux of the alternating magnetic field of the transmission coil 41 in the inspection space S. The receiving coils 42 and 43 are arranged at the same distance from the transmitting coil 41, and the induced voltages V3 and V4 have the same magnitude and no difference in the non-detection state.

In this metal detector, as shown in FIG.
The detection head 30 generates a horizontal magnetic flux, and the detection head 40 generates a vertical magnetic flux. Even if the magnetic body, which is a needle-shaped or thin-plate-shaped metal M, is arranged substantially perpendicular to the magnetic flux with respect to the magnetic flux of the detection head 30,
On the 0 side, since the arrangement is parallel to the magnetic flux, the change in the magnetic flux increases, the difference between the induced voltages V3 and V4 is large, and the detection sensitivity is good. Further, even if the needle-shaped or thin-plate-shaped metal M, which is a non-magnetic material, is arranged parallel to the magnetic flux with respect to the magnetic flux of the detection head 30, the detection head 40 side is arranged orthogonal to the magnetic flux. Therefore, the change of the magnetic flux increases, the difference between the induced voltages V3 and V4 is large, and the detection sensitivity becomes good. Thus, the detection head 40 is the detection head 3
The detection head 30 detects the metal M which is difficult to detect by 0, and the detection head 30 detects the metal M which is difficult to detect by the detection head 40.

However, in the above-described biaxial / two-pair metal detector, even if an attempt is made to balance the induced voltage of the detection head 30 by the above-mentioned balance adjustment, the influence of the induced voltage balance in the detection head 40 is obtained. It's gone. On the contrary, when the balance adjustment is attempted to obtain the balance of the induced voltage in the detection head 40, the influence of the balance adjustment makes it impossible to obtain the balance of the induced voltage in the detection head 30.
As described above, in the biaxial / two-pair metal detector, it is difficult to obtain the balance of the induced voltages of the detection heads 30 and 40.

In order to solve the above problems, the present invention provides a metal detector that forms two sets of two-axis detection heads, and can easily adjust the balance of the induced voltage of each detection head. It is an object of the present invention to provide a balance adjustment method for a detector and a metal detector.

[0012]

In order to achieve the above object, the metal detector according to claim 1 of the present invention is an object to be inspected W.
Is a metal detector having both detection heads 30 and 40 for generating biaxial magnetic fields orthogonal to each other in an inspection space S in which is transported, wherein each of the one detection head 30 and the other detection head 40 is Area L1 where the generated magnetic fields of
(L1 ′) and the magnetic field generated by either the one detection head 30 or the other detection head 40 extends to the outside of the shared region L1 (L1 ′), and the shared region L1
An independent region L2 (L2 ′) adjacent to (L1 ′),
An adjustment unit arranged in the shared area L1 (L1 ′) to obtain the balance of the induced voltages of the receiving coils 32, 33 (42, 43) of either one of the one detection head 30 or the other detection head 40. 51 (52 ') and induction of the receiving coils 42, 43 (32, 33) of the other one of the one detection head 30 or the other detection head 40 arranged in the independent region L2 (L2'). And an adjusting unit 52 (51 ') for obtaining a voltage balance.

A metal detector according to a second aspect is the metal detector according to the first aspect, wherein each of the adjusting portions 51, 52 (5
1 ′, 52 ′) are arranged in a portion that does not participate in the examination space S, and the adjustment units 51, 52 (51 ′, 52 ′) are provided.
The shield member 55 is provided to shield the magnetic field between the shared region L1 (L1 ′) and the independent region L2 (L2 ′) of the above-mentioned region.

In the balance adjusting method for a metal detector according to a third aspect of the present invention, each detection head 3 for generating biaxial magnetic fields orthogonal to each other in an inspection space S in which an object to be inspected W is transported.
A method for adjusting the balance of a metal detector having both 0 and 40, which is a shared region L1 where the generated magnetic fields of the one detection head 30 and the other detection head 40 intersect.
At (L1 ′), each receiving coil 3 of either one of the one detection head 30 or the other detection head 40
After the induced voltage of 2, 33 (42, 43) is balanced, the generated magnetic field of either one of the one detection head 30 or the other detection head 40 causes the shared region L1 (L
1 ') Each receiving coil of either one of the one detection head 30 or the other detection head 40 in an independent area L2 (L2') that extends to the outside and is adjacent to the shared areas L1 and L1 '. It is characterized in that the induced voltage of 42, 43 (32, 33) is balanced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic view showing a detection head of a metal detector of the present invention. In the embodiments described below, parts that are the same as or equivalent to those of the conventional technique described above will be assigned the same reference numerals.

