WO2018147264A1 - Magnetic flux leakage detecting device for magnetic body employing magnetic sensor, and magnetic flux leakage detecting method - Google Patents

Abstract

[Problem] To provide a magnetic flux leakage detecting device for a magnetic body, the characteristics of which are improved by using a tunneling magneto resistance (TMR) magnetic sensor at high-sensitivity as a magnetic sensor, and to provide a magnetic flux leakage detecting method. [Solution] This magnetic flux leakage detecting device comprises: a magnetizer 21 which excites a magnetic body 30; a magnetic sensor module 20 including a magnetic line sensor 10 formed by arranging in the shape of a line a plurality of TMR magnetic sensors for detecting magnetic flux leakage resulting from inclusions, flaws, voids or the like inside the magnetic body 30; and a bias applying means for applying a bias magnetic field in a magneto-sensitive direction of the magnetic line sensor 10; wherein the bias magnetic field is applied by the bias applying means in such a way that the sensitivity of the TMR magnetic sensor is in a high-sensitivity region, which is a linear region zone, beyond a low-sensitivity region in the vicinity of 0 Oersted in the magneto-sensitive direction of the TMR magnetic sensor.

Description

Leakage magnetic flux detection device and magnetic flux detection method of magnetic body using magnetic sensor

The present invention relates to an apparatus and a method for detecting leakage magnetic flux caused by internal inclusions, scratches, air gaps, etc. of a magnetic body using a magnetic sensor.

Conventionally, an inspection apparatus using a magnetic sensor detects magnetic characteristics such as leakage magnetic flux, but the inspection target includes a magnetic material or a non-magnetic material having magnetism. As magnetic sensors, there are known magnetic sensors using Hall elements, TMR (Tunneling Magneto Resistance) elements, and other elements. Patent Document 1 describes detecting a magnetic pattern printed with magnetic ink on paper sheets such as banknotes and securities, which are nonmagnetic materials, using a magnetic line sensor. The magnetic line sensor has a configuration in which a large number of magnetic sensor elements whose longitudinal direction is a magnetic sensing direction with respect to a magnetic material are arranged on a surface side of a circuit board at a narrow pitch perpendicular to the longitudinal direction of the sensor element. A permanent magnet for applying a bias magnetic field to each magnetic sensor element is disposed on the back side of the circuit board.

The invention described in Patent Document 1 provides a magnetic line sensor that can be applied not only to detect the presence of a magnetic pattern but also to detect a magnetic pattern by increasing the resolution. The sensor is formed by arranging a large number of magnetic sensors using magnetic sensor elements in which the magnetic sensing direction of the magnetic material is the longitudinal direction at a narrow pitch substantially perpendicular to the longitudinal direction of the magnetic sensor elements. This magnetic line sensor is used by being arranged so that the conveyance direction of the detected medium provided with the magnetic pattern coincides with the longitudinal direction of the magnetic sensor element.

Patent Document 2 discloses an invention relating to a leakage magnetic flux flaw detection method in which a magnetic field is detected using a magnetic sensor in detecting defects on the surface and inside of a thin steel plate that is a magnetic material. The present invention includes a magnetizer for magnetizing a specimen, a magnetic detection unit that detects a magnetic field generated due to a defect, and a probe for magnetic testing including a light emitting element corresponding to the magnetic detection unit, The present invention provides a magnetic field visualization sensor having a function of determining lighting of the light emitting element based on a calculation result of an output signal from a magnetic detection unit, and a magnetic flaw detection probe including the magnetic field visualization sensor. The present invention has a function of discriminating between a magnetic flux leaking from a magnetizer to a magnetic sensor and a magnetic flux leaking out of a specimen due to a defect in the specimen, and further allowing the defect to be visually recognized on the spot.

