JP2005300228A - Long-length type magnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a magnetic substance pattern of an object to be detected in full length in the direction (longitudinal direction) perpendicular to the moving direction of the object to be detected and resolve a problem of error in correction quantity of position shift and a problem of variation of distance between the magnetic sensing part and the object to be detected in the case that a plurality of magnetic resistance elements have a staggered arrangement. <P>SOLUTION: Magnetic resistance elements 2 are arranged in a chessboard pattern so that the magnetic sensing part 20 of a plurality of magnetic resistance elements 2 crosses the moving direction M of the object to be detected and form two rows in a plane parallel to the magnetic sensing part 20. Each magnet is arranged so that one plane of the nearly rectangular shape magnet 5 making two rows becomes parallel to the plane of the magnetic sensing part. They are arranged so that the end parts overlap the adjacent magnetic sensing part 20 to each other, and the end parts of the magnetic sensing part 20 overflow from the end position of the magnet 5 or the end part of the magnetic sensing part 20 coincide with the end position of the magnet 5 when the magnetic sensing part 20 is seen from the moving direction of the object to be detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a long magnetic sensor that detects a magnetic pattern printed on, for example, banknotes.

  Patent Documents 1 and 2 are disclosed as magnetic sensors for identifying an object to be detected such as a bill or a securities printed with a predetermined pattern with magnetic ink or the like. The configuration of the long magnetic sensor disclosed in Patent Document 1 is shown in FIG. (A) of the same figure is the top view which looked at the magnetic sensing part side in the state which removed the cover, (B) is sectional drawing of the BB part in (A). In this example, the magnetoresistive elements (MR elements) 2a to 2e are each provided with a magnetic sensitive part 20. These magnetoresistive elements 2 a to 2 e are arrayed and fixed to the case 1. An object to be detected is conveyed in a direction orthogonal to the longitudinal direction of such a long magnetic sensor 200.

  FIG. 9 is a front view showing a structure under the magnetoresistive element and a state of a magnetic field applied to the magnetoresistive element. However, only three magnetoresistive elements 2b to 2d are shown here. Magnets 5b to 5d are respectively arranged below the magnetoresistive elements 2b to 2d so that the magnetic flux penetrates in a direction perpendicular to the magnetoresistive elements 2b to 2d.

  FIG. 9B shows a state in which magnetic bodies (magnetic inks) 101c, 101cd, and 101d as objects to be detected are positioned in the vicinity of the long magnetic sensor. However, this does not mean that 101c, 101cd, and 101d arrive at the same time or sequentially with a time difference, but only that they may arrive at this position independently. As described above, when the magnetic bodies 101c, 101cd, and 101d are interposed in the magnetic field of the magnets 5c and 5d, the magnetic flux is concentrated in these magnetic body portions and the magnetic flux density penetrating the magnetic sensitive portions 20c and 20d is increased. As a result, the resistance value of the magnetoresistive element increases, whereby the presence or absence of the magnetic bodies 101c, 101cd, 101d is detected.

  However, most of the magnetic flux toward the magnetic body 101cd located at the center of the two adjacent magnetic sensitive portions 20c and 20d does not pass through the magnetic sensitive portions 20c and 20d, but passes through the gap Gh portion therebetween. Since the change in the magnetic flux density passing through the gap Gh does not affect the magnetoresistive effect by the magnetic sensing portions 20c and 20d, the detection level (detection capability) near the gap Gh is lowered. FIG. 8C shows an example of detection level characteristics with respect to the longitudinal position of the long magnetic sensor.

  The long magnetic sensor in which such a detection level lowering position exists is inappropriate when it is required to detect a magnetic pattern over the entire surface of the object to be detected. Therefore, as disclosed in Patent Document 2, there are some in which magnets and magnetoresistive elements are arranged in a staggered manner in a plane parallel to the magnetic sensing portion of the magnetoresistive element.

