JP2013044641A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor that can suppress fluctuation of an operating point and variations in resistance value ratios and in which temperature characteristics are improved.SOLUTION: A magnetic sensor 1 comprises a sensor circuit unit 2. The sensor circuit unit 2 includes a first series circuit 6 where first and third magnetic resistance elements R1, R3 are connected in series and a second series circuit 7 where second and fourth magnetic resistance elements R2, R4 are connected in series, and is constituted by a bridge circuit 5 where the first series circuit 6 and the second series circuit 7 are connected in parallel. Surfaces of the first through fourth magnetic resistance elements R1-R4 are covered with an insulator film 12. Further, the surfaces of the third magnetic resistance element R3 and the fourth magnetic resistance element R4 are formed with a magnetic flux magnetism collecting film 13 made of a magnetic material, with the insulator film 12 sandwiched therebetween.

Description

  The present invention relates to a magnetic sensor that detects a magnetic field using a magnetoresistive element.

  In general, a magnetic sensor in which a bridge circuit is configured by four first to fourth magnetoresistive elements is known (see, for example, Patent Document 1). When the magnetic field strength in the first direction is increased, the resistance values of the first and second magnetoresistive elements tend to decrease, and the resistance values of the third and fourth magnetoresistive elements remain unchanged. is there. On the other hand, when the magnetic field strength in the direction perpendicular to the first direction is increased, the resistance values of the third and fourth magnetoresistive elements tend to decrease. The resistance value is unchanged. The first magnetoresistive element and the third magnetoresistive element are connected in series via the first connection point to form a first series circuit, and the second magnetoresistive element, the fourth magnetoresistive element, Are connected in series via the second connection point to form a second series circuit. Furthermore, the first magnetoresistive element side of the first series circuit and the fourth magnetoresistive element side of the second series circuit are commonly connected via a third connection point, and the first series circuit The third magnetoresistive element side and the second magnetoresistive element side of the second series circuit are commonly connected via a fourth connection point, and are connected via the third connection point and the fourth connection point. A power supply voltage is applied, and an output voltage accompanying a magnetic field change is taken out via the first connection point and the second connection point. In general, the four first to fourth magnetoresistive elements are formed in substantially the same shape using the same material so as to have the same temperature characteristics.

JP 7-297463 A

  By the way, when a magnetic field tilted from the first direction to the second direction acts on the magnetic sensor, the resistance values of the first and second magnetoresistive elements are changed by the component of the magnetic field in the first direction. Thus, the resistance values of the third and fourth magnetoresistive elements also change depending on the component of the magnetic field in the second direction. As a result, for example, when the magnetic field strength at which the potential of the first connection point and the potential of the second connection point are reversed is set as the operating point of the magnetic sensor, this operating point is the direction of the magnetic field applied to the magnetic sensor. It changes according to. Specifically, when the inclination angle of the magnetic field applied to the magnetic sensor is sequentially changed from the first direction toward the second direction, the third and fourth magnetoresistive elements increase as the inclination angle increases. Since the change in resistance value becomes large, there is a problem that the fluctuation of the operating point of the magnetic sensor also becomes large.

  In consideration of such problems, the magnetic sensor of Patent Document 1 reduces the magnetoresistive effect by narrowing the pattern line width of the third and fourth magnetoresistive elements, and the third and fourth magnetic sensors. The sensitivity of the resistance element is reduced. However, since the pattern line width is different between the first and second magnetoresistive elements and the third and fourth magnetoresistive elements, the degree of influence of processing variations when forming the magnetoresistive elements is different. As a result, a large variation occurs in the resistance value ratio between the first and second magnetoresistive elements and the resistance value ratio between the third and fourth magnetoresistive elements. There is a problem that characteristic variations tend to occur. Further, as a result of different pattern line widths and thicknesses of the first to fourth magnetoresistive elements, there is a problem that the temperature coefficient of each magnetoresistive element varies and the temperature characteristics are not constant.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a magnetic sensor that can suppress variation in operating point and variation in resistance value ratio, and that has improved temperature characteristics. is there.

