JP2015007580A - Magnetic sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic sensor device capable of accurately adjusting a minute bias magnetic field in a magnetic sensitive direction of an MR element by a simple method.
A magnet portion that faces one surface of a detected object having a magnetic component and forms a crossing magnetic field that intersects the detected object, and between one magnetic pole of the magnet portion and the detected object. And a magnetoresistive effect element that outputs a change in the transport direction component of the crossing magnetic field due to the magnetic component of the detected object transported in the crossing magnetic field as a change in resistance value, and the magnet unit includes: The crossing magnetic field applied to the magnetoresistive effect element is disposed so as to be movable relative to the magnetoresistive effect element in the transporting direction so that the component in the transporting direction has a predetermined magnitude.
[Selection] Figure 1

Description

  A magnetoresistive effect element (hereinafter referred to as an MR element) is arranged in the magnetic field distribution formed by the magnet, and the change in the magnetic field distribution caused by the passage of a magnetic material such as a banknote containing magnetic ink passes through the magnetic field. The present invention relates to a magnetic sensor device that detects an element.

  Japanese Patent Application Laid-Open No. 2008-145379 (see Patent Document 1) describes a ferromagnetic sensor that is linearly or substantially folded back in a magnetic sensor that detects a weak magnetic flux change caused by movement of a detection object such as a magnetic material. The ferromagnetic thin film comprising a substrate on which at least one body thin film magnetoresistive element is disposed and a permanent magnet for applying a bias magnetic field to the ferromagnetic thin film magnetoresistive element, and simultaneously providing a magnetic field for detection by the permanent magnet A magnetic sensor is described in which the position of the permanent magnet is adjusted so that the bias magnetic field intensity in the magnetosensitive direction of the magnetoresistive element is equal to or less than the saturation magnetic field.

  Japanese Utility Model Laid-Open No. 2-123042 (see Patent Document 2) discloses a permanent magnet that generates a constant magnetic field around a sensor, which is a magnetic sensor that detects a magnetic object by detecting a change in magnetic field around the sensor using a magnetoelectric transducer. Is mounted in a vacant space of the sensor case, and a detection position accuracy adjusting device for a magnetic sensor provided with a slide adjusting screw for changing the relative positional relationship between the permanent magnet and the magnetoelectric transducer by the sliding is described. Yes.

JP 2008-145379 A Japanese Utility Model Publication No. 2-123042

  In Patent Document 1, a bias magnetic field is generated for a magnetoresistive element in which a detection magnetic field generated by a permanent magnet is generated at the same time. The bias magnetic field of the permanent magnet is adjusted to an appropriate magnitude for the operation of the MR element. Although it is described that the position is adjusted, there is a problem that a specific adjustment mechanism is not shown.

  In Patent Document 2, there is a problem that a specific relative positional relationship between a magnetoelectric conversion element and a permanent magnet to be adjusted by a detection position accuracy adjusting device is not shown.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetic sensor device capable of accurately adjusting a minute bias magnetic field in the magnetosensitive direction of an MR element by a simple method. And

A magnetic sensor device according to the present invention faces one surface of a detected object having a magnetic component, and has different magnetic poles alternately in a direction perpendicular to the transport direction of the detected object, and intersects the detected object. The crossed magnetic field is conveyed by the magnetic component of the detected object that is provided between the magnet part that forms the crossing magnetic field, the one magnetic pole of the magnet part, and the detected object and is transported in the crossed magnetic field. A magnetoresistive effect element that outputs a change in direction component as a change in resistance value;
The magnetoresistive element is provided within the length of the magnet part in the transport direction of one magnetic pole, and is shifted from the center of the magnet part in the transport direction length of the magnetic pole in the transport direction,
The magnet portion is disposed so as to be movable relative to the magnetoresistive element in the transport direction so that a component in the transport direction of the cross magnetic field applied to the magnetoresistive element has a predetermined magnitude. It is what.