  FIG. 10 shows the configuration of the long magnetic sensor. (A) of the same figure is the top view which looked at the magnetic sensing part side in the state which removed the cover. In this example, the magnetoresistive elements 2a to 2g are arranged in the case 1 so as to be staggered in a plane parallel to the magnetic sensing portion. Moreover, it is necessary for the magnets 5a to 5g to uniformly apply a magnetic field to the magnetoresistive elements 2a to 2g. On the other hand, the magnet generates a magnetic force more stably at the center than at the outer periphery. For this reason, magnets 5a-5g having a larger length and width than magnetoresistive elements 2a-2g as shown in FIG. 10A are used, and magnetoresistive element 2a is located near the center of each magnet. ~ 2g is arranged.

  Further, in the magnetoresistive elements 2a to 2g, objects to be detected are conveyed in a direction orthogonal to the longitudinal direction. For this reason, the magnetoresistive elements 2a to 2g are arranged so as to be continuous without generating a gap between the magnetic sensing parts when viewed in the moving direction of the object to be detected.

In this way, by arranging the plurality of magnetoresistive elements 2a to 2g and the magnets 5a to 5g in a staggered manner so as to form two rows, a substantially constant detection level can be obtained over the entire length in the longitudinal direction of the long magnetic sensor. It can be secured.
Japanese Patent No. 2912262 JP 2003-107142 A

  However, as shown in FIG. 10A, in the long magnetic sensor in which the magnetoresistive elements are arranged in a zigzag pattern in the plane parallel to the magnetic sensing portion, the two adjacent in the oblique direction. Only one gap L is generated in the moving direction of the detected object for each magnetoresistive element. For this reason, extra signal processing and data processing are required to correct a temporal shift corresponding to the L positional shift. In addition, there is a problem in that it is difficult to obtain a stable output because an error occurs in the positional deviation correction amount between the magnetoresistive elements in the moving direction of the detected object in accordance with the accuracy of the moving speed of the detected object.

  Further, the object to be detected is transported through rotation of a transport roller (not shown) located above the case of the long magnetic sensor. For example, the object to be detected may be uneven by bending or the like as represented by banknotes, and when the object passes through the center line CLsl of the magnetic sensing portion, which is the position to be detected earlier shown in FIG. There is a possibility that the distance between the magnetic sensing part and the object to be detected changes when passing through the center line CLs2 of the magnetic sensing part, which is the position detected by. When the distance between the magnetic sensing part and the object to be detected changes, the detection level changes. Therefore, proper gap adjustment between the transport roller and the long magnetic sensor is severe and difficult.

  For this reason, when arranging magnetoresistive elements and magnets in a staggered manner so as to form two rows, it is important to design the gap between the two rows as small as possible. there were.

  That is, as shown in FIG. 10B, the distance L in the moving direction of the detected object between the pair of the magnet 5 and the magnetoresistive element 2 is such that the magnets come into contact with each other on their side surfaces. ) Cannot be closer than indicated. Therefore, the distance L between the magnetoresistive elements in the moving direction of the object to be detected is also limited.

  The object of the present invention is to enable detection of the magnetic pattern of the object to be detected over the entire length (longitudinal direction) orthogonal to the direction of movement of the object to be detected, and to arrange a plurality of magnetoresistive elements in a staggered manner. An object of the present invention is to provide a long magnetic sensor that solves the problem of error in the amount of misalignment correction and the problem of change in the distance between the magnetic sensing part and the object to be detected.

In order to achieve the above object, the long magnetic sensor is configured as follows.
(1) A plurality of magnetoresistive elements having a magnetosensitive part formed on or near each surface, the longitudinal direction of the magnetosensitive part is perpendicular to the moving direction of the object to be detected, and the magnetosensitive part is in a plane. In a long magnetic sensor arranged in a zigzag pattern so as to form two rows, and a magnet for applying a magnetic field to the magnetoresistive element is arranged on the side opposite to the magnetosensitive part forming surface of the magnetoresistive element, The magnet has a substantially rectangular parallelepiped shape, and the magnet is arranged so that one surface of the magnet is parallel to the plane of the magnetic sensing portions forming the two rows, and the magnetic sensing portion is viewed in the moving direction of the detected object. End portions of adjacent magnetic sensing portions overlap each other, and the end portions of the magnetic sensing portions protrude from the position of the end surface substantially parallel to the moving direction of the detected object of the magnet, or are substantially equal to the end surfaces. It is configured as you do.

