JP2005283477A - Magnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic sensor that easily ensures arrangement accuracy of a sensor chip to a bias magnet, and also stably obtains higher sensor sensitivity. <P>SOLUTION: The magnetic sensor 1 is constituted of a sensor chip 3 having a magnetoresistive element, and the bias magnet 2, having a rectangular groove in the longitudinal direction that, is formed to a substantially U-shape. Specially, the sensor chip 3 is disposed inclined to the bottom face of rectangular groove of the bias magnet 2, without forming a mold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic sensor that uses a magnetoresistive element (MRE) whose resistance value changes in accordance with a change in a magnetic field, and detects movement such as movement and rotation of a detection target made of a magnetic material.

  Magnetic sensors using magnetoresistive elements (MRE) are widely used to detect the motion of a detection target such as a rotor. In this type of magnetic sensor, a sensor chip including a magnetoresistive element is disposed between a detection target and a bias magnet that generates a bias magnetic field toward the detection target. The movement mode is detected. Moreover, as a magnetic sensor, the sensitivity is greatly influenced by the positional relationship between the magnetoresistive element and the bias magnet.

FIG. 9 shows an outline of an example in which such a magnetic sensor is applied to a rotation detection device (see, for example, Patent Document 1).
As shown in FIG. 9, the magnetic sensor 201 is disposed so as to face a rotor 208 having a large number of teeth 207 as a detection target. The magnetic sensor 201 includes a bias magnet 202 made of a permanent magnet and a sensor chip 204. The sensor chip 204 has a pair of magnetoresistive elements 203, and is molded with a resin integrally with a lead frame or the like by molding to constitute a mold IC 205. On the other hand, the bias magnet 202 has a cylindrical shape, and a through hole having a rectangular cross section is provided at the center thereof. The mold IC 205 is inserted into the through hole and fixed at a predetermined position. A sensor terminal (a power supply terminal and an output terminal) 206 that is a part of the lead frame is led out from an end portion (right end portion in the drawing) of the mold IC 205.

  FIG. 10 shows an example of the relationship between the distance (MM distance) between the magnetoresistive element 203 and the bias magnet 202 actually measured using the magnetic sensor 201 and the resistance change rate (sensitivity) of the magnetoresistive element 203. As shown.

As shown in FIG. 10, in such a magnetic sensor 201, the position of the magnetoresistive element 203 with respect to the bias magnet 202 greatly affects the rate of change in resistance. The resistance change rate is maximized at a position that fits inside.
Japanese Patent No. 312268

  Thus, by making the bias magnet 202 have a hollow structure and inserting the sensor chip 204 into the hollow portion, the sensitivity as the magnetic sensor 201 can be enhanced, and the magnetic sensor 201 itself can be made more compact.

However, in the configuration as described above, since the sensor chip 204 is molded, it is necessary to strictly manage the alignment accuracy of the sensor chip 204 at the time of molding.
Also, when the mold IC 205 is inserted into the hollow portion of the bias magnet 202 and the mold IC 205 and the bias magnet 202 are assembled, a sufficiently high assembly accuracy is required.

In addition, the sensor terminal 206 derived as described above needs to be connected to a dedicated connector, and this increase in the number of joints also leads to an increase in the risk in terms of reliability.
The present invention has been made in view of the above circumstances, and provides a magnetic sensor that can easily ensure the accuracy of disposition of a sensor chip with respect to a bias magnet and can stably obtain higher sensor sensitivity. The purpose is to do.

  In order to achieve such an object, the magnetic sensor according to claim 1 includes a sensor chip including a magnetoresistive element and a bias magnet that applies a bias magnetic field to the magnetoresistive element, and a magnetic substance to be detected moves. The sensor chip as a magnetic sensor for detecting a movement mode of a magnetic body as a detection target by sensing a change in magnetic vector generated in cooperation with the bias magnetic field as a change in resistance value of the magnetoresistive element Is configured to be fixed to the bias magnet in an inclined state.

