JP5707971B2 - Magnetic sensor controller - Google Patents

Description

  The present invention relates to a magnetic sensor control device. More specifically, the present invention relates to a magnetic sensor control device including a magnetic sensor using a spintronic element such as a tunnel magnetoresistive element and a control circuit for the magnetic sensor.

  Conventionally, sensors using various magnetoresistive elements have used magnetoresistive elements (MR elements, etc.), magnetoimpedance elements (MI elements), and the like. For example, according to the MI sensor, the use of a magnetoresistive element called an MI element facilitates thinning and miniaturization, and improvements are being actively made. In the case of this MI element, it is possible to detect the magnetic field strength by changing the high frequency impedance due to the magnetic field when a high frequency current is passed, and it is necessary to make full use of circuit technology, but the sensor sensitivity is high. Have.

  Further, giant magnetoresistive elements (GMR elements), tunnel magnetoresistive elements (TMR elements), and the like are known as elements of magnetic sensors (magnetoresistance sensors) using magnetoresistive elements (MR elements). A GMR (Giant magnetic resistance) element includes a case where a plurality of ferromagnetic layers and non-ferromagnetic layers are alternately formed, and the magnetization directions of two adjacent magnetic layers are parallel according to the strength of an external magnetic field. Magnetic detection is performed by using a resistance that varies depending on the antiparallel case. In addition, a TMR (tunnel Magneto-Resistance) element is formed by forming a plurality of magnetic thin film layers through an insulating layer and conducting electrons through conduction through a tunnel phenomenon while maintaining spin. Magnetic field detection is performed by utilizing the fact that the tunnel transmission coefficient differs depending on the state of magnetization.

  These magnetoresistive elements include a pinned layer (fixed layer) whose magnetization direction and strength are fixed in a predetermined direction, and a free layer (free layer) whose magnetization direction changes according to the direction of the external magnetic field. Yes. When an external magnetic field is detected as a magnetic sensor, the relative value of the magnetization direction of the free layer that changes according to the direction of the external magnetic field with respect to the magnetization direction of the fixed pinned layer, and the resistance value changes according to the strength of magnetization. This is to detect the direction of the magnetic field.

  With respect to a magnetic sensor using such a magnetoresistive element, for example, Patent Document 1 and Patent Document 2 disclose a magnetic sensor in which a plurality of magnetoresistive elements as sensors are arranged in series in order to increase the resolution to a detection target. Has been. Patent Document 3 discloses a magnetic sensor having a magnetoresistive element composed of a TMR element and capable of detecting a vector component in the Z-axis direction other than the plane of the magnetic surface even when the sensor is arranged on a plane. Yes. Patent Document 4 discloses a current sensor that includes a magnetoresistive element and a thin film coil and measures a detection target current flowing through the thin film coil.

  Up to now, spintronics elements such as TMR elements have been considered to have a large rate of change with respect to the magnetic field, but the low frequency noise peculiar to electronic devices has been considered to be large. It has been found that it can function as a sensing element up to the limit of processing. However, there is still room for study on techniques for reducing noise and increasing sensitivity in magnetic sensors using spintronic elements such as TMR elements.

The present invention provides a magnetic sensor using a magneto-resistive element, a magnetoresistive element group connect the magnetoresistive elements in parallel or in series, the cells connected to said magnetoresistive element element group in parallel as a detection unit It is an object of the present invention to provide a magnetic sensor control device that can reduce noise and increase detection sensitivity in accordance with the measurement target of the magnetic sensor.

To achieve the above object, a magnetic sensor control device according to claim 1, the magneto-resistive element group by connecting a plurality of magnetoresistive elements in parallel or in series, and connecting a plurality of magnetoresistive element element group in parallel A detector having a cell, the cells being connected in parallel and / or in series, a first switch for switching connection of at least one of the magnetoresistive elements, and at least one of the cells A second switch unit that switches connection, and a magnetic sensor that detects a current of the current source using a magnetic field generation source as a current source, and a first switch based on the frequency, amplitude, and phase signals of the current parts and / or a switch changeover section for switching the second switch unit, line detection by selecting sequentially different combinations magnetoresistive element group and / or the cell by the switch changeover section If the detection accuracy satisfies a predetermined noise-to-signal output condition, detection is performed with the combination selected at that time, and if the predetermined noise-to-signal output condition is not satisfied, another combination is selected. And a control means for repeating the detection .