As shown in FIG. 1, the metal detector has two sets of respective detection heads 30 and 40 for generating magnetic fields of two axes orthogonal to each other in an inspection space S in which an object to be inspected W is transported. ing. In the present embodiment, one detection head 30 is configured as the coaxial detection head 30, and the other detection head 40
Are configured as the facing detection head 40.

In the coaxial type detection head 30, the reversely wound receiving coils 32 and 33 are arranged coaxially in the front and rear of the transmitting coil 31, respectively, and the passing direction of the object W to be inspected (see FIG. 1).
The head coil is arranged to generate magnetic lines of force parallel to the middle A direction). The coaxial detection head 30 includes the coils 3
A continuous inspection space S is formed inside 1, 32, and 33. The coaxial detection head 30 generates a magnetic flux in the left-right direction in FIG. 1 (see FIG. 6) by the alternating magnetic field of the transmission coil 31 in the inspection space S, so that the phase of each of the transmission coils 32 and 33 intersecting with this magnetic flux. Generate opposite induced voltages V1 and V2. Each receiving coil 32, 33 has
They are arranged at the same distance with respect to the transmission coil 31, and in the non-detection state, the magnitudes of the induced voltages V1 and V2 are equal and the difference is 0.

The opposed detection head 40 has a transmission coil 41 arranged on one side (upper side) of the coaxial detection head 30, and the coaxial detection head 30 faces the transmission coil 41.
Receiving coils 42 and 43 are arranged side by side on the other side (lower side) to form a head coil arrangement for generating magnetic force lines orthogonal to the passing direction of the object W to be inspected (direction A in FIG. 3). .
The opposed detection head 40 forms the inspection space S between the transmission coil 41 and the reception coils 42 and 43. The opposed detection head 40 generates a magnetic flux in the vertical direction (see FIG. 6) in FIG. 1 by the alternating magnetic field of the transmission coil 41 in the inspection space S, so that the transmission coils 42 and 43 that intersect the magnetic flux are phased with each other. Is the reverse induced voltage V3, V
4 is generated. The receiving coils 42 and 43 are arranged at the same distance from the transmitting coil 41, and the induced voltages V3 and V4 have the same magnitude and no difference in the non-detection state. In the inspection space S, the opposed detection head 40 generates a magnetic flux that is orthogonal to the magnetic flux of the coaxial detection head 30.

The detection heads 30 and 40 are arranged so that a transporting means such as a transporting conveyor (not shown) penetrates through the inspection space S, and is housed in a substantially box-shaped casing 35 shown in FIG. To be done. The housing 35 is formed of a magnetic shield material such as metal (eg, aluminum alloy or stainless steel). Then, the object W to be inspected is conveyed by the conveyor to pass through the inspection space S.

In the metal detector having the above structure, in the coaxial type detection head 30, when the object W to be inspected containing the metal M advances in the direction A in FIG. 1 by the conveying means and moves into the front receiving coil 32, The magnetic flux density in the receiving coil 32 increases, and conversely, the magnetic flux density in the receiving coil 33 decreases. Therefore, the induced voltage V1 of the receiving coil 32 is
3 is larger than the induced voltage V2. Then, when the inspected object W that has advanced to the inside of the receiving coil 33, the magnetic flux density inside the receiving coil 33 becomes larger than inside the receiving coil 32, so that the induced voltage V2 becomes larger than the induced voltage V1. In this way, the metal M is mixed into the object to be inspected W that has passed through the inspection space S based on the change in the difference between the induced voltages V1 and V2 output from the coaxial detection head 30 (fluctuation of the magnetic field). It is possible to determine whether or not there is.

In the opposed detection head 40, the object W to be inspected containing the metal M is conveyed by the conveying means A in FIG.
And the receiving coil 42 in front of the transmitting coil 41.
When moving between and, the transmitting coil 41 and the receiving coil 42
The magnetic flux density between them increases, and conversely the magnetic flux density between the transmitting coil 41 and the receiving coil 43 decreases. Therefore, the receiving coil 4
The induced voltage V3 of 2 is larger than the induced voltage V4 of the receiving coil 43. Next, when the advanced inspection object W moves between the transmission coil 41 and the reception coil 43, the transmission coil 41
Since the magnetic flux density between the receiving coils 43 is larger, the induced voltage V4 is larger than the induced voltage V3. In this way, based on the change in the difference between the induced voltages V3 and V4 (fluctuation of the magnetic field) output from the coaxial detection head 40,
It is possible to determine whether or not the metal M is mixed in the inspection object W that has passed through the inspection space S.