  In order to solve the above problem, the invention of claim 1 is characterized in that the first and second magnetoresistive elements whose resistance values change to the maximum when a detection magnetic field in the first direction is applied, and the third and fourth A first series circuit comprising a magnetoresistive element, wherein the first magnetoresistive element and the third magnetoresistive element are connected in series via a first connection point; and the second magnetism A second series circuit formed by connecting a resistance element and the fourth magnetoresistive element in series via a second connection point; a first magnetoresistive element side of the first series circuit; and The fourth series resistance side of the second series circuit is commonly connected via a third connection point, and the third series resistance side of the first series circuit and the second series are connected. The second magnetoresistive element side of the circuit is connected in common through a fourth connection point, and the third connection point and the circuit In the magnetic sensor for applying the power supply voltage through the four connection points and extracting the output voltage accompanying the magnetic field change through the first connection point and the second connection point, the third and fourth magnets Magnetic flux collecting means is provided on the surface of the resistance element, and when a magnetic field in a direction different from the detection magnetic field in the first direction is applied, the magnetic field applied to the third and fourth magnetoresistance elements is changed to the magnetic flux. The magnetic flux collecting means collects the magnetic flux and the change in the resistance value of the third and fourth magnetoresistive elements is reduced.

  The invention of claim 2 has first and second magnetoresistive elements whose resistance values change to the maximum when a detection magnetic field in the first direction is applied, and third and fourth magnetoresistive elements, A first series circuit formed by connecting the first magnetoresistive element and the third magnetoresistive element in series via a first connection point; the second magnetoresistive element; and the fourth magnetism. A second series circuit formed by connecting a resistive element in series via a second connection point, the first magnetoresistive element side of the first series circuit, and the second series circuit of the second series circuit; 4 and the second magnetoresistance element side of the first series circuit and the second magnetoresistance element of the second series circuit are connected in common through a third connection point. The element side is connected in common through the fourth connection point, and the power source power is supplied through the third connection point and the fourth connection point. And a first magnetic flux on the surfaces of the first and second magnetoresistive elements in a magnetic sensor that extracts an output voltage accompanying a magnetic field change through the first connection point and the second connection point. A magnetic flux collecting means is provided, and a second magnetic flux collecting means having a larger permeability than the first magnetic flux collecting means is provided on the surfaces of the third and fourth magnetoresistive elements. The magnetic field applied to the first and second magnetoresistive elements when a magnetic field in a direction different from the detected magnetic field is applied, compared to the amount of magnetic flux collected by the first magnetic flux collecting means. The amount of the magnetic field applied to the third and fourth magnetoresistive elements is increased by the second magnetic flux collecting means, and compared with the change in the resistance value of the first and second magnetoresistive elements. Reduced changes in the resistance values of the third and fourth magnetoresistive elements It is characterized in.

  According to a third aspect of the present invention, a yoke is provided on the third and fourth connection point sides so as to sandwich the first series circuit and the second series circuit.

  In the first aspect of the present invention, since the magnetic flux collecting means is provided on the surfaces of the third and fourth magnetoresistive elements, when a magnetic field in a direction different from the detected magnetic field in the first direction is applied, The magnetic field applied to the four magnetoresistive elements can be collected by the magnetic flux collecting means, and the change in the resistance values of the third and fourth magnetoresistive elements can be reduced. For this reason, even when the magnetic field acts with an inclination from the first direction, the change in the resistance value of the third and fourth magnetoresistive elements can be reduced, and the fluctuation of the operating point of the magnetic sensor can be suppressed. Can do.

  The first to fourth magnetoresistive elements can all be formed with the same pattern line width and thickness. For this reason, even when processing variations occur when forming the magnetoresistive element, the resistance value ratio hardly changes between the first and second magnetoresistive elements and the third and fourth magnetoresistive elements. The variation in resistance value ratio can be suppressed. Further, by arranging the pattern line width and thickness of the first to fourth magnetoresistive elements and the film forming materials, the temperature resistance coefficients of the first to fourth magnetoresistive elements are made substantially constant. Can do. Further, although the current flows in the vicinity of the surface of each magnetoresistive element due to the skin effect, the pattern line widths and thicknesses of the first to fourth magnetoresistive elements are made uniform, thereby affecting each magnetoresistive element. The effect of the skin effect is almost constant. As a result, it is possible to reduce variations in temperature coefficients related to the first to fourth magnetoresistive elements constituting the magnetic sensor.