Further, an invention according to claim 2, in the magnetic sensor control device according to claim 1, in the vicinity of the detecting section is provided an alternating magnetic field application unit, a magnitude of the external magnetic field of the magnetoresistive element constituting the detection unit varied, the control means, the frequency of the current, based on the amplitude and phase of the signal, and controls the AC magnetic field applying unit.

Further, the invention according to claim 3, in the magnetic sensor control device according to claim 1, the detection unit is arranged together with the piezoelectric element to a substrate, to vibrate the substrate by applying an AC voltage to the piezoelectric element, the detection unit varying the magnitude of the external magnetic field of the magnetoresistive element constituting the control means, the frequency of the current, based on the amplitude and phase of the signal, and controls the piezoelectric element.

The invention of claim 4 is the magnetic sensor control device according to claim 1, the movable portion having a hard magnetic part made of a hard magnetic material in the vicinity of the detection portion is provided, the drive of the movable portion displaces the hard magnetic part, varying the magnitude of the external magnetic field of the magnetoresistive element constituting the detection unit, the control means, the frequency of the current, based on the amplitude and phase of the signal, controls the moving part Is.

According to a fifth aspect of the present invention, in the magnetic sensor control device according to the first aspect of the present invention, a movable portion having a soft magnetic body portion made of a soft magnetic material and a coil member is provided in the vicinity of the detection portion, and the coil member is provided. Controlling the magnitude of the external magnetic field of the magnetoresistive element that constitutes the detection unit by displacing the soft magnetic unit by applying a direct current and driving the movable unit while the soft magnetic unit is magnetized It means the frequency of the current, based on the amplitude and phase of the signal, and controls the moving unit.

According to a sixth aspect of the present invention, in the magnetic sensor control device according to any one of the first to fifth aspects, the control means detects a power consumption of the device and / or an applied voltage. The magnetic sensor is controlled based on detection by the power detection unit.

According to a seventh aspect of the present invention, in the magnetic sensor control device according to the sixth aspect of the present invention, the control means includes a battery unit serving as a power source for the device, based on detection by the power detection unit and the battery unit. It controls the magnetic sensor.

Further, the invention according to claim 8 is the magnetic sensor control device according to claim 6 or 7 , wherein the control means includes an external energy passive unit that passively passes external energy serving as a power source of the device, The magnetic sensor is controlled based on detection by the power detection unit and an external energy passive unit.

  ADVANTAGE OF THE INVENTION According to this invention, according to the measuring object of a magnetic sensor, noise can be reduced and the high sensitivity of detection can be achieved.

It is a schematic diagram of the element part for a detection by a TMR layer structure. It is a schematic diagram of the element part for a detection by GMR layer structure. It is a schematic diagram which shows an example of the magnetic sensor which has arrange | positioned the detection element in series. It is explanatory drawing of the wiring method in the case of series connection. It is a schematic diagram which shows the other example of the magnetic sensor which has arrange | positioned the detection element in series. It is a schematic diagram which shows an example of the magnetic sensor which has arrange | positioned the detection element in parallel. It is a schematic diagram which shows the other example of the magnetic sensor which has arrange | positioned the detection element in parallel. It is a schematic diagram which shows an example of the magnetic sensor which has arrange | positioned the element arrangement | sequence part complexly. It is a flowchart (1) which shows the process which a magnetic sensor control apparatus performs. It is a functional block diagram (1) of a magnetic sensor control apparatus. It is a schematic diagram which shows an example of the magnetic sensor which has an alternating current magnetic field application part. It is a schematic diagram which shows an example of the magnetic sensor which has a piezoelectric element. It is a schematic diagram which shows an example of the magnetic sensor which has a movable part. It is a schematic diagram which shows the other example of the magnetic sensor which has a movable part. It is a functional block diagram (2) of a magnetic sensor control apparatus. It is a flowchart (2) which shows the process which a magnetic sensor control apparatus performs. It is a functional block diagram (3) of a magnetic sensor control apparatus. It is a functional block diagram (4) of a magnetic sensor control apparatus.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(Detection element configuration)
1 and 2 show a configuration example of a detection element section (hereinafter also referred to as a magnetoresistive element, a detection element, or an element). The detection element section 10 shown in FIG. 1 has a TMR layer configuration including a cap layer 7, a free layer 6, a tunnel layer 5 A, a pinned layer 4, an antiferromagnetic (AFM) layer 3, a seed layer 2, and a substrate 1. 1 is an example of an element unit 10.

