JP2016095138A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of reducing output variation due to variation in passing position of media.SOLUTION: A magnetic sensor 1 includes a permanent magnet 10 and spin-valve magnetoresistance effect elements MR1-MR4. For each channel, a pair of spin-valve magnetoresistance effect elements MR1, MR2 and a pair of spin-valve magnetoresistance effect elements MR3, MR4 are symmetrically arranged about the center of a channel width, with an empty region 13 located therebetween having no direction-detecting magnetoresistance effect elements for identifying a medium 30 disposed therein.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached, for example, a bill.

  ATMs, vending machines, and the like are provided with banknote identification devices that identify inserted banknotes. A banknote identification apparatus is provided with the magnetic sensor which reads the magnetic ink printed on the banknote. A magnetic sensor has a magnet and the magnetic detection element provided above the magnetic pole surface of the said magnet, for example, and detects the magnetic fluctuation accompanying the passage of a banknote. In Patent Document 1 below, a pair of spin-valve magnetoresistive elements are arranged substantially perpendicular to the relative movement direction of a medium to be identified, and the medium is moved relative to the pair of spin-valve magnetoresistive elements. A configuration for applying a bias magnetic field substantially perpendicular to the direction is disclosed.

JP 2006-266862 A

  For example, in the banknote identification device, when the inserted banknote is identified while being moved in the short direction, the longitudinal position of the banknote changes slightly each time it is inserted. If it does so, the position of the magnetic pattern of the bill which passes on a magnetic sensor will also change, and will affect the output of a magnetic sensor. In order to improve identification accuracy, it is desirable that such influence be as small as possible.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a magnetic sensor capable of reducing the output fluctuation due to the passage position fluctuation of the medium.

One embodiment of the present invention is a magnetic sensor. This magnetic sensor
A magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached,
A plurality of direction-sensing magnetoresistive elements arranged substantially perpendicular to the relative movement direction of the medium;
Magnetic field generating means for applying a bias magnetic field to the plurality of direction detection type magnetoresistive effect elements,
The plurality of direction detection type magnetoresistive effect elements have first and second direction detection type magnetoresistive effects that have a relationship in which when one of the plurality of direction detection type magnetoresistive effect elements is in a high resistance state, the other is in a low resistance state. Including element groups,
The direction detection type magnetoresistive effect element in the vicinity of the boundary on each of both sides with the center of the length range of the arrangement of the plurality of direction detection type magnetoresistive effect elements as compared with other than the vicinity of the boundary. Are sparsely arranged.

Another aspect of the present invention is a magnetic sensor. This magnetic sensor
A magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached,
A plurality of direction-sensing magnetoresistive elements arranged substantially perpendicular to the relative movement direction of the medium;
Magnetic field generating means for applying a bias magnetic field to the plurality of direction detection type magnetoresistive effect elements,
The plurality of direction detection type magnetoresistive effect elements have first and second direction detection type magnetoresistive effects that have a relationship in which when one of the plurality of direction detection type magnetoresistive effect elements is in a high resistance state, the other is in a low resistance state. Including element groups,
There is a non-arrangement area in which the direction identification type magnetoresistive element for medium identification is not arranged at the center of the length range of the arrangement of the plurality of direction detection type magnetoresistive elements.

Another aspect of the present invention is a magnetic sensor. This magnetic sensor
A magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached,
A plurality of direction-sensing magnetoresistive elements arranged substantially perpendicular to the relative movement direction of the medium;
Magnetic field generating means for applying a bias magnetic field to the plurality of direction detection type magnetoresistive effect elements,
The plurality of direction detection type magnetoresistive effect elements have first and second direction detection type magnetoresistive effects that have a relationship in which when one of the plurality of direction detection type magnetoresistive effect elements is in a high resistance state, the other is in a low resistance state. Including element groups,
The point-like magnetic pattern in the arrangement direction when the point-like magnetic pattern is relatively moved in the same direction as the relative movement direction of the medium and passed through the vicinity of the plurality of direction-sensitive magnetoresistive elements. The variation width of the output characteristics obtained from the plurality of direction detection type magnetoresistive effect elements with respect to the position is the length of the arrangement of the plurality of direction detection type magnetoresistive effect elements is the position of the dotted magnetic pattern with respect to the arrangement direction. With reference to the output when it coincides with the center of the range, it is within 10% in the continuous range of at least 60% including the center in the length range of the arrangement of the plurality of direction detecting magnetoresistive elements.