That is, in the metal detector of the present embodiment, when the metal M mixed in the object W to be inspected has a needle shape or a thin plate shape and is a magnetic material, the magnetic flux generated by the coaxial detection head 30 When the arrangement is substantially orthogonal, the arrangement is parallel to the magnetic flux generated in the opposed detection head 40. As a result, in the coaxial detection head 30, since the change in magnetic flux is small and the difference between the induced voltages V1 and V2 is small, the detection sensitivity of the metal M is lowered, but in the opposed detection head 40, the change in magnetic flux is large and the induced voltages V3 and V4. Since the difference is large, the detection sensitivity of the metal M becomes good. On the contrary, when the metal M of the magnetic material is also arranged in parallel with the magnetic flux generated in the coaxial detection head 30 in the shape of a needle or a thin plate, the opposed detection head 40 is used.
The arrangement is substantially orthogonal to the magnetic flux generated in. As a result, in the opposed detection head 40, since the change in the magnetic flux is small and the difference between the induced voltages V3 and V4 is small, the detection sensitivity of the metal M is lowered, but in the coaxial detection head 30, the magnetic flux is changed largely and the induced voltages V1 and V2 are reduced. Since the difference is large, the detection sensitivity of the metal M becomes good.

Furthermore, in the metal detector of this embodiment,
When the metal M mixed in the object W to be inspected has a needle shape or a thin plate shape and is a non-magnetic material and is arranged parallel to the magnetic flux generated in the coaxial detection head 30, the opposed detection head 40 is used.
The arrangement is substantially orthogonal to the magnetic flux generated in. As a result, in the coaxial detection head 30, since the change in magnetic flux is small and the difference between the induced voltages V1 and V2 is small, the detection sensitivity of the metal M is lowered, but in the opposed detection head 40, the change in magnetic flux is large and the induced voltages V3 and V4. Since the difference is large, the detection sensitivity of the metal M becomes good. Conversely, it is also needle-shaped or thin-plate shaped, and
When the non-magnetic metal M is arranged substantially orthogonal to the magnetic flux generated in the coaxial detection head 30, the opposed detection head 4
The arrangement is parallel to the magnetic flux generated at 0. As a result, in the opposed detection head 40, since the change in the magnetic flux is small and the difference between the induced voltages V3 and V4 is small, the detection sensitivity of the metal M is lowered, but in the coaxial detection head 30, the magnetic flux is changed largely and the induced voltages V1 and V2 are reduced. Since the difference is large, the detection sensitivity of the metal M becomes good.

As described above, the metal detector described above uses both the coaxial detection head 30 and the opposed detection head 40 whose magnetic fluxes are orthogonal to each other, so that the metal M ( Even if it is a magnetic substance or a non-magnetic substance, it is detected by the other detection head, and the metal M mixed in the inspection object W is detected without exception.

In the metal detector having the above structure, the difference between the induced voltages V1 and V2 in the receiving coils 32 and 33 does not become zero in the coaxial detection head 30 in the non-detection state due to an error in manufacturing and assembling. , In the opposite detection head 40, the induced voltages V3 and V4 in the receiving coils 42 and 43
May not be 0, and the balance of the induced voltage may be out of balance. As a result, the metal M cannot be detected accurately, and balance adjustment is required.

The metal detector of the present embodiment has the following balance adjusting mechanism. FIG. 2 is a perspective view showing the balance adjusting mechanism.

As shown in FIG. 2, in the metal detector described above, the magnetic field generated by the coaxial type detection head 30 (shown by a chain double-dashed line in FIG. 2) is generated by the opposed type detection head 40 (see FIG. 2).
It is arranged so as to intersect with each other (indicated by a one-dot chain line). As a result, the generated magnetic field of the coaxial detection head 30 forms a shared region L1 where the generated magnetic fields of the coaxial detection head 30 and the opposed detection head 40 intersect.