  As the substrate 1, for example, Si or a thermally oxidized substrate on Si is used. Also, an AFM layer 3 made of a seed layer 2 such as Ta, FeMn, PtMnIrMn, NiMn, PdPtMn, CrPtMn, CoMn, or an alloy thereof using an ultrahigh vacuum sputtering device, an ion beam sputtering device, an EB vapor deposition device, or the like. Configure. The thickness is set to about 3 nm to 400 nm or more depending on each design value, but 10 nm to 100 nm is preferable. In addition, the pinned layer 4 (synthetic ferri layer) is provided above the AFM layer 3 (spin valve configuration).

  The tunnel layer 5A is made of, for example, Al—O or MgO, and the thickness is designed between 0.5 nm to 6 nm, but 1 nm to 4 nm is preferable. Here, if the structure is made of MgO, an excellent magnetoresistance change rate characteristic can be obtained even with a relatively thick film thickness. Therefore, if it is desired to increase the resistance value, it can be realized by increasing the thickness. Have Although not shown, when the MgO layer is used as the tunnel layer 5A, for example, it is preferable that an amorphous film such as CoFeSiB is formed as-deposited and then crystallized during annealing. By doing so, the rearrangement of MgO is promoted to increase the crystallinity, whereby the rate of change in magnetoresistance can be remarkably improved, and the detection performance can be further improved.

  By forming the free layer 6 with a soft magnetic characteristic such as NiFe, CoFe, CoNiFe, CoZrNb, etc., it is possible to exhibit sensor characteristics. Further, as the cap layer 7, Ta or the like is formed.

  The detection element unit 10 is completed by forming a shape into a desired shape by fine processing using photolithography, EB exposure, and the like, and arranging electrodes on the upper and lower sides.

  Note that the detection element unit 10 in the present embodiment is not limited to the TMR layer configuration shown in FIG. 1, and may have a GMR layer configuration as shown in FIG. 2, for example. The detection element unit 10 shown in FIG. 2 has a nonmagnetic metal layer 5B instead of the tunnel layer 5A, and the other layer configuration is the same. Here, for example, Cu, Ag or the like is suitable for the nonmagnetic metal layer 5B.

(Magnetic sensor configuration)
As will be described in detail below, the magnetic sensor 20 is a magnetic sensor composed of magnetoresistive elements, which is configured to have a double layer and function as a sensor in which the magnetoresistive elements are arranged in parallel or in series ( A magnetoresistive element group), which has a sensor in which these groups are further paralleled to form a cell, and combines or separates outputs according to the functional state of each cell. In other words, the sensor is composed of element groups and has a double hierarchy so that it can be easily arranged. Therefore, it is possible to appropriately detect the noise-to-signal output according to the measurement target, and to make the detection information more sophisticated. It can be obtained.

  FIG. 3 shows an example of the magnetic sensor 20. In the magnetic sensor 20, the detection elements 10 are arranged in series to form a magnetoresistive element group 8 (8a, 8b, 8c...), And these are arranged in parallel to form a cell (detection unit, element arrangement unit) 9. The magnetoresistive element group 8 is interlocked. By doing so, the resistance value can be increased in proportion to the number of elements. Further, by arranging the reference resistor (fixed resistor) 11 in series, it is possible to realize an output change as the magnetic resistance value changes.

  Furthermore, since the connection is made in series, a change in the voltage of the connected elements can be obtained with the same voltage, which greatly contributes to the high sensitivity of the sensor. In addition, as a method of series connection, either a method of flowing current to the elements alternately as shown in FIG. 4A or a method of flowing current in the same direction as shown in FIG. Also good.