  The plurality of direction detection type magnetoresistive effect elements may be present in the same number on both sides with the center of the length range of the array as a boundary.

  The first and second direction-sensitive magnetoresistive element groups may be located on opposite sides of the boundary.

  The plurality of direction-sensitive magnetoresistive elements may be arranged symmetrically with respect to each other with the boundary therebetween.

  The plurality of direction detection type magnetoresistive effect elements are connected in series so that the first and second direction detection type magnetoresistive effect element groups are separated from each other on the high voltage side and the low voltage side, and the first and second The sensor output may be taken out from the interconnection point of the direction detection type magnetoresistive element group.

  Each of the plurality of direction detection type magnetoresistive effect elements may be a spin valve type magnetoresistive effect element.

  The plurality of direction detection type magnetoresistive effect elements may constitute one channel, further include at least one channel having the same structure, and the plurality of channels may be arranged substantially perpendicular to the relative movement direction of the medium.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the magnetic sensor which can make the output fluctuation | variation by the passage position fluctuation | variation of a medium small can be provided.

1 is a schematic perspective view of a magnetic sensor 1 according to an embodiment of the present invention. 1 is a simple circuit diagram of a magnetic sensor 1. FIG. FIG. 3 is a waveform diagram of the sensor output Vout shown in FIG. 2 when the medium 30 shown in FIG. 1 passes over the magnetic sensor 1. 1 is a plan view of a magnetic sensor 1 according to Embodiment 1. FIG. FIG. 3 is a longitudinal characteristic diagram of the magnetic sensor 1 in the first embodiment. FIG. 6 is a plan view of a magnetic sensor 2 according to a second embodiment. FIG. 10 is a longitudinal characteristic diagram of the magnetic sensor 2 in the second embodiment. The top view of the magnetic sensor which concerns on the comparative example 1. FIG. The longitudinal direction characteristic view of the magnetic sensor in the comparative example 1. The top view of the magnetic sensor which concerns on the comparative example 2. FIG. The longitudinal direction characteristic view of the magnetic sensor in the comparative example 2. FIG. 6 is a plan view of a magnetic sensor 3 according to a third embodiment. FIG. 10 is a longitudinal characteristic diagram of the magnetic sensor 3 in the third embodiment. FIG. 6 is a plan view of a magnetic sensor 4 according to a fourth embodiment. FIG. 10 is a longitudinal characteristic diagram of the magnetic sensor 4 in the fourth embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are examples, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  FIG. 1 is a schematic perspective view of a magnetic sensor 1 according to an embodiment of the present invention. In the figure, XYZ axes that are three orthogonal axes are defined. The magnetic sensor 1 identifies a medium 30 to which magnetic powder or a magnetic film is attached, and is incorporated in, for example, a bill identifying device. The medium 30 is substantially parallel to the XY plane, is transported in the X direction by a transport system (not shown), and passes above the magnetic sensor 1. The magnetic pattern 31 of the medium 30 shown in FIG. 1 is a simple example for illustration, and if the medium 30 is a banknote, a complicated magnetic pattern corresponding to the type of banknote is formed on the medium 30. .

  The magnetic sensor 1 includes a permanent magnet 10 as a magnetic field generating unit and spin valve magnetoresistive elements MR1 to MR4 as direction detecting magnetoresistive elements. In FIG. 1, the spin valve magnetoresistive elements MR1 to MR4 are drawn larger in relation to the size of the medium 30, but actually the spin valve magnetoresistive elements MR1 to MR4 are in relation to the medium 30. The dimensions are very small. The spin valve magnetoresistive elements MR1 to MR4 may be either spin valve giant magnetoresistive elements or spin valve tunnel magnetoresistive elements.