  In order to obtain a stable output as a magnetic sensor using a magnetoresistive element whose resistance value changes in accordance with the change of the magnetic field, a saturated magnetic field is required. Usually, the magnetoresistive element is placed under the saturated magnetic field by the bias magnet. It is necessary to keep. If the sensor chip having such a magnetoresistive element is directly disposed on the bias magnet, it is possible to easily secure the accuracy of the sensor chip. However, when such a structure is adopted as a magnetic sensor, a change in the direction of magnetism that is approximately perpendicular to the sensor chip mounting surface of the bias magnet will be captured. When arranged on the top, it is difficult to sufficiently capture such a change in magnetic direction on the sensor chip. In this case, there is a region where the saturation magnetic field cannot be secured around the bias magnet. Therefore, in the present invention, as described above, when the sensor chip is fixed to the bias magnet, the sensor chip is fixed in an inclined state with respect to the bias magnet. As a result, even with respect to the change in the magnetic direction, the magnetoresistive element on the sensor chip can be suitably grasped, and it is preferable to improve the sensor chip placement accuracy and the sensor sensitivity with respect to the bias magnet. Can be achieved at the same time.

  Further, when the sensor chip is fixed while being tilted with respect to the bias magnet, the tilt angle can be set in accordance with the direction of the magnetic flux generated from the bias magnet as in the second aspect of the invention. More desirable. As a result, a saturation magnetic field as an operating environment of the magnetoresistive element can be easily secured, and a stable resistance change of the magnetoresistive element can be obtained in accordance with the change of magnetism.

Further, when the sensor chip is fixed in a state inclined with respect to the bias magnet, as a fixing method thereof, for example, as in the invention according to claim 3,
(A) A nonmagnetic member having an inclined surface is provided on a part of the magnet surface of the bias magnet, and the sensor chip is fixed to the inclined surface of the nonmagnetic member.
Or like invention of Claim 4,
(B) A housing having an inclined surface with respect to the magnet surface of the bias magnet is provided, and the sensor chip is fixed to the inclined surface of the housing.
Such a method is effective and easy to implement.

According to a fifth aspect of the present invention, in the configuration of the first aspect of the present invention, the bias magnet includes a signal transmission terminal.
With such a configuration, the use of the dedicated connector described above can be omitted.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect of the present invention, the signal transmission terminal is formed by insert molding on the bias magnet.
With such a configuration, a signal transmission terminal can be easily formed.

  Further, in the configuration of the invention according to claim 5 or 6, as in the invention according to claim 7, the sensor chip is configured to be connected to the signal transmission terminal. The risk in terms of reliability related to secure connections is also greatly reduced.

  Furthermore, in the configuration of the invention according to any one of claims 5 to 7, a configuration in which, for example, an electronic component such as a capacitor is connected between the signal transmission terminals as in the invention according to claim 8. It can also be. As a result, not only the electrical characteristics but also the space can be improved.

  In the invention according to claim 9, in the configuration of the invention according to any one of claims 1 to 8, the bias magnet has a substantially U-shaped cross section in which a rectangular groove is provided in a length direction. The sensor chip is formed and fixed to the bottom surface of the groove of the bias magnet.

  According to such a configuration, the bias magnet is formed in a substantially U-shaped cross section in which a rectangular groove is provided in the length direction, and the sensor chip is disposed on the bottom surface of the groove. For this reason, the sensor chip can be easily arranged, and further improvement in sensitivity as the sensor can be expected.

  Further, the configuration of the invention according to any one of claims 1 to 9 is a rotor in which the magnetic body to be detected is provided on an appropriate rotation shaft as in the invention according to claim 10. The magnetic sensor detects a change in the magnetic vector that occurs in cooperation with the bias magnetic field as the rotor rotates in the vicinity of the sensor chip as a change in the resistance value of the magnetoresistive element, and It is particularly effective to configure it as a rotation sensor that detects the rotation mode.

(First embodiment)
Hereinafter, a first embodiment in which a magnetic sensor according to the present invention is applied to a rotation sensor (rotation detection device) will be described with reference to FIGS.