  Further, as shown in FIG. 5, it is also preferable that a switch (switch unit 13) is further arranged on the magnetic sensor 20 shown in FIG. Here, the switch can be composed of, for example, a CMOS or the like.

  By operating in conjunction with the element group as described above, it is possible to increase the sensitivity of the magnetic sensor and reduce 1 / f noise.

  FIG. 6 shows another example of the magnetic sensor 20. As shown in FIG. 6, the detection elements 10 are arranged in parallel to form a magnetoresistive element group 8 (8a, 8b, 8c...), And these are arranged in parallel to form a cell (detection unit, element arrangement unit) 9. These may be linked together. By arranging the elements in parallel in this way, it is possible to reduce noise, particularly 1 / f noise. Further, as shown in FIG. 7, it is also preferable that a switch (switch unit 13) is further arranged on the magnetic sensor 20 shown in FIG. 6.

  Further, as shown in FIG. 8, a parallel arrangement of element arrangement portions 9a (FIG. 6) and a serial arrangement of element arrangement portions 9b (configuration with a switch portion shown in FIG. 5) are arranged in a composite manner. It is also preferable that the arrangement of the arrangement part can be appropriately changed by the switch part 14. Using the magnetic sensor 20 configured in this manner, the detection area as a sensor is appropriately changed by varying the target noise characteristics, the required signal output, and the number of detectable elements, and the detection performance of the sensor Can be improved. For example, it is possible to realize a detection method such as causing an element to function only in a region where a signal is large.

  Further, in the example shown in FIG. 8, the number of layers of each element is 2, but it is also preferable to perform parallelization or serialization by further grouping them. For example, each of the sensing elements 10 shown in FIG. 1 may be replaced with a parallel element. In such fine processing, for example, fine processing on the nanometer (nm) order such as electron beam exposure process or patterning using a self-assembled film may be performed. In this way, by multiplexing the hierarchy, further noise reduction and higher sensitivity can be achieved.

(Magnetic sensor control)
Hereinafter, control (control method) of the magnetic sensor 20 executed by the magnetic sensor control device 40 (a control circuit including the magnetic sensor 20) will be described. The processing executed by the magnetic sensor control device 40 of this embodiment is shown in the flowchart of FIG.

  FIG. 10 shows an example of a functional block diagram of the magnetic sensor control device 40. In order to execute the processing shown in FIG. 9, the magnetic sensor control device 40 includes a control unit 41 that executes various controls based on the sensor output from the magnetic sensor 20, and the control unit 41 includes a switch unit. And a switch switching unit 42 for controlling 13 and 14, and a storage unit (memory) 43 for primary storage of frequency, amplitude and phase detection contents.

  Here, when a target detection signal is detected as a current source, it can be regarded as a “true” current source, and when it is assumed to be a current source through analysis, it can be regarded as an “effective” current source. . Therefore, the magnetic sensor control device 40 according to the present embodiment switches the element unit in accordance with the frequency, amplitude, and phase of the current source at that time to increase the detection output.

  The control means 41 first detects a magnetic field (S1), and detects its frequency, amplitude and phase (S2). These are temporarily stored in the storage unit 43.

  Next, the switch unit is switched by the switch switching unit 42, and the cells 9 (and / or the magnetoresistive element group 8) are appropriately selected in different combinations (S3), detected by the selected elements, and a new magnetic field (different) Magnetic field) is detected (S4), and a new frequency, amplitude, and phase (different frequency, amplitude, and phase) are detected (S5).

  When a predetermined setting condition (for example, the detection accuracy satisfies a desired accuracy) is satisfied (S7: Yes), detection is performed with the element configuration selected at that time. On the other hand, when the setting condition is not satisfied (S7: No), the process returns to S3, the detection element is selected again, and the processing (S3 to S7) is repeated until the setting condition is satisfied.

  By controlling the magnetic sensor 20 in this way, the detection output of the magnetic sensor 20 that can detect the noise-to-signal output in accordance with the measurement target can be increased, and highly accurate detection information can be obtained. In addition, since the magnetic sensor 20 is controlled so that optimum sensing can be performed in accordance with the measurement object, various measurement objects can be used over a long period of time.