Japanese Unexamined Patent Publication No. 2016-57125

JP 2014-106165 A

The magnetic line sensor of Patent Document 1 is intended to detect a magnetic pattern printed with magnetic ink on a paper sheet that is a non-magnetic material. Nothing is described about the inspection for the foreign substances inherent in the production of the (steel plate). When the magnetic line sensor of Patent Document 1 is applied to inspection of internal inclusions, scratches, air gaps, etc. of magnetic bodies, the positional relationship between the magnetic body and the sensor and the elements so as to be accurately adapted to such inspections It is necessary to ingenuate the configuration and magnetic field application means. Further, in order to apply the leakage magnetic flux flaw detection method described in Patent Document 2 to inspection of internal inclusions, scratches, air gaps, etc. of magnetic materials, further ingenuity is required in substrate design, element configuration, magnetic field application means, etc. is necessary.

In the invention disclosed in Patent Document 1, the invention is described using a TMR magnetic sensor. However, the magnetic sensor used is not limited to this (see Paragraph 0028 of Patent Document 1). . In the invention disclosed in Patent Document 2, the invention is described using a Hall element. However, the magnetic sensor is not limited to a Hall element (see Paragraph 0014 of Patent Document 2). The Hall element has a good linearity sensitivity as a magnetic sensor, but has a disadvantage that the sensitivity is low and it is easily influenced by the ambient temperature. In contrast, the TMR magnetic sensor has high sensitivity and excellent temperature characteristics.
The present invention has been made under such circumstances, and a magnetic leakage flux detecting device having improved characteristics by using a TMR magnetic sensor as a magnetic sensor with high sensitivity, and leakage magnetic flux detection using the detecting device. A method is provided.

One aspect of the magnetic flux leakage detection device of the present invention is a magnetizer for exciting a magnetic material, and a magnetic flux leaking due to internal inclusions, scratches, air gaps, etc. of the magnetic material disposed opposite to the magnetic material. A magnetic sensor module having a TMR magnetic sensor to be detected, and bias applying means for applying a bias magnetic field in the magnetic sensing direction of the TMR magnetic sensor are provided. The bias applying unit preferably serves as the magnetizer, but may include a bias applying auxiliary unit such as a permanent magnet in addition to the magnetizer. The magnetic sensor module includes a wiring board on which the plurality of TMR magnetic sensors are mounted. In order to reduce the distance between the magnetic body and a sensor chip constituting the TMR magnetic sensor, the sensor chip is attached to the magnetic body. A plurality of them may be arranged along the end portion of the wiring board facing the surface of the wiring board. The TMR adjacent to the low-sensitivity region in the vicinity of 0 Oe (hereinafter sometimes referred to as “Oersted”) is applied to the TMR magnetic sensor by the bias applying unit so that the magnetic sensor module can be used with high sensitivity. The magnetic sensor may be applied so that the sensitivity of the magnetic sensor is in a high sensitivity region that is a linear region. In order to detect leakage magnetic flux in the vertical direction from the magnetic body, the plurality of TMR magnetic sensors may be arranged in a direction perpendicular to the moving direction of the magnetic body and excited in the moving direction. . In order to provide a bias magnetic field in the vicinity of the highest sensitivity of the magnetic sensor module, the magnetic sensor module may be disposed at a position appropriately separated from the center position between the N pole and the S pole of the magnetizer. good.

One aspect of the magnetic flux leakage detection method of the present invention is a method for detecting a leakage flux of the magnetic material using the leakage magnetic flux detection device configured as described above, wherein the magnetic material is magnetized by the magnetizer. At the same time, the bias applying means applies a bias magnetic field so that the sensitivity of the TMR magnetic sensor exceeds the low sensitivity region near 0 Oersted in the magnetic sensing direction of the TMR magnetic sensor and becomes a high sensitivity region in which the sensitivity of the TMR magnetic sensor is a linear region. It is characterized by applying.

The magnetic leakage flux detecting device of the present invention can improve the characteristics by using the TMR magnetic sensor as a magnetic sensor in a highly sensitive state, and can reliably detect the leakage flux of the magnetic material. According to the leakage flux detection method, the leakage flux of the magnetic material can be detected with high sensitivity using this leakage flux detection device.