  FIG. 1 is a perspective view schematically showing a perspective structure of the magnetic sensor according to the present embodiment. As shown in FIG. 1, the magnetic sensor is inclined to a bias magnet 2 having a rectangular groove in the length direction and having a substantially U-shaped cross section, and a bottom surface 21 of the rectangular groove of the bias magnet 2. The sensor chip 3 is provided. A bias magnetic field is emitted from the bias magnet 2 toward a detection target (not shown) such as a rotor made of a magnetic material via the sensor chip 3, and a magnetic vector that changes according to the rotational motion of the rotor or the like. Is detected by the sensor chip. In addition, this sensor chip 3 is also provided with the magnetoresistive element mentioned above.

  FIGS. 2A, 2B, and 2C show a planar structure, a front structure, and a schematic side structure partially seen through the magnetic sensor, respectively. As shown in these drawings, particularly FIG. 2 (c), in the magnetic sensor, the sensor chip 3 is disposed along the direction of the magnetic vector H emitted from the bias magnet 2. Further, a combined vector of the magnetic vectors H when the sensor chip 3 is arranged in this way is as shown in FIG. That is, as shown in FIG. 2 (d), the sensor chip 3 is arranged so as to be substantially along the direction of the magnetic vector at the arrangement location, so that most of the magnetic vector H is parallel to the sensor chip 3. Therefore, the presence of a region where a saturation magnetic field cannot be secured is avoided. In other words, such a magnetic vector H (Hxyz) is used to the maximum for forming a saturated magnetic field, and a change in the magnetic vector can be detected more easily through the sensor chip.

  Note that if the sensor chip 3 is arranged in an inclined state with respect to the bottom surface 21 of the rectangular groove of the bias magnet 2 even if it does not completely coincide with the direction of the magnetic vector H, the sensor chip 3 depends on the inclination angle. Thus, the magnetic vector component Hxyz parallel to the plane of the sensor chip 3 tends to increase. The increased magnetic vector component Hxyz makes it easy to secure a saturation magnetic field as an operating environment of the magnetoresistive element provided in the sensor chip 3.

  As described above, by arranging the sensor chip 3 in the state of being inclined to the bias magnet, a saturation magnetic field can be easily secured. Disappear.

  Next, a more specific configuration of the magnetic sensor of the present embodiment will be described in detail with reference to FIG. In FIG. 3, FIG. 3A shows the planar structure of the magnetic sensor, and FIGS. 3B and 3C show the BB ′ sectional structure and C- C ′ shows a cross-sectional structure.

  As shown in FIG. 3, the sensor chip 3 includes two pairs of magnetoresistive elements (MRE) 31, 32, 33, and 34 formed in an H shape on an insulating substrate, for example. These magnetoresistive elements 31 to 34 detect a change in the magnetic vector of the bias magnetic field generated from the bias magnet 2 as a change in resistance value, and detect a movement mode such as rotation of the rotor that is a detection target.

  Here, the two pairs of magnetoresistive elements 31, 32 and 33, 34 constituting the sensor chip 3 are arranged symmetrically with respect to the central axis (magnetic center of the bias magnetic field) of the bias magnet 2. The magnetoresistive elements 31 to 34 are patterned so as to form an angle of approximately 45 degrees or −45 degrees with the central axis of the bias magnet 2. Thereby, the waveform crack of the output from the magnetoresistive elements 31-34 is prevented effectively. The sensor chip 3 is configured using the two pairs of magnetoresistive elements 31, 32, 33, and 34, so that a differential operation can be performed. A resistance element may be provided.