(Second Embodiment)
Hereinafter, other embodiments of the magnetic sensor 20 will be described. A description of the same points as in the above embodiment will be omitted. In addition, the arrangement of detection elements (series and parallel), the presence / absence of a switch unit, and the like can be combined as appropriate in the configuration described below.

  A magnetic sensor 20 shown in FIG. 10 includes, in addition to the sensing element 10, a coil unit (AC magnetic field application unit) 16 for applying an alternating current (AC) magnetic field, and a current source for applying an alternating current (AC) magnetic field to the coil unit 16. 17 is added. By configuring in this manner, it is possible to realize detection by superimposing an AC magnetic field from the outside on the detection element 10 and shifting the effective frequency region to be detected. Reduction can be achieved.

  Further, the magnetic sensor 20 shown in FIG. 10 is used to execute the processing shown in FIG. 9 and the AC magnetic field application unit 16 is controlled by the control means 41 (the frequency, intensity, Further, the sensitivity can be further increased by changing the phase).

(Third embodiment)
A magnetic sensor 20 shown in FIG. 11 is provided with a detection unit on a substrate 19 on which a piezoelectric element 18 is arranged, and the piezoelectric element 18 includes an electrode unit 21 for applying a driving voltage. In the magnetic sensor 20 configured as described above, a driving voltage (alternating voltage) is applied to the electrode portion 21 by the driving voltage source 22 to drive the piezoelectric element 18 and mechanically vibrate the entire substrate 19 at a constant period. Let

  Furthermore, it is also preferable to arrange a direct current (DC) magnetic field applying coil section 23 and a direct current (DC) magnetic field applying current source 24 so that a direct current magnetic field can be applied. In addition, it is good also as a structure which can select the presence or absence of DC magnetic field application in the state which has arrange | positioned the coil part 23 for DC magnetic field application, and the current source 24 for DC magnetic field application.

  By adopting such a configuration, it is possible to detect in a state where an AC component is superimposed by vibrating externally, and therefore noise reduction, particularly 1 / f noise reduction, can be achieved. In addition, application of an alternating magnetic field by a piezoelectric element is simple, and the degree of freedom of design parameters is magnetically large, so that efficient noise reduction can be realized.

  Further, the process shown in FIG. 9 is executed using the magnetic sensor 20 shown in FIG. 11, and the piezoelectric element 18 is controlled by the control means 41 (a machine by applying an alternating voltage of the piezoelectric element to be superposed from the outside) By changing the frequency, intensity, and phase of vibration), higher sensitivity can be realized.

  In the present embodiment, the piezoelectric element 18 is disposed as a means for mechanically applying vibration at a constant period. However, the present invention is not limited to this, and for example, a drive system (electrostatic type) used in other MEMS technology or the like. It is also preferable to use a driving method, an electromagnetic driving method, or the like.

(Fourth embodiment)
12A is a top view, and FIG. 12B is a cross-sectional view. The magnetic sensor 20 includes a hard magnetic body portion 28 made of a hard magnetic material on a movable portion 27 fixed to a frame 26 by a flexible beam portion 25. Further, the movable portion 27 is also connected to a piezoelectric element portion including a piezoelectric element and a beam portion 29. Furthermore, the movable portion 27 can be bent by a piezoelectric element application wiring and a power source (not shown), and as a result, the hard magnetic body portion 28 can be displaced. Note that all or part of the movable portion 27 may be made of a magnetic material made of a hard magnetic material.

  That is, in the detection unit 9 on the substrate 30, since the magnetic field intensity from the hard magnetic body unit 28 periodically varies, an external magnetic field is substantially detected in the AC magnetic field. Therefore, it is possible to make the effective operating frequency function where there is a smaller amount of noise, particularly 1 / f noise component, and as a result, it is possible to realize more sensitive detection. In addition, the sensitivity of measurement can be increased by changing the bending frequency according to the measurement object.

  With such a configuration, it is possible to greatly increase the amplitude of the movable portion 27 and to set a large design parameter for noise reduction.

  Further, the magnetic sensor 20 shown in FIG. 12 is used to execute the processing shown in FIG. 9 and the control means 41 controls the movable portion 27 (the frequency, intensity, and By making the phase variable), it is possible to achieve higher sensitivity.