  (2) In (1), a plurality of magnets are used, each magnet is arranged in two rows in a plane parallel to the plane of the magnetic sensing portion, and part of the end faces of the magnets are arranged so as to face each other. The distance between the center lines of the two rows of magnets extending in the direction orthogonal to the moving direction of the object is made shorter than the distance between the center lines of the magnetoresistive elements.

  (3) In (1), a plurality of magnets are used, the end faces of adjacent magnets are arranged so as to face each other, and the center line of the magnet extending in a direction perpendicular to the moving direction of the detected object is a straight line. Each magnet is arranged so as to have a shape.

  (4) In (1) to (3), a plurality of magnetoresistive elements are arranged corresponding to one magnet.

  (5) In (1) to (3), when a magnet is provided for each magnetoresistive element and the magnetosensitive part is viewed in the moving direction of the object to be detected, the end of the magnetosensitive part of the adjacent magnetoresistive element is a magnet. Approximately match the position of the end face

  (6) In (1) to (5), a plurality of magnets are used, and a gap is provided between the end surfaces of the magnets adjacent to each other.

  (1) When the magnet is arranged so that one surface of the magnet is parallel to the plane of the magnetic sensing portions forming the two rows, and the magnetic sensing portion is viewed in the moving direction of the detected object, the adjacent magnetic sensitivity Since the ends of the parts overlap each other and the end of the magnetic sensing part protrudes from the position of the end face substantially parallel to the moving direction of the detected object of the magnet or substantially coincides with the end face, the detected object The distance L between the magnetoresistive elements in the detected object moving direction can be made as close as possible while maintaining the overlapping of the magnetosensitive parts of the magnetoresistive elements when viewed in the moving direction.

  (2) A plurality of magnets are arranged such that the horizontal plane faces the magnetoresistive element side and part of the end faces face each other, and these magnets are arranged in two rows in a plane parallel to the magnetic sensing part. In addition, since the distance between the center lines facing the longitudinal direction of the two rows of magnets is shorter than the distance between the center lines facing the longitudinal direction of the magnetoresistive element, the occupied width of the magnet in the moving direction of the object to be detected is reduced. Therefore, a small and long magnetic sensor can be constructed as a whole.

  (3) By arranging the center lines facing the longitudinal direction of the plurality of magnets to be linear, the width of the long magnetic sensor in the detected object moving direction can be minimized, and the plurality of magnets can be When it is arranged in the case, the structure of the magnet arrangement part of the case becomes simple and the price can be reduced.

  (4) The number of magnets can be reduced by arranging a plurality of magnetoresistive elements in a single magnet, or by arranging a plurality of magnetoresistive elements in at least one of the plurality of magnets, The structure of the case for mounting the magnet is simplified, the number of magnet assembly steps can be reduced, and the manufacturing cost can be reduced.

  (5) By providing a magnet for each magnetoresistive element and viewing the magnetosensitive part of the magnetoresistive element in the direction of movement of the object to be detected, by making the end of the magnetoresistive element substantially coincide with the position of the end face of the magnet, The length of the magnetically sensitive portion per dimension in the longitudinal direction of the long magnetic sensor perpendicular to the moving direction of the object to be detected can be shortened, and the cost can be reduced.