  Since the relative position of the magnet in the transport direction with respect to the MR element is adjusted using a screw in the transport direction, the position of the magnet can be easily finely adjusted, so that the bias magnetic field in the transport direction applied to the MR element can be adjusted. Can be adjusted with high accuracy by a simple method.

It is a schematic block diagram of the magnetic sensor apparatus which concerns on Embodiment 1 of this invention. It is a magnetic force line distribution map of the magnetic sensor apparatus of FIG. It is a perspective view at the time of seeing diagonally the magnetic sensor apparatus which concerns on Embodiment 1 of this invention. It is a magnetic force line vector figure explaining the detection principle of the magnetic sensor apparatus in Embodiment 1 of this invention. It is a schematic block diagram of the magnetic sensor apparatus which concerns on Embodiment 2 of this invention. It is a magnetic force line distribution map of the magnetic sensor apparatus of FIG.

Embodiment 1 FIG.
1 is a schematic configuration diagram of a magnetic sensor device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes an object to be detected such as a banknote including a magnetic component such as magnetic ink, 2 denotes one side of the banknote 1, and has an N pole S pole in a direction perpendicular to the conveyance direction 30 of the banknote 1. 3 is a magnetic material component such as iron, 4 is placed on the iron 3, and is provided between one magnetic pole (N pole in FIG. 1) of the permanent magnet 2 and the bill 1. An MR element for detecting a change in the magnetic field, 5 is a substrate for transmitting an output signal of the MR element, 6 is a cover for protecting the MR element 4 and the substrate 5, 7 is a case, 8 is a screw, and 9 is a plunger. The MR element 4 is provided within the length of the N pole in the transport direction of the permanent magnet 2 and is shifted (offset) in the transport direction from the center of the length of the N pole in the transport direction. FIG. 2 is a magnetic force distribution diagram of the magnetic sensor device of FIG. 1, and in FIG. 2, 10 is a magnetic force line.

FIG. 3 is a perspective view of the magnetic sensor device according to Embodiment 1 of the present invention when viewed obliquely. The banknote 1 is conveyed in the direction of the arrow 30, that is, substantially parallel to the cover 6 and substantially perpendicular to the longitudinal direction of the cover 6 or the case 7 while being substantially in contact with the cover 6 by a conveying roller (not shown). The At this time, a magnetic component contained in the magnetic ink or the like of the banknote 1 causes a change in the magnetic field formed by the permanent magnet 2, and this change is detected by the MR element 4.
As an order of arrangement of main components, the MR element 4 is arranged between the permanent magnet 2 and the banknote 1 as the detected object.

  In order to read the magnetic component information contained in the banknote 1 with high resolution, the MR elements 4 are arranged in a plurality of lines at small intervals in a direction substantially perpendicular to the arrow 30 (that is, the longitudinal direction of the cover 6 or the case 7). And operates as a line sensor in which a plurality of MR elements 4 are arranged in a magnetic field generated by one permanent magnet 2.

  The permanent magnet 2 is magnetized in the vertical direction in FIGS. 1 and 2, and as shown in FIG. 2, the lines of magnetic force 10 emitted from the permanent magnet 2 enter the magnetic material component 3 and then exit into the air. At this time, the magnetic force lines 10 on the surface of the magnetic material part 3 are radiated into the air perpendicular to the surface of the magnetic material part 3. Therefore, if the MR element 4 is arranged in the vicinity of the surface of the magnetic material component 3, the magnetic field applied to the MR element 4 is large in the vertical direction (vertical direction in FIGS. 1 and 2) and horizontal (see FIGS. 1 and 2). 2), a very slight magnetic field is applied. The magnetic field to be applied in the horizontal direction in the MR element 4 is as small as about 2 mT in terms of magnetic flux density, and the above situation is very convenient for the MR element 4.