In the opposed type detection head 40, the coils 41, 42 and 43 are extended to the right side in FIG. As a result, in the magnetic field generated by the opposed detection head 40 (shown by the alternate long and short dash line in FIG. 2), the portion extending to a region not affected by the magnetic field generated by the coaxial detection head 30 forms an independent region L2 adjacent to the shared region L1. Eggplant

In the above structure, the housing 35 is provided with the adjusting portions 51 and 52. The adjusting portion is a metal rod made of a magnetic metal body (for example, iron) or a non-magnetic metal body (for example, aluminum alloy or stainless steel), and is preferably configured as a screw shown in FIG. In the adjustment section,
There is a coaxial side adjustment section (first adjustment section) 51 and an opposite side adjustment section (second adjustment section) 52.

The coaxial adjustment section 51 is used for the coaxial type detection head 3
It is mounted so as to be movable in the shared region L1 in the recess 35a formed in the housing 35 by passing through the generated magnetic field of the opposed detection head 40 so as to reach the shared region L1 which is the generated magnetic field of 0. ing. In the case where the coaxial adjustment section 51 is configured as a screw, the common area L is rotated by the rotation.
Move back and forth within 1.

The opposing side adjusting section 52 is provided in the opposing detection head 4
The generated magnetic field of 0 and the housing 3 are arranged so as to reach only in the independent region L2 extended from the generated magnetic field of the coaxial detection head 30.
In the recessed portion 35b formed in 5, the independent region L2 is movably attached. In the case where the opposite side adjustment portion 52 is configured as a screw, the rotation thereof causes the movement in the independent region L2 to move back and forth.

At the time of balance adjustment, first, the coaxial type detection head 30 forming the shared region L1 is engaged, and the coaxial side adjustment section 51 is moved. The coaxial adjustment unit 51 changes the magnetic flux generated by the coaxial detection head 30 due to the movement, and obtains the balance of the induced voltage between the receiving coils 32 and 33.
Next, the facing detection head 40 forming the independent region L2 is caught, and the facing side adjustment unit 52 is moved. Opposing adjustment section 5
2 gives a change in the magnetic flux generated by the opposed detection head 40 due to the movement thereof to obtain the balance of the induced voltage between the receiving coils 42 and 43.

In the balance adjustment, the shared area L1
When the induced voltage is balanced in the (coaxial-type detection head 30), the coaxial-side adjustment unit 51 passes through the magnetic field generated by the opposed-type detection head 40, so that the magnetic flux of the opposed-type detection head 40 is affected. However, when the induced voltage is balanced in the independent region L2 (opposed detection head 40) next, the independent region L2 is independent of the shared region L1 and therefore affects the magnetic flux of the coaxial detection head 30. There is no.
As a result, it is possible to balance the induced voltages of the coaxial detection head 30 and the opposed detection head 40. As described above, according to the balance adjustment mechanism described above, it is possible to easily adjust the balance of the induced voltages of the detection heads 30 and 40.

By the way, the magnetic flux in the shared area L1 (on the side of the coaxial detection head 30) is changed to the coaxial side adjusting portion 51 for balancing the induced voltage, and the magnetic flux in the independent area L2 (on the side of the opposed detection head 40). The opposing side adjustment unit 52 that gives a change to balance the induced voltage is both provided on the independent region L2 side. Further, the independent region L2 is extended to a portion that does not participate in the inspection space S through which the inspection object W passes. According to this configuration, the shared region L1 of the portion of the adjustment units 51 and 52 is provided between the magnetic fields of the shared region L1 and the independent region L2.
Member 5 for shielding between the magnetic field between the independent region L2 and the independent region L2
5 are provided. Similar to the case 35, the shield member 55 is formed in a plate shape from a magnetic shield material such as metal (eg, aluminum alloy or stainless steel). The regions L1 and L2 are provided so as to be divided in the housing 35.

As described above, when the shield member 55 is provided, the independent region L2 is magnetically separated from the shared region L1, and therefore, when the balance of the regions L1 and L2 is adjusted, mutual influences are reduced, The adjustment can be performed more easily. In addition, the shield member 55 allows the independent region L
Even if 2 is in a narrow range, the above effect can be obtained, and the metal detector having the above configuration can be downsized.

Another balance adjusting mechanism will be described below. FIG. 3 is a perspective view showing another balance adjusting mechanism.

As shown in FIG. 3, in the above-described metal detector, the magnetic field generated by the opposed detection head 40 (shown by the alternate long and short dash line in FIG. 3) is generated by the coaxial detection head 30 (see FIG. 3).
It is arranged so as to intersect with each other. Thereby, in the magnetic field generated by the opposed detection head 40,
The portion of the coaxial detection head 30 that intersects with the generated magnetic field forms a shared region L1 ′ where the generated magnetic fields of the coaxial detection head 30 and the opposed detection head 40 intersect.