  (6) In each magnet alone, the vicinity of the two end faces facing each other has a stronger magnetic field strength than the center. However, in the place where the end faces of the adjacent magnets face each other, the magnetic field of the two magnets interferes. Strength decreases. Therefore, by providing an appropriate gap between the end surfaces of the magnets adjacent to each other, the strength of the magnetic field strength near the end surfaces of the magnets is offset by the action of decreasing the magnetic field strength due to the interference, and the detected object moves in the moving direction. On the other hand, a substantially uniform magnetic field intensity distribution can be obtained over the entire length in the longitudinal direction, and the detection level for the position in the longitudinal direction can be made more uniform. In addition, when storing the plurality of magnets in the case, a section for storing each magnet is provided, and the magnet is mounted in each section. Therefore, it is easy to position the mounting position of the plurality of magnets with respect to the case. Become.

The configuration of the long magnetic sensor according to the first embodiment will be described with reference to FIGS.
1A and 1B are external perspective views of a long magnetic sensor, in which FIG. 1A shows a state in the middle of attachment of a cover, and FIG. 1B shows an attachment state. The case 1 made of synthetic resin has a plurality of magnetoresistive elements 2a, 2b, 2c, 2d. Terminal pins 6 respectively connected to the plurality of magnetoresistive elements 2a, 2b, 2c, 2d,. Claw engaging grooves 3 are provided on both sides of the case 1 along the longitudinal direction.

The cover 4 made of metal is provided with a cover fixing claw portion that engages with the claw portion engaging groove 3 of the case. As shown, cover 4 is covered on top of case 1. The detected object 100 is conveyed in a direction orthogonal to the longitudinal direction of the long magnetic sensor 200 as indicated by an arrow in the figure.
The case 4 is provided with a cover terminal 11 for electrical ground connection to the circuit board.

  2A and 2B are diagrams showing an internal configuration of the long magnetic sensor shown in FIG. 1, wherein FIG. 2A is a plan view with the cover 4 removed, and FIG. 2B is a magnet viewed from the same direction. Only shows. (C) is sectional drawing of the CC section in (A).

  As shown in (A), the magnetic sensitive portions 20a, 20b, 20c,... (Hereinafter simply referred to as “magnetic sensitive portion 20”) are longitudinal in a direction orthogonal to the moving direction M of the detected object. The direction is formed on or near the surface of the magnetoresistive elements 2a, 2b, 2c (hereinafter simply referred to as “magnetoresistive element 2”). The object to be detected moves in a direction orthogonal to the longitudinal direction of the magnetic sensing unit 20. However, when the detected object 100 shown in FIG. 1 is a paper sheet such as a banknote, it is not always conveyed in a direction that is strictly perpendicular to the longitudinal direction of the long magnetic sensor 200. In some cases, the sheet is conveyed with some skew. The rows made of the magnetic sensitive portions 20a and 20c and the rows made of the magnetic sensitive portions 20b and 20d are arranged in a straight line in the same plane. Center lines CLs1 and CLs2 shown in (A) indicate straight lines extending in a direction orthogonal to the moving direction of the object to be detected in the magnetic sensitive portions of the respective rows.

  Further, as shown in (C), the magnetoresistive element 2 is located at the upper part of the case 1, and the magnets 5a, 5b, 5c,... (Hereinafter simply referred to as “magnet 5”) are located at the lower part of the case 1, respectively. The magnet 5 is attached to the magnetoresistive element 2 on the side opposite to the magnetic sensitive part 20. The magnets 5a and 5c and the magnets 5b and 5d are arranged so as to form a line in a straight line when viewed from a direction orthogonal to the moving direction of the detected object as shown in FIG. One magnetoresistive element 2 is arranged in each magnet 5. Moreover, center lines CLs1 and CLs2 shown in (A) also coincide with a straight line of the magnet 5 extending in a direction orthogonal to the detected object moving direction. In addition, the magnets 5 each have a rectangular parallelepiped shape, and are disposed in the case 1 so that one surface thereof is parallel to the plane of the magnetic sensing unit 20. Further, in this example, the magnets are arranged such that a part of the end face on the side perpendicular to the one surface and parallel to the moving direction of the object to be detected is opposed to each other. In FIG. 2B, the overlapping portion is indicated by w.