  The operation of the magnetic sensor device will be described. In FIG. 2, at the position where the MR element 4 is installed, a vertical direction component 12 having a large magnetic flux density is present, and at the same time, a small transport direction component 13 is also present. This is because the MR element is considered to be installed at a position slightly away from the central axis 15. By arranging in this way, a bias magnetic field in the transport direction of about 2 mT (millitesla) necessary for proper operation of the MR element 4 can be applied to the MR element 3.

  When the bill 1 passes through such a state, the magnetic field distribution changes. At this time, the direction of the magnetic flux vector 11 applied to the MR element 4 slightly changes. Even if this change is slight, a large change in the conveyance direction component occurs as a percentage, and the MR element 4 can sufficiently detect this change.

  Detailed operation will be described with reference to FIGS. FIG. 4 is a magnetic force vector diagram for explaining the detection principle of the magnetic sensor device according to the first embodiment of the present invention. In FIG. 2, the magnetic field lines 10 are mainly composed of a component directed to the vertical direction of the iron 3, which is a crossing magnetic field that intersects the transport path, in the vicinity where the MR element 4 is disposed. Since it is slightly away from the axis 15 in the x-axis direction, as shown in FIG. 4A, the magnetic flux vector 11 of the magnetic field lines 10 is slightly inclined in the transport direction (x-axis direction) from the vertical direction (z-axis direction). The magnetic field transport direction (x-axis direction) component acts as a bias magnetic field of the MR element 4.

As the bill 1 approaches, as shown in FIG. 4B, the magnetic flux vector component 13 (Bx) in the transport direction (x-axis direction) because the magnetic flux vector 11 is inclined toward the bill 1 so as to be attracted to the bill 1. When the bill 1 becomes smaller and the bill 1 moves away, the magnetic flux vector component in the transport direction (x-axis direction) since the magnetic flux vector 11 is tilted toward the bill 1 so as to be pulled by the bill 1 as shown in FIG. By increasing 13 (Bx), the resistance value of the MR element 4 that senses the x-axis direction component changes, and the banknote 1 can be detected. That is, the passage of the banknote 1 changes the magnetic flux vector component 13 (Bx) in the transport direction (x-axis direction), so that the resistance value of the MR element 4 that senses the x-axis direction component changes and the banknote 1 is detected. can do. In FIG. 4B and FIG. 4C, the dotted arrow that intersects the magnetic flux vector 11 indicates the position of the magnetic flux vector 11 in FIG.

  That is, since the change of the magnetic flux vector 11 is caused by the passage of the banknote 1, the passage of the banknote 1 can be detected by adopting such a configuration. As a result, it is possible to provide a magnetic sensor device capable of reading a slight magnetic field change caused by the banknote 1.

  In order to apply a horizontal magnetic field (bias magnetic field) of an appropriate magnitude to the MR element 4, it is necessary to adjust the positional relationship between the MR element 4 and the permanent magnet 2. Therefore, the screw 8 and the plunger 9 for pushing the permanent magnet 2 are used in combination. Since the plunger 9 always applies a force so as to press the permanent magnet 2 against the screw 8, the tip of the permanent magnet 2 is always moved regardless of which direction the screw 8 is pushed or pulled. Touching.

  As a result, it is possible to freely adjust the position of the permanent magnet 2 in a direction substantially parallel to the conveyance direction of the banknote 1 (the direction of the arrow 30) simply by turning the screw 8. At this time, by selecting the screw pitch of the screw 8, the relationship between the angle at which the screw 8 is rotated and the moving distance of the screw 8 can be selected. Therefore, the screw pitch may be selected in accordance with the desired adjustment accuracy.

  When the bill 1 passes through the vicinity of the MR element 4 in the magnetic field configured as described above, the direction of the magnetic flux applied to the MR element 4 slightly changes as described above. Although this change is slight, the horizontal component becomes a large change as a ratio, and this change can be detected by the MR element 4, so that a magnetic sensor device with excellent sensitivity can be provided.