In the coaxial detection head 30, the coils 31, 32 and 33 are extended to the right side in FIG. As a result, in the magnetic field generated by the coaxial detection head 30 (indicated by a chain double-dashed line in FIG. 3), a portion extending to a region not affected by the magnetic field generated by the opposed detection head 40 is adjacent to the shared region L1 ′. Make L2 '.

In the above structure, the housing 35 is provided with adjusting portions 51 'and 52'. The adjusting portion is a metal rod made of a magnetic metal body (for example, iron) or a non-magnetic metal body (for example, aluminum alloy or stainless steel), and is preferably configured as a screw shown in FIG. The adjusting unit includes a coaxial adjusting unit (first adjusting unit) 51 ′ and an opposite adjusting unit (second adjusting unit) 52 ′.

The opposing side adjusting portion 52 'is formed in the housing 35 by passing the generated magnetic field of the coaxial type detection head 30 extended so as to reach the shared region L1' which is the generated magnetic field of the opposed type detection head 40. The shared region L1 ′ is formed in the formed recess 35a.
It is mounted so that it can move inside. In the case where the opposite side adjusting portion 52 ′ is configured as a screw, the rotation thereof causes the common area L1 ′ to move back and forth.

The coaxial adjustment section 51 'is provided in the recess 35b formed in the housing 35 so as to reach only the independent region L2' which is the magnetic field generated by the coaxial detection head 30.
It is attached so that it can move inside 2 '. In the case where the coaxial adjustment section 51 ′ is configured as a screw, the rotation thereof moves the inside of the independent region L2 ′ forward and backward.

At the time of balance adjustment, first, the facing type detecting head 40 forming the shared area L1 'is engaged, and the facing side adjusting portion 52' is moved. The opposite side adjustment unit 52 ′ changes the magnetic flux generated by the opposite type detection head 40 due to the movement thereof to obtain the balance of the induced voltage between the reception coils 42 and 43. Next, the coaxial type detection head 30 forming the independent region L2 ′ is engaged, and the coaxial side adjustment unit 51 ′ is moved. The coaxial side adjusting unit 51 ′ moves to move the coaxial type detecting head 3
By changing the magnetic flux generated by 0, each receiving coil 32, 33
To obtain the balance of induced voltage between.

Upon the above balance adjustment, the shared area L
When obtaining the balance of the induced voltage in the 1 '(opposed detection head 40), the opposed adjustment unit 52' is set to the coaxial detection head 30.
Of the coaxial detection head 3 because it passes through the generated magnetic field of
Affects zero magnetic flux. However, the independent region L
When the induced voltage is balanced in the 2 '(coaxial detection head 30), the independent region L2' is independent of the shared region L1 ', so that the magnetic flux of the opposed detection head 40 is not affected. As a result, it is possible to balance the induced voltages of the coaxial detection head 30 and the opposed detection head 40. As described above, according to the balance adjustment mechanism described above, it is possible to easily adjust the balance of the induced voltages of the detection heads 30 and 40.

By the way, the opposing side adjusting portion 52 'for changing the magnetic flux in the shared area L1' (opposite type detection head 40 side) to balance the induced voltage and the independent area L2 (coaxial type detection head 30 side). The coaxial adjustment unit 51 'that changes the magnetic flux to balance the induced voltage is both provided on the independent region L2' side. In addition, the independent region L2 ′ is extended to a portion that does not participate in the inspection space S that allows the inspection object W to pass therethrough. With this configuration, the shared area L1 ′ and the independent area L
A shield member 55 is provided between the magnetic field of 2'and the magnetic field of the independent region L2 'and the shared region L1' of the parts related to the adjustment parts 51 'and 52'. Similar to the case 35, the shield member 55 is formed in a plate shape from a magnetic shield material such as metal (eg, aluminum alloy or stainless steel). Then, each region L in the housing 35
It is provided so as to divide 1'and L2 '.

As described above, when the shield member 55 is provided, the independent area L2 'is magnetically separated from the shared area L1', and therefore, when the areas L1 'and L2' are balanced, mutual influences are exerted. The number is reduced and the adjustment can be performed more easily. Further, the shield member 55 can obtain the above effect even when the independent region L2 ′ is in a narrow range, and the metal detector having the above configuration can be downsized.