  In the invention of claim 2, the first magnetic flux collecting means is provided on the surfaces of the first and second magnetoresistive elements, and the first magnetic flux collecting means is provided on the surfaces of the third and fourth magnetoresistive elements. Also, the second magnetic flux collecting means having a high magnetic permeability is provided. For this reason, when a magnetic field in a direction different from the detection magnetic field in the first direction is applied, the amount by which the magnetic field applied to the first and second magnetoresistive elements is collected by the first magnetic flux collecting means The amount of magnetic field applied to the third and fourth magnetoresistive elements is increased by the second magnetic flux collecting means, and the resistance values of the first and second magnetoresistive elements are increased. Compared with the change, the change in the resistance value of the third and fourth magnetoresistance elements can be reduced. For this reason, even when the magnetic field acts with an inclination from the first direction, the change in the resistance value of the third and fourth magnetoresistive elements can be reduced, and the fluctuation of the operating point of the magnetic sensor can be suppressed. Can do.

  In addition, since all of the first to fourth magnetoresistive elements can be formed with the same pattern line width and thickness, variation of the resistance value ratio can be suppressed as in the first aspect of the invention, and In addition, it is possible to reduce variations in temperature coefficients related to the first to fourth magnetoresistive elements constituting the magnetic sensor.

  In the invention of claim 3, since the yoke is provided on the third and fourth connection point sides so as to sandwich the first series circuit and the second series circuit, the yokes are arranged along the first direction. A magnetic field can be formed. For this reason, since the magnetic field of a 2nd direction can be reduced, the fluctuation | variation of the operating point of a magnetic sensor and the dispersion | variation in resistance value ratio can further be suppressed.

It is a front view which shows the magnetic sensor by the 1st Embodiment of this invention. It is sectional drawing which looked at the magnetic sensor from the arrow II-II direction in FIG. It is a circuit diagram which shows a magnetic sensor. It is explanatory drawing which shows the magnetic field which acts on a magnetic sensor. In a comparative example, it is a characteristic line figure showing the relation between the intensity of the Y direction component of a magnetic field, and the output voltage. It is a front view which shows the magnetic sensor by 2nd Embodiment. It is a front view which shows the magnetic sensor by 3rd Embodiment. It is explanatory drawing which shows the state which the magnetic field containing an X direction component acted on the magnetic sensor in FIG. It is explanatory drawing which shows the state which the magnetic field which does not contain an X direction component acted on the magnetic sensor in FIG. It is sectional drawing which looked at the magnetic sensor from the arrow XX direction in FIG. It is sectional drawing of the position similar to FIG. 10 which shows the magnetic sensor by a modification.

  Hereinafter, a magnetic sensor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The magnetic sensor 1 according to the first embodiment will be described with reference to FIGS. The magnetic sensor 1 includes a sensor circuit unit 2 made of a magnetic thin film magnetoresistive element and a differential amplifier 3, and is miniaturized by being integrated inside the package, and is formed as an AMR-IC (Anisotropic Magneto Resistance Integrated Circuit). The

  The sensor circuit unit 2 is formed, for example, on the surface of the substrate 4 extending along the X direction and the Y direction orthogonal to each other. The sensor circuit unit 2 is composed of four magnetoresistive elements R1 to R4. The magnetoresistive elements R1 to R4 are formed in a meander shape by alternately connecting a long strip-shaped pattern and a short strip-shaped pattern. The extending direction of the long strip pattern in the first and second magnetoresistive elements R1 and R2 extends along the X direction, and the resistance value becomes the smallest when a detection magnetic field in the Y direction which is the first direction is given. On the other hand, the elongated strip pattern extending in the third and fourth magnetoresistive elements R3 and R4 extends in the Y direction, and the resistance value is smallest when a detection magnetic field in the X direction, which is the second direction, is applied. Become. The magnetoresistive elements R1 to R4 are formed in a predetermined shape by using, for example, a micro processing technique such as a photolithography technique after depositing a permalloy (NiFe), which is a magnetoresistive material, on the substrate 4.