  In this embodiment, the magnetoresistive element 2 longer than the length of the magnet 5 in the longitudinal direction is used, and as a result, the end portion P of the magnetic sensitive portion 20 is disposed so as to protrude from the position of the end face of the magnet 5. For this reason, the magnets 5 can be arranged in a row so that the end faces face each other. In other words, the width L of the magnetoresistive elements 2 in two rows in the detected object moving direction can be sufficiently narrowed without being limited to the dimension of the magnet 5 in the detected object moving direction (width direction).

  3A and 3B are diagrams showing the configuration of the long magnetic sensor according to the second embodiment. FIG. 3A is a plan view seen from the magnetoresistive element side with the cover removed, and FIG. 3B is the same direction. Only the magnet seen from is shown. In the example shown in FIG. 2, a center line extending in a direction orthogonal to the detected object moving direction of each magnet 5 and a center line extending in a direction orthogonal to the detected object moving direction of each magnetoresistive element 2. The magnet 5 and the magnetoresistive element 2 are arranged so as to match. On the other hand, since the magnet 5 of FIG. 3 is a small magnet having a width shorter than that of FIG. 2, the center lines of the magnets inevitably do not coincide with each other, and the center line CLsl of the magnetoresistive element 2 does not coincide. , CLs2 is outside the center lines CLml, CLm2 of the magnet 5. In other words, the distance Lm between the center lines of the magnets 5 is shorter than the distance Ls between the center lines of the magnetoresistive element 2. In this structure, the width Lc of the detection object moving direction of the case l can be made smaller than that in FIG.

  FIG. 4 is a diagram showing the configuration of the long magnetic sensor according to the third embodiment, and is a plan view seen from the magnetoresistive element side with the cover removed. In this example, the magnets 5 are arranged so that their entire end faces face each other, and the center lines of the magnets are arranged in a straight line. Also in this structure, the width Lc in the moving direction of the object of the long magnetic sensor can be made smaller than the example shown in FIG.

  Moreover, in this example, since the storage part of the magnet 5 with respect to the case 1 forms a straight line and the structure is simple, there is an effect that the manufacturing cost of the case 1 can be reduced.

  FIG. 5 is a diagram showing the configuration of the long magnetic sensor according to the fourth embodiment, and is a plan view seen from the magnetoresistive element side with the cover removed. In this example, one magnet 5 is associated with every two magnetoresistive elements. That is, the magnet 5ab applies a magnetic field to the magnetoresistive elements 2a and 2b in a direction perpendicular to the paper surface. Similarly, the magnet 5cd applies a magnetic field to the two magnetoresistive elements 2c and 2d in a direction perpendicular to the paper surface.

  Thus, by arranging magnets corresponding to a plurality of magnetoresistive elements, the number of parts can be reduced, and the part cost and assembly cost can be reduced.

  In addition, not only two magnetoresistive elements but also a magnet may be arranged corresponding to each of a plurality of three or more magnetoresistive elements, and a magnetic field is generated by a single magnet for all the magnetoresistive elements. May be applied.

  FIG. 6 is a diagram showing the configuration of the long magnetic sensor according to the fifth embodiment, and is a plan view of the magnetoresistive element side with the cover removed. In the first to fourth embodiments, the end portion P of the magnetosensitive portion 20 formed in each magnetoresistive element 2 is disposed so as to protrude from the end surface of the magnet 5. On the other hand, in the fifth embodiment, both ends of the magnetic sensing portion 20 formed in each magnetoresistive element 2 are substantially matched with the position of the end face of the magnet 5.

  Even in this structure, the continuity of the magnetic sensing part when viewed from the moving direction of the object to be detected is maintained, and there is no portion where the detection level is lowered.