  The spin valve magnetoresistive elements MR1 to MR4 are provided above the N pole surface of the permanent magnet 10 substantially parallel to the XY plane. The magnetosensitive surfaces of the spin valve magnetoresistive elements MR1 to MR4 are substantially parallel to the XY plane. While the relative movement direction of the medium 30 is the X direction, the arrangement direction of the spin valve magnetoresistive elements MR1 to MR4 is the Y direction. The magnetic sensor 1 is a multi-channel type, and includes a set of spin valve magnetoresistive elements MR1 to MR4 constituting one channel for the number of channels. The channel arrangement direction is the Y direction. In other words, the magnetic sensor 1 includes a plurality of channels arranged in the Y direction, and each channel includes the spin valve magnetoresistive elements MR1 to MR4.

  In each channel, the spin valve magnetoresistive elements MR1 and MR2 constitute a first direction sensing magnetoresistive element group 11, and the spin valve magnetoresistive elements MR3 and MR4 comprise a second direction sensing magnetoresistive element. The effect element group 12 is configured. The first direction detection type magnetoresistive effect element group 11 and the second direction detection type magnetoresistive effect element group 12 have the center of the channel width (the length range of the arrangement of the spin valve type magnetoresistive effect elements MR1 to MR4). They are positioned on opposite sides as the boundary, and preferably arranged symmetrically with respect to the boundary. A non-arranged region in which no direction-detecting magnetoresistive element for identifying the medium 30 is disposed between the first direction-sensitive magnetoresistive element group 11 and the second direction-sensitive magnetoresistive element group 12 13 exists. However, when the number of spin-valve magnetoresistive elements per channel is increased, the non-arrangement region 13 may not be provided. Regardless of the presence / absence of the non-arrangement region 13, the spin valve magnetoresistive elements are arranged sparsely in the vicinity of the boundary on both sides of the boundary in each channel as compared with other than the vicinity of the boundary. Note that sparse is a concept including a case where the arrangement density is zero.

  In the spin valve magnetoresistive elements MR1 and MR2 constituting the first direction detection type magnetoresistive element group 11, the pinned layer magnetization direction is in the −X direction. In the spin valve magnetoresistive elements MR3 and MR4 constituting the second direction detection type magnetoresistive element group 12, the pinned layer magnetization direction is the + X direction. A spin valve magnetoresistive element is an element whose resistance value changes depending on the relationship between the magnetic field applied to itself (external magnetic field) and the pinned layer magnetization direction, and has low resistance when the external magnetic field has a pinned layer magnetization direction component. When the external magnetic field has an anti-pin layer magnetization direction component, the resistance is high.

式１において、Ｒ（ＭＲ１,ＭＲ２）は、スピンバルブ型磁気抵抗効果素子ＭＲ１,ＭＲ２の合成抵抗値であり、Ｒ（ＭＲ３,ＭＲ４）は、スピンバルブ型磁気抵抗効果素子ＭＲ３,ＭＲ４の合成抵抗値である。 FIG. 2 is a simple circuit diagram of the magnetic sensor 1. The spin valve magnetoresistive elements MR1 to MR4 constituting each channel are connected in series between the output terminal of the DC power supply E and the ground. In each channel, the sensor output Vout is taken out from the interconnection point of the spin valve magnetoresistive elements MR2 and MR3 (interconnection point of the first and second direction detection type magnetoresistive element groups 11 and 12). The sensor output Vout is expressed by the following formula 1.

In Equation 1, R (MR1, MR2) is a combined resistance value of the spin valve magnetoresistive elements MR1, MR2, and R (MR3, MR4) is a combined resistance of the spin valve magnetoresistive elements MR3, MR4. Value.