1 is a cross-sectional view of a magnetic flux leakage detecting device according to a first embodiment. Sectional drawing explaining the excitation to a magnetic body and leakage flux detection by the leakage flux detection apparatus of FIG. The top view of the magnetic sensor module which comprises the magnetic flux leakage detection apparatus shown in FIG. The top view which expands and shows the TMR magnetic sensor and magnetic line sensor which are the sensor chips which comprise the magnetic sensor module shown in FIG. FIG. 4 is a circuit diagram of the magnetic sensor module shown in FIG. 3 and an image device connected to the magnetic sensor module. FIG. 6 is a circuit diagram of a magnetic sensor module according to a second embodiment and an image device connected to the magnetic sensor module. FIG. 3 is an output characteristic diagram of the magnetic sensor module according to Example 1 (applied magnetic field−40 Oe to 40 Oe). FIG. 3 is an output characteristic diagram of the magnetic sensor module according to Example 1 (applied magnetic field—0.5 Oe to 0.5 Oe). FIG. 3 is an output characteristic diagram of the magnetic sensor module according to Example 1 (applied magnetic field: 9.5 Oe to 10.5 Oe). FIG. 6 is a characteristic diagram illustrating an output voltage at the time of air gap detection in each sensitivity region of the magnetic sensor module according to the first embodiment. FIG. 6 is a waveform diagram of a detection signal when the magnetic line sensor that constitutes the magnetic sensor module according to the first embodiment detects a gap in the magnetic body. FIG. 6 is a distribution diagram of a bias magnetic field applied to a magnetic line sensor by a bias applying unit and a relationship diagram between an excitation yoke position and a magnetic flux density. Sectional drawing of the leakage magnetic flux detection apparatus which shows another Example of a magnetic body. The top view of the magnetic sensor module which shows a magnetic body as a cross section similarly to FIG.

The present invention uses a TMR magnetic sensor (referred to as a “magnetic line sensor”) arranged in a line to detect leakage magnetic flux caused by internal inclusions, scratches, air gaps, etc. of a magnetic material such as a thin steel plate. In addition to the detection device, the present invention relates to a method of detecting leakage magnetic flux of a magnetic material with high sensitivity by effectively utilizing the characteristics of the TMR magnetic sensor.

Embodiment 1 will be described below with reference to FIGS. 1 to 5 and FIGS.
As shown in FIG. 1, the leakage magnetic flux detection device in this embodiment uses a magnetizer 21 that excites a thin steel plate 30 that is a magnetic material, and leakage magnetic flux caused by internal inclusions, scratches, air gaps, and the like of the thin steel plate 30. A magnetic sensor module 20 (see FIG. 3) in which a magnetic line sensor 10 in which a plurality of TMR magnetic sensors 1 to be detected (see FIG. 4) are arranged in a line is mounted on the wiring board 5 and the magnetic sensing direction of the TMR magnetic sensor 1 are arranged. Bias applying means for applying a bias magnetic field. The magnetizer 21 also serves as the bias applying means. Further, 31 is a roll rotatable in the clockwise direction in FIG. 1, and is guided by this roll 31, and the thin steel plate 30 is conveyed in the right direction in FIG. 1 by a conveying device (not shown) including the roll 31. The
The magnetic sensor module 20 is shown in FIG. Formed on one side of the wiring board 5 is a magnetic line sensor 10 composed of a number of TMR magnetic sensors 1 arranged close to the edge. Since each TMR magnetic sensor 1 is configured as a sensor chip, it may be referred to as a sensor chip 1 below. At the time of measurement by the leakage magnetic flux detection device, the thin steel plate 30 as an object is arranged close to one side where the magnetic line sensor 10 including the plurality of TMR magnetic sensors 1 of the wiring board 5 is formed. Further, the wiring substrate 5 is formed with an amplifying unit 11 made of an amplifier IC or an amplifier chip. The position of the amplifying unit 11 is not particularly limited, but is preferably close to the magnetic line sensor 10. A terminal portion 7 is provided on the other side of the wiring board 5. The side on which the terminal portion 7 is provided is not limited, but in this embodiment, the magnetic line sensor 10 is provided on the opposite side of the side formed in proximity. A lead 18 extends from the terminal portion 7 to the outside of the magnetic sensor module 20, and a signal obtained by the magnetic line sensor 10 is transferred from the terminal portion 7 to the lead 18 via wiring inside the wiring board 5. Reportedly.
FIG. 4 shows an enlarged plan view of a part of the wiring board 5 on which the magnetic line sensor 10 composed of the arranged TMR magnetic sensors 1 is formed.
In FIG. 4, the leakage magnetic flux detection device needs to be brought close to the thin steel plate 30 to be conveyed, which is an object, at the time of measurement. In order to efficiently and effectively detect the magnetic characteristics and leakage magnetic flux of the thin steel plate 30, the end of each TMR magnetic sensor 1 is located on the edge of the wiring board 5, which is a component of the magnetic sensor module 20. Need to be close. In FIG. 4, the distance from the edge to the end is set to 0.05 mm.