  As shown in FIG. 1, the first magnetoresistive element R <b> 1 is disposed and formed on the lower left side of the substrate 4, and the second magnetoresistive element R <b> 2 is disposed and formed on the upper right side of the substrate 4. The third magnetoresistive element R3 is disposed and formed on the upper left side of the substrate 4, and the fourth magnetoresistive element R4 is disposed and formed on the lower right side of the substrate 4.

  The first to fourth magnetoresistive elements R1 to R4 are connected by a full bridge to form a bridge circuit 5. Specifically, the first series circuit 6 is configured by connecting the first magnetoresistive element R1 and the third magnetoresistive element R3 in series via the first connection point P1. The second series circuit 7 is configured by connecting the second magnetoresistive element R2 and the fourth magnetoresistive element R4 in series via the second connection point P2.

  The first magnetoresistive element R1 side of the first series circuit 6 and the fourth magnetoresistive element R4 side of the second series circuit 7 are commonly connected via a third connection point P3. The third magnetoresistive element R3 side of the first series circuit 6 and the second magnetoresistive element R2 side of the second series circuit 7 are commonly connected via a fourth connection point P4. As a result, the first series circuit 6 and the second series circuit 7 are connected in parallel to form the bridge circuit 5.

  The third connection point P3 is electrically connected to a ground terminal 8 for connection to an external ground GND. Further, the drive voltage terminal 9 for supplying the drive voltage Vdd is electrically connected to the fourth connection point P4. As a result, the drive voltage Vdd serving as the power supply voltage is applied to the bridge circuit 5 via the third connection point P3 and the fourth connection point P4.

  On the other hand, the first connection point P1 and the second connection point P2 are electrically connected to output terminals 10 and 11 for extracting output voltages V1 and V2, respectively. Thereby, the bridge circuit 5 can take out the output voltages V1 and V2 accompanying the magnetic field change through the first connection point P1 and the second connection point P2.

  The input terminal of the differential amplifier 3 is connected to the first connection point P1 and the second connection point P2, respectively. The differential amplifier 3 differentially amplifies a potential difference generated between two input terminals, that is, a potential difference (V1−V2) between the output voltages V1 and V2, and outputs a detection signal Vout.

  An insulating film 12 made of an insulating material is formed on the surfaces of the first to fourth magnetoresistive elements R1 to R4. Further, a substantially quadrangular magnetic flux collecting means is provided on the surface of the insulating film 12 as a magnetic flux collecting means formed of a magnetic material so as to cover the third magnetoresistive element R3 and the fourth magnetoresistive element R4. A magnetic film 13 is provided.

  The magnetic flux collecting film 13 may be a metal film or a ceramic film formed by using a film forming means such as vapor deposition or sputtering, or may be a film coated with a resin mixed with magnetic powder. When the magnetic flux collecting film 13 is provided, the magnetic permeability of the magnetic flux collecting film 13, the thickness dimension, the distance from the magnetoresistive elements R 3 and R 4 (thickness dimension of the insulating film 12), etc. The ratio between the resistance values of the magnetoresistive elements R3 and R4 when applied and the resistance values of the magnetoresistive elements R3 and R4 when the magnetic field in the X direction having the same strength is applied when the magnetic flux collecting film 13 is not provided. Depending on the specifications of the magnetic sensor, it is set to a predetermined ratio or less, for example, 1/2 or less. In general, it is desirable that the magnetic flux collecting film 13 has a high magnetic permeability and a large thickness in order to enhance the magnetic flux collecting effect. Thus, when a magnetic field φ other than the Y direction is applied, the magnetic field φ is collected on the magnetic flux collecting film 13 to reduce the magnetic field φ applied to the third and fourth magnetoresistive elements R3 and R4. be able to.