FIG. 7 is a diagram showing a configuration of a long magnetic sensor according to the sixth embodiment.
In this example, a gap G is provided between the adjacent end surfaces of each magnet 5. Where the end faces of adjacent magnets 5 are opposed to each other, the magnetic field strength is reduced due to the interference of the magnetic fields of the two magnets. Therefore, such a structure can compensate for the decrease in the magnetic field strength. Therefore, by providing an appropriate gap, a substantially uniform magnetic field intensity distribution can be obtained over the entire length in the longitudinal direction perpendicular to the moving direction of the object to be detected, and the detection level for the position in the longitudinal direction can be made more uniform. In addition, when storing the plurality of magnets in the case, sections for storing the respective magnets are provided, and the magnets are mounted in the sections. Therefore, it is easy to position the mounting positions of the plurality of magnets with respect to the case. It becomes.

External perspective view of a long magnetic sensor according to the first embodiment A plan view and a cross-sectional view showing a positional relationship between a plurality of magnetoresistive elements and a plurality of magnets of the long magnetic sensor The figure which shows the structure of the elongate type magnetic sensor which concerns on 2nd Embodiment. The figure which shows the structure of the elongate type magnetic sensor which concerns on 3rd Embodiment. The figure which shows the structure of the elongate type magnetic sensor which concerns on 4th Embodiment. The figure which shows the structure of the elongate type magnetic sensor which concerns on 5th Embodiment. The figure which shows the structure of the elongate type magnetic sensor which concerns on 6th Embodiment. The figure which shows the structure of the elongate type magnetic sensor currently disclosed by patent document 1, and the fluctuation | variation of the detection level by a position The figure which shows the example of magnetic flux density distribution of the same long magnetic sensor The figure which shows the structure of the elongate type magnetic sensor currently disclosed by patent document 2

Explanation of symbols

1-case 2-magnetoresistive element 3-claw engaging groove 4-cover 5-magnet 6-terminal pin 11-cover terminal 20-magnetic part 100-detected object 101-magnetic material (magnetic ink)
200-long magnetic sensor CLs-center line of magnetoresistive element L-interval between magnetoresistive elements in the moving direction of the object to be detected

Claims (6)

A plurality of magnetoresistive elements each having a magnetic sensing portion formed on or near each surface, the longitudinal direction of the magnetic sensing portion being orthogonal to the moving direction of the object to be detected, and the magnetic sensing portions in two rows in a plane In a long magnetic sensor arranged in a zigzag pattern so as to form a magnet that applies a magnetic field to the magnetoresistive element on the side opposite to the magnetosensitive part forming surface of the magnetoresistive element,
The magnet has a substantially rectangular parallelepiped shape, and the magnet is arranged so that one surface of the magnet is parallel to the plane of the magnetic sensing portions forming the two rows, and the magnetic sensing portion is viewed in the moving direction of the detected object. End portions of adjacent magnetic sensing portions overlap each other, and the end portions of the magnetic sensing portions protrude from the position of the end surface substantially parallel to the moving direction of the detected object of the magnet, or are substantially equal to the end surfaces. A long magnetic sensor characterized by   There are a plurality of magnets, and each magnet is arranged in two rows in a plane parallel to the plane of the magnetic sensing part, and the end surfaces of the magnets are arranged so as to face each other, and the object to be detected moves. The long magnetic sensor according to claim 1, wherein a distance between center lines of the two rows of magnets extending in a direction orthogonal to the direction is shorter than a distance between center lines of the magnetoresistive elements.   A plurality of the magnets are arranged such that the entire end surfaces of adjacent magnets face each other, and the plurality of magnets extend in a direction perpendicular to the moving direction of the detected object of the magnets. The long magnetic sensor according to claim 1, wherein the magnetic sensors are arranged so as to be linear.   The long magnetic sensor according to claim 1, wherein a plurality of the magnetoresistive elements are arranged corresponding to the magnets.   The magnet is provided for each magnetoresistive element, and when the magnetosensitive part is viewed in the moving direction of the object to be detected, the end of the magnetosensitive part of the adjacent magnetoresistive element is positioned at the end face of the magnet. The long magnetic sensor according to claim 1, wherein the long magnetic sensor is substantially coincident.   6. The long magnetic sensor according to claim 1, wherein a plurality of the magnets are provided, and a gap is provided between the end faces of the magnets adjacent to each other.

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