  As shown in FIG. 3, a support base 7 made of a nonmagnetic member such as resin is fixed to a part of the bottom surface 21 of the rectangular groove serving as the magnet surface of the bias magnet 2 with an adhesive or the like. The support base 7 includes an inclined surface that forms a predetermined angle with respect to the bottom surface 21 of the bias magnet 2, and a recess 8 is formed on the inclined surface. The sensor chip 3 is disposed and fixed in the recess 8 by bonding with an adhesive or the like. Thus, the sensor chip 3 is disposed at a predetermined angle with respect to the bottom surface 21 of the bias magnet 2. In addition, this arrangement | positioning angle, ie, the inclination angle of the support stand 7, is set so that the direction of the magnetic vector in the arrangement | positioning position of the sensor chip 3 estimated by the magnetic simulation may be followed.

  Further, as shown in FIG. 3, terminals 4a, 4b and 4c are insert-molded on the bottom surface 21 of the rectangular groove of the bias magnet 2. And these terminals 4a-4c are electrically connected with the electrode of the sensor chip 3 by wire bonding. A protective capacitor 6a is electrically connected and fixed between the terminals 4a and 4b, and a protective capacitor 6b is electrically connected and fixed between the terminals 4b and 4c.

  In this embodiment, as described above, the sensor chip 3 is not directly molded, but is directly disposed on the bottom surface 21 of the bias magnet 2 having a substantially U-shaped cross section. This facilitates the placement of the sensor chip 3 and greatly improves the positional accuracy.

  Hereinafter, for the sake of convenience, based on data when the sensor chip 3 is arranged in parallel to the bottom surface 21 of the bias magnet 2, how the sensitivity as the magnetic sensor is improved by improving the arrangement accuracy of the sensor chip 3. Explain how it can be improved.

First, how the accuracy of the arrangement position of the sensor chip 3 affects the sensitivity of the magnetic sensor will be described based on the result of magnetic simulation.
FIG. 4 is a diagram showing the relationship between the rotor rotation angle and the sensor sensitivity of the magnetic sensor, using the relative displacement in the left-right direction between the sensor chip 3 and the bias magnet 2 as a parameter. In FIG. 4, the sensor sensitivity on the vertical axis is expressed in correspondence with the magnetic deflection angle emitted from the bias magnet 2. Here, the sensor sensitivity “0.0” corresponds to the threshold value of the magnetic deflection angle. As shown in FIG. 4, the sensor chip 3 is disposed in the left-right direction with reference to the center axis (magnetic center of the bias magnet 2) of the two pairs of magnetoresistive elements disposed on the left and right. Also, the deviation of the rotor rotation angle becomes large. For example, when the distance between the rotor and the sensor is “0.5 mm”, if the sensor chip 3 is displaced by “0.05 mm” in the left-right direction with respect to the center position, the deviation of the rotation angle of the rotor is about “0. When the angle is 2 ”and“ 0.1 mm ”is deviated in the left-right direction, the deviation of the rotational angle of the rotor is about“ 0.4 ”.

  FIG. 5 is a diagram showing the relationship between the rotor rotation angle and the sensor sensitivity of the magnetic sensor using the relative positional deviation between the sensor chip 3 and the bias magnet 2 in the front-rear direction (the magnetic direction of the bias magnet 2) as a parameter. is there. As shown in FIG. 5, the rotational angle deviation of the rotor increases as the position of the sensor chip 3 is shifted in the front-rear direction with reference to the midpoint in the front-rear direction of the two pairs of magnetoresistive elements. This point is the same as the tendency shown in FIG. For example, when the distance between the rotor sensors is “1.5 mm” and the sensor chip 3 is displaced by “0.05 mm” with respect to the reference position, the deviation of the rotation angle of the rotor is about “0.38” degrees. When the deviation is “0.1 mm”, the deviation of the rotation angle of the rotor is about “0.75” degrees.

  In this way, whether the sensor chip 3 is disposed in the left-right direction or the front-rear direction, the deviation of the rotation angle of the rotor increases as the deviation increases. That is, the arrangement accuracy of the sensor chip 3 has a great influence on the sensitivity of the magnetic sensor.