  The magnetic sensor 1 according to the embodiment of the present invention has the above-described configuration. Next, a magnetic field detection operation will be described.

  First, a magnetic field detection operation of a magnetic sensor as a comparative example in which the magnetic flux collecting film 13 is not provided will be described. First, a magnetic field φ in the Y direction, which is composed only of the Y direction component φy and does not exist in the X direction component φx, is provided to the magnetic sensor. At this time, as the strength of the magnetic field φ increases, that is, as the positive Y-direction component φy increases, the resistance values of the first and second magnetoresistive elements R 1 and R 2 decrease. On the other hand, since the X-direction component φx does not exist even when the strength of the magnetic field φ increases, the resistance values of the third and fourth magnetoresistive elements R3 and R4 hardly change. Therefore, as indicated by the solid line in FIG. 5, as the intensity of the Y-direction component φy in the + direction increases, the output voltage V1 at the connection point P1 decreases and the output voltage V2 at the connection point P2 increases. In the case of the Y direction component φy in the − (minus) direction, which is different from the + direction by 180 degrees, the output characteristics are the same as those in the + direction Y direction component φy.

  Here, when the intensity of the Y-direction component φy is 0 (A / m) (φy = 0 (A / m)), the output voltage V1 at the connection point P1 is larger than the output voltage V2 at the connection point P2. The resistance values of the magnetoresistive elements R1 and R3 are set. As a result, when the intensity of the Y-direction component φy is near 0 (A / m), the detection signal Vout of the differential amplifier 3 is at a high level. When the intensity of the Y-direction component φy increases and reaches the operating point φy0, the output voltage V1 at the connection point P1 and the output voltage V2 at the connection point P2 become substantially the same value. When the intensity of the Y direction component φy increases beyond the operating point φy0, the output voltage V1 at the connection point P1 becomes smaller than the output voltage V2 at the connection point P2, and the detection signal Vout of the differential amplifier 3 is at the low level. Switch to.

  On the other hand, when a magnetic field φ tilted from the Y direction toward the X direction is applied, the resistance values of the first and second magnetoresistive elements R1 and R2 change according to the Y direction component φy of the direction of the magnetic field φ. As the strength of the Y direction component φy increases, the resistance values of the first and second magnetoresistive elements R1, R2 decrease. At this time, when the ± direction Y-direction component φy increases, the ± direction X-direction component φx also increases, and in addition, the third and fourth magnetic fields according to the intensity of the ± direction X-direction component φx of the magnetic field φ. Resistance values of the resistance elements R3 and R4 change.

  Therefore, as shown by the broken line in FIG. 5, when a magnetic field φ including a ± direction X-direction component φx is applied, even if the intensity of the ± direction Y-direction component φy changes, the connection points P1, P2 Changes in the output voltages V1 and V2 are reduced. As a result, the intensity of the Y-direction component φy of the magnetic field φ when the detection signal Vout of the differential amplifier 3 switches from the Low level to the High level, that is, the operating point φy1, is given the magnetic field φ of only the Y-direction component φy. The operating point becomes larger than the operating point φy0, and the magnetic field detection sensitivity tends to decrease.

  Next, the magnetic field detection operation in the magnetic sensor 1 according to the present embodiment will be described. Also in the magnetic sensor 1 according to the present embodiment, when a magnetic field φ that does not include the ± direction X-direction component φx is applied, a detection operation substantially similar to that of the comparative example described above is performed. For this reason, as the intensity of the Y direction component φy in the ± direction of the magnetic field φ increases, the output voltage V1 at the connection point P1 decreases and the output voltage V2 at the connection point P2 increases. When the intensity of the Y direction component φy in the ± direction is smaller than the operating point φy0, the detection signal Vout of the differential amplifier 3 is at a high level, and when the intensity of the Y direction component φy is larger than the operating point φy0, The detection signal Vout of the amplifier 3 becomes a low level.