As shown in FIG. 4, the magnetic line sensor 10 is formed by arranging a large number of TMR magnetic sensors 1 having the same configuration on the main surface of the wiring board 5 on a straight line at a narrow pitch. Each TMR magnetic sensor 1 is composed of a fixed resistor or a low-sensitivity TMR element 2 and a high-sensitivity TMR element 3 having the same configuration, and between both elements 2 and 3 in which output terminals OUT common to both elements 2 and 3 are connected in series. Formed and positioned at one end in the longitudinal direction of the TMR magnetic sensor 1, the power supply terminal VDD is connected to the high-sensitivity TMR element 3 and disposed at the one end side in the longitudinal direction, and the ground terminal GND is disposed at the low-sensitivity TMR element 2 is connected to the one end side (see FIG. 5).
Here, for example, the number of TMR magnetic sensors 1 in the magnetic line sensor 10 is 154, and the pitch in the width direction of the TMR magnetic sensor elements 2 and 3 in the magnetic line sensor 10 is 0.5 mm.
The other end side opposite to the one end in the longitudinal direction of the TMR magnetic sensor 1 coincides with the side where the wiring board 5 faces the thin steel plate 30. Each TMR magnetic sensor 1 is arranged in a line along a side facing the thin steel plate 30 of the wiring board 5 to constitute the magnetic line sensor 10.
The leakage magnetic flux detection device in the present embodiment amplifies the leakage magnetic flux information of the thin steel plate 30 obtained by the TMR magnetic sensor 1 and sends it from the terminal section 7 to the image processing device, and the leakage magnetic flux information sent by this image processing device. Can be imaged.

Next, the magnetic sensor module 20 will be further described with reference to a circuit wiring connection diagram of the magnetic sensor module 20 of FIG. 5 and a block diagram of an image processing apparatus constituted by an image processing unit and an image display unit.
In the magnetic line sensor 10, a power supply voltage is supplied from the power supply terminal VDD to each high-sensitivity TMR element 3, and a ground terminal GND is connected to each low-sensitivity TMR element 2.
Each TMR magnetic sensor 1 in the magnetic line sensor 10 is referred to as a channel (hereinafter sometimes referred to as “ch”), and is arranged from the channel 1 to the channel 154 from the top to the bottom in FIG. Then, this is expressed as 1ch, 2ch, 3ch, ..., 154ch.

In FIG. 5, an analog signal from the magnetic line sensor 10 is input from the output terminal OUT (see FIG. 4) of each TMR magnetic sensor 1 to each amplifier constituting the amplifying unit 11.
The output of each amplifier is input to each A / D converter of the A / D converter 12 of the image processing apparatus and is digitally converted. The digital signal digitally converted by the A / D conversion unit 12 is input to the image processing unit 13 to generate an image, and the generated image is displayed on the image display unit 17.
The image processing unit 13 normalizes the digitized TMR magnetic sensor output so as to eliminate variations among the channels 1 to 154, and quantizes the normalized digital signal between the maximum value and the minimum value. A gradation data generation unit 15 that generates gradation data by converting the image data, and an image generation unit 16 that generates an image based on the gradation data in each of the channels 1 to 154.