  FIG. 6 shows the result of measuring the mounting accuracy in the left-right direction and the front-rear direction for a prototype in which the sensor chip 3 is directly disposed on the bias magnet 2. In FIG. 6, the horizontal axis represents the displacement of the sensor chip 3 placement position (chip mount position displacement in the figure), and the vertical axis represents the frequency of occurrence of each displacement amount. In addition, a white bar graph indicates a positional shift in the left-right direction, and a hatched bar graph indicates a positional shift in the front-rear direction. As a result of the actual measurement, the average value of the deviation in the left-right direction is “−2.26 μm”, and the 3σ (standard deviation) value is “46.5 μm”. The average value of the deviation in the front-rear direction is “14.5 μm”, and the 3σ value is “40.5 μm”. Here, assuming that the distribution of the deviation amounts in the left-right direction and the front-rear direction follows a normal distribution, the probability that the deviation amounts in the left-right direction and the front-rear direction are within the range of “-50 μm to 50 μm” is “99.97%. It may be considered that there is no deviation amount exceeding this range in practical use.

  In this way, by directly disposing the sensor chip 3 on the bottom surface 21 of the bias magnet 2 having a substantially U-shaped cross section, the accuracy of the disposition position is within “0.05 mm (50 μm)”. Compared with the arrangement accuracy in the conventional structure (at least “0.15 mm” in the left and right and front and rear directions), the position accuracy is remarkably improved.

  Further, as described above, since the sensor chip 3 is not molded, but directly disposed on the bottom surface 21 of the bias magnet 2, the distance between the magnetoresistive element and the side wall of the bias magnet is set to about “1 mm”. It can also be approached.

  Incidentally, in the past, since the sensor chip was once formed in an IC mold and this IC mold was placed on the bias magnet, the distance between the magnetoresistive element and the side wall of the bias magnet was at least “2 mm” or more. On the other hand, in the present embodiment, since the sensor chip 3 is not molded, the distance between the centers of the two pairs of magnetoresistive elements 31, 32, 33, and 34 and the side wall of the bias magnet 2 can be further shortened. it can. This also improves the sensor sensitivity of the magnetic sensor.

  FIG. 7 shows the relationship between the distance L from the center of the magnetoresistive element pair to the side wall of the bias magnet 2 and the sensor sensitivity. As shown in FIG. 7, by reducing the distance between the center of the magnetoresistive element pair and the side wall of the bias magnet 2 from “2 mm” to “1 mm”, the sensor sensitivity can be greatly increased.

As described above, according to the present embodiment, the following effects can be obtained.
(1) In the present embodiment, the sensor chip 3 is disposed in a state inclined to the bias magnet 2. For this reason, a saturation magnetic field necessary for stable operation of the magnetoresistive elements 31 to 34 can be easily secured, and a change in the magnetic vector can be detected more accurately. In particular, if the sensor chip is arranged along the direction of the magnetic vector estimated by a magnetic simulation or the like, the effect becomes more remarkable.

  (2) Further, in order to install the sensor chip 3 in a state inclined to the bias magnet 2, a support base 7 is provided in the rectangular groove portion of the bias magnet 2, and the sensor chip 3 is disposed on the inclined surface of the support base 7. I did it. For this reason, the sensor chip 3 can be stably disposed without increasing the overall size of the magnetic sensor.

  (3) Since the bias magnet 2 having a substantially U-shaped cross section is used, the sensor chip 3 can be easily disposed, and the disposition accuracy is preferably improved. As a result, the sensitivity as a magnetic sensor is also preferably increased.

  (4) Since the sensor chip 3 is disposed on the bottom surface 21 of the rectangular groove of the bias magnet 2 without being molded, there is no need to manage alignment accuracy as in the case of molding, and the sensor The placement accuracy of the chip 3 can be easily ensured. In addition, since the distance between the magnetic sensor element and the side wall of the bias magnet 2 can be shortened, the sensor sensitivity of the magnetic sensor is further improved.

  (5) Moreover, the bias magnet 2 is provided with signal transmission terminals 4a to 4c by insert molding. This eliminates the need for a dedicated connector for taking out signals to the outside. Further, since the sensor chip 3 is directly connected to the signal transmission terminals 4a to 4c, the number of joints is reduced and the electrical reliability is further improved.