  On the other hand, when the magnetic field φ including the ± direction X-direction component φx is applied, the magnetic sensor 1 according to the present embodiment, unlike the comparative example, reduces the influence of the ± direction X-direction component φx, A near detection operation can be performed when a magnetic field φ of only Y-direction component φy is given.

  Specifically, in the magnetic sensor 1 according to the present embodiment, the magnetic flux collecting film 13 is provided on the surfaces of the third and fourth magnetoresistive elements R3 and R4. For this reason, when a magnetic field φ tilted from the ± Y direction is applied, the magnetic field φ acts on the first and second magnetoresistive elements R 1 and R 2 as they are, whereas the third and fourth magnetisms. The magnetic field φ in the vicinity of the resistance elements R3 and R4 is attracted to the magnetic flux collecting film 13 and hardly acts on the third and fourth magnetoresistance elements R3 and R4. As a result, even when the magnetic field φ including the X direction component φx in the ± direction is applied, the change in the resistance value of the third and fourth magnetoresistive elements R3 and R4 can be reduced. The output voltages V1 and V2 can be changed mainly by the Y direction component φy in the ± direction while suppressing the influence of the direction component φx. Therefore, even when the magnetic field φ including the X-direction component φx is applied, the operating point when the detection signal Vout of the differential amplifier 3 switches from the high level to the low level is given by the magnetic field φ of only the Y-direction component φy. Therefore, the operating point φy0 can be approached, and the operating point variation can be reduced.

  The first to fourth magnetoresistive elements R1 to R4 can all be formed with the same pattern line width and thickness. For this reason, even when processing variations occur when forming the magnetoresistive elements R1 to R4, the first and second magnetoresistive elements R1 and R2 and the third and fourth magnetoresistive elements R3 and R4 Therefore, since the resistance value ratio hardly changes, the variation of the resistance value ratio can be suppressed, and the characteristic variation for each sensor can be reduced. Further, by arranging the pattern line width and thickness of the first to fourth magnetoresistive elements R1 to R4 and the film forming materials, the temperature resistance coefficients of the first to fourth magnetoresistive elements R1 to R4 are arranged. Can be made almost constant. In addition, the current concentrates near the surface of each magnetoresistive element due to the skin effect. However, by aligning the pattern line widths and thicknesses of the first to fourth magnetoresistive elements R1 to R4, The effect of the skin effect on the element is almost constant. As a result, it is possible to reduce variations in temperature coefficients related to the first to fourth magnetoresistive elements R1 to R4 constituting the magnetic sensor 1.

  Next, FIG. 6 shows a magnetic sensor according to the second embodiment. The feature of the second embodiment is that the first magnetic flux collecting means is provided on the surfaces of the first and second magnetoresistive elements, and the second magnetic flux having a larger permeability than the first magnetic flux collecting means. The magnetism collecting means is provided on the surfaces of the third and fourth magnetoresistive elements. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Similar to the magnetic sensor 1 according to the first embodiment, the magnetic sensor 21 according to the second embodiment includes a sensor circuit unit 2, and the sensor circuit unit 2 includes first and third magnetoresistive elements. The bridge circuit 5 includes a first series circuit 6 in which R1 and R3 are connected in series and a second series circuit 7 in which the second and fourth magnetoresistive elements R2 and R4 are connected in series. . The surfaces of the first to fourth magnetoresistive elements R1 to R4 are covered with the insulating film 12.

  On the surfaces of the first magnetoresistive element R1 and the second magnetoresistive element R2, a first magnetic flux collecting film 22 is formed as a first magnetic flux collecting means made of a magnetic material with the insulating film 12 interposed therebetween. The A second magnetic flux collecting film 23 as a second magnetic flux collecting means made of a magnetic material is sandwiched between the surfaces of the third magnetoresistive element R3 and the fourth magnetoresistive element R4. It is formed. The magnetic permeability of the second magnetic flux collecting film 23 is larger than the magnetic permeability of the first magnetic flux collecting film 22.