Next, with reference to FIG.1 and FIG.2, the detection method of the leakage magnetic flux of the magnetic body using the leakage magnetic flux detection apparatus mentioned above is demonstrated.
As shown in FIG. 1, a thin steel plate 30 as an object travels on a roll 31. The magnetizer 21 is disposed close to the thin steel plate 30 on the roll 31. The magnetic line sensor 10 is disposed between the excitation yoke N pole 22 and S pole 23 of the magnetizer 21. A magnetic body magnetic flux, that is, a magnetic field is formed inside the thin steel plate 30 by the excitation yokes 22 and 23. At this time, as shown in FIG. 2, if there is a non-magnetic inclusion 32 inside the thin steel plate 30, leakage magnetic flux is generated from that portion and is detected by the magnetic line sensor 10.

Next, as shown in FIG. 2 and FIG. 12, the magnetizer 21 also serves as a bias applying means for applying a bias magnetic field in the magnetic sensing direction of the TMR magnetic sensor 1 as shown in FIGS. However, the bias applying means may use another magnetizing device instead of the magnetizer 21, or a permanent magnet may be added as a bias applying auxiliary means in addition to the magnetizer 21.
In the method of detecting the leakage magnetic flux of the thin steel plate 30, the thin steel plate 30 is magnetized by the magnetizer 21, and the low sensitivity region near 0 Oersted in the magnetic sensing direction of the TMR magnetic sensor 1 by the magnetizer 21 also serving as the bias applying means. The bias magnetic field (spatial magnetic flux) is applied so that the sensitivity of the TMR magnetic sensor 1 is in a high sensitivity region that is a linear region.

Hereinafter, the characteristics of the magnetic sensor module 20 used for leakage flux detection will be described with reference to FIGS.
The output voltage of the TMR magnetic sensor 1 varies greatly depending on the applied magnetic field (Oe). FIG. 7 shows output characteristics of the magnetic sensor module 20 on which the TMR magnetic sensor 1 is mounted. The horizontal axis represents the magnetic field (Oe) applied to the TMR magnetic sensor 1 of the magnetic sensor module 20, and the vertical axis represents the output voltage (V) from the output terminal OUT (see FIG. 4) that reacts to the applied magnetic field. ing. 7, 8, and 9, the power supply voltage is 5 V, and the value obtained by multiplying the output of the TMR magnetic sensor 10 times by the amplifying unit 11 is described as the output voltage.
FIG. 7 shows the sensitivity characteristics in the region of the applied magnetic field −40 to 40 Oe. Among these sensitivity characteristics, a region of −2 to 2 Oe is a low sensitivity region, and the characteristic diagram of FIG. 8 is included in the region. Further, the region of 2 to 13 Oe is the high sensitivity region, and the characteristic diagram of FIG. 9 is included in the region. In this embodiment, the TMR magnetic sensor 1 is used in this high sensitivity region.

Next, the operation of the magnetic sensor module 20 when a gap (not shown) in the thin steel plate 30 is detected will be described. FIG. 10 shows the relationship between the output (vertical axis: output voltage) and the magnetomotive force (horizontal axis) at the time of air gap detection in each sensitivity region of the TMR magnetic sensor 1 of the magnetic sensor module 20. Here, a region showing high sensitivity is a region indicated by ●, and the TMR magnetic sensor 1 is used in this high sensitivity region as described above. FIG. 11 illustrates the state of the detection signal. When the leakage magnetic flux detection device is operated and guided by the roll 31 to transport the thin steel plate 30 in a predetermined direction (see FIG. 1), the leakage magnetic flux is passed when the gap passes. As a result, the output voltage of the magnetic line sensor 10 changes greatly, and a gap is detected.