  In the above embodiment, the support 7 is made of resin, but may be any non-magnetic material, and other materials such as copper, aluminum, stainless steel, or wood may be used as appropriate. It can be adopted.

In the above embodiment, the concave portion 8 is provided on the inclined surface of the support base 7. However, the sensor chip 3 may be directly disposed on the inclined surface of the support base 7 without providing the concave portion 8. Good.
In the above embodiment, the support 7 is provided with an inclined surface and the entire sensor chip 3 is disposed on the inclined surface. However, if the sensor chip 3 can be stably disposed, for example, The support base 7 may be formed so as to support a part of the sensor chip 3 by placing one end of the sensor chip 3 directly on the bottom surface 21 of the bias magnet 2.

(Second Embodiment)
Hereinafter, a second embodiment of the magnetic sensor according to the present invention will be described with reference to FIG. In the present embodiment, in place of the support base 7 that supports the sensor chip 3 in the first embodiment, the sensor chip 3 is arranged using a part of the housing provided in the bias magnet 2. The structure is set up. The other points are the same as those of the magnetic sensor according to the first embodiment. In FIG. 8, the same elements are denoted by the same reference numerals, and overlapping descriptions are given. Will be omitted.

  FIG. 8 shows a side sectional structure corresponding to FIG. 3B of the magnetic sensor according to the present embodiment. As described above, the magnetic sensor is composed of a plurality of components such as the bias magnet 2, the sensor chip 3, the protective capacitors 6a and 6b, and bonding wires. In order to integrate these components and to protect the magnetic sensor from an external force or the like, in this embodiment, a housing 9 made of resin or the like is provided in the form shown in FIG. .

  Here, the housing 9 is provided with a protruding portion 9 a so as to enter the rectangular groove of the bias magnet 2. The projecting portion 9a is formed with an inclined surface having a predetermined angle with the bottom surface 21 of the bias magnet 2, and the sensor chip 3 is fixed to the inclined surface with an adhesive or the like. As a result, the sensor chip 3 is also arranged in an inclined state with respect to the bottom surface 21 of the bias magnet 2. In addition, this arrangement | positioning angle, ie, the inclination angle of the said protrusion part 9a, is also set so that the direction of the magnetic vector in the arrangement | positioning position of the sensor chip 3 estimated by the magnetic simulation may be followed.

Also by the magnetic sensor according to the present embodiment described above, effects equivalent to or equivalent to the effects (1) to (5) of the first embodiment can be obtained.
In the above embodiment, the sensor chip 3 is directly disposed on the inclined surface of the projecting portion 9a. However, a concave portion is provided on the inclined surface, and the sensor chip 3 is disposed on the concave portion. Good.

(Other embodiments)
In addition, the following elements can be changed in common with the above embodiments.
In each of the above embodiments, the bias magnet 2 is formed to have a substantially U-shaped cross section. However, the shape of the bias magnet 2 is not limited to this, and any other magnetic material that can generate a magnetic field may be used. You may form in this shape.

  In each of the above embodiments, the inclination angle of the inclined surface of the support base 7 or the overhang portion 9a on which the sensor chip is disposed is set so as to follow the direction of the magnetic vector. It is not necessary that the angle of inclination of the surface strictly follows the direction of the magnetic vector. Even when the inclination angle is deviated from the direction of the magnetic vector, the saturation magnetic field for the magnetoresistive elements 31 to 34 can be more easily compared with the case where the sensor chip 3 is disposed in parallel to the bottom surface 21 of the bias magnet 2. Therefore, the sensitivity can be improved more easily.

  In each of the above embodiments, the rotation mode of a detection target such as a rotor is detected using a magnetic sensor as a rotation sensor. However, the present invention is not limited to this, and is used for detection of a motion mode of an arbitrary detection target made of a magnetic material. Even it is effective.