  FIG. 3 is a waveform diagram of the sensor output Vout shown in FIG. 2 when the medium 30 shown in FIG. 1 passes above the magnetic sensor 1. When the magnetic pattern 31 of the medium 30 is far from the magnetic sensor 1, the magnetic field generated by the permanent magnet 10 passes through the magnetic sensitive surfaces of the spin valve magnetoresistive effect elements MR 1 to MR 4 vertically without being affected by the magnetic pattern 31. Therefore, the spin valve magnetoresistive elements MR1 to MR4 are both in the middle resistance state and have the same resistance value, and the sensor output Vout does not vary at the intermediate value. Thereafter, when the medium 30 moves in the + X direction and the magnetic pattern 31 comes close to the upper front side (−X direction side) of the spin valve magnetoresistive elements MR1 to MR4, the magnetic field generated by the permanent magnet 10 is The spin valve magnetoresistive elements MR1 to MR4 are attracted in the -X direction on the magnetosensitive surfaces, the spin valve magnetoresistive elements MR1 and MR2 are in a low resistance state, and the spin valve magnetoresistive elements MR3 and MR4 are high. The resistance state is reached, and the sensor output Vout increases from the intermediate value. Thereafter, when the magnetic pattern 31 passes immediately above the spin valve magnetoresistive elements MR1 to MR4, the magnetic field generated by the permanent magnet 10 is + X from the −X direction on the magnetosensitive surface of the spin valve magnetoresistive elements MR1 to MR4. As a result, the spin valve magnetoresistive elements MR1 and MR2 enter a high resistance state, the spin valve magnetoresistive elements MR3 and MR4 enter a low resistance state, and the sensor output Vout decreases from an intermediate value. The above is repeated four times for the number of the magnetic patterns 31 here.

  The position in the Y direction of the medium 30 transported in the X direction changes slightly each time the medium 30 is loaded, and the position in the Y direction of the magnetic pattern 31 of the medium 30 passing over the magnetic sensor 1 also changes. When the magnetic pattern formed on the medium 30 is fine unlike the magnetic pattern 31 shown in FIG. 1, if the passing position of the fine magnetic pattern in the Y direction changes, the sensor output Vout of the magnetic sensor 1 is also affected. On the other hand, the magnetic strength of the magnetic pattern also affects the sensor output Vout. For this reason, if the sensor output Vout varies greatly depending on the Y-direction passing position of the magnetic pattern, whether the fluctuation of the sensor output Vout indicates the fluctuation of the Y-direction passing position of the magnetic pattern or the magnetic strength of the magnetic pattern. I don't know if it shows any change. Therefore, in order to improve the identification accuracy, it is desirable that the fluctuation of the sensor output Vout due to the fluctuation of the passing position of the magnetic pattern in the Y direction is as small as possible.

  From the above equation 1, the peak peak value (difference between the maximum value and the minimum value) of the sensor output Vout increases as the resistance change of the spin valve magnetoresistive elements MR1 to MR4 increases. The resistance change decreases as the passing position of the magnetic pattern moves away in the Y direction, and increases as it approaches. In the case of a configuration in which spin valve magnetoresistive elements are arranged sparsely on the both sides of the boundary in each channel as in the present embodiment, in the vicinity of the boundary, compared to other than the vicinity of the boundary, When the passing position is shifted left and right from the boundary, one of the first and second direction detection type magnetoresistive element groups 11 and 12 has a large resistance change, and the other has a small resistance change. The effects of resistance changes in both groups are preferably offset. Therefore, in this embodiment, even if the passing position of the magnetic pattern in the Y direction varies, the variation in the sensor output Vout can be reduced. Even when the spin valve magnetoresistive effect elements are spread within the channel width as in the comparative example described later (when the arrangement density is constant), the first and Although the second direction detection type magnetoresistive effect element groups 11 and 12 exhibit the resistance change having the same tendency as the embodiment, the influence of the resistance change of one group is related to the resistance change of the other group with respect to the sensor output Vout. If the influence cannot be completely offset and the passing position of the magnetic pattern in the Y direction fluctuates, the sensor output Vout fluctuates relatively greatly. Hereinafter, the effects of the present embodiment will be specifically described with reference to examples and comparative examples.

Example 1
FIG. 4 is a plan view of the magnetic sensor 1 according to the first embodiment. This example is an example in which four chips of spin valve type magnetoresistive effect elements are used in the same configuration as in FIG. In each of the first and second direction detection type magnetoresistive effect element groups 11 and 12, the adjacent spin valve type magnetoresistive effect elements are arranged close to each other so that there is almost no gap. The width of the non-arrangement region 13 was set to a width corresponding to approximately four spin valve magnetoresistive elements. The arrangement length (channel width) of the first and second direction detection type magnetoresistive element groups 11 and 12 was set to 5.2 mm.