  In the first embodiment of the present invention, the plunger 9 is used to press the permanent magnet 2 against the screw 8. However, this may be achieved by simply using a spring or a corresponding elastic member. Similar effects can be obtained. Moreover, not only the elastic member but also it is effective to arrange two screws on both sides as a set.

Embodiment 2. FIG.
FIG. 5 is a schematic configuration diagram of a magnetic sensor device according to Embodiment 2 of the present invention. Even in the case of the configuration in which the permanent magnet 2 and the circuit portion such as the MR element 4 are separated as shown in FIG. 5, the same operational effects as those of the first embodiment of the present invention can be obtained. In FIG. 5, 20 a and 20 b are yokes attached so as to sandwich the permanent magnet 2, 21 is a screw that supports the permanent magnet 2, 22 is a case that accommodates the MR element 4, IC, and the like, and 23 is a banknote 1 or the like to be detected It is a space for objects to pass through. In FIG. 5, the same or equivalent components as those in FIG.

  FIG. 6 is a magnetic field distribution diagram of the magnetic sensor device of FIG. A conveyance roller (not shown) such as a banknote is attached so as to push or pull out the banknote 1 into the gap 23, and the banknote 1 passes through the gap 23. As an order of arrangement of main components in the second embodiment of the present invention, a bill 1 as an object to be detected is arranged between the permanent magnet 2 and the MR element 4. At this time, since the bill 1 changes the magnetic field generated by the permanent magnet 2, this can be detected by the MR element 4. Also in the second embodiment of the present invention, as in the first embodiment of the present invention, the magnetic sensor device operates as a line sensor.

  In this configuration as well, it is necessary to adjust the positional relationship between the MR element 4 and the permanent magnet 2 in order to apply a horizontal magnetic field of appropriate strength to the MR element 4. Therefore, the combination of the screw 8 and the plunger 9 is used as in the first embodiment of the present invention.

  If the permanent magnet 2 and the circuit portion such as the MR element 4 are separated as in the second embodiment of the present invention and the gap 23 through which the object to be detected such as the banknote 1 passes is made large, the banknote 1 The detected object such as can pass without strongly contacting the magnetic sensor device. Accordingly, there is an advantage that the wear of the contact portion of the magnetic sensor device is less and the reliability is improved.

  In the second embodiment of the present invention, the plunger 9 is used to press the permanent magnet 2 against the screw 8. However, this is the same even when a spring or a corresponding elastic member is used. The effect is obtained. Further, not only the elastic member but also a combination of a set of screws is effective.

1 banknote (object to be detected)
2 Permanent magnet 3 Iron (magnetic material parts)
4 MR element 5 Substrate 6 Cover 7 Case 8 Screw 9 Plunger 10 Magnetic lines 11, 12, 13 Magnetic flux vector 15 Center line 20a, 20b Yoke 22 Case 23 Air gap 30 Transport direction

Claims (12)