  Thereby, when a magnetic field in a direction different from the detection magnetic field in the Y direction is applied, the magnetic field applied to the first and second magnetoresistive elements R 1 and R 2 is collected in the first magnetic flux collecting film 22. The amount of the magnetic field applied to the third and fourth magnetoresistive elements R 3 and R 4 is collected by the second magnetic flux collecting film 23 is larger than the amount of the magnetic flux collecting film 23. As a result, the change in resistance value of the third and fourth magnetoresistive elements R3, R4 can be reduced compared to the change in resistance value of the first and second magnetoresistive elements R1, R2.

  Thus, the second embodiment can provide the same effects as those of the first embodiment.

  Next, FIGS. 7 to 10 show a magnetic sensor according to a third embodiment. A feature of the third embodiment is that a yoke is provided on the third and fourth connection point sides so as to sandwich the first series circuit and the second series circuit. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Similar to the magnetic sensor 1 according to the first embodiment, the magnetic sensor 31 includes a sensor circuit unit 2, and the sensor circuit unit 2 includes a first magnetoresistive element R 1 and a third magnetoresistive element R 3 connected in series. 1 and a bridge circuit 5 in which a second series circuit 7 in which the second and fourth magnetoresistive elements R2 and R4 are connected in series is connected in parallel.

  The surfaces of the first to fourth magnetoresistive elements R1 to R4 are covered with the insulating film 12. A magnetic flux collecting film 13 made of a magnetic material is formed on the surfaces of the third magnetoresistive element R3 and the fourth magnetoresistive element R4 with the insulating film 12 interposed therebetween.

  The yokes 32 and 33 are formed in an elongated block shape using a magnetic material. The yokes 32 and 33 are provided separately from the chip-like substrate 4 and are disposed at positions sandwiching the substrate 4 from both sides in the Y direction. At this time, the yoke 32 is disposed on the third connection point P3 side (lower side of the substrate 4 in FIG. 7), and the yoke 33 is disposed on the fourth connection point P4 side (upper side of the substrate 4 in FIG. 7). Is done. The yokes 32 and 33 sandwich the first series circuit 6 and the second series circuit 7 from both sides of the magnetic field detection direction, that is, the Y direction.

  The lengths of the yokes 32 and 33 in the X direction are obtained by adding the lengths of the first and third magnetoresistive elements R1 and R3 and the lengths of the fourth and second magnetoresistive elements R4 and R2. It is formed larger than the value, specifically, larger than the substrate 4. Further, the thickness dimension of the yokes 32 and 33 is formed larger than the height dimension including the magnetoresistive elements R1 to R4 and the substrate 4, for example. Thus, when the substrate 4 is viewed from the Y direction, the entire magnetoresistive elements R1 to R4 are hidden by the yokes 32 and 33.

  Thus, the third embodiment can provide the same operational effects as those of the first embodiment. In particular, in the third embodiment, the yokes 32 and 33 are provided on the third and fourth connection points P3 and P4 side so as to sandwich the first series circuit 6 and the second series circuit 7, respectively. As shown in FIGS. 8 and 9, a magnetic field can be formed between the yokes 32 and 33 along the Y direction. For this reason, since the Y direction component of the magnetic field can be increased and the X direction component can be reduced, fluctuations in the operating point of the magnetic sensor 31 and variations in the resistance value ratio can be further suppressed. Further, similarly to the first and second embodiments, it is possible to reduce variations in temperature coefficients related to the first to fourth magnetoresistive elements R1 to R4.

  Although the yokes 32 and 33 are provided separately from the substrate 4 in the third embodiment, the yokes 43 and 44 are provided on the substrate 42 like the magnetic sensor 41 according to the modification shown in FIG. It is good also as a structure to provide. In this case, the external dimensions of the magnetic sensor 41 can be reduced as compared with the case where the yokes 32 and 33 are provided separately from the substrate 4 as in the third embodiment.

  In each of the above-described embodiments, the magnetic flux collecting means is configured by the magnetic flux collecting films 13, 22, and 23 formed on the surface of the insulating film 12, but for example, a plate-like magnetic material adhered and fixed to the surface of the insulating film 12 The magnetic flux collecting means may be constituted by the body pieces.