  FIG. 5 is a longitudinal characteristic diagram of the magnetic sensor 1 according to the first embodiment. The longitudinal characteristic is a sensor with respect to the Y-direction passing position of the point-like magnetic pattern 32 when the point-like magnetic pattern 32 as shown in FIG. 4 is moved in the X-direction and passed over the magnetic sensor 1. This is a characteristic of the output Vout (peak peak value), and the same applies to Examples and Comparative Examples described later. The sensor output on the vertical axis is expressed as a percentage based on the case where the Y-direction passing position of the dotted magnetic pattern 32 is the center of the channel width (corresponding to the horizontal axis of 0 mm). As shown in FIG. 5, in the configuration of Example 1, the fluctuation range of the longitudinal characteristics is within 10% in total up and down in a continuous range of about 75% (about 4 mm in length) including the center in the channel width. Thus, a stable sensor output was obtained even when the Y-direction passing position of the dotted magnetic pattern fluctuated.

Example 2
FIG. 6 is a plan view of the magnetic sensor 2 according to the second embodiment. The present embodiment corresponds to one in which one spin valve magnetoresistive effect element is added to both ends of the channel of the first embodiment so that there is almost no gap. Each of the spin valve magnetoresistive effect elements constituting the first and second direction detection type magnetoresistive effect element groups 11 and 12 is 3 chips (the total of one channel is 6 chips). The width of the non-arrangement region 13 was the same as that in Example 1. The channel width was 6.4 mm.

  FIG. 7 is a characteristic diagram in the longitudinal direction of the magnetic sensor 2 in the second embodiment. In the configuration of Example 2, the fluctuation range of the longitudinal characteristics is within a total of 10% vertically in a continuous range of about 80% (about 5 mm in length) including the center in the channel width. Stable sensor output was obtained even when the passing position of the magnetic pattern in the Y direction fluctuated. Further, in comparison with Example 1, it was possible to widen the range in which stable sensor output can be obtained in the channel.

Comparative Example 1
FIG. 8 is a plan view of the magnetic sensor according to the first comparative example. The comparative example 1 is an example in which the non-arrangement region 13 is eliminated in the first embodiment, and the first and second direction detection type magnetoresistive effect element groups 11 and 12 are arranged so that there is almost no gap. The channel width was 2.8 mm.

  FIG. 9 is a longitudinal characteristic diagram of the magnetic sensor in the first comparative example. Also in the configuration of Comparative Example 1, the fluctuation range of the longitudinal characteristics was within 10% in total in the vertical direction in a continuous range of about 65% including the center in the channel width. However, the absolute length of the range in which the fluctuation range of the longitudinal characteristics is within 10% in total up and down is less than 2 mm, which is smaller than about 4 mm in Example 1. Thus, in the configuration of Comparative Example 1, it was not possible to sufficiently secure a range in which stable sensor output was obtained. In other words, in Example 1, the range in which a stable sensor output can be obtained can be expanded without increasing the number of spin-valve magnetoresistive elements per channel compared to Comparative Example 1. .

Comparative Example 2
FIG. 10 is a plan view of the magnetic sensor according to the second comparative example. In Comparative Example 2, each of the spin valve magnetoresistive effect elements constituting the first and second direction sensing type magnetoresistive effect element groups 11 and 12 is 7 chips (total of one channel is 14 chips). The non-arrangement region 13 was not provided in the same manner as in FIG. The channel width was 8.8 mm.

  FIG. 11 is a longitudinal characteristic diagram of the magnetic sensor in Comparative Example 2. In the configuration of Comparative Example 2, although the absolute length of the range in which the fluctuation range of the longitudinal characteristics is within 10% in total is 4 mm or more, the range is about 50% including the center in the channel width. Limited to a continuous range of This creates a large trough in the longitudinal direction between adjacent channels. In other words, even if there is no gap between adjacent channels, a range in which the sensor output Vout is greatly reduced exists as much as the width of one channel. As described above, in the configuration of Comparative Example 2, it was not possible to secure a sufficient range for obtaining a stable sensor output within the channel width. The range in which the fluctuation width of the longitudinal characteristics is within 10% in total up and down depends on the required specifications, but it is desirable to secure 60% or more including the center in the channel width.