(Fifth embodiment)
13A is a top view, and FIG. 13B is a cross-sectional view. The magnetic sensor 20 includes a soft magnetic material portion 31 made of a soft magnetic material on a movable portion 27 fixed to a frame 26 by a flexible beam portion 25. In addition, a coil portion 32 for magnetizing the soft magnetic material is disposed, and the movable portion 27 is also connected to a piezoelectric element portion and a beam portion 29 including a piezoelectric element. Further, the movable portion 27 can be bent by a piezoelectric element application wiring and a power source (not shown), and as a result, the soft magnetic body portion 31 and the coil portion 32 can be displaced. The coil unit 32 is connected to a DC power source unit (not shown), and the soft magnetic body unit 31 can be magnetized by passing a current through the coil unit 32. Note that all or part of the movable portion 27 may be made of a magnetic material made of a soft magnetic material.

  That is, in the detection unit 9 on the substrate 30, the magnetic field strength of the magnetic field by the soft magnetic body unit 31 and the coil unit 32 periodically varies, so that an external magnetic field is substantially detected in the AC magnetic field. Become. Therefore, it is possible to make the effective operating frequency function where there is a smaller amount of noise, particularly 1 / f noise component, and as a result, it is possible to realize more sensitive detection. In addition, the sensitivity of measurement can be increased by changing the bending frequency according to the measurement object. Furthermore, by changing the current flowing through the coil section 32 from DC to AC, it is possible to superimpose a double cycle, and noise can be reduced depending on the measurement target.

  With such a configuration, the design parameter for noise reduction can be set larger. In addition, noise can be reduced at a plurality of frequencies.

  In addition, the magnetic sensor 20 shown in FIG. 13 is used to execute the processing shown in FIG. 9 and the control means 41 controls the movable portion 27 (the frequency, intensity, and By making the phase variable), it is possible to achieve higher sensitivity.

  According to the magnetic sensor control device 40 described in the first to fifth embodiments, the switch switching unit 42 appropriately switches the switch units 13 and 14, thereby depending on the detection target and the detection result. The magnetoresistive element group 8 and the cell 9 can be selectively set, and the detection position and detection area of the magnetic sensor 20 can be switched. Depending on the switching direction, the sensitivity can be increased, detection along the detection target can be performed, and high detection sensitivity of the magnetic sensor 20 can be achieved. For example, vector components can be analyzed by being close to a current source that generates a magnetic field or by analyzing the magnetic field, and the directionality of the magnetic field can be detected to achieve high detection sensitivity.

(Other embodiments)
Furthermore, as shown in FIG. 15, the magnetic sensor control device 40 preferably includes a power detection unit 44 that detects power consumption and applied voltage of the device. In the process executed by the magnetic sensor control device 40 including the power detection unit 44, a process (S17) in which the power detection unit 44 detects power consumption is added as shown in the flowchart of FIG. A description of the same processing as that in the flowchart of FIG. 9 is omitted.

  According to this magnetic sensor control device 40, it is possible to perform sensing while detecting the power consumption (current consumption, applied voltage) of the entire device, so that the detection sensitivity is high while optimizing the power consumption. Can be realized. Furthermore, the power consumption can be optimized while maintaining the value of the detection signal based on each detection data after dividing the detection unit into each part so as to detect the directionality.

  Moreover, the magnetic sensor control device 40 includes a battery unit 45 that is composed of a primary battery and / or a secondary battery and serves as a power source of the apparatus, as shown in FIG. By performing drive control using the battery 44 and the battery unit 45, it can function as an autonomous sensor that reduces power consumption.