12A is a distribution diagram of a bias magnetic field applied to the magnetic line sensor 10 in which the magnetizer 21 has the sensor chip 1 arranged, and FIG. 12B is a relationship diagram between the positions of the excitation yokes 22 and 23 and the magnetic flux density. is there. In FIG. 12, the magnetic field sensor 10 of the magnetic sensor module 20 has a high sensitivity where the sensitivity of the TMR magnetic sensor 1 adjacent to the low sensitivity region near 0 Oersted is in the linear region so that the magnetic line sensor 10 can be used with high sensitivity. It is applied so as to be a sensitivity region.
In order to detect the leakage magnetic flux in the vertical direction from the thin steel plate 30, the plurality of TMR magnetic sensors 1 constituting the magnetic line sensor 10 are perpendicular to the width direction of the thin steel plate 30, in other words, the moving direction of the thin steel plate 30. Is excited in the direction perpendicular to the width direction, in other words, the moving direction.
In order to give a bias magnetic field in the vicinity of the highest sensitivity of the magnetic line sensor 10, the magnetic sensor module 20 is located at a position slightly away from the center position between the N pole 22 and the S pole 23 of the magnetizer 21 (near the bias magnetic field 7Oe). In particular, the magnetic line sensor 10 is preferably arranged.
As described above, in summary, in this embodiment, in the method of detecting the leakage magnetic flux of the thin steel plate 30, the thin steel plate 30 is magnetized by the magnetizer 21, and the magnetism 21 near the 0 Oersted in the magnetic sensitive direction of the TMR magnetic sensor 1. A bias magnetic field is applied beyond the low sensitivity region so that the sensitivity of the TMR magnetic sensor 1 is a high sensitivity region that is a linear region. Thereby, the maximum sensitivity of the magnetic line sensor 10 can be extracted.

In addition, the magnetic body in a present Example is not limited to the above-mentioned thin steel plate 30, The processed goods of the thin steel plate 30 are also included. Specifically, for example, as shown in FIG. 13 and FIG. 14, a steel plate processed product 33 such as a can or a case formed from the thin steel plate 30 into a cylindrical shape or a bottomed cylindrical shape is also a target. The steel plate processed product 33 is supported on the rotary head 35 of the rotating device 34 so that the cylindrical axis coincides with the rotation axis, and the outer periphery of the magnetic line sensor 10 and the magnetizer 21 and the steel plate processed product 33 facing the magnetic line sensor 10. The planes are set so as to have the same arrangement relationship as in FIG. As shown in FIG. 14, when the steel plate processed product 33 is rotated by the rotating device 34, the magnetic line sensor 10 arranged in the rotation axis direction that is a direction perpendicular to the moving direction causes the surface of the steel plate processed product 33 to Scan to detect leakage flux. Similar to FIGS. 1 and 2, if there is a non-magnetic inclusion 32 in the steel plate processed product 33, this inclusion 32 can be detected. Similarly to FIGS. 10 and 11, the steel plate If there is a gap inside the processed product 33, this gap can be detected.
Furthermore, it goes without saying that the present invention can be applied to magnetic bodies other than steel plates.

Next, Embodiment 2 will be described with reference to FIG.
As in FIG. 5 for explaining the first embodiment, referring to the circuit wiring connection diagram of the magnetic sensor module 40 and the block diagram of the image processing apparatus constituted by the image processing section 44 and the image display section 48, the magnetic of this embodiment is described. The sensor module 40 will be described.
In the magnetic line sensor 10, two different types of TMR elements constitute one channel (indicated as ch in FIG. 6), and two output terminals OUT (see FIG. 4) are respectively connected to the same amplifier of the amplifier 42. Connected to two input terminals. In the pair of TMR elements, a power supply voltage is supplied from the power supply terminal VDD to the high sensitivity TMR element 3a, and a ground terminal GND is connected to the low sensitivity TMR element 2a. The other TMR element pair is supplied with a power supply voltage from the power supply terminal VDD to the low-sensitivity TMR element 2b, and the high-sensitivity TMR element 3b is connected to the ground terminal GND. That is, each of the channels 1 to 154 has a bridge structure, and the number of TMR magnetic sensors 1 in this embodiment is 154 ch × 2, that is, twice as many as 308 in comparison with the first embodiment.

The analog signal from the magnetic line sensor 10 is input from the output terminal OUT (see FIG. 4) of each TMR magnetic sensor 1 to each amplifier constituting the amplifying unit 42.
The output of each amplifier is input to each A / D converter of the A / D converter 43 of the image processing apparatus and is digitally converted. The digital signal digitally converted by the A / D conversion unit 43 is input to the image processing unit 44 to generate an image, and the generated image is displayed on the image display unit 48. The image processing unit 44 normalizes the digitized TMR magnetic sensor output so as to eliminate variations among the channels 1 to 154, and quantizes the normalized digital signal between the maximum value and the minimum value. A gradation data generation unit 46 that generates gradation data by converting the image data into a grayscale data, and an image generation unit 47 that generates an image based on the gradation data in each of the channels 1 to 154.
In this embodiment, a full-bridge structure has been described, but this structure can be operated differentially.