A magnet unit facing one surface of a detected object having a magnetic component, having magnetic poles alternately different in a direction perpendicular to the transport direction of the detected object, and forming a crossing magnetic field intersecting the detected object; The change in the resistance value is a change in the cross direction magnetic field conveyance direction component due to the magnetic component of the detection object that is provided between one magnetic pole of the magnet unit and the detection object. A magnetoresistive effect element that outputs as
The magnetoresistive element is provided within the length of the magnet part in the transport direction of one magnetic pole, and is shifted from the center of the magnet part in the transport direction length of the magnetic pole in the transport direction,
The magnet portion is disposed so as to be movable relative to the magnetoresistive element in the transport direction so that a component in the transport direction of the cross magnetic field applied to the magnetoresistive element has a predetermined magnitude. Magnetic sensor device. The adjustment mechanism which has the elastic part which contacted one side of a pair of side which opposes the conveyance direction of the magnet part, and the screw part which contacted the position of the other side facing the elastic part. The magnetic sensor device according to 1. Facing one surface of the detected object having a magnetic component, having different magnetic poles alternately in a direction perpendicular to the transport direction of the detected object, forming a crossing magnetic field intersecting the detected object, the transport direction The crossed magnetic field by the magnetic component of the detected object that is provided between the magnet part extending in a direction orthogonal to the magnetic field, the one magnetic pole of the magnet part, and the detected object and conveyed in the crossed magnetic field A change in the transport direction component is output as a change in resistance value, and includes a plurality of magnetoresistive elements arranged in an array in a direction perpendicular to the transport direction,
The magnetoresistive element is provided within the length of the magnet part in the transport direction of one magnetic pole, and is shifted from the center of the magnet part in the transport direction length of the magnetic pole in the transport direction,
The magnet portion is disposed so as to be movable relative to the magnetoresistive element in the transport direction so that a component in the transport direction of the cross magnetic field applied to the magnetoresistive element has a predetermined magnitude. Magnetic sensor device. The adjustment mechanism which has the elastic part which contacted one side of a pair of side which opposes the conveyance direction of the magnet part, and the screw part which contacted the position of the other side facing the elastic part. 3. The magnetic sensor device according to 3. The magnetic sensor device according to claim 4, wherein a plurality of the adjustment mechanisms are provided in a direction orthogonal to the transport direction. A magnet portion facing one surface of the detected object having a magnetic component and having different magnetic poles alternately along the transport direction of the detected object, and facing the other surface of the detected object, the transport direction And a magnetic body that is arranged to face the magnet section and generates a crossing magnetic field that is formed between the magnet section and intersects the detected object, and a side of the magnetic body facing the detected object A magnetoresistive effect having a magnetosensitive effect in the transport direction in which a change in the transport direction component of the magnetic field due to the magnetic component of the detected object transported in the cross magnetic field is output as a change in resistance value. With elements,
The magnet portion is disposed so as to be movable relative to the magnetoresistive element in the transport direction so that a component in the transport direction of the cross magnetic field applied to the magnetoresistive element has a predetermined magnitude. Magnetic sensor device. The adjustment mechanism which has the elastic part which contacted one side of a pair of side which opposes the conveyance direction of the magnet part, and the screw part which contacted the position of the other side facing the elastic part. 6. The magnetic sensor device according to 6. A magnet portion facing one surface of the detected object having a magnetic component and having different magnetic poles alternately along the transport direction of the detected object, and facing the other surface of the detected object, the transport direction And a magnetic body that is arranged to face the magnet section and generates a crossing magnetic field that is formed between the magnet section and intersects the detected object, and a side of the magnetic body facing the detected object In addition, a change in the transport direction component of the magnetic field due to the magnetic component of the detected object that is mounted in a plurality of arrays in a direction orthogonal to the transport direction and transported in the crossing magnetic field is defined as a change in resistance value. A magnetoresistive element having a magnetosensitive effect in the conveying direction to output,
The magnet portion is disposed so as to be movable relative to the magnetoresistive element in the transport direction so that a component in the transport direction of the cross magnetic field applied to the magnetoresistive element has a predetermined magnitude. Magnetic sensor device. The adjustment mechanism which has the elastic part which contacted one side of a pair of side which opposes the conveyance direction of the magnet part, and the screw part which contacted the position of the other side facing the elastic part. 9. A magnetic sensor device according to 8. The magnetic sensor device according to claim 9, wherein a plurality of the adjustment mechanisms are provided in a direction orthogonal to the transport direction. The magnet unit is provided with magnets having different magnetic poles alternately along the conveyance direction of the detected object, and a pair of yokes formed of a magnetic body are provided on the magnetic poles on both side surfaces perpendicular to the magnet conveyance direction, The magnetic sensor device according to claim 6, wherein the elastic portion or the screw portion is in contact with the yoke. The magnetic sensor device according to any one of claims 2, 4, 5, 7, and 9 to 11, wherein the elastic portion is a plunger.

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