The perspective view which shows the outline | summary of the perspective structure about 1st Embodiment of the magnetic sensor concerning this invention. About the magnetic sensor of the embodiment, (a) is a plan view showing the planar structure, (b) is a front view showing the front structure, and (c) is a side view showing a schematic side structure partially seen through. (D) The schematic which shows the synthetic | combination vector of the magnetic vector which acts on the sensor chip. (A) is a top view which shows the planar structure of the magnetic sensor of the embodiment in more detail. (B) is sectional drawing which shows the cross-section along the BB 'line of (a). (C) is sectional drawing which shows the cross-sectional structure along CC 'line of (a). The magnetic sensor of the embodiment WHEREIN: The graph which mainly shows the relationship between the position shift of the left-right direction of a sensor chip, and the shift | offset | difference of a rotor rotation angle. The magnetic sensor of the embodiment WHEREIN: The graph which mainly shows the relationship between the position shift of the front-back direction of a sensor chip, and the shift | offset | difference of a rotor rotation angle. The magnetic sensor of the embodiment WHEREIN: The graph which compares and shows the mounting precision of a sensor chip. The magnetic sensor of the embodiment WHEREIN: The graph which mainly shows the relationship between the distance between a sensor chip and the side wall of a bias magnet, and sensor sensitivity. Sectional drawing which shows the side surface cross-section about 2nd Embodiment of the magnetic sensor concerning this invention. (A) is a top view which shows the planar structure of the conventional magnetic sensor. (B) is a side view showing a side structure of a conventional magnetic sensor. The graph which shows the relationship between the distance (MM distance) between a magnetoresistive element and a bias magnet, and the resistance change rate of a magnetoresistive element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Magnetic sensor, 2 ... Bias magnet, 3 ... Sensor chip, 4a, 4b, 4c ... Signal transmission terminal, 5, 8 ... Recessed part, 6a, 6b ... Capacitor as an electronic component, 7 ... Support stand, 9 ... Housing , 9a ... overhang, 31, 32, 33, 34 ... magnetoresistive elements.

Claims (10)

A sensor chip having a magnetoresistive element and a bias magnet for applying a bias magnetic field to the magnetoresistive element, and a magnetic vector change caused in cooperation with the bias magnetic field when a magnetic body to be detected moves. In the magnetic sensor for detecting the movement mode of the magnetic body to be detected by sensing the change in the resistance value of the magnetoresistive element,
The sensor chip is fixed to the bias magnet in an inclined state. The magnetic sensor according to claim 1, wherein an inclination angle of the sensor chip is set to an angle corresponding to a direction of magnetic flux emitted from the bias magnet. The magnetic sensor according to claim 1, wherein the bias magnet includes a nonmagnetic member having an inclined surface on a part of the magnet surface, and the sensor chip is fixed to the inclined surface of the nonmagnetic member. The magnetic sensor according to claim 1, wherein the bias magnet includes a housing disposed with an inclined surface with respect to the magnet surface, and the sensor chip is fixed to the inclined surface of the housing. The magnetic sensor according to claim 1, wherein the bias magnet includes a signal transmission terminal. The magnetic sensor according to claim 5, wherein the signal transmission terminal is insert-molded in the bias magnet. The magnetic sensor according to claim 5, wherein the sensor chip is connected to the signal transmission terminal. The magnetic sensor according to any one of claims 5 to 7, wherein an electronic component is connected and disposed between the signal transmission terminals. The bias magnet is formed in a substantially U-shaped cross section in which a rectangular groove is provided in a length direction, and the sensor chip is fixed to a groove bottom surface of the bias magnet. The magnetic sensor according to one item. The magnetic object to be detected is a rotor provided on an appropriate rotation shaft, and the magnetic sensor has a magnetic vector generated in cooperation with the bias magnetic field when the rotor rotates in the vicinity of the sensor chip. The magnetic sensor according to any one of claims 1 to 9, wherein a change is sensed as a change in a resistance value of the magnetoresistive element to detect a rotation mode of the rotor.

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