As described above, in the magnetic line sensor constituted by the TMR magnetic sensor as described in these embodiments, the detection of the leakage magnetic flux due to inclusions, scratches, air gaps and the like inherent in the magnetic material such as the thin steel plate is reliably and efficiently performed. Can be done.

DESCRIPTION OF SYMBOLS 1 ... TMR magnetic sensor 2, 2a, 2b ... Low sensitivity TMR element 3, 3a, 3b ... High sensitivity TMR element 5 ... Wiring board 7 ... Terminal part 10 ... Magnetic line sensor 11, 42... Amplification unit 12, 43... A / D conversion unit 13, 44... Image processing unit 14, 45. 47: Image generation unit 17, 48: Image display unit 20, 40: Magnetic sensor module 21: Magnetizer 22: Excitation yoke (N pole)
23 ... Excitation yoke (S pole)
DESCRIPTION OF SYMBOLS 30 ... Thin steel plate 31 ... Roll 32 ... Inclusion 33 ... Steel plate processed product 34 ... Rotating device 35 ... Rotating head

Claims (7)

1. A magnetizer for exciting a magnetic material; a magnetic sensor module having a TMR magnetic sensor disposed opposite to the magnetic material to detect leakage magnetic flux caused by internal inclusions, scratches, air gaps, etc. of the magnetic material; and the TMR magnetism A magnetic flux leakage detection apparatus using a magnetic sensor, comprising: a bias applying unit that applies a bias magnetic field in a magnetic sensitive direction of the sensor.
2. 2. The magnetic flux leakage using a magnetic sensor according to claim 1, wherein the bias applying unit serves as the magnetizer or includes a bias applying auxiliary unit in addition to the magnetizer. Detection device.
3. The magnetic sensor module includes a wiring board on which the plurality of TMR magnetic sensors are mounted. In order to reduce the distance between the magnetic body and a sensor chip constituting the TMR magnetic sensor, the sensor chip is attached to the magnetic body. A magnetic leakage flux detecting device using a magnetic sensor according to claim 1, wherein a plurality of the magnetic circuit boards are arranged along an end portion of the wiring board facing the surface of the wiring board.
4. The sensitivity of the TMR magnetic sensor adjacent to the low sensitivity region where the bias magnetic field applied to the TMR magnetic sensor by the bias applying means is near 0 Oersted is in a linear region so that the magnetic sensor module can be used with high sensitivity. 4. The magnetic leakage flux detection device for a magnetic body using the magnetic sensor according to claim 1, wherein the magnetic sensor is applied so as to be a high sensitivity region.
5. The apparatus detects a magnetic flux leakage by moving the magnetic body in a predetermined direction. In order to detect a magnetic leakage flux in a vertical direction from the magnetic body, the plurality of TMR magnetic sensors are perpendicular to the moving direction of the magnetic body. 5. The magnetic leakage flux detection device for a magnetic material using the magnetic sensor according to claim 1, wherein the magnetic flux leakage detection device uses the magnetic sensor according to claim 1.
6. In order to provide a bias magnetic field in the vicinity of the highest sensitivity of the magnetic sensor module, the magnetic sensor module is disposed at a position appropriately separated from the center position between the north pole and the south pole of the magnetizer. A magnetic flux leakage detecting device using the magnetic sensor according to any one of claims 1 to 5.
7. 7. A method for detecting a leakage magnetic flux of the magnetic material using the leakage magnetic flux detection device according to claim 1, wherein the magnetic material is magnetized by the magnetizer and the bias applying means is used. The bias magnetic field is applied so that the sensitivity of the TMR magnetic sensor exceeds the low sensitivity region near 0 Oersted in the magnetic sensing direction of the TMR magnetic sensor so that the sensitivity of the TMR magnetic sensor becomes a high sensitivity region that is a linear region. A magnetic flux leakage detection method using a magnetic sensor.
   

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