[0046]

As described above, in the metal detector according to the present invention, the shared area where the magnetic field generated by one detection head and the magnetic field generated by the other detection head intersect, and one of the above generated magnetic fields extends outside the shared area. The extended area is obtained and the independent area adjacent to the shared area is obtained, and the respective areas are individually adjusted in balance by the adjusting units. As a result, when first adjusting the balance of the detection head in the shared area, it affects the magnetic flux of the detection head in the independent area, but then in adjusting the balance of the detection head in the independent area, it affects the magnetic flux of the detection head in the shared area. Since the balance adjustment can be performed without giving the above, it is possible to easily adjust the balance of the induced voltages of the detection heads of the two sets of two axes.

Further, since the independent region is magnetically separated from the shared region by providing a shield member for shielding between the magnetic fields of the shared region and the independent region, mutual influences are exerted when the balance of each region is adjusted. It is possible to make adjustments more easily. Furthermore, the above-described effect can be obtained by the shield member even if the independent region is in a narrow range, so that the metal detector having the above configuration can be miniaturized.

[Brief description of drawings]

FIG. 1 is a schematic view showing a detection head of a metal detector of the present invention.

FIG. 2 is a perspective view showing a balance adjusting mechanism.

FIG. 3 is a perspective view showing another balance adjusting mechanism.

FIG. 4 is a schematic view showing a detection head of a conventional metal detector.

FIG. 5 is a perspective view showing a conventional balance adjusting mechanism.

FIG. 6 is a schematic diagram showing two sets of two-axis detection heads.

[Explanation of symbols]

30 ... Coaxial detection head (one detection head), 32 ...
Reception coil, 33 ... Reception coil, 40 ... Opposed detection head (other detection head), 42 ... Reception coil, 43 ... Reception coil, 51 ... Coaxial side adjustment section (first adjustment section), 51 '
... Coaxial side adjusting part (first adjusting part), 52 ... Opposing side adjusting part (second adjusting part), 52 '... Opposing side adjusting part (second adjusting part), 55 ... Shield member, L1 ... Shared area, L1 '...
Shared area, L2 ... Independent area, L2 '... Independent area.

Continued front page    (72) Inventor Satoshi Mitani             5-10-10 Minamiazabu, Minato-ku, Tokyo Henri             Tsu Co., Ltd. (72) Inventor Shigeru Kuboji             5-10-10 Minamiazabu, Minato-ku, Tokyo Henri             Tsu Co., Ltd. F-term (reference) 2G005 CA03                 2G017 AA04 AD03 AD04                 2G053 AA21 AB21 BB03 BC02 BC14                       CA03 DA01 DA02 DA06 DB02

Claims (3)

[Claims] 1. A metal detector having both detection heads (30, 40) for generating magnetic fields of two axes orthogonal to each other in an inspection space (S) in which an object to be inspected (W) is transported, A shared area (L1 (L1 ′)) where the generated magnetic fields of the one detection head and the other detected head intersect, and the generated magnetic field of either the one detection head or the other detection head is the shared area. An independent region (L2 (L2 ')) extending to the outside and adjacent to the shared region
And each receiving coil (3) of either one of the one detection head or the other detection head disposed in the shared area.
2, 33 (42, 43)) for adjusting the balance of induced voltages, and one of the one detection head or the other detection head disposed in the independent region. Each receiving coil (4
2, 43 (32, 33)) adjusting unit (52 (51 ')) for obtaining the balance of the induced voltage, and a metal detector. 2. The adjusting units (51, 52 (51 ′, 5
2 ')) is arranged in a portion not related to the inspection space (S) and the shared region (L
The metal detector according to claim 1, further comprising a shield member (55) for shielding between a magnetic field of 1 (L1 ')) and the independent region (L2 (L2')). 3. A balance adjustment method for a metal detector having both detection heads (30, 40) for generating perpendicular two-axis magnetic fields in an inspection space (S) in which an object to be inspected (W) is transported. In the shared region (L1 (L1 ′)) where the generated magnetic fields of the one detection head and the other detection head intersect, either one of the one detection head or the other detection head Receiver coil (32, 33 (42, 4
3)) After obtaining the equilibrium of the induced voltage, the magnetic field generated by either one of the one detection head or the other detection head extends outside the shared region and is adjacent to the shared region. (L2 (L2 ')) is characterized by obtaining the balance of the induced voltage of each receiving coil (42, 43 (32, 33)) of either one of the one detection head or the other detection head. Balance adjustment method for metal detectors.