Example 3
FIG. 12 is a plan view of the magnetic sensor 3 according to the third embodiment. In this embodiment, the spin valve type magnetoresistive effect elements constituting the first and second direction detection type magnetoresistive effect element groups 11 and 12 are each composed of 4 chips (total of 1 channel is 8 chips), and the boundary (channel Between the first and second spin-valve magnetoresistive elements from the center of the width, and between the third and fourth spin-valve magnetoresistive elements, approximately one spin valve A gap having a width corresponding to the type magnetoresistive effect element was provided. The width of the non-arrangement region 13 was set to a width corresponding to approximately two spin valve magnetoresistive elements. The channel width was 8.8 mm.

  FIG. 13 is a longitudinal characteristic diagram of the magnetic sensor 3 according to the third embodiment. In the configuration of Example 3, the fluctuation range of the longitudinal characteristics is within 10% in total in the vertical direction in a continuous range of about 65% (about 5.7 mm in length) including the center in the channel width, Stable sensor output was obtained even if the Y-direction passing position of the dotted magnetic pattern fluctuated. Further, in comparison example 2, while having the same channel width and an inexpensive configuration in which the number of spin-valve magnetoresistive effect elements per channel is reduced, the fluctuation width of the longitudinal characteristics is totaled vertically. The range within 10% could be expanded by 40% or more.

Example 4
FIG. 14 is a plan view of the magnetic sensor 4 according to the fourth embodiment. In this embodiment, the spin valve type magnetoresistive effect elements constituting the first and second direction sensing type magnetoresistive effect element groups 11 and 12 are each 5 chips (the total of one channel is 10 chips), and the boundary (channel Between the first and second spin-valve magnetoresistive elements from the center of the width) and between the second and third spin-valve magnetoresistive elements, approximately one spin valve A gap having a width corresponding to the type magnetoresistive effect element was provided. Further, the non-arrangement region 13 was not provided (the first and second direction detection type magnetoresistive effect element groups 11 and 12 were arranged so as to have almost no gap). The channel width was 8.8 mm.

  FIG. 15 is a longitudinal characteristic diagram of the magnetic sensor 4 according to the fourth embodiment. In the configuration of Example 4, the fluctuation range of the longitudinal characteristics is within 10% in total in the vertical direction in a continuous range of about 70% (length: about 6.1 mm) including the center in the channel width. Stable sensor output was obtained even if the Y-direction passing position of the magnetic pattern fluctuated. Further, in comparison example 2, while having the same channel width and an inexpensive configuration in which the number of spin-valve magnetoresistive effect elements per channel is reduced, the fluctuation width of the longitudinal characteristics is totaled vertically. The range within 10% could be expanded by 50% or more.

  According to the present embodiment, the following effects can be achieved.

(1) No direction detection type magnetoresistive effect element for identifying the medium 30 is disposed between the first direction detection type magnetoresistive effect element group 11 and the second direction detection type magnetoresistive effect element group 12. By providing the arrangement region 13 or the like, the spin valve magnetoresistive effect elements are arranged more sparsely in the vicinity of the boundary than in the vicinity of the boundary on both sides of the boundary in each channel. The fluctuation of the sensor output Vout due to the fluctuation of the passing position of the magnetic pattern of the medium 30 in the Y direction can be reduced.

(2) Since the spin valve magnetoresistive effect element per channel is increased as compared with the conventional one, the current consumption of the magnetic sensor 1 is reduced, and the power consumption can be reduced. Further, there is an advantage that the shot noise In expressed by the following formula 2 is reduced by reducing the current consumption.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  In the magnetic sensor 1, the number of spin-valve magnetoresistive elements per channel, the width of the non-arrangement region 13, the arrangement form of the spin-valve magnetoresistive elements in each channel, etc. are the specific examples shown in the embodiment. However, it can be arbitrarily set according to specifications such as the required number of channels and channel width. The magnetic sensor 1 is not limited to the multi-channel type, and may be a single-channel type.

  The plurality of spin-valve magnetoresistive elements constituting the first direction-sensitive magnetoresistive element group 11 may exist separately on both sides of the center of the channel width. The same applies to the plurality of spin-valve magnetoresistive elements that constitute the second direction detection type magnetoresistive element group 12. Further, the direction detection type magnetoresistive effect element may be a magnetoresistive effect element other than the spin valve type magnetoresistive effect element.