  Furthermore, as shown in FIG. 18, an external energy passive unit (external magnetic field energy absorbing antenna) 46 that passively passes energy (driving source) from the outside is provided, and drive control is performed using the power detection unit 44 and the battery unit 45. Thus, the power consumption is reduced, and the sensor functions as an autonomous sensor that can be driven for a longer period. In order to detect the direction further, the detection unit is divided into parts and the power consumption is optimized while maintaining the value of the detection signal based on the detection data. Can be

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Seed layer 3 AFM layer 4 Pinned layer 5A Tunnel layer 5B Nonmagnetic metal layer 6 Free layer 7 Cap layer 8 Magnetoresistive element group 9, 9a, 9b Cell (element arrangement part, detection part)
DESCRIPTION OF SYMBOLS 10 Detection element part 11 Reference resistance 12 Wiring 13,14 Switch part 16 AC magnetic field application coil part 17 AC magnetic field application current source 18 Piezoelectric element 19 Substrate 20 which arranged the piezoelectric element Magnetic sensor 21 Electrode part for voltage application for driving 22 Driving power supply 23 DC magnetic field applying coil section 24 DC magnetic field applying current source 25 Beam section 26 Frame 27 Movable section 28 Hard magnetic body section 29 Piezoelectric element section and beam section 30 Element section substrate 31 Soft magnetic body section 32 Coil Unit 40 magnetic sensor control device 41 control unit 42 switch switching unit 43 storage unit 44 power detection unit 45 battery unit 46 external energy passive unit

Japanese Patent Laid-Open No. 08-233841 Japanese Patent Laid-Open No. 04-192385 JP 2009-222650 A JP 2006-153697 A

Claims (8)

A magnetoresistive element group by connecting a plurality of magnetoresistive elements in parallel or in series, having a cell connected to a plurality of said magnetoresistive element element group in parallel, comprising the cells are connected in parallel and / or series A detection unit ;
A first switch section that switches connection for at least one of the magnetoresistive element groups;
A second switch section for switching connection for at least one of the cells;
A magnetic sensor that detects a current of the current source using the magnetic field generation source as a current source ,
A switch switching unit that switches between the first switch unit and / or the second switch unit based on the frequency, amplitude, and phase signals of the current ;
When the detection is performed by selecting the magnetoresistive element group and / or the cell sequentially in different combinations by the switch switching unit and the detection accuracy satisfies a predetermined noise-to-signal output condition, it is selected at that time. And a control unit that performs detection by a combination and repeats detection by selecting another combination when the predetermined noise-to-signal output condition is not satisfied . An AC magnetic field application unit is provided in the vicinity of the detection unit,
Varying the magnitude of the external magnetic field of the magnetoresistive element constituting the detection unit,
The control means, the frequency of the current, based on the amplitude and phase of the signal, the magnetic sensor control device according to claim 1, wherein the controller controls the alternating magnetic field applying unit. The detection unit is disposed on the substrate together with the piezoelectric element,
An AC voltage is applied to the piezoelectric element to vibrate the substrate, and the magnitude of the external magnetic field of the magnetoresistive element constituting the detection unit is varied,
The control means, the frequency of the current, based on the amplitude and phase of the signal, the magnetic sensor control device according to claim 1, wherein the controller controls the piezoelectric element. A movable part having a hard magnetic body part made of a hard magnetic material is provided in the vicinity of the detection part,
The hard magnetic body portion is displaced by driving the movable portion, the magnitude of the external magnetic field of the magnetoresistive element constituting the detection portion is varied,
The control means, a magnetic sensor control device according to claim 1, the frequency of the current, based on the amplitude and phase of the signal, and controls the moving part. A movable part having a soft magnetic body part and a coil member made of a soft magnetic material is provided in the vicinity of the detection part,
By applying a direct current to the coil member and driving the movable part in a state where the soft magnetic part is magnetized, the soft magnetic part is displaced, and the outside of the magnetoresistive element constituting the detection part Vary the magnitude of the magnetic field,
The control means, a magnetic sensor control device according to claim 1, the frequency of the current, based on the amplitude and phase of the signal, and controls the moving part. The control means includes a power detection unit that detects power consumption or / and applied voltage of the device,
The magnetic sensor control device according to any one of claims 1 to 5 based on the detection by said power detection unit and controls the magnetic sensor. The control means includes a battery unit serving as a power source for the device,
The magnetic sensor control device according to claim 6 , wherein the magnetic sensor is controlled based on detection by the power detection unit and the battery unit. The control means includes an external energy passive unit that passively passes external energy serving as a power source for the device,
Wherein detection by the power detection unit, and the external energy driven mechanism magnetic sensor control device according to claim 6 or 7, wherein the controller controls the magnetic sensor based on.

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