  In each of the above embodiments, the magnetic sensors 1, 21 and 31 are configured to integrate the sensor circuit unit 2 having the magnetoresistive elements R1 to R4 and the differential amplifier 3. The configuration may be omitted.

  In each of the above embodiments, the first to fourth magnetoresistive elements R1 to R4 are configured to alternately connect a plurality of linear patterns formed in close proximity to each other at the tip. However, the present invention is not limited to this. For example, the magnetoresistive elements R1 to R4 may be configured by one linear pattern.

1, 2, 31, 41 Magnetic sensor 4, 42 Substrate 6 First series circuit 7 Second series circuit 13 Magnetic flux collecting film (magnetic flux collecting means)
22 First magnetic flux collecting film (first magnetic flux collecting means)
23 Second magnetic flux collecting film (second magnetic flux collecting means)
32, 33, 43, 44 Yoke R1 1st magnetoresistive element R2 2nd magnetoresistive element R3 3rd magnetoresistive element R4 4th magnetoresistive element P1 1st connection point P2 2nd connection point P3 2nd 3 connection points P4 4th connection point

Claims (3)

A first and second magnetoresistive elements whose resistance value changes to the maximum when a detection magnetic field in the first direction is applied; and third and fourth magnetoresistive elements;
A first series circuit formed by connecting the first magnetoresistive element and the third magnetoresistive element in series via a first connection point; the second magnetoresistive element; and the fourth magnetism. A second series circuit formed by connecting a resistive element in series via a second connection point, the first magnetoresistive element side of the first series circuit, and the second series circuit of the second series circuit; 4 and the second magnetoresistance element side of the first series circuit and the second magnetoresistance element of the second series circuit are connected in common through a third connection point. The element side is connected in common through the fourth connection point,
In a magnetic sensor for applying a power supply voltage through the third connection point and the fourth connection point and extracting an output voltage accompanying a magnetic field change through the first connection point and the second connection point ,
Magnetic flux collecting means is provided on the surfaces of the third and fourth magnetoresistive elements,
When a magnetic field in a direction different from the detection magnetic field in the first direction is applied, the magnetic field applied to the third and fourth magnetoresistive elements is collected in the magnetic flux collecting means, and the third and A magnetic sensor characterized by reducing a change in the resistance value of the fourth magnetoresistive element. A first and second magnetoresistive elements whose resistance value changes to the maximum when a detection magnetic field in the first direction is applied; and third and fourth magnetoresistive elements;
A first series circuit formed by connecting the first magnetoresistive element and the third magnetoresistive element in series via a first connection point; the second magnetoresistive element; and the fourth magnetism. A second series circuit formed by connecting a resistive element in series via a second connection point, the first magnetoresistive element side of the first series circuit, and the second series circuit of the second series circuit; 4 and the second magnetoresistance element side of the first series circuit and the second magnetoresistance element of the second series circuit are connected in common through a third connection point. The element side is connected in common through the fourth connection point,
In a magnetic sensor for applying a power supply voltage through the third connection point and the fourth connection point and extracting an output voltage accompanying a magnetic field change through the first connection point and the second connection point ,
Providing first magnetic flux collecting means on the surfaces of the first and second magnetoresistive elements;
A second magnetic flux collecting means having a larger magnetic permeability than the first magnetic flux collecting means is provided on the surfaces of the third and fourth magnetoresistive elements;
The amount by which the magnetic field applied to the first and second magnetoresistive elements is collected by the first magnetic flux collecting means when a magnetic field in a direction different from the detected magnetic field in the first direction is applied. In comparison with the above, the magnetic field applied to the third and fourth magnetoresistive elements is increased in amount collected by the second magnetic flux collecting means,
A magnetic sensor characterized in that a change in resistance value of the third and fourth magnetoresistive elements is reduced as compared with a change in resistance value of the first and second magnetoresistive elements.   The magnetic sensor according to claim 1, wherein a yoke is provided on the third and fourth connection point sides so as to sandwich the first series circuit and the second series circuit.

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