1 to 4 magnetic sensors, 10 permanent magnets, 11 first direction detection type magnetoresistive effect element group, 12 second direction detection type magnetoresistive effect element group, 13 non-arrangement region, 30 medium, 31 magnetic pattern, 32 points Magnetic pattern

Claims (9)

A magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached,
A plurality of direction-sensing magnetoresistive elements arranged substantially perpendicular to the relative movement direction of the medium;
Magnetic field generating means for applying a bias magnetic field to the plurality of direction detection type magnetoresistive effect elements,
The plurality of direction detection type magnetoresistive effect elements have first and second direction detection type magnetoresistive effects that have a relationship in which when one of the plurality of direction detection type magnetoresistive effect elements is in a high resistance state, the other is in a low resistance state. Including element groups,
The direction detection type magnetoresistive effect element in the vicinity of the boundary on each of both sides with the center of the length range of the arrangement of the plurality of direction detection type magnetoresistive effect elements as compared with other than the vicinity of the boundary. Magnetic sensors are arranged sparsely. A magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached,
A plurality of direction-sensing magnetoresistive elements arranged substantially perpendicular to the relative movement direction of the medium;
Magnetic field generating means for applying a bias magnetic field to the plurality of direction detection type magnetoresistive effect elements,
The plurality of direction detection type magnetoresistive effect elements have first and second direction detection type magnetoresistive effects that have a relationship in which when one of the plurality of direction detection type magnetoresistive effect elements is in a high resistance state, the other is in a low resistance state. Including element groups,
A magnetic sensor, wherein a non-arrangement region in which a direction identification type magnetoresistive effect element for identifying a medium is not present exists in the center of a length range of the arrangement of the plurality of direction detection type magnetoresistive effect elements. A magnetic sensor for identifying a medium to which magnetic powder or a magnetic film is attached,
A plurality of direction-sensing magnetoresistive elements arranged substantially perpendicular to the relative movement direction of the medium;
Magnetic field generating means for applying a bias magnetic field to the plurality of direction detection type magnetoresistive effect elements,
The plurality of direction detection type magnetoresistive effect elements have first and second direction detection type magnetoresistive effects that have a relationship in which when one of the plurality of direction detection type magnetoresistive effect elements is in a high resistance state, the other is in a low resistance state. Including element groups,
The point-like magnetic pattern in the arrangement direction when the point-like magnetic pattern is relatively moved in the same direction as the relative movement direction of the medium and passed through the vicinity of the plurality of direction-sensitive magnetoresistive elements. The variation width of the output characteristics obtained from the plurality of direction detection type magnetoresistive effect elements with respect to the position is the length of the arrangement of the plurality of direction detection type magnetoresistive effect elements is the position of the dotted magnetic pattern with respect to the arrangement direction. A magnetic field that is within 10% in a continuous range of at least 60% including the center of the length range of the array of the plurality of direction-sensitive magnetoresistive elements, with reference to the output at the same time as the center of the range. Sensor.   4. The magnetic sensor according to claim 1, wherein the plurality of direction detection type magnetoresistive elements are divided into the same number on both sides with the center of the length range of the array as a boundary. 5.   5. The magnetic sensor according to claim 4, wherein the first and second direction detection type magnetoresistive element groups are located on opposite sides of the boundary.   6. The magnetic sensor according to claim 4, wherein the plurality of direction detection type magnetoresistive elements are symmetrically arranged with respect to the boundary.   The plurality of direction detection type magnetoresistive effect elements are connected in series so that the first and second direction detection type magnetoresistive effect element groups are separated from each other on the high voltage side and the low voltage side, and the first and second The magnetic sensor as described in any one of Claim 1 to 6 from which a sensor output is taken out from the interconnection point of the direction detection type | mold magnetoresistive effect element group.   The magnetic sensor according to any one of claims 1 to 7, wherein each of the plurality of direction detection type magnetoresistive effect elements is a spin valve type magnetoresistive effect element.   The plurality of direction-sensitive magnetoresistive elements constitute one channel, and further include at least one channel having the same configuration, and the plurality of channels are arranged substantially perpendicular to the relative movement direction of the medium. The magnetic sensor according to any one of 1 to 8.

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